Mortality in intensive care patients with respiratory disease. Is age important?

Age has been proposed as a criterion for health care rationing. However, the relationship of age and other prognostic factors to in-hospital mortality in older patients is unclear. The purpose of this study was to examine the effect of age on hospital mortality for patients admitted to the intensive care unit.

This historical prospective study examined 3050 admissions of patients aged 50 years and older with disease of the lower respiratory tract to intensive care units in 78 hospitals in the United States during an 18-month period (July 1987 through December 1988). The association of age with hospital mortality was examined by means of a multiple logistic regression model that included age, gender, primary discharge diagnosis, severity, and comorbid diseases.

Variables significantly predictive of in-hospital mortality included age, severity of illness, diagnosis, and a history of chronic obstructive pulmonary disease. In contrast, gender, diabetes mellitus, congestive heart failure, angina, and stroke/transient ischemic attack were not significant predictors of mortality. Predicted mortalities varied from 0.7% to 40.7% in 50-year-old patients and from 5.5% to 78.6% in 90-year-old patients.

Chronological age is independently associated with in-hospital mortality in patients with disease of the lower respiratory tract admitted to an intensive care unit. However, the clinical importance of this relationship is modulated by other variables, such as the primary diagnosis, the presence of comorbid conditions (chronic obstructive pulmonary disease), and the severity of the acute illness, such that use of age alone is not sufficient to predict hospital outcome.