Aqueous-PREP: A Pragmatic Randomized Trial Evaluating Pre-operative Aqueous Antiseptic Skin Solutions in Open Fractures
Phase: PHASE4
Conditions: Surgical Site Infection, Unplanned Fracture-Related Reoperation, Open Appendicular Fracture
Sponsor: University of Maryland, Baltimore

 
 
PREP-IT 
A Program of Randomized trials to Evaluate Pre-operative 
antiseptic skin solutions In orthopaedic Trauma 
 
 
 
Aqueous-PREP: A Pragmatic Randomized trial Evaluating Pre-
operative aqueous antiseptic skin solutions in open fractures 
 
 
 
 
Aqueous-PREP PROTOCOL 
 
 
Version: 2.1 
 
Date: 04-Nov-2019 
 
This study is funded by the US Department of Defense, Physician Services Incorporated, 
and McMaster University Surgical Associates. 
 
The Aqueous-PREP trial is part of the PREP-IT research program. The protocol is the 
confidential intellectual property of the Principal Investigators and PREP-IT Steering 
Committee, and the protocol cannot be used in any form without the expressed written 
permission of the Principal Investigators. 
 
Reviewed and Approved by: 
  
 
Dr. Gerard Slobogean  
(Principal Investigator)  
Signature: 
Date: 04-Nov-2019 
 
Dr. Sheila Sprague 
(Principal Investigator) 
Signature: 
Date: 04-Nov-2019 
 
Dr. Mohit Bhandari  
(Principal Investigator) 
Signature: 
 
Date: 04-Nov-2019 
 
 
 
 
 

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TABLE OF CONTENTS  
 
LIST OF ABBREVIATIONS .......................................................................................... 4 
STUDY SUMMARY ......................................................................................................... 5 
1.0 INTRODUCTION ....................................................................................................... 7 
1.1 Open Fractures .............................................................................................................. 7 
1.2 Prevention of Infection ................................................................................................. 7 
1.3 Rationale for Pre-Operative Antiseptic Skin Solution Prophylaxis .............................. 7 
1.4 Extrapolating Evidence from Other Surgical Disciplines to Fracture Surgery is 
Problematic ......................................................................................................................... 8 
1.5 Why Iodophor Skin Preparations May Reduce Open Fracture SSI .............................. 9 
1.6 Why Iodophor Skin Preparations May Reduce Open Fracture Reoperations .............. 9 
1.7 Lack of Surgeon Consensus ........................................................................................ 10 
2.0 STUDY OBJECTIVES AND HYPOTHESES ....................................................... 10 
2.1 Study Objectives and Hypotheses ............................................................................... 10 
2.2 Subgroup Objectives ................................................................................................... 10 
3.0 TRIAL DESIGN ........................................................................................................ 11 
3.1 Summary ..................................................................................................................... 11 
3.2 Pragmatic-Explanatory Continuum ............................................................................ 11 
4.0 METHODS ................................................................................................................ 13 
4.1 Study Setting, Cluster Eligibility, and Selection of Clusters ...................................... 13 
4.2 Eligibility Criteria ....................................................................................................... 14 
4.3 Recruitment Strategy .................................................................................................. 15 
4.3.1 Patient Screening and Consent ................................................................................. 15 
4.3.2 Enrollment Sampling Plan ....................................................................................... 16 
4.4 Randomization Methods ............................................................................................. 16 
4.5 Blinding ....................................................................................................................... 17 
4.6 Description of the Interventions .................................................................................. 17 
4.6.1 Initial Run-In Phase ................................................................................................. 17 
4.6.2 First Intervention Phase ........................................................................................... 17 
4.6.3 Second Intervention Phase ....................................................................................... 18 
4.6.4 Special Considerations for Ongoing Treatment Crossovers .................................... 18 
4.6.5 Evaluation of Site Performance and Removal of Clinical Sites .............................. 18 
4.6.6 Application of Pre-Operative Antiseptic Skin Solutions ......................................... 18 
4.6.7 Povidone-Iodine Treatment ..................................................................................... 19 
4.6.8 Chlorhexidine Gluconate Treatment ........................................................................ 20 
4.7 Perioperative Co-Interventions ................................................................................... 20 
4.8 Outcome Measures ...................................................................................................... 20 
4.8.1 Primary Outcome ..................................................................................................... 20 
4.8.2 Secondary Outcome ................................................................................................. 22 
4.8.3 Exploratory Outcomes ............................................................................................. 23 
4.8.4 Data Collection and Participant Follow-up .............................................................. 24 
5.0 STATISTICAL PLAN .............................................................................................. 25 

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5.1 Sample Size Determination ......................................................................................... 25 
5.2 Statistical Methods ...................................................................................................... 26 
5.2.1 Analysis Plan Overview ........................................................................................... 26 
5.2.2 Analysis of the Study Outcomes .............................................................................. 26 
5.2.3 Subgroup Analyses .................................................................................................. 27 
5.2.4 Sensitivity Analyses ................................................................................................. 28 
5.2.5 Interim Analysis ....................................................................................................... 30 
6.0 DATA MANAGEMENT .......................................................................................... 30 
6.1 Case Report Forms and Data Transmission ................................................................ 30 
6.2 Data Integrity .............................................................................................................. 30 
7.0 ETHICS AND DISSEMINATION .......................................................................... 30 
7.1 Research Ethics Approval ........................................................................................... 30 
7.2 Consent ....................................................................................................................... 30 
7.3 Confidentiality ............................................................................................................ 32 
7.4 Protocol Amendments ................................................................................................. 32 
7.5 Adverse Event Reporting and Definitions .................................................................. 32 
7.5.1 Serious Adverse Event (SAE) .................................................................................. 32 
7.5.2 Unanticipated Problems Resulting in Risk to Participant or Others ........................ 32 
7.5.3 Clinical Site Reporting: Notifying the Methods Center .......................................... 33 
7.5.4 Clinical Site Reporting – IRB and REB .................................................................. 33 
7.5.5 Safety Monitoring .................................................................................................... 33 
7.6 Dissemination Policy .................................................................................................. 33 
8.0 DEPARTMENT OF DEFENSE REPORTING REQUIREMENTS ................... 33 
9.0 SUB-STUDY: PATIENT EXPERIENCES IN THE AQUEOUS-PREP AND 
PREPARE TRIALS ........................................................................................................ 34 
9.1 Introduction ................................................................................................................. 34 
9.2 Rationale and Objectives ............................................................................................ 35 
9.3 Sub-Study Design ....................................................................................................... 35 
9.4 Survey Participants and Distribution .......................................................................... 35 
9.5 Data Entry ................................................................................................................... 36 
9.6 Sample Size ................................................................................................................. 36 
9.7 Data Analysis .............................................................................................................. 36 
9.8 Anticipated Implications of Results ............................................................................ 36 
10.0 REFERENCES ........................................................................................................ 37 
 
 
 
 
 
 
 
 
 
 

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LIST OF ABBREVIATIONS  
Abbreviation 
Explanation 
 
Aqueous-PREP 
 
CDC 
CEO 
CHG 
CI 
CRF 
EDC 
FDA 
FLOW 
FRI 
GEE 
HRPO 
ITT 
IRB 
ORP 
REB 
SAE 
SSI 
USAMRMC 
A Pragmatic Randomized trial Evaluating Pre-operative aqueous 
antiseptic skin solutions in open fractures 
Centers for Disease Control and Prevention 
Center for Evidence-Based Orthopaedics 
Chlorhexidine gluconate 
Confidence interval 
Case report form 
Electronic data capture 
Food and Drug Administration 
Fluid Lavage of Open Wounds trial 
Fracture-related infection 
Generalized estimating equations 
Human Research Protection Office 
Intention-to-treat 
Institutional Review Board 
Office of Research Protections 
Research Ethics Board 
Serious adverse event 
Surgical site infection 
United States Army Medical Research and Materiel Command  

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STUDY SUMMARY   
 
Methodology 
Cluster randomized crossover design. 
Coordinating Center 
This study will be centrally coordinated by the Methods Center at the 
Center for Evidence-Based Orthopaedics (CEO), McMaster 
University, Hamilton, Ontario and by the Administrative Center 
within the Department of Orthopaedics at the University of 
Maryland, R Adams Cowley Shock Trauma Center, Baltimore, 
Maryland.  
Clinical Sites 
At least 12 clinical sites. Additional clinical sites will be included or 
removed as needed. 
Background 
The prevention of infection is the single most important goal 
influencing peri-operative care of patients with open fractures.  
Standard practice in the management of open fractures includes 
sterile technique and pre-operative skin preparation with an antiseptic 
solution. The available solutions kill bacteria and decrease the 
quantity of native skin flora, thereby decreasing surgical site infection 
(SSI).1–4  While there is extensive guidance on specific procedures 
for prophylactic antibiotic use and standards for sterile technique, the 
evidence regarding the choice of antiseptic skin preparation solution 
is very limited for open fracture surgery.  
Objectives 
The overall objective is to compare the effectiveness of aqueous pre-
operative antiseptic skin preparation with 10% povidone-iodine 
versus 4% chlorhexidine gluconate (CHG) for the management of 
open fractures. A ranked order for assessing effectiveness will be 
used with surgical site infection (SSI) as the primary comparison and 
unplanned 
fracture-related 
reoperations 
as 
the 
secondary 
comparison. 
Subgroup Objectives 
We will explore if the pre-operative antiseptic skin solutions have 
different magnitudes of effect on SSI within three clinically 
important open fracture subgroups: severity of open fracture, location 
of fracture, and severity of wound contamination. 
Diagnosis and Main 
Inclusion Criteria 
All patients 18 years of age or older who present to a recruiting 
hospital for treatment of an open fracture(s) of the appendicular 
skeleton will be screened for participation within 3 weeks of their 
fracture. Eligible patients must receive surgical debridement of their 
open fracture wound(s) within 72 hours of their injury and the open 
fracture(s) must be managed definitively with a surgical implant (e.g., 
internal fixation, external fixation, joint prosthesis, etc.).  

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Treatment Groups  
The Aqueous-PREP trial will compare two common iodophor and 
chlorhexidine based pre-operative antiseptic skin solutions used 
during open fracture surgery: 1) Povidone-iodine: 10% povidone-
iodine (1% free iodine) in purified water and 2) CHG: 4% 
chlorhexidine gluconate in purified water. 
Randomization 
Treatment allocation will be determined using a cluster-randomized 
crossover trial design. The order of treatment allocation for each 
orthopaedic practice will be randomly assigned using a computer-
generated randomization table. Each site will start with the initially 
allocated study solution and eventually crossover to the other solution 
for their second recruitment period. This process of alternating 
treatments will repeat approximately every 2 months as dictated by 
the initial randomization.  
Study Outcomes 
The primary outcome is SSI, guided by the Centers for Disease 
Control and Prevention’s (CDC) National Healthcare Safety Network 
reporting criteria,5 which includes superficial incisional SSI within 
30 days and deep incisional or organ/space SSI within 90 days of 
definitive fracture management surgery. The secondary outcome is 
the occurrence of an unplanned fracture-related reoperation within 12 
months of the fracture.  Alternative definitions of SSI, including the 
confirmatory criteria for Fracture-Related Infection (FRI) and the 
CDC criteria within 1 year of injury will be used for sensitivity 
analyses of the primary comparison. All study outcomes will be 
adjudicated by a blinded committee using clinical notes and 
radiographs.  
Follow-Up  
Study participants will be followed at 6 weeks, 3 months, 6 months, 
9 months, and 12 months from their fracture.  
Sample Size 
A minimum of 1,540 participants with open fractures.  
Significance 
SSIs are often devastating complications for open fracture patients 
because of the resultant reoperations, adverse events from antibiotic 
courses, and fracture healing difficulties.  Given the severity of open 
fractures, maximizing the effectiveness of current prophylactic 
procedures is essential. The Aqueous-PREP trial will provide 
necessary evidence to guide the prevention of SSIs in open fractures, 
and the trial is poised to have a significant impact on the care and 
outcomes of open extremity fracture patients.  

