Community-acquired legionella pneumonia in elderly patients: characteristics and outcome

To compare the risk factors, clinical and laboratory features, and outcome of community-acquired pneumonia (CAP) caused by Legionella pneumophila in elderly (aged > or =65) and younger patients.

Prospective enrollment of subjects with retrospective data analysis.

A 630-bed tertiary center in Badalona (Barcelona), Spain.

A total of 158 patients diagnosed with CAP caused by L. pneumophila from 1994 to 2004: 104 younger than 65 and 54 aged 65 and older.

Epidemiological, clinical, laboratory, and radiological data and the outcome of the two groups were compared using univariate and multivariate analysis.

Underlying diseases, such as chronic pulmonary diseases, diabetes mellitus, neuromuscular diseases, and heart failure; risk of aspiration; and therapy with corticosteroids were significantly more frequent in patients aged 65 and older. Patients younger than 65 were more likely to be male and have toxic habits (cigarette smoking, alcoholism) and human immunodeficiency virus infection than older patients. Fever, nonrespiratory symptoms (diarrhea and headache), and some laboratory abnormalities (hyponatremia (serum sodium concentration <130 mmol/L) and high aspartate aminotransferase and creatinine kinase levels) were significantly less frequent in patients aged 65 and older than in younger patients. No significant differences were observed between the two groups in the frequency of higher-severity risk classes and intensive care unit admission or in outcome (complications and mortality).

Elderly patients with CAP caused by L. pneumophila had a higher frequency of underlying comorbidities and presented less frequently with fever and classical nonrespiratory symptoms and laboratory abnormalities of Legionnaires' disease than younger patients, although greater severity of illness at onset and higher mortality were not significantly different between the two age groups.