A Decision Support System for Self-management of Low Back Pain - a Randomized Controlled Trial for the selfBACK Project
Phase: NA
Conditions: Low Back Pain
Sponsor: University of Southern Denmark

 
 
Project no: 689043 
Acronym: SELFBACK 
Title: A decision support system for self-management of low back pain 
Activity: PHC-28-2015 Predictive modelling RIA 
 
Work Package 5:  
Protocol for the SELFBACK Randomised 
controlled trial 
Author(s): 
Louise Fleng Sandal1, Mette Jensen 
Stochkendahl1, Malene Jagd Svendsen4, Karen 
Wood2, Cecilie Øverås3, Anne Lovise 
Nordstoga3, Charlotte Nørregaard Rasmussen4, 
Barbara Nicholl2, Kay Cooper5, Kerstin Bach3, Per 
Kjær1, Tom Ivar Lund Nilsen3, Jan Hartvigsen1, 
Frances Mair2, Paul Jarle Mork3, Karen Søgaard1 
Partners: 
1: UoSD  
2: GLA 
3: NTNU  
4: NFA  
Keywords: 
Protocol, RCT, digital decision support system, 
app, low back pain, outcomes and effect 
measures. 
 
 
 
 

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Table of Contents 
1. 
Introduction .............................................................................................................................................. 4 
1.1. 
Objectives ......................................................................................................................................... 4 
2. 
Methods .................................................................................................................................................... 5 
2.1. 
Trial design ........................................................................................................................................ 5 
2.2. 
Study setting ..................................................................................................................................... 5 
2.3. 
Selection criteria ............................................................................................................................... 5 
2.4. 
Identification and recruitment of participants by health care professionals (HCP) ..................... 6 
2.5. 
Screening for eligibility and enrolment by researchers .................................................................. 6 
2.6. 
Randomisation ................................................................................................................................... 8 
2.7. 
Blinding ............................................................................................................................................. 9 
3. 
Interventions ............................................................................................................................................ 9 
3.1. 
Usual care .......................................................................................................................................... 9 
3.2. 
SELFBACK in addition to usual care .................................................................................................. 9 
3.2.1. 
The digital DSS ........................................................................................................................ 10 
3.2.1. 
Wearable device and supporting apps .................................................................................. 11 
3.2.2. 
The SELFBACK self-management plans .................................................................................. 11 
3.2.3. 
SELFBACK mobile app .............................................................................................................. 13 
3.2.4. 
Access, frequency and mode of delivery .............................................................................. 14 
3.3. 
Ancillary and post-trial management ............................................................................................ 14 
4. 
Outcomes ................................................................................................................................................ 14 
4.1. 
Primary outcome ............................................................................................................................ 14 
4.2. 
Secondary outcomes ...................................................................................................................... 14 
5. 
Statistics .................................................................................................................................................. 16 
5.1. 
Sample size estimations ................................................................................................................. 16 
5.2. 
Statistical analysis ........................................................................................................................... 17 
6. 
Data collection ........................................................................................................................................ 17 
6.1. 
Data collection ................................................................................................................................ 17 
6.2. 
Access to data ................................................................................................................................. 18 
7. 
Pilot testing ............................................................................................................................................. 18 
8. 
Process evaluation .................................................................................................................................. 19 
9. 
Trial management ................................................................................................................................... 19 
9.1. 
Research ethics approval ............................................................................................................... 19 
9.2. 
Protocol amendments .................................................................................................................... 19 
9.3. 
Trial monitoring ............................................................................................................................... 19 
9.3.1. 
Harms ...................................................................................................................................... 19 
9.3.2. 
Auditing ................................................................................................................................... 20 
9.4. 
Declaration of interests .................................................................................................................. 20 
9.5. 
Dissemination policy ....................................................................................................................... 20 
 
 
 

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Protocol for the SELFBACK trial: 
 
Effectiveness of a tailored app-delivered self-management program for reducing pain-related 
disability in people with low back pain - a protocol for the SELFBACK randomised controlled trial. 
 
This protocol follows the recommendation for items from the Standard Protocol items: 
Recommendation for Intervention Trials (SPIRIT, 2013) [1] and Consolidated Standards Of Reporting 
Trials (CONSORT, 2010) guidelines [2]. Additionally the E-health extension to the CONSORT checklist has 
been used as a guideline for describing the digital intervention [3]. 
 
Protocol version:  
1.2 (date of last update 2019.02.20).  
 
Trial registration:  
Trial registry will be completed at www.clinicaltrials.gov. The randomised controlled trial (RCT) is 
registered under id no: NCT03798288. Registration was completed before recruitment of participants to 
the RCT was initiated.  
 
Roles and responsibilities: 
The partners involved in the SELFBACK project include:  
1. The Norwegian University of Science and Technology (NTNU), Trondheim, Norway 
2. The University of Glasgow (GLA), Glasgow, Scotland 
3. The Robert Gordon University (RGU), Aberdeen, Scotland 
4. Trade eXpansion (TRX), Tommerup, Denmark 
5. National Research Centre for the Working Environment (NFA), Copenhagen, Denmark 
6. Health Leads BV (HLE), Amsterdam, Netherlands 
7. University of Southern Denmark (UoSD), Odense, Denmark  
 
NTNU is leading the development of the underlying structure for the database and decision support 
system (DSS), RGU has been leading the physical activity monitoring and TRX has been leading the 
mobile app development. The medical partners (NTNU, GLA, RGU, NFA and UoSD) have developed 
content for the app. The RCT is a multi-centre trial, patients are recruited at NTNU and UoSD; UoSD is 
lead in the planning and conducting of the RCT; UoSD is lead in the process evaluation. NTNU is leading 
the overall project.  
 
Funding  
The SELFBACK project has received funding from the European Union Horizon 2020 research and 
innovation programme under grant agreement no 689043. The funding body supervises the conduct of 
the overall project, but is not involved in the planning, implementation and interpretation of data from 
the RCT. 
 
