RESUMEN
BACKGROUND: The use of biologics to treat inflammatory bowel disease is supported by robust randomized controlled trials in both ulcerative colitis and Crohn's disease. Nonetheless, an understanding of the principles of clinical trial design is necessary to extrapolate study findings to clinical practice. METHODS: We conducted a review of inflammatory bowel disease registrational clinical trials of biologics to determine how differences in trial design potentially influence results and interpretation. RESULTS: Registrational trials of biological agents have used diverse patient populations, outcome measures, and designs, which makes comparisons of results among studies difficult. Key differences among trials include patient populations, choice of symptom-based measures or objective outcomes as endpoints, and overall trial design. Additional factors, including analytical methods, can also influence the interpretation of outcomes. CONCLUSIONS: The most robust evidence is derived from comparative effectiveness trials. In the absence of these, clinicians should be aware of the various methodological issues which could impact interpretation of efficacy and safety outcomes, including differences in patient population, study design, and analytic methodology.