Avaliação do desempenho de um novo índice na diferenciação entre anemia ferropriva e talassemias menores

Abstract

The most common microcytic and hypochromic anemias in our population are iron deficiency anemia, thalassemias and anemia of chronic disease. The differential diagnosis of these anemias is clinically important because they show different pathogenesis, treatment and prognosis. Currently, the diagnosis of these diseases is carried out through tests considered gold standard, often inaccessible to a less favored population. In contrast, several formulas described in the literature and obtained from the blood count parameters were developed in order to discriminate iron deficiency anemia from thalassemia minor. This study was designed to evaluate the performance of a New Index, besides nine other formulas in the differentiation between iron deficiency anemia and thalassemia minor, using conventional hematology and molecular methods as reference, as well as to diagnose, through these methods, the cases of -thalassemia in patients of the study. The sample consisted of two groups of patients treated at the both Hospital das Clinicas and Hospital Governador Israel Pinheiro in Belo Horizonte, Minas Gerais. Blood samples were collected in EDTA from 197 patients and obtained results for blood count and ferritin in the Hospital Governador Israel Pinheiro. For the 30 patients recruited at the Hospital das Clinicas blood samples were collected in EDTA and the data obtained through clinical and laboratory records. Blood samples were used to investigate the presence of seven deletional mutations and a non- deletional mutation causing -thalassemia trait. Laboratory data allowed the patients classification as having iron deficiency anemia and thalassemia minor. Using the parameters extracted from a simple blood count there were calculated values of nine indices. To verify the accuracy of these indices in differentiating iron deficiency anemia and thalassemia minor were determined sensitivity, specificity, efficiency, Youden index and area under ROC curve. To check the consistency of the results obtained through application of the indices with the results of gold standard tests, kappa coefficient was calculated. It was observed that among the nine tested formulas, Green and King Index, the New Index and RDW Index showed excellent performance in discriminating between iron deficiency anemia and thalassemia minor and could be used as a tool for screening of these microcytic anemias. A study on the frequency of -thalassemia in our population it was observed that 20,3% of the 227 patients enrolled in the present study were carried of the deletion 3.7 Kb. So, the investigation in blood samples from patients with microcytic and hypochromic anemia, by molecular methods, revealed a high frequency of the -thalassemia in groups of patients from two public hospitals of Minas Gerais state, indicating the necessity of introducing such methods to correctly diagnose specific cases.