Cutoff level of prostate volume to predict the efficacy of α1-D/A adrenoceptor antagonist, naftopidil

INTRODUCTION: In lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH) patients, prostate volume (PV) at baseline affects the improvement of International Prostate Symptom Score voiding symptoms (IPSS-VS) by naftopidil (NAF), but not total IPSS (IPSS-TS). To predict the efficacy of NAF, the PV cutoff point was examined using IPSS-VS. MATERIALS AND METHODS: Seventy-seven patients with LUTS/BPH were administrated with NAF 50 mg/day for 4 weeks. Age, PV, IPSS, IPSS quality-of-life (IPSS-QoL), and maximum flow rate (MFR) were evaluated at baseline, and IPSS, IPSS-QoL, and MFR were evaluated after the treatment (at 4 weeks). Responders and nonresponders were divided by IPSS-VS at 4 weeks, and the PV cutoff point was calculated. RESULTS: At baseline, the mean age and PV were 70.7 ± 8.2 years (range, 54–88 years) and 43.3 ± 24.5 mL (range, 20.6–141.7 mL), respectively. After 4 weeks, area under the receiver operating characteristic curve was largest in the patients with <4 points of IPSS-VS. The best standard value to evaluate the efficacy IPSS-VS at 4 weeks was 4 points for the NAF treatment, and the best PV cutoff point was 37.3 mL (sensitivity 60.5%, specificity 71.9%). CONCLUSIONS: PV at baseline was one of the predictive factors which affected the efficacy of NAF for IPSS-VS, and LUTS/BPH patients who had PV more than 37.3 mL indicated poor improvement of IPSS-VS, even if IPSS-TS was improved.