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

OBJECTIVE

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

METHODS

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.

RESULTS

Of the 1 193 neonates, 638 carried β-thalassemia gene. Of the 1 193 neonates, 637 (53.39%) had no HbA, among whom 310 carried β-thalassemia gene and 327 did not carry this gene; 556 (46.61%) had HbA, among whom 328 carried β-thalassemia gene and 228 did not carry this gene. As for the neonates without HbA, 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 HbA, the β-thalassemia gene group had a significantly lower HbA level and significantly higher HbF and HbA/HbA ratio than the β-thalassemia gene-negative group (P<0.01). In the neonates without HbA, 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 HbA, HbA, HbA/HbA ratio, and HbA combined with HbA/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 HbA/HbA ratio had the largest AUC. In the neonates without HbA, 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 HbA, an HbA of 16.1%-22.0% and an HbA/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%.

CONCLUSIONS

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