唐氏综合征血清学产前筛查方案优化的研究
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摘要
第一部分唐氏综合征中孕期血清学酌情三联产前筛查方案的可行性研究
1.研究背景
在唐氏综合征(DS)中孕期血清学产前筛查方案中,三联(AFP+freeβ-hCG+uE3)产前筛查(简称三联筛查)比二联(AFP+freeβ-hCG)产前筛查(简称二联筛查)检出率高。但作为群体性预防措施,产前筛查在追求高检出率和低漏检率的同时,必须考察筛查方案的社会成本效益。与二联筛查相比,三联筛查方案增加了指标uE3的检测虽然可提高DS检出率,但也使筛查费用大幅增加。并且,同时值得注意的是：uE3在DS产前筛查风险率计算公式中的权重有限,增加uE3检测的三联筛查方案对风险率极低(小于1／1000)的二联筛查阴性病例和风险率高(大于或等于1／270)的二联筛查阳性病例的结果发挥影响的可能性较小。因而,有选择的进行三联筛查是一个值得探讨的问题。
为了在我国现行中孕期二联筛查的基础上进一步提高DS产前筛查检出率,同时又兼顾我国国情和筛查方案的社会成本效益,我们提出中孕期血清学“酌情三联产前筛查”(简称酌情三联筛查)方案,即以二联筛查为初筛方案,有选择的对部分二联筛查阴性病例进一步检测uE3行三联筛查,以期提高筛查检出率的同时降低医疗成本。
2.研究目的
1)分析中孕期唐氏综合征血清学二联筛查假阴性病例的筛查风险率区间,论证对部分二联筛查阴性病例(风险率在1／1000-1／270区间)加做uE3行三联筛查(酌情三联筛查)的意义；
2)比较酌情三联筛查和二联筛查的检出率和假阳性率,评估酌情三联筛查的效率；
3)比较酌情三联筛查和三联筛查的成本支出,评估酌情三联筛查的成本效益。
3.研究方法
收集孕15-20周中孕期二联筛查假阴性的孕妇资料共30例,其中有24例二联筛查风险率位于1／1000-1／270区间,定义为二联筛查假阴性组；随机抽取322例同时期中孕期二联筛查风险率位于1／1000-1／270区间的二联筛查真阴性的孕妇资料作为对照,定义为二联筛查真阴性组。用时间分辨荧光免疫分析技术测定两组间血清uE3水平并重新计算DS妊娠风险率,以1／270为切割值,判定三联筛查结果。结合文献报道的中国人群二联筛查和三联筛查的检出率和假阳性率,计算酌情三联筛查方案的检出率、假阳性率和经济支出情况,评价其相对于二联筛查和三联筛查方案的临床应用价值。
4.结果
本研究发现：80%的二联筛查假阴性病例其二联筛查风险率位于1／1000-1／270区间；经酌情三联筛查,6例二联筛查假阴性病例和3例二联筛查真阴性病例转变为筛查阳性。与二联筛查方案比较,酌情三联筛查方案可以在不增加假阳性率的基础上将DS妊娠的检出率提高10%。与三联筛查方案比较,酌情三联筛查方案可以减少84.3%以上的uE3检测相关的费用支出。
5.结论
对风险率为1／1000-1／270的二联筛查阴性孕妇再检测血清uE3水平以进一步评估DS妊娠风险率的酌情三联筛查方案,既能提高原二联筛查的检出率,又能较常规三联筛查节约成本,可能是适合我国国情的唐氏综合征血清学筛查策略,同时也值得其它发展中国家借鉴。
本部分研究通过对大样本的少见而且收集难度大的二联筛查假阴性病例的回顾性研究,首创“酌情三联筛查”的概念,有助于国家现行DS产前筛查策略的改进,研究结果已发表于《Prenatal Diagnosis》。
第二部分正常双胎妊娠与单胎妊娠中孕期孕妇血清freeβ-hCG和AFP水平的比较研究
1.研究背景
随着辅助生育技术的开展及孕妇年龄高龄化,近年来双胎妊娠发生率呈现升高趋势。由于我国人口基数大,双胎妊娠孕妇已是不容忽视的一个庞大的群体。并且,双胎妊娠中至少一胎为染色体异常的发生率较同年龄组单胎妊娠高,所以很有必要开展对双胎妊娠孕妇唐氏综合征(DS)的产前筛查。然而,双胎妊娠DS产前筛查至今是该领域的一个盲区。有报道认为,早孕期胎儿颈部透明带(NT)测定对双胎妊娠DS筛查的价值较大,但NT技术要求高、检测通量小且我国医疗资源有限,普及难度大。虽然血清学产前筛查方案在双胎妊娠中的应用价值一直备受争议,但原因之一可能是由于以单胎妊娠孕妇参数建立的双胎妊娠产前筛查方案欠合理。目前国外有关双胎妊娠孕妇联合freeβ-hCG和AFP的中孕期血清学二联筛查的资料很少,而国内更是缺乏大样本系统研究。通过建立双胎妊娠特异性的孕妇血清标志物参考值范围来完善我国双胎妊娠血清学二联筛查方案,有可能成为我国双胎妊娠DS产前筛查的一条出路。
2.研究目的
本研究旨在1)探讨双胎妊娠孕妇中孕期血清学二联筛查时孕妇血清freeβ-hCG和AFP变化规律；2)明确单胎妊娠与双胎妊娠孕妇血清free p-hCG和AFP水平是否存在差异和相关性。
3.方法
收集孕15～20周双胎妊娠孕妇456例为研究组,随机选择同时期单胎妊娠孕妇12,067例作为对照组；用时间分辨荧光免疫分析技术测定两组孕妇血清freeβ-hCG和AFP浓度,观察中孕期双胎妊娠和单胎妊娠孕妇上述血清标志物的变化特点,比较各孕周两组间freeβ-hCG和AFP水平的差异及相关性。
4.结果
所有病例经随访确定为非唐氏综合征妊娠。从孕15周到孕20周,单胎组孕妇血清freeβ-hCG水平逐渐降低,而双胎组孕妇血清freeβ-hCG水平呈波浪状下降；双胎妊娠组freeβ-hCG水平与单胎妊娠组的两倍值在孕16、17和19周有显著性差异(P均＜0.05)。从孕15周到20周,单胎组孕妇血清AFP水平逐渐升高,而双胎组孕妇血清AFP水平呈波浪状上升；双胎妊娠组AFP水平与单胎妊娠组的两倍值在孕16周和19周有显著性差异(P均＜0.05)。单胎组绝大多数孕周孕妇血清freeβ-hCG和AFP水平与体重相关；而双胎组绝大多数孕周孕妇血清freeβ-hCG和AFP水平与体重没有显著性相关。
5.结论
双胎妊娠孕妇血清freeβ-hCG和AFP水平与单胎妊娠数值间不存在固定的两倍关系,且与孕妇体重间不存在稳定的相关性,双胎妊娠孕妇血清二联筛查不宜参照单胎模式,而应以双胎妊娠孕妇血清freeβ-hCG和AFP水平及体重参考值建立其特异性DS产前筛查模式。
本部分研究在长期原始数据积累和大样本统计分析的基础上,提出根据双胎妊娠筛查指标参考值建立双胎血清学筛查模式并创建了部分双胎妊娠筛查指标数据资料,填补了国内空白。研究结果已发表于《Prenatal Diagnosis》。
