Evaluation of multiple-marker screening for Down syndrome in a statewide population

Abstract

Our purpose was to evaluate our experience with a statewide, multiple-marker Down syndrome screening program. The results of 18,712 screening tests performed from July 1, 1991, to Oct. 31, 1992, were reviewed. Amniocentesis and aneuploidy detection rates were compared with the experience of a previous year (1989-1990) in which material serum alpha-fetoprotein was used for detection of Down syndrome. Positive screening tests (Down syndrome risk > or = 1/190) occurred in 665 of 18,712 (3.5%) patients; 516 of 665 (78%) patients accepted amniocentesis. Fifteen aneuploidies were identified: 12 trisomy 21, one trisomy 18, one trisomy 13, and one 48,XXXY. The overall detection rate was one in 34 amniocenteses performed; for trisomy 21 it was one in 43. In a previous year in which maternal serum alpha-fetoprotein alone was used, 3.6% had positive screening tests (Down syndrome risk > or = 270); the detection rate for all aneuploidies was one in 57 amniocenteses, and for trisomy 21 it was one in 114. The expanded maternal serum alpha-fetoprotein test was well accepted by clinicians, with 36% of gravid state residents undergoing screening. The multiple marker test is a good screening tool and is superior to material serum alpha-fetoprotein alone.