Linking Endotypes and Outcomes in Pediatric Acute Respiratory Distress Syndrome
Conditions: Acute Respiratory Distress Syndrome
Sponsor: Children's Hospital of Philadelphia

 
 
Title: 
Linking Endotypes and Outcomes in Pediatric Acute 
Respiratory Distress Syndrome (LEOPARDS) 
Short Title 
LEOPARDS 
Sponsor: 
NIH/NHLBI (HL148054) 
eIRB Number 
 
Protocol Date: 
March 15, 2024 
Amendment 1 Date: August 7, 2019 
Amendment 7 Date: October 7, 2022 
Amendment 2 Date: January 22, 2020 
Amendment 8 Date: December 6, 2022 
Amendment 3 Date: April 14, 2021 
Amendment 9 Date: January 27, 2023 
Amendment 4 Date: October 21, 2021 
Amendment 10 Date: May 17, 2023 
Amendment 5 Date: December 27, 2021 
Amendment 11 Date: March 15, 2024 
Amendment 6 Date: March 2, 2022 
 
Overall Study PI and CHOP Site Principal Investigator 
Dr. Nadir Yehya 
The Children’s Hospital of Philadelphia 
9NW39 Main Building 
Philadelphia, PA, 19104 
Phone 215-590-5907 
email: yehyan@chop.edu 
 

 
  
 
 
 
 
 
ii
TABLE OF CONTENTS 
Table of Contents .............................................................................................................. ii 
Abbreviations and Definitions of Terms ......................................................................... iv 
Abstract ..............................................................................................................................v 
1 
BACKGROUND INFORMATION AND RATIONALE .................................................................... 1 
1.1 
INTRODUCTION .............................................................................................................................. 1 
1.2 
RELEVANT LITERATURE AND DATA ................................................................................................ 1 
1.3 
COMPLIANCE STATEMENT .............................................................................................................. 4 
2 
STUDY OBJECTIVES ........................................................................................................................ 5 
2.1 
PRIMARY OBJECTIVE (OR AIM) ....................................................................................................... 5 
2.2 
SECONDARY OBJECTIVES (OR AIM) ................................................................................................. 5 
3 
INVESTIGATIONAL PLAN .............................................................................................................. 6 
3.1 
GENERAL SCHEMA OF STUDY DESIGN ............................................................................................. 6 
3.2 
STUDY DURATION, ENROLLMENT AND NUMBER OF SITES ................................................................ 6 
3.3 
TOTAL NUMBER OF STUDY SITES/TOTAL NUMBER OF SUBJECTS PROJECTED .................................... 7 
3.3.1 
Duration of Study Participation .......................................................................................... 7 
3.3.2 
Total Number of Study Sites/Total Number of Subjects Projected ................................. 7 
3.4 
STUDY POPULATION ....................................................................................................................... 7 
3.4.1 
Inclusion Criteria ................................................................................................................. 7 
3.4.2 
Exclusion Criteria ................................................................................................................ 7 
4 
STUDY PROCEDURES ...................................................................................................................... 9 
4.1 
SCREENING VISIT ........................................................................................................................... 9 
4.2 
STUDY PERIOD ............................................................................................................................... 9 
4.2.1 
Enrollment window ............................................................................................................. 9 
4.2.2 
Discharge ............................................................................................................................ 9 
4.3 
SUBJECT COMPLETION/WITHDRAWAL ............................................................................................ 9 
5 
STUDY EVALUATIONS AND MEASUREMENTS ........................................................................ 10 
5.1 
SCREENING AND MONITORING EVALUATIONS AND MEASUREMENTS .............................................. 10 
5.1.1 
Medical Record Review ................................................................................................... 10 
5.1.2 
Laboratory Evaluations .................................................................................................... 10 
5.2 
SAFETY EVALUATION ................................................................................................................... 11 
6 
STATISTICAL CONSIDERATIONS ............................................................................................... 12 
6.1 
PRIMARY ENDPOINT ..................................................................................................................... 12 
6.2 
SECONDARY ENDPOINTS .............................................................................................................. 12 
6.3 
CONTROL OF BIAS AND CONFOUNDING ......................................................................................... 12 
6.4 
STATISTICAL METHODS ................................................................................................................ 12 
6.4.1 
Baseline Data.................................................................................................................... 12 
6.4.2 
Analysis of Primary Outcome of Interest ........................................................................ 12 
6.5 
SAMPLE SIZE AND POWER ............................................................................................................ 14 
7 
SAFETY MANAGEMENT ............................................................................................................... 15 
7.1 
CLINICAL ADVERSE EVENTS ......................................................................................................... 15 
7.2 
ADVERSE EVENT REPORTING........................................................................................................ 15 
8 
STUDY ADMINISTRATION ........................................................................................................... 16 
8.1 
DATA COLLECTION AND MANAGEMENT........................................................................................ 16 
8.1.1 
Data sources ..................................................................................................................... 17 
8.2 
CONFIDENTIALITY ........................................................................................................................ 17 

 
 
 
 
 
 
 
iii
8.3 
REGULATORY AND ETHICAL CONSIDERATIONS ............................................................................. 17 
8.3.1 
Data and Safety Monitoring Plan..................................................................................... 17 
8.3.2 
Risk Assessment .............................................................................................................. 18 
8.3.3 
Potential Benefits of Study Participation ......................................................................... 18 
8.3.4 
Risk-Benefit Assessment ................................................................................................. 19 
8.4 
RECRUITMENT STRATEGY ............................................................................................................ 19 
8.5 
INFORMED CONSENT/ASSENT AND HIPAA AUTHORIZATION ......................................................... 19 
8.5.1 
Waiver of Consent ............................................................................................................ 20 
8.5.2 
Waiver of Assent .............................................................................................................. 20 
8.5.3 
Waiver of HIPAA Authorization........................................................................................ 20 
8.5.4 
Waiver of Consent and HIPAA Authorization ................................................................. 21 
8.6 
PAYMENT TO SUBJECTS/FAMILIES ................................................................................................ 21 
9 
PUBLICATION ................................................................................................................................. 21 
10 
REFERENCES .................................................................................................................................. 22 
 

 
  
 
 