第三部分中国人群早孕期孕妇血清freeβ-hCG、PAPP-A和ADAM 12水平变化
1.研究背景
唐氏综合征(DS)早孕期产前筛查在我国尚未大规模开展,但这无疑是今后DS产前筛查工作的发展趋势。国外报道,结合freeβ-hCG、PAPP-A和胎儿颈部透明带(NT)的早孕期联合筛查方案是最佳方案；但NT测定技术要求高、检测通量小,受限于医疗资源而不易临床普及。去整合素金属蛋白酶12(ADAM 12)是新近发现的一个高效的早孕期DS筛查血清标志物,有望替代NT提高早孕期DS产前筛查效率。探讨通量较大且不受超声检测能力所限的早孕期产前筛查方案有助于早孕期产前筛查的开展。目前少见早孕期freeβ-hCG和PAPP-A在大样本中国人群中的研究报道,更罕见ADAM 12的相关报告。
2.研究目的
探索中国孕妇早孕期血清freeβ-hCG、PAPP-A和ADAM 12水平的变化规律及相关性,为建立中国孕妇早孕期血清学DS产前筛查方案提供理论依据。
3.方法
收集2007年7月～2010年2月间在浙江大学医学院附属妇产科医院行早孕期(孕7-13周)检查的单胎妊娠孕妇资料685例,其中1例为DS妊娠；用时间分辨荧光免疫分析技术测定孕妇血清freeβ-hCG、PAPP-A和ADAM 12水平,统计分析各标志物与体重、孕周的关系及各标志物之间的相关性。
4.结果
从孕≦9周到孕13周,非DS妊娠孕妇血清PAPP-A浓度中位数分别为876.00、1365.00、2380.00、3995.00和5305.00 mU／L,ADAM 12浓度中位数分别为282.55、376.80、436.36、547.43和634.08 ng／ml,两者水平均随孕周的增加而增高；freeβ-hCG浓度中位数分别为87.30、86.45、70.40、59.45和42.10 ng／ml,其水平在孕9～10周基本稳定在一个平台,孕10周后迅速下降。各血清标志物与孕周和孕妇体重之间均存在相关性(P均＜0.01)。PAPP-A和ADAM 12之间存在相关性(P＜0.01),而freeβ-hCG与PAPP-A及ADAM 12均无相关性(P均＞0.01)。与非DS妊娠孕妇血清标志物浓度中位数比较,DS妊娠孕妇freeβ-hCG水平升高,PAPP-A和ADAM 12水平降低。
5.结论
我国人群早孕期孕妇血清PAPP-A和ADAM 12水平均随孕周的增加而增高,freeβ-hCG水平于孕10周后明显下降。早孕期孕妇血清ADAM 12与PAPP-A有相关性,两者联合应用的效价有待进一步探讨。
本部分研究验证了我国人群早孕期孕妇血清PAPP-A和freeβ-hCG变化趋势,提出AMAM 12可能不是一个独立的DS早孕期产前筛查指标,为我国早孕期产前筛查方案的探索和建立提供了理论依据。
Chapter One Contingent triple-screening for Down syndrome in the second trimester:a feasibility study in Mainland Chinese population
1. Background
The detection rate of second trimester maternal serum triple-screening (AFP+freeβ-hCG+uE3) program is higher than that of double-screening (AFP+freeβ-hCG). But the costs for triple-screening increased too due to one more detection index added in. In order to improve the detection rate of Down syndrome and reduce the costs just based on current routine double-screening program in China, and taking into account of the actual situation of Chinese economy& technology and the cost-effectiveness of program, we proposed a contingent triple-screening program, which performing triple-screening in pregnant women with DS risks between 1/270 and 1/1000 at routine double-screening.
2. Objectives
This study was designed for the following purposes:(1) to determine whether the DS risks between 1/270 and 1/1000 at routine double-screening is a feasible range of contingent triple-screening program; (2) to explore the efficacy of contingent triple-screening compared with routine double-screening in the second trimester; (3) to evaluate the economic value of the contingent triple-screening compared with routine triple-screening in the second trimester.
3. Methods
