Agreement assessment between hemoglobin and hematocrit to detect anemia prevalence in children less than 5 years old

1Departamento de Saúde Coletiva, Universidade Federal de Mato Grosso (UFMT) Cuiabá (MT), Brazil. 2Centro de Pesquisas Epidemiológicas, Universidade Federal de Pelotas (UFPEL) Pelotas (RS), Brazil. 3MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke’s Hospital Cambridge, UK. 4Instituto de Estudos em Saúde Coletiva, Universidade Federal do Rio de Janeiro (UFRJ) Rio de Janeiro (RJ), Brazil. 5Faculdade de Saúde Pública, Universidade de São Paulo (USP) São Paulo (SP), Brazil. Study carried out at Federal University of Mato Grosso (UFMT) – Cuiabá (MT), Brazil. Correspondence: Gisela Soares Brunken – Rua Buenos Aires, 726, apto 102, CEP: 78060-634 – Cuiabá (MT), Brazil – Email: [email protected] Financial support: none. Conflict of interests: nothing to declare. Abstract This study aimed to assess the extent of agreement between hemoglobin (Hb) and hematocrit (Ht), while also verifying whether anemia prevalence can be determined by hematocrit cut-off points. A hundred pairs of capillary Hb and Ht of children less than 5 years old were analyzed. The Hb and Ht concentrations were measured using HemoCue and microhematocrit centrifuge, respectively. The Bland and Altman’s method was used to assess the agreement between ‘observed Hb’ and ‘Hb estimated through Ht’ (Hb = Ht/3). The ROC curve was constructed based on the reference to anemia classification according to Hb. The subjects were classified according to the status of anemia obtained through the Ht, also evaluating the agreement regarding Hb. The area under the ROC curve identified that Ht <35% correctly classified 85% of subjects with Hb <11.0 g/dL. However, the cut-off point of <33% showed higher kappa (k = 0.49 against 0.41) and higher relative agreement (82% vs. 74%) compared to Ht <35%. Our findings indicate that capillary Hb and Ht could be used either together or separately to assess the prevalence of anemia. Considering the need to identify iron deficiency anemia with a single indicator in population studies, the use of Ht would be simpler and cost-saving.