Overview

The study design is a multicentred RCT with embedded qualitative study and economic evaluation (see figure 1).

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Figure 1

Study flow chart. BOOST, Better Outcomes for Older people with Spinal Trouble; NHS, National Health Service; OPAL, Oxford Pain, Activity and Lifestyle; RCT, randomised controlled trial.

We are currently recruiting community-dwelling older adults with symptoms of NC. Recruitment opened on 25 July 2016 and we anticipate recruitment to be completed around June 2018. Participants are identified from National Health Service (NHS) physiotherapy and consultant spinal clinics in community and secondary care settings. In addition, participants are identified through a primary care-based cohort study (the Oxford Pain, Activity and Lifestyle (OPAL) cohort study). The OPAL cohort study is being conducted in the same localities as the trial.

The experimental intervention is a physiotherapist-delivered, combined physical and psychological programme. Participants attend an individual session, followed by 12 group sessions delivered over a 12-week period. During the individual session, participants undergo an assessment and are prescribed the exercises they will carry out during the group sessions tailored to their ability, symptom presentation and general health. The group sessions consist of (1) education and group discussion based on cognitive behavioural (CB) techniques; (2) warm-up and circuit exercises; and (3) a walking circuit. The education component focuses on pain management strategies, engagement with home exercises and increasing physical activity. The exercises target muscle strength, balance and flexibility, while the walking circuit aims to increase walking self-efficacy and mobility. The education component and supervised exercise are provided in groups of approximately six participants to maximise the potential for cost-effectiveness. There are two follow-up phone calls on completion of the group sessions to encourage adherence with the home exercise programme.

The comparator is advice given by a physiotherapist (best practice advice), ideally in one session, but up to two further review sessions are permissible. Advice includes self-management strategies, home exercises and encouragement to increase physical activity.

Participants are randomised in a 2:1 ratio (intervention:control) and followed up for 12 months (primary endpoint).

Eligibility

Participants are included in the trial if they fulfil the eligibility criteria listed in box 1. In the UK, the majority of adults are registered with a primary care practice. Due to the pragmatic nature of this trial, we include people with symptoms consistent with the clinical presentation of NC rather than a diagnosis of spinal stenosis based on evidence of narrowing of the spinal canal on an MRI scan. NC presents as a cluster of symptoms easily recognised using simple self-report questions identified in a recent systematic literature review3 (table 1). These questions have excellent sensitivity and specificity for identifying NC3 and are used to screen for eligible participants.

The exclusion criteria are largely related to the participant being unable to participate in the intervention, for example, if they are unable to follow instructions or mobilise short distances without assistance. Participants are not excluded on the basis of any existing comorbidities unless their general practitioner (GP) feels inclusion in the study places them at risk.

Approach

Potential participants are approached via two routes:

Eligibility screening

Potential participants identified via NHS spinal clinics or the OPAL cohort study are telephoned by the BOOST researcher (physiotherapists or research nurses) working at each site. During this telephone call, the researcher provides further information about the trial and completes initial eligibility checks. Eligible patients are invited to attend a research clinic appointment for a full assessment. If an individual requests to undertake the initial eligibility check in person, then this is arranged.

The research clinic appointment includes assessment of symptoms to ensure they are consistent with NC (using the questions in table 1), and screening for cauda equina syndrome or signs of serious pathology requiring immediate referral for investigations. Potential participants also undertake the Abbreviated Mental Test (AMT)14 to screen for cognitive impairment, which would make it difficult for a person to participate in the intervention. The AMT contains 10 items to assess orientation, registration, recall and concentration. This test can be used by any clinician and only takes 3–4 minutes to administer.15 A score of 6 or below (out of 10) suggests cognitive impairment requiring further assessment and patients are advised to consult their GP.15–17 A mobility assessment is undertaken if required to ensure the participant is able to mobilise independently at least 3 m unassisted (with or without a walking aid).

Informed consent

On completion of the full eligibility assessment, eligible participants are asked to provide written informed consent prior to enrolling them into the trial. The consent is taken by a researcher who has completed training in the consent procedures for the BOOST Trial.

Baseline assessment

After providing consent, the participant then completes a baseline questionnaire and undergoes a clinical assessment by the researcher. Data collection is described in table 2. There are a number of variables only collected at baseline for the purposes of providing descriptive data on the sample. The participant is weighed using digital scales wearing light, indoor clothing with their shoes removed. Weight is recorded to the nearest 0.1 kg. Height is measured using a stadiometer positioned against a wall. The participant stands on the platform, shoes removed, as upright as possible, hands by their side. The head plate of the stadiometer is lowered until it gently rests on the top of the participant’s head and the height is recorded in metres from the measuring rod, to the nearest 0.001 m (1 mm).