30 maternal serum samples of double-screening false-negative cases were collected and 24 of them had DS risks between 1/270 and 1/1000 at routine double-screening. Maternal serum concentrations of AFP, free P-hCG and uE3 were measured by time-resolved fluoroimmunoassay in 24 double-screening false-negative (DSFN) and 322 double-screening true-negative (DSTN) pregnancies with DS risks between 1/1000- 1/270 at routine double-screening performed at 15-20 weeks of gestation. DS risk of each pregnancy was calculated by computer software. The detection rate (DR), false positive rate (FPR), and costs of contingent triple-screening were calculated and compared to routine double-screening and triple-screening methods.
4. Results
80% double-screening false-negative cases had DS risks between 1/270 and 1/1000 at routine double-screening.6 of 24 DSFN and 3 of 322 DSTN were contingent triple-screening positive. Compared to routine double-screening, DR of contingent triple-screening increased by 10%(from 50% to 60%) without a significant increase of FPR (p>0.05). When compared to routine triple-screening, uE3 costs in contingent triple-screening were reduced by more than 84.3%.
5. Conclusions
Second trimester maternal serum contingent triple-screening could not only improve the efficacy of screening but also reduce the health care costs. It could be effective and suitable for prenatal care in Mainland China. Governments and Health Agencies of other developing countries may also find this strategy cost-effective.
This was the first introduction of the concept of "contingent triple-screening program" in the world. Our results has been published in'Prenatal Diagnosis'(Prenat Diagn.2010 Jan; 30(1):74-6.), a core journal in the field of prenatal care.
Chapter Two Second-trimester maternal serum free-β-human chorionic gonadotropin and a-fetoprotein levels in normal twin and singleton pregnancies
1. Background
Twin pregnancies are frequent in China and the incidence of having at least one Down Syndrome (DS)-affected fetus in twin pregnancies was higher than that of singleton pregnancies, thus it is important to carry out prenatal screening for twin pregnancies. However, the value of maternal serum screening in twin pregnancies is still controversial. In current prenatal screening for twin pregnancies, the estimated risk of DS in twin pregnancies was calculated based on the theory that maternal serum concentration of markers in twins would be twice of that in singletons. We may suggest that the current maternal serum screening programs, which are based on the data collected from singleton pregnancies seem to be unreasonable for DS screening in twin pregnancies. It is necessary to establish special gestational age-specific mid-trimester normal medians of maternal serum freeβ-hCG and AFP for DS screening in twin pregnancies.