 
 
 
iv
ABBREVIATIONS AND DEFINITIONS OF TERMS 
AE 
 
Adverse event 
ARDS 
 
Acute respiratory distress syndrome 
CART 
 
Classification and regression tree 
CHOP 
 
Children’s Hospital of Philadelphia 
CRF 
 
Case report form 
ELISA 
 
Enzyme Linked Immunosorbent Assay 
HIPAA 
 
Health Insurance Portability and Accountability Act 
IRB 
 
Institutional review board 
LCA 
 
Latent class analysis 
PICU 
 
Pediatric intensive care unit 
PELOD 
 
Pediatric logistic organ dysfunction score 
PRISM-III 
 
Pediatric risk of mortality-III 
VPS 
 
Virtual PICU System 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
  
 
 
 
 
 
v
ABSTRACT 
Context:  Acute respiratory distress syndrome (ARDS) is a heterogeneous 
syndrome of acute respiratory failure which affects 45,000 children in the United 
States annually.  Heterogeneity has contributed to negative trials, as interventions 
useful in one sub-type may not be useful in another.  Biomarkers have the potential 
to identify sub-phenotypes of pediatric ARDS which may benefit from targeted 
therapy. 
Objectives: Our overall goal is to risk stratify pediatric ARDS patients and to identify 
sub-phenotypes with shared biology in order to appropriately target therapies in 
future trials.  Specifically, we aim to: 
Aim 1:  Validate and refine PARDSEVERE, a published protein biomarker-based 
pediatric ARDS risk stratification tool 
Aim 2:  Stratify pediatric ARDS into sub-phenotypes using a known 100-gene 
expression-based classifier to group subjects according to shared underlying 
biology  
Aim 3:  Identify de novo sub-phenotypes in pediatric ARDS using biomarkers and 
whole genome transcriptomics of peripheral blood 
Study Design:  
This is a prospective, multicenter study upwards of 500 intubated children with 
ARDS, with planned blood collection within 24 hours of ARDS onset and 
subsequent measurement of plasma protein biomarkers and peripheral blood gene 
expression. 
Setting/Participants: 
We will enroll upwards of 500 intubated children with ARDS from 16 academic 
pediatric intensive care units in the United States.   
Study Interventions and Measures:  
We will measure pre-determined biomarkers with known or suspected association 
with ARDS severity or outcome.  Simultaneously, we will measure gene expression 
of peripheral blood.  Both plasma biomarkers and gene expression profiles will be 
analyzed using various machine learning techniques, including classification and 
regression tree, latent class analysis, and hierarchical clustering with the goal of 
identifying sub-phenotypes of ARDS.  These sub-phenotypes will be examined for 
association with outcome (primary is 28-day mortality), and explicitly tested for 
variation in response to exogenous treatments (e.g., corticosteroids).

 
  
 
  
 
 
 
1 
1 
BACKGROUND INFORMATION AND RATIONALE       
1.1 Introduction 
Acute respiratory distress syndrome (ARDS) is common and deadly in 
children:  ARDS is characterized by acute onset of diffuse bilateral pulmonary 
edema and severe hypoxemia not fully explained by cardiac dysfunction [1, 2].  
Primarily defined for adults, ARDS affects 45,000 children in the United States 
annually [3], representing 10% of mechanically ventilated children in pediatric 
intensive care units (PICUs)[4], with a mortality rate of 20% in the United States and 
30% worldwide [5-7].  There are no specific pharmacological therapies for adult [8-
19] or pediatric [20-23] ARDS despite several trials, and supportive care with lung-
protective ventilation [24] and fluid restriction [25] remains the mainstay of 
treatment.  ARDS is a heterogeneous syndrome, with patients having distinct co-
morbidities and inciting etiologies (pneumonia, non-pulmonary sepsis).  This 
heterogeneity has contributed to negative trial results, as therapies effective in 
some patients are ineffective in others [26].  Methods to reduce heterogeneity, 
including sub-phenotyping using protein and mRNA biomarkers, have been 
proposed for improving patient selection for future clinical trials [27].   
Studies are needed specifically in pediatric ARDS:  In children, a lack of 
therapies is further compounded by uncertainty in management, as guidelines are 
typically extrapolated from adult ARDS, with uncertain applicability [28].  However, 
pediatric ARDS possesses a distinct epidemiology [29], outcomes [30], and 
pathobiology [31], necessitating studies specific to this population.  We have 
published how the lower mortality rate in children necessitates alternative patient-
centered outcomes for observational and interventional studies [32].  Additionally, 
as risk factors and co-morbidities differ from adult ARDS [29, 33, 34], studies 
specifically investigating the pathophysiologic changes leading to increased alveolar 
permeability in children are sorely needed, and are currently lacking.  For example, 
pediatric ARDS spans birth to 18 years of age, encompassing different stages of 
lung development.  Over 13% of children with ARDS have a history of prematurity 
[35] and are at high risk for impaired pulmonary vascular and parenchymal growth, 
which contributes to hypoxemia, cardiac dysfunction, organ failure, and outcomes in 
pediatric ARDS in a manner distinct from adult ARDS [36].   
1.2 Relevant Literature and Data 
Adult ARDS possesses distinct subtypes representing different 
pathophysiologic mechanisms:  In adult ARDS, studies of biomarkers collected 
during clinical trials [37-39] have led to the discovery of endotypes, or sub-
phenotypes with shared pathophysiologic, biomarker, or transcriptomic profiles [27].  
Two distinct endotypes, dubbed “hypo-” and “hyperinflammatory” have consistently 
been discovered in 4 trials using latent class analysis (LCA), a form of cluster 
analysis.  The hyper-inflammatory endotype was characterized by higher 
proportions of patients in shock, with sepsis, and higher levels of inflammatory 
biomarkers.  Three biomarkers (interleukin-8 [IL-8], bicarbonate, and soluble tumor 
necrosis factor-1 [sTNFR1]) adequately discriminated the two endotypes.  These 

 
  
 
  
 
 
