Prognostic significance of the neutrophil count in immunocompetent patients with bacteraemia

Abstract

To examine the prevalence of neutropaenia in immunocompetent, bacteraemic patients, and whether it carries an independent risk for mortality, we surveyed 2096 bacteraemic patients without malignant diseases, and who were not receiving cytotoxic drugs. The granulocyte count on the day of the first positive blood culture was < 1 x 10(9) cells/l in 33 patients (1.7%, group 1); 1.0-4.0 x 10(9) cells/l in 154 patients (7.9%, group 2); 4.0-8.0 x 10(9) cells/l in 564 patients (29%, group 3); 8.0-20.0 x 10(9) cells/l in 1034 patients (53%, group 4); and > 20.0 x 10(9) cells/l in 163 patients (8.4%, group 5). The mortality rates in the five groups were 39.4%, 18.8%, 18.1%, 25.7% and 25.8%, respectively (p = 0.0001). The main pathogens in group 1 were Staphylococcus aureus in 25% of patients and Pseudomonas sp. in 23%. Mortality in group 1 patients was higher than in the other patients (odds ratio 1.4, 95% CI 1.1-1.9]. Mortality was also significantly higher in group 2 patients with high blood urea nitrogen. The percentage of neutropaenia, septic patients without known risk factors for neutropaenia is small, but their mortality is high. Overall mortality in patients with relative neutropaenia (1.0-4.0 x 10(9) cells/l) is low, but a subgroup of patients with high blood urea nitrogen is at considerable risk for a fatal outcome. High leucocyte counts are also a marker of increased risk for mortality, but this association is not an independent prognostic factor.