Proven treatments for low back pain 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 healthcare resources. This systematic review aimed to understand which people with low back pain are most likely to benefit from different treatment approaches (active physical treatments, passive physical treatments, and psychological treatments).
Sensitive searches were performed in four databases, including Medline. Randomised controlled trials that had interventions delivered by a therapist and a sample size >179 were included. Since this was an individual patient data meta-analysis, authors of trials were invited to share data with the research team. Interventions were categorised as: control (non-active usual care), sham control (sham acupuncture, electrotherapy, advice/education, mock transcutaneous electrical nerve stimulation), active physical (exercise and graded activity), passive physical (individual physiotherapy, manual therapy, acupuncture) and psychological (advice/education, psychological therapy). Follow-up was classified as: short- (2 and 3 months), mid- (6 months) and long-term (12 months post randomisation). Thirty-two outcomes were classified into physical disability, pain, psychological distress and non-utility quality of life domains.
Pooled analyses were performed on individual patient data from at least two trials so as not to replicate original analyses. Missing data was not imputed. Potential moderators were identified from a previous systematic review on treatment moderators (ie, factors measured pre-randomisation indicating who benefits most and least from a treatment) and by including individual patient data from all trials in a single mixed-effects meta-analysis model for each follow-up time (with moderators declared statistically significant (p<0.05) or weakly significant (p<0.20)). Two approaches were used to identify sub-groups: Recursive Partitioning and Adaptive Refinement by Directed Peeling. Both aim to identify subgroups of participants who experience treatment effects larger than other participants.
19 trials (n=9,328 participants) were included in the analyses. The average age of participants was 49 years, 57% were female and the average Roland Morris Disability Questionnaire score at baseline was 10 out of 24 points (14 trials). Three treatment types were chosen for the exploration of potential moderators: active physical treatments, passive physical treatments, and psychological treatments. Control arms included non-active usual care and sham interventions. Age, gender, low back pain disability and severity, and psychological state were at least weakly significant in one or more of the moderator analyses and were considered for further subgroup analysis.
Participants with greater psychological distress and physical disability had the greatest improvement on the Mental Component Scale of Short Form Health Survey (12 or 36 item) from passive physical treatment compared to non-active usual care (treatment effects 4.3; 95% confidence interval (CI) 3.4 to 5.2). Recursive partitioning method found that participants with worse disability at baseline had the greatest reductions in disability measured using the Roland Morris Disability Questionnaire from psychological treatment compared to non-active usual care (treatment effects 1.7; 95% CI 1.1 to 2.3). Adaptive risk group refinement did not find any subgroup that would experience a larger benefit from psychological treatment over non-active usual care. Neither statistical method identified any subgroups that would experience a larger benefit from active physical treatment over non-active usual care.
Passive physical treatments for low back pain 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. Active physical treatments appeared to help all subgroups equally. However, the size of the additional benefit achieved in the subgroups was small and unlikely to be clinically important. These findings do not support the use of sub-grouping for people with low back pain.
Hee SW, et al. 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. BMC Musculoskelet Disord 2021;22(191):Epub.