 
2 
endotypes have clinical relevance, as they showed differential association with 
higher positive end-expiratory pressure (PEEP) [37], conservative fluid 
management [38], and to simvastatin [39], with benefits of these interventions only 
seen in the hyperinflammatory endotype.  Additional work in adult ARDS has 
demonstrated different biomarker profiles between direct (primarily pulmonary) and 
indirect (primarily non-pulmonary) inciting etiologies, with elevated lung epithelial 
damage biomarkers seen in direct ARDS, and elevated endothelial biomarkers in 
indirect [40], suggesting that these may also represent endotypes.  However, to 
date, there has not been demonstration of differential response to therapies based 
on stratification by direct or indirect ARDS biomarker profiles.       
Pediatric ARDS possesses distinct subtypes representing different 
pathophysiological mechanisms:  Investigations of whether clinically relevant 
endotypes exist in pediatric ARDS are in their infancy.  Our group has demonstrated 
that infectious and non-infectious ARDS, defined using clinical variables, have 
different predictors of mortality [34], suggesting the possibility of distinct endotypes.  
Very recently, endotypes defined by differential circulating levels of matrix 
metalloproteinases (MMP) were reported in a separate, smaller cohort of pediatric 
ARDS, with higher mortality in the “hyperinflammatory” endotype [41].  However, 
this is the sole example of biomarker-based endotyping in pediatric ARDS, and 
requires replication in a larger, prospective cohort.  Furthermore, these endotypes 
were defined solely using MMP pathway proteins, and it is unclear whether 
endotypes defined using a broader array of biomarkers would prove more 
informative. 
Identification of endotypes allows for predictive enrichment in clinical trials:  
Identifying endotypes with common underlying biology is requisite for predictive 
enrichment – selection of subjects more likely to respond to trial interventions based 
on a biological mechanism [26, 27].  In adult ARDS, the association between 
mortality and higher PEEP, conservative fluid management, or simvastatin was only 
observed in the hyperinflammatory endotype [37-39], suggesting that future trials of 
these interventions, which had no mortality benefit in the parent trials enrolling 
heterogeneous ARDS, should be restricted to this responsive endotype.  Pediatric 
ARDS, with its lower mortality rate and distinct etiologic and co-morbidity profile, 
requires its own endotyping strategy, and cannot a priori rely on adult evidence.  In 
pediatric sepsis, Dr. Hector Wong (a co-Investigator on this proposal) has designed 
a gene expression-based endotyping strategy which identified two distinct 
endotypes with differential expression of glucocorticoid receptor signaling genes 
and with divergent response to corticosteroids [42-44].  Whether pediatric ARDS 
possesses clinically relevant endotypes with differential response to therapies 
remains unknown, and is the key goal of Aims 2 and 3.      
Protein biomarkers can stratify mortality risk and allow for prognostic 
enrichment in pediatric ARDS:  In addition to predictive enrichment, biomarkers 
have also been proposed for prognostic enrichment – the selection of subjects more 
likely to have the outcome of interest to improve power to detect an effect of an 
intervention [26, 27].  We developed and published a biomarker-based risk 
prediction tool (PARDSEVERE) which stratifies pediatric ARDS into low-, medium-, 

 
  
 
  
 
 
 
3 
and high-risk for mortality in 152 subjects from a single center [45].  PARDSEVERE 
used age and three plasma biomarkers (IL-8, macrophage inflammatory protein 1-α 
[MIP1α/CCL3], and heat shock 70kDa protein 1B [HSPA1B]), and discriminated 
non-survivors with an area under the receiver operating characteristic curve 
(AUROC) of 0.85, outperforming other severity of illness scores.  The low-risk strata 
had mortality < 5%, while the high-risk strata had mortality > 30%.  If validated in 
Aim 1, this strategy could be used to identify subjects who should be either 
excluded (low-risk subjects with low probability of improved mortality from 
intervention) or included (subjects with higher predicted mortality) in an 
interventional trial.  Furthermore, risk stratification and predictive enrichment can be 
combined to further identify endotypes which may have differential responses to 
therapies (Figure 1).   
 
 
 
 
 
Biomarker-based endotyping and risk stratification offers advantages over 
clinical variables:  Clinical variables offer little detail about underlying 
pathophysiology.  This is relevant when considering targeted therapies beyond 
supportive care.  For example, we have shown that angiopoietin-2 (ANG2) and 
soluble receptor for advanced glycation end-products (sRAGE), markers of 
endothelial and lung epithelial dysfunction, respectively, are elevated in pediatric 
ARDS non-survivors [46], suggesting utility for prognostic enrichment as well as 
mechanistic implications.  Therapies targeting the ANG2 [47] and RAGE pathways 
[48] are already in pre-clinical trials.  Biomarker characterization of pediatric ARDS 
would allow restriction of trial subjects to those with evidence of dysregulated ANG2 
or RAGE pathways, combining prognostic and predictive enrichment. 
Our group has demonstrated advantages of biomarker-based prognostic and 
predictive enrichment over clinical variables alone.  Recently, we showed how a 
positive response to inhaled nitric oxide (iNO), defined by an improvement in 
oxygenation of ≥ 20%, was associated with shorter ventilator duration in pediatric 
ARDS [49].  No clinical variables, including age, history of prematurity, vasopressor 
support, echocardiographic evidence of pulmonary hypertension, etiology of ARDS, 
or baseline oxygenation predicted oxygenation response to iNO.  However, levels of 
ANG2, a biomarker of endothelial dysfunction, predicted a positive oxygenation 
response.  Separately, we developed PARDSEVERE using classification and 
regression tree (CART) methodology [45].  We tested several clinical variables, 
including known predictors of mortality (oxygenation, organ failure, 
immunocompromised status, vasopressor support) for inclusion in the model.  
However, CART selected age plus three biomarkers (IL-8, MIP1α, HSPA1B) as the 
final model.  A possible explanation for this finding is that the mortality risk from 
Figure 1:  Hypothetical example 
of combining biomarker-based 
risk stratification (using 
PARDSEVERE) with 
transcriptomic-based 
endotyping.  This theoretical 
construct was used to identify 
children with sepsis who were 
more likely to benefit from 
corticosteroids (35). 

 
  
 
  
 
 
 
4 
being immunocompromised were better explained using biomarkers, rather than a 
clinical designation of immune status.  In both cases, we demonstrated how 
biomarker-based enrichment and risk stratification can add value above clinical 
variables alone.       
1.3 Compliance Statement 
This study will be conducted in full accordance all applicable Children’s Hospital of 
Philadelphia Research Policies and Procedures and all applicable Federal and state 
laws and regulations including 45 CFR 46.  All episodes of noncompliance will be 
documented. 
The investigators will perform the study in accordance with this protocol, will obtain 
consent and assent, and will report unanticipated problems involving risks to 
subjects or others in accordance with The Children’s Hospital of Philadelphia IRB 
Policies and Procedures and all federal requirements. Collection, recording, and 
reporting of data will be accurate and will ensure the privacy, health, and welfare of 
research subjects during and after the study. 
 
