Background: Burnout has been presented as an antecedent of depression, but longitudinal data are lacking. We investigated whether burnout mediates the association between job strain and depressive symptoms.
Methods: Two surveys were conducted. In 2003, 71% of Finnish dentists were reached, and the response rate of the 3-year follow-up was 84% (n=2555). Burnout was measured with the Maslach Burnout Inventory and depressive symptoms with the Beck Depression Inventory. The sequences 'job strain-burnout-depressive symptoms' and 'job strain-depressive symptoms-burnout' were investigated with logistic regression analyses.
Results: Of the burnout sufferers without depressive symptoms at baseline, 23% reported depressive symptoms at follow-up. The adjusted odds ratio of burnout for depressive symptoms was 2.6 (95% CI 2.0-3.5). The effect of job strain on depressive symptoms had an OR of 3.4 (95% CI 2.0-5.7), but it disappeared when adjusted for burnout. Of those who had depressive symptoms without burnout at baseline, 63% had burnout at follow-up. The adjusted odds ratio of depressive symptoms for burnout was 2.2 (95% CI 1.4-3.4). The effect of job strain on burnout had an OR of 27.9 (95% CI 6.5-120.2) for the men and 4.9 (95% CI 2.5-9.6) for the women. These effects remained significant after adjustment for depressive symptoms.
Limitations: The study was conducted among one occupational group.
Conclusions: There is a reciprocal relationship between burnout and depressive symptoms. Job strain predisposes to depression through burnout. In comparison, job strain predisposes to burnout directly and via depression.