Evaluation of Applying a Combination of Red Cell Indexes and Formulas to Differentiate β-Thalassemia Trait from Iron Deficiency Anemia in the Thai Population

A novel discriminant algorithm for differential diagnosis of mild to moderate thalassemia and iron deficiency anemia

BACKGROUND

Mild to moderate thalassemia trait (TT) and iron deficiency anemia (IDA) are the most common conditions of microcytic hypochromic anemia (MHA) and they exhibit highly similar clinical and laboratory features. It is sometimes difficult to make a differential diagnosis between TT and IDA in clinical practice. Therefore, a simple, effective, and reliable index is needed to discriminate between TT and IDA.

METHODS

Data of 598 patients (320 for TT and 278 for IDA) were enrolled and randomly assigned to training set (278 of 598, 70%) and validation set (320 of 598, 30%). Stepwise discriminant analysis was used to define the best diagnostic formula for the discrimination between TT and IDA in training set. The accuracy and diagnostic performance of formula was tested and verified by receiver operating characteristic (ROC) analysis in validation set and its diagnostic performance was compared with other published indices.

RESULTS

A novel formula, Thalassemia and IDA Discrimination Index (TIDI) = -13.932 + 0.434 × RBC + 0.033 × Hb + 0.025 ×MCHC + 53.593 × RET%, was developed to discriminate TT from IDA. TIDI showed a high discrimination performance in ROC analysis, with the Area Under the Curve (AUC) = 0.936, Youden' s index = 78.7%, sensitivity = 89.5%, specificity = 89.2%, respectively. Furthermore, the formula index also obtained a good classification performance in distinguishing 5 common genotypes of TT from IDA (AUC from 0.854-0.987).

CONCLUSION

The new, simple algorithm can be used as an effective and robust tool for the differential diagnosis of mild to moderate TT and IDA in Guangxi region, China.

Cord Blood Hematological Parameters of Fetuses Detected Different Thalassemia Genotypes in the Second Trimester of Pregnancy

Background

Hemoglobinopathies are the most common inherited diseases in humans resulting from impaired globin chain synthesis of hemoglobin. The progression of thalassemia rates is prevented with prenatal screening methods.

Aims

To evaluate the hematological parameters of α- and β-thalassemia and normal fetuses aged 17-25 weeks of gestation.

Study Design

A cross-sectional study.

Methods

Pregnant women who underwent cordocentesis in the second trimester because of the risk of having a baby with thalassemia were included in the study. Hematological indices and molecular DNA methods were analyzed from the cord blood samples of 129 women who were 17-25 weeks into pregnancy. The HPLC method was used for Hb fraction analysis. Amplification refractory mutation system, restriction enzyme analysis, multiplex polymerase chain reaction, and sequencing methods were used for the molecular analysis. Maternal contamination was eliminated by the short tandem repeat method.

Results

In total, 112 of the fetuses carry α- and β-thalassemia heterozygous or homozygous (α: 37, β: 58, mixed: 17) and 17 fetuses had a normal genotype for thalassemia. Significant differences in adult hemoglobin (HbA), fetal hemoglobin (HbF), Hb Barts, MCV, MCH, and RDW were detected in three groups compared with the normal group (p < 0.001, except for RBC, Hb, HCT, and MCHC). Differences in HbF, Hb Barts, MCV, MCH, and RDW were observed in the α-thalassemia groups compared with the normal group (p < 0.001). Among the five β-thalassemia subgroups, only HbA and RDW were different from the normal group (p < 0.001).

Conclusion

This study could be a good reference for future studies and prenatal diagnostic applications in emphasizing the importance of changes in the blood parameters of fetuses before molecular genotyping. These hematological data give valuable information to clinicians about the fetus to enlighten families in making appropriate decisions during prenatal diagnosis.