 

 
  
 
  
 
 
 
5 
2 
STUDY OBJECTIVES 
The proposed studies will establish the presence and clinical relevance of protein 
and mRNA biomarker-defined endotypes in pediatric ARDS.  Additionally, the 
studies will validate a mortality risk stratification tool which can be developed to 
provide real-time prognostic enrichment in future trials.  Successful completion of 
the Aims will significantly advance our understanding of pediatric ARDS, provide 
insight into underlying pathophysiology, and provide testable hypotheses on 
whether the association between specific treatments used in pediatric ARDS and 
outcomes differ by endotypes.  
2.1 Primary Objective (or Aim) 
This protocol has 3 specific Aims: 
Aim 1:  Validate and refine PARDSEVERE, a published protein biomarker-based 
pediatric ARDS risk stratification tool 
Aim 2:  Stratify pediatric ARDS into endotypes using a known 100-gene expression-
based classifier to group subjects according to shared underlying biology  
Aim 3:  Identify de novo endotypes in pediatric ARDS using biomarkers and whole 
genome transcriptomics of peripheral blood  
2.2 Secondary Objectives (or Aim) 
The secondary objectives are to: 
• Associate endotypes with 28-day mortality 
• Associate endotypes with duration of mechanical ventilation 
• Associate differential response of therapies (e.g., corticosteroids) dependent 
upon endotypes. 
 
 

 
  
 
  
 
 
 
6 
3 
INVESTIGATIONAL PLAN 
3.1 General Schema of Study Design 
The proposal is a prospective observational cohort study of pediatric ARDS taking 
place at 16 centers in the Unites States.  The study involves simultaneous collection 
of plasma (for measurement of circulating biomarkers) and RNA-stabilized whole 
blood (for microarrays) within 24 hours of ARDS onset in upwards of 500 children 
(Figure 2). 
 
 
 
 
 
 
3.2 Study Duration, Enrollment and Number of Sites 
The study will be funded for 5 years (anticipated start date of July 1, 2019 until June 
30, 2024).  We anticipate enrollment beginning January 1, 2020 and lasting until 
December 31, 2022 (3 years).  We have budgeted ample time for start-up (6 
months) and extension of enrollment (up to 2 years) in case of slower than expected 
enrollment.  Sixteen US sites have expressed interest: 
• Children’s Hospital of Philadelphia (DCC and main site) 
• Cincinnati Children’s Hospital Medical Center (Cincinnati, OH) 
• Nationwide Children’s Hospital (Columbus, OH) 
• Texas Children’s Hospital (Houston, TX) 
• Children’s Hospital of Wisconsin (Milwaukee, WI) 
• Akron Children’s Hospital (Akron, OH) 
• Nicklaus Children’s Hospital (Miami, FL) 
• Children’s Mercy Hospital (Kansas City, MO) 
• Penn State Hershey Children’s Hospital (Hershey, PA) 
• Cooperman Barnabas Medical Center (Livingston, NJ) 
• Riley Children’s at Indiana University Health (Indianapolis, IN) 
• Columbia University Medical Center (New York, NY) 
• Arkansas Children’s Hospital (Little Rock, AR) 
• Children’s Healthcare of Atlanta (Atlanta, GA) 
Figure 2:  Integration and design of the 
proposed studies. 

 
  
 
  
 
 
 
7 
• Children’s Hospital Colorado (Aurora, CO) 
• Washington University (St. Louis, MO) 
 
3.3 Total Number of Study Sites/Total Number of Subjects Projected 
3.3.1 Duration of Study Participation 
The study duration per subject will be up to PICU discharge.  Subject involvement 
will be limited to the single approach for consent, and a single blood draw, both 
within 24 hours of eligibility (i.e., ARDS onset).  The subject will be followed until 
PICU discharge for collection of clinical data (mortality status, duration of ventilation, 
therapies used). 
3.3.2 Total Number of Study Sites/Total Number of Subjects Projected 
The study will be conducted at 16 investigative sites in the United States. 
Recruitment will stop when 500 subjects are enrolled with samples collected.  It is 
expected that up to 550 subjects will be recruited to produce 500 evaluable subjects 
for the plasma biomarker aims, and approximately 475 evaluable subjects for the 
mRNA aims to account for subjects with only partial samples collected. 
3.4 Study Population 
3.4.1 Inclusion Criteria  
1) acute (≤ 7 days of risk factor) respiratory failure requiring invasive mechanical 
ventilation 
2) age > 44 weeks corrected gestational age and < 17.5 years 
3) invasive mechanical ventilation via endotracheal tube 
4) bilateral infiltrates on chest radiograph 
5) oxygenation index (OI) ≥ 4; or oxygen saturation index (OSI) ≥ 5 on 2 
consecutive measurements at least 4 hours apart but < 24 hours apart 
6) invasively ventilated ≤ 7 days before meeting above radiographic and 
oxygenation criteria 
3.4.2 Exclusion Criteria 
1) weight < 3 kilograms 
2) cyanotic congenital heart disease (other than Patent Foramen Ovale (PFO) or 
Patent Ductus Arteriosus (PDA)) 
3) tracheostomy at time of screening 

 
  
 
  
 
 
 
8 
4) invasively ventilated for > 7 days when meet ARDS criteria above 
5) cardiac failure as predominant cause of respiratory failure 
6) primary obstructive airway disease (asthma, bronchiolitis) by judgement of 
clinician as the primary cause of respiratory failure 
7) alternative known chronic lung disease as cause of respiratory failure (cystic 
fibrosis, eosinophilic pneumonia, interstitial pneumonitis, pulmonary 
hemosiderosis, cryptogenic organizing pneumonia) 
8) severe neurologic morbidity not expected to survive > 72 hours 
9) any limitations of care at time of screening 
10) previous enrollment in this study 
 
Subjects that do not meet all of the enrollment criteria may not be enrolled. Any 
violations of these criteria must be reported in accordance with IRB Policies and 
Procedures.  We limited enrollment to subjects < 17.5 years to preclude any 
subjects from turning 18 during their PICU stay (median length of ventilation for 
ARDS in 9 days). 