 

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1. Introduction 
Low back pain (LBP) is worldwide a major contributor to years lived with pain and disability. In the 
Global Burden of Disease studies of 2010 and 2015, it was estimated that LBP is the leading cause of 
years lived with disability in most countries [4, 5]. In the vast majority of people experiencing LBP 
specific pathoanatomical causes cannot be identified and more than 85% of people seen in primary care 
are categorised as having "non-specific” LBP [6]. The economic costs of health-care, sickness absence, 
lost ability to work, social benefits and treatment costs of non-specific LBP are high and can be 
considered a societal burden [7-9]. 
Clinical guidelines recommend patient education, exercise therapy, multidisciplinary treatments and 
combined physical and psychological interventions to manage LBP [10-14]. Although national clinical 
guidelines may differ in scope and context, the recommendations are rather consistent across countries 
[10-12, 15-17]. Self-management programmes that include elements of such recommended treatment 
components have been suggested as a promising option for chronic conditions including non-specific 
LBP [18]. Self-management may be defined as the individual’s ability to care for own health by managing 
symptoms, physical and psychological consequences and impact on life [18]. In LBP, the effectiveness of 
self-management has been reported to be moderate for pain and small to moderate for disability [19, 
20].  The lack of effect is likely to be explained by lack of tailoring of the programme to the individual 
and support to persist with self-management [21], and such factors may also have a negative effect on  
adherence to self-management programmes. Lastly, as self-management is broadly defined, the 
content of self-management programmes varies between the reported trials [19].   
Digital solutions, such as mobile applications (apps), have been suggested as platforms for 
supporting self-management of chronic conditions [22, 23]. Within recent years, a vast number of apps 
has been introduced to the commercial market for self-management of LBP. A 2016 systematic review 
identified 61 apps and concluded that available apps have poor quality, included poor quality 
information from questionable sources and that none of the apps had been tested for effectiveness 
[24]. While a recent systematic review by the SELFBACK team highlighted that the literature is 
heterogeneous, and the evidence base remains weak [25], the SELFBACK project aims to fill this 
knowledge gap by developing an evidence-based and data-driven decision support system (DSS) 
delivered via a smartphone app to facilitate, improve and reinforce self-management of non-specific 
LBP [26]. The DSS suggests self-management plans consisting of physical activity advice, patient 
education and recommendations for physical exercise tailored to the individual’s specific health 
information. The effectiveness of the DSS will be evaluated in a RCT. Additionally, a process evaluation 
will be carried out in parallel to the RCT (section 8) [27], as this will be important to aid understanding of 
uptake and utilisation as well as future implementability. 
 
1.1. Objectives  
The objective is to evaluate the effectiveness of the SELFBACK DSS in addition to usual care versus usual 
care only in a RCT. Primary outcome is pain-related disability at three months (primary endpoint). We 
hypothesise that participants randomised to using the SELFBACK app in addition to usual care will have at 
least two points difference in pain-related disability at three months, measured by the Roland-Morris 
Disability Questionnaire (RMDQ), compared to participants receiving usual care only. 
The effectiveness of the intervention on secondary outcomes, including quality of life, use of 
non-prescriptive medication, sleep problems, depressive symptoms, stress, functional ability and pain 

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intensity, will be assessed at three months. We will also evaluate the effect on these outcomes at six 
and nine months.  
 
2. Methods 
2.1. Trial design 
The SELFBACK study is designed as an international multi-centre superiority RCT with two parallel groups, 
testing the relative effectiveness of the SELFBACK DSS in addition to usual care (intervention group) 
versus usual care only (control group) for participants with non-specific LBP. 
 
2.2. Study setting 
The recruitment of participants will be conducted in two countries: Trondheim, Norway (NO) and 
Odense, Denmark (DK). In both NO and DK, participants will be recruited from general practice, 
physiotherapy and chiropractic clinics. Additionally, in DK recruitment will also be from the Spine Centre 
in the Region of Southern Denmark. The Spine Centre is an outpatient hospital that reviews patients 
with back pain referred from primary care. The Spine Centre provides diagnostic assessment of patients 
and prescribes treatment plans according to national treatment guidelines. Patients seen at the Spine 
Centre without serious pathologies will be referred to the SELFBACK study.  
 
2.3. Selection criteria  
Participants must meet all the following eligibility criteria:  
• 
Seeking care from primary health-care practice or a specialised outpatient hospital facility (DK) for 
non-specific LBP within the past 8 weeks 
• 
LBP of any duration 
• 
Mild-to severe pain-related disability rated as 6 or above on the Roland Morris Disability 
Questionnaire (RMDQ)  
• 
Age ≥18 years 
• 
Own and regularly use a smart phone (with at least Android 6.0+ or iOS11.0+) with internet access 
(Wi-Fi and/or mobile data) 
• 
Have a working email address and have access to a computer with internet access to complete 
questionnaires in a web browser. 
 
Presence of any of the following criteria will exclude participants from enrolling in the RCT:  
• 
Not interested 
• 
Unable to speak, read or write in the national language (Danish/ Norwegian) 
• 
Cognitive impairment or learning disabilities  
• 
Mental or physical disease or health problem limiting participation in the study (Examples are 
fractures or pathologies, such as cancer, inflammatory diseases, and signs of radiculopathy (severe 
leg pain, loss of leg strength, or loss of or altered sensation in a myotomal or dermatomal 
distribution)) 
• 
Unable to take part in exercise/physical activity (such as non-ambulatory patients, use of walking 
aids/assistance, unable to get down and up from the floor independently) 
• 
Fibromyalgia (diagnosed by a health care professional (HCP))  

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• 
Pregnancy 
• 
Previous back surgery 
• 
Ongoing participation in other research trials for LBP management. 
 
The assessment of whether the criteria are considered to limit participation is performed either by the 
referring HCP during the recruitment phase (see green box in Figure 1) or by participant self-report 
during the screening call (see blue box in Figure 1). 
 
