Changes in the clinical course and prognosis of ulcerative colitis in Chinese populations: a retrospective cohort study.

Background/aims: Data on the natural course of Chinese patients with ulcerative colitis (UC) was lacking. This study aimed to evaluate the natural history and prognosis of patients with UC in the past 15 years in China.

Methods: This cohort study included patients with UC in a tertiary hospital in southern China from 2007 to 2021 (cohort I: 2007-2011, cohort II: 2012-2016, cohort III: 2017-2021). Patients' clinical characteristics and natural history were analyzed retrospectively.

Results: Of 1,139 included patients, 683 patients presented with proctitis or left-sided colitis at diagnosis and 38.5% of them (263/683) developed proximal disease extension. Fifty-eight percent of patients experienced relapse, chronic continuous and intermittent active course. Five patients (0.4%) developed colorectal tumors/dysplasia. The overall surgery rate was 8.6%, and the rates were 14.2%, 7.8%, and 8.0% in the 3 cohorts, respectively (P= 0.059). Average time from diagnosis to surgery decreased from cohorts I to III (144 months vs. 36 months, P< 0.001), so did the use of glucocorticoids (58.2% vs. 43.5%, P< 0.001) and immunosuppressants (14.1% vs. 13.4%, P= 0.016), and days of hospitalization (13 days vs. 9 days, P< 0.001). Biologics were used more frequently during the first year (0.8%, 2.1%, and 13.7% for cohorts I to III, respectively; P< 0.001). The rate of mucosal healing increased over time.

Conclusions: In Chinese UC patients, one-third of patients experienced proximal disease extension. The rates of malignancy and mortality were low. More biologics were used, while use of immunosuppressants and glucocorticoids were reduced over time. Early biologics use seemed to promote mucosal healing, but the rate of colectomy has not dramatically decreased.