Relationship between patient self-assessment of erectile function and the erectile function domain of the international index of erectile function

Abstract

Objectives. To assess the validity of severity classes on the erectile function (EF) domain of the International Index of Erectile Function by determining their relationship with the self-assessment of EF, before and after treatment, in an independent cohort of patients. Methods. Two hundred forty-seven men with clinically diagnosed erectile dysfunction (ED) and in a stable heterosexual relationship were enrolled in a randomized, double-blind, multicenter, placebo-controlled, parallel-group, 12-week, flexible-dose study. Patients assessed their degree of ED as severe, moderate, minimal/mild, or no problem at baseline and after treatment. They also responded to the six questions of the EF domain, with the total score indicating the following degrees of ED: severe, EF score 1 to 10; moderate, EF score 11 to 16; mild to moderate, EF score 17 to 21; mild, EF score 22 to 25; and no ED, EF score 26 to 30. Descriptive profiles of the two diagnostic instruments were compared. The correlations between the instruments were evaluated with Kendall’s tau-b at baseline, after treatment at 12 weeks, and at change from baseline. Results. The two measures gave generally similar descriptive profiles of ED severity. The correlations were 0.65 (95% confidence interval 0.57 to 0.73) at baseline, 0.86 (95% confidence interval 0.83 to 0.89) after 12 weeks of treatment, and 0.73 (95% confidence interval 0.67 to 0.79) at change from baseline. Conclusions. The moderate-to-high correlation between the patients’ self-assessment of EF and the EF domain of the International Index of Erectile Function provides a validation of this domain for the reliable diagnostic classification of ED severity.