Etiology of community-acquired pneumonia in a population-based study: link between etiology and patients characteristics, process-of-care, clinical evolution and outcomes.

BACKGROUND: The etiologic profile of community-acquired pneumonia (CAP) for each age group could be similar among inpatients and outpatients. This fact brings up the link between etiology of CAP and its clinical evolution and outcome. Furthermore, the majority of pneumonia etiologic studies are based on hospitalized patients, whereas there have been no recent population-based studies encompassing both inpatients and outpatients. METHODS: To evaluate the etiology of CAP, and the relationship among the different pathogens of CAP to patients characteristics, process-of-care, clinical evolution and outcomes, a prospective population-based study was conducted in Spain from April 1, 2006, to June 30, 2007. Patients (age >18) with CAP were identified through the family physicians and the hospital area. RESULTS: A total of 700 patients with etiologic evaluation were included: 276 hospitalized and 424 ambulatory patients. We were able to define the aetiology of pneumonia in 55.7% (390/700). The most frequently isolated organism was S. pneumoniae (170/390, 43.6%), followed by C. burnetti (72/390, 18.5%), M. pneumoniae (62/390, 15.9%), virus as a group (56/390, 14.4%), Chlamydia species (39/390, 106%), and L. pneumophila (17/390, 4.4%). The atypical pathogens and the S. pneumoniae are present in pneumonias of a wide spectrum of severity and age. Patients infected by conventional bacteria were elderly, had a greater hospitalization rate, and higher mortality within 30 days. CONCLUSIONS: Our study provides information about the etiology of CAP in the general population. The microbiology of CAP remains stable: infections by conventional bacteria result in higher severity, and the S. pneumoniae remains the most important pathogen. However, atypical pathogens could also infect patients in a wide spectrum of severity and age.

Study of community-acquired pneumonia: incidence, patterns of care, and outcomes in primary and hospital care.

BACKGROUND: To asses the incidence, patterns of care, and outcomes of community-acquired pneumonia (CAP) in the population of a defined geographic area. METHODS: Prospective study conducted from April 1, 2006, to June 30, 2007. All adult patients (age ≥18) with CAP in the Comarca Interior region of northern Spain were identified through the region's 150 family physicians and the emergency department (ED) of the area's general teaching hospital. RESULTS: During a 15-month period, 960 patients with CAP were identified: 418 hospitalized and 542 ambulatory patients. The hospitalization rate was 43.5% and the global 30-day mortality was 4% (38 patients). Of the patients treated at home, most (90.4%) had mild pneumonia, only 3.1% (17 patients) were subsequently hospitalized, with a 30-day mortality rate of 0%. However, 48.9% were not treated according to antibiotic recommendations of the Spanish Society of Pneumology. Mean duration of return to daily activity was 18.8 days for the entire population. The incidence study was restricted to the first 12 months, during which 787 patients fulfilled the inclusion criteria. This represented an incidence of pneumonia of 3.1/1000 adults per year. Both the incidence of CAP and hospitalization for it rose with age. CONCLUSIONS: Our study offers information about CAP in the general population and provides feedback for the management of CAP. Although the selection of patients to be treated at home was appropriate, the choice of empiric antibiotic therapy for ambulatory CAP was problematic.