A population-based nested case-control study: the use of 5-alpha-reductase inhibitors and the increased risk of osteoporosis diagnosis in patients with benign prostate hyperplasia.

Background: 5-alpha-reductase inhibitors (5ARIs) are the potent androgen responsible for the development and enlargement of the prostate gland by decreasing dihydrotestosterone (DHT). This results in inhibition of the conversion of testosterone to dihydrotestosterone and markedly suppresses serum dihydrotestosterone levels. Testosterone replacement therapy improves bone density in men with hypogonadal osteoporosis. This study explores the possible association between the use of two typical 5ARIs (finasteride and dutasteride) and the subsequent risk of osteoporosis diagnosis.

Methods: We identified 1352 osteoporosis diagnosis cases and 5387 control cases without osteoporosis diagnosis from the claims data for patients with benign prostate hyperplasia (BPH), which are collected in the Taiwanese National Health Insurance Research Database (NHIRD). Four controls were frequency matched to each case according to age (every 5 years) and diagnosis date. We measured the effect of 5ARIs and determined the adjusted odds ratios (ORs) with 95% confidence intervals (CIs).

Results: We observed a 1·52-fold increase in osteoporosis diagnosis among patients with BPH using finasteride (95% CI, 1·01-2·30). Furthermore, a dosage analysis showed that higher doses of finasteride were associated with higher osteoporosis diagnosis risk (OR = 1·68; 95% CI, 1·01-2·81), relative to the patients not using 5ARIs.

Conclusion: This population-based nested case-control study suggests that the use of finasteride can increase the risk of osteoporosis diagnosis among patients with BPH. The effects were more prominent in patients using higher doses of finasteride.