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1.0 INTRODUCTION 
 
1.1 Open Fractures 
Open fractures represent some of the most severe musculoskeletal injuries.6 Due to their high-
energy mechanisms, these extremity fractures are accompanied by soft-tissue injuries that 
contribute to unacceptably poor outcomes. The Fluid Lavage of Open Wounds (FLOW) trial of 
2,447 open fracture patients reported a 13.2% incidence of open fracture-related reoperations; 7 
however, these study events were even more common in open wounds with severe contamination 
(29.8%, 95% confidence interval (CI): 22.6–38.1%) and in patients with higher grades of injury 
(Gustilo-Anderson Type III: 18.0%, 95% CI: 15.6–20.7%).  Ultimately, complications from open 
fractures lead to prolonged morbidity, loss of function, and potential limb loss.8  
 
1.2 Prevention of Infection 
The prevention of infection is the single most important goal influencing peri-operative care of 
patients with open fractures. Standard practice in the management of open fractures includes sterile 
technique and pre-operative skin cleaning with an antiseptic solution. The available solutions kill 
bacteria and decrease the quantity of native skin flora, thereby decreasing surgical site infection 
(SSI).1–4  While there is extensive guidance on specific procedures for prophylactic antibiotic use 
and standards for sterile technique, the evidence regarding the choice of antiseptic skin preparation 
solution is very limited for open fracture surgery.  
 
1.3 Rationale for Pre-Operative Antiseptic Skin Solution Prophylaxis 
The most common skin preparation solutions include either an iodophor or chlorhexidine-based 
active ingredient, and are delivered in an alcohol or aqueous-based solution. Iodophors achieve 
effective antisepsis by penetrating the cell wall of microorganisms and disrupting critical protein 
and nucleic acid structures.9 Iodophors are effective against most bacteria, but also may have 
broader-spectrum coverage of mycobacteria, viruses, and some spores compared to chlorhexidine 
gluconate (CHG).9 CHG similarly achieves antimicrobial effects by penetrating the cell wall of 
microorganisms. This antimicrobial action allows CHG to be effective against most bacteria.9 
 
The evidence guiding pre-operative antiseptic skin solution choice in fracture surgery is largely 
extrapolated from other surgical disciplines. In a randomized controlled trial involving 849 patients 
undergoing clean-contaminated abdominal, gynecologic, or urologic surgery, the use of 2% CHG 
in 70% isopropyl alcohol was compared to aqueous 10% povidone-iodine. The overall rate of 30-
day SSI was significantly lower in the CHG-alcohol group than the povidone-iodine group (9.5% 
vs. 16.1%; P=0.004; relative risk, 0.59; 95% CI: 0.41–0.85). While this study demonstrated 
superior efficacy of CHG-alcohol compared to povidone-iodine, comparing an alcohol based 
solution to an aqueous solution creates uncertainty about whether the result observed occurred 
from the superiority of CHG over iodine, isopropyl alcohol over water, or a synergistic 
combination of CHG with alcohol.1  In an effort to overcome the controversies associated with 
comparing CHG and iodine in different solutions, a more recent randomized controlled trial of 
1,147 caesarean section patients allocated patients to 2% CHG with 70% isopropyl alcohol versus 
8.3% povidone-iodine with 72.5% isopropyl alcohol. Similar to the previous randomized 
controlled trial, CHG proved more efficacious for reducing 30-day SSI (4.0% in the CHG-alcohol 
group and 7.3% in the iodine-alcohol group; relative risk, 0.55; 95% CI: 0.34–0.90; P=0.02).2   
 

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While the evidence from the above two randomized controlled trials demonstrate decreased SSI 
from CHG solutions in clean-contaminated abdominal and genito-urinary surgery, a larger non-
randomized trial reported opposite effectiveness results. Swenson et al., completed a larger 3,209 
patient pragmatic sequential implementation study, in which the use of the preoperative skin 
antiseptic solution was changed after six-month periods.4 In this study, there were three treatment 
periods, each with approximately 1,000 general surgery patients undergoing elective and emergent 
cases. In the first period, patients received 7.5% povidone-iodine scrub, 70% isopropyl alcohol 
scrub, and 10% povidone-iodine skin paint. The second group received 2% CHG with 70% 
isopropyl alcohol (CHG group), and the third group received 0.7% iodine povacrylex in 74% 
isopropyl alcohol. Adjusted comparisons were performed using the intention to treat principle and 
an as-treated analysis. Lower SSI rates were seen in the povidone-iodine skin paint group (4.8%) 
and the iodine povacrylex in isopropyl alcohol group (4.8%), compared with the SSI rates in the 
2% chlorhexidine and 70% isopropyl alcohol group (8.2%) (P< 0.05; povidone-iodine skin paint 
odds ratio: 0.56, 95% CI: 0.40–0.79).4 While the results of the Swenson study contradict those of 
the smaller randomized controlled trials, this large pragmatic study further highlights that the 
choice of antiseptic skin solution affects SSIs, and data to select the best solution remains 
conflicting. 
 
Considering the conflicting data, the most recent Cochrane systematic review comparing the 
efficacy of pre-operative antiseptic skin solutions for clean surgery concluded, “investment in at 
least one large trial (in terms of participants) is warranted to add definitive and hopefully 
conclusive data to the current evidence base. Ideally any future trial would evaluate the iodine-
containing and chlorhexidine-containing solutions relevant to current practice…”10 The Cochrane 
recommendation is a direct response to the limitations of the current available literature comparing 
antiseptic skin solutions. For orthopaedic fracture surgery, the impact of the treatment uncertainty 
is further magnified when considering the higher rates of SSIs among open fracture patients. 
 
1.4 Extrapolating Evidence from Other Surgical Disciplines to Fracture Surgery is Problematic 
With regards to orthopaedic patients, the inconsistent results leave the optimal antiseptic solution 
in doubt; in addition, results may differ across surgical settings. The risk of SSI is substantially 
greater in open fracture patients due to both the nature of the injury and the required surgery to fix 
broken bones. Furthermore, the emergent nature of fracture surgery means that patients are unable 
to undergo other prophylactic skin care, such as CHG bathing, which is rendered to elective cases 
to reduce SSI. 
 
Most important, the contamination from the injury is a critical difference from elective abdominal 
or gynecologic surgery. Other differences include substantial soft tissue damage during the injury, 
the use of a tourniquet that decreases the blood flow to the limb (potentially increasing the risk of 
infection), and the additional risk of implanting metal fixation that can harbor bacteria. Swenson 
et al., directly acknowledged that the studies performed in general surgery patients may not apply 
to other specialties, particularly orthopaedic surgery.4 Even if one wanted to directly apply the 
conflicting results outlined above to the care of open fractures, there are critical limitations in the 
sparse general surgery and obstetrical literature available.  
 
The most significant limitation in the existing literature is the use of a 30-day endpoint for SSI in 
all three studies described above.1,2,4 While this may be acceptable for identifying most SSIs that 

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involve only the skin (superficial SSI), infections that occur deep to the muscle and around the 
bone (deep SSI and organ/space SSI) often present beyond 30-days post-injury and have 
significantly more morbidity and mortality than superficial SSI. This is a major limitation to the 
external validity of the previous studies’ ability to guide fracture fixation practice. In the FLOW 
open fracture trial, nearly half the infection-related complications were identified between 30 and 
90 days from injury.7 Not only does the existing literature not extend follow-up during this period, 
it is plausible that the treatment effects of the antiseptic solutions behave differently for preventing 
deep or organ/space infections that often present between 30 and 90 days post-surgery. The need 
for longer follow-up is supported by a mandatory 90-day surveillance period for deep and 
organ/space SSIs according to the Centers for Disease Control and Prevention (CDC).5 Therefore, 
the lack of directly applicable evidence, an overall paucity of good clinical evidence, and the 
inadequate duration of outcome follow-up mandate the need for a large, rigorous clinical trial in 
surgical preparation solutions in open fracture care. 
 
1.5 Why Iodophor Skin Preparations May Reduce Open Fracture SSI 
The only surgical skin preparation effectiveness data available for open fracture management come 
from the FLOW trial.7 Secondary multivariable analyses of 2,447 patients with open fractures 
found that when compared to chlorhexidine solutions, iodophor-based skin antiseptic preparation 
solutions could be protective against complications (Adjusted Hazard Ratio 0.88, 95% CI: 0.69–
1.12).7 However, the wide CI suggests iodophor solutions may reduce the odds of infection by as 
much as 31% or increase it by as much as 12%, leaving its superiority as a fracture care surgical 
preparation solution unresolved.7 
 
There are several chemical properties to suggest povidone-iodine may be more effective than CHG 
at preventing open fracture SSI.9 Firstly, povidone-iodine has a broader spectrum of antimicrobial 
activity.9 Secondly, many open fracture patients require repeat surgical debridement and therefore, 
these patients will receive multiple exposures to the pre-operative antiseptic solution. Extended 
use of povidone-iodine has not been associated with the selection of resistant bacterial strains, 
whereas bacterial resistance to chlorhexidine has been documented.9,11,12 While the methods for 
detecting CHG resistance are challenging and its clinical significance remains uncertain, these 
early observations heighten interest in establishing the comparative effectiveness of iodophors 
versus CHG. 
 
1.6 Why Iodophor Skin Preparations May Reduce Open Fracture Reoperations 
While the primary rationale for using antiseptic skin preparation solutions is to reduce the risk of 
SSI, many fracture healing complications are associated with indolent infections. These low-grade 
infections typically do not exhibit clinical signs consistent with SSI. Instead, they present several 
months post-fracture fixation and are only detected from deep tissue samples collected during 
secondary surgeries to treat fractures that fail to heal (nonunion). Previous fracture non-union 
studies have identified an infectious etiology in 31–38% of cases.13,14 Similarly, results from the 
FLOW trial suggest that 58% of the reoperation events were caused by fracture nonunion or a 
hardware failure related to infection, wound-healing problem, or bone-healing problem (n= 
188/323). In addition, among a series of 211 patients requiring reoperation for deep post-operative 
fracture infections, 40% of open fracture infections occurred beyond the 90-day surveillance 
period for SSI.15 Therefore, given the rationale that povidone-iodine may be more effective in 

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preventing SSI, it is clinically plausible that its use may also reduce unplanned open fracture 
reoperations. 
 
1.7 Lack of Surgeon Consensus 
The FLOW trial demonstrated a clear divide among orthopaedic surgeons regarding their choice 
to use the two most common antiseptic solutions during open fracture fixation surgery.7 Iodophor 
solutions were used in 54% of the surgeries performed, while 41% were performed using 
chlorhexidine solutions. The remaining surgeons either used both iodophor and chlorhexidine 
(4%), or alcohol with no iodophor or chlorhexidine (1%).7 Building upon the lack of consensus 
among orthopaedic surgeons participating in the FLOW trial, our research team conducted an 
internet-based survey and several interviews with orthopaedic surgeons to understand the reasons 
for the lack of consensus in the use of surgical preparation solutions. Similar to the observations 
of the FLOW trial, there was nearly an equal split between the use of iodophor and chlorhexidine 
solutions. More insight was gained in interviews with the surgeons. Three main drivers for surgeon 
decision-making were identified: 1) they continued to use the antiseptic solution shown to them 
during their surgical training, 2) they used the solution recommended by their hospital, or 3) they 
felt the tissue toxicity was less with their chosen solution. No surgeon could cite a clinical study 
that helped guide their decision, despite all surgeons indicating they believed the antiseptic 
solution was important for reducing their patient’s risk of SSI. Limited consensus among surgeons 
reflects a lack of compelling evidence on the optimal approaches to surgical skin preparation, 
further vindicating the need for a large definitive trial. 
 
The Aqueous-PREP trial, A Pragmatic Randomized trial Evaluating Pre-operative aqueous 
antiseptic skin solutions in open fractures, will address these gaps in the literature. 
 
