Cross-sectional epidemiologic studies have inconsistently reported associations between injuries and depressive symptoms. The significance of these findings remains unclear. Major depressive episodes (MDEs) may increase the risk of injury and injuries may increase the risk of MDEs. Longitudinal data are needed to distinguish between these possibilities.
Data from the Canadian National Population Health Survey (NPHS) were used in this analysis. The NPHS is a prospective study based on a representative sample of household residents in Canada. Injuries were evaluated using self-report items. MDE was assessed using the Composite International Diagnostic Interview-Short Form for major depression.
During each round of interviews, an association between MDE and injuries was evident. In longitudinal analyses a bidirectional association was found. MDEs increased the risk of injury (adjusted hazard ratio [HR] 1.6, 95% CI 1.3 to 2.0) and injury increased the risk of MDEs (adjusted HR 1.4, 95% CI 1.1 to 1.8).
Injury prevention efforts may benefit from consideration of MDE as an injury determinant. For example, particular occupational or recreational activities may have a higher risk of injury during depressive episodes. Improved access to mental health resources in clinical settings where injuries are treated may also be valuable. However, additional studies are necessary to confirm these observations and to develop evidence-based interventions.