 
  
 
  
 
 
 
9 
4 
STUDY PROCEDURES 
4.1 Screening Visit 
Subjects will be screened daily at the respective PICUs by trained research 
coordinators.  Intubated subjects will be assessed for study eligibility by chart 
review, and if necessary, discussion with the treating team.  No subjects or 
parents/guardians will be approached for consent until deemed eligible.  Potential 
subjects will not be asked screening questions prior to obtaining informed consent. 
All individuals meeting all inclusion criteria and none of the exclusion criteria will be 
approached for study enrollment within 24 hours of meeting eligibility criteria.  After 
confirming eligibility, patients will be approached for informed consent  
4.2 Study Period  
4.2.1 Enrollment window 
Study procedures will be performed at enrollment for all subjects.  Subjects will be 
eligible ≤ 24 hours after eligibility, defined as the time-point of the second qualifying 
OI or OSI (see Inclusion criteria).  Study procedures are: 
• Start of paper CRF and uploading into web-based Redcap database 
• Blood collection for plasma and mRNA analysis 
4.2.2 Discharge 
Subjects will be followed for duration of PICU stay until PICU discharge, death, or 
90 days after enrollment.  Data for the stay will be collected in the paper CRF and 
uploaded on-site to a web-based Redcap database. 
4.3 Subject Completion/Withdrawal 
Subjects may withdraw from the study at any time without prejudice to their care.  It 
will be documented whether or not each subject completes the clinical study.  
 

 
  
 
  
 
 
 
10
5 
STUDY EVALUATIONS AND MEASUREMENTS 
5.1 Screening and Monitoring Evaluations and Measurements 
5.1.1 Medical Record Review 
All clinical data will be generated at the discretion of the care team and attending 
physician.  The following data will be abstracted from the medical chart (paper or 
electronic): 
Category 
Data to be Collected 
Demographic 
Date of birth, date of PICU admission/transfer, date of 
discharge, gender, race/ethnicity, weight, height 
Medical history 
Comorbid illnesses, lung injury diagnosis, organ failure 
score 
Blood gas data 
PaO2, PaCO2, pH 
Ventilator data 
Mode of ventilation, peak inflating pressure, mean 
airway pressure, positive end-expiratory pressure, 
compliance, dead space fraction 
Laboratory data 
White blood cell count, chemistries, lactate 
Outcomes 
Ventilator days, PICU survival 
Vital Status 
Alive or deceased at PICU discharge 
 
5.1.2 Laboratory Evaluations 
Example: Blood sampling will be performed for the following laboratory evaluations 
• 
Plasma biomarker measurements 
• 
Genome-wide mRNA expression from whole blood 
5.1.2.1 Blood Sampling 
A total of 6.1 mL whole blood will be taken from each patient within 24 hours of 
meeting study eligibility. 
5.1.2.2 Blood Processing 
Whole blood will be collected in 3 tubes.  Two sodium citrate (“light blue top”) tubes 
will receive 1.8 mL each (total = 3.6 mL).  These two tubes will be centrifuged within 
30 minutes (2000 g for 20 minutes at 20°C).  Plasma samples (supernatant) will be 
divided into aliquots and stored at -20°C at sites other than CHOP, and then sent to 
CHOP every 2 weeks on dry ice, where they will be stored long-term at -80°C.   
An additional 2.5 mL will be stored in a PAXgene tube for RNA, stored upright at 
room temperature for 4 to 24 hours, and then stored at -20°C at sites other than 
CHOP, and then sent to CHOP every 2 weeks on dry ice, where they will be stored 

 
  
 
  
 
 
 
11
long-term at -30°C.  Analyses will be conducted on both plasma and mRNA at 
CHOP, using enzyme-linked immunosorbent assays (ELISAs) or the Molecular 
Biology Core for microarray, as appropriate. 
5.2 Safety Evaluation 
Patient safety will be monitored by noting any adverse events that occur during or 
as a consequence of study blood collection.  Study blood collection should pose no 
increased risk for complications greater than that of standard clinical blood 
collection, and total blood volume collected does not exceed age/weight-appropriate 
maximums (which is why < 3 kg weight is an exclusion criteria).   

 
  
 
  
 
 
 
12
6 
STATISTICAL CONSIDERATIONS 
6.1 Primary Endpoint 
The primary endpoint of Aim 1 is successful performance of the PARDSEVERE risk 
stratification tool to discriminate 28-day mortality in pediatric ARDS.  The primary 
endpoint of Aim 2 is application of a known 100-gene classifier to test whether 
transcriptomic endotypes exist in pediatric ARDS.  The endpoint of Aim 3 is 
generation of novel proteomic and transcriptomic endotypes. 
6.2 Secondary Endpoints 
Secondary endpoints will include association of endotypes with mortality and 
ventilator-free days at 28 days.   
6.3 Control of Bias and Confounding 
While not completely possible to control for bias in an observational study, we have 
taken certain steps to minimize the risk of confounding.  The primary exposure is 
biomarker (protein or mRNA)-defined endotypes.  Clinical data will be collected on 
paper CRFs on-site and uploaded to a central, web-based Redcap server.  
Biomarker measurements will be made in bulk post-clinical data collection.  Thus, 
clinical data is being collected blinded to the biomarker levels or endotype 
assignments.  Finally, the statisticians involved in this data analysis will be blinded 
to outcomes (mortality); endotype assignments will be performed on presenting 
clinical variables and biomarker measurements.   
6.4 Statistical Methods 
6.4.1 Baseline Data  
Baseline and demographic characteristics will be summarized by standard 
descriptive summaries (e.g., means and standard deviations or medians with 
interquartile ranges for continuous variables and proportions for categorical 
variables).  Comparisons between survivors and non-survivors, and later between 
different endotypes, will be tested using unpaired t-test or Wilcoxon rank sum test 
for continuous variables.  The analogues of these tests for > 2 groups (ANOVA and 
Kruskal-Wallis) will be used if > 2 endotypes are identified.  Fisher’s exact or chi-
squared test will be used for categorical variables. 
6.4.2 Analysis of Primary Outcome of Interest 
For Aim 1, PARDSEVERE biomarker levels will be used to classify subjects 
according to the previously published PARDSEVERE decision rules without 
modifications [45].  This allows for assignment of 28-day mortality risk based on 
allocation of study subjects to one of 5 terminal nodes.  Performance of 
PARDSEVERE will be assessed by AUROC for discriminating 28-day mortality and 
other diagnostic accuracy measures, including sensitivity, specificity, and positive 
and negative predictive values at different probability cutoffs.  PARDSEVERE will 

 
  
 
  
 
 