2.0 STUDY OBJECTIVES AND HYPOTHESES 
 
2.1 Study Objectives and Hypotheses 
The overarching objective of this trial is to compare the effectiveness of an aqueous pre-operative 
antiseptic skin preparation with 10% povidone-iodine versus 4% CHG for the management of open 
fractures. A ranked order for assessing effectiveness will be used, with surgical site infection (SSI) 
as the primary comparison (primary objective) and unplanned fracture-related reoperations as the 
secondary comparison (secondary objective). While previous randomized controlled trials in 
general surgery and gynecology demonstrated superior efficacy of chlorhexidine-alcohol solutions 
to reduce SSIs,1,2 results from larger populations of general surgery patients and the recently 
completed FLOW trial7 suggest iodophor-based solutions could be more effective than 
chlorhexidine in open fracture patients. Therefore, we hypothesize that aqueous solutions of 10% 
povidone-iodine will be more effective than aqueous 4% CHG to reduce 90-day SSIs or unplanned 
fracture-related reoperations within one year of injury. 
 
2.2 Subgroup Objectives 
The Aqueous-PREP trial will also explore the possibility of differential treatment effects of the 
pre-operative antiseptic skin solutions among clinically important open fracture subgroups. 
Subgroups will be defined by: i) the severity of open fracture (Gustilo-Anderson type I or II versus 
III);8 ii) upper extremity versus lower extremity open fractures; and iii) severity of wound 
contamination. High-grade soft tissue injury (Gustilo-Anderson type III), lower extremity open 

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fractures, and moderate/severe wound contamination are established predictors of SSI and 
reoperations from the FLOW trial.16 In addition, there are known differences in patients’ skin flora 
based on anatomic region of injury. As a result, it is likely that the study interventions may be 
more effective in certain subgroups. Due to its broader spectrum of antimicrobial activity, the 
increased effectiveness observed by Swenson et al., and the possible benefits observed in the 
FLOW trial, we hypothesize that 10% povidone-iodine antiseptic skin solution will be associated 
with a larger reduction in odds for SSI and reoperation in open fracture patients with worse fracture 
severity, lower extremity fractures, and more severely contaminated wounds. 
 
3.0 TRIAL DESIGN 
 
3.1 Summary 
This study is a multi-center pragmatic cluster randomized crossover trial of a minimum of 1,540 
participants with open extremity fractures requiring surgical management. The unit of 
randomization is the orthopaedic practices within clinical sites (clusters), with individual patients 
being the unit of analysis. Recruitment for each treatment group will be performed in multiple 
iterations of approximately two-month periods. Each orthopaedic practice will initially be 
randomized to use one of two pre-operative aqueous surgical skin preparation solutions (10% 
povidone-iodine or 4% CHG) for open fracture surgeries at their institution (Figure 1). Upon 
completion of the two-month period, each orthopaedic practice will crossover to the alternative 
treatment allocation and complete another two-month recruitment period. This process of 
alternating treatment periods (crossovers) will continue until the minimum sample size is achieved 
and the study’s budgeted recruitment duration is completed. Upon completion of recruitment, it is 
expected that each orthopaedic practice will enroll a minimum of 77 patients per treatment, and 
that most clinical sites will exceed this minimum recruitment goal. Clinical site personnel will 
screen potential patients for eligibility, and if eligible, they will be invited to participate in the trial. 
Study participants will be assessed at regular intervals in the one year following their fracture. The 
primary outcome will include any SSI event from the time of open fracture to the end of the 30- 
and 90-day post-operative periods from their definitive fracture management surgery. The 
secondary outcome will include unplanned fracture-related reoperations that occur within one-year 
of their fracture. A blinded Adjudication Committee will review SSIs and unplanned fracture-
related reoperations to confirm that they meet the criteria for being a study event. 
Figure 1: Randomized Treatment Allocation, Cluster Crossover, and Recruitment 
 
3.2 Pragmatic-Explanatory Continuum 
In accordance with recommended methodology standards, we have used the PRagmatic-
Explanatory Continuum Indicator Summary (PRECIS-2) toolkit to evaluate the Aqueous-PREP 
trial design decisions to determine whether these decisions will lead to a study that answers, “Does 
this intervention work under usual conditions?” (pragmatic) versus “Can this intervention work 

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under ideal conditions?” (explanatory). The PRECIS-2 tool uses a 5-point Likert scale in 9 
domains to evaluate the continuum of design choices. A domain score of 5 indicates “very 
pragmatic,” while a score of 1 suggests “very explanatory.” Table 1 outlines the investigators’ 
assessment of the trial design and the rationale for each assessed score and Figure 2 displays the 
PRECIS-2 wheel. 
 
Table 1: PRECIS-2 Score 
Domain 
Score 
Rationale 
Eligibility 
5 
Eligibility criteria are very broad and include all fracture patients that would be 
treated in all hospital environments. 
Recruitment 
5 
Recruitment of all consenting fracture patients treated at each participating 
hospital will be performed. 
Setting 
4 
Recruitment is occurring at multiple sites across the US and Canada; however, 
since most of the recruiting hospitals are regional referral centers the setting is 
“mostly pragmatic.” 
Organization 
5 
The interventions do not need an increase in providers or care delivery 
compared to the usual antiseptic care provided. For each antiseptic solution, a 
brief in-service training session will be provided to the clinical sites, as per any 
new product/procedure that is being introduced into an operating room. 
Flexibility (delivery) 
5 
The interventions will be delivered in the usual care manner with no advice on 
allowed co-interventions or strict protocols to ensure compliance. 
Flexibility (adherence) 
- 
This section is left blank according to PRECIS-2 guidance because the 
intervention is provided prior to patient consent and individual patient 
compliance is not an issue. If provider adherence is considered, the study design 
is rather pragmatic (4) because there will be limited encouragement to follow 
the manufacturer’s directions for use, other than periodic newsletters, 
investigator meetings, and possible provider survey during the recruitment 
period. 
Follow-up 
5 
All study follow-up is consistent with usual care. 
Primary outcome 
5 
The outcome has been validated by patients as being very relevant to the study 
participants and it does not require specialized expertise beyond the treating 
physician for diagnosis. 
Primary analysis 
5 
All available study data will be used for analysis following the intention to treat 
principle. 
 
 
 

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Figure 2: PRECIS-2 Wheel 
 
4.0 METHODS 
 
4.1 Study Setting, Cluster Eligibility, and Selection of Clusters 
This study will be coordinated by the Methods Center at the Center for Evidence-Based 
Orthopaedics (CEO), McMaster University, Hamilton, Ontario and by the Administrative Center 
within the Department of Orthopaedics at the University of Maryland School of Medicine, R 
Adams Cowley Shock Trauma Center, Baltimore, Maryland. Patients will be enrolled from at least 
12 clinical sites. Clusters (orthopaedic practices within clinical sites) will be carefully screened 
prior to participation in the Aqueous-PREP study. Clinical site inclusion criteria are: 1) adequate 
research personnel infrastructure to manage the study; 2) adequate open fracture volume to 
complete enrollment within the study timeline (i.e., a minimum of 77 open fractures per year); 3) 
commitment from all or most orthopaedic surgeons to participate in the trial; and 4) ability to use 
the two aqueous-based preparation solutions. The exclusion criteria are: 1) lack of interest in the 
trial; 2) anticipated challenges with complying with the protocol; 3) conflicting studies, in the 
judgment of the Principal Investigators, that would inhibit patient participation; and 4) budgeting 
or contract constraints.  
 
The screening process will begin with potential clinical sites completing a feasibility questionnaire 
that asks about research experience and infrastructure, open fracture volume, current practice 
patterns, and interest in participating in the trial. Clinical sites that meet the eligibility criteria at 
this stage will be invited to participate in a series of teleconferences to review study and clinical 
logistics in detail with members of the study team. The Principal Investigators and study personnel 

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will further vet the clinical sites during these calls and will ask about hospital and patient 
demographics to ensure that a variety of fracture patient populations and referral patterns, ranging 
from large urban trauma centers to rural community hospitals, are included in the Aqueous-PREP 
study. Study personnel will document reasons for clinical site ineligibility. Upon selection, clinical 
sites will be asked to complete a questionnaire that will detail current surgeon preferences and 
practices for pre-operative surgical preparation techniques and co-interventions known to 
influence the incidence of SSIs (see Section 4.7). 
 
4.2 Eligibility Criteria 
Broad eligibility criteria will be used to increase the generalizability of the trial.   
  
The inclusion criteria are: 
1. Patients 18 years of age or older. 
2. Open fracture of the appendicular skeleton. 
3. Received or will receive definitive fracture treatment with a surgical implant(s) (e.g., 
internal fixation, external fixation, joint prosthesis, etc.). 
4. Open fracture wound management that includes formal surgical debridement within 72 
hours of their injury. 
5. Will have all planned fracture care surgeries performed by a participating surgeon or 
delegate. 
6. Informed consent obtained. 
7. Patient enrolled within 3 weeks of their fracture. 
 
The exclusion criteria are: 
1. Patients that did not or will not receive the allocated pre-operative surgical preparation 
solution due to a medical contraindication. 
2. Received previous surgical debridement or management of their open fracture at a non-
participating hospital or clinic. 
3. Open fracture managed outside of the participating orthopaedic service (e.g., hand fracture 
managed by plastic surgeon).  
4. Chronic or acute infection at or near the fracture site at the time of initial fracture surgery. 
5. Burns at the fracture site. 
6. Incarceration. 
7. Expected injury survival of less than 90 days. 
8. Terminal illness with expected survival less than 90 days. 
9. Previous enrollment in a PREP-IT trial. 
10. Currently enrolled in a study that does not permit co-enrollment. 
11. Unable to obtain informed consent due to language barriers. 
12. Likely problems, in the judgment of study personnel, with maintaining follow-up with the 
patient. 
13. Excluded due to sampling strategy. 
 
Additional eligibility considerations: 
1. Patients with multiple open fractures will be eligible for inclusion. Study personnel will 
collect data on up to three open fracture regions.  In patients with more than three open 
fracture regions, the treating surgeon will determine the three most severe open fractures. 

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For each open fracture, the entire injured anatomic region will be included.17 Therefore, if 
there are two open fractures that anatomically communicate, they will be considered within 
the same region (e.g. within the shoulder region, forearm, etc.).  Similarly, adjacent closed 
fractures that anatomically communicate with the open fracture or are treated within the 
same surgical incision will be included. Common examples of these include forearm 
fractures, tibia/fibula fractures, and peri-articular fractures. The anatomic joint region, 
adjacent fractures, and contiguous wounds will be defined at the time of patient enrollment 
on the case report forms (CRFs).  
2. All open fractures should be treated as per cluster randomization.    
3. At the time of screening, patients who are in another study who meet eligibility criteria are 
to be included in the Aqueous-PREP trial unless the other trial does not permit co-
enrollment. 
 
4.3 Recruitment Strategy  
4.3.1 Patient Screening and Consent 
Patients 18 years of age or older who present to a recruiting hospital for treatment of an open 
fracture will be screened for participation within 3 weeks of their fracture. To screen patients 
presenting with an open fracture(s) for eligibility, designated study personnel at each clinical site will 
develop a patient enrollment plan. This plan will typically consist of daily participation in orthopaedic 
patient rounds and a review of daily listings of hospital admissions for patients with open fractures. 
Upon identification, the study personnel will screen the patient for eligibility and if eligible, approach 
them for informed consent. Study participants must be enrolled within 3 weeks of their fracture(s) 
and enrollment may take place at any time within this window.  If the patient is unable to provide 
informed consent (e.g., due to their injury) at the time they were initially identified, informed consent 
may be delayed until they are able to provide informed consent. Alternatively, if the patient is unable 
to provide informed consent, informed consent may be obtained from their proxy, with consent 
obtained from the patient when/if the patient is able to provide consent. Allowing informed consent 
from a patient’s proxy healthcare decision maker will reduce the risk of recruitment bias against the 
most severely injured patients. In addition, potentially eligible patients will be approached to 
participate in the trial, even if they did not receive the correct pre-operative antiseptic skin solution. 
This is consistent with the intention-to-treat principle (ITT) and is necessary to maintain the 
prognostic balance achieved during the cluster randomization. All screened patients will be 
classified as included, excluded, or missed. See Table 2 below for the Schedule of Events. 
 
