Erection quality scale: initial scale development and validation

Abstract

OBJECTIVES: The Erection Quality Scale (EQS) is a new, self-report measure for assessing the quality of penile erections. It is intended to complement existing diagnostic and outcome measures (eg, International Index of Erectile Function, Sexual Encounter Profile) in both clinical practice and outcomes research in erectile dysfunction (ED). METHODS: The initial phases of development and psychometric validation of the EQS are described. Specifically, qualitative research in patients and healthy men was used to generate relevant constructs. On the basis of the findings from these phases, and recommendations from an expert panel, seven constructs were selected for inclusion. Multiple items with different formats were drafted to measure each of the key constructs. An iterative process of cognitive testing, item revision, and item reduction was used to identify the 15 most appropriate items and their optimal response scales. This version of the scale was tested in a 200-subject discriminant validity study designed to gather data for a psychometric evaluation. Participants were classified into ED-untreated, ED-treated, and healthy control groups to evaluate the discriminant validity of the measure in men with different levels of erectile function. RESULTS: The study results supported a robust single-factor structure, indicating that the EQS provides an overall index of erection quality. An intraclass correlation coefficient of 0.85 denotes adequate test-retest reliability. Furthermore, the EQS correlated well with existing measures and differentiated patients from the three ED classifications, a preliminary indication of discriminant validity. CONCLUSIONS: The findings presented provide evidence of the scale's potential utility for measuring erection quality in future studies