Total word count including appendix: 93,499 ii
ABSTRACT BackgroundThere 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 objectivesOverall aim was to improve the clinical 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 To achieve 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 main effect of interventions and no such interpretations should be made.iii
MethodsFirstly, 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 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 dataset we sought to identify which participant characteristics, if any, predict response to different treatments (moderators) for clinical and cost effectiveness outcomes.We did an ANCOVA 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 to identify sub-groups defined by multiple parameters.
ResultsWe included data from 19 randomised controlled trials with 9,328 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 sub-group identification that we identified. Additionally we explored the application of Bayesian indirect network metaanalysis. This method produced varying probabilities that a particular treatment choice would be most likely to be effective for a specific patient profile.
ConclusionThese data lack clinical 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.iv The pooled repository database will serve as a valuable resource to the LBP research community.
FundingFunding from the NIHR Programme Grants for Ap...