Efficacy and factors associated with successful outcome of sildenafil citrate use for erectile dysfunction after radical prostatectomy.

OBJECTIVES To assess the efficacy and factors associated with successful treatment of sildenafil citrate for erectile dysfunction after radical prostatectomy (RP). METHODS Of the 470 patients who underwent RP at our institution between July 1998 and January 2000, 227 (48%) sought treatment for erectile dysfunction, and 174 (37%) were prescribed sildenafil citrate. The starting dose was 50 mg, which was increased to 100 mg if the patient did not have a positive response. Of the 174 patients, 104 (59.8%) had undergone a bilateral nerve-sparing (NS) procedure, 28 (16.1%) had undergone a unilateral NS procedure, and 42 (24.1%) had undergone a non-NS procedure. Erectile function was assessed by the abridged five-item version of the International Index of Erectile Function questionnaire, referred to as the Sexual Health Inventory for Men (SHIM), at baseline and 1 year after sildenafil use. The patients' charts were retrospectively reviewed to find factors associated with a successful outcome, which was defined as successful vaginal intercourse. Association with success was assessed by chi-square analysis and the Cochran Armitage test for trend. Bonferroni correction for multiple comparisons was used, with an overall significance level of 0.05 for each factor assessed. RESULTS The mean age was 60.1 +/- 6.25 years, and the mean interval from RP to drug use was 3 months. After treatment with sildenafil, 100 (57%) of 174 patients responded to the drug: 79 (76%) of 104 in the bilateral NS group, 15 (53.5%) of 28 in the unilateral NS group, and 6 (14.2%) of 42 in the non-NS group. SHIM analysis showed that the magnitude of the improvement was greater in the bilateral NS group (19.97 +/- 1.12) than in the unilateral NS (15.89 +/- 3.38) or non-NS (10.06 +/- 2.0) groups (P <0.020). Four factors were significantly associated statistically with a successful outcome: the presence of at least one neurovascular bundle, a preoperative SHIM score of 15 or greater, age 65 years old or younger, and interval from RP to drug use of more than 6 months (P <0.001). CONCLUSIONS The efficacy of sildenafil citrate after RP correlated with the degree of neurovascular bundle preservation, preoperative erectile function status, age, and interval before starting treatment.