2. Objectives
The study was designed to explore the changing trends of the levels of maternal serum freeβ-hCG and AFP used in second-trimester DS screening for twin pregnancies. And to confirm whether there are differences between Chinese normal twin and singleton pregnancies in the levels of maternal serum freeβ-hCG and AFP.
3. Methods
The concentrations of maternal serum markers of 456 twin pregnancies and 12,067 singleton controls in gestational 15 to 20 weeks were measured by time-resolved fluoroimmunoassay, and the levels of markers were compared between the twins and singletons in each gestational week.
4. Results
All cases had been followed-up till 1 month after childbirth and no childbirth with DS was found. Significant differences were found between the levels of freeβ-hCG in twins and twice of those in singletons in 16,17 and 19 gestational weeks (p< 0.05 for all). While considering AFP, significant differences were found in 16 and 19 gestational weeks (p< 0.05 for both). In singleton pregnancies there were significant correlations between the levels of makers and maternal weights in most gestational week, while no correlations were found in twins between the levels of markers and maternal weights in most gestational weeks.
5. Conclusions
The Chinese gestational age-specific levels of maternal serum markers in normal twins are not twice as those in singletons. The current weight-correction model for DS screening may be not feasible for twins. It is necessary to establish special gestational age specific mid-trimester normal medians of the freeβ-hCG and AFP and special weight-correction model for DS screening in twin pregnancies. Our study for medians of freeβ-hCG and AFP in Chinese twin pregnancies will help to establish specific second trimester DS screening model for Chinese twin-prenatal care and the results has been published in'Prenatal Diagnosis'(Prenat Diagn.2008 Aug; 28(8):735-8.), a core journal in the field of prenatal care.
Chapter Three Maternal serum freeβ-hCG, PAPP-A, and ADAM 12 levels in local Chinese population during the first trimester
1. Background
First trimester prenatal screening has not yet carried out widespread in China, but it is undoubtedly the tendency of the future clinical work with prenatal screening. So, it is necessary to gradually carry out basic research related to first trimester screening. Among all screening programs in first trimester, the combined screening (Freeβ-hCG+PAPP-A+NT) is the best. But NT measurement is so difficult and it couldn't be performed as a routine screening program in current China. A Disintegrin and Metalloproteinase 12 (ADAM 12) is a recently discovered new serum marker, which is considered increasing the detection rate of DS screening significantly. It is rarely reported about freeβ-hCG, PAPP-A and ADAM 12 in the Chinese population of large sample study of first trimester pregnancy.
2. Objectives
To explore maternal serum freeβ-hCG, PAPP-A and ADAM 12 levels in the first trimester in local Chinese population, in order to provide a theoretical basis for establishment of first trimester screening program in local Chinese pregnant women.
3. Methods
From July 2007 to February 2010,685 maternal serum samples(1 DS pregnancy and 684 non-DS pregnancies) were collected from women with singleton pregnancy who received first trimester (7-13 gestational weeks) examination in the Affiliated Women's Hospital, College of Medicine, Zhejiang University. Levels of freeβ-hCG, PAPP-A and ADAM 12 were measured by commercial time-resolved fluoroimmunoassay. Statistical analysis was performed using SPSS 16.0 software to evaluate the relationship between each serum marker and weight, gestational age, and the correlations between markers were analyzed too.
4. Results
After statistical analysis, there was no significant differences were found between the maternal ages and weights in each gestational week, and no correlations were found between the maternal weights and gestational weeks either (P>0.01 for all). From 9th gestational week to 13th gestational week, the median of maternal serum PAPP-A concentration in non-DS was 876.00,1365.00,2380.00,3995.00 and 5305.00 mU/L respectively. While the median of maternal serum ADAM 12 concentration in non-DS was 282.55,376.80,436.36,547.43 and 634.08 ng/ml respectively.The concentrations of both serum markers above were increased with the gestational weeks increased. The median of maternal serum freeβ-hCG concentration in non-DS was 87.30,86.45,70.40, 59.45 and 42.10 ng/ml respectively, and it was significantly decreased after 10 gestational weeks. Relationship could be found between each serum marker and gestational weeks, maternal weights (P<0.01 for all), and correlation could be found between PAPP-A and ADAM 12 too (P<0.01), while there was no relationship between maternal serum freeβ-hCG and PAPP-A, ADAM 12 (both P>0.01).
5. Conclusion
The maternal serum PAPP-A and ADAM 12 concentration were increased with the gestational age increased during the first trimester pregnancy in local Chinese population, while the maternal serum freeβ-hCG concentration was significantly decreased after 10 gestational weeks. There was relationship between ADAM 12 and PAPP-A, so the potency of combined screening with ADAM 12 and PAPP-A need further investigation. Our study could provide a theoretical basis for establishment of first trimester screening program in local Chinese pregnant women.
