[Psychometric validation of the International Index of Erectile Function in patients with erectile dysfunction in Perú]. / Validación psicométrica del instrumento Índice Internacional de Función Eréctil en pacientes con disfunción eréctil en Perú.

OBJECTIVES: To perform the psychometric validation of the International Index of Erectile Function (IIEF) in patients with erectile dysfunction. MATERIALS AND METHODS: Prospective case series to evaluate the validity and the reliability of the scale. RESULTS: More than 90 % of experts considered that the IIEF questions evaluated the domains and the construct (content validity). There was a perfect concordance between the expert evaluation and the IIEF results (criteria validity, Kappa = 1). Significant differences were found in the score media by domains between patients with and without ED but when severity was evaluated, only differences in the erectile function domain were found (discriminatory validity). The Chronic Prostatitis Symptom Index (ISPC) and the IIEF showed divergent results (Kappa < 0.01, p = 0.44) in relation with the severity and the total scores showed no correlation (divergent validity) (r(s) = -0.22, p = 0.16). The correlation coefficients by domains were mild to moderate and the correlation between the total scores was high (rs = 0.8, p < 0.001) (test retest repeatability). A high degree of internal consistency with Cronbach's alpha values > 0.8 in the five domains was found. CONCLUSIONS: The cross-culturally validated IIEF in Peru is a valid and reliable instrument for its local use in the fields of clinics and research.