To assess the psychometric properties of the Spanish version of the Index of Spouse Abuse (ISA), and validate it against external criteria of intimate partner violence (IPV).

A case control, transversal study was designed. Spanish version of the ISA was administered to 405 women (223 controls and 182 IPV cases). Spanish items weights were developed. Internal consistency was assessed through Cronbach's alfa, and factor structure by means of principal component analysis (PCA). Receiver operating characteristic (ROC) analysis was used to validate the ISA against external criteria.

PCA analysis yielded two factors that accounted the 69% of variance, and reproduced partially the original factors: physical (ISA-P) and non-physical (ISA-NP). Internal consistency coefficients oscillated between 0,88 and 0,98. For the ISA global score, the AUC value for detecting IPV was 0,99; and 0,89 for detecting physical IPV. The optimal cut-off scores were 13 for detecting IPV, and 15 for detecting physical IPV. For the ISA subscales, 6 was the optimal cut-off score for the ISA-P, and 13 was the optimal cut-off for the ISA-NP.

The Spanish version of the ISA is a valid and reliable instrument for detecting and measuring the intensity of the IPV in Spanish women population.