2.4. Identification and recruitment of participants by health care professionals (HCP) 
The recruitment period is planned to start in March 2019. A total of 350 participants are to be recruited 
to the RCT. Of these, 75% (n=262) will be recruited in DK and 25% in NO (n=88). In each country, 
collaborations with local clinics and HCPs will be established to facilitate recruitment. The number of 
clinics and HCPs needed to ensure sufficient recruitment rate has been informed by the pilot study 
(August 2018–January 2019).  
The recruitment process is outlined in the green box in Figure 1. Patients seeking care due to non-
specific LBP will be invited to participate in the trial. The HCP will refer potentially eligible participants 
based on a short description of eligibility. Final eligibility will be assessed by the research team during a 
screening phone call (blue box in Figure 1). The referral to the SELFBACK trial will take place after the HCP 
has performed routine diagnostic assessment or treatment (usual care). Participants are recruited 
through two pathways, registry data or live recruitment. 
Recruitment from registries will be conducted at the Spine Centre in DK. Participants are sent an 
invitation letter including written information about the project. The written information describes 
three ways to contact the research team, if the participant is interested in the project: 1) by email, 2) 
telephone (call or text message), or 3) a link where contact information can be entered. For the registry 
recruitment in DK, a list of patients will be extracted every week from the Spine Centre’s registry, who 
consulted in the past week with LBP according to the inclusion criteria.  
For the live recruitment of participants, the HCP identifies patients seen in their clinical practice who 
are eligible for self-management of LBP. The HCP briefly informs the patient about the project and 
provides the patient with written information. This information is the same as given in the registry 
recruitment. If interested, patients can contact the research team by 1) email, 2) telephone (call or text 
message), or 3) add their contact information to a sign-up sheet at the clinic.  
 
2.5. Screening for eligibility and enrolment by researchers 
The screening process is outlined in the blue box in Figure 1. Participants who have indicated that they 
are interested in the project are contacted via telephone by a researcher in the SELFBACK team. During 
this call, oral information about the trial is given to the participant and questions about the project and 
project participation can be answered. A detailed eligibility screening is performed via a pre-defined 
screening form including the inclusion and exclusion criteria described above.  
The enrolment process is outlined in the grey box in Figure 1. If eligible and willing to participate, 
the participants give their verbal consent to participate and are sent an email with a link to the web-
based baseline questionnaire. After a participant has completed the baseline questionnaire the 
informed consent will be signed, and the randomisation performed via a web-based randomisation 
system (see section 2.6). A small difference in this procedure is evident between countries due to 

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difference in requirements from the local Ethics Committees. In NO, the written consent form is 
included in the written information provided by the HCP. The participant can return the signed informed 
consent in a pre-stamped envelope as provided by the HCP or alternatively, the participant can take a 
picture of the signed consent form and send it via a text message to the researchers. Hereafter, the 
researcher will call the participant and inform about the result of the randomisation and give 
instructions according to group allocation. If randomised to the control group, all instructions are 
completed on the phone. If randomised to the intervention group, the participant is required to attend 
a face-to-face meeting to have the app installed on their phone and be given the wristband to wear. In 
DK, all participants are invited to a face-to-face meeting, where the consent form is signed and 
hereafter the randomisation is performed. All instructions are given verbally at this meeting.  
If randomised to a) the selfBACK DSS in addition to usual care, participants are given wearable 
device along with instructions and assistance on how to download, install and pair the wearable device 
with the app and how to connect the apps on the smartphone (see section 3.2.1). Moreover, the 
participant is given information about their follow-up assessments and information on how to contact 
the researcher if needed. If a participant declines participation at the face-to-face meeting, the 
researcher will ensure that the information from the baseline questionnaire is deleted.  
If randomised to b) usual care, participants are instructed on the principles of usual care, and 
are given the same information as the SELFBACK intervention group about the follow-up assessments 
and how to get in touch with the researcher if needed. 
 
The flow of participants through the trial is described in Figure 1. 

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Figure 1: Participant flow through SELFBACK trial. Abbreviations: GP: general practitioner, PT: physiotherapist, C: 
chiropractor, HCP: Health care provider, LBP: Low Back Pain 
 
2.6. Randomisation 
Participants are randomised to either a) SELFBACK DSS in addition to usual care or b) usual care only. The 
randomisation is performed as a block randomisation with permuted blocks of random size unknown to 
the research team and stratified by country and care provider (i.e. general practitioner, physiotherapist, 

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chiropractor, or Spine Centre). The allocation ratio between the SELFBACK DSS in addition to usual care 
and the usual care groups is 1:1. Randomisation will be performed by a web-based randomisation system 
(Web Case Report Form; WebCRF) developed and administered by Unit of Applied Clinical Research, 
Faculty of Medicine and Health Sciences, NTNU, Trondheim, Norway. This unit is not otherwise involved 
in the trial management or trial conduct. A contractual agreement has been signed with the Unit of 
Applied Clinical Research concerning their role and responsibilities in the project. The WebCRF system 
will hold a minimal data set on all screened participants (variables include: a trial id number, country, 
care provider, recruitment site, age, gender). 
 
2.7. Blinding 
The study is a single-blinded study. Participants are not blinded to group allocation. The analysis and 
interpretation of the study results will be performed by researchers blinded to group allocation. Once 
the study is completed, a copy of the data will be extracted in pseudonymised form for statistical 
analyses. All personal information that may lead back to specific participants (i.e. e-mail address, 
username etc.) will be removed from the data. The information concerning group allocation will be 
added to the dataset with the intervention and control group randomly labelled as A and B. The 
randomisation key (i.e. document entailing information on which group is which) is kept at the Unit of 
Applied Clinical Research at NTNU. They will provide the randomisation key to the research team once a 
blinded interpretation of the results is finalized (see section 5.2).  
 
3. Interventions 
3.1. Usual care 
Participants randomised to usual care will follow any diagnostic or treatment-related pathway (e.g. 
receive information, advice or treatment) as instructed by their HCP. They are also allowed to seek care, 
treatment or help elsewhere as normal. After the completion of the trial at 9 months, participants who 
have completed all follow-up assessments are contacted and offered a wearable device similar to the 
SELFBACK intervention group.  
 
