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

OBJECTIVE: Our purpose was to evaluate our experience with a statewide, multiple-marker Down syndrome screening program. STUDY DESIGN: 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 α-fetoprotein was used for detection of Down syndrome. RESULTS: Positive screening tests (Down syndrome risk>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 α-fetoprotein alone was used, 3.6% had positive screening tests (Down syndrome risk ≥ 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 α-fetoprotein test was well accepted by clinicians, with 36% of gravid state residents undergoing screening. CONCLUSION: The multiple marker test is a good screening tool and is superior to material serum α-fetoprotein alone.