Evaluating the quality of subgroup analyses in randomized controlled trials of therapist-delivered interventions for nonspecific low back pain: a systematic review

Interaction analyses: Enhancing understanding of chronic low back pain

BACKGROUND

Chronic low back pain (CLBP) is complex. Statistical examination of influences of exposures (e.g. characteristics) upon outcomes (e.g. pain) facilitates understanding of complexity and personalized care. Psychological factors may be associated with higher disability following exercise in CLBP. Examining interactions of psychological variables with exercise on disability might further understanding of CLBP.

OBJECTIVES

Secondary analysis of data from a CLBP cohort evaluating interactions between psychological variables and exercise on disability.

DESIGN

Longitudinal cohort study.

METHOD

Variables from a published prognostic model for disability: disability (baseline/one-year follow-up), psychological principal component scores (principal component score two (PC2) - Fear-avoidance beliefs, pain catastrophizing, pain self-efficacy; principal component score three (PC3) - thought suppression, behavioral endurance), exercise (during follow-up), forward-bending time, punishing significant other responses. Differences between exercisers and non-exercisers were assessed using Chi-Squared/Mann-Whitney tests. Multivariable linear regression models for follow-up disability included a term examining interaction between principal component scores and exercise.

RESULTS

Exercisers had significantly different scores for PC2 (p = .02) and PC3 (p = .03), lower baseline (p = .005) and follow-up pain intensity (p < .001), follow-up disability (p < .001) and faster forward-bend times (p = .014). There was no significant interaction between exercise and PC2 (p = .92) or PC3 (p = .75).

CONCLUSIONS

This study showed no interaction between psychological factors and exercise on disability at follow-up. These findings suggest that the disability outcome of people with CLBP who undertake exercise as an intervention does not differ from those who do not undertake exercise, irrespective of their baseline psychological status.

The Effect of Lumbar Belts with Different Extensibilities on Kinematic, Kinetic, and Muscle Activity of Sit-to-Stand Motions in Patients with Nonspecific Low Back Pain

Although lumbar belts can be used for the treatment and prevention of low back pain, the role of the lumbar belt remains unclear without clear guidelines. This study aimed to investigate the effect of lumbar belts with different extensibilities on the kinematics, kinetics, and muscle activity of sit-to-stand motions in terms of motor control in patients with nonspecific low back pain. A total of 30 subjects participated in the study: 15 patients with nonspecific low back pain and 15 healthy adults. Participants performed the sit-to-stand motion in random order of three conditions: no lumbar belt, wearing an extensible lumbar belt, and wearing a non-extensible lumbar belt. The sit-to-stand motion's kinematic, kinetic, and muscle activity variables in each condition were measured using a three-dimensional motion analysis device, force plate, and surface electromyography. An interaction effect was found for the time taken, anterior pelvic tilt angle, and muscle activity of the vastus lateralis and biceps femoris. The two lumbar belts with different extensibilities had a positive effect on motor control in patients with nonspecific low back pain. Therefore, both types of extensible lumbar belts can be useful in the sit-to-stand motion, which is an important functional activity for patients with nonspecific low back pain.

Do recommended interventions widen or narrow inequalities in musculoskeletal health? An equity-focussed systematic review of differential effectiveness

Background

It is unclear whether seven interventions recommended by Public Health England for preventing and managing common musculoskeletal conditions reduce or widen health inequalities in adults with musculoskeletal conditions.

Methods

We used citation searches of Web of Science (date of ‘parent publication’ for each intervention to April 2021) to identify original research articles reporting subgroup or moderator analyses of intervention effects by social stratifiers defined using the PROGRESS-Plus frameworks. Randomized controlled trials, controlled before-after studies, interrupted time series, systematic reviews presenting subgroup/stratified analyses or meta-regressions, individual participant data meta-analyses and modelling studies were eligible. Two reviewers independently assessed the credibility of effect moderation claims using Instrument to assess the Credibility of Effect Moderation Analyses. A narrative approach to synthesis was used (PROSPERO registration number: CRD42019140018).

Results

Of 1480 potentially relevant studies, seven eligible analyses of single trials and five meta-analyses were included. Among these, we found eight claims of potential differential effectiveness according to social characteristics, but none that were judged to have high credibility.

