The association between depression and mortality - a comparison of survey- and register-based measures of depression

- The association between different measures of depression and mortality was examined.
- Register- and survey-based depression measures were obtained for the same population.
- Depression was associated with mortality independently of the type of measure.
- The association was of a similar magnitude for register- and survey based measures.

BackgroundA number of studies have associated depression with a high mortality risk. However, in surveys, depression is often measured by self-reports in selected sub-samples, while register studies have been based on hospital diagnosis or purchase of antidepressants. We examined how different survey- and register-based measures of depression were associated with 7-year mortality in a cohort of middle-aged Danish men.MethodsThe study was based on 10,517 men born in 1953. Depression was assessed through hospital diagnosis for the period from 1969 to 2004 and by self-reported information on depression, use of antidepressants and the Major Depression Inventory (MDI) from a survey in 2004, in which 58.8% (n=6292) of the men participated. Information on mortality and cause of death was retrieved from registers for the period between 2004 and 2011.ResultsDepression diagnosis from hospital registers as well as self-reported depression, use of antidepressants and having a high MDI-score were significantly associated with mortality from all, natural and unnatural causes. The associations were of a similar magnitude for the register-based measure of depression and for the survey-based measures reflecting past depression, but the strongest association was found for current depression as assessed by the MDI-score.LimitationsThe study population consists almost exclusively of white men and the findings may not be generalizable to female populations or other races and ethnicities.ConclusionsPhysicians should be aware of male patients with a history of depression from hospital records or self-reported as they have higher mortality risk years after their first symptom.