Epidemiologic trends of sepsis in western countries.

Since the American College of Chest Physicians (ACCP) and the Society of Critical care Medicine (SCCM) published the first consensus definition of syndromes related to sepsis in 1992, the knowledge of epidemiology of sepsis has clearly improved, although no prospective studies have been performed to analyse the incidence of sepsis in general population. There are differences in epidemiologic trends in sepsis between western countries and low-income and middle-income countries. In the United States (US), most of epidemiologic studies have been based on large, administrative databases, reporting an increase in the incidence of severe sepsis over years. In general, studies describing epidemiology of sepsis outside the US use clinical definitions and intensive care unit (ICU) observational cohort designs instead of administrative databases and definitions. Incidence of sepsis has increased over years, probably due to progressive aging of population, the existence of more comorbidities and maybe the liberal use of sepsis codification, by including patients with less severity. Notwithstanding, mortality due to sepsis is clearly decreasing over years, probably to improvement in ICU care, although absolute mortality is growing on account of the raise in incidence. Risk factors for sepsis are the two ends of life, male sex, US black race, presence of comorbidities and certain genetic variants. Respiratory tract infections are the most common source of sepsis, and, nowadays, Gram-positive infections are more frequent that Gram-negative sepsis in most prospective studies.