Expressão do CD64 como preditor de cultural positivo em crianças com neutropenia febril

Introduction : One in every 25 children with cancer will die from therapy complications: it means one in six deaths. Between these patients, a major cause of death remains infection. This condition often presents as fever with neutropenia, better known as “febrileneutropenia. " Early recognition of infectious processes in neutropenic patients is hampered by the fact that these may have dissimilar and non-specific clinical presentations, pending the onset of fever to start treatment with antibiotics. The CD64 is a neutrophil surface marker, detectable by flow cytometry tests, and are not expressed in non-sensitized neutrophils. When the neutrophil is exposed to TNF-alpha and other inflammatory mediators, it is activated and is measured via the CD64 index. Rationale:The early diagnosis of sepsis with positive blood culture in febrile neutropenic children is of utmost importance. Laboratory tests available help us little in the moment this patient arrives at the hospital. The early diagnosis of a bacterial infection in these patients allows a better management of antibiotic therapy and, consequently, an improvement in survival. Objectives: The main objective of this paper is to evaluate the existence of a relationship between the index value of CD64 on the first day of febrile neutropenia with positive blood culture. The correlation with other parameters such as leukocyte count, CRP and ESR was also evaluated. Methodology: This is a cases-control, prospective, diagnosis studythat included 64 episodes of neutropenia. The casesgroup(n=14) was defined by those with positive blood cultures and the control(n=50) one with negative blood cultures. Because it is a non parametric variable, we used the Mann-Whitneycorrelation test to relate the index of CD64 with the result of blood culture in each group and with the other variables. A ROC (Receiver Operating Characteristic) curve was used to assess the competence of the CD64 index to predict the outcome of blood culture.The median rate of CD64 in the case group was 2,1 (±3,9) and controls for the group was 1,76(±5,02). The Mann-Whitney tests were not able to show the relationship between the value of CD64 indexand the results of blood cultures. The CD64 index was also not correlated with the positivity of CRP. The ROC curve did not show that the CD64 index was able to predict the positivity of blood culture.Regarding efficacy measurmements, sensibility was 64,3%, specificity 42%, positive predictive value 23,7% and negative predictive value 80%. The linear value of CRPshowedno statisticallysignificant differencebetween the groupsof blood cultures. For CRP, the efficacy measurements were sensibility 71,4%, specificity 32%, positive predictive value 22,7% and negative predictive value 80%. Conclusion:CD64 index was not suitable to predict the positivity of blood cultures in this specific population of patients with febrile neutropenia.Also thelinearvalues of CRP showed no statistically significant difference between the blood culture groups.Therefore, both exams should not be used in order to predict positivity of cultural in neutropenic febrile childen.