Background: Based on the current literature, it is unclear whether advanced age itself leads to higher mortality in critically ill patients or whether it is due to the greater number of comorbidities in the elderly patients. We hypothesized that increasing age would increase the odds of short-term and long-term mortality after adjusting for baseline comorbidities in intensive care unit (ICU) patients.
Methods: We performed a retrospective cohort study of 57 160 adults admitted to any ICU over 5 years at 2 academic tertiary care centers. Patients were divided into age-groups, 18 to 39, 40 to 59, 60 to 79, and ≥80. The primary outcomes were 30-day and 365-day mortality. Results were analyzed with multivariate logistic regression adjusting for demographics and the Elixhauser-van Walraven Comorbidity Index.
Results: The adjusted 30-day mortality odds ratios (ORs) were 1.39 (95% confidence interval [CI]: 1.21-1.60), 2.00 (95% CI: 1.75-2.28), and 3.33 (95% CI: 2.90-3.82) for age-groups 40 to 59, 60 to 79, and ≥80, respectively, using the age-group 18 to 39 as the reference. The adjusted 365-day mortality ORs were 1.46 (95% CI: 1.32-1.61), 2.10 (95% CI: 1.91-2.31), and 2.96 (95% CI: 2.67-3.27).
Conclusion: In critically ill patients, increasing age is associated with higher odds of short-term and long-term death after correcting for existing comorbidities.
Keywords: age; comorbidity index; elderly; intensive care unit; mortality.