The participant provides self-reported data including the demographic variables listed in table 2, comorbidities including other pain problems (measured using the Nordic Pain Questionnaire18 19) and their current mobility status. Measures of mobility status include use of walking aids inside and outside, and self-rated walking speed.20 Change in mobility in the last year is measured using a 5-point scale constructed for the trial.

The STarT Back Screening Questionnaire21 is completed, allowing participants to be categorised according to their risk (low, medium or high) of developing persistent, disabling symptoms.21 Self-reported psychological factors with a potential impact on outcome are also collected. These include their confidence to exercise (Exercise Self-Efficacy Scale (short version)22) and their intention to carry out their home exercises using a question constructed for the trial (see table 2). Participants’ attitudes to the physical changes associated with ageing are measured using the Attitudes to Aging Questionnaire—physical changes subscale.23

Variables collected at follow-up are described in the Outcome measures section.

Imaging

Alongside the RCT, there is an exploration of whether MRI scan parameters along with other baseline factors moderate response to physiotherapy treatment. Indirect visualisation by MRI is the gold standard for diagnosing LSS when a patient presents with NC, and is always undertaken before surgery, but not necessarily before conservative treatment. Increasingly, GPs have open access to MRI, and if MRI were predictive of response to conservative treatment this could aid GPs’ clinical decision making. Despite the expense, there is remarkably little evidence about whether MRI scans can guide treatment choice effectively. Research evidence indicates that the fit between symptoms and MRI changes is poor.24 25 As MRI is currently the most common imaging investigation used, MRI data will be collected for all participants and we will systematically quantify the imaging characteristics. Pre-existing scans, taken in the 12 months preceding randomisation, will be used where possible to reduce the need for scanning.

Participants will be referred for an MRI study of the lumbar spine if they have not had one in the 12 months prior to randomisation. For these participants, the MRI scan will be taken after completion of other baseline data collection, and where possible before randomisation. Due to the nature of spinal stenosis, we would not expect spinal parameters to change markedly over a year-long period, hence the rationale for including existing scans. Practically, it is not possible to collect all MRI data prebaseline data collection as this may delay treatment and create unacceptable waiting times. For the subset of people who have MRI scans prior to randomisation, we will undertake formal subgroup analysis. We will explore other aspects of the relationship between functional outcomes and scan characteristics in additional analyses (not to be reported alongside the main trial results).

Consent for referral for a new MRI or use of an existing scan is obtained at the time of consent for the trial. Existing scans are transferred to a central repository for analysis in DICOM (Digital Imaging and Communications in Medicine) format.

The MRI data collection follows the protocol typical of NHS imaging departments. This is very similar across departments and efforts have been made to standardise the protocol where significant differences were identified.

We anticipate that a small number of participants will not have an MRI scan due to contraindications or by personal choice. Lack of an MRI scan does not exclude participants from the trial.

Randomisation and masking

Following baseline data collection, the researcher uses a web-based service to randomise the participants. During this process, the researcher is not informed of the treatment allocation. Instead, an automated email is sent directly to the physiotherapists who provide the interventions.

The web-based randomisation service is provided by the Oxford Clinical Trials Research Unit consistent with UK Clinical Research Collaboration (UKCRC) approved standard operating procedures, ensuring prospective registration and allocation concealment. Randomisation is stratified by centre, age (65–74 years and 75+ years) and gender. Participants are randomised in a 2:1 ratio (intervention:control) to ensure that there are enough participants to run a group intervention and minimise waiting times.

Physiotherapists delivering the interventions and participants cannot be masked to treatment allocation. All participants receive an initial 1-hour appointment. For those randomised to the BOOST programme, this is an assessment prior to attending the group sessions. For those randomised to the control arm, it is their initial physiotherapy session to deliver best practice advice. During this appointment, participants are informed of their treatment allocation by the physiotherapist. To ensure that researchers collecting follow-up data remain masked to treatment allocation, physiotherapists and participants are asked not to share information about treatment allocation with researchers.

The trial statistician and the research staff undertaking quality assurance checks and the qualitative study are not blinded to treatment allocation. The remaining members of the trial management team, including all those who are involved in data management, are masked to treatment allocation.

