Free combination of dutasteride plus tamsulosin for the treatment of benign prostatic hyperplasia in South Korea: analysis of drug utilization and adverse events using the National Health Insurance Review and Assessment Service database.

Objective: To assess the use and safety of free combination therapy (dutasteride and tamsulosin), dutasteride monotherapy, or tamsulosin monotherapy in patients with benign prostatic hyperplasia (BPH).

Methods: This non-interventional retrospective cohort study used claims data from the Korea Health Insurance Review and Assessment-National Patient Sample database. Patients with BPH ≥ 40 years of age receiving combination therapy (dutasteride 0.5 mg and tamsulosin 0.4 mg daily) or dutasteride 0.5 mg, or tamsulosin 0.4 mg daily dose between 2012 and 2017 were included. The frequency, duration of treatment and risk of any adverse event (AE) or serious AE (SAE) was compared for combination therapy versus each monotherapy using non-inferiority testing.

Results: Of 14,755 eligible patients, 1529 (10.4%) received combination therapy, 6660 (45.1%) dutasteride monotherapy, and 6566 (44.5%) tamsulosin monotherapy. The proportion of patients treated with combination therapy exceeded the pre-specified 3% threshold for 'frequent' use. Safety results indicated a similar risk of any AE and SAE irrespective of treatment group. The adjusted relative risk for any AE over the treatment observation period comparing combination therapy with dutasteride monotherapy was 1.07 (95% confidence interval [CI] 1.03, 1.12), and with tamsulosin monotherapy was 0.98 (95% CI 0.95, 1.02) demonstrating non-inferiority. The adjusted relative risk for any SAE was 1.07 (95% CI 0.66, 1.74) and 0.90 (95% CI 0.56, 1.45), compared with dutasteride and tamsulosin monotherapy, respectively. Although the SAE results did not statistically demonstrate non-inferiority of combination therapy based on pre-specified margins, the 95% CI for the risk ratio estimates included the null with a lower limit below the non-inferiority margins, indicating no meaningful differences in SAE risk between groups. Absolute SAE risks were low.

Conclusion: Combination therapy with dutasteride and tamsulosin is frequently used in real-world practice in South Korea for treatment of BPH and demonstrates a safety profile similar to either monotherapy.