3.2. SELFBACK in addition to usual care 
The SELFBACK intervention is a digital DSS for self-management of LBP provided to the participant via a 
smartphone app (SELFBACK app) [26]. In addition, the participant is provided with a wearable device (i.e., 
a step-detecting wristband) that interacts with the SELFBACK app. Based on the step count and 
participant’s self-reported data, the SELFBACK app provides individually tailored self-management plans 
including educational messages, physical activity advice and exercise recommendations matched to the 
participant’s health status, as generated by the DSS. Importantly, the intervention is not intended to 
replace follow-up by HCPs, but to supplement the ordinary care by the HCP, and the participant is 
informed accordingly. Thus, participants randomised to the SELFBACK intervention may continue to seek 
care, treatment or help as normal. 
Stakeholder and user involvement are increasingly seen as essential especially in the context of 
complex interventions. It is seen as important to enhance engagement, empowerment and to maximize 
long-term sustainability. User involvement has been a key feature during the development of the selfBACK 
system and the design of trial procedures. We have had direct input from patients through a range of 
mechanisms that are described elsewhere [26]. The content of the intervention was developed using 

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Intervention Mapping (IM). IM is a six-step process with each step consisting of several tasks, which, once 
completed, inform the next step, as detailed by Bartholomew et al. [28]. The IM process aims to facilitate 
participation and consultation from all relevant stakeholders. It provides a structure for the integration 
of theory, empirical findings from the literature, and information collected from the target population. 
In short, the first step of the IM process of this project consisted of a review of international clinical 
practice guidelines for management of LBP. The guidelines consistently endorse important elements 
such as education about LBP, and uptake of evidence-based self-management behaviours by 
participants; including physical activity and specific exercises as well as cognitive behavioural therapy 
(CBT) to promote self-management for people with LBP [10, 12, 15-17]. Additionally, literature on self-
management of LBP and studies on physical activity, exercise or education (including CBT) was 
reviewed for inspiration for specific content for each component. Finally, patient leaflets and other 
patient information delivered through websites or apps were reviewed for content of self-management 
for LBP. The intervention mapping process for the SELFBACK intervention will be described in detail in a 
separate publication. 
 
3.2.1.  The digital DSS 
The SELFBACK system constitutes a data-driven predictive DSS that uses the Case-Based Reasoning 
(CBR) methodology [29] to capture and reuse participant cases in order to suggest the most suitable 
self-management plan for participants. The data sources for the CBR system comprise 1) the initial 
participant data collected by the baseline web-based questionnaire, 2) a weekly report by the 
participant in the SELFBACK app (including pain, function, fear-avoidance, workability, sleep, self-
efficacy, stress, health belief and barriers), and 3) the step-detecting wearable. On a weekly basis, this 
information is used to revise the self-management plan by matching the characteristics of the current 
participant case with existing successful participant cases in the SELFBACK case-base. The weekly 
tailoring questions will only be given if relevant for the participant. As an example, if a participant has 
indicated sleep problems at baseline, then a tailoring question will be asked in appropriate time-
intervals, and, based on the answer, a set of educational messages on e.g. sleep hygiene will be offered 
to the participant. Consequently, the DSS will deliver an individualised self-management plan for the 
coming week via the SELFBACK app. All interaction between the participant and the SELFBACK DSS 
happens via the SELFBACK app. There is no interaction between the DSS and HCPs. The architecture of 
the DSS and the interaction between the participant, the wearable device, the SELFBACK app and the 
database is outlined in Figure 2. A full description of the DSS is published elsewhere [30].  
 

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Figure 2: Overview of the SELFBACK decision support system. 
 
3.2.1. Wearable device and supporting apps 
The Xiaomi Mi Band 3 wristband is used to track number of steps. The step count is synchronized with 
the GoogleFit app on Android devices and Apple HealthKit app on iOS devices throughout the day. The 
wristband registers movement in all three planes (frontal, horizontal and sagittal) via an ADI (Analog 
Devices, Inc.) ultra-low power acceleration sensor and computes step-count from this information. It 
connects to the phone via Bluetooth (V4.2 BLE) and requires Android 4.4+ / iOS 9.0+.1 The wearable 
device is to be worn on the participant’s wrist continuously while participating in the intervention but 
could be taken of during sleep and water-based activities. To connect the wristband and step count 
function to the SELFBACK app, the MiFit app is required to be installed on the participant’s smartphone. 
Additionally, Apple HealthKit needs to be activated on iOS devices, and GoogleFit needs to be activated 
or downloaded if not preinstalled on Android devices. The three apps (i.e., MiFit, Apple HealthKit and 
GoogleFit) are freely available, and can be downloaded without cost for the participant. An account 
needs to be created for the apps for every participant. An installation guide has been developed to help 
participants install and connect apps, and a researcher will be present at the time of installation to 
ensure the correct setup.  
 
3.2.2. The SELFBACK self-management plans 
The DSS builds the self-management plan from three types of content: 1) physical activity level (i.e., step 
count) and goals, 2) a bank of physical exercises, and 3) a bank of educational material. An overview of 
the available content is presented in Figure 3.  
 
                                                          
1More details:  
https://www.mi.com/in/mi-band-3/specs/ 

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Physical activity 
Physical activity is tracked as described for the wearable device (see section 3.2.1). The SELFBACK app 
prompts the participant to set a goal for physical activity by suggesting a gradual increase in daily steps 
if the past week’s goal was achieved. A 10% increase is suggested, until a goal of 10.000 steps per day is 
reached. The participant can adjust the suggested goal, before accepting it. During the week, the 
participant can see the achieved step-count per day and track his/her progress. The lowest step count 
goal that is possible to set is 3000 steps per day. This limit is based on average step count numbers from 
previous studies in workplace pedometer intervention (average ~6000 steps) [31] and home-based 
pedometer intervention in older adults with knee problems (average ~3500 steps) [32]. The minimum 
step count goal of 3000 per day was chosen to reflect that participants in the trial have functional 
disability that may also affect their physical activity level. Based on the achieved daily step count from 
the previous week, the step count goal for the coming week is adjusted, and educational messages and 
notifications aimed to motivate more physical activity is pushed through the SELFBACK app.  
 
