Healthcare utilization and mortality outcomes in patients with pre-existing psychiatric disorders after intensive care unit discharge: A population-based retrospective cohort study.

Abstract Purpose Pre-existing psychiatric disorders may lead to negative outcomes following intensive care unit (ICU) discharge. We evaluated the association of pre-existing psychiatric disorders with subsequent healthcare utilization and mortality in patients discharged from ICU. Materials and methods We retrospectively studied adult patients admitted to 14 medical-surgical ICUs (January 2014–June 2016) with ICU length stay ≥24 h who survived to hospital discharge. Pre-existing psychiatric disorders were identified using algorithms for diagnostic codes captured ≤5 years before ICU admission. Outcomes were healthcare utilization (emergency department visit, hospital or ICU readmission) and mortality. We used logistic regression models with propensity scores to estimate associations, converted to risk ratios (RR). Results We included 10,598 patients. 37.6% (n = 3982) had a psychiatric history. Patients with pre-existing psychiatric disorders were at higher risk of subsequent emergency department visits (RR 1.49, 95%CI 1.29–1.71), hospital readmission (RR 1.49, 95%CI 1.34–1.66), ICU readmission (RR 2.64, 95%CI 1.55–4.49) one-year post-ICU discharge, compared to patients without pre-existing psychiatric disorders. Patients with pre-existing psychiatric disorders had a higher risk of mortality (RR 1.31, 95%CI 1.00–1.71) six-months post-ICU discharge. Conclusion Critically ill patients with pre-existing psychiatric disorders have an increased risk of healthcare utilization and mortality outcomes following an ICU stay.