Optimising clinical trial design choices in inflammatory bowel disease.

The success of inflammatory bowel disease (IBD) clinical trials is strongly influenced by study design and disease-specific operational challenges. Over the past decade, however, IBD clinical trials face slow enrolment, poor retention, accumulating costs and limited representativeness. Trials are further constrained by protocol and operational complexity, financial pressures and regulatory requirements. Carefully selected and optimised trial designs may address the inherent challenges of IBD research and should take into account the patient profiles under investigation, mode of action and speed of onset of effect of the investigational product, among other factors. This narrative review discusses four key study design strategies for IBD clinical trials, including treat-through maintenance, responder re-randomisation, Master Protocol approaches (basket, umbrella and platform trials) and Bayesian methodologies. Treat-through maintenance designs are effective at evaluating sustained efficacy and real-world durability, whereas responder re-randomisation approaches are widely used in drug registration programmes to distinguish induction and maintenance effects for regulator clarity. Master Protocol designs may improve efficiency and reduce placebo exposure, while trials using Bayesian methodologies can strengthen interpretation of efficacy and safety outcomes, particularly in early-phase or complex studies. Key considerations within protocols include the use of co-primary endpoints, selection of secondary/exploratory endpoints, control group design and integrating digital health technologies, among others. Strategic application of innovative methodologies can improve trial delivery and enhance data robustness and interpretability, thus supporting more efficient development of effective therapies for patients with IBD.