Decrease in Work Ability Index and sickness absence during the following year: a two-year follow-up study

Using a 2-year follow-up design, we examined whether changes in work ability during 1 year predicted sickness absence in the following year.

Workers (N = 1408) from the Japanese information technology sector each completed the Work Ability Index (WAI), the Brief Job Stress Questionnaire (BJSQ), and the General Health Questionnaire (GHQ) in 2011 and 2012. Absence data during 2013 was obtained from employees' computerized attendance records. We used psychological distress as evaluated by the GHQ; job stress and job support calculated using the BJSQ; and job title, sex, and age as potential confounding variables.

Thirty-five employees had at least one sickness absence lasting more than seven consecutive days in 2013. Forty-nine percent of sickness absences were due to mental illness, and the others were due to orthopedic disease (20%), cancer (9%), and other illnesses (23%). Decrease in WAI scores from 2011 to 2012 predicted sickness absence in 2013 (Odds ratio (OR) 1.19, 95% confidence interval (CI) 1.12-1.27). This association remained unaltered after adjusting for sex, age, job title, WAI score from the year before, job stress, job support, and GHQ score (OR 1.15, 95% CI 1.06-1.25). We analyzed this association separately by reason for absence: mental or other illness. WAI score decreases predicted sickness absence for both reasons (OR for mental illness 1.24, 95% CI 1.14-1.36; OR for other illnesses 1.14, 95% CI 1.04-1.24).

Decrease in work ability during the year predicts sickness absence in the following year while predictive power was weak.