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

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/mm(3) 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/mm(3) 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.