The validity and reliability of the Persian version Work Ability Index and its relationship with physical fitness indicators among employees in Kermanshah

The aim of this study was to evaluate the validity and reliability of the Persian version work ability index and its relationship with the physical fitness indicators among employees in Kermanshah in 868 (250 females, 618 males) were selected through multi-stage sampling method. The research instrument consisted of questionnaire and physical fitness tests. Questionnaire validity was determined via content validity, convergent and divergent validity and exploratory factor analysis and confirmatory factor analysis were utilized to test the factor structure. Internal consistency was determined Cronbach’s alpha. Finally, the data were analyzed using Pearson correlation coefficient and simultaneous regression model
The principal component analysis with varimax rotation identified two factors subjective health related work ability) 41.86% of the variance) and ill- health related work ability (19.47% of the variance) in the index construct. Results convergent validity showed high correlation between questions of ability to work, and intraclass coefficient correlation 0.72-0.81 also was high. Mean WAI index score was higher among employees with low absenteeism (40.46 points) than among those with high absenteeism (32.04 points). Reliability of the index with Cronbach’s alpha 0.74 was acceptable. Goodness-of-fit indices of second-order factor analysis confirmed the tow extracted factors and two-factor model had a superior fit compared to the one-dimensional model. Finally multiple linear regression showed physical fitness tests were predictor factors for the work ability among employees. In conclusion, Persian version of the Work Ability Index showed satisfactory psychometric properties among employees.