HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Erratum (v107,p955) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Palomaki, G. E. Articles by Haddow, J. E. Search for Related Content PubMed PubMed Citation Articles by Palomaki, G. E. Articles by Haddow, J. E. Related Collections Epidemiology/public health Genetics and teratology Prenatal Diagnosis

Comparing Three Screening Strategies for Combining First- and Second-Trimester Down Syndrome Markers

From the ¹Division of Medical Screening, Department of Pathology and Laboratory Medicine, Women & Infants Hospital, Providence, Rhode Island; and ²Electric Dreams, Scarborough, Maine.

OBJECTIVE: To describe the choices and tradeoffs inherent in 3 published strategies that combine first- and second-trimester markers for Down syndrome screening.

METHODS: Published marker distributions for Down syndrome and unaffected pregnancies in the first and second trimesters were combined with a maternal age distribution and age-associated Down syndrome risk in a statistical model to compare sequential, contingent, and integrated screening.

RESULTS: Sequential and contingent screening strategies are always less efficient (higher false-positive rate for a given detection rate) than integrated screening, but the reduction in efficiency is dependent on the combination of risk cutoffs chosen. At a fixed false-positive rate, sequential and contingent strategies perform better when a higher proportion of the false positives occur in the second trimester. For all 3 strategies, increasing the overall false-positive rate from 2% to 5% increases detection (from approximately 85% to 91%). Although associated with reduced screening efficiency compared with integrated screening, both sequential and contingent screening identify the majority of detected Down syndrome cases early. With contingent screening, the process is also completed in the first trimester for most women.

CONCLUSION: Integrated screening is the most efficient of the 3 strategies, but it is possible to select risk cutoffs for both sequential and contingent strategies that minimize losses in efficiency while maintaining early detection and early completion. For all of these strategies, well-designed intervention trials are needed to determine acceptability to women and providers in primary care settings and to assess real-world performance.

LEVEL OF EVIDENCE: III

This article has been cited by other articles:

				E. H. Philipson, M. Callahan, and J. E. Jelovsek First-Trimester and Second-Trimester Screening at a Community Hospital: Experience From the First Year of Implementation Obstet. Gynecol., August 1, 2008; 112(2): 218 - 222. [Abstract] [Full Text] [PDF]

				B. Skotko Comparing three screening strategies for combining first- and second-trimester down syndrome markers. Obstet. Gynecol., May 1, 2006; 107(5): 1170 - 1170. [Full Text] [PDF]

				J. P Neilson and Z. Alfirevic Optimising prenatal diagnosis of Down's syndrome. BMJ, February 25, 2006; 332(7539): 433 - 434. [Full Text] [PDF]