Increased Long-Term Mortality in Patients Admitted to the Intensive Care Unit with Health-Care Associated Pneumonia

Abstract

BackgroundPneumonia is a leading cause of death in the United States. Guidelines for its diagnosis and management are periodically updated, but long-term mortality in critically ill patients has not been well studied.ObjectiveTo determine differences in one-year mortality between patients with community-acquired pneumonia (CAP) and healthcare-associated pneumonia or hospital-acquired pneumonia (HCAP/HAP).MethodsA retrospective multivariate analysis of a prospective cohort study that included all patients admitted to a single-center medical intensive care unit (ICU) from October 1, 2007, through September 30, 2008, with a diagnosis of pneumonia.ResultsThere were 181 patients admitted to the medical ICU with a diagnosis of pneumonia, 58.0% with HCAP/HAP and 42.0% with CAP. Those with HCAP/HAP had an older age distribution and higher proportions of cardiovascular (79.1% vs. 63.2%, P=0.02) and neurological (36.2% vs. 18.4%, P=0.01) comorbidities. The HCAP/HAP patients demonstrated an increased risk of death within one a year in the unadjusted analysis (HR 1.6, 95% CI 1.1-2.2, P=0.01) that did not remain significant in the multivariate analysis (HR 1.3, 95% CI 0.80-2.10. P=0.29) when adjusting for simplified acute physiology score (SAPS) II score, age category, source of admission and a history of diabetes mellitus, neurological disease or malignancy.ConclusionCompared to patients admitted to a medical ICU with CAP, those with HCAP/HAP had a higher one-year mortality that is accounted for by the increased co-morbidities associated with a HCAP/HAP diagnosis.Summary of Key PointsThe American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) developed and periodically update guidelines for the diagnosis and management of community-acquired and nosocomial pneumonia based on the patient-care setting in which pneumonia evolved. ATS/IDSA provides guidelines for empiric antibiotic choices based on the category of pneumonia that is diagnosed.Pneumonia is a significant cause of mortality in the United States and when combined with influenza ranks as the eighth leading cause of death nationwide yet little is known about the mortality of critically ill patients with pneumonia that require admission to a medical intensive care unit (ICU).Our findings suggest that older age, higher severity of illness at ICU admission, and chronic comorbid illnesses are the main contributors to long-term mortality from pneumonia requiring ICU admission.In this cohort, we found an independent association between increased mortality and admission from the general hospital ward rather than directly from the emergency department.Our study did not demonstrate that initial guideline-based antibiotic therapy was associated with a reduction in short-term mortality; however, it did demonstrate a high prevalence of resistant pathogens in HCAP/HAP patients, which reflects ATS/IDSA guideline expectations.