Patra index and Mentzer index - A retrospective comparative study to differentiate Beta-Thalassemia Trait from iron deficiency anemia.

Introduction: Beta-thalassemia trait (BTT) and iron deficiency anemia (IDA) are the two most common causes of microcytic hypochromic anemia. Differentiating these conditions is crucial, particularly in school-aged children, to reduce the societal burden of anemia. Red cell indices and formulas derived from red blood cell (RBC) parameters provide simple, rapid, and cost-effective diagnostic tools. While these indices are primarily used in pediatric populations, they can also aid in diagnosing microcytic anemia in adults. Methodology: This cross-sectional observational study was conducted in the Department of Pathology, Rajendra Institute of Medical Sciences (RIMS), Ranchi, from May 1, 2016, to April 30, 2017. A total of 406 patients (190 males and 216 females), aged 3-50 years, with microcytic hypochromic anemia, were randomly selected. The diagnostic performance of the Mentzer index (mean corpuscular volume (MCV)/RBC count) and the Patra index (MCV/red cell distribution width (RDW)) was evaluated based on sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), efficiency, and Youden's index. Results: The Patra index demonstrated superior diagnostic accuracy, with a sensitivity of 88.23%, specificity of 99.7%, and Youden's index of 87.93%. This index proved to be a more reliable tool for differentiating BTT from IDA than the Mentzer index. Conclusion: Given its high sensitivity, specificity, and affordability, the Patra index is an effective screening tool for primary care physicians, particularly in resource-limited settings. Its low cost and ease of sample transport make it a valuable method for initial screening, with positive cases confirmed by high-performance liquid chromatography (HPLC) using the same EDTA-anticoagulated blood sample.