1.研究背景
在唐氏综合征(DS)中孕期血清学产前筛查方案中,三联(AFP+freeβ-hCG+uE3)产前筛查(简称三联筛查)比二联(AFP+freeβ-hCG)产前筛查(简称二联筛查)检出率高。但作为群体性预防措施,产前筛查在追求高检出率和低漏检率的同时,必须考察筛查方案的社会成本效益。与二联筛查相比,三联筛查方案增加了指标uE3的检测虽然可提高DS检出率,但也使筛查费用大幅增加。并且,同时值得注意的是：uE3在DS产前筛查风险率计算公式中的权重有限,增加uE3检测的三联筛查方案对风险率极低(小于1／1000)的二联筛查阴性病例和风险率高(大于或等于1／270)的二联筛查阳性病例的结果发挥影响的可能性较小。因而,有选择的进行三联筛查是一个值得探讨的问题。
为了在我国现行中孕期二联筛查的基础上进一步提高DS产前筛查检出率,同时又兼顾我国国情和筛查方案的社会成本效益,我们提出中孕期血清学“酌情三联产前筛查”(简称酌情三联筛查)方案,即以二联筛查为初筛方案,有选择的对部分二联筛查阴性病例进一步检测uE3行三联筛查,以期提高筛查检出率的同时降低医疗成本。
2.研究目的
1)分析中孕期唐氏综合征血清学二联筛查假阴性病例的筛查风险率区间,论证对部分二联筛查阴性病例(风险率在1／1000-1／270区间)加做uE3行三联筛查(酌情三联筛查)的意义；
2)比较酌情三联筛查和二联筛查的检出率和假阳性率,评估酌情三联筛查的效率；
3)比较酌情三联筛查和三联筛查的成本支出,评估酌情三联筛查的成本效益。
3.研究方法
收集孕15-20周中孕期二联筛查假阴性的孕妇资料共30例,其中有24例二联筛查风险率位于1／1000-1／270区间,定义为二联筛查假阴性组；随机抽取322例同时期中孕期二联筛查风险率位于1／1000-1／270区间的二联筛查真阴性的孕妇资料作为对照,定义为二联筛查真阴性组。用时间分辨荧光免疫分析技术测定两组间血清uE3水平并重新计算DS妊娠风险率,以1／270为切割值,判定三联筛查结果。结合文献报道的中国人群二联筛查和三联筛查的检出率和假阳性率,计算酌情三联筛查方案的检出率、假阳性率和经济支出情况,评价其相对于二联筛查和三联筛查方案的临床应用价值。
4.结果
本研究发现：80%的二联筛查假阴性病例其二联筛查风险率位于1／1000-1／270区间；经酌情三联筛查,6例二联筛查假阴性病例和3例二联筛查真阴性病例转变为筛查阳性。与二联筛查方案比较,酌情三联筛查方案可以在不增加假阳性率的基础上将DS妊娠的检出率提高10%。与三联筛查方案比较,酌情三联筛查方案可以减少84.3%以上的uE3检测相关的费用支出。
5.结论
对风险率为1／1000-1／270的二联筛查阴性孕妇再检测血清uE3水平以进一步评估DS妊娠风险率的酌情三联筛查方案,既能提高原二联筛查的检出率,又能较常规三联筛查节约成本,可能是适合我国国情的唐氏综合征血清学筛查策略,同时也值得其它发展中国家借鉴。
本部分研究通过对大样本的少见而且收集难度大的二联筛查假阴性病例的回顾性研究,首创“酌情三联筛查”的概念,有助于国家现行DS产前筛查策略的改进,研究结果已发表于《Prenatal Diagnosis》。
第二部分正常双胎妊娠与单胎妊娠中孕期孕妇血清freeβ-hCG和AFP水平的比较研究
1.研究背景
随着辅助生育技术的开展及孕妇年龄高龄化,近年来双胎妊娠发生率呈现升高趋势。由于我国人口基数大,双胎妊娠孕妇已是不容忽视的一个庞大的群体。并且,双胎妊娠中至少一胎为染色体异常的发生率较同年龄组单胎妊娠高,所以很有必要开展对双胎妊娠孕妇唐氏综合征(DS)的产前筛查。然而,双胎妊娠DS产前筛查至今是该领域的一个盲区。有报道认为,早孕期胎儿颈部透明带(NT)测定对双胎妊娠DS筛查的价值较大,但NT技术要求高、检测通量小且我国医疗资源有限,普及难度大。虽然血清学产前筛查方案在双胎妊娠中的应用价值一直备受争议,但原因之一可能是由于以单胎妊娠孕妇参数建立的双胎妊娠产前筛查方案欠合理。目前国外有关双胎妊娠孕妇联合freeβ-hCG和AFP的中孕期血清学二联筛查的资料很少,而国内更是缺乏大样本系统研究。通过建立双胎妊娠特异性的孕妇血清标志物参考值范围来完善我国双胎妊娠血清学二联筛查方案,有可能成为我国双胎妊娠DS产前筛查的一条出路。
2.研究目的
本研究旨在1)探讨双胎妊娠孕妇中孕期血清学二联筛查时孕妇血清freeβ-hCG和AFP变化规律；2)明确单胎妊娠与双胎妊娠孕妇血清free p-hCG和AFP水平是否存在差异和相关性。
3.方法
收集孕15～20周双胎妊娠孕妇456例为研究组,随机选择同时期单胎妊娠孕妇12,067例作为对照组；用时间分辨荧光免疫分析技术测定两组孕妇血清freeβ-hCG和AFP浓度,观察中孕期双胎妊娠和单胎妊娠孕妇上述血清标志物的变化特点,比较各孕周两组间freeβ-hCG和AFP水平的差异及相关性。
4.结果
所有病例经随访确定为非唐氏综合征妊娠。从孕15周到孕20周,单胎组孕妇血清freeβ-hCG水平逐渐降低,而双胎组孕妇血清freeβ-hCG水平呈波浪状下降；双胎妊娠组freeβ-hCG水平与单胎妊娠组的两倍值在孕16、17和19周有显著性差异(P均＜0.05)。从孕15周到20周,单胎组孕妇血清AFP水平逐渐升高,而双胎组孕妇血清AFP水平呈波浪状上升；双胎妊娠组AFP水平与单胎妊娠组的两倍值在孕16周和19周有显著性差异(P均＜0.05)。单胎组绝大多数孕周孕妇血清freeβ-hCG和AFP水平与体重相关；而双胎组绝大多数孕周孕妇血清freeβ-hCG和AFP水平与体重没有显著性相关。
5.结论
双胎妊娠孕妇血清freeβ-hCG和AFP水平与单胎妊娠数值间不存在固定的两倍关系,且与孕妇体重间不存在稳定的相关性,双胎妊娠孕妇血清二联筛查不宜参照单胎模式,而应以双胎妊娠孕妇血清freeβ-hCG和AFP水平及体重参考值建立其特异性DS产前筛查模式。
本部分研究在长期原始数据积累和大样本统计分析的基础上,提出根据双胎妊娠筛查指标参考值建立双胎血清学筛查模式并创建了部分双胎妊娠筛查指标数据资料,填补了国内空白。研究结果已发表于《Prenatal Diagnosis》。
第三部分中国人群早孕期孕妇血清freeβ-hCG、PAPP-A和ADAM 12水平变化