Exercise programme 
The physical exercise material is compiled of 70 exercises organised in 6 targets (back-, abdominal-, 
gluteal-, and core muscle strength, pain relief and flexibility). Each participant is given an individualised 
exercise programme, the default recommendation is to perform exercises in 3-5 sessions per week of 20 
minutes (e.g. four exercises with an estimated duration of five min per exercise). The number of 
exercises is adjusted according to the participant’s indication of time available for doing exercise and to 
the anticipated level of difficulty defined by baseline questionnaire. An exercise programme will always 
include either 1) a strength exercise for abdominal and back extensor muscles, or 2) one strength 
exercise for the core muscles. Additionally, exercises targeting strength in hip and gluteal muscles, 
flexibility of the spine, or pain-relieving exercises may be included in the programme. If a participant 
presents with an acute pain flare-up or high pain ratings, the app will offer pain-relieving exercises only 
until an acceptable pain level is achieved. 
An exercise is presented to the participant in the app with a short video accompanied by a 
written instruction that includes recommendations on number of sets and repetitions. The participant 
will be prompted in the app to report completed number of sets and repetitions per exercise. The DSS 
will offer a new exercise at a more difficult or easier level in the coming week, based on the level of 
completion registered. In addition, participants can request new exercises (at the same level of 
difficulty and within the same group of exercises) if they experience problems completing the 
suggested exercise. The included exercises were extracted from studies identified in international 
guidelines for treatment of LBP [10, 33], and systematic reviews on effect of exercises in LBP treatment 
[34-39]. The organisation, targets and progression of exercises were guided by consensus discussions 
among experienced clinicians and researchers within the SELFBACK project team.  
 
Education 
The educational material is structured under 14 main categories (“information about LBP”, 
“understanding mind-body”, “self-management for LBP”, “thoughts, behaviour, attitude and feeling”, 
“fitting in self-management in a busy life”, “first aid when your back hurts”, “LBP and comorbidities”, 
“goal-setting and action planning”, “pacing and graded activity”, “problem solving”, “relaxation”, 
“sleep and LBP”, “social support” and “overcoming barriers for self-management of LBP”). For each 

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main category, a tree-structure of educational messages has been created. Every short message is 
about 140 characters long. Some messages may include links to longer, more explanatory text (max 500 
characters) or tools that can be used to help with self-managing LBP, e.g. goal setting tool, sleep advice, 
etc. Some short messages are also rewritten into “quizzes”, where the educational content is rephrased 
into a yes or no type question. When answering a quiz, a response is displayed to the participant stating 
the correct answer with additional explanation. A total of 230 short messages or quizzes are available in 
the educational material. 
 
 
Figure 3: Overview of available content within the SELFBACK app 
 
3.2.3. SELFBACK mobile app 
The individually tailored self-management plan is delivered via the SELFBACK app. The SELFBACK app is 
developed by TRX in close collaboration with the other SELFBACK partners. The development of the first 
version of the app has been completed (by December 2017). The SELFBACK app was tested in a pilot 
study starting August 2018 (section 7). Feedback from the pilot participants was implemented into the 
app; however, the core content and features did not change. The app and DSS will be frozen and tested 
in the RCT. To increase transparency and facilitate replicability of the intervention, the version of the 
app and DSS used in the RCT will be preserved. A short video representation of the app will be made 
publicly available after the RCT has been completed. 
 
 

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3.2.4. Access, frequency and mode of delivery 
The participants access their self-management plan via the SELFBACK app and enter data into the DSS by 
answering tailoring questions in the app and by wearing the connected wearable device. These data are 
combined with the participant self-reported outcome as outlined in Figure 2. The participant is 
encouraged to use the SELFBACK app daily or at least once a week, in order to be offered a new self-
management plan. The app will send push-notifications reminding the participant to open the app and 
view the new self-management plan. The participant can disable or adjust the frequency of notifications 
in the app settings. The goal of the intervention is that participants learn to self-manage their LBP, 
which may potentially result in participants discontinuing their use of the app. Consequently, 
discontinuation is not necessarily a sign of low compliance but may indicate a high self-management 
level.  
 
3.3. Ancillary and post-trial management 
All participants randomised to the SELFBACK intervention can continue their use of the wearable device 
after the trial. However, their access to the SELFBACK app will cease after the 9 months follow-up, by 
disabling the participants username, thereby restricting login to the app. All participants randomised to 
the usual care group are offered a wearable device after completing all follow-up assessments. No 
further post-trial management is planned.  
 
4. Outcomes 
All outcomes are collected at baseline, six weeks, three, six and nine months. Additionally, participant 
characteristics and demographic variables are collected at baseline. Participant characteristics include 
age, gender, height, weight, and relevant comorbidities. The demographic variables include family 
relations, ethnicity, educational status, employment, and work characteristics if employed. The 
outcomes included in the trial were based on recommendations for LBP trials [40-42].  
 
4.1. Primary outcome 
The RMDQ assesses pain-related disability [43]. The questionnaire includes 24 items asking participants 
to indicate if they experience functional impairments by answering “yes” or “no” to a series of 
descriptions of functional abilities [44]. The RMDQ score ranges from 0 to 24, where a higher score 
indicates higher levels of disability due to LBP [44, 45]. The RMDQ is a validated and recommended tool 
for measuring pain-related disability in LBP populations [41, 45, 46]. The minimal clinically important 
difference for the RMDQ has been reported to be five points in LBP populations with baseline scores 
ranging between 14-16 points [47]. The SELFBACK trial aims to detect a two-point difference after three 
months. This is less than the suggested five-point reduction stated as minimally clinically important. 
Also, if the two-point difference does not exceed the measurement error of the RMDQ, the results will 
then be difficult to apply on an individual level in clinical practice. The measurement error of the RMDQ 
has been reported to range between 1.4-3.7 in studies comparing the RMDQ to the Oswestry Disability 
Index, with three studies reporting measurement error to range between 1.4 to 1.8 and one study 
reporting 3.7 [48]. Given that the SELFBACK intervention is an add-on to usual care and supposed to be a 
supplement to existing treatment rather than a substitution, a smaller difference can be justified.  
 
