The Development of a Validated Patient Reported Outcome Measure (PROM) for Penile Curvature Surgery
Subjective measures of successful penile curvature surgery are poorly defined. This study describes the 5 year development of a PROM for patients with stable Peyronie's disease (PD) undergoing corrective surgery in as single centre.
Semi-structured interviews with PD patients identified four domains for assessment - penile appearance (PA), erectile function (EF), sexual relationships and generic quality of life (GQoL). A multidisciplinary RAND consensus group of UK andrologists defined the initial item-specific PROM 1. Questions about PA were created de-novo. EF and QoL questions were modified for PD based on IIEF and EQ5-D questionnaires respectively. PROM 1 was piloted on all patients being considered for PD surgery at a single centre over a 3 year period with test-retest design. Following statistical assessment for validity, and modification based on patient feedback, a second iteration PROM 2 was created and tested over a further 2 year period. Internal consistency of questions was assessed using Cronbach's alpha to verify each domain reliably measured the same latent variable. Wilcoxon Signed Rank test was used to assess consistency between test and retest scores. Variability and bias was assessed using a Bland Altman plot.
The baseline PROM 2 was self-completed pre-operatively in a test-retest fashion by 56 men who all underwent penile curvature correction. All patients completed the study with over 90% response rates for each question. Cronbach's alpha for Penile Appearance construct was 0.31 rising to 0.44 omitting pain subjectivity. Cronbach's alpha for ED, sexual relationships and GQoL domains were 0.98, 1.33 and 0.70 respectively. Wilcoxon Signed Rank test for the penile curvature construct indicated no significant difference between the test and re-test scores (P
Relationship, ED and QoL questions were answered consistently and demonstrated content validity and reliability. Penile length and pain were raised as bothersome factors in the initial consensus. However, patients gave conflicting answers within the appearance and curvature domain. Therefore, a third iteration, PROM 3 is currently being tested with modifications to improve this domain whilst maintaining a user-friendly design.