title: Effect of ethnicity on first trimester biomarkers for combined trisomy 21 screening: results from a multicenter study in six Asian countries.
abstract: OBJECTIVE
  To assess differences between first trimester trisomy 21 screening markers free beta chain of the human chorionic gonadotrophin (βhCG) and pregnancy-associated plasma protein A (PAPP-A) in pregnant women of six different Asian countries (China, Indonesia, Korea, Taiwan, Thailand, and Vietnam) and compare serum levels with those in women of European countries.
  
  
  METHODS
  Median and multiple of median (MoM) values of free βhCG and PAPP-A were determined in more than 3000 pregnant women from the Asian countries during their first trimester of pregnancy. Differences in MoM values between a European reference group from a previous multicenter evaluation and the Asian population were evaluated. Two different types of population correction factors for T21 risk estimation were assessed.
  
  
  RESULTS
  An at least 10% difference of median MoMs between European and Asian PAPP-A values was found to be statistically significant (p < 0.0001). The specificity of the screening did not show a big difference in individual countries, when using the country-specific correction factor compared with the overall Asian correction factor (<1.4%).
  
  
  CONCLUSIONS
  The use of a correction factor is recommended based on the differences in European and Asian MoM values. Developing country-specific medians in larger study populations can help identify clinical relevant differences and give the opportunity to explore a more accurate risk calculation.
authors: Department of Obstetrics and Gynaecology, Faculty of Medicine, Chulalongkorn University, Patumwan, Bangkok, Thailand.
authors: Saknan
authors: S
authors: Manotaya
authors: Roche Diagnostics, Clinical Operations Professional Diagnostics, Penzberg, Germany.
authors: Juergen
authors: J
authors: Zitzler
authors: Obstetrics and Gynaecology Hospital of Fudan University, Shanghai, China.
authors: Xiaotian
authors: X
authors: Li
authors: Department of Obstetrics and Gynaecology, Division Fetomaternal, FKUI/RSCM, Jakarta, Indonesia.
authors: Noroyono
authors: N
authors: Wibowo
authors: Department of Obstetrics and Gynaecology, Medical University Hospital, Ho Chi Minh City, Vietnam.
authors: Thi Mai
authors: TM
authors: Pham
authors: Department of Laboratory Medicine, CHA Bundang Medical Center, CHA University, Bundang-gu, Seongnam-si, Korea.
authors: Myung Seo
authors: MS
authors: Kang
authors: Department of Obstetrics, National Taiwan University Hospital, Taipei, Taiwan.
authors: Chien-Nan
authors: CN
authors: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D001208:Asia; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis* / Q000208:ethnology; D005060:Europe; D005260:Female; D005865:Gestational Age; D006801:Humans; D062145:Maternal Serum Screening Tests; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood* / Q000208:ethnology; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism*; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D044465:White People; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A