1.研究背景
唐氏综合征(DS)早孕期产前筛查在我国尚未大规模开展,但这无疑是今后DS产前筛查工作的发展趋势。国外报道,结合freeβ-hCG、PAPP-A和胎儿颈部透明带(NT)的早孕期联合筛查方案是最佳方案；但NT测定技术要求高、检测通量小,受限于医疗资源而不易临床普及。去整合素金属蛋白酶12(ADAM 12)是新近发现的一个高效的早孕期DS筛查血清标志物,有望替代NT提高早孕期DS产前筛查效率。探讨通量较大且不受超声检测能力所限的早孕期产前筛查方案有助于早孕期产前筛查的开展。目前少见早孕期freeβ-hCG和PAPP-A在大样本中国人群中的研究报道,更罕见ADAM 12的相关报告。
2.研究目的
探索中国孕妇早孕期血清freeβ-hCG、PAPP-A和ADAM 12水平的变化规律及相关性,为建立中国孕妇早孕期血清学DS产前筛查方案提供理论依据。
3.方法
收集2007年7月～2010年2月间在浙江大学医学院附属妇产科医院行早孕期(孕7-13周)检查的单胎妊娠孕妇资料685例,其中1例为DS妊娠；用时间分辨荧光免疫分析技术测定孕妇血清freeβ-hCG、PAPP-A和ADAM 12水平,统计分析各标志物与体重、孕周的关系及各标志物之间的相关性。
4.结果
从孕≦9周到孕13周,非DS妊娠孕妇血清PAPP-A浓度中位数分别为876.00、1365.00、2380.00、3995.00和5305.00 mU／L,ADAM 12浓度中位数分别为282.55、376.80、436.36、547.43和634.08 ng／ml,两者水平均随孕周的增加而增高；freeβ-hCG浓度中位数分别为87.30、86.45、70.40、59.45和42.10 ng／ml,其水平在孕9～10周基本稳定在一个平台,孕10周后迅速下降。各血清标志物与孕周和孕妇体重之间均存在相关性(P均＜0.01)。PAPP-A和ADAM 12之间存在相关性(P＜0.01),而freeβ-hCG与PAPP-A及ADAM 12均无相关性(P均＞0.01)。与非DS妊娠孕妇血清标志物浓度中位数比较,DS妊娠孕妇freeβ-hCG水平升高,PAPP-A和ADAM 12水平降低。
5.结论
我国人群早孕期孕妇血清PAPP-A和ADAM 12水平均随孕周的增加而增高,freeβ-hCG水平于孕10周后明显下降。早孕期孕妇血清ADAM 12与PAPP-A有相关性,两者联合应用的效价有待进一步探讨。
本部分研究验证了我国人群早孕期孕妇血清PAPP-A和freeβ-hCG变化趋势,提出AMAM 12可能不是一个独立的DS早孕期产前筛查指标,为我国早孕期产前筛查方案的探索和建立提供了理论依据。
Chapter One Contingent triple-screening for Down syndrome in the second trimester:a feasibility study in Mainland Chinese population
1. Background
The detection rate of second trimester maternal serum triple-screening (AFP+freeβ-hCG+uE3) program is higher than that of double-screening (AFP+freeβ-hCG). But the costs for triple-screening increased too due to one more detection index added in. In order to improve the detection rate of Down syndrome and reduce the costs just based on current routine double-screening program in China, and taking into account of the actual situation of Chinese economy& technology and the cost-effectiveness of program, we proposed a contingent triple-screening program, which performing triple-screening in pregnant women with DS risks between 1/270 and 1/1000 at routine double-screening.
2. Objectives
This study was designed for the following purposes:(1) to determine whether the DS risks between 1/270 and 1/1000 at routine double-screening is a feasible range of contingent triple-screening program; (2) to explore the efficacy of contingent triple-screening compared with routine double-screening in the second trimester; (3) to evaluate the economic value of the contingent triple-screening compared with routine triple-screening in the second trimester.
3. Methods
