Abstract
BACKGROUND: Irritable bowel syndrome (IBS) is one of the most common gut-brain interaction disorders. Most current IBS randomized controlled trials (RCTs) do not justify their choice of outcomes, and inappropriate outcome selection may obscure efficacy evaluation. OBJECTIVE: In this study, we systematically organize outcome-related information from IBS RCTs, encompassing two key components: categorizing outcomes into distinct domains, and summarizing the corresponding outcome measurement instruments for each domain. We also classify these outcome measures based on drug therapeutic mechanisms, IBS subtypes, and the research aims of RCTs, providing a reference basis for the comprehensive and accurate selection of outcome measures for IBS RCTs. SEARCH STRATEGY: We developed a systematic search (PubMed, Embase, Cochrane Library; up to May 2023) with an information specialist, combining "IBS" and "RCT" concepts. Outcomes and their instruments were categorized into domains, stratified by IBS subtype and intervention. RESULT: From 408 included studies, outcomes fell into four main domains: global improvement (76.96%), individual symptoms (64.46%), quality of life (43.63%), and psychological status (24.26%). Key instruments included IBS-SSS (global improvement), BSFS (stool consistency), IBS-QOL (quality of life), and HADS (psychological status). IBS-C emphasized defecatory straining, while IBS-D focused on defecatory urgency. Most psychological therapy uses VSI for psychological assessment. Gut-directed drug trials are rarely used for evaluation in the psychological domain. Only 3 of 146 long-term efficacy studies included recurrence rates. CONCLUSION: Selecting appropriate outcome measures based on drug mechanisms, different IBS subtypes, and the specific research objectives of RCTs can allow for accurate efficacy evaluation. However, the placebo effect and long-term effect evaluation require more attention.