Special Column for Non-invasive Prenatal Testing
Clinical evaluation of true and false positive Z values among high-risk cases screened by non-invasive prenatal testing
Mo Jun, Ren Junqing, Yang Liqian, Shen Xuan, Zhao Danke, Xiao Yanbing
Published 2022-11-10
Cite as Chin J Med Genet, 2022, 39(11): 1187-1191. DOI: 10.3760/cma.j.cn511374-20220120-00046
Abstract
ObjectiveTo analyze the Z values of true and false positive cases by non-invasive prenatal testing (NIPT) in order to improve its accuracy in clinical practice.
MethodsResults of 24 384 NIPT tests were reviewed. For cases with high risks for trisomies 21, 18 and 13, the range of Z values in true and false positive cases was analyzed and discussed.
ResultsA total of 335 high-risk cases were identified by NIPT, among which 256 had elected prenatal diagnosis, 153 (59.77%) were verified as true positives, and 103 (40.23%) were false positives, and the area under the curve (AUC) was 0.9994. For NIPT screening, the positive predictive value (PPV) for trisomy 21 was 100% when Z > 13, regardless if the pregnant woman was over 35. When 3 < Z < 13, the PPV for trisomy 21 was 80% (8/10) for those > 35 and about 41.6% (5/12) for those < 35. For trisomy 18, the PPV was 100% when Z > 13, and only 14.3% (1/7) when 3 < Z < 13. NIPT showed that the positive predictive value of trisomy 13 was only 6.67% (1/15) when the trisomy 13 Z value was more than 20, the positive predictive value was 100% , and the trisomy 13 Z value was 3 < Z < 20.
ConclusionNIPT is a technique similar to prenatal diagnosis and has a high positive predictive value for trisomies 18 and 21. Proper classification and division of the high-risk Z value of NIPT can further improve the positive predictive values for trisomies 21, 18 and 13 in different intervals, and is more helpful to guide clinicians in genetic counseling for high-risk pregnant women. Meanwhile, the compliance of prenatal diagnosis in high risk NIPT pregnant women with Z value between 3~13 was improved.
Key words:
Non-invasive prenatal testing; Positive predictive value; True and false positive; Z value; Clinical evaluation
Contributor Information
Mo Jun
Department of Medical Genetics and Prenatal Diagnosis, Zunyi Maternal and Child Health Care Hospital, Zunyi, Guizhou 563000, China
Ren Junqing
Department of Medical Genetics and Prenatal Diagnosis, Zunyi Maternal and Child Health Care Hospital, Zunyi, Guizhou 563000, China
Yang Liqian
Department of Medical Genetics and Prenatal Diagnosis, Zunyi Maternal and Child Health Care Hospital, Zunyi, Guizhou 563000, China
Shen Xuan
Department of Medical Genetics and Prenatal Diagnosis, Zunyi Maternal and Child Health Care Hospital, Zunyi, Guizhou 563000, China
Zhao Danke
Department of Medical Genetics and Prenatal Diagnosis, Zunyi Maternal and Child Health Care Hospital, Zunyi, Guizhou 563000, China
Xiao Yanbing
Department of Medical Genetics and Prenatal Diagnosis, Zunyi Maternal and Child Health Care Hospital, Zunyi, Guizhou 563000, China
