Head-to-head trials in inflammatory bowel disease: past, present and future.

With the increase in the number of novel drugs for inflammatory bowel disease (IBD), comparing therapeutic options or strategies has become a key challenge in IBD trials. Head-to-head trials designed and powered to enable formal comparisons are the gold standard in comparative research. Indeed, these trials are requested by some health authorities for evaluating the positioning of new treatments in IBD, as well as helping prescribing physicians to select the most appropriate treatment options for their patients. Despite head-to-head trials including aminosalicylate therapy in IBD having been performed decades ago, the first results of a randomized controlled trial directly comparing biologic agents with different modes of action have only now been published, mainly owing to important methodological issues. This Perspective provides an overview of the past, current and future concepts in IBD trial design, with a detailed focus on the role of comparative research and the challenges and pitfalls in undertaking and interpreting the results from such studies.