Discriminant Red Cell Indices for Microcytic Hypochromic Anaemia in Distinguishing Beta Thalassaemia Trait and Iron Deficiency Anaemia: A Systematic Review

Abstract

Introduction: Numerous red cell indices are in practice for surveillance of Microcytic Hypochromic (MCHC) anaemia in determination of their aetiology to the Iron Deficiency Anaemia (IDA) and Beta Thalassaemia Trait (BTT). The studies have revealed that there exists the discrepancies for Sensitivity (SN) and Specificity (SP) for any single index conclusive to classify them to the categories of IDA and BTT. A comparative review is needed as to know which index is suitable to discriminate between above two major entities under MCHC anaemia, which can be put to the practice in resource poor laboratories. Aim: A systematic review was planned for diagnostic reliability of red cell indices that segregates IDA from BTT in a morphological classification of MCHC anaemia. Materials and Methods: A systematic literature search was conducted in a database that yielded 36 studies dealing with one or more of the five included indices (Mentzer index, Bessman index, Green and King index, Srivastava index and Sirdah index) in the present analysis. The data for SN and SP of these indices were collected and compared from their performance at discrimination between IDA and BTT and Youden index was calculated to compare the performance of individual index. Results: Of these five indices, the comparative statistics has shown Green and King index works well at the SN of 79.37% and SP of 82.54% as compared to the rest of the indices. The second closest index that is practicable at discriminating IDA from BTT is Mentzer index. Conclusion: None of the indices can be completely relied upon to achieve a conclusive segregation. However, Green and King and Mentzer indices can be used for screening the suspected population to identify patients which may need the specialised tests to confirm the diagnosis to bring this population under proper treatment either for IDA or BTT.