4.2. Secondary outcomes 

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The average and worst LBP intensity within the past week will be assessed by asking “Please indicate 
your average/worst low back pain level during the last week“, using an 11-point numerical rating scale 
(NRS) ranging from zero to 10. The NRS is a valid and commonly used outcome for measuring pain in 
adults [40, 49, 50]. Pain duration measures length of participants’ current back pain episode and total 
duration of time with LBP by asking “What is the length of time you have had low back pain during this 
episode?” with scoring ranging from less than 1 week to more than 12 weeks and “What is the total 
length of time that you have had low back trouble during the last 12 months?” with scoring ranging 
from 0 days to everyday. Measures of pain intensity and duration are recommended as a core set of 
outcomes for LBP trials [40]. Pain medication evaluates the frequency of non-prescription pain 
medication use for LBP by asking “How many days during the last week have you taken non-
prescription pain medication for low back pain?”  
 
The Fear-Avoidance Belief Questionnaire (FABQ) assesses participant’s beliefs about how physical 
activity and work affect their LBP [51]. The FABQ is a 5-item questionnaire, where the participants score 
their beliefs about their LBP on an ordinal scale ranging from zero [completely disagree] to six 
[completely agree]. The Pain Self-Efficacy Questionnaire (PSEQ) assesses the participant’s level of 
confidence in carrying out specific activities despite their pain [52, 53]. The PSEQ is a 10-item 
questionnaire scored on an ordinal scale ranging from zero [completely disagree] to six [completely 
agree]. 
Activity Limitation evaluates if LBP has limited work and leisure time activities. The 
questionnaire consists of two single items with response options “yes” and “no.” Work Ability is 
measured by a single-item and rated on an 11-point NRS scale ranging from zero [completely unable to 
work] to 10 [work ability at its best] [54]. 
 
Self-reported physical activity is evaluated by a revised version of the Saltin-Grimby Physical 
Activity Level Scale, where participants indicate their amount of time per week performing leisure 
activities with four levels of intensity ranging from sedentary to vigorous physically active [55]. Function 
is evaluated by the Patient Specific Functional Scale (PSFS) where the participants, on up to two self-
selected activities, are asked to rate if they are unable to do or are having difficulty with their ability to 
perform self-selected activities regarded as important by the participants themselves [56, 57]. The 
ability to carry out the activity/activities is rated from zero [unable to perform] to 10 [able to perform].  
 
Sleep is assessed by self-report using four items concerning problems with falling asleep, waking 
up repeatedly, waking up too early, and feeling sleepy during the day [58]. Items are scored in three 
categories; [seldom or never], [sometimes] or [several times a week]. The information retrieved from 
these four items approximates the information necessary to diagnose insomnia according to the DSM-V 
criteria [59]. Stress is evaluated with the Perceived Stress Scale (PSS), a 10-item questionnaire asking 
about frequency of thoughts and feelings related to perceived stress [60]. Participants indicate their 
frequency of experiencing stress-related issues on a 5-point Likert scale, ranging from [never] to [very 
often]. 
 
Three outcome measures are included to assess general health and perception of illness. Health-
related quality of life is evaluated with the EuroQoL 5-dimension (EQ-5D) questionnaire [61]. A 5-point 
Likert scale ranging from [no problems] to [complete inability] is used to assess the health-related 
quality of life within each of the five dimensions (i.e., mobility, self-care, activities, pain/discomfort and 
anxiety/depression). The Brief Illness Perception Questionnaire (BIPQ) [62] evaluates the participants’ 
illness perception in an 8-item questionnaire. Items are scored on an ordinal scale ranging from zero [no 

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problems] to 10 [worst severity] [62]. The Patient Health Questionnaire-8 (PHQ-8) is an 8-item 
questionnaire used to evaluate the participants’ depressive symptoms [63]. Items are scored on a 4-
point Likert scale scoring frequency of experiencing symptoms of depression [63]. Also, a single item 
question for Patient’s Global Perceived Effect will be asked at all follow-ups, where participants are asked 
to rate improvement or deterioration of their LBP compared to before the intervention.  
 
Participants randomised to the SELFBACK DSS in addition to usual care are also asked a set of 
weekly tailoring questions used to individualise their self-management plan. The tailoring questions 
include items on pain (NRS for pain intensity [41]), function (item 5 from the Chronic Pain Grade 
Questionnaire [64]), kinesiophobia (1-item Tampa [65]), work ability (1-item WAI [54]), sleep (single 
item, modified from s-HUNT-Q [58]), pain self-efficacy (item 5 and 9 from PSEQ [66]), stress (4 items 
from PSS [60]), symptoms of depression (2 items from PHQ-8 [63]), and barriers for self-management 
(single item, customised to SELFBACK). In total, this comprises 17 tailoring questions; however, 
participants will only be asked a maximum of 7 questions per week (most commonly 4 questions). The 
selection of the relevant questions is based on a set of rules implemented in the backend of the DSS, 
taking into account the progression of the self-management process and the individual participant 
characteristics.  
 
