The Incidence of Proximal Extension of Ulcerative Proctitis in Japan and Factors Related to Proximal Extension

抄録

The incidence of proximal extension in patients with ulcerative proctitis is reported to be 18%-46%, but recent data on the incidence in Japan is inadequate. The aim of this study was to investigate the incidence of proximal extension of ulcerative proctitis and factors associated with the extension in Japan. This is a retrospective observational study involving a cohort of 53 patients with an initial diagnosis of ulcerative proctitis. Following verification of the diagnoses, demographic and clinical data were compiled. The cumulative incidence of proximal extension was estimated as ‘person-years’ and cumulative probability was calculated by the Kaplan-Meyer method. Univariate and multivariate analyses were performed to identify association factors. During a mean follow-up of 6.8 years, proximal extension was observed in 14 patients (26.4%). The cumulative incidence of proximal extension was 4.22/100 person-years and the cumulative probability at 5 years was 20.1%, consistent with recent reports from Western countries and data obtained in Japan over 2 decades ago. Univariate analysis showed active smoking (P = 0.025) and corticosteroid therapy (P = 0.006) to be risk factors in proximal extension, however multivariate analysis revealed that corticosteroid therapy was the only significant factor (P = 0.005) separating patients with and without proximal extension. No patient underwent colectomy. The incidence of proximal extension in ulcerative proctitis in Japan is comparable to that in Western countries and has not changed significantly over the past two decades. Corticosteroid therapy was identified as the only significant factor in proximal extension.