Table 2: Schedule of Events 
Assessment 
Visit 1: 
Enrollment 
Visit 2: 
6 weeks 
post-fracture 
Visit 3: 
3 months 
post-fracture 
Visit 4: 
6 months 
post-fracture 
Visit 5: 
9 months 
post-fracture 
Visit 6: 
12 months 
post-fracture 
Eligibility 
Screening  
● 
 
 
 
 
 
Informed 
Consent  
● 
 
 
 
 
 
Collection of 
Demographic 
and Fracture 
Characteristics 
Data 
● 
 
 
 
 
 
Collection of 
Surgical Data 
● 
 
 
 
 
 

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Assessment 
Visit 1: 
Enrollment 
Visit 2: 
6 weeks 
post-fracture 
Visit 3: 
3 months 
post-fracture 
Visit 4: 
6 months 
post-fracture 
Visit 5: 
9 months 
post-fracture 
Visit 6: 
12 months 
post-fracture 
Collection of 
Peri-Operative 
Data 
● 
 
 
 
 
 
Collection of 
Study Event 
(SSI) Data 
● 
● 
● 
● 
● 
● 
Collection of 
Reoperation 
Data 
● 
● 
● 
● 
● 
● 
Collection of 
SAE Data 
● 
● 
● 
● 
● 
● 
Informed consent and enrollment must occur within the 3 weeks (21 days) from the patient’s fracture (Day 0 is the 
date of the fracture).  
Visits are to be completed at routine clinic visits. When necessary, visits may also be completed by telephone, text, 
email, standard mail, and/or a review of the participant’s medical record.  
Follow-up visit windows touch so that participants will always fall into a specific window.  The windows are: 4 to 8 
weeks (i.e., 28 to 56 days), 2 to 4.5 months (i.e., 57 to 137 days), 4.5 to 7.5 months (i.e., 138 to 228 days), 7.5 to 12 
months (i.e., 229 to 365 days), and greater than 12 months (i.e., 366 to 730 days), respectively, from the participant’s 
fracture. 
 
4.3.2 Enrollment Sampling Plan 
When the volume of eligible patients exceeds a participating site’s ability to effectively enroll and 
follow all eligible patients, a sampling strategy may be implemented.  A sampling strategy is 
available within the REDCap Cloud electronic data capture (EDC) system which will randomly 
determine whether an eligible patient should be approached for consent and inclusion in the study. 
The randomization software will use randomly selected block sizes consistent with the sampling 
ratio being used during the recruitment periods. Examples of potential random sampling strategies 
a site may use include:  
 
1. 
For every three eligible patients, there will be one excluded eligible patient (3:1 ratio). 
2. 
For every two eligible patients, there will be one excluded eligible patient (2:1 ratio). 
3. 
For each eligible patient, there will be one excluded eligible patient (1:1 ratio). 
4. 
For each eligible patient, there will be two excluded eligible patients (1:2 ratio).  
5. 
For each eligible patient, there will be three excluded eligible patients (1:3 ratio). 
 
The number of eligible patients approached for consent and inclusion in the study, and the number 
of eligible patients that are excluded due to a sampling strategy will be documented in the EDC 
system. 
 
4.4 Randomization Methods  
Treatment allocation will be determined using a cluster-randomized crossover trial design. The 
order of treatment allocation for each orthopaedic practice (cluster) will be randomly assigned 
using a computer-generated randomization table. Each site will start with the initially allocated 
study solution and crossover to the other solution for their second recruitment period. This process 
of alternating treatments will repeat approximately every 2 months as dictated by the initial 
randomization.  For sites that enroll for more than 1 year, the order of treatment allocation may be 
reversed after 12 months to ensure equal distribution of each treatment across each calendar month 

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in the study’s duration (Figure 1). Randomization will be completed by personnel at the CEO 
Methods Center at the onset of the trial. Personnel from the Methods Center will notify personnel 
at each participating clinical site of their treatment allocation order. This will allow each 
participating clinical site to begin preparing for the first run-in period. 
 
4.5 Blinding 
The orthopaedic team (including the study coordinators) cannot be blinded to the treatment 
allocation as the antiseptic solutions are visually distinguishable and these individuals need to lead 
the implementation of the cluster-crossover protocol at their clinical site. The Adjudication 
Committee Members and data analysts will be blinded to the study treatment. All interpretation of 
study results will initially be done in a blinded manner by developing two interpretations of the 
results. One interpretation will assume treatment A is povidone-iodine, the other interpretation will 
assume it is CHG. Once the data interpretations for each assumption are finalized, the data will be 
unblinded and the correct interpretation will be accepted.18  
 
4.6 Description of the Interventions  
4.6.1 Initial Run-In Phase 
Prior to initiating patient recruitment, each clinical site will begin using their assigned pre-
operative antiseptic skin solution for eligible open fracture surgeries (run-in period) to ensure that 
acceptable compliance is met before initiating participant enrollment. Acceptable compliance 
during the run-in phase will be defined as at least 15 eligible open fracture patients with >90% of 
eligible patients receiving the allocated antiseptic solution or a minimum of one month in duration. 
The run-in phase may be extended up to 3 months, as deemed necessary by the CEO Methods 
Center. Study personnel at each clinical site will document compliance with administering the 
allocated treatment during the run-in phase and submit this weekly to the CEO Methods Center. 
Specifically, the weekly reports will include the total number of eligible open fracture patients 
operated on, the proportion who received the assigned pre-operative antiseptic skin solution, and 
the proportion who did not receive the assigned pre-operative antiseptic skin solution along with 
details about the deviations (e.g., name of attending surgeon, solution used, rationale for not using 
the assigned pre-operative antiseptic skin solution). This portion of the study protocol is for quality 
assurance during the initial implementation of the trial procedures.  Open fracture surgeries 
reviewed during the run-in phase will not be included in the trial.  Similarly, these patients will not 
be approached for informed consent and no individual patient-level data will be submitted. CEO 
Methods Center personnel will review the weekly reports with each of the clinical sites and 
develop strategies, as needed, to ensure acceptable compliance during the run-in phase. This 
weekly communication will prevent any delays in transitioning to the participant enrollment phase.  
 
4.6.2 First Intervention Phase 
Once the initial run-in phase is completed, participant recruitment will begin with the clinical sites 
continuing to use the same pre-operative antiseptic skin solution for all eligible open fracture 
surgeries for a two-month period. Patients will receive the initially allocated treatment solution for 
all of their open fracture management surgeries, including repeat planned surgeries, even if a 
planned subsequent surgery occurs during a recruitment period using the non-allocated solution. 
Participating clusters will ideally be able to enroll a minimum of 77 open fracture patients per 
treatment over the total study recruitment duration, and it is anticipated that most recruiting centers 
will exceed this minimum goal. Methods Center personnel will continue to monitor compliance 

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with the assigned pre-operative antiseptic skin solution over the enrollment phase and work 
collaboratively with the clinical sites to minimize cases in which a patient receives the incorrect 
solution. These monitoring activities will coincide with site-specific procedures to maintain 
compliance for all patients, even those requiring multiple surgical procedures. If an open fracture 
requires multiple surgeries and the correct solution is not applied at each procedure, the patient 
will remain in the study and be analyzed using the allocated solution (ITT principle). 
 
4.6.3 Second Intervention Phase  
Once the first intervention phase is completed, each site will crossover to the opposite study 
solution. There will be no run-in phase for the second solution and each site will need to develop 
local procedures to ensure a successful crossover. Example procedures to minimize carry-forward 
of first solution into the second solution phase include: 1) removing the bottles of the first solution 
from the orthopaedic operating rooms; 2) changing study posters and notifications within the 
operating rooms; and 3) performing the crossover during the middle of the week to provide a few 
days’ notice to the operating room staff and to avoid contamination of recent open fracture patients 
returning for repeat procedures (e.g., weekend admissions). The enrollment goals and procedures 
will mirror the first intervention phase. Methods Center personnel will continue to monitor 
compliance with the assigned pre-operative antiseptic skin solution over the enrollment phase and 
work collaboratively with the clinical sites to reduce the risk of contamination.  
 
4.6.4 Special Considerations for Ongoing Treatment Crossovers 
Treatment allocation will continue to alternate between the study solutions, as outlined above, for 
the remainder of study duration. Each intervention phase will be approximately 2 months in 
duration, as agreed upon by the local site and CEO Methods Center personnel. The duration may 
be modified to avoid crossovers on holidays, weekends, and other circumstances that could 
threaten a successful crossover. The expected recruitment duration for the trial is approximately 
24 months; however, some sites may have a shorter total recruitment duration (e.g., a participating 
site who joins the trial later, high volume clinical sites, etc.). The two-month enrollment periods 
will help account for seasonal variability in SSI incidence and their associated infectious 
organisms,19 as each crossover period will cover a season. In addition, for those clinical sites 
enrolling beyond 12 months, the distribution of recruitment periods for each solution may be 
seasonally matched by reversing the order of the alternating allocation after 12 months of 
recruitment.  
 
4.6.5 Evaluation of Site Performance and Removal of Clinical Sites 
After every two recruitment periods (approximately every four months), each site will be evaluated 
for continued participation in the trial. Sites with <90% of eligible patients receiving the allocated 
solution, differential adherence between study solutions, <95% follow-up of the primary outcome, 
<90% follow-up of the secondary outcome, incomplete data submission, or other threats to data 
quality or the validity of the study may be withdrawn from the trial. In the event a site is withdrawn, 
data collection will be completed for all enrolled participants and these data will be included in the 
final study analysis. 
 
4.6.6 Application of Pre-Operative Antiseptic Skin Solutions 
Each solution will be applied to the injured area in accordance with the Food and Drug 
Administration (FDA) and Health Canada approved manufacturer’s directions for use. While the 

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application and minimum drying time for both study solutions are very similar, local study 
personnel will provide standardized in-service (training) for orthopaedic surgeons, operating room 
technicians, and nurses at each participating hospital prior to the run-in phases for each of the two 
randomized interventions. This training should include reviewing the manufacturers’ directions 
for use to help minimize incorrect application at clinical sites that may not routinely use both 
solutions. In addition, the manufacturers may also provide demonstration videos and posters for 
continued refresher training for each solution.  
 
The study protocol will mandate the antiseptic skin solution to be used in each intervention phase 
(Sections 4.4, 4.6.1, 4.6.2, 4.6.3, and 4.6.4); however, the protocol will remain pragmatic to 
variability in other co-intervention steps performed during the entire pre-operative skin preparation 
process performed in the operating room. Based on individual surgeon preference, this often 
includes mechanically removing visible dirt or debris with a scrub brush, and/or cleaning the limb 
with isopropyl alcohol or antiseptic scrub solution. These additional skin preparation steps will be 
permitted provided that: 1) the final skin preparation step prior to surgical incision is the 
application of the allocated antiseptic solution; and, 2) participating surgeons continue to use the 
same skin preparation co-interventions in both intervention phases.  Co-interventions that contain 
the opposite active ingredient from the current intervention phase (e.g., using a chlorhexidine scrub 
brush during the povidone-iodine intervention phase, or conversely, using a povidone-iodine scrub 
during the chlorhexidine intervention phase) should be avoided; however, deviations from this 
recommendation will be permitted in order to maintain pragmatic flexibility of delivery and reflect 
real-world clinical practice.  The details of all operating room antiseptic co-interventions will be 
documented. 
 
The pragmatic nature of the cluster-randomized design will reduce the risk of crossovers between 
treatment groups because all consecutive patients during each recruitment period will receive the 
same treatment. Similarly, open fracture patients that require multiple planned surgeries for their 
injury will receive the same antiseptic skin solution during each subsequent procedure. Methods 
Center personnel will work with each of the clinical sites to develop strategies for minimizing 
crossovers. For example, for patients enrolled within 14 days of the anticipated end of a 
recruitment period or patients requiring multiple surgeries, study personnel will develop local 
procedures to identify these patients as study participants, and indicate the patient’s allocated 
antiseptic solution in the medical chart and CRFs.  
 