Outcome measures

Follow-up data are collected at 6 and 12 months after randomisation, at a clinic appointment. The outcomes are listed in table 2.

Self-reported measures

Self-reported measures related to symptoms and their impact include the Swiss Spinal Stenosis Questionnaire,27 Global Rating of Change,29 satisfaction with treatment using a 5-point scale constructed for the trial, health-related quality of life measured using the Euroquol 5 Dimension 5 Level Scale (EQ-5D-5L),30 and how well participants are managing their leg and back symptoms on a 10-point scale constructed for the trial.

Information is collected about cognitive and behavioural factors targeted during the intervention that are hypothesised to mediate the effects of the intervention. Fear avoidance is measured using the Fear Avoidance Beliefs Questionnaire.31 Self-efficacy is measured from different perspectives. Participants rate their confidence to walk half a mile using a single item from the Modified Gait Self-Efficacy Scale.32 To understand maintenance of exercise and physical activity, drawing on theoretical and empirical literature on this topic,33 participants also rate their confidence to restart their exercises having stopped them (self-efficacy recovery33 34) and their confidence to maintain their exercises in the long term (self-efficacy maintenance33 34). Measures related to the adherence of exercises and increasing physical activity are collected using the Index of Habit,35 self-reported frequency of exercise and satisfaction with their attempts to increase their physical activity36 measured on a 5-point scale constructed for the trial. Change in mobility in the last 6 months is measured using a 5-point scale constructed for the trial.

A range of measures are collected to capture constructs related to ageing. Frailty is measured using the Tilburg Frailty Index,37 and information about falls and fall-related injuries is collected as recommended by the Prevention of Falls Network Europe.38 Health resource use will be collected using the Client Service Receipt Inventory.39

Physical assessment

A measure of postural alignment is undertaken to quantify the degree of thoracic kyphosis.40 41 The participant removes their shoes and socks and stands as upright as possible, with their sacrum and back against the wall, with hands by their sides. The researcher measures the distance from the spinous process of the seventh cervical vertebrae to the wall using a ruler. It is an alternative to the occiput to wall measurement, but reflects kyphosis better as it minimises error due to head position.40 41

We then collect measures related to mobility, balance and strength, which are important targets of the intervention and markers related to ageing and frailty.

The Short Physical Performance Battery (SPPB)42 measures three aspects of physical performance: standing balance, walking speed and the time taken to perform five chair stands. An overall score is given by adding the scores for each test. Researchers follow published guidance on the test which is, briefly, as follows42:

Follow-up procedures

All participants are invited to attend a face-to face clinic appointment at 6 and 12 months. This is arranged by the researcher at each site. However, if a participant is unable to attend the clinic appointment, they are mailed a questionnaire that contains the primary outcome, all self-reported items and a participant completed version of the Client Service Receipt Inventory, but excludes the physical assessment. If the questionnaire is not returned within 2 weeks, then a second copy of the questionnaire is sent by the BOOST Trial Office as a reminder. If this is not returned within a further 2 weeks, then the BOOST Trial Office carries out a reminder phone call. After another 2 weeks, if the questionnaire has not been returned, then the BOOST Trial Office will attempt to contact the participant by telephone and collect core outcomes consisting of the primary outcome (ODI), pain troublesomeness rating, whether they are on a waiting list for spinal surgery, EQ-5D-5L, self-rated walking ability, falls and falls-related fractures, self-reported exercise adherence, and a brief version of the Client Service Receipt Inventory.

Adverse events

A safety reporting protocol has been developed to manage the reporting of related and unexpected serious adverse events (SAEs) and directly attributable adverse events (AEs). An AE is any untoward medical occurrence in a participant during a trial. There may or may not be a causal relationship with the trial intervention. AEs may be identified by the physiotherapists delivering the trial treatments or by researchers conducting follow-up assessments who have been trained in reporting procedures. SAEs must be reported to the trial management team within 24 hours of the physiotherapist or researcher becoming aware of the event. The Chief Investigator determines whether AEs require reporting to the Ethics Committee, Data Monitoring and Ethics Committee (DMEC) and Trial Sponsor.

Training and quality assurance of the research protocol

Researchers undergo approximately 4 hours of training covering eligibility screening, consent taking and data collection. They are provided with a manual containing detailed instructions for all trial procedures. All researchers undergo a quality assurance check to ensure they are following the trial protocol. This involves a BOOST team member observing the researcher carrying out the eligibility screening, taking consent and collecting trial data. Trial paperwork is checked for completeness. If any deviations from the protocol are identified, then further training is provided.

