The Cardiovascular Safety of Dutasteride

Purpose Randomized controlled trials suggest an increased risk of heart failure with dutasteride, which inhibits both the type 1 and type 2 isoforms of 5α-reductase. In contrast, no such association has been suggested for finasteride, which selectively inhibits the type 2 isoform. We investigated the risk of cardiovascular events among patients receiving dutasteride relative to finasteride. Materials and Methods We performed a population based cohort study of Ontario men 66 years old or older who commenced treatment with dutasteride or finasteride between October 1, 2005 and March 31, 2015. For each individual treated with dutasteride, we identified 1 treated with finasteride, matching on a propensity score and calendar quarter of treatment initiation to account for temporal changes in prescribing. The primary outcome was hospitalization for heart failure. Secondary analyses were done to examine acute myocardial infarction and stroke. Cox proportional hazards regression was used to adjust for differences between groups. Results We studied 36,311 men who commenced dutasteride and 36,311 treated with finasteride. In the primary analysis, we found no difference in the risk of heart failure among patients receiving dutasteride relative to those receiving finasteride (adjusted HR 0.98, 95% CI 0.88–1.08). Similarly, we found no difference in the risk of acute myocardial infarction (HR 0.94, 95% CI 0.82–1.08) or stroke (HR 1.03, 95% CI 0.88–1.20). Conclusions In this population based cohort study of more than 72,000 older men, dutasteride was not associated with an increased risk of cardiovascular events relative to finasteride.