Objective  

To determine the threshold of age that best discriminates the survival of mechanically ventilated patients and to estimate the outcome of mechanically ventilated older patients.

Design  

International prospective cohort study.

Setting  

Three hundred sixty-one intensive care units from 20 countries.

Patients and participants  

Five thousand one hundred eighty-three patients mechanically ventilated for more than 12 h.

Interventions  

None.

Measurements and results  

Recursive partitioning and logistic regression were used and an outcome model was derived and validated using independent subgroups of the cohort. Two age thresholds (43 and 70 years) were found, by partitioning recursive analysis, to be associated with outcome. This study focuses on the analysis of patients older than 43 years of age, divided in two subgroups: between 43 and 70 years (middle age group) and older than 70 years (elderly group). Survival in hospital was 45% (95% C.I.: 43–48) for the elderly group and 55% (53–57) for the middle age group (p<0.001). Advanced age was not associated with prolongation of mechanical ventilation, weaning or length of stay in the ICU and in hospital (p>0.05). Variables associated with mortality in the elderly were: acute renal failure, shock, Simplified Acute Physiology Score II and a ratio of PaO₂ to FIO₂ more than 150.

Conclusions  

Older mechanically ventilated patients (age >70 years) had a lower ICU and hospital survival, but the duration of mechanical ventilation, ICU and hospital stay were similar to younger patients. Factors associated with the highest risk of mortality in patients older than 70 were the development of complications during the course of mechanical ventilation, such as acute renal failure and shock.