The interpretation of clinical relevance in randomised clinical trials in patients with chronic low back pain: protocol for a meta-research study.

Chronic low back pain (cLBP) is one of the leading worldwide causes of disability. The smallest worthwhile effect (SWE) parameter has been proposed to find a threshold of clinical relevance. Specific values of the SWE have been calculated in patients with cLBP for pain intensity, physical functioning and time to recovery for physiotherapy compared with no intervention. Our objectives are 1) To evaluate how authors have interpreted the clinical relevance of the effect of physiotherapy compared to no-intervention on pain, physical functioning and time to recovery; 2) To reinterpret the clinical relevance of these between-group differences based on the available SWE estimates; 3) To evaluate, for descriptive purposes, whether the studies are adequately powered or underpowered considering the published SWE values and a power threshold of 80%. A systematic search in Medline, PEDro, Embase and Cochrane CENTRAL will be conducted. We will search for RCT investigating the effectiveness of physiotherapy as compared to no interventions in people with cLBP. We will compare the authors' interpretation of results for clinical relevance with their results to determine if they meet their a-priori definitions. Then, we will perform a re-interpretation of the between-group differences based on SWE values published for cLBP.