Validity of the WHO VAW study instrument for estimating gender-based violence against women.

OBJECTIVE: To validate the instrument of the World Health Organization Violence Against Women (WHO VAW) study on psychological, physical and sexual violence against women perpetrated by intimate partners. METHODS: This was a cross-sectional study conducted in several countries between 2000 and 2003, including Brazil. Representative random samples of women aged 15-49 years with intimate partners were selected, living in the city of São Paulo (n = 940) and in the Zona da Mata, Pernambuco (n = 1,188), southeastern and northeastern regions, respectively. Exploratory factor analysis on questions relating to violence was performed (four psychological, six physical and three sexual questions), with varimax rotation and creation of three factors. Cronbach's alpha was calculated to analyze the internal consistency. To validate through extreme groups, mean scores (0 to 13 points) for violence were tested in relation to the following outcomes: self-rated health, daily activities, presence of discomfort or pain, suicidal ideation or attempts, heavy alcohol consumption and presence of common mental disorders. RESULTS: Three factors were defined, with similar accumulated variance (0.6092 in São Paulo and 0.6350 in the Zona da Mata). For São Paulo, the first factor was determined by physical violence, the second by sexual violence and the third by psychological violence. For the Zona da Mata, the first factor was formed by psychological violence, the second by physical violence and the third by sexual violence. Cronbach's alpha coefficients were 0.88 in São Paulo and 0.89 in the Zona da Mata. The mean scores for violence were significantly higher for less favorable outcomes, with the exception of suicide attempts in São Paulo. CONCLUSIONS: The instrument was shown to be adequate for estimating gender-based violence against women perpetrated by intimate partners and can be used in studies on this subject. It has high internal consistency and a capacity to discriminate between different forms of violence (psychological, physical and sexual) perpetrated in different social contexts. The instrument also characterizes the female victim and her relationship with the aggressor, thereby facilitating gender analysis.