Objectives: A nationwide survey was conducted to clarify the epidemiological features of patients with chronic pancreatitis (CP) in Japan. Methods: In the first survey, both the prevalence and the incidence of CP in 2011 were estimated. In the second survey, the clinicoepidemiological features of the patients were clarified by mailed questionnaires. Patients were diagnosed by the Japanese diagnostic criteria for chronic pancreatitis 2009. Results: The estimated annual prevalence and incidence of CP in 2011 were 52.4/100,000 and 14.0/100,000, respectively. The sex ratio (male/female) of patients was 4.6, with a mean age of 62.3 years. Alcoholic (67.5%) was the most common and idiopathic (20.0%) was the second most common cause of CP. Comorbidity with diabetes mellitus (DM) and pancreatic calcifications (PC) occurred more frequent in ever smokers independently of their drinking status. Among patients without drinking habit, the incidences of DM and PC were significantly higher in ever smokers than in never smokers. The multiple logistic regression analysis revealed smoking was an independent factor of DM and PC in CP patients: DM, Odds ratio (OR) 1.644, 95% confidence interval (CI) 1.202 to 2.247 (P = 0.002): PC, OR 2.010, 95% CI 1.458 to 2.773 (P < 0.001). On the other hand, smoking was not identified as an independent factor for the appearance of abdominal pain by this analysis. Conclusion: The prevalence of Japanese patients with CP has been increasing. Smoking was identified as an independent factor related to DM and PC in Japanese CP patients.
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