5.   Statistics 
5.1. Sample size estimations 
The study is designed as a superiority trial with two parallel groups, SELFBACK in addition to usual care 
versus usual care only. We hypothesis that the intervention group (SELFBACK in addition to usual care) 
will have a two-point difference in pain related disability (RMDQ) compared to the control group (usual 
care) at three months follow-up. The sample size calculations have been performed in two ways. First, 
we conducted a simple calculation assuming only one follow-up measure and a standard deviation (SD) 
of the RMDQ score of six points. The expected SD was informed by previous high-quality studies in DK 
and UK investigating similar LBP populations [67-70]. Based on these calculations we estimated that a 
sample size of 382 (191 in each group) was necessary to detect a two-point difference with 90% power 
and a two-sided alpha level of 0.05.  
We then performed a simulation using 1000 repetitions of a mixed model regression for repeated 
measures, assuming 1) three data points per participant (i.e. baseline, six weeks and, three months), 2) 
an effect of treatment of two points, 3) a SD of six points, and 4) a correlation between repeated 
measures of 0.4. The latter was based on information from previous trials with repeated measures for 
the RMDQ in similar LBP populations [71, 72]. As in the simple calculations reported above, we used an 
alpha level of 0.05. Based on these assumptions, sample size calculations showed that 250 participants 
(i.e. 125 participants in each group) give a power of 92% (95% confidence interval [CI 90-93]) to detect a 
two-point difference in RMDQ between study groups at three months. Furthermore, simulations 
assuming a two-point difference between groups at both six weeks and three months indicated that a 
sample size of 180 (90 in each group) give a power of 94% (95% CI, 92-95). Taken together, these sample 
size calculations indicate that a sample size of ~250 persons (125 in each group) will be sufficient under 
the given assumptions if the statistical analyses utilise the repeated measure design. A recent 
systematic review showed that attrition rates ranged between 4-94% for digital self-management 
interventions lasting between two weeks and 12 months in LBP populations [25]. To allow for a 30% 

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drop out rate at three months follow-up we aim at including a total of 350 participants in the trial; 175 
participants in each arm. 
 
5.2. Statistical analysis 
The primary analysis will estimate the mean difference with a 95% confidence interval (CI) in RMDQ 
score at three months follow-up between groups (SELFBACK in addition to usual care versus usual care 
only). The analyses will be conducted according to the intention-to-treat principle using a linear mixed 
model for repeated measures. This model includes all available data for all participants at each time 
point (i.e. baseline, six weeks, and three months). In the regression model, individual participants will be 
specified as a random effect, accounting for the within subject covariance structure. The effect of group 
and time will be specified as fixed effects using a joint variable of intervention and time. Here, baseline 
levels are pooled over the two study groups assuming that any baseline differences are due to chance 
[73]; this also controls for any baseline differences in the outcome variable. The analysis will investigate 
the effect of the intervention as constant over time, as well as an interaction between time and group 
allocation. The between group difference will be estimated both in a crude model, and adjusted for the 
two variables used for stratification in the randomisation i.e. country and care provider [74]. Further 
adjustment for baseline levels of other prognostic factors will be considered. 
 
Any missing values are inherently accounted for in the mixed model approach [75], but multiple 
imputation methods and complete case analysis will be applied in sensitivity analyses. Possible 
modifiers of the effect of intervention on the primary outcome will be assessed in supplementary 
analyses stratified by gender, age groups, socioeconomic status and different levels of LBP severity etc., 
and accompanied by tests of statistical interaction.  
 
Secondary outcomes will be analysed using a similar approach as described above for the 
primary outcome, with linear mixed models for repeated measures. Analyses of data from six- and nine-
months follow-up will also be analysed according to the above description for the primary outcome. The 
precision of the estimates from the statistical analyses will be assessed by 95% CI. 
To increase the transparency, a statistical analysis plan will be agreed upon and made publicly 
available before the inclusion of participants is completed. Also, to reduce the risk of biased 
interpretation of results the following procedure will be undertaken: Two interpretations will be drafted 
based on a review of the primary outcome data with groups arbitrarily labelled as A and B [76]. One 
interpretation assumes that A is the selfBACK DSS in addition to usual care and B is usual care, the other 
interpretation assumes that A is the usual care and B is the selfBACK DSS in addition to usual care. After 
agreeing on both interpretations, the randomisation code is then broken and the correct interpretation 
will be chosen.  
 
6. Data collection  
The outlined data collection and data management is valid for the RCT and process evaluation (see 
section 8). 
6.1. Data collection  
Outcome measures are collected at baseline, six weeks, three, six and nine months. Data collection is 
performed online, and consequently all data are entered directly into the SELFBACK database by the 
participants. The website created for data collection has been extensively tested before the start of the 

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trial to ensure that all items of the outcome questionnaires are included, that the structure from the 
original questionnaires are kept in the online version, and that the scoring for each included 
questionnaire is consistent with the original scoring instructions. Time to complete the baseline 
questionnaire is approximately 20-25 minutes, the follow-up questionnaires are shorter and time to 
complete is approximately 20 min.  
For baseline, six weeks, three, six- and nine-month follow-up, participants will be sent an email with 
a link that directs them to logon to the SELFBACK questionnaire website using their username and 
password provided at the start of the trial. To ensure as high a response rate as possible in the follow-
up questionnaires, two reminder e-mails will be sent, the first after three days and the second after six 
days. If still no answer, a researcher will contact the participant via text-message or by phone call and 
ask if he/she is willing to answer the RMDQ on the phone.  
In addition to the outcomes obtained at baseline and follow-ups answered via the website, 
participants in the intervention group will answer a set of tailoring questions on a weekly basis in the 
app (described in section 3.2.1). These answers will be tracked over time as a separate dataset and used 
in secondary analysis of the trial data. 
 
 
6.2. Access to data 
Ownership of the data collected in the SELFBACK trial is shared between the participating partners 
(NTNU, GLA, RGU, TRX, NFA, HLE, UoSD). A data steering committee will be established, who will be 
competent to decide over the use of the data. The steering committee will comprise one member from 
each participating partner. The SELFBACK consortium supports the concept of data sharing and enquires 
from outside research partners to use the data are welcomed and will be discussed and decided upon 
by the steering committee. All personal identifiable data collected in the trial will be kept for five years. 
These data are kept to be able to track any adverse events reported post completion of the trial, and to 
enable the project to contact enrolled participants should any plan of additional long-term follow-up be 
funded. After this five-year period the data set will be fully anonymised. The anonymised full data set 
will be kept for up to 30 years for research purposes and will be used to create a data model that can 
inform the further development of a potential commercial version of the SELFBACK app. Data will be 
stored at NTNU, NO.  
 
