[Clinical features and risk factors for early relapse of pediatric ulcerative colitis]

Objective: To investigate the clinical features of pediatric ulcerative colitis (UC) and analyze the risk factors of disease relapse. Methods: The clinical data of 79 children with UC diagnosed in Beijing Children's Hospital, Capital Medical University from January 2016 to February 2021 were retrospectively analyzed. They were divided into early relapse group and non-early relapse group according to the clinical relapse within 12 months after diagnosis. T-test, rank sum test, χ² test or Fisher's exact test were used to compare the variables between the 2 groups, including the clinical features, laboratory examination results and treatments. The Logistic regression was used to analyze the risk factors of early relapse. The cumulative relapse rate during follow-up was calculated by Kaplan-Meier method. Results: Among the 79 UC children, 46 were males and 33 were females, and the age of onset was 10.6 (6.4, 12.7) years. The children were mainly characterized by extensive disease (E3) and pancolitis (E4) (51/79, 65%), moderate to severe activity (48/79, 61%) and moderate to severe inflammation of colonic mucosa (71/79, 90%). Thirty-eight (48%) patients had atypical phenotype and 17 (22%) had extraintestinal manifestations. The follow-up period was 43.9 (22.8, 61.3) months, and of the 41 patients rechecked with colonoscopy, 7 (17%) had disease progression. According to Kaplan-Meier analysis, the cumulative relapse rate of the 79 cases at 3 months, 6 months, 1 year and 2 years after diagnosis were 27% (21/79), 47% (37/79), 57% (45/79) and 73% (53/73), respectively. There were 45 children (57%) in early relapse group and 34 (43%) in non-early relapse group. In early relapse group, hemoglobin and mucosal healing rate were both significantly lower (105 (87, 122) vs. 120 (104, 131) g/L, 28% (7/25) vs. 7/9, Z=-2.38, χ²=4.87, both P<0.05). The rate of steroid-dependent, E3 and step-up therapy during the induction period were all significantly higher than those in non-early relapse group (11/19 vs. 1/12, 24% (11/45) vs. 6% (2/34), 29% (13/45) vs. 6% (2/34), χ²=5.67, 4.85, 6.66, all P<0.05). Multivariate Logistic regression analysis showed that extraintestinal manifestations (OR=4.33, 95%CI 1.05-17.83), E3 (OR=8.27, 95%CI 1.47-46.46) and step-up therapy during the induction period (OR=5.58, 95%CI 1.01-30.77) were independent risk factors for early relapse. Conclusions: Pediatric UC is usually extensive and severe, with atypical phenotype, a high rate of relapse and a risk of disease progression. Extraintestinal manifestations, E3 and step-up therapy during the induction period are independent risk factors for early relapse.