title: Applicability of first-trimester combined screening for fetal trisomy 21 in a resource-limited setting in mainland China.
abstract: OBJECTIVE
  To assess the feasibility and performance of the first-trimester combined screening test for trisomy 21 in a resource-limited setting in mainland China.
  
  
  METHODS
  Prospective observational cohort study.
  
  
  METHODS
  First Affiliated Hospital of Kunming Medical University, China.
  
  
  METHODS
  Ten thousand four hundred and forty-two pregnant women requesting first-trimester screening.
  
  
  METHODS
  The combined screening test was performed from May 2012 to December 2014. Women with a high-risk result (≥1:600) were offered further confirmatory tests after counselling. The threshold for high risk was determined by Monte Carlo simulation to achieve a 5% false-positive rate according to the local age distribution. Pregnancy outcome and screening results were recorded for all women and monthly audits were conducted.
  
  
  METHODS
  Sensitivity, screen positive rate, cost per case of Down syndrome detected.
  
  
  RESULTS
  Six hundred and ten women (5.8% of the total screened) had a high-risk screening test, of whom 274 (44.9%) underwent a diagnostic test and 169 (27.7%) opted for a noninvasive prenatal screening test (NIPT); 160 (26.2%) declined further testing after counselling. The pregnancy outcome was available for 10 174 (97.4%) of the women. The observed incidence of Down syndrome was 0.13% (1/750). All 14 women with a trisomy 21 pregnancy had a high-risk screening test result. The cost per Down syndrome detected was RMB596 686 compared with RMB1.79 million if all had been screened by NIPT.
  
  
  CONCLUSIONS
  The combined screening test appears to be a more cost-effective strategy in mainland China. Screening performance in China would be improved by adopting Chinese-specific models, external quality control and assurance, and establishing risk thresholds appropriate for the age distribution of the population.
  
  
  CONCLUSIONS
  Combined first-trimester Downs screening in China was improved by adopting Chinese-specific models and external QC.
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: B
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR, China.
authors.forename: D S
authors.initials: DS
authors.lastname: Sahota
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR, China.
authors.forename: T T
authors.initials: TT
authors.lastname: Lao
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: S Q
authors.initials: SQ
authors.lastname: Hu
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: Q Y
authors.initials: QY
authors.lastname: Liu
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
authors.forename: D
authors.initials: D
authors.lastname: Tang
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China. marunmeikmmc@163.com.
authors.forename: R M
authors.initials: RM
authors.lastname: Ma
mesh_terms: D000328:Adult; D002681:China; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000032:analysis; D004314:Down Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D005240:Feasibility Studies; D005260:Female; D006295:Health Resources / Q000191:economics; D006801:Humans; D008423:Maternal Age; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011296:Prenatal Diagnosis / Q000191:economics / Q000379:methods; D011446:Prospective Studies; D012307:Risk Factors; D014463:Ultrasonography / Q000191:economics
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A
keywords: China; Down syndrome; cost-effectiveness; first-trimester screening; noninvasive prenatal testing; nuchal translucency; 中国; 唐氏综合征; 成本效益; 早孕期联合筛查; 非侵入性产前检测; 颈项透明层