Abstract
BACKGROUND: Eligibility criteria in clinical trials have been criticised for being overly restrictive without clinical justification. OBJECTIVE: We aimed to investigate the types, evolution, and current status of eligibility criteria in clinical trials for inflammatory bowel diseases (IBD). METHODS: We performed a clinical trial databank search on clinicaltrials.gov, and included all Phase 3 placebo-controlled randomised-controlled trials (RCTs) investigating biologics or small molecules as induction therapy for moderate-to-severe Crohn's disease (CD) and ulcerative colitis (UC). Eligibility criteria were analysed both quantitatively and qualitatively. RESULTS: Fifty-nine RCTs were identified between the year 2000 and 2022 (30 for CD and 29 for UC). The median (interquartile range) number of eligibility criteria was 44 (38-49), and did not significantly change over the studied time period (p = 0.26). Qualitative analysis showed that common patient populations, such as older patients, therapy refractory patients, patients with comorbidities, prior malignancies, unclassified IBD type, ulcerative proctitis, stricturing and fistulizing CD, as well as patients with an ostomy, were often excluded. Heterogeneity in eligibility criteria across the different IBD clinical trials was found, such as for disease activity measurement, dosage of concomitant medication, wash-out period of advanced therapies, and laboratory tests. CONCLUSION: The median number of eligibility criteria for IBD RCTs did not significantly change over time. The eligibility criteria are however restrictive and complex, limiting the generalisability of efficacy and safety outcomes in daily practice when drugs are approved. Future research is needed to investigate the impact of broadening eligibility criteria to better encompass real-world practice.