Antidepressant treatment and mortality in people with comorbid depression and type 2 diabetes: UK electronic health record study.

BACKGROUND: Depression is associated with higher rates of premature mortality in people with physical comorbidities, such as type 2 diabetes. Conceptually, the successful treatment of depression in people with type 2 diabetes could prevent premature mortality.

AIMS: To investigate the association between antidepressant prescribing and the rates of all-cause and cause-specific (endocrine, cardiovascular, respiratory, cancer, unnatural) mortality in individuals with comorbid depression and type 2 diabetes.

METHOD: Using UK primary care records between years 2000 and 2018, we completed a nested case-control study in a cohort of people with comorbid depression and type 2 diabetes who were starting oral antidiabetic treatment for the first time. We used incident density sampling to identify cases who died and matched controls who remained alive after the same number of days observation. We estimated incidence rate ratios for the association between antidepressant prescribing and mortality, adjusting for demographic characteristics, comorbidities, medication use and health behaviours.

RESULTS: We included 5222 cases with a recorded date of death, and 18 675 controls, observed for a median of 7 years. Increased rates of all-cause mortality were associated with any antidepressant prescribing during the observation period (incidence rate ratio 2.77, 95% CI 2.48-3.10). These results were consistent across all causes of mortality that we investigated.

CONCLUSIONS: Antidepressant prescribing was highly associated with higher rates of mortality. However, we suspect that this is not a direct causal effect, but that antidepressant treatment is a marker of more severe and unsuccessfully treated depression.