Correspondence

Triple-Marker Screening of Serum for Down's Syndrome

N Engl J Med 1994; 331:681-682September 8, 1994

Article

To the Editor:

Haddow et al. (April 21 issue)1 report that among pregnant women 35 years of age or older, screening serum for three substances (alpha-fetoprotein, human chorionic gonadotropin, and estriol) can identify 89 percent of fetuses with Down's syndrome, with a false positive rate of 25 percent. We must distinguish how these results relate to individual women (i.e., the effect on patient care) from their effect in larger populations (i.e., the implications for public policy). The authors seem to suggest that preference should be given to the latter.

The practicing physician is concerned with individual pregnant women. The challenge is to translate a potential risk (such as that for Down's syndrome) into an action plan that is realistic, reasonable, and helpful to the woman. Of 636 consecutive women referred to me after maternal serum alpha-fetoprotein or triple-marker screening revealed an increased risk for Down's syndrome, 292 (46 percent) did and 344 (54 percent) did not choose to have amniocentesis after the genetic history of the family was found to be noncontributory and detailed ultrasonography had shown a normal fetus.

The decision to have or not to have an amniocentesis was made by the individual woman or couple and was based on various reasons, but never on the potential cost savings to society. Other women, referred because of advanced maternal age, frequently chose to have ultrasonography, with or without triple-marker screening of serum, rather than amniocentesis. They knew these tests could not rule out Down's syndrome with certainty, but they were comfortable with the remaining risk.

These results indicate that women are willing and able to decide for themselves about amniocentesis and to accept a certain residual risk of Down's syndrome. Is the public, or are policy makers, able to exercise similar responsibilities? One important difference between patient care and public policy is that implementing public policy places the burden of the risk on others, not on the persons making the decision. At this point it seems premature to suggest a single protocol based on triple-marker testing of serum.

Jurgen Herrmann, M.D.
Great Lakes Genetics, Milwaukee, WI 53226

1 References

1. 1

   Haddow JE, Palomaki GE, Knight GJ, Cunningham GC, Lustig LS, Boyd PA. Reducing the need for amniocentesis in women 35 years of age or older with serum markers for screening. N Engl J Med 1994;330:1114-1118
   Full Text | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: Our study of pregnant women 35 years of age or older was designed to provide data to aid both in the development of public policy and in the care of individual women. The women provided with referral care by Dr. Herrmann exemplify how the application of the existing prenatal-screening policy complements individual patient care. All the women referred to his care were first identified as being at high risk for Down's syndrome on the basis of maternal serum alpha-fetoprotein or triple-marker levels (public policy). The same body of information that shaped policy for the screening cutoffs was also available for use in counseling individual patients (patient care). The data from our study simply extend that body of information and allow additional public policy options to be considered.

James E. Haddow, M.D.
Glenn E. Palomaki, B.S.
Foundation for Blood Research, Scarborough, ME 04074