Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
J Obstet Gynaecol Res. 2020 May;46(5):774-778. doi: 10.1111/jog.14222. Epub 2020 Feb 19.
To identify the optimal cutoff of mean corpuscular volume (MCV) for screening of alpha-thalassemia 1 trait.
The database of pregnant women who attended antenatal care clinic at Department of Obstetrics and Gynecology, Chiang Mai University during January 1st, 2015 to December 31st, 2017 was accessed and reviewed. A total of 1264 cases who had MCV ≤80 fL and met the inclusion criteria were enrolled to the study. Cases with hemoglobin level ≤10.0 gm/dL, iron deficiency anemia, chronic medical diseases and other types of thalassemia trait except alpha-thalassemia 1 trait were excluded.
After exclusion, 438 cases were available for analysis. Of them, 139 were alpha-thalassemia 1 trait. Based on the receiver operating characteristic curves, the best cutoff value of MCV for screening of alpha-thalassemia 1 trait was ≤76.15 fL, giving 100% sensitivity, and 60.9% specificity with the area under curve of 0.925. Compared to the conventional cutoff (≤80 fL), the new cutoff gave much less false positive tests (117 vs 299 cases), whereas capability to detect alpha-thalassemia 1 trait was the same.
With the new MCV cutoff (≤76.15 fL) as a secondary cutoff for screening alpha-thalassemia 1 carrier, a substantial number of positive cases requiring DNA analysis could be avoided without compromising the detection efficacy.
确定平均红细胞体积（MCV）的最佳截断值，以筛查α-地中海贫血 1 型。
检索并回顾了 2015 年 1 月 1 日至 2017 年 12 月 31 日期间在清迈大学妇产科产前保健诊所就诊的孕妇数据库。共纳入 1264 例 MCV≤80 fL 且符合纳入标准的病例进行研究。排除血红蛋白水平≤10.0 gm/dL、缺铁性贫血、慢性疾病和其他类型的地中海贫血，除外α-地中海贫血 1 型。
排除后，438 例可用于分析。其中，139 例为α-地中海贫血 1 型。基于受试者工作特征曲线，MCV 筛查α-地中海贫血 1 型的最佳截断值为≤76.15 fL，灵敏度为 100%，特异性为 60.9%，曲线下面积为 0.925。与传统截断值（≤80 fL）相比，新截断值假阳性试验明显减少（117 例与 299 例），而检测α-地中海贫血 1 型的能力相同。
使用新的 MCV 截断值（≤76.15 fL）作为筛查α-地中海贫血 1 型携带者的次要截断值，可以避免大量需要 DNA 分析的阳性病例，而不会影响检测效果。
