Procalcitonin as a marker of bacteremia in patients with fever and acute lymphoblastic leukemia

Background: Children undergoing treatment for acute lymphoblastic leukemia (ALL) often present to the emergency department (ED) with a fever. They are at high risk of bacteremia secondary to being immunocompromised. Recent reports indicate that procalcitonin (PCT) is a useful marker of bacteremia in children. Objective: Our objective was to evaluate the clinical utility of PCT as a rapid marker of bacteremia in children with ALL presenting to the ED with a fever. In addition, we compared the results of PCTwith white blood cell (WBC) count, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Methods: Retrospective chart reviews were conducted of 492 patients with a total of 735 visits presenting to the ED from January 2009 to June 2012 with fever and a history of ALL where a PCT and a blood culture (BC) were obtained,. Positive BCs determined to be contaminants were excluded. The predictive powers of PCT,WBC, ESR, and CRP for bacteremiawere evaluated using the area under the receiver operating characteristic curve with 95%confidence intervals (CI). In addition, each of the 4 markerswere also examined in a logistic regressionmodel as a potential predictor of the BC result. Results: A total of 735 PCT values were correlated with BC results. There were 76 (10.3%) true-positive BCs. The area under the receiver operating characteristic curve was 0.729 (95% CI, 0.661-0.792) for PCT, 0.685 (95% CI, 0.531-0.823) for ESR, 0.622 (95% CI, 0.460-0.796) for CRP, and 0.567 (95% CI, 0.483-0.649) for WBC. When logistic regression was used, the transformation log PCT was significantly associated with BC result whereas each of the other 3 markers, after appropriate transformation to remove heavy skewness, was not significant (all P > 0.1). A doubling of PCT was associated with an odds ratio of 1.32 for positive BCs (95% CI, 1.15-1.53). Conclusions: Procalcitonin value was significantly associated with positive BC (P < 0.0001). The diagnostic performance of PCTwas better than the other markers of inflammation. Its use in the ED in a select population of patients may be of significant value in identifying bacteremia. This has the potential to lead to a decrease in unwarranted use of antibiotics, hospital length of stay, and health care expenditures.