Challenges in conducting an individual participant data meta-analysis of non-steroidal anti-inflammatory drugs for patients with (sub)acute low back pain: a systematic review and report on data availability

OBJECTIVE: We planned to conduct an individual participant data meta-analysis (IPD-MA) to investigate the efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) compared with placebo in patients with (sub)acute low back pain (LBP). This report describes the challenges encountered in conducting this IPD-MA and their implications. DESIGN: A systematic review. DATA SOURCES: Medline ALL, Embase and the Cochrane Central Register of Controlled Trials were searched through January 2024. ELIGIBILITY CRITERIA: We included randomised clinical trials (RCTs) from the Cochrane review on NSAIDs for (sub)acute LBP and trials identified through the aforementioned data sources. We compared NSAIDs (regardless of administration route) to placebo on effectiveness outcomes. Our primary outcomes were pain intensity, physical functioning and health-related quality of life at 1-, 3- and 12-week follow-ups, with secondary outcomes including adverse events. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers screened and included eligible studies. Risk of bias (RoB) was assessed using the Cochrane RoB tool 2. Original authors of included RCTs were contacted based on a hierarchy: Corresponding > First > Last > Other authors via email, social media or institution. For contributors, we requested their study protocol, codebook and IPD, and provided our data-sharing agreement and transfer protocol. One-stage IPD-MA was planned with a generalised linear mixed model. RESULTS: We identified 10 RCTs. Seven authors responded, but only one author agreed to share IPD. Data were unavailable or lost due to the age of the trials, dissolution of research departments, lack of records by sponsoring companies, market withdrawal of the studied drug, or contractual restrictions on data sharing. Two RCTs had a 'low' overall RoB, four had 'some concerns' and four had 'high'. With only one IPD set obtained, the planned IPD-MA could not be conducted. CONCLUSIONS: This IPD-MA on NSAIDs for (sub)acute LBP could not be completed due to challenges in data acquisition. In future IPD research, researchers should focus on clearer rationale, recent RCTs, improved data-sharing and storing practices.