The Evaluation of Integrated Test as an Antenatal Screening Test for Down's Syndrome in Korea

ABSTRACT

BACKGROUND: Antenatal screening for Down's syndrome has been developed and improved over the past 20 yr. Recently, integrated test, which combines the first and second trimester markers has shown the highest detection rate (DR) and lowest false positive rate (FPR) among Down's syndrome screening tests currently in use. The purposes of this study were to evaluate the screening performance of integrated test and to compare the results with triple test studies in Korea. METHODS: The study population consisted of Korean pregnant women who underwent triple or integrated test between April 2005 and December 2008. Triple test was performed using measurements of alpha-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG) in the second trimester. Integrated test was performed using nuchal translucency (NT) by ultrasonography and pregnancy-associated plasma protein A (PAPP-A) from maternal serum in the first trimester, and AFP, uE3, hCG, and inhibin-A in the second trimester. The screening performance of each test was evaluated by DR and FPR. RESULTS: Twenty-seven Down's syndrome pregnancies were confirmed in women screened by triple (N=6,736) or integrated test (N=7,688). At 1100, 1270, and 1300 of risk cutoff, triple test showed 45%, 73%, and 73% of DR and 4.7%, 11.2%, and 12.4% of FPR, respectively. At 1100, 1150, and 1300 of risk cutoff, integrated test showed 63%, 69%, and 75% of DR and 1.5%, 1.9%, and 3.0% of FPR, respectively. CONCLUSIONS: Integrated test showed higher DR and lower FPR, demonstrating better screening performance than triple test.