Severe sepsis and septic shock remain major public health threats worldwide. Broad global variations in mortality have been reported, ranging from 22% to more than 75%. In the December issue of Lancet Infectious Diseases, Society of Critical Care Medicine past-president Mitchell M. Levy and investigators from the Surviving Sepsis Campaign compared models of care and outcomes of compliance, mortality and length of stay for patients with severe sepsis and septic shock in the United States and Europe.

Prospectively collected data from January 2005 to January 2010 were examined. The primary outcome of interest was change in compliance with sepsis bundle targets over time. Secondary outcomes included hospital mortality, hospital length of stay and intensive care unit (ICU) length of stay. A random effects logistic regression model was used to estimate hospital mortality and a random-effects linear regression model was used to find the relationship between lengths of stay and geographic region.

In the study, 18,766 patients from the United States and 6,609 patients from Europe met the inclusion criteria for analysis. Compliance with all bundle elements was higher in the United States (21.6% vs. 18.4%, P<0.0001), although compliance for four of six individual bundle elements was statistically significantly higher in Europe. Patients in Europe had a higher incidence of multiple organ dysfunction and nosocomial infections, and a higher unadjusted mortality rate compared to the United States. Unadjusted ICU mortality in Europe was higher (odds ratio [OR] 1.61; 95% confidence interval [CI], 1.32 to 1.96; P<0.0001); however, after adjustment for multiple variables associated with patient illness severity — such as type of organ failure, resuscitation performance and other patient-related variables — the mortality rate difference between the two regions disappeared (OR 1.19; 95% CI, 0.96 to 1.47; P=0.11). Adjusted ICU length of stay was longer in Europe than in the United States (P<0.0001). Further, a sensitivity analysis using propensity score matching confirmed the results from the logistic regression analysis.

The Surviving Sepsis Campaign database has several limitations. Patients are self-selected, and it is possible that the results from this study may not be generalizable for other regions of the world. The true mortality rate is unknown since some patients with severe sepsis might have been admitted to a general ward and discharged without an ICU admission. No other studies have directly compared sepsis outcomes in Europe and the United States. The results of this study raise important questions about different models of care, outcomes and compliance with accepted management bundles for severe sepsis and septic shock.

Concise Critical Appraisal is a regular feature authored by SCCM member Samuel M. Galvagno Jr., DO, PhD. Each installment highlights journal articles most relevant to the critical care practitioner.