HbA_2筛查地中海贫血诊断界值的建立及其与MCV、MCH联合筛查的价值

Diagnostic cut-off value of HbA_2 for screening thalassemia and the combined determination of HbA_2,MCV and MCH

目的探讨血红蛋白(Hb)A_2与红细胞平均体积(MCV)、平均红细胞血红蛋白含量(MCH)筛查方案在地中海贫血(简称地贫)筛查中的应用价值。方法检测α-地贫、轻型β-地贫和体检健康者(健康对照组)HbA_2水平,比较3组HbA_2水平的变化。绘制受试者工作特征(ROC)曲线,评价HbA_2筛查地贫的性能。另外选取322例疑似地贫患者,用于筛查方案的性能评价。结果α-地贫组、轻型β-地贫组HbA_2水平与健康对照组比较,差异有统计学意义(P<0.05)。静止型α-地贫组、标准型α-地贫组、中间型α-地贫组之间及与健康对照组之间HbA_2水平差异均无统计学意义(P>0.05)。选用HbA_2<3.05%及HbA_2>3.90%分别作为筛查α-地贫及轻型β-地贫的诊断界值。MCV+MCH+HbA_2地贫筛查方案的敏感性、特异性、阳性预测值、阴性预测值、符合率分别为76.33%、58.82%、67.19%、69.23%和68.10%。结论 MCV<82.1 fL和(或)MCH<27.3 pg联合HbA_2<3.05%或HbA_2>3.90%筛查方案在地贫筛查中具有较好的性能,可用于大规模人群筛查,对于疑似α-地贫患者的诊断需结合相关辅助检查,或直接进行地贫基因检测。

Objective To study the role of hemoglobin(Hb) A2,mean corpuscular volume(MCV) and mean corpuscular hemoglobin(MCH) combined determination scheme for screening thalassemia. Methods The HbA2 levels of α-thalassemia group,light β-thalassemia group and healthy subjects(healthy control group) were determined,and the results were analyzed comparatively. The efficiency of HbA2 for screening thalassemia was evaluated by receiver operating characteristic(ROC) curve. The performance of the scheme was evaluated through screening 322 clinical suspected cases of thalassemia. Results The HbA2 levels in α-thalassemia group,light β-thalassemia group and healthy control group had statistical significance(P<0.05),but there was no statistical significance among stationary type,standard type and intermediate type α-thalassemia groups and healthy control group(P>0.05). The diagnostic cut-off values for screening α-thalassemia and light β-thalassemia were HbA2<3.05% and HbA2>3.90%,respectively. The sensitivity,specificity,positive predictive value,negative predictive value and consistency rate were 76.33%,58.82%,67.19%,69.23% and 68.10%,respectively. Conclusions The scheme, MCV<82.1 fL and(or) MCH<27.3 pg with HbA2<3.05% or HbA2>3.90%,has a good performance for screening thalassemia. It should carry on relevant auxiliary determination or detect thalassemia gene directly for suspected α-thalassemia patients.