Conclusions

In the absence of highly credible evidence of differential effectiveness in different social groups, and given ongoing national implementation, equity concerns may be best served by investing in monitoring and action aimed at ensuring fair access to these interventions.

The quality of subgroup analyses in chronic pain randomized controlled trials: a methodological review

The quality of subgroup analyses (SGAs) in chronic non-cancer pain trials is uncertain. The purpose of this study was to address this issue. We conducted a comprehensive search in MEDLINE and EMBASE from January 2012 to September 2018 to identify eligible trials. Two pairs of reviewers assessed the quality of the SGAs and the credibility of subgroup claims using the 10 criteria developed by Sun et al. in 2012. The associations between the quality of the SGAs and the studies' characteristics including risk of bias, funding sources, sample size, and the latest impact factor, were assessed using multivariable logistic regression. Our search retrieved 3,401 articles of which 66 were eligible. The total number of SGAs was 177 of which 52 (29.4%) made a subgroup claim. Of these, only 15 (8.5%) were evaluated as being of high quality. Among the 30 SGAs that claimed subgroup effects using an appropriate method of performing interaction tests, the credibility of only 5 were assessed as high. None of the subgroup claims met all the credibility criteria. No significant association was found between the quality of SGAs and the studies' characteristics. The quality of the SGAs performed in chronic pain trials was poor. To enhance the quality of SGAs, scholars should consider the developed criteria when designing and conducting trials, particularly those which need to be specified a priori .

Identification of subgroup effect with an individual participant data meta-analysis of randomised controlled trials of three different types of therapist-delivered care in low back pain

Background

Proven treatments for low back pain, at best, only provide modest overall benefits. Matching people to treatments that are likely to be most effective for them may improve clinical outcomes and makes better use of health care resources.

Methods

We conducted an individual participant data meta-analysis of randomised controlled trials of three types of therapist delivered interventions for low back pain (active physical, passive physical and psychological treatments). We applied two statistical methods (recursive partitioning and adaptive risk group refinement) to identify potential subgroups who might gain greater benefits from different treatments from our individual participant data meta-analysis.

Results

We pooled data from 19 randomised controlled trials, totalling 9328 participants. There were 5349 (57%) females with similar ratios of females in control and intervention arms. The average age was 49 years (standard deviation, SD, 14).

Participants with greater psychological distress and physical disability gained most benefit in improving on the mental component scale (MCS) of SF-12/36 from passive physical treatment than non-active usual care (treatment effects, 4.3; 95% confidence interval, CI, 3.39 to 5.15). Recursive partitioning method found that participants with worse disability at baseline gained most benefit in improving the disability (Roland Morris Disability Questionnaire) outcome from psychological treatment than non-active usual care (treatment effects, 1.7; 95% CI, 1.1 to 2.31). Adaptive risk group refinement did not find any subgroup that would gain much treatment effect between psychological and non-active usual care. Neither statistical method identified any subgroups who would gain an additional benefit from active physical treatment compared to non-active usual care.

Conclusions

Our methodological approaches worked well and may have applicability in other clinical areas. Passive physical treatments were most likely to help people who were younger with higher levels of disability and low levels of psychological distress. Psychological treatments were more likely to help those with severe disability. Despite this, the clinical importance of identifying these subgroups is limited. The sizes of sub-groups more likely to benefit and the additional effect sizes observed are small. Our analyses provide no evidence to support the use of sub-grouping for people with low back pain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04028-8.

Subgroup analysis in haematologic malignancies phase III clinical trials: A systematic review

AIMS

To assess the appropriateness of the use and interpretation of subgroup analysis in haematology randomized clinical trials (RCTs).

METHOD

A systematic review of Medline, including haematology phase III RCTs published between January 2013 and October 2019, was carried out to identify reported subgroup analysis. Information related to trial characteristics, subgroup analysis and claims of subgroup difference were collected.

