Excess mortality of critically ill patients aged ≥90 years in intensive care units: A retrospective cohort study

The number of elderly patients (≥90 years) admitted to intensive care units (ICUs) is continuously increasing. Survival estimations that differentiate into population and excess mortality are lacking but might be warranted given the higher baseline mortality in this group.

We evaluated excess mortality and risk factors in 1076 ICU patients ≥90 treated at the University Medical Center Hamburg-Eppendorf, Germany, from 2008 to 2019 by relative survival analysis. The Human Mortality Database of the German population served as reference.

Population mortality - vulgo baseline mortality - accounted for 22.2 % of the observed 1-year mortality rate of 57.8 %. Within the tenth and eleventh decade of life, excess mortality was not significantly influenced by age - neither in ICU patients (HR 0.98 (0.94-1.03), p = 0.46) nor in ICU survivors (HR 0.96 (0.91-1.02), p = 0·15, each per year). Yet, SAPS-II, SOFA scores, dementia, aortic valve stenosis, myocardial infarction and other factors significantly influenced survival. The initial excess mortality rate was high after ICU admission (excess mortality risk λ=0.059 for all patients), but lower after ICU survival (λ=0.022). After around 100 days, the excess mortality risk had disappeared.

In the largest dataset analyzed to date, we were able show that age did not significantly affect excess mortality of ICU patients aged 90 years or older. With respect to the severity of their illness, excess mortality of patients aged 90 years and older in ICUs is within an adequate range. Briefly after patients have left the ICU alive, mortality equals that of the general population.