Negative impact of metabolic syndrome on the responsiveness to sildenafil in Japanese men

Introduction. Several recent studies suggested that the prevalence of erectile dysfunction (ED) was higher in men with metabolic syndrome (MS). Aim. We analyzed the impact of MS on the responsiveness to sildenafil. Methods. A total of 133 ED patients were evaluated for the prevalence of MS and graded on severity of ED. MS was diagnosed according to the International Diabetes Federation (IDF) definition. The severity of ED was evaluated by the International Index of Erectile Function (IIEF) questionnaire. Hormonal parameters were measured for all patients, and the IIEF questionnaire was conducted after administration of eight tablets of 50-mg doses of sildenafil. If the scores to questions 3 and 4 of the IIEF were 4 or higher after administration, the patients were defined as responders to sildenafil. Main Outcome Measures. To clarify the negative impact of MS on the responsiveness to sildenafil. Results. The mean age of the patients was 56.9 years, and 25 patients were diagnosed with MS. The IIEF-erectile function score and the response rate for sildenafil decreased as the number of MS components increased. Logistic regression analysis showed that the presence of MS along with severity of ED and history of pelvic surgery were significant independent risk factors of nonresponse for sildenafil. The hazard ratio for the presence of MS was 3.30 (95% confidence interval [CI]: 1.17-9.73). No meaningful association was observed between total testosterone or free testosterone levels and MS in this population. Conclusion. We demonstrated the negative impact of MS on the responsiveness to sildenafil. Erectile function and response rate for sildenafil decreased as the number of MS components increased.