Computed tomography features of recurrent acute pancreatitis based on different etiologies

Acute pancreatitis (AP), recurrent acute pancreatitis (RAP), and chronic pancreatitis (CP) are increasingly viewed as stages in a continuous disease spectrum when the underlying etiology remains unresolved. Previous studies have investigated the effect of different etiologies on AP severity, but few have specifically examined the clinical and radiologic characteristics of RAP stratified by etiology. This study aimed to investigate the computed tomography (CT) features of RAP stratified by etiology.

We retrospectively analyzed the data of 683 RAP patients who underwent contrast-enhanced computed tomography (CECT) at three tertiary hospitals between January 2015 and December 2019. The patients were categorized into five etiologic groups: alcoholic, cholelithiasis-related, hypertriglyceridemia-related, multifactorial, and idiopathic. Clinical and imaging data, including demographic data, 2012 revised Atlanta classification (RAC), Acute Physiology and Chronic Health Evaluation (APACHE) II scores, modified computed tomography severity index (MCTSI) scores, extrapancreatic inflammation on computed tomography (EPIC) scores, the presence and extent of pancreatic necrosis, and local complications, were compared across groups using Kruskal-Wallis and Chi-squared (or Fisher's exact) tests, with Bonferroni correction for multiple comparisons.

Among the 683 patients {449 male, 234 female; median age: 45 years [interquartile range (IQR), 39-52 years]; median hospital stay: 11 days (IQR, 7-15 days)} included in the study, hypertriglyceridemia was the most common cause of RAP (50.95%), followed by idiopathic causes (18.74%), cholelithiasis (15.37%), alcoholism (9.37%), and multiple causes (5.56%). Patients with hypertriglyceridemic or multifactorial RAP had higher triglyceride [median (IQR): 17.99 (12.12-25.77) vs. 1.33 (0.86-2.00) mmol/L] and blood glucose [median (IQR): 10.55 (7.44-14.33) vs. 7.43 (5.74-10.12) mmol/L] levels, as well as a higher prevalence of pre-existing diabetes (30.46% vs. 9.52%) (all P<0.001). Compared to the patients with biliary RAP, those with hyperlipidemic RAP exhibited milder CT features, including lower rates of necrotizing pancreatitis (NP) (33.05% vs. 48.57%), combined necrosis (CN) (25.57% vs. 40.00%), pancreatic necrosis >50% (3.74% vs. 14.29%), and severe disease (23.85% vs. 40.00%) as defined by the MCTSI (all P<0.05). These patients also had lower EPIC scores [median (IQR): 3 (2-5) vs. 4 (2-5.5)] and shorter hospital stays [median (IQR): 10 (7-15) vs. 13 (9.5-18) days] (both P<0.05). No significant differences in the severity indicators were observed among alcoholic, multifactorial, and idiopathic groups. Alcohol-related RAP occurred predominantly in males (96.9%), while biliary RAP was more frequent in older female patients (both P<0.05).

RAP presents with distinct clinical and CT features depending on its etiology. Hypertriglyceridemic RAP is associated with milder disease severity than biliary RAP. Our findings provide new insights into the etiology-specific manifestations of RAP, and may inform future research on its underlying mechanisms and long-term outcomes.