Red cell indices: differentiation between β-thalassemia trait and iron deficiency anemia and application to sickle-cell disease and sickle-cell thalassemia

In Tunisia, thalassemia and sickle cell disease represent the most prevalent monogenic hemoglobin disorders with 2.21% and 1.89% of carriers, respectively. This study aims to evaluate the diagnosis reliability of a series of red blood cell indices and parameters in differentiation of beta-thalassemia trait (β-TT) from iron deficiency anemia (IDA) and between homozygous sickle cell disease (SS) and sickle cell-thalassemia (ST). The study covered 384 patients divided into three groups. The first one is composed of 145 control group, the second consists of 57 β-TT and 52 IDA subjects and the last one with 88 SS and 42 ST patients. We calculated sensitivity, specificity, positive-predictive values, negative-predictive values, percentage of correctly identified patients and Youden’s index for each indice. We also established new cut-off values by receiver operating characteristic curves for each indice. An evaluation study was performed on another population composed of 106 β-TT, 125 IDA, 31 SS and 17 ST patients. Srivastava Index, mean corpuscular hemoglobin, red blood cell, Mentzer Index (MI) and mean corpuscular hemoglobin concentration show the highest reliability in discriminating β-TT from IDA with new cut-offs slightly different from those described in literature. Ehsani Index, mean corpuscular volume, MI, Shine and Lal Index and Sirdah Index are the most powerful in the differentiation between SS and ST. The effectiveness and the simplicity of calculation of these indices make them acceptable and easy to use for differential diagnosis.