Septic shock definitions and associated outcomes in blood culture positive critically ill patients

The proposed definition of septic shock in the Sepsis-3 consensus statement has been previously validated in critically ill patients. However, the subset of critically ill patients with sepsis and positive blood cultures needs further evaluation. To compare the combined (old and new septic shock) versus old definition of septic shock in sepsis patients that have positive blood cultures and are critically ill.

A retrospective cohort study of adult patients (age ≥18 years), who had evidence of positive blood cultures, requiring intensive care unit (ICU) admission at a large tertiary care academic center from January 2009 through October 2015. Eligible subjects who opted out of research participation, those requiring intensive care admission after elective surgery, and those who were deemed to have a low probability of infection were excluded. Basic demographics data, clinical and laboratory parameters, and outcomes of interest were pulled from the validated institutional database/repository and contrasted between the patients who qualified the new and old definitions criteria (combined) of septic shock versus the group meeting the old septic shock criteria only.

We included a total of 477 patients in the final analysis who qualified for old and new septic shock definitions. For the entire cohort, median age was 65.6 (IQR, 55-75) years, with male predominance (N=258, 54%). When compared to patients in the group who only met the old definition (N=206), the patients who met the combined (new or both new and old, N=271) definition had a higher APACHE III scores, 92 (IQR, 76-112) vs. 76 (IQR, 61-95), P<0.001; a higher SOFA day-1 score of 10 (IQR, 8-13) vs. 7 (IQR, 4-10), P<0.001, but did not differ significantly in age 65.5 years (IQR, 55-74) vs. 66 years (IQR, 55-76) years, P=0.47. The patients who met the combined (new or both new and old) definition had higher chances of having conservative resuscitation preferences (DNI/DNR); 77 (28.4) vs. 22 (10.7), P<0.001. The same group also had worse outcomes in terms of hospital mortality (34.3% vs. 18%, P<0.001) and standardized mortality ratio (0.76 vs. 0.52, P<0.04).

In patients with sepsis with positive blood cultures, the group of patients meeting the combined definition (new or both new and old) have higher severity of illness, higher mortality, and a worse standardized mortality ratio as compared to patients meeting the old definition of septic shock.