Background:
Lower urinary tract symptoms (LUTS) are common in aging men, most often due to benign prostatic hyperplasia (BPH), and significantly impair quality of life. α1-adrenoceptor antagonists are first-line therapy, with tamsulosin being the most widely prescribed. However, ejaculatory dysfunction (EjD) is a frequent adverse effect that negatively affects adherence. Optimal dosing strategies that maintain urinary efficacy while reducing EjD are not well defined, and current guidelines provide no recommendations regarding alternate-day dosing.
Patients and Methods:
This multicenter, randomized, open-label, assessor-blinded, parallel-group, non-inferiority trial will enroll men aged ≥50 years with LUTS/BPH and baseline IPSS ≥8. Participants will be randomized 1:1 to receive tamsulosin 0.4 mg once daily or every other day for 24 weeks. The primary endpoint is change in International Prostate Symptom Score (IPSS) from baseline to Week 24. Non-inferiority will be concluded if the upper bound of the two-sided 95% confidence interval (CI) for the between-group difference in mean IPSS change (EOD - Daily) is ≤ +3 points.
The key secondary endpoint is change in Male Sexual Health Questionnaire-Ejaculatory Dysfunction (MSHQ-EjD) total score from baseline to Week 24, tested for superiority only if IPSS non-inferiority is established. Additional secondary endpoints include maximum urinary flow rate (Qmax), post-void residual volume (PVR), IPSS-Quality of Life score, and ejaculatory adverse-event rates.
Sample Size and Analysis:
Assuming an SD of 6 for IPSS change, a non-inferiority margin of +3, one-sided α of 0.025, and 90% power, approximately 85 evaluable patients per arm are required for the primary endpoint. To ensure adequate power for EjD outcomes and allow for 20% attrition, 144 participants per arm (288 total) will be randomized. Analyses will follow the intention-to-treat principle with per-protocol sensitivity analyses. Primary inference will use ANCOVA or MMRM adjusted for baseline score, age, and study site, with multiple imputation for missing data.
Expected Outcomes:
This trial will provide the first adequately powered multicenter evidence on whether every-other-day tamsulosin preserves non-inferior LUTS control while improving ejaculatory outcomes, potentially supporting a simple and cost-effective strategy to enhance tolerability and adherence in men with LUTS/BPH.