RESULTS

The initial search identified 1622 studies. A total of 98 studies reporting subgroup analyses were identified. Of those, 24 RCT reported 46 claims of subgroup difference. Among them, 44 were claims for the primary outcome, of which 25 were considered strong claims and 17 were considered suggestions of a possible effect. Authors included subgroup variables for the primary outcome measured at baseline for 38 claims (n = 86.36%), used a subgroup variable as a stratification factor at randomization for 15 (34.09%), clearly prespecified their hypothesis for 11 (25%), the subgroup effect was one of a small number of hypothesised effects tested (≤ 5) for 17 (38.64%), carried out a test of interaction that provide statistically significant for 18 (40.91%), documented replication of a subgroup effect with previously related studies for 11 (25%), identified the consistency of a subgroup effect across related outcome for 10 (22.72%) and provided a biological rationale for the effect for 8 (18.18%). Of the 44 claims for the primary outcome, 34 (77.27%) met four or fewer of the 10 credibility criteria.

CONCLUSION

The subgroup claims reported in haematology RCTs lack credibility, even when the claims are strong. Information about subgroup difference should be interpreted cautiously.

Characteristics and interpretation of subgroup analyses based on tumour characteristics in randomised trials testing target-specific anticancer drugs: design of a systematic survey

BACKGROUND

Target-specific anticancer drugs are under rapid development. Little is known, however, about the risk of administering target-specific drugs to patients who have tumours with molecular alterations or other characteristics that can make the drug ineffective or even harmful. An increasing number of randomised clinical trials (RCTs) investigating target-specific anticancer drugs include subgroup analyses based on tumour characteristics. Such subgroup analyses have the potential to be more credible and influential than subgroup analyses based on traditional factors such as sex or tumour stage. In addition, they may more frequently lead to qualitative subgroup effects, that is, show benefit in one but harm in another subgroup of patients (eg, if the tumour characteristic makes the drug ineffective or even enhance tumour growth). If so, subgroup analyses based on tumour characteristics would be highly relevant for patient safety. The aim of this study is to systematically assess the frequency and characteristics of subgroup analyses based on tumour characteristics, the frequency of qualitative subgroup effects, their credibility, and the interpretations that investigators and guidelines developers report.

METHODS AND ANALYSIS

We will perform a systematic survey of 433 RCTs testing the effect of target-specific anticancer drugs. Teams of methodologically trained investigators and oncologists will identify eligible studies, extract relevant data and assess the credibility of putative subgroup effects using a recently developed formal instrument. We will systematically assess how trial investigators interpret apparent subgroup effects based on tumour characteristics and the extent to which they influence subsequent practice guidelines. Our results will provide empirical data characterising an increasingly used type of subgroup analysis in cancer trials and its potential impact on precision medicine to predict benefit or harm.

ETHICS AND DISSEMINATION

Formal ethical approval is not required for this study. We will disseminate the findings in a peer-reviewed and open-access journal publication.

Exercise treatment effect modifiers in persistent low back pain: an individual participant data meta-analysis of 3514 participants from 27 randomised controlled trials

Background

Low back pain is one of the leading causes of disability worldwide. Exercise therapy is widely recommended to treat persistent non-specific low back pain. While evidence suggests exercise is, on average, moderately effective, there remains uncertainty about which individuals might benefit the most from exercise.

Methods

In parallel with a Cochrane review update, we requested individual participant data (IPD) from high-quality randomised clinical trials of adults with our two primary outcomes of interest, pain and functional limitations, and calculated global recovery. We compiled a master data set including baseline participant characteristics, exercise and comparison characteristics, and outcomes at short-term, moderate-term and long-term follow-up. We conducted descriptive analyses and one-stage IPD meta-analysis using multilevel mixed-effects regression of the overall treatment effect and prespecified potential treatment effect modifiers.

Results

We received IPD for 27 trials (3514 participants). For studies included in this analysis, compared with no treatment/usual care, exercise therapy on average reduced pain (mean effect/100 (95% CI) −10.7 (−14.1 to –7.4)), a result compatible with a clinically important 20% smallest worthwhile effect. Exercise therapy reduced functional limitations with a clinically important 23% improvement (mean effect/100 (95% CI) −10.2 (−13.2 to –7.3)) at short-term follow-up. Not having heavy physical demands at work and medication use for low back pain were potential treatment effect modifiers—these were associated with superior exercise outcomes relative to non-exercise comparisons. Lower body mass index was also associated with better outcomes in exercise compared with no treatment/usual care. This study was limited by inconsistent availability and measurement of participant characteristics.