Study interventions

Physiotherapist training and quality assurance of intervention delivery

The interventions are delivered by physiotherapists registered with the Health and Care Professions Council. All physiotherapists delivering the BOOST programme attend a 1-day training course, are provided with an intervention manual and undertake 3 hours of online training. All physiotherapists delivering the control intervention attend 3 hours of training and are provided with an intervention manual. At some sites, the same physiotherapist delivers both arms of the trial. Both interventions are delivered according to a manualised protocol to reduce the risk of introducing bias to the study, and routine quality assurance checks are conducted. Visits are made to each site and at least one session of each intervention is observed. Feedback is provided to the physiotherapist on completion of the session and any issues or training needs identified. Another visit is arranged if substantial concerns are identified.

A structured checklist is used to monitor intervention delivery and ensure that all elements of the interventions are delivered as intended. We developed the education and discussion session of the BOOST programme with the assistance of a CB therapist who also assisted with training. The CB therapist helped to develop the checklist for the BOOST programme to ensure all the necessary components of the education and discussion section of the session were covered. The checklist is completed during the observed session. The education and discussion session may also be assessed via recording (depending on resources and BOOST staff capacity). All participants provide consent for sessions to be recorded for quality assurance purposes when they enrol in the study, and we seek verbal consent from the physiotherapist.

Following initial quality assurance checks and feedback, we also undertake fidelity assessments of both interventions that are not fed back to the physiotherapists. Feedback at this stage is not provided as we need to understand how this intervention would be delivered in the clinical setting if it were to be implemented.

A structured record of the interventions (treatment log) is completed by the physiotherapists and used to monitor fidelity. We collect attendance rates to monitor adherence with the interventions. Additional site visits will be conducted if any problems with intervention delivery are identified.

Sample size

At 80% power and 5% two-sided significance levels, the proposed sample size is 321 participants in total providing data at 12-month follow-up (214 in the intervention arm and 107 in the control arm), after which inflation for potential loss to follow-up (20%) yields an overall target of 402 (268 intervention, 134 control). If power is increased to 90%, then a sample size of 429 (286 in the intervention arm and 143 in the control arm) is required, after which inflation for potential loss to follow-up (20%) yields an overall target of 540 (360 intervention, 180 control).

These calculations have been based on the assumption that a between-group difference of five points is considered clinically significant on the ODI, with a baseline SD of 15, consistent with published estimates in older populations and those with NC.50 51 This yields a standardised difference of 0.33, a moderate effect size, which is consistent with being a reasonable target for a pragmatic trial.52

The loss to follow-up of 20% has been based on recent experiences of rehabilitation trials in older adults.53 We estimate that the therapist effects will be negligible from data that we have generated/published from a series of trials using similar standardised interventions. Our recent trials of hand exercises in rheumatoid arthritis and CB interventions in low back pain generated an intracluster correlation (ICC) of less than 0.0001.54 55 We anticipate about 20 therapists delivering the intervention, treating an average of 12–15 participants each. We have not incorporated a formal inflation for a therapist effect as the loss to follow-up allowance is generous and should mitigate against any moderate to large therapist effects.

The sample size is a minimum of 402 participants and a maximum of 540, to be finalised following a review of the sample size assumptions (in particular any evidence of clustering or a larger baseline SD) by the DMEC. A number of assumptions in the sample size estimate will be checked at this interim time point and adaptations made if needed, including the baseline SD of the ODI and the observed ICC. The DMEC will review these assumptions at this time point and make recommendations regarding the final sample size to the Trial Management Group and Programme Steering Committee (PSC). No interim analysis of the primary outcome will be performed.

Analysis

Data will be reported in accordance with the Consolidated Standards of Reporting Trials guidelines for RCTs and the appropriate extensions.56 A final statistical analysis plan will be developed by the end of the recruitment period, and we provide an outline description here. The primary analysis will be ‘intention to treat’, where participants will be included in their randomised groups. Effect estimates together with their 95% CIs will be reported. The primary outcome, ODI at 12 months, will be analysed using a linear multivariable regression multilevel method to take account of any therapist effect and adjusted for the region, baseline ODI score, stratification and important prognostic variables.

Missing data will be minimised by careful data management and training. The nature and mechanism for missing variables and outcomes will be investigated, and if appropriate multiple imputation will be used. Sensitivity analyses will be undertaken, assessing the underlying missing data assumptions.