30 maternal serum samples of double-screening false-negative cases were collected and 24 of them had DS risks between 1/270 and 1/1000 at routine double-screening. Maternal serum concentrations of AFP, free P-hCG and uE3 were measured by time-resolved fluoroimmunoassay in 24 double-screening false-negative (DSFN) and 322 double-screening true-negative (DSTN) pregnancies with DS risks between 1/1000- 1/270 at routine double-screening performed at 15-20 weeks of gestation. DS risk of each pregnancy was calculated by computer software. The detection rate (DR), false positive rate (FPR), and costs of contingent triple-screening were calculated and compared to routine double-screening and triple-screening methods.
4. Results
80% double-screening false-negative cases had DS risks between 1/270 and 1/1000 at routine double-screening.6 of 24 DSFN and 3 of 322 DSTN were contingent triple-screening positive. Compared to routine double-screening, DR of contingent triple-screening increased by 10%(from 50% to 60%) without a significant increase of FPR (p>0.05). When compared to routine triple-screening, uE3 costs in contingent triple-screening were reduced by more than 84.3%.
5. Conclusions
Second trimester maternal serum contingent triple-screening could not only improve the efficacy of screening but also reduce the health care costs. It could be effective and suitable for prenatal care in Mainland China. Governments and Health Agencies of other developing countries may also find this strategy cost-effective.
This was the first introduction of the concept of "contingent triple-screening program" in the world. Our results has been published in'Prenatal Diagnosis'(Prenat Diagn.2010 Jan; 30(1):74-6.), a core journal in the field of prenatal care.
Chapter Two Second-trimester maternal serum free-β-human chorionic gonadotropin and a-fetoprotein levels in normal twin and singleton pregnancies
1. Background
Twin pregnancies are frequent in China and the incidence of having at least one Down Syndrome (DS)-affected fetus in twin pregnancies was higher than that of singleton pregnancies, thus it is important to carry out prenatal screening for twin pregnancies. However, the value of maternal serum screening in twin pregnancies is still controversial. In current prenatal screening for twin pregnancies, the estimated risk of DS in twin pregnancies was calculated based on the theory that maternal serum concentration of markers in twins would be twice of that in singletons. We may suggest that the current maternal serum screening programs, which are based on the data collected from singleton pregnancies seem to be unreasonable for DS screening in twin pregnancies. It is necessary to establish special gestational age-specific mid-trimester normal medians of maternal serum freeβ-hCG and AFP for DS screening in twin pregnancies.
