Validation of the erection hardness score.

INTRODUCTION Erection hardness is a fundamental component of erectile function, and is a very specific and easily monitored outcome. The Erection Hardness Score (EHS) is a single-item, patient-reported outcome (PRO) for scoring erection hardness. AIMS The aim of this article is to report the psychometric validation of the EHS. METHODS The dataset (N = 307) was from a multinational sildenafil trial (efficacy in the treatment of erectile dysfunction [ED]) with a 2-week screening phase, a 6-week double-blind, placebo-controlled treatment phase, and a 6-week open-label extension. MAIN OUTCOME MEASURES Test-retest reliability (intraclass correlation coefficient), quality and distribution of responses, known-groups validity (ability to differentiate between ED severity groups defined by the International Index of Erectile Function [IIEF] questionnaire), convergent validity (Pearson correlation coefficients with domain scores of the IIEF and the Quality of Erection Questionnaire [QEQ]), treatment responsiveness, and clinically important difference. RESULTS The EHS demonstrated good test-retest reliability, acceptable quality and distribution of responses, known-groups validity against the IIEF (including clear differentiation between normal and impaired erectile function), moderate-to-strong convergent validity against the prespecified domains of the IIEF and QEQ, and high treatment responsiveness. CONCLUSION The EHS has desirable measurement properties, including being highly responsive to treatment. This one-item PRO is robust and easy to use for evaluating erection hardness. Psychometric analysis supports the use of the EHS as a simple, reliable, and valid tool for the assessment of erection hardness in clinical trials research.