Tenuous Links Between Late-Life Depression and Mortality

A higher risk of mortality in elderly patients with late-life depression may be related to older age, memory trouble, physical disabilities, and mirtazapine use, according to study results published in the Journal of Affective Disorders.

Using a register containing biomedical data from residents of southeast London in the United Kingdom, investigators identified patients >65 years old who were diagnosed with depressive disorder between January 2008 and December 2017. They followed these patients until death or through December 2017. The investigators looked at sociodemographic data, physical illness and disability comorbidity, depressive symptoms, and antidepressant and antipsychotic medication use to determine predictors of mortality.

The final cohort consisted of 4243 patients (mean age at time of depression diagnosis, 77.0±7.9 years; 61.2% women; 54.8% died during the study period; median follow-up time, 3.5 years). Across 3 multivariable Cox regression models, an elevated all-cause mortality risk was associated with moderate to severe impairment of activities of daily living (hazard ratio [HR], 2.02; P <.001), older age (HR, 1.04; P <.001), moderate to severe memory problems (HR, 1.34; P =.007), moderate to severe physical illness/disability (HR, 2.43; P <.001), apathy (HR, 1.33; P =.002), and mirtazapine use (HR, 1.51; P <.001). On the contrary, lower mortality risk was associated with female gender (HR, 0.56; P <.001), non-white ethnicity, feelings of guilt (HR, 0.79; P <.001), delusions (HR, 0.81; P =.037), tearfulness (HR, 0.86; P =.020), impaired concentration (HR, 0.80; P =.003), and disturbed sleep (HR, 0.72; P <.001).

The investigators found no consistent evidence of significant associations between mortality and depression severity; use of antidepressants or antipsychotics other than mirtazapine; or depressive symptoms such as helplessness, hopelessness, anhedonia, poor motivation, and agitation.

The investigators noted several limitations of their research, including a lack of data on cause-specific mortality and more general depressive symptoms, as well as reliance on a study population with more severe depressive disorders. The unexpected direction of associations between certain factors and mortality risk, as well as weak correlations, could be the result of the study not correcting for multiple comparisons. The researchers concluded by recommending that providers consider higher mortality risk factors in elderly patients with later-life depression and follow these patients more closely.

Reference

Cai W, Mueller C, Shetty H, Perera G, Stewart R. Predictors of mortality in people with late-life depression: a retrospective cohort study [published online January 10, 2020]. J Affect Disord. doi.org/10.1016/j.jad.2020.01.021