Mechanical Ventilation in a Cohort of Elderly Patients Admitted to an Intensive Care Unit

Abstract

Background: It has been argued that life support for the elderly should be limited to conserve resources. As this population increases, so will the importance of evaluating appropriate use of mechanical ventilation in this group.

Objective: To determine whether age has an independent effect on the outcomes of patients treated with mechanical ventilation after admission to an intensive care unit (ICU).

Design: Prospective cohort study.

Setting: University-based tertiary care medical center.

Patients: 63 patients 75 years of age or older and 237 patients younger than 75 years of age enrolled from medical and coronary ICUs.

Measurements: In-hospital mortality rate, duration of mechanical ventilation, lengths of stay in the ICU and in the hospital, and cost of care.

Results: Median duration of mechanical ventilation was 4.2 days (interquartile range, 2.1 to 9.3 days) for patients 75 years of age or older and 6.4 days (interquartile range, 3.4 to 11.4 days) for patients younger than 75 years of age (P = 0.14). When the length of time required to “pass” a daily screening test of weaning variables was used as an indicator of recovery from respiratory failure, elderly patients passed earlier than younger patients (risk ratio, 1.58 [95% CI, 1.13 to 2.22]; P = 0.03). The cost of ICU care was lower for older ($12 822 [CI, $9821 to $26 313] than for younger ($19 316 [CI, $9699 to $39 950]) patients (P = 0.03). Median hospital costs tended to be lower in the older group ($21 292 compared with $29 049; P = 0.17). After adjustment for ethnicity, sex, and severity of illness in a multivariate logistic regression analysis, patient age of 75 years or older was predictive of 1 less day on the ventilator (CI, −2.8 to 1.2 days). Lengths of stay in the ICU (β-coefficient, −0.5 days [CI, −3.0 to 2.7 days]) and in the hospital (β-coefficient, 0.3 days [CI, −3.7 to 5.5 days]) did not differ for persons 75 years of age or older after these adjustments (P > 0.1). Intensive care unit and hospital costs, however, were lower for elderly persons (P = 0.02). The in-hospital mortality rate was 38.1% among elderly patients and 38.8% among younger patients (P > 0.2); Cox proportional-hazards analysis confirmed that survival did not differ between the two groups (relative risk for older patients, 0.82 [CI, 0.52 to 1.29]).

Conclusions: After adjustment for severity of illness, elderly patients spent similar time on mechanical ventilation and in the ICU and hospital but had a lower cost of care than younger patients. These outcomes are not explained by differences in mortality rate and suggest that mechanical ventilation should not be restricted in elderly patients with respiratory failure on the basis of chronologic age.