 
13
be considered validated if sensitivity is ≥ 0.85 and specificity is ≥ 0.65, both with 
95% CI width ≤ 0.16.   
For Aim 2, we will perform mRNA gene expression, and identify endotypes using a 
previously published 100-gene classifier [42, 43].   
For Aim 3, we will identify de novo endotypes using LCA including biomarker and 
clinical variables, or novel endotypes using the entire gene expression pattern.   
For the transcriptomic part of Aims 2 and 3, the cohort will be split 60:40 into a 
derivation and test set.  In Aim 2, we will determine genome-wide differential gene 
expression.  After filtering and normalizing, gene expression values will be ranked 
by median absolute deviation across all patient samples.  We will then perform 
unsupervised agglomerative hierarchical clustering on the top 5000 probesets, with 
clusters allowed k = 2-12, as has been done to discover mRNA-based endotypes in 
adult sepsis [50].  To estimate k (number of endotypes), we will combine cumulative 
distribution functions and cophenetic distance correlation analysis to assess 
clustering stability.  Using a random forest classifier (supervised classification with 
high dimensional data methods)[50, 51], we will assess ARDS endotype 
classification with ten-fold cross-validation of stepwise increments in gene numbers.  
We will decide on the final number of endotype-defining genes when the process 
yields a cross-validation misclassification error rate of < 10%. 
For the protein biomarker part of Aim 3, the cohort will be split 60:40 into a 
derivation and test set.  We will use all measured plasma biomarkers and select 
clinical variables recorded within 24 hours of ARDS onset, including age, 
vasopressor-inotrope score [52], specific laboratory values including PELOD 2, 
bicarbonate, and OI at ARDS onset.  These variables were chosen based on their 
ability to discriminate mortality in previous studies of adult [37] or pediatric ARDS 
[35], including by our group [34], and their ready availability within the first 24 hours 
of ARDS.  All analyses will be performed blinded to outcome.  As scales of variables 
vary considerably, continuous variables will be standardized to mean = 0 and 
standard deviation = 1 prior to analysis.  We will consider models between 2 and 5 
subclasses, as has been done for adult ARDS [37-39].  For LCA, criteria for model 
selection will be based on the Bayesian Information Criteria, the Vuong-Lo-Mendell-
Rubin likelihood ratio test, and size of the smallest class. Model estimation will be 
based on full-information maximum likelihood methods.  To avoid local maximum 
likelihood solutions, we will use 100 random starting values, of which the best 20 
will be optimized.    
For secondary aims, assuming a mortality rate of 16%, a 50:50 split between 
endotypes, and α = 0.05, with 475 subjects we have 80% power to detect an 
association with an odds ratio ≥ 2.0 between endotype and 28-day mortality.  
Importantly, as the goal of endotype discovery is not mortality prediction [53], we 
are not powering for this outcome.  Rather, we provide this calculation here for 
reference of what effect size endotype has on mortality that we will be able to 
observe. 

 
  
 
  
 
 
 
14
6.5 Sample Size and Power 
For Aim 1, assuming a mortality rate of 16% and a PARDSEVERE sensitivity of 
0.85 and specificity of 0.65, the sample size needed for two-sided 95% CI width of ≤ 
0.16 (i.e., sensitivity of 0.85 with 95% CI 0.77 to 0.93) is 454 subjects.  In our single-
center study of 152 subjects and 16% mortality [45], our sensitivity was 0.96 and 
specificity was 0.66, suggesting that these assumptions are realistic.  We have 
increased this to 500 total subjects with samples collected to account for ~10% of 
subjects being unevaluable due to sample loss or degradation during transport and 
storage. 
For the transcriptomic Aims 2 and 3, we anticipate 475 evaluable subjects with 
sufficient RNA from the total cohort of 500 subjects with samples collected, 
assuming a conservative estimate of 5% drop-out due to neutropenia.  As we found 
evidence for ARDS endotypes in our preliminary cohort of 67 subjects, we 
anticipate adequate numbers for endotype discovery.  As a comparison, in adult 
sepsis, 4 endotypes were discovered using whole blood gene expression from 306 
subjects [50]. 
 
 

 
  
 
  
 
 
 
15
7 
SAFETY MANAGEMENT 
7.1 Clinical Adverse Events 
Clinical adverse events (AEs) will be monitored throughout the study.  
7.2 Adverse Event Reporting 
Since the study procedures are not greater than minimal risk, SAEs are not 
expected. If any unanticipated problems related to the research involving risks to 
subjects or others happen during the course of this study (including SAEs) these will 
be reported to the IRB in accordance with CHOP IRB SOP 408: Unanticipated 
Problems Involving Risks to Subjects. AEs that are not serious but that are notable 
and could involve risks to subjects will be summarized in narrative or other format 
and submitted to the IRB at the time of continuing review.  

 
  
 
  
 
 
 
16
8 
STUDY ADMINISTRATION 
8.1 Data Collection and Management 
For patients who meet eligibility criteria, the parents or legal guardians will be 
approached for study enrollment.  The site PIs or trained staff members will engage 
them in a discussion regarding reasons for the study, the study procedures, and the 
risks and benefits and answer all questions.  Due to the critical nature of the 
patients’ conditions in the PICU, this discussion may take place at the patient’s 
bedside or in an alternative location (e.g., family conference room) at the 
parent/guardian’s option and the study investigator’s discretion.  All reasonable 
safeguards to ensure patient privacy will be taken.  Parents/guardians will be given 
sufficient time (i.e., up to several hours) to decide whether or not to participate in 
this study.  Following the above conversation seeking informed consent from each 
patient’s parent/guardian and obtaining agreement from the parent/guardian to 
participate in this study, we will provide a copy of the combined consent-HIPAA 
authorization document to the parent/guardian and patient.   
We also have a waiver of assent for all patients.  Given the inclusion criteria of 
invasive mechanical ventilation, and the necessary associated sedation, we do not 
anticipate any instances of subjects being able to assent. 
Paper versions of all CRFs will be kept on-site in a locked office.  Data will be 
entered into web-based online CRF (Redcap) that will be password-protected.  Only 
study personnel authorized by the IRB will have access to study-related data and 
files, and have password access to the online CRF.     
Confidentiality will be assured by keeping the list containing personal health 
identifiers (PHI) and subject ID restricted to the individual sites, such that the only 
data submitted to CHOP is limited in PHI (site, dates of ARDS, demographic 
information) and coded with a subject ID number.  Furthermore, all downloaded 
study-related data will be kept in encrypted, password-protected files on the PI’s 
desktop computer in a locked office, with password-protected back-ups on the 
Departmental share drives for research.  Dr. Yehya (PI) and study personnel 
authorized by the IRB will have access to this data.   
Specific consent will be obtained to store blood and use data for future research, 
which will be explicitly recorded.  There will be plans to share this data with the 
research community using the Biologic Specimen and Data Repository Information 
Coordinating Center (BioLINCC) program at NHLBI, and we will follow suggested 
guidelines for de-identifying the data (coding of site IDs, conversion of dates to 
study days). 
Pursuant to the NIH position that sharing of resources (such as this study) is an 
important means to enhance the value of NIH-sponsored research, all data obtained 
from this proposal will be made readily available for research by qualified individuals 
within the scientific community after publication of the proposed studies.  Gene 
expression data from Aims 2 and 3 will be made available simultaneous with 
publication of the results of these aims by uploading to the Gene Expression 

