Age still matters: prognosticating short- and long-term mortality for critically ill patients with pneumonia

Abstract

Objective: To determine the association between age and mortality in critically ill patients with pneumonia. We hypothesized that increasing age would be independently associated with both short- and long-term mortality.

Design: Prospective population-based cohort study examining the association between age and 30-day (short-term) and 1-yr (long-term) mortality using Cox proportional hazards regression, adjusting for pneumonia severity, mechanical ventilation, sex, functional status, nursing home residence, and having a living will.

Setting: Five intensive care units in Edmonton, Alberta, Canada.

Patients: Critically ill adult patients with pneumonia.

Measurements and main results: The cohort included 351 intensive care unit patients; mean age 61 yrs, 59% male, 16% from nursing homes. Mean Pneumonia Severity Index was 115 (73% Pneumonia Severity Index class IV or V), mean Acute Physiology and Chronic Health Evaluation II score 17, and 83% received invasive mechanical ventilation. Overall, 151 (43%) were < 60 yrs old, 64 (18%) were 60-69 yrs old, 82 (23%) were 70-79 yrs old, and 54 (15%) were ≥ 80 yrs old. By 30 days, 58 of 351 (17%) had died; by 1 yr, 112 of 351 (32%) had died. Mortality increased with age, 28 of 151 (19%) in those < 60 yrs, 14 of 64 (22%) in those 60-69 yrs, 39 of 82 (48%) in those 70-79 yrs, and 31 of 54 (57%) in those ≥ 80 yrs. Independent of pneumonia severity and other factors, age (per 10-yr increase) was associated with 30-day mortality (adjusted hazard ratio 1.24, 95% confidence interval 1.03-1.49, p = .026) and 1-yr mortality (adjusted hazard ratio 1.39, 95% confidence interval 1.21-1.60, p < .001). Having a living will was similarly associated with increased mortality (adjusted hazard ratio 3.08, 95% confidence interval 1.61-5.90, p < .001 at 30 days; adjusted hazard ratio 2.00, 95% confidence interval 1.21-3.32, p = .007 at 1 yr).

Conclusions: Increasing age was independently associated with risk-adjusted short- and long-term mortality in critically ill patients with pneumonia. These findings may help elderly patients, their families, and physicians better understand what intensive care unit admission can offer and help them to make more informed decisions.