Conclusions

This study provides potentially useful information to help treat patients and design future studies of exercise interventions that are better matched to specific subgroups.

Protocol publication

https://doi.org/10.1186/2046-4053-1-64

The Evolving Case Supporting Individualised Physiotherapy for Low Back Pain

Low-back pain (LBP) is one of the most burdensome health problems in the world. Guidelines recommend simple treatments such as advice that may result in suboptimal outcomes, particularly when applied to people with complex biopsychosocial barriers to recovery. Individualised physiotherapy has the potential of being more effective for people with LBP; however, there is limited evidence supporting this approach. A series of studies supporting the mechanisms underpinning and effectiveness of the Specific Treatment of Problems of the Spine (STOPS) approach to individualised physiotherapy have been published. The clinical and research implications of these findings are presented and discussed. Treatment based on the STOPS approach should also be considered as an approach to individualised physiotherapy in people with LBP.

Model Simulations Challenge Reductionist Research Approaches to Studying Chronic Low Back Pain

BACKGROUND

Traditionally, low back pain (LBP) is studied using a reductionist approach, in which the factors contributing to the clinical presentation of LBP are studied in isolation to identify the primary pathology or condition linked to LBP. We argue that reductionism may not be suitable for studying LBP, considering the complex, multifactorial nature of this condition.

OBJECTIVES

To quantify the likelihood of successfully subclassifying patients with LBP and effectively targeting treatment based on a single dominant factor contributing to LBP.

METHODS

Both analytical and numerical simulations (Monte Carlo) of 1 million patients with LBP were performed. Several factors contributing to LBP were randomly assigned to each individual. The following outcome measures were computed, as a function of the number of factors: the percentage of individuals who could be subclassified by identifying a single factor exceeding a certain threshold, and the average reduction in LBP when treatment eliminates the largest contributing factor versus a multimodal treatment that eliminates a number of the randomly selected factors.

RESULTS

With an increasing number of factors, the probability of subclassifying an individual to a subgroup based on a single factor tends toward zero. A multimodal treatment arbitrarily addressing any 2 or more factors was more effective than diagnosing and treating a single factor that maximally contributed to LBP.

CONCLUSION

Results suggest that reductionism is not appropriate for subclassifying patients with LBP or for targeting treatment. The use of reductionist approaches may explain some of the challenges when creating LBP classification systems and designing effective treatment interventions. J Orthop Sports Phys Ther 2019;49(6):477-481. Epub 15 May 2019. doi:10.2519/jospt.2019.8791.

Analysis of Motor Control in Patients With Low Back Pain: A Key to Personalized Care?

Motor control exercise has been shown to be effective in the management of low back pain (LBP). However, the effect sizes for motor control exercise are modest, possibly because studies have used a one-size-fits-all approach, while the literature suggests that patients may differ in presence or type of motor control issues. In this commentary, we address the question of whether consideration of such variation in motor control issues might contribute to more personalized motor control exercise for patients with LBP. Such an approach is plausible, because motor control changes may play a role in persistence of pain through effects on tissue loading that may cause nociceptive afference, particularly in the case of peripheral sensitization. Subgrouping systems used in clinical practice, which comprise motor control aspects, allow reliable classification that is, in part, aligned with findings in studies on motor control in patients with LBP. Motor control issues may have heuristic value for treatment allocation, as the different presentations observed suggest different targets for motor control exercise, but this remains to be proven. Finally, clinical assessment of patients with LBP should take into account more aspects than motor control alone, including pain mechanisms, musculoskeletal health, and psychosocial factors, and may need to be embedded in a stratification approach based on prognosis to avoid undue diagnostic procedures. J Orthop Sports Phys Ther 2019;49(6):380-388. Epub 12 Jun 2018. doi:10.2519/jospt.2019.7916.

A systematic survey identified 36 criteria for assessing effect modification claims in randomized trials or meta-analyses

OBJECTIVE

The objective of the study was to systematically survey the methodological literature and collect suggested criteria for assessing the credibility of effect modification and associated rationales.

STUDY DESIGN AND SETTING

We searched MEDLINE, Embase, and WorldCat up to March 2018 for publications providing guidance for assessing the credibility of effect modification identified in randomized trials or meta-analyses. Teams of two investigators independently identified eligible publications and extracted credibility criteria and authors' rationale, reaching consensus through discussion. We created a taxonomy of criteria that we iteratively refined during data abstraction.