A secondary complier average causal effect (CACE) analysis57 will explore the effect of adherence with the intervention (attendance and the participants’ engagement with the programme rated by the physiotherapist).58 For the purposes of the primary CACE analysis, we will define adherence as attending at least 9 out of the 12 sessions (75%). This would ensure that the majority of educational/discussion content is delivered. No one session is considered more important than another regarding educational/discussion content. Core CB concepts are introduced during the earlier sessions and are reiterated during subsequent sessions so attendance at nine sessions would ensure all core content is covered. Attendance at nine sessions will ensure that the participant is introduced to the home exercise programme and has undertaken the exercise programme for a minimum of 6 weeks (sessions 1–9 are delivered over a 6-week period). Six weeks of strength training has been shown to be sufficient to result in short-term improvements in muscle strength and physical function.59–61

We have also defined a priori subgroup criteria based on the published literature and will explore treatment effects by age (65–74 years/75+ years), gender (male/female), Tilburg Frailty Index scores (0–4/5+),37 Fear Avoidance Beliefs Questionnaire scores (0–14/15+),62 STarT Back Risk Stratification score (low-risk/medium-risk/high-risk groups),21 hand grip strength (men: <30/30+; women <20/20+)63 and SPPB scores (SPPB 0–6 low performance; SPPB 7–9 intermediate performance; SPPB 10–12 high performance63). Among participants who have an MRI scan prior to randomisation, we will estimate treatment effects in two subgroups defined by MRI parameters (cross-sectional spinal canal area cut-point of 100 mm²).26 Subgroup effects will be analysed using interaction with treatment tests and will be displayed using forest plots.64

We will carry out a series of additional exploratory subgroup and interaction analyses to identify other MRI scan parameters and baseline factors that predict change in ODI scores between baseline and 12 months. Interaction and polynomial terms will be considered when carrying out the exploratory analysis, and the analyses may be based on continuous or binary cut-points. These models will report variables that predict the outcome at 12 months with 95% CIs and p value. These additional analyses will be presented in secondary publications and with appropriate caveats about the interpretation of exploratory subgroup analyses.

Further supplementary analysis may include mediation analysis to evaluate treatment mechanisms, and exploratory analyses of exercise dose effects including profiling of treatment response trajectories. These are a priori analyses based on the logic model used to develop the intervention, and will examine (1) whether the intervention affects the hypothesised mediators as intended, (2) whether changes in the hypothesised mediators relate to changes in outcomes, and (3) whether the effects of the intervention on the outcomes are attributable to changes in the hypothesised causal pathway.

Economic evaluation

A prospective economic evaluation, conducted from an NHS and personal social services perspective, is integrated into the trial design. The economic evaluation will estimate the difference in the cost of resources used by participants in the two arms of the trial, enabling costs and consequences to be compared between alternative forms of physiotherapy. The economic assessment method will adhere to the recommendations of the National Institute for Health and Care Excellence Reference Case.65

We will estimate the costs of delivering the intervention, including development and training, the cost of delivering sessions, and participant follow-up/management. Broader resource utilisation is captured through two principal sources: (1) participant interview administered at 6 and 12 months postrandomisation and (2) routine health service data collection systems (Hospital Episode Statistics). Unit costs for health and social care resources will be derived from local and national sources.66 Costs will be standardised to current prices where possible. Health-related quality of life will be measured at baseline and at 6 and 12 months postrandomisation using the generic EuroQol EQ-5D-5L; national tariff sets will be used to generate quality-adjusted life-years (QALYs).67–69 We will in the first instance use self-report of the EuroQol EQ-5D-5L measure. Multiple imputation methods will be used to impute missing data and avoid biases associated with complete case analysis.70 The results of the economic evaluation will be expressed in terms of incremental cost per QALY gained. Non-parametric bootstrap estimation will be used to derive 95% CIs for the mean cost and QALY differences between the trial groups, as well as to populate a cost-effectiveness plane. A series of sensitivity analyses will be undertaken to explore the implications of uncertainty on the incremental cost-effectiveness ratios and to consider the broader issue of the generalisability of the study results. The full details of the economic evaluation will be described in the health economic analysis plan.

Qualitative study

The aim of the qualitative study is to better understand participant experiences both of living and ageing with NC, and their experience of the interventions delivered during the trial. Understanding the experiences of the participants will inform strategies for implementation if the intervention is clinically effective.

