Postmenopausal hormone replacement therapy and risk of acute pancreatitis: a prospective cohort study.

BACKGROUND Several case reports have suggested that women's use of exogenous sex hormones is associated with acute pancreatitis; however, relevant epidemiologic data are sparse. We examined the association between postmenopausal hormone replacement therapy and risk of acute pancreatitis. METHODS We conducted a prospective study involving 31,494 postmenopausal women (aged 48-83 yr) from the population-based Swedish Mammography Cohort. Participants completed a baseline questionnaire in 1997 assessing their use of hormone replacement therapy. We linked the cohort to the hospital-based Swedish National Patient Register to determine hospital admissions for acute pancreatitis through 2010. Relative risks (RRs) were calculated using Cox proportional hazard models. RESULTS Over a total follow-up of 389,456 person-years, we identified 237 cases of incident acute pancreatitis. The age-standardized incidence rates per 100,000 person-years were 71 cases among women who had ever used hormone replacement therapy and 52 cases among women who had never used such hormones. Among ever users of hormone replacement therapy, the multivariable-adjusted RR of acute pancreatitis was 1.57 (95% confidence interval [CI] 1.20-2.05) compared with never users. The risk did not differ by current or past use, but it seemed to be higher among women who used systemic therapy (RR 1.92, 95% CI 1.38-2.66) and among those with duration of therapy of more than 10 years (RR 1.87, 95% CI 1.11-3.17). INTERPRETATION Use of postmenopausal hormone replacement therapy was associated with increased risk of acute pancreatitis. Physicians should consider this potential increase in risk when prescribing such therapy.