Predicting response to a cognitive–behavioral approach to treating low back pain: Secondary analysis of the BeST data set

Abstract

Objective. Identifying factors that predict who is likely to gain the greatest benefit from different treatments for low back pain is an important research priority. Here we report moderator analyses of the Back Skills Training Trial (BeST) that tested a cognitive-behavioral approach for low back pain. Methods. We recruited 701 participants ages >18 years with at least moderately troublesome low back pain present for >6 weeks from 56 general practices in 7 localities across England to a trial adding a group cognitive-behavioral approach to active management advice. The cognitive-behavioral package had a moderate effect on primary outcomes (Roland Morris Disability Questionnaire [RMDQ] and modified Von Korff scales). At 12-month followup, we tested for interaction between randomized groups on 2 prespecified baseline variables (troublesomeness and fear avoidance) and 10 post hoc (exploratory) variables identified from previous studies. Results. Neither troublesomeness nor fear avoidance moderated treatment effect on any of our primary outcomes. In the final model, the only moderation by baseline variables of the effect of randomization was on the RMDQ outcome. Being younger and currently working both moderated treatment effect, resulting in larger improvements as a response to treatment. Conclusion. Although BeST is one of the larger trials of back pain treatment, it is still too small to reliably detect moderation if it exists. Since the significant moderation effects were only observed for 1 outcome measure in 3 of 10 post-hoc analyses, we cannot conclude that these are true moderation effects.

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

“…46 In this trial, females had comparatively greater improvement following group cognitive behavioural therapy compared to males. The treatment difference between male and female was -1.27…”

“… Three (8%) papers met all five criteria and therefore provided confirmatory evidence; Sheets 53 , Smeets 54 , & Underwood 46,58,59 . Two of these were too small to anticipate finding any important interaction if it were present (n = 148 & 259)…”

“…46,48,50 In BeST, younger participants gained more benefit from cognitive behavioural therapy than older participants on the RMDQ score. 46 The treatment difference was -1.58 (p = =0.035; 95% CI -3.05 to -0.12). As the p-value was <0.05, the interactions provided strong evidence.…”

“… Sometimes it was not clear from methods that subgroups analyses were going to be performed; they were just presented in the results 62,69,74,80  All papers measured subgroups of interest prior to randomisation, with most using adequate measurements 45,48,61, 72,75, 77  Four studies reported only the interaction effect sizes with confidence intervals 46,58,59, 82  Eight studies reported the p-values only 37,50,66,67,69, 83,86,88  Nine papers did not report either the interaction effect sizes or confidence intervals or p-values. 49, 60, 62-65, 68, 70, 71  Four studies reported subgroup analyses within individual subgroups rather than between group interaction.…”

“…In the Cherkin trial, the p-value was 0.10 while in the BeST trial, the treatment difference for the RMDQ score was -1.01 (p = 0.190; 95% CI -2.52 to 0.50) and -5.04 (p =1.184; 95% CI -12.47 to 2.40) for MVK pain score. 46,48 27 …”