A new index to discriminate between iron deficiency anemia and thalassemia trait.

Background: The most common microcytic and hypochromic anemias are iron deficiencyanemia and thalassemia trait. Several indices to discriminate iron deficiency anemia fromthalassemia trait have been proposed as simple diagnostic tools. However, some of the bestdiscriminative indices use parameters in the formulas that are only measured in moderncounters and are not always available in small laboratories.The development of an index with good diagnostic accuracy based only on parametersderived from the blood cell count obtained using simple counters would be useful in theclinical routine. Thus, the aim of this study was to develop and validate a discriminativeindex to differentiate iron deficiency anemia from thalassemia trait. Methods: To develop and to validate the new formula, blood count data from 106 (thalassemiatrait: 23 and iron deficiency: 83) and 185 patients (thalassemia trait: 30 and iron deficiency:155) were used, respectively. Iron deficiency, _-thalassemia trait and _-thalassemia trait wereconfirmed by gold standard tests (low serum ferritin for iron deficiency anemia, HbA2> 3.5%for _-thalassemia trait and using molecular biology for the _-thalassemia trait).Results: The sensitivity, specificity, efficiency, Youden?s Index, area under receiver operatingcharacteristic curve and Kappa coefficient of the new formula, called the Matos & CarvalhoIndex were 99.3%, 76.7%, 95.7%, 76.0, 0.95 and 0.83, respectively. Conclusion: The performance of this index was excellent with the advantage of being solelydependent on the mean corpuscular hemoglobin concentration and red blood cell countobtained from simple automatic counters and thus may be of great value in underdevelopedand developing countries