RESULTS

We identified 150 eligible publications that provided 36 criteria and associated rationales. Frequent criteria included significant test for interaction (n = 54), a priori hypothesis (n = 49), providing a causal explanation (n = 47), accounting for multiplicity (n = 45), testing a small number of effect modifiers (n = 38), and prespecification of analytic details (n = 39). For some criteria, we found more than one rationale; some criteria were connected through a common rationale. For some criteria, experts disagreed regarding their suitability (e.g., added value of stratified randomization; trustworthiness of biologic rationales).

CONCLUSION

Methodologists have expended substantial intellectual energy providing criteria for critical appraisal of apparent effect modification. Our survey highlights popular criteria, expert agreement and disagreement, and where more work is needed, including testing criteria in practice.

Guideline recommendations on the pharmacological management of non-specific low back pain in primary care - is there a need to change?

INTRODUCTION

Analgesic drugs are often prescribed to patients with non-specific low back pain (NSLBP). Recommendations for non-invasive pharmacological management of NSLBP from recent clinical practice guidelines were compared with each other and with the best available evidence on drug efficacy. Areas covered: Recommendations concerning opioids, non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, antidepressants, anticonvulsants and muscle relaxants from national primary care guidelines published within the last 3 years were included in this review. For each pharmacological treatment, the most recent systematic review was included as the best available evidence on drug efficacy and common adverse effects were summarized. Expert opinion: Although differences exist between guidelines, publications are universally moving away from pharmacotherapy due to the limited efficacy and the risk of adverse effects. NSAIDs have replaced paracetamol as the first choice analgesics for NSLBP in many guidelines. Opioids are generally considered to be a last resort, but opioid prescriptions have been increasing over recent years. Upcoming guideline updates should explicitly shift their focus from pain to function and from pharmacotherapy to non-pharmacological treatments; patient education is important to make sure NSLBP patients accept these changes. To improve the quality of NSLBP care, the evidence-practice gap should be closed through guideline implementation strategies.

A recursive partitioning approach for subgroup identification in individual patient data meta-analysis

Background

Motivated by the setting of clinical trials in low back pain, this work investigated statistical methods to identify patient subgroups for which there is a large treatment effect (treatment by subgroup interaction). Statistical tests for interaction are often underpowered. Individual patient data (IPD) meta‐analyses provide a framework with improved statistical power to investigate subgroups. However, conventional approaches to subgroup analyses applied in both a single trial setting and an IPD setting have a number of issues, one of them being that factors used to define subgroups are investigated one at a time. As individuals have multiple characteristics that may be related to response to treatment, alternative exploratory statistical methods are required.

Methods

Tree‐based methods are a promising alternative that systematically searches the covariate space to identify subgroups defined by multiple characteristics. A tree method in particular, SIDES, is described and extended for application in an IPD meta‐analyses setting by incorporating fixed‐effects and random‐effects models to account for between‐trial variation. The performance of the proposed extension was assessed using simulation studies. The proposed method was then applied to an IPD low back pain dataset.

Results

The simulation studies found that the extended IPD‐SIDES method performed well in detecting subgroups especially in the presence of large between‐trial variation. The IPD‐SIDES method identified subgroups with enhanced treatment effect when applied to the low back pain data.

Conclusions

This work proposes an exploratory statistical approach for subgroup analyses applicable in any research discipline where subgroup analyses in an IPD meta‐analysis setting are of interest.

Who Benefits Most From Individualized Physiotherapy or Advice for Low Back Disorders? A Preplanned Effect Modifier Analysis of a Randomized Controlled Trial

STUDY DESIGN

A preplanned effect modifier analysis of the Specific Treatment of Problems of the Spine randomized controlled trial.

OBJECTIVE

To identify characteristics associated with larger or smaller treatment effects in people with low back disorders undergoing either individualized physical therapy or guideline-based advice.

SUMMARY OF BACKGROUND DATA

Identifying subgroups of people who attain a larger or smaller benefit from particular treatments has been identified as a high research priority for low back disorders.

