title: Discrimination indices as screening tests for beta-thalassemic trait.
abstract: The two most frequent microcytic anemias are beta-thalassemic trait (beta-TT) and iron deficiency anemia (IDA). Several discrimination indices have been proposed to distinguish between these two conditions. These indices are derived from several simple red blood cell indices, like red blood cell (RBC) count, mean cell volume, and RBC distribution width (RDW), as these are provided by electronic cell counters. The purpose of the study is to examine the diagnostic accuracy of six discrimination indices in the differentiation between IDA and beta-TT. The six discrimination indices that were examined were as follows: Mentzer Index (MI), Green & King Index (G&K), RDW Index (RDWI), England & Fraser Index (E&F), RDW, and RBC count. We calculated these indices on 373 patients (205 men, 168 women) with beta-TT and 120 patients (50 men, 70 women) with IDA, as well as their sensitivity, specificity, positive and negative prognostic value, efficiency, and Youden's index (YI). G&K shows the highest reliability, followed by E&F, RBC count, MI, and RDWI. On the contrary, RDW completely failed to differentiate between IDA and beta-TT. G&K proved to be the most reliable index as it had the highest sensitivity (75.06%), efficiency (80.12%), and YI (70.86%) for the detection of beta-TT. These six discrimination indices cannot be relied on for a safe differential diagnosis between beta-TT and IDA. They do have high specificity, but their sensitivity for the detection of beta-TT is not satisfactory. Consequently, they cannot be used neither as a screening tool for beta-TT because they could result in a significant number of false negative results.
authors.affiliation: First Propedeutic Department of Internal Medicine, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece. ntaiosgeorge@yahoo.gr
authors.forename: George
authors.initials: G
authors.lastname: Ntaios
authors.forename: Anastasia
authors.initials: A
authors.lastname: Chatzinikolaou
authors.forename: Zoi
authors.initials: Z
authors.lastname: Saouli
authors.forename: Fotios
authors.initials: F
authors.lastname: Girtovitis
authors.forename: Maria
authors.initials: M
authors.lastname: Tsapanidou
authors.forename: Georgia
authors.initials: G
authors.lastname: Kaiafa
authors.forename: Zisis
authors.initials: Z
authors.lastname: Kontoninas
authors.forename: Androula
authors.initials: A
authors.lastname: Nikolaidou
authors.forename: Christos
authors.initials: C
authors.lastname: Savopoulos
authors.forename: Ifigenia
authors.initials: I
authors.lastname: Pidonia
authors.forename: Stiliani
authors.initials: S
authors.lastname: Alexiou-Daniel
mesh_terms: D018798:Anemia, Iron-Deficiency / Q000175:diagnosis*; D003937:Diagnosis, Differential; D004909:Erythrocyte Indices; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D017086:beta-Thalassemia / Q000175:diagnosis*