Purpose To examine the effects of preexisting comorbid psychiatric conditions on mortality in a large cohort of patients admitted to a nonsurgical intensive care unit.
Methods This retrospective cohort study involved 66 672 consecutive eligible nonsurgical patients admitted to intensive care units in 129 Veterans Health Administration hospitals during 2005 and 2006. Preexisting comorbid psychiatric conditions were identified by using diagnoses from outpatient encounters in the prior year for depression, anxiety, psychosis, bipolar disorders, and posttraumatic stress disorder. Generalized estimating equations were used to adjust the risks of inhospital and 30-day mortality for demographics, comorbid medical conditions, markers of severity, and abnormal findings on laboratory tests at admission.
Results Comorbid psychiatric conditions were identified in 28% (n = 18 698) of patients. Patients with preexisting comorbid psychiatric conditions had lower (P < .001) unadjusted inhospital mortality (7.3% vs 8.7%) and 30-day mortality (10.0% vs 12.8%) than did patients without such conditions. After demographics, comorbid medical conditions, and severity were adjusted for, risk of in-hospital mortality among patients with comorbid psychiatric conditions was somewhat higher (odds ratio, 1.07, 95% confidence interval, 1.01–1.14; P = .02), although differences in 30-day mortality (odds ratio, 1.01, 95% confidence interval, 0.94–1.08; P = .70) were no longer significant.
Conclusion Preexisting comorbid psychiatric conditions are common among intensive care patients, but after comorbid medical conditions and severity were adjusted for, preexisting comorbid psychiatric conditions were not associated with a higher risk of 30-day mortality in a large national cohort of veterans.