Objective: To examine the relationship between age and mortality in ARDS patients and evaluate the importance of factors that increase the mortality of older ARDS patients.
Design: Prospective inception cohort study.
Setting: Community-based referral hospital.
Patients: Two hundred fifty-six ARDS patients identified from May 1987 to December 1990. ARDS was defined by the following: (1) PaO2/PAO2≤0.2; (2) pulmonary capillary wedge pressure ≤15 mm Hg; (3) total static thoracic compliance ≤50 mL/cm H2O; (4) bilateral infiltrates on chest radiograph; and (5) an appropriate clinical setting for ARDS.
Main outcome measures: Comparison of organ failure, incidence of sepsis, patient demographics, arterial oxygenation, and level of support in those 55 years and younger and those older than 55 years of age. Withdrawal of support in patients who died.
Results: Seventy-two of 112 patients older than 55 years (64%) died vs 65 of 144 patients 55 years and younger (45%) (p=0.002). Examination of patient groups using age identified older than 55 years as a "cutpoint" above which mortality was greater (p=0.002). Older nonsurvivors did not differ from nonsurvivors 55 years or younger with respect to gender, smoking history, ARDS risk factors, ARDS identifying characteristics, APACHE II (acute physiology and chronic health evaluation), number of organ failures, or the incidence of sepsis. In the 48 h prior to death, nonsurvivors 55 years and younger had more organ failure (3.4±0.2 vs 2.8±0.2; p=0.03), higher fraction of inspired oxygen (0.82±0.03 vs 0.68±0.03; p=0.008), and higher positive end-expiratory pressure levels (13±1 vs 8±1; p=0.001) than older nonsurvivors. Despite more severe expression of disease, only 32 (50%) nonsurvivors 55 years and younger had support withdrawn. Significantly more nonsurvivors older than 55 years (73%) had support withdrawn (p=0.009). Even in the absence of chronic disease states, withdrawal was more likely for patients older than 55 years (21/51) than in those 55 years and younger (3/32; p<0.001).
Conclusions: Mortality is significantly higher for patients with ARDS older than 55 years. Decisions to withdraw support are made more often in ARDS patients older than 55 years. These data suggest that age bias may influence decisions to withdraw support.