Depression or anxiety and long-term mortality among adult survivors of intensive care unit: a population-based cohort study

Abstract

Background: Many patients who survive intensive care unit (ICU) stays experience persistent mental impairments. It is estimated that one-third of ICU survivors suffer from psychiatric disorders. However, research into how these disorders affect long-term outcomes in this population is scarce. Therefore, the aim of this study is to investigate the association between depression or anxiety and long-term mortality among ICU survivors. Methods: This population-based cohort study included patients admitted to the ICU between January 1, 2015 and December 31, 2019, who survived at least 1 year after ICU discharge. Exclusions were made for patients admitted for non-medical reasons and those who had been in the ICU in the previous 2 years, and 799,645 patients were included in the study. Follow-up data were obtained for up to 7 years. The primary outcome was long-term cumulative mortality. Mortality rates for patients with and without diagnoses of depression or anxiety were compared. Results: Of the 799,645 adult ICU survivors, 98,530 (12.3%) were newly diagnosed with depression or anxiety post-discharge, and 265,092 (33.2%) had been diagnosed prior to ICU admission. Multivariate Cox proportional hazards regression analysis revealed that the adjusted hazard ratio (HR) for long-term mortality was 1.17 (95% CI, 1.16-1.19) for those newly diagnosed with depression or anxiety, 1.28 (95% CI, 1.26-1.30) for depression alone, and 1.08 (95% CI, 1.06-1.11) for anxiety alone. For those with prior diagnoses, the adjusted HR was 1.08 (95% CI, 1.07-1.09) overall, 1.12 (95% CI, 1.11-1.14) for depression, and 1.04 (95% CI, 1.03-1.05) for anxiety. Conclusions: ICU survivors newly diagnosed with depression or anxiety exhibit higher long-term mortality rates compared to those without such diagnoses, including those diagnosed before ICU admission. Particularly, newly diagnosed depression is associated with an elevated mortality rate. These findings underscore the need for psychological interventions to enhance long-term survival among ICU survivors.