Validity and reliability of the Brazilian version of the Work Ability Index - WAI: a re-evaluation.

The aim is to reevaluate the measurement properties of the Portuguese version of the Work Ability Index (WAI). A cross-sectional study was conducted with 3,051 nurses in the state of São Paulo. Participants answered a questionnaire on individual characteristics, working conditions, and WAI. Validity was assessed through discriminative analysis of known groups and exploratory factor analysis (EFA) with parallel analysis (PA). Reliability was assessed using Cronbach's alpha and McDonald's omega coefficients. In the analysis of known groups, all investigated individual and work variables showed statistically significant associations with WAI (p < 0.005). EFA revealed a unidimensional structure, which was confirmed by PA. The model proved to be appropriate (root mean square error of approximation = 0.125; Tucker-Lewis Index = 0.900), although the Comparative Fit Index = 0.882 was slightly lower than expected. Reliability was satisfactory (Cronbach's alpha coefficient = 0.787 and McDonald's omega = 0.819). The WAI continues to be a valid and reliable measure to evaluate work ability in the current context of Brazilian work.