2. Objectives
The study was designed to explore the changing trends of the levels of maternal serum freeβ-hCG and AFP used in second-trimester DS screening for twin pregnancies. And to confirm whether there are differences between Chinese normal twin and singleton pregnancies in the levels of maternal serum freeβ-hCG and AFP.
3. Methods
The concentrations of maternal serum markers of 456 twin pregnancies and 12,067 singleton controls in gestational 15 to 20 weeks were measured by time-resolved fluoroimmunoassay, and the levels of markers were compared between the twins and singletons in each gestational week.
4. Results
All cases had been followed-up till 1 month after childbirth and no childbirth with DS was found. Significant differences were found between the levels of freeβ-hCG in twins and twice of those in singletons in 16,17 and 19 gestational weeks (p< 0.05 for all). While considering AFP, significant differences were found in 16 and 19 gestational weeks (p< 0.05 for both). In singleton pregnancies there were significant correlations between the levels of makers and maternal weights in most gestational week, while no correlations were found in twins between the levels of markers and maternal weights in most gestational weeks.
5. Conclusions
The Chinese gestational age-specific levels of maternal serum markers in normal twins are not twice as those in singletons. The current weight-correction model for DS screening may be not feasible for twins. It is necessary to establish special gestational age specific mid-trimester normal medians of the freeβ-hCG and AFP and special weight-correction model for DS screening in twin pregnancies. Our study for medians of freeβ-hCG and AFP in Chinese twin pregnancies will help to establish specific second trimester DS screening model for Chinese twin-prenatal care and the results has been published in'Prenatal Diagnosis'(Prenat Diagn.2008 Aug; 28(8):735-8.), a core journal in the field of prenatal care.
Chapter Three Maternal serum freeβ-hCG, PAPP-A, and ADAM 12 levels in local Chinese population during the first trimester
1. Background
First trimester prenatal screening has not yet carried out widespread in China, but it is undoubtedly the tendency of the future clinical work with prenatal screening. So, it is necessary to gradually carry out basic research related to first trimester screening. Among all screening programs in first trimester, the combined screening (Freeβ-hCG+PAPP-A+NT) is the best. But NT measurement is so difficult and it couldn't be performed as a routine screening program in current China. A Disintegrin and Metalloproteinase 12 (ADAM 12) is a recently discovered new serum marker, which is considered increasing the detection rate of DS screening significantly. It is rarely reported about freeβ-hCG, PAPP-A and ADAM 12 in the Chinese population of large sample study of first trimester pregnancy.
2. Objectives
To explore maternal serum freeβ-hCG, PAPP-A and ADAM 12 levels in the first trimester in local Chinese population, in order to provide a theoretical basis for establishment of first trimester screening program in local Chinese pregnant women.
3. Methods
From July 2007 to February 2010,685 maternal serum samples(1 DS pregnancy and 684 non-DS pregnancies) were collected from women with singleton pregnancy who received first trimester (7-13 gestational weeks) examination in the Affiliated Women's Hospital, College of Medicine, Zhejiang University. Levels of freeβ-hCG, PAPP-A and ADAM 12 were measured by commercial time-resolved fluoroimmunoassay. Statistical analysis was performed using SPSS 16.0 software to evaluate the relationship between each serum marker and weight, gestational age, and the correlations between markers were analyzed too.
4. Results
After statistical analysis, there was no significant differences were found between the maternal ages and weights in each gestational week, and no correlations were found between the maternal weights and gestational weeks either (P>0.01 for all). From 9th gestational week to 13th gestational week, the median of maternal serum PAPP-A concentration in non-DS was 876.00,1365.00,2380.00,3995.00 and 5305.00 mU/L respectively. While the median of maternal serum ADAM 12 concentration in non-DS was 282.55,376.80,436.36,547.43 and 634.08 ng/ml respectively.The concentrations of both serum markers above were increased with the gestational weeks increased. The median of maternal serum freeβ-hCG concentration in non-DS was 87.30,86.45,70.40, 59.45 and 42.10 ng/ml respectively, and it was significantly decreased after 10 gestational weeks. Relationship could be found between each serum marker and gestational weeks, maternal weights (P<0.01 for all), and correlation could be found between PAPP-A and ADAM 12 too (P<0.01), while there was no relationship between maternal serum freeβ-hCG and PAPP-A, ADAM 12 (both P>0.01).
5. Conclusion
The maternal serum PAPP-A and ADAM 12 concentration were increased with the gestational age increased during the first trimester pregnancy in local Chinese population, while the maternal serum freeβ-hCG concentration was significantly decreased after 10 gestational weeks. There was relationship between ADAM 12 and PAPP-A, so the potency of combined screening with ADAM 12 and PAPP-A need further investigation. Our study could provide a theoretical basis for establishment of first trimester screening program in local Chinese pregnant women.
引文
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