Severe sepsis epidemiology: sampling, selection, and society.

Three new articles in Critical Care add to an expanding body of information on the epidemiology of severe sepsis. Although there have been a range of approaches to estimate the incidence of severe sepsis, most studies report severe sepsis in about 10 +/- 4% of ICU patients with a population incidence of 1 +/- 0.5 cases per 1000. Importantly, the availability of ICU services may well determine the number of treated cases of severe sepsis, and it seems clear that these studies are reporting the treated incidence, not the incidence, of severe sepsis. In the future, we must focus on whether all severe sepsis should be treated, and, consequently, what level of ICU services is optimal.