4.6.7 Povidone-Iodine Treatment 
The povidone-iodine solution will contain 10% povidone-iodine (1% free iodine) in purified water 
as the only active ingredient. Products that list other inactive ingredients, including alcohol, will 
be permitted. The brand of the solution will be left to the discretion of the clinical site, although 
Methods Center personnel will confirm that the chosen solution is acceptable. Acceptable brands 
include, but are not limited to, Betadine® [Purdue Products, L.P. Stamford, CT] and Scrub Care® 
[Cardinal Health, Dublin, OH]. Clinical site personnel will store and handle the povidone-iodine 
solution as per the manufacturers’ recommendations. Operating room personnel will apply the 
solution to the operative site as the final preoperative skin antisepsis preparation immediately prior 
to commencing surgical fixation. They will apply the solution as per manufacturer’s directions for 
use (e.g., technique of application, duration of application, drying time, drying techniques, 
replacement of draping, etc.).  

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4.6.8 Chlorhexidine Gluconate Treatment 
The CHG solution will contain 4% CHG in purified water as the only active ingredient. Products 
that list other inactive ingredients, including alcohol, will be permitted. The brand of the solution 
will be left to the discretion of the clinical site, although Methods Center personnel will confirm 
that the chosen solution is acceptable. Acceptable brands include, but are not limited to, Betasept® 
[Purdue Products, L.P. Stamford, CT] or Hibiclens® [Mölnlycke Health Care US LLC. Norcross, 
GA]. Clinical site personnel will store and handle the CHG solution as per the manufacturers’ 
recommendations. Operating room personnel will apply the solution to the operative site as the 
final preoperative skin antisepsis preparation immediately prior to commencing surgical fixation. 
They will apply the solution as per manufacturer’s directions (e.g., technique of application, 
duration of application, drying time, replacement of draping, etc.).  
 
4.7 Perioperative Co-Interventions 
To optimize the internal validity of the trial findings, key details of co-interventions known to 
influence the incidence of SSIs will be documented. Hospitals typically implement standard 
procedures to achieve quality process benchmarks designed to minimize SSIs. These benchmarks 
are outlined in several similar guidelines such as the Joint Commission’s Surgical Care 
Improvement Project 10 Core Measures to prevent SSI, the Society for Healthcare Epidemiology 
of America compendium to prevent SSI, and prevention guides from the Institute for Healthcare 
Improvement and the Association of periOperative Registered Nurses. While these guidelines 
mandate core benchmark processes to minimize SSI, it is not practical or generalizable for the trial 
protocol to standardize the steps taken or co-interventions performed to achieve these core 
measures, since each participating hospital will already have their own implemented procedures. 
This is the primary rationale for the cluster-crossover design, in which each participating hospital 
will act as its own control for the effect of co-interventions. Therefore, four key approaches to 
account for and limit the potential differential application of co-interventions during the study 
periods will be performed: 1) study periods for each intervention are kept relatively short to 
improve the likelihood that newly implemented co-interventions will be equally distributed across 
both treatment solutions; 2) encourage participating hospitals not to make changes to their existing 
infection prevention interventions during the study periods; 3) document the co-interventions 
being used in the hospitals throughout the study periods; and 4) record any changes in co-
interventions that do occur if mandated by a participating hospital’s administration. To this end, a 
monitoring tool containing a list of commonly applied prophylactic co-interventions being used at 
the participating clinical sites will be completed every four months to document any changes to 
their infection prevention strategies during the study period. 
 
4.8 Outcome Measures 
4.8.1 Primary Outcome  
The primary outcome is SSI, guided by the CDC’s National Healthcare Safety Network reporting 
criteria (2017),5 which includes superficial incisional SSI within 30 days and deep incisional or 
organ/space SSI within 90 days of fracture surgery (Table 3). Since the management of some open 
fractures may have more than one operative procedure as part of an intentionally staged surgical 
plan (e.g., multiple irrigation and debridements, wound closures, temporary stabilization surgeries, 
definitive fixation surgery), the primary outcome will include any SSI event from the date of open 
fracture to the end of the 30- and 90-day post-operative surveillance periods from their definitive 

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fracture management surgery. For participants with multiple open fracture regions, the date of the 
definitive fracture management surgery will be matched to the open fracture region with the SSI. 
 
Table 3: CDC Surgical Site Infection Criteria 
Outcome 
Description 
Superficial 
Incisional 
SSI 
Date of event for infection occurs from the date of fracture to 30 days after the definitive fracture 
management surgery (where day 1 = the procedure date) 
AND 
involves only skin and subcutaneous tissue of the incision 
AND 
patient has at least one of the following: 
a. 
purulent drainage from the superficial incision. 
b. organisms identified from an aseptically-obtained specimen from the superficial 
incision or subcutaneous tissue by a culture or non-culture based microbiologic 
testing method which is performed for purposes of clinical diagnosis or 
treatment (e.g., not Active Surveillance Culture/Testing [ASC/AST]). 
c. 
superficial incision that is deliberately opened by a surgeon, attending physician 
or other designee and culture or non-culture based testing is not performed. 
              AND 
patient has at least one of the following signs or symptoms: pain or tenderness; 
localized swelling; erythema; or heat. 
d. diagnosis of a superficial incisional SSI by the surgeon or attending physician 
or other designee.  
The following do not qualify as criteria for meeting the definition of superficial SSI: 
• 
Diagnosis/treatment of cellulitis (redness/warmth/swelling), by itself, does not meet 
criterion “d” for superficial incisional SSI. Conversely, an incision that is draining or that 
has organisms identified by culture or non-culture based testing is not considered a 
cellulitis. 
• 
A stitch abscess alone (minimal inflammation and discharge confined to the points of 
suture penetration). 
• 
A localized stab wound or pin site infection- Such an infection might be considered either 
a skin (SKIN) or soft tissue (ST) infection, depending on its depth, but not an SSI  
Note: A laparoscopic trocar site for an operative procedure is not considered a stab wound. 
• 
An infected burn wound is classified as BURN and is not an SSI. 
Deep 
Incisional 
SSI 
The date of event for infection occurs from the date of fracture to 90 days after the definitive 
fracture management surgery (where day 1 = the procedure date)  
AND 
involves deep soft tissues of the incision (e.g., fascial and muscle layers) 
AND 
patient has at least one of the following: 
a. 
purulent drainage from the deep incision. 
b. a deep incision that spontaneously dehisces, or is deliberately opened or aspirated by a 
surgeon, attending physician or other designee, and organism is identified by a culture or 
non-culture based microbiologic testing method which is performed for purposes of 
clinical diagnosis or treatment (e.g., not Active Surveillance Culture/Testing 
[ASC/AST]) or culture or non-culture based microbiologic testing method is not 
performed 
            AND 
patient has at least one of the following signs or symptoms: fever (>38°C); localized 
pain or tenderness. A culture or non-culture based test that has a negative finding does 
not meet this criterion. 
c. 
an abscess or other evidence of infection involving the deep incision that is detected on 
gross anatomical or histopathologic exam, or imaging test 
Organ/Space 
SSI 
Date of event for infection occurs from the date of fracture to 90 days after the definitive fracture 
management surgery (where day 1 = the procedure date)  

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Outcome 
Description 
AND 
infection involves any part of the body deeper than the fascial/muscle layers, that is opened or 
manipulated during the operative procedure 
AND 
patient has at least one of the following: 
a. 
purulent drainage from a drain that is placed into the organ/space (e.g., closed 
suction drainage system, open drain, T-tube drain, CT guided drainage) 
b. organisms are identified from an aseptically-obtained fluid or tissue in the 
organ/space by a culture or non-culture based microbiologic testing method 
which is performed for purposes of clinical diagnosis or treatment (e.g., not 
Active Surveillance Culture/Testing [ASC/AST]). 
c. 
an abscess or other evidence of infection involving the organ/space that is 
detected on gross anatomical or histopathologic exam, or imaging test evidence 
suggestive of infection. 
AND 
meets at least one criterion for a specific organ/space infection site listed in Table 3 of the CDC 
Procedure-associated Module (summarized in Table 4 below).5 These criteria are found in the 
Surveillance Definitions for Specific Types of Infections chapter.19 
*The CDC criteria has been modified to include all definitive fracture management surgeries, as opposed to including 
only National Healthcare Safety Network procedures that require infection reporting.  
 
The CDC criteria for classifying SSIs will be followed. If multiple tissue levels are involved in the 
infection, the type of SSI (superficial incisional, deep incisional, or organ/space) reported will 
reflect the deepest tissue layer involved in the infection during the surveillance period. The date of 
event will be the date that the patient met criteria for the deepest level of infection: 1) Report 
infection that involves the organ/space as an organ/space SSI, whether or not it also involves the 
superficial or deep incision sites and 2) Report infection that involves the superficial and deep 
incisional sites as a deep incisional SSI. The most relevant National Healthcare Safety Network 
Organ/Space SSI classifications are summarized in Table 4.  
 
Table 4: Relevant Organ/Space SSI Sites 
Organ/Space SSI 
BONE 
Osteomyelitis 
JNT 
Joint or bursa infection 
PJI 
Prosthetic joint infection 
 
 
All reported SSIs will be reviewed independently by an infection preventionist nurse and an 
orthopaedic surgeon who are members of the Adjudication Committee. Briefly, they will complete 
the review by examining all relevant information to determine if the SSI meets the CDC criteria 
of a superficial incisional SSI, deep incisional SSI, or organ/space SSI. The Committee will reach 
consensus on all reviewed SSIs. A hospital epidemiologist and infectious disease physician who 
are members of the Adjudication Committee will be available to provide guidance as needed.  All 
members of the Adjudication Committee will be blinded to the treatment allocation.  
 
4.8.2 Secondary Outcome 
The secondary outcome is unplanned fracture-related reoperation within 12 months of the open 
fracture. This outcome has been used in previous open fracture trials and is defined as any 
unplanned surgery that occurred from the time of injury to 12 months post-injury that is associated 
with an infection at the operative site or contiguous to it, a wound-healing problem, or a fracture 
delayed union or nonunion. Common examples include any unplanned: 1) irrigation and 

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debridement of surgical incisions or open fracture wounds due to infections or wound healing 
problems; 2) revision wound closure for dehiscence; 3) soft tissue coverage procedure for infected 
or necrotic wound; 4) fracture delayed union or nonunion surgery (such as bone grafting or implant 
exchange); and 5) reoperation for hardware or prosthesis failure due to infection or bone-healing 
problems. Removal of hardware for soft tissue prominence or periprosthetic fracture are common 
examples of reoperations that will not be considered outcome events. Two orthopaedic surgeons 
who are members of the Adjudication Committee will independently review all reported 
unplanned fracture-related reoperations to determine if they meet the criteria for being a study 
event. The Committee will reach consensus on all reviewed unplanned fracture-related 
reoperations. 
 
4.8.3 Exploratory Outcomes 
Two exploratory definitions of infection will be used for sensitivity analyses of the primary 
comparison. The first exploratory outcome is fracture-related infection (FRI) within 12 months of 
the open fracture, defined by the confirmatory criteria for FRI outlined in a 2018 consensus 
definition.20  The FRI criteria has been selected as an exploratory outcome because the CDC 
criteria has been criticized for failing to adequately account for the complexities of infections in 
traumatic fractures.20,21 The FRI criteria attempts to improve upon the ability to detect infections 
specifically in fracture patients; however, this definition of FRI has not been fully validated or 
widely adopted.    
 
The confirmatory criteria include the presence of one or more of the following signs/symptoms:  
1) Fistula, sinus or wound breakdown (with communication to the bone or the implant). 
2) Purulent drainage from the wound or presence of pus during surgery. 
3) Phenotypically indistinguishable pathogens identified by culture from at least two separate 
deep tissue/implant (including sonication-fluid) specimens taken during an operative 
intervention. In case of tissue, multiple specimens (3) should be taken, each with clean 
instruments (not superficial or sinus tract swabs). In cases of joint effusion, arising in a 
joint adjacent to a fractured bone, fluid samples obtained by sterile puncture may be 
included as a single sample. 
4) Presence of microorganisms in deep tissue taken during an operative intervention, as 
confirmed by histopathological examination using specific staining techniques for bacteria 
or fungi.  
 