METHODS

The trial involved 300 participants with low back pain and/or referred leg pain (≥6 wk, ≤6 mo duration), who satisfied criteria to be classified into five subgroups (with 228 participants classified into three subgroups relating to disc-related disorders, and 64 classified into the zygapophyseal joint dysfunction subgroup). Participants were randomly allocated to receive either two sessions of guideline based advice (n = 144), or 10 sessions of individualized physical therapy targeting pathoanatomical, psychosocial, and neurophysiological factors (n = 156). Univariate and multivariate linear mixed models determined the interaction between treatment group and potential effect modifiers (defined a priori) for the primary outcomes of back pain, leg pain (0-10 Numeric Rating Scale) and activity limitation (Oswestry Disability Index) over a 52-week follow-up.

RESULTS

Participants with higher levels of back pain, higher Örebro scores (indicative of higher risk of persistent pain) or longer duration of symptoms derived the largest benefits from individualized physical therapy relative to advice. Poorer coping also predicted larger benefits from individualized physical therapy in the univariate analysis.

CONCLUSION

These findings suggest that people with low back disorders could be preferentially targeted for individualized physical therapy rather than advice if they have higher back pain levels, longer duration of symptoms, or higher Örebro scores.

LEVEL OF EVIDENCE

2.

Non-specific low back pain

Non-specific low back pain affects people of all ages and is a leading contributor to disease burden worldwide. Management guidelines endorse triage to identify the rare cases of low back pain that are caused by medically serious pathology, and so require diagnostic work-up or specialist referral, or both. Because non-specific low back pain does not have a known pathoanatomical cause, treatment focuses on reducing pain and its consequences. Management consists of education and reassurance, analgesic medicines, non-pharmacological therapies, and timely review. The clinical course of low back pain is often favourable, thus many patients require little if any formal medical care. Two treatment strategies are currently used, a stepped approach beginning with more simple care that is progressed if the patient does not respond, and the use of simple risk prediction methods to individualise the amount and type of care provided. The overuse of imaging, opioids, and surgery remains a widespread problem.

Subgrouping Patients With Nonspecific Low Back Pain: Hope or Hype?

Clinicians and clinical researchers share a common goal of achieving better outcomes for patients with low back pain (LBP). For that, randomized controlled trials and systematic reviews are the most reliable study designs to determine the effects of interventions. Subgroup analyses in these research designs have been used to examine treatment-effect modification across subgroups defined by patient characteristics. In this Viewpoint, the authors present supporting and opposing arguments for the subgrouping approach in nonspecific LBP, considering the progress made so far in the LBP field and the relevant literature in adjacent fields. J Orthop Sports Phys Ther 2017;47(2):44-48. doi:10.2519/jospt.2017.0602.

Development of a repository of individual participant data from randomized controlled trials of therapists delivered interventions for low back pain

Background

Individual patient data (IPD) meta‐analysis of existing randomized controlled trials (RCTs) is a promising approach to achieving sufficient statistical power to identify sub‐groups. We created a repository of IPD from multiple low back pain (LBP) RCTs to facilitate a study of treatment moderators. Due to sparse heterogeneous data, the repository needed to be robust and flexible to accommodate millions of data points prior to any subsequent analysis.

Methods

We systematically identified RCTs of therapist delivered intervention for inclusion to the repository. Some were obtained through project publicity. We requested both individual items and aggregate scores of all baseline characteristics and outcomes for all available time points. The repository is made up of a hybrid database: entity‐attribute‐value and relational database which is capable of storing sparse heterogeneous datasets. We developed a bespoke software program to extract, transform and upload the shared data.

Results

There were 20 datasets with more than 3 million data points from 9328 participants. All trials collected covariates and outcomes data at baseline and follow‐ups. The bespoke standardized repository is flexible to accommodate millions of data points without compromising data integrity. Data are easily retrieved for analysis using standard statistical programs.

Conclusions

The bespoke hybrid repository is complex to implement and to query but its flexibility in supporting datasets with varying sets of responses and outcomes with different data types is a worthy trade off. The large standardized LBP dataset is also an important resource useable by other LBP researchers.

Significance

A flexible adaptive database for pain studies that can easily be expanded for future researchers to map, transform and upload their data in a safe and secure environment. The data are standardized and harmonized which will facilitate future requests from other researchers for secondary analyses.

