Kaiser harmony test1/21/2024 Patient age at delivery, gestational age at screening, indication for screening, and maternal serum screen results were extracted from outpatient clinic notes. Medical records were retrospectively reviewed for 632 consecutive patients who had NIPS and were seen between March 2012 and December 2013 in the Prenatal Genetics and Fetal Therapy (PGFT) Program, a tertiary referral center for prenatal genetic counseling and prenatal diagnosis located at UWMC. The requirement to obtain written consent and the requirement for Health Insurance Portability and Accountability Act (HIPAA) authorization were both waived by the IRB. 47,683) and the Institutional Review Board (IRB) at the University of Washington Medical Center (UWMC). This study was approved by the Human Subjects Division (Application no. Benefits and limitations of using NIPS in clinical practice and recommendations for follow-up of abnormal results are discussed. Some discordant or unusual cases are described in detail. Underlying biological causes for discordant results were determined where possible. Performance was evaluated by calculating standard metrics such as PPV. Here we present our first two years’ experience with NIPS in a tertiary referral center. Although some publications sponsored by commercial laboratories performing NIPS have included PPV and NPV, there is minimal independent data available on the performance of NIPS in actual clinical practice. Īlthough sensitivity and specificity are important performance metrics, positive predictive value (PPV) and negative predictive value (NPV) become more clinically relevant after results have returned. Somewhat lower sensitivities and specificities are seen when screening for trisomy 18 (T18), trisomy 13 (T13), and the sex chromosome aneuploidies (SCAs: 45,X 47,XXX 47,XXY 47,XYY). Very high sensitivity (98.6 - 100 %) and specificity (99.7 - 100 %) have been reported in multiple clinical validation studies of NIPS for Down syndrome (DS). Non-invasive prenatal screening (NIPS) for fetal chromosome abnormalities is based on either massively parallel sequencing or analysis of single nucleotide polymorphism (SNP) patterns from cfDNA in maternal serum. After 10 weeks gestation, an average of 10 % of maternal cfDNA is placental in origin. During pregnancy, placental cytotrophoblastic cells are shed into maternal circulation and contribute to the cfDNA pool in the maternal bloodstream. The fragments are most frequently 150-180 base pairs in length and derive mostly from apoptotic cells. Gestational age at time of screening was not associated with concordance of screen results ( P = 0.722).Ĭell-free deoxyribonucleic acid (cfDNA) refers to fragments of DNA circulating freely in the plasma. Maternal age at delivery was significantly lower for patients with abnormal discordant results, compared to patients with abnormal concordant results ( P = 0.034). This incomplete follow-up of normal NIPS results does not affect PPV calculations, but it did preclude calculations of sensitivity, specificity, and NPV. Of 578 patients with normal NIPS results, normal pregnancy outcome was confirmed for 156 (27 %) patients. The PPV for all conditions included in the screen was 77.4 % (95 % CI, 63.4 – 87.3). Forty-one of 55 abnormal NIPS results were concordant with abnormal fetal outcomes, 12 were discordant, and 2 were undetermined. However, all four laboratories are represented in both the normal and abnormal results groups. Of 632 patients undergoing NIPS, 92 % of tests were performed in one of the four major commercial laboratories offering testing.
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