The second exploratory outcome is SSI using the CDC criteria within 12 months of the open 
fracture.  This secondary outcome will use the same diagnostic CDC reporting criteria for the 
primary outcome (Tables 3 and 4); however, the timeframe for this outcome will be expanded to 
include all SSIs that occur within 12 months of open fracture.   Similar to the rationale for using 
the FRI outcome, and the recommendations for a minimum of 12 months follow-up for orthopaedic 
fracture outcomes22, this expanded timeframe will detect infections that occur beyond the standard 
CDC surveillance reporting periods.  This modification of the CDC reporting periods has been 
used in previous orthopaedic fracture trials.7,23  
 
An infection preventionist nurse and an orthopaedic surgeon member of the Adjudication 
Committee will review all reported SSIs to determine if they meet the FRI confirmatory criteria 
and / or the CDC criteria following the processes described above (see Section 4.8.1).   

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4.8.4 Data Collection and Participant Follow-up 
After obtaining informed consent, study personnel will record the baseline data on the study CRFs. 
They will obtain this information directly from the participant or proxy, from the participant’s 
medical chart, and the participant’s treating orthopaedic surgeon and other health care providers. 
Data collection points include patient characteristics and injury details such as age, gender, 
comorbidities, mechanism of injury, socioeconomic status, and other injuries. Study personnel will 
also record the characteristics of up to three open fracture regions including the location, fracture 
severity, size of the wound, and degree of soft tissue injury using the Gustilo classification.8,17,24   
 
Surgical data and in-hospital data will be collected throughout the participant’s hospital stay. 
Detailed information will be collected regarding the surgical management of the open fracture(s), 
including the time to irrigation and debridement. For each open fracture region, study personnel 
will record the use of staged debridements, the presence or lack of skin closure between 
debridements, and the use of local antibiotics at the wound. The method(s) of initial and final 
fracture management will also be captured. Lastly, study personnel will record the use of negative 
pressure wound therapy for open wounds or in the presence of open wounds surgically closed. 
These treatment decisions are hypothesized to be associated markers of injury severity and 
potential confounders of the study interventions. 
 
Study participants will be followed at 6 weeks, 3 months, 6 months, 9 months, and 12 months from 
their fracture.  SSIs and unplanned fracture-related reoperations will be identified at the time of 
diagnosis/occurrence and/or during each participant’s clinical assessment and medical record 
review that will occur during their routine outpatient clinic visits (Table 2). Detailed information 
on the SSI including the date of diagnosis, patient signs and symptoms, culture test results, method 
of treatment(s), and date of resolution will be collected. Study personnel will also record details 
about the participants’ reoperations on the CRFs (e.g., date of reoperation, type of procedure, 
reason for procedure, etc.). In cases where the participant does not return to the clinic, study 
personnel will contact the participant by telephone, text, email, standard mail, and/or will review 
their medical record for any SSIs, and unplanned fracture-related reoperations. If the patient 
reports being treated at another hospital, study personnel will obtain the medical records from the 
other hospital. We have used this approach in our other multi-center trials (e.g., SPRINT, TRUST, 
FLOW, FAITH, HEALTH, etc.).7,23,25–27  
 
To ensure research participant safety, serious adverse events (SAEs) will be documented at each 
follow-up visit and promptly submitted to the Methods Center and the local or central Institutional 
Review Board (IRB) or Research Ethics Board (REB) as per the required reporting processes.  
 
Several strategies may be used to maximize follow-up including: 1) at the time of enrollment, each 
participant will provide their own telephone number, as well as the name and address of a primary 
care physician, and the names and phone numbers of three people at different addresses with whom 
the participant does not live with and who are likely to be aware of the participant’s whereabouts; 
2) participants will receive a reminder card upon discharge for their next follow up visit by the 
clinical site study personnel; 3) participants will receive text message reminders; 4) follow-up will 
coincide with normal surgical fracture clinic visits; and 5) if a participant refuses or is unable to 
return for the follow-up assessment, study personnel will determine his/her status with regard to 

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major study outcomes by telephone, text, or email contact with the participant or the provided 
alternate contacts. Given these are standard of care visits and the participants will be receiving 
ongoing orthopaedic care for their acute fractures, minimal loss to follow-up is expected. Using 
these techniques, we expect greater than 95% follow-up at 3 months and 90% follow-up at 12 
months post-fracture. 
 
Participants will not be deemed lost to follow-up until the 12-month visit is overdue and all 
attempts to contact the participant have been exhausted. Participants will not be withdrawn from 
the study if the study protocol was not adhered to (e.g., allocated treatment not received, missed 
follow-up visits, etc.). The reasons for participants being withdrawn from the study will be 
documented (e.g., withdrawal of consent or lost to follow up). 
 
5.0 STATISTICAL PLAN  
 
5.1 Sample Size Determination 
The overall objective of the trial is to determine the most effective aqueous pre-operative antiseptic 
skin solution for use during open fracture management. This will be achieved by comparing the 
effectiveness of 10% povidone-iodine versus 4% CHG surgical skin preparations. The primary 
outcome is the occurrence of SSI, as per the adapted CDC criteria (Table 3).5 The secondary 
outcome is the occurrence of unplanned fracture-related reoperations within 12 months of injury. 
The sample size was calculated for the primary comparison between proportions of patients with 
SSI in each treatment group; however, it is expected that this estimate will also provide adequate 
power for the secondary outcome (unplanned fracture-related reoperation) because the baseline 
incidence (13%) and effect size for the reoperation outcome are expected to be similar to the SSI 
estimates.7  
 
Assuming an ITT principle for the analysis, the sample size was calculated based on a cluster 
crossover design with the cluster as the unit of randomization and the patient as the unit of analysis. 
For complex study designs, such as a cluster-randomized crossover trial, simple formulas to 
calculate sample size or power may not capture the expected variability from the observed data.28 
Simulation methods were used to obtain empirical power calculations based on a feasible number 
of recruiting clusters and the expected number of open fracture patients.28 The simulation estimates 
are designed to detect a difference between the treatment groups, accounting for between hospital 
variability inherent to a cluster-crossover trial design. We have assumed that the povidone-iodine 
solution will achieve a 0.65 risk ratio for SSI with a 12.5% SSI baseline incidence.1,3,7 This 
represents approximately a 4% absolute risk reduction in SSI and reoperation. This effect was 
deemed more conservative than data reported by Swenson et al. and was consistent with feasible 
recruitment goals.4   
 
Recent simulation data suggest that increasing the number of period crossovers can increase the 
statistical power of a given sample size.29 To ensure the most conservative sample size estimate, 
we have based our sample size assumptions using a single crossover, 2 period design. The initial 
power estimate assumed 10 recruiting clusters, a 10% loss to follow-up rate,7 and applying the 
between-cluster variance of 0.095 observed in the FLOW trial.  Based on enrollment of a minimum 
of 1,540 open fracture patients, greater than 80% power would be achieved. Subsequent to the 
initial power calculations, the early trial experience demonstrated a need to increase the number 

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of clusters to obtain a feasible recruitment pace. As a result, a minimum of 12 clusters will enroll 
participants into Aqueous-PREP. The increase in clusters results in a marginal increase in power 
(~2%).   
 
Table 5 below outlines the summary of the initial sample size assumptions that yield 80% power 
to detect difference between the treatments. These sample size estimates are rounded up to the 
nearest multiple of 20 to ensure balance among the clinical sites and two interventions. 
 
Table 5: Sample Size Assumptions 
Baseline SSI Risk 
10% Povidone-
Iodine Risk Ratio 
10% Povidone-
Iodine Odds Ratio 
Sample Size 
Sample Size Increased 
by 10% 
10.0% 
0.62 
0.59 
1600 
1760 
10.0% 
0.65 
0.63 
1960 
2100 
10.0% 
0.67 
0.65 
2200 
2420 
10.0% 
0.70 
0.68 
2600 
2860 
12.5% 
0.62 
0.59 
1300 
1440 
12.5% 
0.65 
0.62 
1400 
1540 
12.5% 
0.67 
0.64 
1600 
1760 
12.5% 
0.70 
0.67 
1800 
1980 
14.0% 
0.62 
0.58 
1200 
1320 
14.0% 
0.65 
0.61 
1300 
1440 
14.0% 
0.67 
0.64 
1500 
1660 
14.0% 
0.70 
0.67 
1800 
1980 
Note: *Between cluster ICC = 0.028; Between cluster variance* = 0.095; Between period variance = 0; Number of 
clusters = 10; Number of periods = 2; Alpha = 0.05 
 
5.2 Statistical Methods 
5.2.1 Analysis Plan Overview 
A detailed statistical analysis plan will be published prior to the completion of the trial.  The 
analysis and reporting of the results will follow the CONSORT guidelines for reporting of both 
pragmatic trials30 and cluster-randomization trials.31 The process of patient enrollment and flow 
throughout the study will be summarized using a flow-diagram. Patient demographics and baseline 
outcome variables will be summarized using descriptive summary measures expressed as mean 
(standard deviation) or median (interquartile range) for continuous variables depending on the 
distribution, and number (percent) for categorical variables.32 An ITT principle will be adopted to 
analyze all outcomes and the unit of analysis will be the individual patients. Missing data will be 
assumed to be missing at random and will be handled with multiple imputation.33,34 
 
The primary analysis will compare the treatment groups on the SSI outcome and the secondary 
analysis will compare the unplanned fracture-related reoperation outcome. The secondary 
comparison will be conducted in accordance with best practice guidelines for secondary analyses. 
For all models, the results will be expressed as relative measure of effect (odds, risk, or hazard 
ratios) and corresponding two-sided 95% confidence intervals.  
   
5.2.2 Analysis of the Study Outcomes 
Adopting an ITT principle, multilevel regression models will be used. Correlation structures will 
be fit based on the observed between cluster and between period effects. A robust sandwich 
estimator will be used to analyze the primary and secondary outcomes. 

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For the primary outcome, SSI will be the dependent variable and the antiseptic solution (treatment 
group) will be the independent variable. For the secondary outcome, unplanned fracture-related 
reoperation will be the dependent variable and the antiseptic solution (treatment group) will be the 
independent variable. For both analyses, multiple imputation will be used to handle missing data.34  
 
As the optimal methods for analyzing cluster crossover trials continue to evolve, the final statistical 
modeling technique to be used will be determined in accordance with contemporary best practices 
prior to the completion of participant follow-up. A separate Statistical Analysis Plan will be 
developed prior to study closeout. Table 6 below shows a summary of the study outcomes, 
corresponding hypotheses, and currently proposed methods of analysis. 
 
Table 6: Summary of Outcome Analysis Plan 
Objective 
Outcome 
Hypothesis 
Method of 
Analysis 
Name 
Type 
To determine the effect of 10% povidone-iodine 
versus 4% CHG pre-operative antiseptic skin 
solutions on the incidence of SSI and unplanned 
fracture-related reoperation. 
SSI 
Binary 
10% 
povidone-
iodine will be 
more effective 
than CHG 
 Multi-level 
regression 
model 
Unplanned 
Fracture-
Related 
Reoperation 
Binary 
10% 
povidone-
iodine will be 
more effective 
than CHG 
 Multi-level 
regression 
model 
Note: CHG = 4% chlorhexidine gluconate; SSI = Surgical Site Infection 
 
5.2.3 Subgroup Analyses 
Three subgroup analyses will be performed. The primary subgroup will be defined by the severity 
of open fracture (Gustilo-Anderson type I or II versus III).8 Secondary subgroups will include: i) 
upper extremity versus lower extremity open fractures; and ii) none, minimal, or surface 
contamination versus contamination embedded in bone or deep soft tissues.17 These analyses will 
be performed by comparing the effect estimates in both groups (interaction effect). We hypothesize 
that effect will differ by subgroup. These analyses will be approached and reported in accordance 
with best practices and guidelines for subgroup analyses.35–38 Table 7 below shows a summary of 
the subgroup analysis objectives, corresponding outcomes, hypotheses, and methods of analysis. 
 
