Eosinopenia is a reliable marker of sepsis on admission to medical intensive care units

Abstract

Introduction: Eosinopenia is a cheap and forgotten marker of acute infection that has not been evaluated previously in intensive care units (ICUs). The aim of the present study was to test the value of eosinopenia in the diagnosis of sepsis in patients admitted to ICUs.

Methods: A prospective study of consecutive adult patients admitted to a 12-bed medical ICU was performed. Eosinophils were measured at ICU admission. Two intensivists blinded to the eosinophils classified patients as negative or with systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, or septic shock.

Results: A total of 177 patients were enrolled. In discriminating noninfected (negative + SIRS) and infected (sepsis + severe sepsis + septic shock) groups, the area under the receiver operating characteristic curve was 0.89 (95% confidence interval (CI), 0.83 to 0.94). Eosinophils at <50 cells/mm3 yielded a sensitivity of 80% (95% CI, 71% to 86%), a specificity of 91% (95% CI, 79% to 96%), a positive likelihood ratio of 9.12 (95% CI, 3.9 to 21), and a negative likelihood ratio of 0.21(95% CI, 0.15 to 0.31). In discriminating SIRS and infected groups, the area under the receiver operating characteristic curve was 0.84 (95% CI, 0.74 to 0.94). Eosinophils at <40 cells/mm3 yielded a sensitivity of 80% (95% CI, 71% to 86%), a specificity of 80% (95% CI, 55% to 93%), a positive likelihood ratio of 4 (95% CI, 1.65 to 9.65), and a negative likelihood ratio of 0.25 (95% CI, 0.17 to 0.36).

Conclusion: Eosinopenia is a good diagnostic marker in distinguishing between noninfection and infection, but is a moderate marker in discriminating between SIRS and infection in newly admitted critically ill patients. Eosinopenia may become a helpful clinical tool in ICU practices.

Figure 1

Patients included and excluded from the study. ICU, intensive care unit; SIRS, systemic inflammatory response syndrome.

Figure 2

Eosinophil cell count and C-reactive protein level in the different diagnostic groups. Box plot of eosinophil cell count and C-reactive protein (CRP) level in the different diagnostic groups. SIRS, systemic inflammatory response syndrome. Central line, median; boxes, 25th to 75th percentiles; whiskers, 95% confidence intervals.

Figure 3

Eosinophil cell count and C-reactive protein level for discrimination of noninfection and infection. Receiver operating characteristic (ROC) curve of eosinophil cell count and C-reactive protein (CRP) level for the discrimination of noninfected patients (negative + systemic inflammatory response syndrome) and infected patients (sepsis + severe sepsis + septic shock). Areas under the ROC curves were 0.89 (95% confidence interval, 0.83 to 0.94) for eosinophils and 0.77 (95% confidence interval, 0.70 to 0.84) for CRP. Comparison of the areas under ROC curves between eosinophils and CRP, P = 0.010.

Figure 4

Eosinophil cell count and C-reactive protein level for comparison of systemic inflammatory response syndrome and infection (P < 0.001). Box plot of eosinophil count and C-reactive protein (CRP) level for comparisons between the systemic inflammatory response syndrome (SIRS) group and the infected group (sepsis + severe sepsis + septic shock). Central line, median; boxes, 25th to 75th percentiles; whiskers, 95% confidence intervals.P < 0.001 between eosinophils and CRP groups.

Figure 5

Eosinophil cell count and C-reactive protein level for discrimination of systemic inflammatory response syndrome and infection. Receiver operating characteristic (ROC) curve of eosinophil cell count and C-reactive protein (CRP) level for the discrimination of systemic inflammatory response syndrome patients and infected patients (sepsis + severe sepsis + septic shock). Areas under the ROC curves were 0.84 (95% confidence interval, 0.74 to 0.94) for eosinophils and 0.77 (95% confidence interval, 0.67 to 0.87) for CRP. Comparison of the areas under ROC curves between eosinophils and CRP, P = 0.175.