(P-632) Comparison of the Incidence of Acute Pancreatitis Among New Users of Fluoxetine, Citalopram, and Other Selective Serotonin Reuptake Inhibitors: A Danish Register-based Cohort Study

Background: Acute pancreatitis is among the most common gastrointestinal disorders leading to hospital admission. Evidence on the associations between selective serotonin reuptake inhibitors (SSRIs) use and acute pancreatitis is currently sparse and inconsistent. Fluoxetine use has been suggested to increase the risk of acute pancreatitis.

Objectives: This study aims to evaluate the association between fluoxetine and acute pancreatitis by comparing the incidence in fluoxetine users to the incidence in users of citalopram or other SSRIs, adjusting for multiple potential confounders.

Methods: We conducted a register-based cohort study using Danish healthcare data from 1996 to 2016. The cohort of interest was new users of fluoxetine (washout period of 1 year). The two control groups were new users of citalopram and new users of other SSRIs (excluding fluoxetine). The outcome was a 5-year incident hospitalization with a primary diagnosis of acute pancreatitis. We used an intention-to-treat approach following patients for a maximum of six months from treatment initiation to the outcome or censoring (event of pancreatic cancer, chronic pancreatitis, or other pancreatic disorders, emigration, death, or end of study period). Cox regression analyses were performed, estimating hazard ratios (HRs) and 95% CIs adjusted for age/sex and propensity score deciles estimated from predefined comorbidities and co-medications.

Results: In total, 78,259, 622,876, and 1,026,688 new users of fluoxetine, citalopram, and other SSRIs were included. The mean age in the entire cohort was 52.9 (standard deviation 20.4). Among new users of fluoxetine, citalopram, and other SSRIs, there were 25, 202, and 314 events of acute pancreatitis with incidence rates of 6.57 (4.25-9.70), 6.82 (5.92-7.83), and 6.42 (5.73-7.17) per 10,000 person-years, respectively. The HRs (95% CIs) in the age/sex and propensity score decile-adjusted models were 1.08 (0.71-1.64) and 1.06 (0.70-1.62) among new users of fluoxetine compared to citalopram and 1.11 (0.74-1.67) and 1.09 (0.72-1.64) compared to other SSRIs, respectively.

Conclusions: Fluoxetine was not associated with an increased risk of acute pancreatitis compared to citalopram or other SSRIs. Further research is needed to determine whether there is a class effect of SSRIs on pancreatitis risk.