Background and Aim: The clinical course and prognosis of medically managed patients with small duct and large duct chronic pancreatitis (CP) has been scarcely investigated. We inves- tigated all-cause mortality and progression of endocrine and exocrine function in a medically managed cohort of patients with small duct CP and compared them to patients with large duct CP.

Methods: This was a retrospective cohort study of 198 consecutive patients with definitive CP according to M-ANNHEIM criteria. Patients were classified as large or small duct cases based on pancreatic duct morphology on cross sectional imaging. We compared all-cause mortality and rates of diabetes and exocrine insufficiency (EPI) between patient subgroups using Kaplan-Meier and multivariate-adjusted Cox Proportional Hazard Models. In a subgroup of patients with follow-up imaging studies, changes in anteroposterior (AP) diameter of the pancreatic head (n=120) and body (n=122) as well as changes in pancreatic duct morphology (n=121) was studied.

Results: The mean age of subjects were 58 ± 12 years and 70% were male. Large duct CP was seen in 75 patients (38%) and small duct CP by 123 patients (62%). The five-year mortality rate was compared between patient subgroups (HR: 1.07; 95% CI 0.56–2.07) as was the rate of new onset diabetes (HR: 1.55; 95% CI 0.77–3.13). In contrast, new onset of EPI was more prevalent in patients with large duct CP (HR: 1.77; 95% CI 1.10–2.86; P=0.019). Large duct CP was also associated with greater loss of pancreatic parenchyma in the head (coefficient -2.9 mm; 95% CI -4.0– -1.6; P<0.001). Seventeen (14%) with follow-up imaging changed their pan- creatic duct morphology at follow-up, with the majority of patients developing large duct dis- ease (82%).
Conclusion: Medically managed patients with large duct CP have an excess risk of EPI and pancreatic atrophy compared to their counterparts with small duct CP.