Methodological limitations prevent definitive conclusions on the effects of patients' preferences in randomized clinical trials evaluating musculoskeletal conditions

Objective: To systematically and critically evaluate how patients' preferences have been measured and analyzed in randomized clinical trials (RCTs) evaluating musculoskeletal conditions. Study Design and Settings: PsycINFO, MEDLINE, EMBASE, Cochrane Central Register of Clinical Trials, CINAHL, LILACS, and PEDro were searched for RCTs in which authors reported that patients' preferences were measured before randomization. Results: Five studies investigated if patients' preferences modify treatment effect (difference in outcomes between allocation groups), and seven studies examined the effect of patients' preferences on outcomes (within-group changes in outcome over time). Three studies provided data to be used in a statistical model based on tests of interactions. Statistical significance of the effect of preferences on treatment outcomes was not found. Included studies were not powered for tests of interaction, and only two (17%) studies described a preplanned analysis for treatment preference. Four (33%) trials did not show evidence of selective reporting bias. Additionally, authors used heterogeneous methods to measure patients' preferences. Conclusion: Methodological limitations of the available evidence suggest that it might be early to conclude whether patients' preferences influence the findings of RCTs evaluating musculoskeletal conditions. Future studies should use standardized methods to measure patients' preferences and then individual studies can be pooled in a meta-analysis.