Endpoints for Perianal Crohn's Disease Trials: Past, Present and Future

Since the 1980s, many studies have evaluated the efficacy of therapies to improve the outcomes of patients with perianal Crohn's disease. We performed a systematic review to describe the evolution of endpoints in perianal fistulizing Crohn's disease. Efficacy outcomes, definitions and measurement tools were assessed.

Electronic databases were searched up to November 1, 2020. All published randomized placebo-controlled trials enrolling patients with perianal fistula and Crohn's disease were eligible for inclusion. Ongoing randomized clinical trials were also described.

Nineteen randomized controlled trials were included. Clinical efficacy endpoints were reported in all trials. Clinical response was the most frequent primary endpoint [6/19 studies, 31.6%], followed by clinical remission in four studies [21%]. Clinical response was defined as closure of at least 50% of fistulas, while remission was defined as closure of all fistulas. A combined clinical and radiological primary endpoint was used to assess fistula healing in four studies [21%]. The Perianal Disease Activity Index was a primary endpoint in only one study [5.5%]. In addition, eight ongoing controlled trials were identified. Combined clinical and radiological remission was the most frequent primary endpoint in these studies [4/8, 50%].

In this systematic review, significant changes in outcomes used in randomized clinical trials of perianal Crohn's disease were observed. Radiological endpoints are increasingly used in perianal fistulizing Crohn's disease trials.