Moderators of treatment effect of non-steroidal anti-inflammatory drugs for patients with (sub) acute low back pain: Protocol for a systematic review with individual participant data meta-analysis

A Cochrane review found that non-steroidal anti-inflammatory drugs (NSAIDs) are slightly more effective than placebo on acute and subacute low back pain (LBP) outcomes (pain intensity, disability, and global improvement). Our objectives are: (1) to assess the overall treatment effect of NSAIDs in adults with acute and subacute LBP; (2) to identify the moderation of baseline patients’ characteristics on treatment effect. We will conduct a systematic search of RCTs on effectiveness of NSAIDs compared with placebo in adults with non-chronic LBP in Medline ALL, Embase, Cochrane Central Register of Controlled Trials*. We will screen the records after January 2020, and include eligible RCTs before January 2020 screened by the Cochrane review mentioned above. Our primary outcomes are pain intensity, disability, and health-related quality of life, secondary outcomes are adverse events. Our IPD dataset will consist of the information on each eligible trial characteristics and included variables according to a predefined coding scheme. We will assess risk-of-bias of included RCTs with the Cochrane Risk Of Bias (RoB)-2 assessment tool. We will perform power calculations with closed-form solutions and prioritize a one-stage approach for IPD-MA. For reporting the results, we will adhere to the PRISMA-IPD statement.