Natural history of acute pancreatitis: a long-term population-based study.

Objectives: It is unknown whether after an initial attack of acute pancreatitis, the inflamed gland heals completely, or whether and under what circumstances the disease progresses to chronic pancreatitis. Therefore, the aim of this study was to investigate the progression of disease from acute to chronic pancreatitis.

Methods: During a 20-year period, 532 patients who were hospitalized after an initial attack of acute pancreatitis were followed up for an average of 7.8 years (range: 1 day to 19.7 years). We used the Kaplan-Meier method to study the frequency of recurrent attacks of pancreatitis, subsequent development of chronic pancreatitis, and all-cause mortality during the follow-up period in patients with pancreatitis due to different causes.

Results: During the follow-up period, recurrent pancreatitis developed in 88 (16.5%) patients. The annual relapse rates were 5.3, 1.5, 0.6, and 1.9/100 per year in patients with acute pancreatitis due to alcohol, gallstones (biliary), and other identified causes of unknown origin (idiopathic), respectively. Chronic pancreatitis developed only in alcoholics, independent of the severity of the first attack and also of discontinuation of alcohol and nicotine consumption. The cumulative incidence of chronic pancreatitis was 13% in 10 years and 16% in 20 years. After surviving a second attack, the incidence of chronic pancreatitis increased distinctly to 38% after only 2 years of follow-up. Smoking significantly enhanced the risk of progression from acute to chronic alcoholic pancreatitis.

Conclusions: The progression from acute to chronic pancreatitis occurred only in alcoholics. In this group, a substantial number of patients developed chronic pancreatitis in a short period of time after surviving a second attack of acute pancreatitis. Both alcohol consumption and smoking at this time are risk factors for the transition from acute to chronic pancreatitis.