title: A new index to discriminate between iron deficiency anemia and thalassemia trait.
abstract: BACKGROUND
  The most common microcytic and hypochromic anemias are iron deficiency anemia and thalassemia trait. Several indices to discriminate iron deficiency anemia from thalassemia trait have been proposed as simple diagnostic tools. However, some of the best discriminative indices use parameters in the formulas that are only measured in modern counters and are not always available in small laboratories. The development of an index with good diagnostic accuracy based only on parameters derived from the blood cell count obtained using simple counters would be useful in the clinical routine. Thus, the aim of this study was to develop and validate a discriminative index to differentiate iron deficiency anemia from thalassemia trait.
  
  
  METHODS
  To develop and to validate the new formula, blood count data from 106 (thalassemia trait: 23 and iron deficiency: 83) and 185 patients (thalassemia trait: 30 and iron deficiency: 155) were used, respectively. Iron deficiency, β-thalassemia trait and α-thalassemia trait were confirmed by gold standard tests (low serum ferritin for iron deficiency anemia, HbA2>3.5% for β-thalassemia trait and using molecular biology for the α-thalassemia trait).
  
  
  RESULTS
  The sensitivity, specificity, efficiency, Youden's Index, area under receiver operating characteristic curve and Kappa coefficient of the new formula, called the Matos & Carvalho Index were 99.3%, 76.7%, 95.7%, 76.0, 0.95 and 0.83, respectively.
  
  
  CONCLUSIONS
  The performance of this index was excellent with the advantage of being solely dependent on the mean corpuscular hemoglobin concentration and red blood cell count obtained from simple automatic counters and thus may be of great value in underdeveloped and developing countries.
authors: Instituto Federal de Minas Gerais (IFMG), Ouro Preto, MG, Brazil; Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. Electronic address: januaria.matos@ifmg.edu.br.
authors: Januária F
authors: JF
authors: Matos
authors: Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
authors: Luci M S
authors: LM
authors: Dusse
authors: Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
authors: Karina B G
authors: KB
authors: Borges
authors: Hospital Odilon Behrens, Belo Horizonte, MG, Brazil.
authors: Ricardo L V
authors: RL
authors: de Castro
authors: Universidade Federal de Ouro Preto (UFOP), Ouro Preto, MG, Brazil.
authors: Wendel
authors: W
authors: Coura-Vital
authors: Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
authors: Maria das G
authors: Md
authors: Carvalho
keywords: Iron deficiency anemia; New index; Thalassemia trait