Table 7: Summary of Subgroup Analysis Plan 
Objective 
Outcome 
Hypothesis 
Method of 
Analysis 
Name 
Type 
Primary 
Severity of open fracture 
(Gustilo-Anderson Type I 
or II vs. Type III) 
SSI /  
Unplanned 
Fracture-
Related 
Reoperation 
Binary 
10% povidone-iodine will be 
associated with a larger reduction 
in odds for SSI and reoperation 
than CHG in more severe fractures 
Interaction of 
treatment by 
subgroup 
Secondary 
Upper extremity vs. lower 
extremity fractures 
SSI /  
Binary 
10% povidone-iodine will be 
associated with a larger reduction 
in odds for SSI and reoperation 
Interaction of 
treatment by 
subgroup 

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Unplanned 
Fracture-
Related 
Reoperation 
than CHG in lower extremity 
compared to upper extremity 
fractures 
None, minimal, or surface 
wound contamination vs. 
embedded wound 
contamination 
SSI /  
Unplanned 
Fracture-
Related 
Reoperation 
Binary 
10% povidone-iodine will be 
associated with a larger reduction 
in odds for SSI and reoperation 
than CHG in embedded 
contaminated wounds compared to 
wounds with no, minimal or 
surface contamination  
Interaction of 
treatment by 
subgroup 
Note: CHG = 4% chlorhexidine gluconate; SSI = Surgical Site Infection 
 
5.2.4 Sensitivity Analyses 
Assessment of the sensitivity or robustness of the findings to the key assumptions is essential in 
trials. The following sensitivity analyses may be conducted to explore the effects of alternative 
analysis models, alternative missing data approaches, balancing prognostic imbalance, as-treated 
analyses, variability in co-interventions, and alternative definitions of SSI.   
 
1) Using different analysis models: There are several methods for analyzing cluster randomized 
crossover trials.34,39 Therefore, our sensitivity analyses will explore alternative multi-level models 
with different correlation structures for the error.35,39,38  
 
2) Different methods of handling missing data: There are several methods of handling missing data 
in trials.39 Multiple imputation assumes that the data are missing at random—an assumption that 
is not verifiable in practice. Other imputation methods will be used such as worst case scenario to 
impute missing data and assess the robustness of the results.40 For the worst case scenario analysis, 
we will assume that a random proportion of participants lost to follow-up experienced a study 
event. For this sensitivity analysis, the proportion assumed to experience a study event will be 
equivalent to the upper confidence interval of the observed pooled event rate for each study 
outcome.  
 
3) Adjusted analyses for prognostic imbalance: We will also perform sensitivity analyses that 
assume prognostic imbalance between the two treatment groups based on the following key 
variables known to be risk factors for SSI or reoperation after open fracture: Gustilo fracture type, 
lower extremity fracture, wound contamination, time from injury to first debridement, antiseptic 
wound dressing in the emergency department, method of fixation, wound closure at initial 
debridement, age, work-related injury, and employment status.16 Adjusted analyses including the 
above risk factors and treatment group as independent variables will be performed for the SSI and 
reoperation outcomes.  
 
4) As-treated analyses: The proportion of surgical procedures receiving the incorrect, non-
allocated antiseptic solution will be reported. “As-treated” sensitivity analyses will be performed 
using the solution received as the independent variable.  For participants that were treated in a 
single open fracture surgery, they will be analyzed using the antiseptic solution received.  For 
participants who received multiple open fracture surgeries, two analyses will be performed.  First, 
the antiseptic solution used in their last surgery prior to a study outcome event will define their 
study treatment.  For the second analysis, the antiseptic solution received in the majority of their 

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fracture surgeries will define their study treatment.  Participants who were treated with multiple 
open fracture management surgeries, but received equal exposure to both treatment solutions (e.g. 
one surgery with CHG and one surgery with iodine), will be analyzed within their originally 
allocated treatment group.   
 
5) Co-intervention variability: Selective censoring of one or more clusters and / or treatment 
periods will be performed to further explore between-cluster and between-period variability 
identified in the primary and secondary outcome comparisons. These analyses will be used to 
explore the robustness of the study conclusions in the context of measured practice variations in 
co-interventions that differ between participating sites and / or evolve over the duration of the 
study recruitment. Results that are sensitive to the removal of a cluster(s) and / or period(s) will be 
reported, along with potential clinical hypotheses that are supported by the measured clinical 
practice variation.   
 
6) Exploratory SSI definitions: The above analyses (See Section 5.2.2) will be repeated for the 
primary comparison using the FRI outcome and the CDC definition within 1 year of injury to 
determine if the study conclusions are sensitive to alternative definitions of SSI.  
 
Table 8 below shows a summary of the objectives, corresponding outcomes, hypotheses, and 
methods for each potential sensitivity analysis.   
 
Table 8: Summary of Sensitivity Analysis Plan 
 
Objective 
Outcome 
Hypothesis 
Method of Analysis 
Name 
Type 
1 
Different analysis 
models 
SSI / 
Reoperation 
Binary 
10% povidone-
iodine will be more 
effective than CHG 
Multi-level regression 
models with different 
correlation structures 
2 
Different missing data 
approach 
SSI / 
Reoperation 
Binary 
10% povidone-
iodine will be more 
effective than CHG 
Multi-level regression 
models with missing 
data imputed using 
worst-case scenario 
3 
Baseline prognostic 
imbalance 
SSI / 
Reoperation 
Binary 
10% povidone-
iodine will be more 
effective than CHG 
Multi-level regression 
models with prognostic 
variables & treatment 
group 
4 
As-treated analysis 
SSI / 
Reoperation 
Binary 
10% povidone-
iodine will be more 
effective than CHG 
Multi-level regression 
models using “as 
treated” treatment group 
5 
Co-intervention 
variability 
SSI / 
Reoperation 
Binary 
Cluster- and period-
variability is related 
to co-interventions 
Censoring of cluster(s) 
and/or period(s) with 
differences in co-
interventions 
6 
Exploratory 
SSI definitions 
FRI / 
CDC SSI within 
1 year 
Binary 
10% povidone-
iodine will be more 
effective than CHG 
Multi-level regression 
models 
Note: CHG = 4% chlorhexidine gluconate; SSI = Surgical Site Infection; FRI = Fracture Related Infection; CDC = 
Centers for Disease Control and Prevention. 

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5.2.5 Interim Analysis 
No formal interim analyses are planned and the trial will not be stopped early for benefit. The Data 
and Safety Monitoring Committee (see Section 7.5.5) will review frequent safety reports and will 
collectively make judgments on the strength of evidence and the absolute magnitude and 
seriousness of any safety signals.41  The Data and Safety Monitoring Committee may make 
recommendations regarding the trial. 
 
6.0 DATA MANAGEMENT 
 
6.1 Case Report Forms and Data Transmission 
Clinical sites will be provided with the trial CRFs prior to initiation of enrollment. Research 
personnel at each clinical site will submit the required data, as detailed on the CRFs, to the Methods 
Center using the REDCap Cloud electronic data capture system. Clinical site personnel will 
receive a unique login and password for the REDCap Cloud system and will be able to view and 
modify data for participants recruited at their clinical site.  
 
6.2 Data Integrity 
The REDCap Cloud system uses a variety of mechanisms for checking data at the time of entry 
including skip logic, range checks, and data type checks. Upon receipt of new data, the personnel 
at the Methods Center will query all missing, implausible, or inconsistent data. Clinical site 
personnel will be able to review of open queries in the system and will be required to respond 
promptly.   
 
7.0 ETHICS AND DISSEMINATION 
 
7.1 Research Ethics Approval 
The McMaster University Methods Center and all participating clinical sites will receive REB or 
IRB approval prior to commencing participant enrollment. A central IRB and local IRBs/REBs 
will be used based on clinical site logistics. Prior to local commencement of the study, each clinical 
site will provide the Methods Center with a copy of their ethics approval. 
 
7.2 Consent 
In many cluster randomized comparative effectiveness trials, a waiver of consent is obtained from 
the IRB of Record.  The rationale for the waiver of consent is that all patients will receive 
treatments that are effective and within standards of care, they will receive one of the study 
treatments as part of their routine care regardless of study participation, the data collection is 
minimal and obtained from the patient’s medical records, the trial involves no more than minimal 
risk to the patient, and that the waiver of consent will not adversely affect the rights and welfare 
of the patient. Most of these concepts apply to the current trial, as the Aqueous-PREP trial is 
comparative effectiveness research where patients will receive one of the preoperative antiseptic 
skin solutions regardless of their participation in the study. Additionally, patients are not included 
in the decision-making process for the choice of antiseptic preparation solution, and, in most 
situations, they are not even aware of which solution is used.  However, in contrast to many cluster 
randomized crossover trials, Aqueous-PREP study personnel will need to contact participants 
directly to collect baseline and outcome data, as this information cannot be reliably obtained from 

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the patients’ medical records.  Therefore, study personnel will obtain informed consent from 
patients prior to data collection.  This consent process will allow study participants to be informed 
about the study rationale and provide consent for ongoing surveillance and data collection.   
 
To increase enrollment and to avoid missing potential study participants, the consent process may 
take place up to 3 weeks post-fracture.  Consultation during the study design phase with IRB 
members and patient advisors confirmed the acceptability of this flexible approach, where consent 
may be obtained after the intervention. The primary rationale for allowing consent after the 
intervention is consistent with the waiver of consent principles outlined above, but in addition, the 
patient and IRB stakeholders recognized that obtaining consent prior to the patient’s first surgery 
could add undue decision making stress to a patient who is awaiting surgical management of a 
serious extremity injury; allowing consent after their surgery would likely facilitate an improved 
consent process.  
 
The consent process will typically take place in the patient’s hospital room or in the outpatient 
fracture clinic, either before or after the patient has had surgery(ies) to manage their open fracture. 
If the patient is unable to provide informed consent (e.g., due to their injury, language restrictions) 
within 3 weeks of their fracture, informed consent will be obtained from their proxy. In addition, 
if a patient has been discharged from hospital prior to being invited to participate in the study, a 
delegated member of the clinical care team may obtain their consent by telephone, as approved by 
the IRB of Record.   
 
To obtain informed consent, delegated study personnel should follow the below procedures: 
• Present study information in a manner that is understandable to the potential 
participant/proxy. 
• Discuss the study with the potential participant/proxy and answer any questions he or 
she asks. 
• Allow the potential participant/proxy an opportunity to discuss participation with their 
family, friends, or family physician, if desired.  
• Confirm that the participant/proxy understands the risks and benefits of participating 
in the study and that their participation is voluntary. 
• Complete and obtain signatures for informed consent form and obtain contact 
information from the participant/proxy. 
• Provide /send the participant/proxy with a paper/electronic copy of the signed consent 
form. 
Consent may be obtained electronically or using pen and paper consent forms, as approved by the 
IRB of Record.   
The process of obtaining and documenting informed consent will be completed in accordance with 
local Good Clinical Practice recommendations. Consent procedures and forms, and the 
communication, transmission and storage of patient data will comply with the IRB of Record and 
Department of Defense requirements for compliance with The Health Insurance Portability and 
Accountability Act.  
 
Upon providing informed consent, study participants will be followed for 12 months from their 
fracture. Given the short follow-up time, the need for a regular reassessment of consent will not 
apply; however, participants may withdraw their consent at any time.  

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7.3 Confidentiality 
Information about study participants will be kept confidential and will be managed in accordance 
with the below rules: 
• All study-related information will be stored securely. 
• All study participant information will be stored in locked file cabinets and accessible 
only to study personnel. 
• All paper and electronic CRFs will be identified only by a coded participant number 
and initials. 
• All databases will be password protected. 
 
