Healthcare utilization and mortality outcomes in patients with pre-existing psychiatric disorders after intensive care unit discharge
Creators: name: Rosgen, Brianna K
Publisher: name: Cumming School of Medicine
Year: 2021
Subjects: subject: Critical care
subject: psychiatry
subject: healthcare utilization
subject: mortality
subject: epidemiology
subject: cohort
subject: adult
subject: Health Sciences--Mental Health
subject: Health Sciences--Medicine and Surgery
subject: Health Sciences--Epidemiology

description: Critically ill patients commonly have comorbid psychiatric disorders upon admission to the intensive care unit (ICU). Psychiatric disorders may contribute to the complexity of critical illness, leading to worse outcomes. The work presented in this thesis estimated the association of pre-existing psychiatric disorders with subsequent healthcare utilization and mortality among critically ill adult patients up to three-years after discharge from ICU. We conducted a multicenter population-based retrospective cohort study of adults (&gt;=18 years) admitted to fourteen medical-surgical ICUs in Alberta, Canada between January 2014 and June 2016 with an ICU length of stay &gt;=24 hours, who survived to hospital discharge. The cohort was identified using eCritical, a provincial database of ICU admissions, linked to databases of hospital (Discharge Abstract Database), emergency department (National Ambulatory Care Reporting System), and outpatient (Physician Claims Database) encounters. Pre-existing psychiatric disorders (i.e., depression, anxiety, trauma- and stressor-related disorders, psychotic disorders, bipolar disorders, and substance use disorders) were identified using International Statistical Classification of Diseases and Related Health Problems, 9th and 10th Editions diagnostic codes captured in administrative databases up to five years before ICU admission. Outcomes were healthcare utilization (operationalized as any emergency department visit, hospital readmission, or ICU readmission) and mortality, evaluated at one-month, three-months, six-months, and annually up to three-years post-ICU discharge. We used logistic regression and Poisson regression models with inverse probability weighting to estimate Risk Ratios (RR) and Incidence Rate Ratios (IRRs). We included 10,598 patients, of whom 37.6% (n=3,982) had a pre-existing psychiatric disorder. Compared to patients without pre-existing psychiatric disorders, patients with pre-existing psychiatric disorders had a significantly higher risk of subsequent emergency department visits (one-year Risk Ratio [RR] 1.49, 95%CI 1.29-1.71), hospital readmission (one-year RR 1.49, 95%CI 1.34-1.66), and ICU readmission (one-year RR 2.64, 95%CI 1.55-4.49) post-ICU discharge. Patients with pre-existing psychiatric disorders had a significantly higher risk of mortality at six-months (RR 1.31, 95%CI 1.00-1.71) post-ICU discharge, compared to patients without pre-existing psychiatric disorders. The work presented in this thesis characterizes critically ill patients with pre-existing psychiatric disorders as a subpopulation vulnerable to increased healthcare utilization and mortality following ICU discharge and provides direction for future research.