Discrimination indices as screening tests for beta-thalassemic trait.

Area of Science:

• Hematology
• Clinical Diagnostics
• Medical Laboratory Science

Background:

• Beta-thalassemic trait (beta-TT) and iron deficiency anemia (IDA) are common microcytic anemias requiring accurate differentiation.
• Electronic cell counters provide red blood cell (RBC) indices crucial for distinguishing these anemias.

Purpose of the Study:

• To evaluate the diagnostic accuracy of six established indices in differentiating between IDA and beta-TT.
• To assess the sensitivity, specificity, and overall reliability of these indices.

Main Methods:

• Calculated six discrimination indices: Mentzer Index (MI), Green & King Index (G&K), RDW Index (RDWI), England & Fraser Index (E&F), RDW, and RBC count.
• Analyzed data from 373 patients with beta-TT and 120 patients with IDA.
• Determined sensitivity, specificity, positive and negative prognostic values, efficiency, and Youden's index (YI) for each index.

Main Results:

• The Green & King (G&K) index demonstrated the highest reliability, followed by E&F, RBC count, MI, and RDWI.
• The RDW index failed to differentiate between IDA and beta-TT.
• G&K showed the highest sensitivity (75.06%), efficiency (80.12%), and YI (70.86%) for beta-TT detection.

Conclusions:

• The evaluated indices, including G&K, lack sufficient sensitivity for reliably diagnosing beta-TT and cannot be solely relied upon for differential diagnosis.
• These indices exhibit high specificity but are not suitable as screening tools for beta-TT due to a significant risk of false negatives.