A recently published meta-epidemiological study has evaluated if allocation concealment and intention-to-treat analysis influence the size of treatment effects of randomised controlled trials evaluating physiotherapy interventions for people with low back pain. Five databases (PubMed, Embase, Cochrane Database of Systematic Reviews, PEDro, CINAHL) were searched to identify low back pain trials that compared physiotherapy intervention to placebo, no intervention or minimal intervention and used pain and/or disability as outcomes. For each included trial the PEDro ratings for allocation concealment and intention-to-treat analysis were downloaded from PEDro and the pain and/or disability outcomes were extracted and converted to a 0-100 scale. A meta-regression was performed to evaluate the influence of concealed allocation and intention-to-treat analysis on treatment effect size. The analysis included 128 trials – 45% of the trials achieved allocation concealment and 32% performed intention-to-treat analysis. There was no influence of allocation concealment on treatment effects for pain (regression coefficient 0.009; 95% confidence interval (CI) -2.91 to 2.91) and disability (regression coefficient 1.13; 95% CI -1.35 to 3.62). There was also no influence of intention-to-treat analysis on treatment effects for pain (regression coefficient 1.38; 95% CI -1.73 to 4.50) or disability (regression coefficient 1.27; 95% CI -1.39 to 3.64). These results are consistent with previous research that investigated the impact of allocation concealment or intention-to-treat analysis on treatment effect estimates for continuous outcomes.
de Almeida MO, et al. Allocation concealment and intention-to-treat analysis do not influence the treatment effects of physiotherapy interventions in low back pain trials: a meta-epidemiologic study. Arch Phys Med Rehabil 2019;100(7):1359-66