All participants recruited to the trial are eligible. As part of the consent process for the trial, participants are informed about the interview study and asked if they are willing to be contacted by a researcher to receive more information. Participants who agree are provided with an additional information sheet and contacted by the qualitative research team. Prior to starting the first interview, written consent is sought. Consent is reaffirmed verbally prior to each follow-up telephone interview.

We are interviewing participants at three time points over the course of the trial in order to capture physical, psychological, social and contextual changes. Topics explored include current impact of NC on day-to-day life and well-being, beliefs about the role of exercise in ameliorating symptoms, the role of exercise on slowing/reversing physical decline, and how these beliefs impact on adherence to the treatments.

We estimate 60 participants will be required to ensure data saturation is reached in all three interviews while ensuring diversity of participants by age, gender, ethnicity and intervention arm, allowing for attrition over the course of the study.71 72 In any one recruitment site interview participants are recruited consecutively, and as recruitment proceeds sampling is adjusted to ensure diversity of age, gender, ethnicity and intervention arm.

Interviews are semistructured using prespecified open-ended questions. The interviewer uses prompts to further investigate responses and allows the participant to explore topics they feel are relevant.71 73 The first interview takes place at a location convenient to the participant, usually their home. The second and third interviews are telephone interviews to reduce resource implications for the project. However, if a telephone conversation is unfeasible (eg, poor hearing), then subsequent interviews are conducted face to face.

The first interview takes place between randomisation and starting treatment. Participants do not yet know their treatment allocation. Questions focus on the impact of NC on the participant’s physical and psychosocial health, their beliefs around exercise and ageing, and concerns and hopes regarding the intervention. The interview takes up to 90 min and is audio-recorded.

The second interview is approximately 1 month after completing treatment. Topics explored include the participant’s experiences of the intervention, adherence to home exercises, and any changes in their symptoms, exercise and ageing beliefs, physical activity levels, or life circumstances. The third interview coincides with the 12-month follow-up assessment and further explores these topics, and how they may have changed after an extended period of self-management. Interview schedules are adapted to account for data captured in earlier interviews, and the interviewer has access to the outcome measures for each interviewee for exploration during the interview. The telephone interviews are recorded, and notes are transcribed by the interviewer from the audio recordings.

Audio recordings of first interviews are transcribed verbatim by an independent transcriber, anonymised and allocated an ID number. The telephone interview notes are checked against the audio recordings and linked to the first interview through the ID number. Participants are sent a copy of the transcripts if requested, and may delete any information they would not like to be used.

All transcripts are imported into NVivo and analysed using thematic analysis.74 Coding is undertaken as each transcript is received. We will undertake cross-case analysis.75 To understand trajectories of change in relation to back pain and NC, we will undertake longitudinal case comparative analysis, an approach to analysis used previously by the research team.76

Trial management

This trial is run by a UKCRC fully registered clinical trials unit, according to approved and audited standard operating procedures. All trial staff undergo regular training to ensure they are compliant with Good Clinical Practice and other relevant legislation and the requirements such as the Data Protection Act.

Data management and checking

All data are processed according to the Data Protection Act 1998 and all documents are stored safely in confidential conditions. Each participant is provided with a unique trial identification number. Data are entered manually onto the trial database (OpenClinica). The BOOST Trial Office reviews all data collection forms for completeness and accuracy using automated validation checks, querying missing and nonsensical data with sites, according to trial-specific procedures which have been developed to ensure data quality.

Patient and public involvement

During the application process for this trial, we assembled a patient and public involvement (PPI) group and we have continued to work closely with them. JuF is the lead PPI representative and a coapplicant and contributed to the design of the trial. We appointed a PPI representative to be an independent member of the PSC. PPI engagement has been undertaken in face-to-face meetings and via emails and phone calls to make it as convenient as possible for the PPI group to contribute. PPI representatives have assisted with the development of the physiotherapy intervention. Two PPI representatives attended the intervention development day along with clinicians and researchers. One PPI representative carried out the proposed exercise programme in her home so she could give feedback on the practicalities of performing the proposed programme. PPI representatives helped us to develop the patient materials for the intervention.

PILs, consent forms and posters advertising the trial have been reviewed by the PPI group and they have provided feedback on the layout and wording. We have piloted questionnaires with our PPI group. PPI representatives have helped with developing interview schedules for the qualitative study, and we have carried out some practice interviews with the PPI representatives prior to undertaking the actual study.