Mortality in elderly ICU patients: a cohort study.

Abstract

The population is aging. We examined changes in the proportion of elderly (≥ 80 years) intensive care unit (ICU) patients during 2005-2011 and the association between age and mortality controlling for preexisting morbidity. Through the Danish National Patient Registry, we identified a cohort of 49,938 ICU admissions (47,596 patients) in Northern Denmark from 2005 to 2011. Patients were subdivided in age groups (15-49, 50-64, 65-79 and ≥ 80 years) and calendar year. We estimated 30-day and 31-365-day mortality and mortality rate ratios (MRRs), stratified by admission type (medical and elective/acute surgical patients). Mortality was compared between age groups adjusting for sex and preexisting morbidity using 50-64-year-olds as reference. The proportion of elderly patients increased from 11.7% of all ICU patients in 2005 to 13.8% in 2011. Among the elderly, the 30-day mortality was 43.7% in medical, 39.6% in acute surgical, and 11.6% in elective surgical ICU patients. The corresponding adjusted 30-day MRRs compared with the 50-64-year-olds were 2.7 [95% confidence interval (CI) 2.5-3.0] in medical, 2.7 (95% CI 2.4-3.0) in acute surgical, and 5.2 (95% CI 4.1-6.6) in elective surgical ICU patients. The 31-365-day mortality among elderly patients was 25.4% in medical, 26.9% in acute, and 11.9% in elective surgical ICU patients, corresponding to adjusted MRRs of 2.5 (95% CI 2.1-2.9), 2.2 (95% CI 1.9-2.5), and 1.9 (95% CI 1.6-2.3), respectively. During 2005-2011, there was an 18% increase in the proportion of elderly ICU patients. Advancing age is associated with increased mortality even after controlling for preexisting morbidity.