Personalized (N-of-1) Clinical Trials for Inflammatory Bowel Disease: Opportunities and Challenges.

Background & aims: Heterogeneity of treatment effects in inflammatory bowel disease (IBD) means that many individuals or patient subgroups depart from the average for whom the outcomes from traditional randomized trials may not be applicable. The N-of-1 trial is a design in which a single patient is followed over time with the treatments being randomized from period to period with the intention of finding the most effective treatment for that patient. The aim was to investigate the utility of N-of-1 trials in IBD.

Methods: To identify relevant articles for this scoping review, a MEDLINE literature search was conducted through the PubMed platform for articles published in the English language using the search terms "inflammatory bowel disease," "Crohn's disease," "ulcerative colitis," "N-of-1 trials," "single case designs," and "personalized trials."

Results: N-of-1 trials have seen a resurgence across several medical disciplines, driven by a need for more personalized medicine and patient-centered health care; their use in IBD is scarce with only 3 trials identified. Studies involving multiple N-of-1 trials can generate robust evidence for each participant and average effect estimates. The N-of-1 trial may hold potential for studying patients with IBD that are excluded from or underrepresented by randomized trials, such as those with extraintestinal manifestations, pouchitis, and proctitis. Although methodologically sound and akin to the rigor of a randomized controlled trial, the crossover periods inherent to the study design can be perceived as burdensome by patients and researchers.

Conclusions: The N-of-1 trial design provides a patient-centered means of objectively determining individual response to therapy.