Epidemiology of community-acquired pneumonia in adults: a population-basedstudy

In this prospective study, the authors assessed the incidence, aetiology, a nd outcome of patients with community-acquired pneumonia in the general pop ulation, From December 1993 to November 1995, a study was performed in a mixed resid ential-industrial urban population of the "Maresme" region in Barcelona, Sp ain. All subjects greater than or equal to 14 yrs of age (annual average po pulation size 74,368 inhabitants) with clinically suspected community-acqui red pneumonia were registered. All cases were re-evaluated by chest radiogr aphs on the 5th day of illness and at monthly intervals until complete reco very. Urine and blood samples were obtained for culture and antigen detecti on. When lower respiratory tract secretions were obtained, these were also cultured. There were 241 patients with community-acquired pneumonia, with an annual i ncidence rate of 1.62 cases (95% confidence interval, 1.42-1.82) per 1,000 inhabitants. incidence rates increased by age groups and were higher in mal es than in females. Of 232 patients with aetiological data, 104 had an iden tifiable aetiology, A total of 114 pathogens were found (single pathogen 94 , two pathogens Ill), There were 81 episodes of bacterial infection and 33 of viral infection. The most common pathogens were Streptococcus pneumoniae , Chlamydia pneumoniae, and influenza A and B viruses, No Ease of Hantaviru s infection was found, The rate of hospital admission was 61.4% with a mean +/-SD, length of 11.7+/-10.1 days, a mean period of 23.0+/-14.3 days inacti vity, and an overall mortality rate of 5%. The high rate of hospital admission, prolonged stay in hospital, and long p eriod of inactivity all continue to constitute a social and health care bur den of community-acquired pneumonia.