Purpose of review: Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are diseases with a significant influence in the public health. A better knowledge of their epidemiology could help to improve the outcome of these diseases.
Recent findings: Although the clinical criteria of the American-European Consensus Conference definitions for ALI and ARDS are simple, there is a risk of misclassification due to a poor reliability. Except for new emerging infectious diseases, such as severe acute respiratory syndrome, the etiology of ALI/ARDS has remained the same for several years. The only recent innovation is the hypothesis that pulmonary ARDS and extrapulmonary ARDS could be different clinical entities. In recent years, there has been a special interest in the study of genetic predisposition to development ALI/ARDS. Recent studies have estimated the incidence of these diseases to be between 15 and 34 cases per 100,000 inhabitants per year. This wide range could stem from differences in the methodology used to calculate the incidence or could be a true variation due to regional differences. Mortality rate of ALI/ARDS have remained steady for several years. Respiratory failure is the cause of the death in less than 20% of the patients.
Summary: The epidemiology of ALI and ARDS has some issues to improve, such as the accuracy of the clinical criteria of ALI/ARDS. Future research must to include study of genetic polymorphisms of the mediators involve in the development of ALI/ARDS. Studies to define better the population at risk are necessary to estimate better their true incidence.