547: A cost-effectiveness analysis of using non-invasive prenatal testing as a screening tool for Down syndrome

prenatal testing as a screening tool for Down syndrome Mika Ohno, Allison Allen, Yvonne Cheng, Brian Shaffer, Yair Blumenfeld, Mary Norton, Aaron Caughey Stanford University, Obstetrics and Gynecology, Stanford, CA, Oregon Health and Science University, Obstetrics and Gynecology, Portland, OR, UCSF, Obstetrics, Gynecology, and Reproductive Sciences, San Francisco, CA OBJECTIVE: Non-invasive prenatal testing (NIPT) has emerged as a promising technique to screen for Down syndrome (DS) with improved sensitivity and specificity compared to current screening. We investigated the cost-effectiveness of NIPT and contingent sequential screening (CSS) to screen for DS. STUDY DESIGN: A decision-analytic model compared CSS alone vs. NIPT alone vs. CSS followed by NIPT for screen-positive results. All costs and benefits were derived from the literature. Utilities were applied to life expectancies at a discount rate of 3% to generate QALYs. Baseline values were: for NIPT, a sensitivity of 99%, a specificity of 99%, and a cost of $235; for the contingent sequential screen, a sensitivity of 93%, a specificity of 95.8%, and a cost of $304. Baseline assumptions included a first-trimester prevalence of DS of 1:500, a 100% amniocentesis rate for screen positive results, and a 100% therapeutic abortion rate for positive amniocentesis results. A baseline 4.6% “no result” arm was included to account for inconclusive NIPT results. The cost-effectiveness threshold was set to $100,000 per QALY. Base-case and one-way sensitivity analyses were performed. RESULTS: At the baseline, using only a NIPT for screening is the most cost-effective strategy (for 1 million pregnant women NIPT alone costs $318M, QALY 30,008,389; CSS followed by NIPT costs $462M, QALY 30,007,941; CSS alone costs $491M, QALY 30,005,680). If the cost of the NIPT is greater than $432 or if the specificity of NIPT is below 96.8% then it is more cost-effective to perform CSS followed by NIPT. Above a specificity of 96.8% using only a NIPT is more costeffective. Finally, if the sensitivity of the NIPT is below 81.2% it is more cost-effective to perform CSS alone; above a sensitivity of 81.2%, using only a NIPT is more cost-effective. CONCLUSION: NIPT is a cost-effective means of screening for DS if it costs less than $432, has a specificity above 96.8%, and a sensitivity above 81.2%. 548 Antenatal testing in uncomplicated pregnancies: to initiate after 40 0/7 weeks or 41 0/7 weeks? Dhanya Mackeen, Paula Edelson, Susan Wisch, Lauren Plante, Stuart Weiner University of Pennsylvania, Department of Obstetrics and Gynecology, Philadelphia, PA, Thomas Jefferson University, Department of Obstetrics and Gynecology, Philadelphia, PA, Drexel University College of Medicine, Department of Obstetrics and Gynecology, Philadelphia, PA OBJECTIVE: To compare the outcomes of antenatal testing in women who received testing between 40 0/7 to 40 6/7 weeks versus those who received testing at 41 0/7 weeks. STUDY DESIGN: This is a retrospective study of women who had outpatient antenatal testing performed at Thomas Jefferson University between 5/6/02 and 11/17/11. We included women with singleton gestations without maternalmedicalorgestationalco-morbiditieswhowerereferredfortestingforthe sole indicationofgestationalage400/7weeks,whowerewell-dated.Women withmultiplegestation,medicalorfetal indicationsfortestingwereexcluded. We compared women who received antenatal testing between 400/7 and 40 6/7 weeks (Group 1) versus those who were tested at 41 0/7 weeks (Group 2). Women who received testing at both 40 and 41 weeks were counted only in the 40 week group. The primary outcome was abnormal testing requiring disposition to Labor & Delivery (L&D). We evaluated the reason sent, the disposition after evaluation in L&D and neonatal outcomes. RESULTS: There were 1251 pregnancies available for review: 827 in Group 1, 424 in Group 2. 215 (17%) were sent to L&D for further evaluation: 139 from Group 1, 76 from Group 2. Of those sent, 158 (73%) were admitted. There were no significant differences between groups with respect to being sent to L&D, the reason for which women were sent, admission to L&D, induction of labor, mode of delivery, admission to the neonatal ICU or neonatal length of stay. CONCLUSION: Pregnanciestestedat400/7weekswereidentifiedasabnormal and sent to L&D at the same rate as those at 41 0/7, with no increased rate failed induction of labor, Cesarean section or suboptimal neonatal outcome. By waiting until 41 0/7 to initiate surveillance, we are missing a number of pregnancies who may benefit from further evaluation and intervention, in our study 137/827 (16%) of otherwise uncomplicated pregnancies. Therefore, it is reasonable to initiate NST surveillance at EDD. Below a NIPT cost of $432, using a NIPT alone for screening is cost-effective. Above a NIPT cost of $432 it is more cost-effective to use CSS followed by a NIPT. Outcomes of using a NIPT as a screening tool for Down syndrome