Exploratory study of the validity and internal consistency of the Work Ability Index among health workers

The objective of this study was to evaluate the validity and internal consistency of the Work Ability Index (WAI) among health workers in Bahia, Brazil. An exploratory validity study was conducted based on a cross-sectional sample of 3,084 health workers. The principal component analysis extracted three factors of the instrument with a total accumulated variance of 53.9%. The WAI was able to identify groups of workers by age and show positive correlations with job control, social support and self-perceived health status as well as negative correlations with common mental disorders, psychological, physical and emotional demand and the effort-reward imbalance. The Cronbach's alpha underestimated the coefficients of each factor compared to McDonald's omega. The WAI showed satisfactory psychometric properties to measure physical and mental work ability in groups of workers according to age.