 
  
 
  
 
 
 
17
Omnibus, consistent with the NIH Genomic Data Sharing Policy.  For dissemination 
of plasma biomarker results and the associated clinical dataset, we will use the 
Biologic Specimen and Data Repository Information Coordinating Center 
(BioLINCC) program at NHLBI, with release of a de-identified dataset with 
appropriate untraceable identifiers within 2 years of publication of the main 
manuscript, alongside a detailed mechanism of how to request data samples.  As 
we intend to use a layered consent, with an option to opt out of future studies, we 
will ensure this information is conveyed to BioLINCC.  
8.1.1 Data sources  
Data will be collected by trained research staff from the patient’s inpatient chart.  In 
the majority of cases, we anticipate this being an electronic medical record, rather 
than a paper chart. 
8.2 Confidentiality 
All data and records generated during this study will be kept confidential in 
accordance with Institutional policies and HIPAA on subject privacy.  The 
Investigator and other personnel will not use such data and records for any purpose 
other than conducting the study. 
Confidentiality will be assured by keeping the list containing personal health 
identifiers (PHI) and subject ID restricted to the individual sites, such that the only 
data submitted to CHOP is limited in PHI (site, dates of ARDS, demographic 
information) and coded with a subject ID number.  Furthermore, all downloaded 
study-related data will be kept in encrypted, password-protected files on the PI’s 
desktop computer in a locked office, with password-protected back-ups on the 
Departmental share drives for research.  Dr. Yehya (PI) and study personnel 
authorized by the IRB will have access to this data. 
No identifiable data will be used for future study without first obtaining IRB approval. 
The investigator will obtain a data use agreement between provider (the PI) and any 
recipient researchers (including others at CHOP) before sharing a limited dataset 
(demographics, dates).  
8.3 Regulatory and Ethical Considerations 
8.3.1 Data and Safety Monitoring Plan 
All data and records generated during this study will be kept confidential in 
accordance with Institutional policies and HIPAA on subject privacy and that the 
Investigator and other site personnel will not use such data and records for any 
purpose other than conducting the study.  Confidentiality will be assured by keeping 
the list containing personal health identifiers (PHI) and subject ID restricted to the 
individual sites, such that the only data submitted to CHOP is limited in PHI (site, 
dates of ARDS, demographic information) and coded with a subject ID number.  
Furthermore, all downloaded study-related data will be kept in encrypted, password-
protected files on the PI’s desktop computer in a locked office, with password-

 
  
 
  
 
 
 
18
protected back-ups on the Departmental share drives for research.  All study-related 
files will be secured on password-protected drives.    
All blood specimens will be collected and stored using tubes labeled with a study ID 
number.  Any remaining blood specimens following study measurements will be 
stored in a coded manner after obtaining specific informed consent to store these 
specimens and use for future research purposes.  No identifiable data or PHI will be 
used for future study without first obtaining IRB approval. 
8.3.2 Risk Assessment 
The risks for patients participating in this study are not greater than minimal risk and 
include those related to 1) blood collection for study measurements and 2) breach 
of confidentiality.  There is no other practical way to collect data for the proposed 
research.  
Risks related to blood collection:  The volume of blood collection will be limited to 
6.1 mL per one-time draw in all subjects. In any patient whose clinical condition 
might be adversely affected by removal of the stated blood volume for this study 
(e.g., patients with significant anemia or compromised cardiac output), we will 
discuss further limiting the volume of blood withdrawn for research purposes with 
the patient’s attending physician. Any patient concurrently enrolled in another study 
for whom enrollment in this study would mean the combined blood volume 
collection would exceed IRB regulations will be excluded from this study and the 
reason for exclusion noted. Finally, since patients with ARDS typically undergo 
multiple blood draws per day, whenever possible blood sampling for study purposes 
will be timed with other clinically indicated lab draws in order to limit access to 
indwelling vascular catheters.  
Risks related to breach of confidentiality: Extensive efforts will be taken to protect 
this information including storage of downloaded data in an encrypted, password-
protected desktop, and keeping the majority of the PHI at the respective sites, with 
only a limited dataset utilizing unique study IDs used for the majority of data 
analyses.  PHI will be removed as soon as is practical after data collection.  If 
families choose not to participate, data will not be collected for study purposes.  The 
CHOP IRB requires annual updates for continuing approval for all studies, and the 
CHOP Office of Research Compliance and Regulatory Affairs performs routine 
audits of all protocols.  
8.3.3 Potential Benefits of Study Participation 
Pediatric ARDS carries substantial morbidity and mortality, with no directed 
therapies available.  Guidelines for management are often extrapolated from adult 
ARDS, despite the distinct epidemiology and outcomes in pediatric ARDS.  Studies 
specifically investigating the mechanisms underlying pediatric ARDS are needed.  
The proposed studies will lay the foundation for improved risk stratification of 
pediatric ARDS, and potentially for the identification of specific sub-populations 
which may benefit from trials of targeted therapies.  While there are no direct 
benefits to patients as a result of participation in this study, these indirect benefits 
for future pediatric patients with ARDS may lead to improved outcomes.   

