The cutoff value of transitional zone index predicting the efficacy of dutasteride on subjective symptoms in patients with benign prostate hyperplasia

We investigated the efficacy of dutasteride add-on therapy to α-1 adrenoceptor antagonists in patients with benign prostate hyperplasia (BPH) in relation to the transitional zone index (TZI) and evaluated the cutoff value of TZI that predicted improvements of subjective symptoms at 6 months.Male BPH patients with prostate volume (PV) ≥ 30 mL receiving dutasteride 0.5 mg/d for 6 months as add-on therapy along with α-1 adrenoceptor antagonists were enrolled. PV, transitional zone volume (TZV), TZI, International Prostate Symptom Score (IPSS), and uroflowmetry parameters before and at 6 months with dutasteride add-on treatment were evaluated.Eighty-three patients were included. The changes of total IPSS, IPSS voiding subscore, IPSS quality of life score, and voided volume were significantly correlated with TZI. Among baseline parameters, TZV and TZI were significantly associated with the changes of total IPSS in univariate analysis, and only TZI remained as an independent predictive factor for improving total IPSS in multivariate analysis (odds ratio -8.3, P = .048). The cutoff point of TZI for predicting an improvement of the total IPSS by 6 points or more was 0.67 (area under the curve 0.71, sensitivity 0.62, specificity 0.79).A higher TZI was significantly associated with improvement of subjective symptoms but not uroflowmetric findings for BPH patients with 6 months of dutasteride add-on therapy along with α-1 adrenoceptor antagonists, and the predictive value of TZI for effective dutasteride add-on therapy was higher than 0.67. BPH patients using α-1 adrenoceptor antagonists with a TZI higher than 0.67 can be good candidates for add-on dutasteride therapy.