Natural course of chronic pancreatitis and predictors of its progression.

BACKGROUND: The natural course of chronic pancreatitis(CP) and its complications has been inadequately explored. We aimed to describe the natural history and factors affecting the progression of alcoholic(ACP), idiopathic juvenile(IJCP) and idiopathic senile(ISCP) variants of CP.

METHODS: This study was a retrospective analysis from a prospectively maintained database of patients with CP following up at a tertiary care centre from 1998 to 2019. Cumulative rates of pain resolution, diabetes, steatorrhea, pseudocysts and pancreatic cancer were computed using Kaplan-Meier analysis, and the factors affecting their incidence were identified on multivariable-adjusted Cox-proportional-hazards model.

RESULTS: A total of 1415 patients were included, with 540(38.1%) ACP, 668(47.2%) IJCP and 207(14.6%) ISCP with a median follow-up of 3.5 years(Inter-quartile range: 1.5-7.5 years). Diabetes occurred at 11.5, 28 and 5.8 years(p < 0.001) while steatorrhea occurred at 16, 24 and 18 years(p = 0.004) after onset for ACP, IJCP and ISCP respectively. Local complications including pseudocysts occurred predominantly in ACP(p < 0.001). Ten-year risk of pancreatic cancer was 0.9%, 0.2% and 5.2% in ACP, IJCP and ISCP, respectively(p < 0.001). Pain resolution occurred more frequently in patients with older age of onset[Multivariate Hazard Ratio(HR):1.7(95%CI:1.4-2.0; p < 0.001)], non-smokers[HR:0.51(95%CI:0.34-0.78); p = 0.002] and in non-calcific CP[HR:0.81(0.66-1.0); p = 0.047]. Occurrence of steatorrhea[HR:1.3(1.03-1.7); p = 0.028] and diabetes[HR:2.7(2.2-3.4); p < 0.001] depended primarily on age at onset. Occurrence of pancreatic cancer depended on age at onset[HR:12.1(4.7-31.2); p < 0.001], smoking-history[HR:6.5(2.2-19.0); p < 0.001] and non-alcoholic etiology[HR:0.14(0.05-0.4); p < 0.001].

CONCLUSION: ACP, IJCP and ISCP represent distinct entities with different natural course. Age at onset of CP plays a major prognostic role in all manifestations, with alcohol predominantly causing local inflammatory complications.