 
  
 
  
 
 
 
19
8.3.4 Risk-Benefit Assessment 
Given the minimal risk profile associated with this study, the overall benefits to 
science, pediatric medicine, future generations of children with ARDS, and society 
as a whole clearly outweigh the risks.   
8.4 Recruitment Strategy 
Potential study patients will be recruited from the PICU population.  All intubated, 
mechanically ventilated patients will be eligible for screening.    Reviewing inclusion 
and exclusion criteria and confirming eligibility as part of recruitment will involve 
querying the medical records and discussion with the patient’s care team only.  
Potential subjects will not be asked screening questions prior to obtaining informed 
consent.  Since all inclusion and exclusion eligibility criteria will be determined 
based on clinical documentation in the medical record and no further information 
about the prospective participant will be required to determine if they are eligible for 
the research, consent for the recruitment and screening process is not required. 
For patients who meet eligibility criteria, the parents or legal guardians will be 
approached for study enrollment.  The site PIs or trained staff members will engage 
them in a discussion regarding reasons for the study, the study procedures, and the 
risks and benefits and answer all questions.  Due to the critical nature of the 
patients’ conditions in the PICU, this discussion may take place at the patient’s 
bedside or in an alternative location (e.g., family conference room) at the 
parent/guardian’s option and the study investigator’s discretion.  All reasonable 
safeguards to ensure patient privacy will be taken.  Parents/guardians will be given 
sufficient time (i.e., up to several hours) to decide whether or not to participate in 
this study.  Following the above conversation seeking informed consent from each 
patient’s parent/guardian and obtaining agreement from the parent/guardian to 
participate in this study, we will provide a copy of the combined consent-HIPAA 
authorization document to the parent/guardian and patient.   
8.5 Informed Consent/Assent and HIPAA Authorization 
For patients who meet criteria, the parents or legal guardians will be approached for 
study enrollment.  The site PI, co-investigators, or trained staff members will engage 
them in a discussion regarding reasons for the study, the study procedures, and the 
risks and benefits and answer all questions.  Due to the often critical nature of the 
patients’ conditions in the PICU, this discussion may take place at the patient’s 
bedside or in an alternative location (e.g., family conference room) at the 
parent/guardian’s option and the study investigator’s discretion.  Also, since it is 
common for parents/guardians to be away from the bedside, we anticipate the need 
to seek consent over the phone for many patients.  Regardless of the where this 
discussion takes place (i.e., in person or via telephone), all reasonable safeguards 
to ensure patient privacy will be taken.  Parents/guardians will be given sufficient 
time (i.e., up to several hours) to make a decision to participate in this study. 
Following the above conversation seeking informed consent from each patient’s 
parent/guardian and obtaining agreement from the parent/guardian to participate in 

 
  
 
  
 
 
 
20
this study, we will provide a copy of the combined consent-HIPAA authorization 
document to the parent/guardian and patient.   
We will also seek a waiver of assent for all patients, in accordance with 
regulations 45 CFR 46.408(a)..  Given the inclusion criteria of invasive 
mechanical ventilation, and the necessary associated sedation, we do not 
anticipate any instances of subjects being able to assent.    
8.5.1 Waiver of Consent 
A waiver of documentation of consent and HIPAA authorization is approved in 
cases when informed verbal consent is obtained due to subject families being 
unable to provide written consent due to religious observances or due to consent 
being obtained over the phone, under 45CFR46.117(c)(2). This study presents no 
more than minimal risk of harm to subjects and does not involve any procedures for 
which written consent is normally required outside of the research context. In 
accordance with 45CFR46.117(c)(2), we will document verbal consent and verbal 
HIPAA Authorization on the consent form and a note written in the subject’s medical 
record. 
If the parent/guardian consents to participate in the study, further verbal consent will 
be sought to store any remaining blood specimens following completion of study 
measurements for possible use in future research.  Consent to store blood for future 
use will be indicated on the same consent form (layered consent) by the person 
obtaining informed consent.   
For non-English speaking patients, at sites where the short form consent process is 
approved for written and verbal consent, the short form will be read to the potential 
subjects before the summary document is translated; the interpreter will sign the 
short form and summary document to document that this has been done.  The 
person obtaining consent shall sign the summary document, and the consenting 
party will sign the short form (the latter only if written consent/HIPAA authorization 
are obtained). Each site that uses the short form consent process to enroll LEP 
subjects will abide by local policies and procedures pertaining to the process (both 
in person and/or via phone, as applicable). 
8.5.2 Waiver of Assent 
A waiver of assent is approved for all patients, in accordance with regulations 45 
CFR 46.408(a). Given the inclusion criteria of invasive mechanical ventilation, 
and the necessary associated sedation, we do not anticipate any instances of 
subjects being able to assent.   
8.5.3 Waiver of HIPAA Authorization 
A waiver of documentation of consent (see above) and a waiver of 
documentation of HIPAA authorization is approved in cases when informed 
verbal consent is obtained due to subject families being unable to provide written 
consent due to religious observances or due to consent being obtained over the 
phone, under 45CFR46.117(c)(2). This study presents no more than minimal risk 
of harm to subjects and does not involve any procedures for which written 

 
  
 
  
 
 
 
21
consent is normally required outside of the research context.  In accordance with 
45CFR46.117(c)(2), we will document verbal consent and verbal HIPAA 
Authorization on the consent form and a note written in the subject’s medical 
record. 
8.5.4 Consent Plan for Columbia University Medical Center  
Columbia University Medical Center has been granted a waiver of documentation of 
consent and a waiver of documentation of HIPAA authorization in order to obtain 
consent verbally as described above in section 8.5.1 for those whose parents are 
not at the bedside.  
Columbia is attempting to limit all unnecessary interactions between the patient 
and/or family and non-clinical staff, to include research personnel to mitigate the 
increased risk of potentially spreading highly contagious viruses such as COVID-19. 
Columbia has been granted approval to obtain written consent using alternative 
methods as outlined below:  
• The site investigator and trained research staff will email the consent to 
families, the study can be discussed via phone and the conversation 
documented in the subject file, and then the family will sign and email the 
consent form back to the study team. 
• The study team will drop off a paper consent form at the bedside, the study 
can be discussed via phone and the study team will document the 
conversation in the subject file, and the family can sign the paper form which 
can then be picked up at a later date (i.e. when the study team goes to 
complete the study procedures). 
8.6 Payment to Subjects/Families 
No monetary or physical reimbursement will be provided to patients or their families 
for participation in this study.  The cost of all study measurements will be covered 
by the investigational team. 
9 
PUBLICATION 
This study will be carried out with the goal of publication of results in a peer-
reviewed journal.  Only de-identified aggregate data will be published. 
 
 

 
  
 
  
 
 
 
22
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