5-α reductase inhibitors and the risk of anaemia among men with benign prostatic hyperplasia: A population-based cohort study.

Unlabelled: 5-α reductase inhibitors (5αRIs) are effective for the treatment of benign prostatic hyperplasia (BPH). However, 5αRIs could lower levels of haemoglobin, increasing the risk of anaemia. The objective of this study was to compare the rate of anaemia between new users of 5αRIs and α-blockers in the UK.

Methods: We conducted a matched, active comparator, new-user cohort study using the Clinical Practice Research Datalink. The study population consisted of men aged ≥40 years with incident BPH who initiated 5αRIs between 1998 and 2019 and were matched 1:1 on propensity score to new users of α-blockers. Anaemia was defined by a measured haemoglobin <130 g/L. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for anaemia.

Results: Our study cohort included 9429 new users of 5αRIs and 9429 matched new users of α-blockers. Their median durations of follow-up were 136 days (interquartile range: 54-336 d) and 77 days (interquartile range: 58-236 d), respectively. A total of 2865 5αRIs users and 2407 α-blocker users developed incident anaemia, representing rates of 37.3 (95% CI: 33.6-41.3) and 42.0 (95% CI: 38.1-46.2) per 100 person-years, respectively. The use of 5αRIs was not associated with an increased risk of anaemia compared to the use of α-blockers (HR: 0.95, 95% CI: 0.90-1.00). Similarly, we did not observe an increased risk of mild, moderate, or severe anaemia.

Conclusion: The use of 5αRIs was not associated with an increased risk of anaemia compared to the use of α-blockers among men with BPH.