Baseline Anxiety and Depression and Risk for ICU Delirium: A Prospective Cohort Study

OBJECTIVES: Anxiety and depression are common mental disorders in adults admitted to the ICU. Although depression increases postsurgical delirium and anxiety does not, their associations with ICU delirium in critically ill adults remain unclear. We evaluated the association between ICU baseline anxiety and depression and ICU delirium occurrence. DESIGN: Subgroup analysis of a prospective cohort study. SETTING: Single, 36-bed mixed ICU. PATIENTS: Nine-hundred ninety-one ICU patients admitted with or without delirium between July 2016 and February 2020; patients admitted after elective surgery or not assessed for anxiety/depression were excluded. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The Hospital Anxiety and Depression Scale questionnaire was administered at ICU admission to determine baseline anxiety and depression. All patients were assessed with the Confusion Assessment Method for the ICU (CAM-ICU) q8h; greater than or equal to 1 +CAM-ICU assessment and/or scheduled antipsychotic use represented a delirium day. Multivariable logistic and Quasi-Poisson regression models, adjusted for ICU days and nine delirium risk variables (“Pre-ICU”: age, Charlson Comorbidity Index, cognitive impairment; “ICU baseline”: Acute Physiology and Chronic Health Evaluation-IV, admission type; “Daily ICU”: opioid and/or benzodiazepine use, Sequential Organ Failure Assessment score, coma), were used to evaluate associations between baseline anxiety and/or depression and ICU delirium. Among the 991 patients, 145 (14.6%) had both anxiety and depression, 78 (7.9%) had anxiety only, 91 (9.2%) had depression only, and 677 (68.3%) had neither. Delirium occurred in 406 of 991 total cohort (41.0%) patients; in the baseline anxiety and depression group, it occurred in 78 of 145 (53.8%), in the anxiety only group, 37 of 78 (47.4%), in the depression only group, 39 of 91 (42.9%), and in the group with neither in 252 of 677 (37.2%). Presence of both baseline anxiety and depression was associated with greater delirium occurrence (adjusted odds ratio, 1.99; 95% CI, 1.10–3.53; p = 0.02) and duration (adjusted risk ratio, 1.62; 95% CI, 1.17–2.23; p < 0.01). CONCLUSIONS: Baseline anxiety and depression are associated with increased ICU delirium occurrence and should be considered when delirium risk reduction strategies are being formulated.