In the event that a participant revokes authorization to collect or use personal health information, 
the clinical site retains the ability to use all information collected prior to the revocation of 
participant authorization. For participants who have revoked authorization to collect or use 
personal health information, attempts should be made to obtain permission to collect at least vital 
status (i.e., primary outcome data) at the end of their scheduled study period. 
 
7.4 Protocol Amendments 
Any amendments to the study protocol which may affect the conduct of the study or the potential 
safety of or benefits to participants (e.g., changes to the study objectives, study design, sample 
size, or study procedures) will require a formal amendment to the protocol. Any protocol 
amendments will be approved by the Principal Investigators and will require approval by the 
McMaster University REB, the Central IRB, local IRBs/REBs, as well as the funders (as needed). 
Clinical sites will also be required to submit amendment requests to their IRB of Record to obtain 
approval for the amendment and to provide the Methods Center with a copy of this approval. 
Administrative changes (e.g., minor corrections or clarifications that have no effect on the way the 
study is conducted) will not need to undergo a formal amendment process. 
 
7.5 Adverse Event Reporting and Definitions 
7.5.1 Serious Adverse Event (SAE) 
A SAE is any adverse event that is any of the following: 
• Fatal 
• Life threatening 
• Requires or prolongs hospital stay 
• Results in persistent or significant disability or incapacity 
• A congenital anomaly or birth defect 
• An important medical event  
 
7.5.2 Unanticipated Problems Resulting in Risk to Participant or Others 
Any incident, experience, or outcome that meets the following criteria: 
• Unexpected in nature, severity, or frequency (e.g., not described in study-related 
documents such as the ethics-approved protocol or consent form, etc.). 
• Related or possibly related to participation in the research (i.e., possibly related means 
there is reasonable possibility that the incident experience or outcome may have been 
caused by the procedures involved in the research). 

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• Suggests that the research places participants or others at greater risk of harm (including 
physical, psychological, economic, or social harm).  
 
7.5.3 Clinical Site Reporting: Notifying the Methods Center 
Clinical sites are responsible for reporting SAEs to the Methods Center via the REDCap Cloud 
system. Significant new information on ongoing SAEs should also be provided promptly to the 
Methods Center via the REDCap Cloud system. Unanticipated problems resulting in risk to 
participants or others are also to be reported promptly to the Methods Center. 
 
7.5.4 Clinical Site Reporting – IRB and REB 
Clinical sites are responsible for reporting SAEs and unanticipated problems resulting in risk to 
participants or others to their local REB/IRB or the Central IRB in accordance with local reporting 
requirements. Copies of each report and documentation of ethic board notification and receipt will 
be kept in the clinical site’s study file. 
 
7.5.5 Safety Monitoring 
As per the FDA guidance document the Establishment and Operation of Clinical Trial Data 
Monitoring Committees for Clinical Trial Sponsors, a Data and Safety Monitoring Committee will 
oversee the safety of the trial participants and the overall conduct of the trial. The members of the 
Data and Safety Monitoring Committee will include two orthopaedic surgeons, an infectious 
disease expert, and a biostatistician. One orthopaedic surgeon will act as the Chair of the 
Committee. The Data and Safety Monitoring Committee will be responsible for safeguarding the 
interests of study participants, assessing the safety and efficacy of study procedures, and for 
monitoring the overall conduct of the study. The Data and Safety Monitoring Committee will 
frequently review enrollment and demographic summaries, listings of protocol deviations, and 
summaries and listings of SAEs. They will advise the Principal Investigators and study team on 
any concerns related to participant safety and trial conduct, and will make recommendations for 
the study to continue as designed, for study termination, for study continuation with major or minor 
modifications, or temporary suspension of enrollment until some uncertainty is resolved. We will 
develop a Data and Safety Monitoring Committee charter to guide the process. 
 
7.6 Dissemination Policy 
Results from the study will be submitted for publication regardless of whether there are significant 
findings. Every attempt will be made to ensure that the amount of time between completion of data 
collection and release of study findings are minimized. 
 
8.0 DEPARTMENT OF DEFENSE REPORTING REQUIREMENTS 
The following are the minimum reporting requirements with which the Principal Investigators 
must comply. The protocol will not be initiated at Department of Defense-funded clinical sites 
until written notification of approval of the research project is issued by the United States Army 
Medical Research and Materiel Command (USAMRMC) Office of Research Protections (ORP) 
Human Research Protection Office (HRPO).   
• Substantive modifications to the research protocol and any modifications that could 
potentially increase risk to subjects must be submitted to the HRPO for approval prior to 
implementation.  The USAMRMC ORP HRPO defines a substantive modification as a 
change in Principal Investigator, change or addition of an institution, elimination or 

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alteration of the consent process, change to the study population that has regulatory 
implications (e.g. adding children, adding active duty population, etc), significant change 
in study design (i.e. would prompt additional scientific review) or a change that could 
potentially increase risks to subjects.   
• Any changes of the IRB used to review and approve the research will be promptly reported 
to the USAMRMC ORP HRPO. 
• All unanticipated problems involving risk to subjects or others must be promptly reported 
by 
telephone 
(301-619-2165), 
by 
email 
(usarmy.detrick.medcom-
usamrmc.other.hrpo@mail.mil), or by facsimile (301-619-7803) to the HRPO.  A complete 
written report will follow the initial notification.  In addition to the methods above, the 
complete report can be sent to the US Army Medical Research and Materiel Command, 
ATTN:  MCMR-RP, 810 Schreider Street, Fort Detrick, Maryland  21702-5000.   
• Suspensions, clinical holds (voluntary or involuntary), or terminations of this research by 
the IRB, the institution, the Sponsor, or regulatory agencies will be promptly reported to 
the USAMRMC ORP HRPO. 
• A copy of the continuing review approval notification by the IRB of Record must be 
submitted to the HRPO as soon as possible after receipt.  Please note that the HRPO also 
conducts random audits at the time of continuing review.  Additional information and 
documentation may be requested at that time. 
• The final study report, including any acknowledgement documentation and supporting 
documents, must be submitted to the HRPO when available. 
• The knowledge of any pending compliance inspection/visit by the FDA, Department of 
Health and Human Services Office of Human Research Protections, or other government 
agency concerning this research, the issuance of Inspection Reports, FDA Form 483, 
warning letters or actions taken by any regulatory agencies including legal or medical 
actions and any instances of serious or continuing noncompliance with the regulations or 
requirements, must be promptly reported to the HRPO.  
 
9.0 SUB-STUDY: PATIENT EXPERIENCES IN THE AQUEOUS-PREP AND PREPARE 
TRIALS  
 
9.1 Introduction 
Patient and stakeholder involvement in the design of randomized controlled trials is increasingly 
becoming recognized as an essential component of a trial’s success.42,43  Patient and stakeholder 
involvement (PSI) has been seen as the paradigm shift from research being done “to” or “for” 
patients, to research being performed “with” or “by” patients themselves.44  PSI allows for 
democratization of the research process and empowering patients throughout the entire research 
process – from design through to knowledge dissemination.45  Research has found that patients 
and stakeholders are motivated to be involved in research for a wide variety of reasons, including 
a desire to contribute to research for the benefit of others.46  
 
Prior research has argued that PSI enhances the focus of clinical trials on outcomes that are relevant 
to patients themselves, thus increasing the utility of any research findings.47  Furthermore, PSI has 
been argued to improve recruitment and retention rates, while raising the quality of research 
findings and ultimately helping with the dissemination of research findings.48  Lastly, PSI may be 
able to improve patient safety when patients are involved in safety reporting in hospital settings.49  

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Despite these findings, a recent systematic review estimates that far less than 1% of clinical trials 
engage patients in any meaningful or active way.50  From the onset of the PREP-IT trials (i.e. the 
Aqueous-PREP and PREPARE trials), the PREP-IT investigators have engaged multiple patient-
partners and stakeholders in the design, conduct, and implementation of the PREP-IT trials.  One 
of our engagement goals is to identify ways in which we can better engage with PREP-IT study 
participants.  To support this goal, we seek to learn about PREP-IT participants’ experiences within 
the PREP-IT trials.  This knowledge will be used to improve the study team’s ability to engage 
study participants and provide study information in a meaningful and accessible manner.  
Additionally, the unique design of the PREP-IT trials (e.g., consent after the intervention, minimal 
follow-up, minimal requirements for participants) provides a novel trial to investigate this 
question.  This led to the current sub-study. 
 
9.2 Rationale and Objectives 
One of the mandates of the PREP-IT program is to improve orthopaedic fracture research through 
meaningful engagement with our patient-partners and stakeholders.  The objective of this sub-
study is to learn about PREP-IT participants’ experiences with participating in the Aqueous-PREP 
or PREPARE trial.  The results of this sub-study will be used to develop strategies to better engage 
research participants both in the PREP-IT trials as well as in future clinical trials.  
 
9.3 Sub-Study Design 
This sub-study will consist of an exit survey that will be given to a subset of participants in the 
PREP-IT trials.  Select clinical sites participating in the Aqueous-PREP and / or PREPARE trial 
will be invited to participate in the sub-study.  
 
The exit survey is comprised of 14 questions that includes multiple choice and brief open-ended 
questions.  All of the questions use clear and simple language written at or below a grade eight 
reading level to enhance the validity of results.  The survey length has been kept to a minimum to 
maximize response rate and limit barriers that would affect its proper completion.   
 
The survey was created after reviewing the current literature and with input from the PREP-IT 
investigators, research coordinators, patient-partners, and stakeholders.  Engaging the larger study 
team follows the PREP-IT philosophy of meaningful engagement, as well as helps to ensure that 
no vital questions were missed and that the survey wording is clear and easily understandable to 
the target audience.  The questionnaire was pre-tested on a sample of convenience.  
 
9.4 Survey Participants and Distribution 
All potential substudy participants, or their proxies, will be required to provide informed consent 
specifically for the substudy prior to completing the survey.  Informed consent for the substudy 
may be obtained at the time of enrollment in the Aqueous-PREP or PREPARE trial using consent 
procedures described in sections 4.3.1 and 7.2, or in-person at a subsequent follow-up visit or time 
of survey administration using a pen and paper consent form.  The patient or proxy must be 
provided with a copy of the signed informed consent form. All sites within the United States of 
America must conduct their consenting process in accordance with HIPAA (Health Insurance 
Portability and Accountability Act) regulations as approved by their institutions, and sites in 

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Canada must comply with the Personal Information Protection and Electronic Documents Act 
(PIPEDA). 
 
Clinical sites participating in the sub-study will offer the survey to all eligible participants at the 
time they complete their one-year follow up visit. The survey will be sent to participants either 
through mail, email or RedCap Cloud, given to them on paper at a follow-up visit, or administered 
over the phone, depending on each individual participant’s preference.  The Research Coordinator 
may also telephone or text the participant to remind them to complete the exit survey.  We will 
document the number of participants invited to participate in the survey as well as the number of 
participants who decline participation. 
 
9.5 Data Entry 
The exit survey responses will be entered into the Aqueous-PREP / PREPARE trial’s electronic 
data capture (EDC) system. 
 
9.6 Sample Size 
Sample size was calculated using a 5% margin of error, with 95% confidence intervals, a potential 
population of all patients who have completed one year follow up (approximately 1600 patients) 
and an expected response rate of 50%.  With this in mind, a sample size of approximately 310 
patients who complete every survey question will be required.51  As such, the survey will be 
distributed to all participants at participating clinical sites until our sample size of at least 310 
participants is achieved.     
 
9.7 Data Analysis 
We will summarize all variables with frequencies and percentages.  The short form questions will 
be coded appropriately based on themes.   
 
9.8 Anticipated Implications of Results 
This research serves as an important step towards understanding patients’ perspectives as 
participants in a clinical trial.  Additionally, the research may influence how future clinical trials 
are designed and conducted, with the overall goal of a greater focus on the patient experience and 
increasing patient involvement in research.  Lastly, the results of this sub-study could help the 
study team to develop aids (e.g., posters, pamphlets, etc.) to improve patients’ understanding of 
clinical research and overall experience with the PREP-IT trials.  
 

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