[Epidemiology of community-acquired pneumonia in adults]

Respiratory diseases represent the third cause of death in Chilean population, after cardiovascular diseases and malignancy. Fifty percent of deaths caused by respiratory diseases in adults are attributable to pneumonia. In Chile, they represent the main cause of death due to infectious diseases and the first specific one in senescent adults over 80 years old. The incidence and mortality of community acquired pneumonia (CAP) increase in both extreme ages of life (less than one year old and over 65 years old). In the population over 65 years old, mortality is extremely increased, rising to rates of 6.6 deaths per 1.000 inhabitants. High variability in pneumonia hospitalization rate has been observed in different geographic areas, probably due to different medical criteria used to evaluate the severity of illness, access to healthcare systems and characteristics of the evaluated population. About 20% of patients affected with CAP require hospitalization due to the severity of pulmonary infection and to the risk of complications or death, and the necessity of healthcare resources are focused in these patients. Several clinical-epidemiological parameters able to modify clinical presentation and severity of pneumonia have been identified, such as advanced age, presence of co-morbidities, host immune competence, tobacco and alcohol consumption, place of acquiring the infection, etiology and environmental pollution.