Acute pancreatitis precedes chronic pancreatitis in the majority of patients: Results from the NAPS2 consortium

Introduction: The mechanistic definition of chronic pancreatitis (CP) identifies acute pancreatitis (AP) as a precursor stage. We hypothesized that clinical AP frequently precedes the diagnosis of CP and is associated with patient- and disease-related factors. We describe the prevalence, temporal relationship and associations of AP in a well-defined North American cohort. Methods: We evaluated data from 883 patients with CP prospectively enrolled in the North American Pancreatitis Studies across 27 US centers between 2000 and 2014. We determined how often patients had one or more episodes of AP and its occurrence in relationship to the diagnosis of CP. We used multivariable logistic regression to determine associations for prior AP. Results: There were 624/883 (70.7%) patients with prior AP, among whom 161 (25.8%) had AP within 2 years, 115 (18.4%) within 3-5 years, and 348 (55.8%) >5 years prior to CP diagnosis. Among 504 AP patients with available information, 436 (86.5%) had >1 episode. On multivariable analyses, factors associated with increased odds of having prior AP were a younger age at CP diagnosis, white race, abdominal pain, pseudocyst(s) and pancreatic duct dilatation/stricture, while factors associated with a lower odds of having prior AP were exocrine insufficiency and pancreatic atrophy. When compared with patients with 1 episode, those with >1 AP episode were diagnosed with CP an average of 5 years earlier. Conclusions: Nearly three-quarters of patients were diagnosed with AP prior to CP diagnosis. Identifying which AP patients are at-risk for future progression to CP may provide opportunities for primary and secondary prevention.