In trials of physiotherapy for chronic low back pain, clinical relevance is rarely interpreted, with great heterogeneity in the frameworks and thresholds used: a meta-research study.

QUESTIONS: How do authors of randomised controlled trials (RCTs) interpret the clinical relevance of the effects of physiotherapy interventions compared with no intervention on pain intensity, physical function and time to recovery in people with chronic low back pain (CLBP)? How can the clinical relevance be re-interpreted based on the available smallest worthwhile effect (SWE) threshold for this comparison? Are the studies in this field adequately powered? DESIGN: Cross-sectional meta-research study. PARTICIPANTS: People with CLBP. OUTCOME MEASURES: Pain intensity, physical function and time to recovery. RESULTS: This review included 23 RCTs with 1,645 participants. Twenty-two and 18 studies were included in the analysis of pain intensity and physical function, respectively. No studies investigated time to recovery. Sixteen studies reported varying thresholds to interpret clinical relevance for physical function and pain intensity. Discrepancies between interpretation using the minimal important difference and SWE values were observed in five studies. Study power ranged from 9% to 98%, with only four studies having a power > 80%. CONCLUSION: Little attention is given to the interpretation of clinical relevance in RCTs comparing physiotherapy with no intervention in CLBP, with great heterogeneity in the frameworks and thresholds used. Future trials should inform patients and clinicians on whether the effect of an intervention is large enough to be worthwhile, using a reliable and comprehensive approach like available SWE estimates. REGISTRATION: medRxiv https://doi.org/10.1101/2022.12.14.22283454.

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.