87: Noninvasive prenatal testing: 100,000 patients–clinical impact

As the first laboratory to offer massively parallel sequencing-based NIPT for aneuploidies we have been able to collect the largest clinical population experience data to date, including >100,000 clinical samples from all 50 states, including 13 international countries. The objective of this study is to give a robust clinical picture of the current laboratory performance of the MaterniT21 PLUS LDT. Data contained within this study were generated in our CLIA-licensed, CAP-accredited laboratory between August 2012 to June 2013 in patients with high-risk pregnancies. Samples were assessed for trisomies 13, 18, 21 and for the presence of chromosome Y-specific DNA. Samples received between February and June 2013 were also tested for allosome aneuploidies 46,X; 47,XXY; 47, XYY; and 47,XXX. NIPT patients most commonly undergo testing at an average of 15 weeks and 3 days gestation; are 35.1 years of age at the time of testing. The positivity rate for 47,+21 was 1.51%. This was followed by 0.45% and 0.21% rate for 47,+18 and 47,+13, respectively. NIPT positivity rates are similar to previous large clinical studies of aneuploidy rates in women of maternal age ≥ 35 undergoing amniocentesis. 11,300 samples were identified as high-risk by serum biochemical screening. Of these, the positivity rate by NIPT was only 2.3%, giving a 96.0% false positive rate for serum screening. Additionally, 3519 patients had multifetal gestations (3.5%); of these, only 92 had positive NIPT results, potentially reducing (in twins) the number of invasive procedures by 97.4% (7038 to 184). Although NIPT has only been commercially offered for 2+ years, the clinical impact for both patient and clinician has been dramatic. The risks associated with invasive testing have been reduced by providing another important assessment of aneuploidy status in the high risk population. The accuracy and positivity rate are as predicted by clinical validations and the test demonstrates improvement over the current standards of care.Tabled 1Positive results for patients maternal age ≥ 35 years Open table in a new tab