The longitudinal joint effect of obesity and major depression on work performance impairment

Objectives: We examined the longitudinal effect of obesity, major depression, and their combination on work performance impairment (WPI). Methods: We collected longitudinal data (2004-2013) on 1726 paid employees from the Netherlands Study of Depression and Anxiety at baseline and 2-, 4-, and 6-year follow-up. We defined obesity with body mass index and waist circumference. We diagnosed major depression with the Composite International Diagnostic Interview 2.1. We assessed work performance impairment with a questionnaire for illness-associated costs. We used generalized estimating equations for modeling, and estimated interaction on the additive scale. Results: Obesity, abdominal obesity, and major depression were longitudinally associated with increased risk of high WPI. The combinations of obesity and major depression, and of abdominal obesity and major depression were associated with increased risk of high WPI (odds ratios of 2.36 [95% confidence interval=1.61, 3.44] and 1.88 [95% confidence interval =1.40, 2.53], respectively), but the relative excess risks attributable to interaction were nonsignificant. Conclusions: The longitudinal joint effect of obesity and major depression on high WPI implies that obesity intervention may be more beneficial for individuals with major depression than those without regarding risk of high WPI, if confirmed in a large, representative sample.