Optimism and pessimism as predictors of work disability with a diagnosis of depression: a prospective cohort study of onset and recovery.

BACKGROUND

Personality characteristics are assumed to affect to the vulnerability to depression and its outcomes. The aim of this study was to examine optimism and pessimism as predictors of depression-related work disability and subsequent return to work.

METHODS

We conducted a prospective cohort study of 38,214 public sector employees with no record of diagnosed depression. Optimism and pessimism were measured using the Revised Life Orientation Test (LOT-R). Records of long-term (>90 days) work disability with a diagnosis of depression and subsequent return to work until the end of 2005 were obtained from the national health registers.

RESULTS

During the mean follow-up of 4.0 (SD=2.3) years, 287 employees encountered work disability with a diagnosis of depression. Of them, 164 (57%) returned to work during the follow-up. One unit increase in the optimism mean score (range 1-4) was associated with a 25% lower risk of work disability due to depression and a 37% higher probability of returning to work after a work disability period when adjusted for age and sex. In the fully-adjusted model hazard ratios per one unit increase in optimism were 0.79 (95% CI 0.66-0.96) for work disability and 1.30 (95% CI 1.01-1.66) for return to work. The pessimism mean score (range 1-4) was only associated with a lower probability of returning to work (fully-adjusted HR per one unit increase 0.66, 95% Cl 0.49-0.88).

CONCLUSION

The level of optimism was a stronger predictor of work disability with a diagnosis of depression than the level of pessimism, while both optimism and pessimism predicted returning to work.