Community-acquired pneumonia (CAP) is a frequent infectious respiratory disease which remains a major cause of morbidity and mortality in developed countries. Its incidence varies and is higher at the extremes of age, both in very young children and in elderly adults. Pneumonia is more common in males than females and this difference increases with age. This is probably an effect of smoking and associated pulmonary co-morbidities. Since pneumonia is an infectious disease that does not require notification (except Legionella spp.) it is difficult to determine its incidence. Population-based studies are the best epidemiological investigations to determine the incidence of CAP. For example, Almirall and colleagues performed one such study in a region close to Barcelona, Spain.1 The incidence rate in that study was 1.62 cases per 1000 inhabitants. In another more recent study from the same group, the incidence was 1.54 cases per 1000 habitants aged >14 years.2 In a study from Finland the incidence was higher, with 9 cases per 1000 inhabitants aged >14 years3. The incidence of CAP varies between studies and that might reflect different populations included in the studies and different investigational methodologies used. In general we can say that the overall incidence of CAP ranges between 1.5 and 3 cases per 1000 inhabitants.

The percentage of patients with CAP requiring hospitalisation is not well known and probably varies from country to country, reflecting different criteria for hospitalisation and different resources available. In the population-based study by Almirall et al,1 the rate of admission was 61%, a figure that in our opinion is very high and probably reflects practice before the widespread use of prognostic scales such as the PSI (Pneumonia Severity Index) or CURB65. There is not …