Yeo G S, Tan K H, Liu T C
Department of Maternal-Fetal Medicine, Kandang Kerbau Hospital, Singapore.
Singapore Med J. 1995 Dec;36(6):615-8.
The mean red cell volume (MCV) has been shown to be useful in a 2-stage screening process for beta-thalassaemia traits among pregnant women though associated with a large number of false positive results. We tested prospectively the ability of 5 discriminant functions (DF), (England & Fraser, Shine & Lal, Mentzer, Srivistava and Klee et al) to reduce the number of false positives when used as additional screening determinants for beta-thalassaemia in antenatal patients with red cell microcytosis.
The diagnostic performance of each DF was compared in 493 patients with microcytosis and known beta-thalassaemia status. Truth table analysis and Receiver Operation Characteristic curves for each function were determined.
11.4% of the patients with microcytosis were diagnosed to have beta-thalassaemia traits. DFs incorporating the red cell indices: haemoglobin or total red cell count are unsuitable during pregnancy. Shine & Lal's index [(0.01 x MCH x (< MCV)2] reduced the number of people recalled for confirmatory testing by 31.1% and increased the diagnostic yield to 38.7% while maintaining a negative predictive value for the test of 0.993.
We conclude that a 3-stage screening process for beta-thalassaemia among pregnant women in Singapore involving the MCV, Shine & Lal's index and a confirmatory test to be both valid and cost-effective.
平均红细胞体积（MCV）已被证明在孕妇β地中海贫血特征的两阶段筛查过程中有用，尽管会产生大量假阳性结果。我们前瞻性地测试了5种判别函数（DF）（英格兰与弗雷泽法、沙恩与拉尔法、门泽法、斯里瓦斯塔法和克莱等人的方法）在作为红细胞小红细胞症产前患者β地中海贫血的额外筛查决定因素时减少假阳性数量的能力。
比较了493例已知β地中海贫血状态的小红细胞症患者中每种DF的诊断性能。确定了每个函数的真值表分析和受试者工作特征曲线。
11.4%的小红细胞症患者被诊断为具有β地中海贫血特征。纳入红细胞指数（血红蛋白或总红细胞计数）的DF在孕期不适用。沙恩与拉尔指数[（0.01×平均红细胞血红蛋白含量×（<平均红细胞体积）²]将召回进行确诊检测的人数减少了31.1%，并将诊断率提高到38.7%，同时保持检测的阴性预测值为0.993。
我们得出结论，新加坡孕妇β地中海贫血的三阶段筛查过程，包括MCV、沙恩与拉尔指数以及确诊检测，既有效又具有成本效益。
