Objective: To study BMI and change in BMI from age 25 as predictors of sickness absence.
Research methods and procedures: Data were collected from 2564 women and 5853 men, who were British civil servants (35 to 55 years) on entry to the Whitehall II study (Phase 1, 1985 to 1988). Employer's records provided annual medically certified (long, >7 days) and self-certified (short, 1 to 7 days) spells of sickness absence. BMI at age 25 and Phase 1 were examined in relation to absences from Phase 1 to the end of 1998 (mean follow-up, 7.0 years).
Results: After adjustment for employment grade, health-related behaviors, and health status, overweight (BMI = 25.0 to 29.9 kg/m(2)) and obesity (BMI > 30.0 kg/m(2)) at Phase 1 were significant predictors of short and long absences in both sexes; rate ratios (95% confidence intervals) ranged from 1.13 (1.05 to 1.21) to 1.51 (1.30 to 1.76) compared with a BMI of 21.0 to 22.9 kg/m(2). Additionally, a BMI of 23.0 to 24.9 kg/m(2) at Phase 1 predicted long absences in women, and underweight (BMI < 21.0 kg/m(2)) predicted short absences in men. Obesity at age 25 predicted long absences, and obesity at Phase 1 predicted short and long absences in both sexes. Chronic obesity was a particularly strong predictor of long absences in men, with a rate ratio of 2.61 (1.88 to 3.63).
Discussion: Findings from this well-characterized cohort suggest that the obesity epidemic in industrialized countries may result in significant increases in sickness absence. Further research is needed to determine the underlying mechanisms. Policy to reduce sickness absence needs to tackle the problem of excess weight in the working population.