Introduction: The absence of a single brief measure that assesses function and health-related quality of life (HRQoL) hinders evaluation of the sexual experience in men with erectile dysfunction (ED).
Aim: To psychometrically analyze the Sexual Experience Questionnaire (SEX-Q).
Methods: Two data sets were studied. A randomized, double-blind, placebo-controlled trial of flexible-dose sildenafil for ED treatment provided the final clinical trial data set (213 men enrolled, 4 of whom did not receive treatment) and the interim clinical trial data set (190 men screened and 165 men enrolled). The survey data set consisted of 902 respondents to a U.S. community health survey, of whom two-thirds had ED and one-third did not.
Main outcome measures: Quality and distribution of responses, comparative fit, item-level discriminant testing, internal consistency (Cronbach alpha), test-retest reliability (intraclass correlation coefficient), known-groups validity (vs. International Index of Erectile Function [IIEF] ED severity groups), convergent validity (Pearson correlation coefficients with scores on the IIEF, Self-Esteem and Relationship [SEAR] questionnaire, and Quality of Erection Questionnaire [QEQ]), responsiveness, and clinically important difference (CID).
Results: The original 15 items were reduced to 12 items in three domains (erection, individual satisfaction, and couple satisfaction), which demonstrated good quality responses for all items; a strong factor structure; excellent internal consistency; good test-retest reliability; clear known-groups validity across the severity groups; moderate to strong convergent validity against the IIEF, SEAR, and QEQ; and high treatment responsiveness. The estimated CID ranged from 16.0 to 22.3 across domains.
Conclusions: The SEX-Q is the first questionnaire to solely and exclusively combine functional and HRQoL concepts (erection, individual satisfaction, and couple satisfaction domains) in a brief questionnaire, which allows a more focused and less burdensome evaluation of the sexual experience, making it a potentially useful measure for clinical trial research.