California Department of Public Health, Richmond, CA, USA.
Obstet Gynecol. 2012 Apr;119(4):785-94. doi: 10.1097/AOG.0b013e31824be8f5.
Nuchal translucency medians are used to convert nuchal translucency measurements to multiple of the median values for use in risk assessment. There has been much debate about the use of practitioner-specific medians instead of population-based medians to correct for practitioner bias. This study examined data from the California Prenatal Screening Program to evaluate the effect of individual medians on screening performance.
For this retrospective study, we identified first-trimester specimens in the California Prenatal Screening Program database for which screening results were calculated using a practitioner-specific median (n=55,286) and recalculated risk assessment using a population-based median. We looked at positive rates for Down syndrome and Trisomy 18 as well as overall screening results. We also looked at the recalculated risks for cases in which there has been a positive diagnosis of a chromosomal abnormality to determine if cases would have been missed if practitioner-specific medians had not been used.
Nuchal translucency multiples of the median would be lower for the majority of nuchal translucency practitioners if a population-based median were used instead of practitioner-specific medians. Outcomes data from the California Prenatal Screening Program's database indicate that 14 positively diagnosed cases would have been missed by the screening program if population-based medians had been used.
The use of practitioner-specific medians corrects for practitioner bias in measuring nuchal translucency. Practitioner-specific medians improve screening performance and help meet detection rate goals.
II.
颈项透明层中位数用于将颈项透明层测量值转换为中位数的倍数，以便用于风险评估。关于使用特定于从业者的中位数而不是基于人群的中位数来纠正从业者偏差，已经有很多争论。本研究通过加州产前筛查计划的数据来评估个体中位数对筛查性能的影响。
在这项回顾性研究中，我们从加州产前筛查计划数据库中确定了在第一孕期进行的标本，这些标本的筛查结果是使用特定于从业者的中位数计算的（n=55286），并使用基于人群的中位数重新计算风险评估。我们观察了唐氏综合征和 18 三体的阳性率以及整体筛查结果。我们还观察了在有染色体异常阳性诊断的情况下重新计算的风险，以确定如果不使用特定于从业者的中位数，是否会错过病例。
如果使用基于人群的中位数而不是特定于从业者的中位数，大多数颈项透明层从业者的颈项透明层中位数倍数将会降低。来自加州产前筛查计划数据库的结果数据表明，如果使用基于人群的中位数，该筛查计划将错过 14 例阳性诊断病例。
使用特定于从业者的中位数可以纠正测量颈项透明层时的从业者偏差。特定于从业者的中位数可提高筛查性能并有助于达到检测率目标。
II。
