ETHNICITY SARAH LITTLE, WILLIAM GROBMAN, ANTHONY ODIBO, DAVID STAMILIO, STEPHEN THUNG, AARON CAUGHEY, Brigham and Women’s Hospital, Boston, Massachusetts, Northwestern University, Chicago, Illinois, Washington University in St. Louis, St. Louis, Missouri, Yale University, New Haven, Connecticut, University of California, San Francisco, San Francisco, California OBJECTIVE: To evaluate the cost-effectiveness of antenatal screening for cystic fibrosis carrier status by ethnic group. STUDY DESIGN: A design analytic model was created in Data TreeAge Pro. Cystic fibrosis carrier screening vs. no screening was compared for 5 different ethnic groups: white non-Jewish, Ashkenazi Jew, black, Hispanic and Asian. We allowed for both similar and dissimilar ethnic backgrounds amongst couples. Primary outcome was cost per quality-adjusted life year (QALY) from a societal perspective. Baseline assumptions included a prevalence of carrier frequency of 4.1%, 3.9%, 1.7%, 1.6%, and 1.1% amongst Jewish, white, Hispanic, black and Asian populations, respectively and a test sensitivity of 92.1%, 86.5%, 70.4%, 63.1%, and 47.9%, respectively. We estimated the utility of having a child with cystic fibrosis at 0.9 and a SAB or therapeutic abortion (TAB) at 0.76 for two years. As a baseline, we assumed a 100% rate of amniocentesis if both partners screen positive and that all couples would pursue a TAB if a fetus had CF. Univariate and multivariate sensitivity analysis was performed. RESULTS: For white and Jewish couples, carrier screening was the dominant (less expensive, more effective) option. This result was sensitive to the probability of choosing amniocentesis and TAB. Screening was only cost-effective for those couples at least 50% likely to abort an affected fetus. For black, Hispanic and Asian couples cystic fibrosis carrier screening was not cost-effective at 2.6, 1.8 and 10.5 million dollars per QALY, respectively. Even if the test sensitivity for black, Hispanic or Asian ethnicity reached 100%, screening would still not be cost-effective for these groups given their low prevalence of disease. CONCLUSION: Screening for cystic fibrosis carrier status is only cost-effective for white and Jewish couples, and only for those couples likely to abort an affected fetus.