BACKGROUNDTo evaluate temporal trends in gender, etiology, severity, outcomes, cost and median length of stay (MLS) in patients with acute pancreatitis (AP) in a third-tier Chinese city.METHODSPatients with AP admitted to a university hospital between January 2013 and December 2021. Relationships between etiology, prevalence of severe acute pancreatitis (SAP) and survey years were investigated by joinpoint regression analysis.RESULTSA total of 5459 (male 62.3%) patients with AP were included. Between January 2013 and December 2021, we observed: (a) the prevalence of biliary diseases-related AP was stable, while the prevalence of hypertriglyceridemia (HTG)-associated AP (Ptrend = 0.04) and alcohol-associated AP (Ptrend < 0.0001) both increased; (b) there was an increase in crude prevalence of SAP from 4.97% to 12.2% between 2013 and 2021 (Ptrend < 0.0001); (c) compared to female populations, male gender had a higher prevalence of AP; (d) there was a decrease in MLS from 11 days to 8 days (Ptrend < 0.0001) and in median cost of hospitalization (MCH) for all patients (from 20,166 to 12,845 YUAN) (Ptrend < 0.0001); (e) the overall in-hospital mortality rate was 1.28% (70/5459) for patients with AP. There was no statistically significant in the time trend of mortality during the study period (Ptrend = 0.5873). At multivariate analysis, survey year was associated with prevalence of SAP after adjustment by age and biliary diseases (OR: 1.07; 95% CI: 1.03-1.12). Based on the stratification by severity of disease, the decrease of MLS and MCH was more significant in non-SAP vs. SAP patients.CONCLUSIONSOver the observational period, the proportion of male patients with AP, prevalence of age-adjusted rate of HTG and alcohol-associated AP and SAP increased, while MLS and MCH for all patients decreased, and the time trend of mortality of AP was stable.