Bother and distress associated with Peyronie's disease: validation of the Peyronie's disease questionnaire

Abstract

Purpose: We validated the Peyronie's Disease Questionnaire (http://www.auxilium.com/PDQ), a 15-question self-reported survey that measures the impact and severity of Peyronie's disease symptoms in 3 domains, including 1) psychological and physical symptoms, 2) penile pain and 3) symptom bother.

Materials and methods: We used baseline data from 2 phase 3 clinical trials (334 and 345 patients, respectively) of collagenase clostridium histolyticum treatment for Peyronie's disease associated penile curvature and bother. Collected data included PDQ domain scores, International Index of Erectile Function scores, objective penile curvature measures and patient reported Peyronie's disease symptom severity. Psychometric analyses included confirmatory factor analysis, inter-item reliability, and tests of convergent and discriminant validity, all related to the overall construct validity of the scale.

Results: Confirmatory factor analysis supported the conceptual framework of the PDQ with 3 confirmed subdomains. Each scale showed good consistency, ie internal reliability (each Cronbach α >0.70). Convergent and discriminant validity were noted in the pattern of associations between PDQ domains and other Peyronie's disease measures. PDQ domain scores significantly differed between patients with vs without erectile dysfunction and between patients with vs without Peyronie's disease related symptom distress, further supporting PDQ construct validity.

Conclusions: This study confirms the conceptual framework, factor structure, and convergent and discriminant validity of the PDQ psychological and physical symptoms, penile pain, and symptom bother domains. Used in conjunction with objective penile curvature measurements, the PDQ can serve as a valuable diagnostic tool or outcome measure to assess treatment related improvements in Peyronie's disease symptoms.

Keywords: CFA; CFI; ED; IIEF; International Index of Erectile Function; PD; Peyronie's disease; QOL; RMSEA; TLI; Tucker-Lewis index; comparative fit index; confirmatory factor analysis; erectile dysfunction; penile induration; penis; quality of life; questionnaires; root mean square error of approximation; sexual dysfunction, physiological; validation studies.