Improving the self-management of chronic pain: COping with persistent Pain, Effectiveness Research in Self-management (COPERS)

Background

Chronic musculoskeletal pain is a common problem that is difficult to treat. Self-management support interventions may help people to manage this condition better; however, there is limited evidence showing that they improve clinical outcomes. Our overarching research question was ‘Does a self-management support programme improve outcomes for people living with chronic musculoskeletal pain?’.

Aim

To develop, evaluate and test the clinical effectiveness and cost-effectiveness of a theoretically grounded self-management support intervention for people living with chronic musculoskeletal pain.

Methods

In phase 1 we carried out two systematic reviews to synthesise the evidence base for self-management course content and delivery styles likely to help those with chronic pain. We also considered the psychological theories that might underpin behaviour change and pain management principles. Informed by these data we developed the Coping with persistent Pain, Evaluation Research in Self-management (COPERS) intervention, a group intervention delivered over 3 days with a top-up session after 2 weeks. It was led by two trained facilitators: a health-care professional and a layperson with experience of chronic pain. To ensure that we measured the most appropriate outcomes we reviewed the literature on potential outcome domains and measures and consulted widely with patients, tutors and experts. In a feasibility study we demonstrated that we could deliver the COPERS intervention in English and, to increase the generalisability of our findings, also in Sylheti for the Bangladeshi community. In phase 2 we ran a randomised controlled trial to test the clinical effectiveness and cost-effectiveness of adding the COPERS intervention to a best usual care package (usual care plus a relaxation CD and a pain toolkit leaflet). We recruited adults with chronic musculoskeletal pain largely from primary care and musculoskeletal physiotherapy services in two localities: east London and Coventry/Warwickshire. We collected follow-up data at 12 weeks (self-efficacy only) and 6 and 12 months. Our primary outcome was pain-related disability (Chronic Pain Grade disability subscale) at 12 months. We also measured costs, health utility (European Quality of Life-5 Dimensions), anxiety, depression [Hospital Anxiety and Depression Scale (HADS)], coping, pain acceptance and social integration. Data on the use of NHS services by participants were extracted from NHS electronic records.

Results

We recruited 703 participants with a mean age of 60 years (range 19–94 years); 81% were white and 67% were female. Depression and anxiety symptoms were common, with mean HADS depression and anxiety scores of 7.4 [standard deviation (SD) 4.1] and 9.2 (SD 4.6), respectively. Intervention participants received 85% of the course content. At 12 months there was no difference between treatment groups in our primary outcome of pain-related disability [difference –1.0 intervention vs. control, 95% confidence interval (CI) –4.9 to 3.0]. However, self-efficacy, anxiety, depression, pain acceptance and social integration all improved more in the intervention group at 6 months. At 1 year these differences remained for depression (–0.7, 95% CI –1.2 to –0.2) and social integration (0.8, 95% CI, 0.4 to 1.2). The COPERS intervention had a high probability (87%) of being cost-effective compared with usual care at a threshold of £30,000 per quality-adjusted life-year.

Conclusions

Although the COPERS intervention did not affect our primary outcome of pain-related disability, it improved psychological well-being and is likely to be cost-effective according to current National Institute for Health and Care Excellence criteria. The COPERS intervention could be used as a substitute for less well-evidenced (and more expensive) pain self-management programmes. Effective interventions to improve hard outcomes in chronic pain patients, such as disability, are still needed.

Trial registration

Current Controlled Trials ISRCTN22714229.

Funding

The project was funded by the National Institute for Health Research Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 4, No. 14. See the NIHR Journals Library website for further project information.

Identifying back pain subgroups: developing and applying approaches using individual patient data collected within clinical trials

Background

There is good evidence that therapist-delivered interventions have modest beneficial effects for people with low back pain (LBP). Identification of subgroups of people with LBP who may benefit from these different treatment approaches is an important research priority.

Aim and objectives

To improve the clinical effectiveness and cost-effectiveness of LBP treatment by providing patients, their clinical advisors and health-service purchasers with better information about which participants are most likely to benefit from which treatment choices. Our objectives were to synthesise what is already known about the validity, reliability and predictive value of possible treatment moderators (patient factors that predict response to treatment) for therapist-delivered interventions; develop a repository of individual participant data from randomised controlled trials (RCTs) testing therapist-delivered interventions for LBP; determine which participant characteristics, if any, predict clinical response to different treatments for LBP; and determine which participant characteristics, if any, predict the most cost-effective treatments for LBP. Achieving these objectives required substantial methodological work, including the development and evaluation of some novel statistical approaches. This programme of work was not designed to analyse the main effect of interventions and no such interpretations should be made.

