Comparison of Mortality Risk Prediction Among Patients ≥70 Versus <70 Years of Age in a Cardiac Intensive Care Unit

Abstract

Older adults account for an increasing number of cardiac intensive care unit (CICU) admissions. This study sought to determine the predictive value of illness severity scores for mortality in CICU patients ≥70 years of age. Adult patients admitted to the CICU from 2007 to 2015 at one tertiary care hospital were reviewed. Severity of illness scores were calculated on the first CICU day. Area under the receiver-operator characteristic curve (AUROC) values were used to assess discrimination for hospital mortality in patients ≥70 versus <70 years of age. We included 10,004 patients with a mean age of 67.4 ± 15.2 years (37.4% female); 4,771 patients (47.7%) were ≥70 years of age. Patients ≥70 years of age had greater illness severity and more extensive co-morbidities compared with patients <70 years of age. Patients ≥70 years of age had higher hospital mortality (11.6% vs 6.8%, odds ratio 1.80, 95% confidence interval 1.57 to 2.07, p <0.001), with a progressive increase in mortality as a function of decade. Severity of illness scores had lower AUROC values for hospital mortality in patients ≥70 years of age compared with patients <70 years of age (all p <0.05 by DeLong test). The Braden skin score on CICU admission predicted hospital mortality with an AUROC value only slightly lower than these scores. Increasing age decade was associated with decreased postdischarge survival by Kaplan-Meier analysis (p <0.001 by log-rank). In conclusion, contemporary CICU patients ≥70 years of age have greater illness severity, more co-morbidities and higher mortality than patients <70 years of age, yet severity of illness scores are less accurate for predicting mortality in CICU patients ≥70 years of age, emphasizing the need for more effective risk-stratification methods in this population.