Identifying sepsis in the emergency room: the best clinical and laboratory variables

Background

Early diagnosis, antibiotics and supportive therapy are essential in sepsis. The diagnostic value of clinical and laboratory variables was evaluated in a prospective observational study.

Methods

A cohort of 404 adult patients admitted to the Department of Infectious Diseases from the emergency room for suspected severe infection was studied. A bacterial infection requiring antibiotic treatment was diagnosed in 306 patients (pneumonia 130 patients, urinary tract infection 80 patients, skin/soft tissue 43 patients, other bacterial infections 53 patients) and bacteriemia in 68 patients (most common isolates: pneumococci 19 patients, Escherichia coli 18 patients, Staphylococcus aureus eight patients, β-haemolytic streptococci seven patients). Nonbacterial infections or noninfectious conditions were diagnosed in 82 patients. The physiological variables recorded were: temperature, heart rate, blood pressure, respiratory rate (RR), oxygen saturation, urine output, and cerebral status. The laboratory variables were: C-reactive protein (CRP), lactate, bicarbonate, creatinine, urea, hemoglobin, white blood cells (WBC), neutrophils, platelets, International Normalized Ratio, D-dimer, albumin, bilirubin, procalcitonin (PCT), IL-6 and lipopolysaccharide binding protein (LBP).

Results

In a univariate analysis, PCT, IL-6, LBP, CRP, bilirubin and maximum RR during the first 4 hours (RR max 0 to 4 hours) were associated with bacteremia with P < 0.001 and CRP, PCT, IL-6, LBP, WBC, neutrophils, RR max 0 to 4 hours and hemoglobin were associated with a bacterial infection with P < 0.001. In a multivariate logistic regression, PCT, RR max 0 to 4 hours, bilirubin and CRP each contributed significantly to the accurate prediction of bacteremia. To predict a bacterial infection, CRP, WBC, hemoglobin and RR max 0 to 4 hours contributed significantly. The diagnostic accuracy of these variables was compared with the ability of the physicians caring for the patients to prescribe antibiotics appropriately. Of the 306 patients with bacterial infections requiring antibiotics, 76% had actually received antibiotics within 4 hours of arrival; and of the patients not requiring antibiotics, 54% were not on antibiotics after 4 hours. All variables tested had inferior diagnostic accuracy compared with the clinician.

Conclusion

We conclude that for the clinician, who evaluates patients with a suspected infection, special attention should be directed to the RR, CRP and WBC but the basic evaluation of the patient's medical history and a thorough clinical examination and assessment of the patient's general condition cannot be replaced by any laboratory parameter. Novel markers such as PCT, IL-6, and LBP seem not to give added value in the emergency room.