Dietary Iron Intake and Availability in Hill Tribe and Urban Women, Chiang Rai Province, Northern Thailand

Data were collected as part of a cross-sectional study. The objectives were to compare dietary intakes of iron and enhancers and inhibitors of non-heme iron absorption in hill tribe and urban women of Chiang Rai province, northern Thailand, and compare iron- and vitamin C- containing foods sold in markets in both settings. Dietary data were collected using three 24- hour recalls from 128 women aged 19-50 years (hill tribe: n = 65; urban n = 63), and proportions of low-, medium- and high-iron/vitamin C containing foods were surveyed in local markets. Hill tribe women consumed less iron, animal protein, vitamin C and calcium, but market availability of iron/vitamin C foods was similar. Future interventions should focus on food choice modification, to improve intakes of iron and foods that enhance its absorption, especially among hill tribe women.

Hemoglobin disorders: lentiviral gene therapy in the starting blocks to enter clinical practice

The β-hemoglobinopathies, transfusion-dependent β-thalassemia and sickle cell disease, are the most prevalent inherited disorders worldwide and affect millions of people. Many of these patients have a shortened life expectancy and suffer from severe morbidity despite supportive therapies, which impose an enormous financial burden to societies. The only available curative therapy is allogeneic hematopoietic stem cell transplantation, although most patients do not have an HLA-matched sibling donor, and those who do still risk life-threatening complications. Therefore, gene therapy by one-time ex vivo modification of hematopoietic stem cells followed by autologous engraftment is an attractive new therapeutic modality. The first proof-of-principle of conversion to transfusion independence by means of a lentiviral vector expressing a marked and anti-sickling β^T87Q-globin gene variant was reported a decade ago in a patient with transfusion-dependent β-thalassemia. In follow-up multicenter Phase II trials with an essentially identical vector (termed LentiGlobin BB305) and protocol, 12 of the 13 patients with a non-β⁰/β⁰ genotype, representing more than half of all transfusion-dependent β-thalassemia cases worldwide, stopped red blood cell transfusions with total hemoglobin levels in blood approaching normal values. Correction of biological markers of dyserythropoiesis was achieved in evaluated patients. In nine patients with β⁰/β⁰ transfusion-dependent β-thalassemia or equivalent severity (β^IVS1-110), median annualized transfusion volume decreased by 73% and red blood cell transfusions were stopped in three patients. Proof-of-principle of therapeutic efficacy in the first patient with sickle cell disease was also reported with LentiGlobin BB305. Encouraging results were presented in children with transfusion-dependent β-thalassemia in another trial with the GLOBE lentiviral vector and several other gene therapy trials are currently open for both transfusion-dependent β-thalassemia and sickle cell disease. Phase III trials are now under way and should help to determine benefit/risk/cost ratios to move gene therapy toward clinical practice.

Should sex differences be considered when applying mathematical indices and formulas for discriminating β- thalassemia minor from iron deficiency?

Background

β-thalassemia minor (BTM) and iron deficiency (ID) are common disorders characterized by microcytosis and/or hypochromasia, leading to a challenge in their discrimination during mass-screening programs especially in developing countries where resources are limited. It has been shown with varying reliability that quick exclusion of either disorder could be achieved mathematically using RBC-based indices and formulas. However, none of these proposed indices and formulas considered the sex-based hematological differences. This comparative retrospective study examined the efficacy of using sex-based RBC indices in the mathematical discrimination BTM and ID in adult males and females.

Methods

The CBC of randomly selected eight hundred adults diagnosed with BTM or ID (200M & 200F BTM, and 200M & 200F ID) were used in the comparisons. The discrimination power, in terms of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and Youden index were calculated for all subjects and separately for males and females for 20 mathematical indices and formulas.

Results

Data revealed significant differences in the RBC-based indices between males and females for both BTM and ID groups. Significant variation in reliability indicators for the different indices and formulas were discovered between males and females samples.

Conclusion

Sex-based indices and formulas are necessary to improve the reliability in mathematically discriminating between BTM and ID in mass screening programs. We also advocate for a large–scale multicenter study to establish the parameters of such indices and formulas with sex and age.