Methods

First, we reviewed the literature on treatment moderators and subgroups. We initially invited investigators of trials of therapist-delivered interventions for LBP with > 179 participants to share their data with us; some further smaller trials that were offered to us were also included. Using these trials we developed a repository of individual participant data of therapist-delivered interventions for LBP. Using this data set we sought to identify which participant characteristics, if any, predict response to different treatments (moderators) for clinical effectiveness and cost-effectiveness outcomes. We undertook an analysis of covariance to identify potential moderators to apply in our main analyses. Subsequently, we developed and applied three methods of subgroup identification: recursive partitioning (interaction trees and subgroup identification based on a differential effect search); adaptive risk group refinement; and an individual participant data indirect network meta-analysis (NWMA) to identify subgroups defined by multiple parameters.

Results

We included data from 19 RCTs with 9328 participants (mean age 49 years, 57% females). Our prespecified analyses using recursive partitioning and adaptive risk group refinement performed well and allowed us to identify some subgroups. The differences in the effect size in the different subgroups were typically small and unlikely to be clinically meaningful. Increasing baseline severity on the outcome of interest was the strongest driver of subgroup identification that we identified. Additionally, we explored the application of Bayesian indirect NWMA. This method produced varying probabilities that a particular treatment choice would be most likely to be effective for a specific patient profile.

Conclusions

These data lack clinical effectiveness or cost-effectiveness justification for the use of baseline characteristics in the development of subgroups for back pain. The methodological developments from this work have the potential to be applied in other clinical areas. The pooled repository database will serve as a valuable resource to the LBP research community.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme. This project benefited from facilities funded through Birmingham Science City Translational Medicine Clinical Research and Infrastructure Trials Platform, with support from Advantage West Midlands (AWM) and the Wolfson Foundation.

A systematic review reveals that the credibility of subgroup claims in low back pain trials was low

OBJECTIVES

To assess the credibility of subgroup claims in back pain randomized controlled trials.

STUDY DESIGN AND SETTING

A sample of reports of back pain trials from 2000 to 2015 that provided a subgroup claim were included (n=38). Two reviewers independently assessed risk of bias and credibility of subgroup claims as well as the strength of the author's claim. The credibility of subgroup claims was assessed using a 10-criteria tool, and strength of the subgroup claims was assessed based on seven criteria to categorize claims into a reasonably strong claim of a definitive subgroup effect or a more cautious claim of a possible effect.

RESULTS

A total of 91 claims of a subgroup effect were reported in the 38 included trials, of which 28 were considered strong claims of a definitive effect, and 63 were cautious claims of a possible effect. None of the subgroup claims met all 10 credibility criteria, and only 24% (22 claims) satisfied at least five criteria. The only criteria satisfied by more than 50% of the claims were if the subgroup variable was a characteristic measured at baseline, and whether the test of interaction was significant. All other criteria were satisfied by less than 30% of the claims. There was no association between the credibility of subgroup claims and the journal impact factor, risk of bias, sample size, or year of publication.

CONCLUSION

The credibility of subgroup claims in back pain trials is usually low, irrespective of the strength of the authors' claim.

Interpreting Effectiveness Evidence in Pain: Short Tour of Contemporary Issues

There is no shortage of treatment approaches offered to people with pain. The maze of options presents patients and clinicians with difficult choices. Key to making those choices is evidence of treatment effectiveness provided by clinical trials and systematic reviews. Recent growth in the number of clinical trials and systematic reviews, of both high and low quality, makes it vital that users of this evidence-clinicians, researchers, patients, and policy makers-have the skills and knowledge to critically interpret these studies. In this review, we discuss some contemporary issues regarding evidence of effectiveness derived from clinical trials and systematic reviews-issues that we think are critical to understanding the field. We focus on evidence of treatment effectiveness in pain, although many of these issues are relevant to and transferable across the spectrum of evidence-based practice.