Bloodstream Infection-Associated Sepsis and Septic Shock in Critically III Adults: A Population-Based Study

Background: Few studies have investigated the epidemiology of sepsis and septic shock in a large population and none have been from Canada. The objective of this study was to define the epidemiology of bloodstream infection (BSI)-associated sepsis and septic shock among all critically ill patients in a large, fully integrated health region in Canada. Patients and Methods: All critically ill adults admitted to multidisciplinary intensive care units (ICU) in the Calgary Health Region during May 1, 1999 to April 30, 2000 were included. Clinical, microbiologic and outcome information was obtained from regional databases. Results: We surveyed 1,981 patients having at least one ICU admission. Systemic inflammatory response syndrome (SIRS) was diagnosed in 92%, BSI-associated sepsis (BSI with SIRS) in 6% and BSI-associated septic shock (BSI with SIRS and hypotension) in 3%; respective hospital mortality rates were 36%, 40% and 49%. The most common BSI etiologies were Staphylococcus aureus, Escherichia coli and Streptococcus species; only one isolate (1%) was highly antibiotic resistant. Independent risk factors for death among patients with SIRS included age ( greater than or equal to 65), hypothermia (< 35 degree C), and higher APACHE II and TISS scores. A surgical diagnosis was associated with decreased mortality risk. Neither a positive blood culture nor hypotension at presentation independently predicted death. Conclusion: Knowledge of the epidemiology of these syndromes is important for assessing the burden of disease and providing background information for investigating new therapies.