VANCOUVER, B.C. – Age was independently associated with mortality in patients admitted to the ICU with pneumonia.
Overall mortality was 17% at 30 days and 32% at 1 year in a prospective, population-based cohort study involving 351 ICU patients. After adjustment for pneumonia severity, comorbid disease, sex, smoking status, alcohol use, and other potential confounders, each 10-year increase in age was associated with a 24% increase in 30-day mortality and a 39% increase in 1-year mortality, Dr. Wendy I. Sligl said at the annual meeting of the Infectious Diseases Society of America.
"This is a very high mortality rate, with almost one-third of patients dead at 1 year," said Dr. Sligl of the University of Alberta, Edmonton. Long-term mortality in these patients may rival or exceed that seen in patients with heart failure or end-stage renal disease.
"We tend to think of community-acquired pneumonia as a reversible problem. Patients come in, they get treated for their pneumonia, they come off the ventilator, they go home, and they’re fixed. And that really is not what we’re seeing with this data," she said.
Dr. Sligl and her fellow researchers enrolled all adults aged 17 years and older who were hospitalized with pneumonia in one of the six hospitals and five ICUs in Edmonton. The study excluded patients who were pregnant or lactating, had been previously hospitalized within 30 days, or were immunosuppressed. Of 3,415 patients admitted with pneumonia between 2000 and 2002, 351 were admitted to the ICU within 24 hours of their presentation at the emergency department.
The mean age of the 351 ICU patients was 61 years, with 43% younger than 60, 18% between 60 and 69, 23% between 70 and 79, and 15% aged 80 years and older (percentages do not total to 100% due to rounding). Most (59%) were male.
After adjustment for functional impairment, number of comorbidities, and illness severity in their multivariate analysis, the researchers found several independent predictors of mortality besides age. Patients with a living will had a threefold increase in 30-day mortality and a twofold increase in 1-year mortality. Every 10 points on the modified Pneumonia Severity Index increased the risk of 30-day mortality by 11% and the risk of 1-year mortality by 12%.
Dr. Sligl advanced several possible explanations for the independent relationship between age and mortality. Elderly patients may be frailer or have decreased reserve, she said. "This is very difficult to measure objectively and to include in multivariable modeling. There are many physiologic changes associated with aging that can predispose [a person to] the development of pneumonia and the severity of disease including decreased lung compliance, decreased respiratory muscle strength, retained secretions, ... and dysfunctional and impaired immunity."
Dr. Sligl said that she and her colleagues had no relevant financial disclosures.