Abstract

Circulating maternal levels of placental growth factor correlates well with placental function and numerous studies advocate its role to help rule-out preterm pre-eclampsia. A number of automated immunoassay platforms to quantify placental growth factors are currently available. The aim of this study was to highlight the importance of developing and validating appropriate reference ranges and clinical cut-offs for immunoassays, by comparing the results obtained from two different immunoassays of placental growth factor; the Quantikine^® ELISA and the automated Triage^® test. This was a secondary subgroup analysis of samples collected as part of a prospective cross-sectional study of placental growth factors in twin pregnancy. Consenting pregnant women with a twin pregnancy, across a variety of gestations, had a single blood sample taken at a one-time point only during their pregnancy. The plasma was initially biobanked and then later analysed in batches using both immunoassays. Although the placental growth factor values of the two immunoassays correlated well (r = 0.88, n = 178, p < .001), the actual results obtained were significantly different (mean difference 238.1 pg/ml). Poor concordance between the two immunoassays was also present, with the Triage^® test recording 36 cases as <100 pg/ml whereas the Quantikine^® ELISA identified only 4 as <100 pg/ml. Biomarker levels may vary significantly between different immunoassay platforms, highlighting the importance of developing validated clinical cut-offs for any automated immunoassay before its clinical application. These differences need to be understood to facilitate clinical utility given that placental growth factor testing is likely to be introduced into widespread clinical practice.

摘要

母体循环中的胎盘生长因子水平与胎盘功能密切相关，许多研究都提倡其有助于排除早产先兆子痫的作用。目前有许多用于量化胎盘生长因子的自动化免疫测定平台。本研究的目的是通过比较两种不同的胎盘生长因子免疫测定的结果，强调制定和验证免疫测定的适当参考范围和临床临界值的重要性；Quantikine ^® ELISA 和自动化 Triage ^®测试。这是对作为双胎妊娠胎盘生长因子前瞻性横断面研究的一部分收集的样本的二次亚组分析。同意怀孕的双胞胎孕妇，跨越不同的妊娠期，仅在怀孕期间的一个时间点采集一次血样。血浆最初是生物库，然后使用两种免疫测定法分批分析。尽管两种免疫测定的胎盘生长因子值相关性很好（r  = 0.88，n  = 178，p  < .001），但获得的实际结果有显着差异（平均差异 238.1 pg/ml）。两种免疫测定之间的一致性也很差，Triage ^®测试记录了 36 例<100 pg/ml，而 Quantikine ^® ELISA 仅确定 4 例 <100 pg/ml。不同免疫测定平台之间的生物标志物水平可能存在显着差异，突出了在临床应用之前为任何自动免疫测定开发经过验证的临床临界值的重要性。鉴于胎盘生长因子测试很可能被引入广泛的临床实践，因此需要了解这些差异以促进临床应用。