7. Pilot testing 
A pilot study was conducted, starting August 2018 and ending January 2019. The primary reason for 
conducting the pilot study was to test a fully operative version of the SELFBACK app as well as to gain 
information about practical procedures regarding recruitment and screening as described in this 
protocol. Consequently, the pilot study provided information on the number of recruitment sites 
needed in each country and also identified challenges to the recruitment process that could be adjusted 
before the RCT.  
 
The pilot was conducted with the methods described for the RCT in this protocol. Recruitment 
ran until recruitment had been tested from all described channels. All participants in the pilot study 
were given the SELFBACK app in addition to usual care (intervention). Outcomes were collected at 
baseline and after 6 weeks. The outcome data collected will not be included in the RCT analyses. The 
pilot study also informed which variable was to be selected as a measure of adherence for the RCT. The 

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process evaluation (see section 8) was included in the pilot. Data on app usage and participants’ 
experiences with the app from interviews informed any adjustments needed in the app prior to the RCT.   
 
8. Process evaluation  
As an integrated part of the RCT, a process evaluation will be conducted, which explores how the digital 
self-management intervention will be implemented and received and used by participants. We intend to 
follow the RE-AIM framework [77]. The process evaluation will be informed by quantitative and 
qualitative data. The Virtual Climate Care Questionnaire (VCCQ) [78] (in a 15-item version) concerns 
perceived support for autonomy in a virtual care setting and three rating questions (on overall rating, 
ease of use and recommendation to others) using a 5-point system, will be collected. In addition to the 
questionnaires, data on physical activity (step count) and data analytics on app usage will be collected. 
Semi-structured interviews with a purposive sample of participants from both intervention and control 
groups from across DK and NO will be undertaken. These interviews will collect information from the 
participants about their experiences of self-management and, for the intervention group users, of using 
the SELFBACK app to promote self-management of LBP. The interviews will also explore barriers and 
facilitators to engagement with the SELFBACK app and embedding its use within daily routines. The 
qualitative components will be theoretically underpinned by the Normalization Process Theory [79, 80].  
Furthermore, adoption of the intervention by clinicians and their appraisal of the self-management 
plans generated by the DSS will be investigated through an electronic survey to all participating 
clinicians and semi-structured interviews with a purposive sample of participating clinicians.  
 
 
9. Trial management 
9.1. Research ethics approval 
Approvals for the pilot study, RCT and process evaluation have been obtained from the relevant ethical 
committees in DK and NO separately. In DK the approval was sought for from the Regional Scientific 
Ethical Committee for Southern Denmark and in NO from the Regional Committee for Medical and 
Health Research Ethics. Correspondingly, approval from institutional review boards and/or data 
protection agencies have been obtained in both DK and NO. In DK, approval was obtained from the 
Danish Data Protection Agency through application to the University of Southern Denmark’s legal office 
and in NO from the National Data Protection Authority.  
 
9.2. Protocol amendments 
Any amendments to the protocol will be registered with a detailed description of the change marked 
with date of implementation. Any amendments to the protocol will be filed with the relevant ethical 
committees or data protection agencies and registered at (www.clinicaltrials.gov) for transparency. 
 
9.3. Trial monitoring 
9.3.1. Harms 
No serious adverse events are expected for this trial. As the suggested self-management plans may 
include advice to increase physical activity and exercise volume, increased muscle soreness and 
transient increase in joint pain are expected. Such events are known in exercise interventions and as 
they are transient, they pose no harm to the participants. Additionally, participants are informed that 

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such events may occur and that they are normal. Furthermore, any detection of unusual pain increase is 
automatically noted and reacted to by the DSS, and a suggestion to adjust volume of physical activity or 
exercise and advice on handling muscle pain is given to the participant. In addition, within the app a 
“caution” checklist can be consulted if participants are experiencing worsening of symptoms or pain 
flare-ups. In the checklist, participants are advised to seek care with their primary HCP or emergency 
clinics as they normally would. Consequently, as serious adverse events are unexpected, no interim 
analysis or a priori defined stopping rules are defined or implemented for this trial.  
 For each country, all enquiries from participants reporting technical or medical problems are 
registered. The app contains a link to a webpage with Frequently Asked Questions (FAQ) that can guide 
participants with technical issues. Should a participant report any worsening of symptoms, the 
participant will be advised to seek care from their HCP as they normally would. All enquiries will be 
recorded and discussed in an internal audit and reported with the study results.  
 
9.3.2. Auditing 
On a regular basis, a researcher from each recruiting country (DK, NO), a representative from the app 
development company (TRX), a technical partner connected to the DSS system and primary investigator 
of the trial will review the recruitment, enrolment, data collection, conduct of the intervention, 
completion of the trial, reported adverse events and discuss appropriate actions to address any 
inconsistencies or unexpected events. The purpose of this internal audit is to detect any inconsistency 
between the planned trial conduct and the performed trial conduct as well as suggesting measures to 
address such inconsistencies.   
 
9.4. Declaration of interests 
The overall aim of the SELFBACK project is to develop a digital DSS and mobile app to support 
participants to self-manage their LBP. The results and experiences from the pilot and RCT will inform 
the further development of the app, which may be introduced into a commercial market. In order to 
secure an unbiased interpretation and dissemination of the RCT, the interpretation of the results will be 
performed blind to group allocation. Upon publication of study results, this commercial potential in the 
app development will be clearly stated and the publication will undergo peer-review to ensure 
methodological and scientific rigor. Additionally, the overall conduct of the trial is overseen by half-
yearly review from the European Union, who is funding the project. 
 
9.5. Dissemination policy 
The results of this RCT will be reported in accordance with the CONSORT 2010 reporting guideline and 
the 2013 amendment CONSORT-EHEALTH checklist for reporting web-based and mobile-based RCTs [2, 
81]. Data collection is expected to be complete by July 2020 and dissemination of trial results is planned 
from then. 
 
 
 
 

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