[Screening indices and their cut-off values for full-term neonates carrying β-thalassemia gene]

To investigate the screening indices and their cut-off values for full-term neonates carrying β-thalassemia gene.

A retrospective analysis was performed for the clinical data of 1 193 full-term neonates who underwent β-thalassemia screening (hemoglobin analysis with dried blood spots on neonatal heel blood filter paper and mutation detection of 17 β-globin genes). A multivariate logistic regression analysis was used to investigate the association between screening indices and β-thalassemia gene, and the receiver operating characteristic (ROC) curve was used to analyze the value of screening indices in determining the presence or absence of β-thalassemia gene.

Of the 1 193 neonates, 638 carried β-thalassemia gene. Of the 1 193 neonates, 637 (53.39%) had no HbA₂, among whom 310 carried β-thalassemia gene and 327 did not carry this gene; 556 (46.61%) had HbA₂, among whom 328 carried β-thalassemia gene and 228 did not carry this gene. As for the neonates without HbA₂, the β-thalassemia gene group had a significantly lower HbA level and a significantly higher HbF level than the β-thalassemia gene-negative group (P<0.01). As for the neonates with HbA₂, the β-thalassemia gene group had a significantly lower HbA level and significantly higher HbF and HbA₂/HbA ratio than the β-thalassemia gene-negative group (P<0.01). In the neonates without HbA₂, HbA, gestational age, and HbA combined with gestational age had an area under the ROC curve (AUC) of 0.865, 0.515, and 0.870, respectively, in determining the presence or absence of β-thalassemia gene (P<0.01), and HbA and HbA combined with gestational age had a similar AUC and a certain diagnostic value. In the neonates with HbA₂, HbA, HbA₂/HbA ratio, and HbA combined with HbA₂/HbA ratio had an AUC of 0.943, 0.885, and 0.978, respectively, in determining the presence or absence of β-thalassemia gene. The HbA combined with HbA₂/HbA ratio had the largest AUC. In the neonates without HbA₂, HbA had the largest AUC in determining the presence or absence of β-thalassemia gene at the cut-off value of 11.6%, with a sensitivity of 85.81% and a specificity of 79.82%. In the neonates with HbA₂, an HbA of 16.1%-22.0% and an HbA₂/HbA ratio of >1.4 had the largest AUC in determining the presence or absence of β-thalassemia gene, with a sensitivity of 91.38% and a specificity of 91.89%.

HbA and HbA₂/HbA ratio are effective indices for screening out full-term neonates carrying β-thalassemia gene.