Psychometric validation of the Confidence in Performing Sexual Intercourse Questionnaire and Difficulty in Performing...

The objective of this study was to perform psychometric testing of two new patient-reported outcome instruments (PROs), the Confidence in Performing Sexual Intercourse Questionnaire (CPSIQ) and the Difficulty in Performing Sexual Intercourse Questionnaire (DPSIQ). The new PROs were administered at non-drug, run-in, baseline and end point in men with erectile dysfunction (ED) participating in a randomized clinical trial of ED treatment (Study 1, n=291) and two times within 2 weeks to men with ED participating in a web-based survey (Study 2, n=71). Psychometric tests included factor analysis, internal consistency and test-retest reliability, construct validity and responsiveness. Analysis of data from Study 1 participants (74% ≤65 years, 83% Caucasian and 75% with moderate ED) suggested one-factor solutions for both PROs with Cronbach's α >0.88. CPSIQ and DPSIQ total scores discriminated between ED severity groups showed worsening after a 4-week non-drug, run-in period, and showed improvement after 12 weeks of ED treatment (all, P<0.05). Intraclass correlation coefficients calculated for the CPSIQ and DPSIQ, using data from Study 2 participants (82% ≤65 years, 90% Caucasian and 66% with mild ED), were 0.56 and 0.83, respectively. The CPSIQ and DPSIQ show potential for augmenting existing treatment outcome measures used in the evaluation of ED treatment.