Clinical Characteristics and North-South Differences of Inflammatory Bowel Disease in China: A Cross-Sectional Study and Meta-Analysis

Objective This study aimed to estimate the incidence rate and clinical characteristics of inflammatory bowel disease (IBD) in the Chinese population, specially comparing the North and South regions. Methods We designed a questionnaire survey for patients diagnosed with IBD and conducted a systematic literature search in PubMed, China National Knowledge Internet, and Wanfang digital database, covering studies published between 2012 and 2022. Meta-analysis was performed to determine the overall incidence rate and prevalence of clinical manifestations of Crohn's disease (CD) and ulcerative colitis (UC) in mainland China. Clinical phenotypes and demographic characteristics were calculated with 95% confidence intervals (CI). A comparison between the northern and southern regions was also conducted. Results The questionnaire survey included 440 patients, and 64 publications were included for Meta-analysis. The overall incidence rates of IBD, CD, and UC were 1.36 (95% CI: 0.79-2.33) per 100,000 person-years, 0.23 (95% CI: 0.09-0.58) per 100,000 person-years, and 1.12 (95% CI: 0.69-1.80) per 100,000 person-years, respectively. The incidence rates of IBD, CD, and UC were all higher in southern China compared to the North. Clinical characteristics of 440 IBD patients from the questionnaire and 2,821 CD patients and 12,809 UC patients from the literature were analyzed. There were more male patients compared to female patients. CD cases in the North exhibited earlier disease diagnosis (P < 0.01), more upper gastrointestinal lesions (P < 0.01), and higher hospitalizations rates (P < 0.01) compared to the South. UC cases in the North had higher severity (P < 0.01), anemia rates (P < 0.01), and weight loss (P < 0.01) compared to the South. Conclusions The incidence rates of IBD, CD, and UC were higher in southern China than in the North. Northern patients exhibited more severe symptoms compared to their southern counterparts.