Differentiation Of Down’s Serology Screening And NIPT In Pregnant Women Of Different Ages

Objective : To explore the screening efficiency and economic benefits of Tang’s serological screening and NIPT in pregnant women of different ages,and to provide reference for clinical selection of appropriate screening program.Method : Single pregnant women who underwent Down’s serological screening and NIPT in the Outpatient Department of the First Affiliated Hospital of Shenzhen University from January 2017 to December 2019 were selected as the study subjects.The study subjects for serological screening were divided into group A1(less than 35 years old group),group B1(35-40 years old group)and group C1(greater than or equal to 40 years old group)according to the age of pregnant women.The study subjects for NIPT were divided into group A2(less than 35 years old group),group B2(35-40 years old group)and group C2(greater than or equal to 40 years old group).Retrospective analysis was used to collect the results of serological screening,NIPT detection,fetal chromosome results(those who underwent interventional prenatal diagnosis)and follow-up at birth,half an year and one year of age.The screening efficiency,economic benefits and safety effects of the two prenatal screening regimens among the three groups of pregnant women were analyzed,and whether the differences were statistically significant was compared,and the distribution characteristics of serological screening risk values of pregnant women finally diagnosed with chromosomal abnormalities were analyzed.Results:(1)A total of 10,466 Tang’s serological screening were performed in this paper,including 8916 in group A1,8707 in follow-up,and 97.66% in follow-up;1334in group B1 and 1240 in follow-up,with a follow-up rate of 92.95%;and 216 in group C1,179 in follow-up,with a follow-up rate of 82.87%.There were 9208 NIPT tests,including 7381 in group A2 and 7375 in follow-up,with a follow-up rate of 99.92%;1562 in group B2 and 1558 in follow-up,with a follow-up rate of 99.74%;and 265 in group C2 and 264 in follow-up,with a follow-up rate of 99.62%.(2)The high-risk rates of prenatal screening in different age groups were 10.52% in group A1,0.51% in group A2,38.76% in group B1,1.02% in group B2,87.04% in group C1,and 3.40% in group C2 in Tang’s serological screening and NIPT,respectively.The high risk rate of pregnant women screened by Tang’s serology increased with increasing age,and there were significant differences in pairwise comparisons among the three groups(P < 0.0167).The high risk rate of pregnant women in NIPT slightly increased with increasing age,the high risk rate of group C2 was higher than that of groups A2 and B2,the difference was statistically significant(P <0.0167),the high risk rate of group A2 B2 was not significantly different(P > 0.0167),and the high risk rate of NIPT was lower than that of Tang’s serological screening,the difference was statistically significant(P < 0.05).(3)The positive predictive values of prenatal screening in different age groups were A1 2.33%,A2 96.88%,B1 1.89%,B2 100%,C1 1.99%,and C2 100% in Tang’s serological screening and NIPT,respectively,and the positive predictive value of NIPT was significantly higher than that of Tang’s serological screening,and the difference was statistically significant(P < 0.05).(4)The diagnostic coincidence rates of prenatal screening in different age groups were89.67% in group A1 and 99.90% in group A2,61.84% in group B1 and 99.67% in group B2,14.35% in group C1 and 99.62% in group C2 in Tang’s serological screening and NIPT,respectively.The diagnostic coincidence rate of Tang’s serological screening decreased with the increase of maternal age,and there were significant differences in pairwise comparisons among the three groups(P < 0.0167).There was no significant correlation between the diagnostic coincidence rate in NIPT and the age of pregnant women at the expected date of delivery,and there were no significant differences in pairwise comparisons among the three groups(P < 0.0167);the diagnostic coincidence rate of NIPT was significantly higher than that of serological screening,and the difference was statistically significant(P < 0.05).(5)At the current price in this study area,the cost-effectiveness ratios of serological screening and NIPT screening in different age groups were: 40,5910 yuan in group A1,22,6397 yuan in group A2,35,3728 yuan in group B1,12,7736 yuan in group B2,30,9656 yuan in group C1,and 35,826 yuan in group C2,respectively.The cost-effectiveness ratio of NIPT was lower than that of serological screening in all age groups,and gradually decreased with increasing age.(6)The positive predictive values of NIPT for other autosomes and sex chromosomes were 35% and 56.5%,respectively,which were significantly lower than those for trisomy 21,18,and 13,and the difference was statistically significant(P <0.05).Twenty-eight patients were diagnosed with trisomy 21,18,and 13 at high risk by Tang’s serological screening,of which 25(89.29%)had a risk value ≥ 1:100 by serological screening;the total number of children diagnosed with chromosomal abnormalities(including trisomy 21,18,and 13,other chromosomal abnormalities,and other pathogenic CMA results abnormalities)was 50,of which 41(82%)had a risk value ≥ 1:100 by serological screening for pregnant women.Conclusion:(1)The results of Tang’s serological screening are greatly affected by the age of pregnant women,and the screening efficacy decreases with the increase of maternal age,which is not applicable to elderly pregnant women.(2)NIPT are not affected by maternal age,screening efficacy is high,and screening for trisomy 21,18,and 13 is significantly superior to serological screening and can be recommended as first-line screening.(3)NIPT is of limited value for the screening of chromosomal abnormalities outside trisomy 21,18,and 13 and is not recommended as a routine screening.(4)According to the current price in this study area,NIPT has the best cost-effectiveness ratio and can be recommended as the first-line screening program in all age groups;and the economic effect of NIPT screening in elderly pregnant women is better than that in the non-elderly group.(5)pregnant women with serological screening risk values greater than 1:100 need to be paid attention to regardless of whether NIPT is low risk.