Pneumonia in long-term care: a prospective case-control study of risk factors and impact on survival

Abstract

Background: Pneumonia is a major cause of morbidity and mortality in long-term care facilities. Prior studies of pneumonia have failed to identify risk factors potentially amenable to intervention. Our objectives were to (1) identify modifiable risk factors for the occurrence of pneumonia and (2) determine the long-term impact of pneumonia on survival.

Methods: We performed a case-control study among residents of a Veterans Affairs long-term care facility. Case patients included all patients developing pneumonia from 2 days to 1 year after admission. Control subjects were matched for admission date, level of nursing care, and dependence in activities of daily living. Patients were followed up for 2 years or until death or discharge from the facility.

Results: We identified 104 case-control pairs. Risk factors significantly associated with pneumonia included witnessed aspiration (odds ratio, 13.9; 95% confidence interval, 1.7-111.0; P =.01), sedative medication (odds ratio, 2.6; 95% confidence interval, 1.2-5.4; P =.01), and comorbidity score (odds ratio, 1.2; 95% confidence interval, 1.0-1.4; P =.05). Mortality due to pneumonia was 23% at 14 days. Patients with pneumonia had a significantly higher mortality than did controls at 1 year (75% vs 40%; P<.001); survival curves converged at 2 years. In a Cox proportional hazards regression model, an episode of pneumonia was independently associated with mortality during follow-up (odds ratio, 2.6; 95% confidence interval, 1.7-3.9; P<.001).

Conclusions: Among long-term care patients closely matched for age, level of dependency, and duration of institutionalization, an episode of pneumonia is associated with significant excess mortality that persists for up to 2 years. Two identified risk factors, large-volume aspiration and receipt of sedating medication, are potentially amenable to intervention.