Etiology and outcome of community-acquired pneumonia in patients with diabetes mellitus.

STUDY OBJECTIVES: It has been suggested that diabetes mellitus is associated with an increased susceptibility to infection, the risk of using more aggressive therapeutic agents, and increased morbidity and mortality; however, current evidence supporting these events in the field of pneumonia is scarce. The aim of the present study was to provide information on clinical and microbiological characteristics and the outcome of community-acquired pneumonia in patients with diabetes mellitus.

DESIGN: Prospective study of cases.

SETTING: A university hospital in Lleida, Spain.

PATIENTS: During a 5-year period, we prospectively studied the clinical and radiologic characteristics, the spectrum of causative agents and other microbiological data, and the outcomes of 660 consecutive episodes of community-acquired pneumonia. Data derived from 106 patients with diabetes mellitus were analyzed and compared with data obtained from the remaining population.

MEASUREMENTS AND RESULTS: Patients with diabetes mellitus were significantly older (p = 0.001) and more frequently had other concomitant comorbid conditions (p = 0.018). Diabetes was also significantly associated with the development of pleural effusion (p = 0.015) and mortality (p = 0.002); for both events, diabetes remained as an independent predictive factor in multivariate analyses. By contrast, the incidence of the main etiologic agents, and the bacteremia or empyema rates did not show significant differences in relation to the remaining patients. In the subgroup of patients with diabetes, mortality was associated with the presence of multilobar infiltrates (p = 0.004), concomitant underlying diseases (p = 0.004), and some diabetes-related complications (nephropathy, p = 0.040; and vasculopathy, p = 0.002), although only multilobar infiltrates and comorbidities were selected as prognostic factors in the multivariate analysis.

CONCLUSIONS: In patients with community-acquired pneumonia, diabetes mellitus is associated with a poor prognosis, increasing the rate of pleural effusion and mortality. Our results suggest that this adverse outcome is more attributable to the underlying circumstances of patients than to uncommon microbiological findings.