Diagnostic Usefulness of Basic Hematologic Tests for the Detection of Bacteremia in Febrile Patients with Neutrophilia

ABSTRACT

BACKGROUND: Alterations in blood cell count are well recognized features of bacteremia. The study objective was to determine the hematologic changes predictive of bacteremia. METHODS: We retrospectively studied febrile adult patients with neutrophilia and included patients were either bacteriologically proven cases or those who had clinically suspected bacterial infections. Hematologic findings derived from basic hematologic tests were compared between patients with and those without bacteremia. RESULTS: Of the 624 patients, 143 (22.9%) had significant bacteremia. The following items were significantly different between patients with and those without bacteremia by univariate analysis: absolute neutrophil count, neutrophil differential, absolute lymphocyte count, lymphocyte differential, platelet count and band-associated parameters such as absolute band neutrophil count (ABC). Multivariate analysis revealed platelet count, lymphocyte differential and ABC as independent predictors (P<0.0001, each). Platelet count, the most potent predictor of bacteremia, showed area under the curve (AUC) of 0.685. Analysis according to the primary diagnosis indicated that the most potent predictors of bacteremia in patients with respiratory tract, urinary tract and hepatobiliary system infections were platelet count (P=0.002, AUC=0.697), ABC (P=0.002, AUC=0.681) and neutrophil differential (P=0.0001, AUC=0.822), respectively. CONCLUSIONS: Simple variables obtained from basic hematologic tests were associated with bacteremia even in febrile patients with neutrophilia. In particular, very high neutrophil differential was highly predictive of bacteremia in patients with hepatobiliary system infections and its clinical usefulness needs to be elucidated in a prospective study.