New haematologic score to discriminate beta thalassemia trait from iron deficiency anaemia in a Spanish Mediterranean region.

Several studies have stablished discriminant formulas (DF) from red blood cell (RBC) data as simple, low time-consuming and inexpensive tools to differentiate β-thalassemia trait (β-TT) from iron deficiency anaemia (IDA). The aim of this work is to introduce new formulas and evaluate them in the differentiation of microcytic anaemia (MA) into either β-TT or IDA in the Mediterranean region of Tarragona. A total of 200 anonymized haematological determinations with MA were collected, 100 diagnosed of β-TT and 100 diagnosed of IDA. The cut-off values of new formulas were designed to differentiate β-TT from IDA groups and their diagnostic performance were compared with other published indices. Specifically, Martín-Sánchez index (MSI-I) = (%Micro-R/MCV) * MCHC * Hb and MSI-II = Hb * (MCHC + %Micro-R)/10. In addition, a new score: MSI-score = MCHC + MSI-I + MSI-II was proposed and evaluated in a transversal study with 200 patients. In our region, MSI-II index and MSI-score have demonstrated the best AUC and Youden's index (YI) (AUC = 0.956, YI = 81%; AUC = 0.971, YI = 87%, respectively) to discriminate β-TT from IDA groups. In summary, the new MSI-score with the highest AUC, the highest YI and the best percentage (93.5%) of correctly identified patients could be used as an efficient and robust tool in microcytic anaemia mass-screening programs in this region.