The burden and unique patterns of extraintestinal manifestations in Chinese inflammatory bowel disease: a nationwide multicenter investigation

Extraintestinal manifestations (EIMs) are a significant disease burden in inflammatory bowel disease (IBD). However, large-scale epidemiological data from the Chinese population remain scarce. This nationwide, multicenter, retrospective cross-sectional study included 2,252 adult IBD inpatients from 10 clinical centers. Data on demographics, clinical features, and EIMs were collected and analyzed using descriptive statistics and logistic regression. Of the 2252 patients, 384 (17.1%) reported at least one EIM. Among these, data on temporal sequence were available for 310 patients, of whom 70 (22.6%) developed their first EIM before the onset of intestinal symptoms. The overall prevalence of EIMs was significantly higher in Crohn's disease (CD) than in ulcerative colitis (UC) (20.5% vs. 15.4%, P = 0.003). Joint manifestations (10.0%) and aphthous ulcers (5.5%) were most common, with aphthous ulcers significantly more frequent in CD (11.2% vs. 2.8%, P < 0.001). The prevalence of classic EIMs such as arthritis/arthralgia (8.0%), uveitis (0.5%), and erythema nodosum (0.9%) fell within the low-to-mid range of global reports. Significant co-occurrence was observed among EIMs. For example, arthritis/arthralgia showed strong associations with uveitis (OR = 31.88) and erythema nodosum (OR = 13.34). Analysis of medication history revealed higher use of infliximab in patients with arthritis/arthralgia (47.0%) and pyoderma gangrenosum (71.4%), and frequent glucocorticoid use in those with venous thromboembolism (72.4%). In this inpatient-based cohort, the lower prevalence of classic EIMs in Chinese IBD patients may reflect clinical underdetection or genuine epidemiological differences. EIMs can precede intestinal symptoms and influence each other, underscoring the need for proactive, systematic assessment in clinical practice.