The evolving landscape of chronic pancreatitis in Japan: findings from a nationwide epidemiological survey in 2021.

BACKGROUND: To reassess the clinico-epidemiological characteristics of chronic pancreatitis (CP) in Japan, we conducted a nationwide epidemiological survey. METHODS: A two-stage nationwide survey was performed targeting patients with CP treated at participating hospitals in 2021. The first-stage survey estimated the number of patients, and the second-stage survey collected detailed clinical information. RESULTS: The estimated number of patients with definite or probable CP in 2021 was 73,590 (prevalence, 58.6 per 100,000 population), representing a 30% increase from 2016. The estimated number of newly diagnosed patients was 17,490, corresponding to an annual incidence of 13.9 per 100,000 population. Detailed clinical data were available for 4633 patients. The male-to-female ratio was 4.15:1, the mean age in 2021 was 64.4 years, and the mean age at diagnosis was 58.7 years. Alcohol was the leading etiology (69.6%), followed by idiopathic CP (24.3%). Notably, alcohol-related CP accounted for 39.5% of female cases. Diabetes mellitus and pancreatic exocrine insufficiency were present in 45.8% and 36.6% of patients, respectively. Endoscopic treatment was the initial intervention in 92.8% of patients undergoing treatment for pancreatic stones and/or pancreatic duct strictures. Malignancies were identified up to the time of the survey in 18.0% of patients, including pancreatic cancer in 89 patients. CONCLUSIONS: The prevalence of CP in Japan continues to increase. The aging CP population, the increasing proportion of alcohol-related CP among women, and the substantial burden of diabetes, exocrine insufficiency, and malignancy underscore the growing healthcare impact of CP and the need for effective prevention and long-term management strategies.