Discrimination indices as screening tests for β-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.

Physiological and pathological population dynamics of circulating human red blood cells

“…All 22 IDA cases were correctly classified, and 27/28 TT cases were correctly classified for an overall diagnostic accuracy of 98%. We find this accuracy to be superior to that of four commonly cited discriminant functions (20): The Green and King formula yielded an accuracy of 92%; Micro/Hypo, 84%; Mentzer, 68%; and England and Fraser, 57%. See ref.…”

“…Fig. 4 shows that this D h threshold had a diagnostic accuracy of 98%, correctly identifying 22/22 cases of IDA and 27/28 cases of TT and outperforming other published approaches by between 6% and 41% (20). See Diagnosis of Microcytic Anemia in Materials and Methods for details.…”

“…2 shows that D h differentiates IDA and TT, the two most common causes of microcytic anemia. TT is one of the most commonly screened conditions in the world, but existing diagnostic methods either are too expensive or have unacceptably low diagnostic accuracy, with false positive rates of up to 30% (19,20). Our model provides a possibly more accurate way to distinguish these conditions.…”

Prognostic value of red blood cell distribution width in patients with left ventricular systolic dysfunction: Insights from the COMMIT-HF registry

“…Red blood cell distribution width (RDW) reflects variability in the size of circulating erythrocytes and is a marker of anisocytosis [1]. In recent years, anisocytosis has emerged as a prognostic biomarker in cardiovascular disease.…”

Salivary ferritin and iron as a marker and new discriminating indices between iron deficiency anemia and thalassemia: a meta-analysis

“…Many types of researche have been used these discriminating indices and reported various controversial results [36][37][38][39][40][41]. Given the availability of hemoglobin electrophoresis, these indices are not very imperative currently.…”