Combined first trimester screening for trisomy 21: Assessment of excess risk in case of free ß-human chorionic gonadotrophin between 5 and 10 multiples of the median.

OBJECTIVE: The first trimester combined risk of trisomy 21 is obtained by multiplying the risk related to maternal age by the likelihood ratios of nuchal translucency, free beta-human chorionic gonadotrophin (ß-hCG) and placenta associated plasma protein-A. Beyond five multiples of the median (MoM) of ß-hCG, the risk of trisomy 21 is truncated. The objective of the present study was to evaluate the evolution of the first trimester combined risk of trisomy 21 in individuals with first-trimester free-ß-hCG levels between 5 and 10 MoM. METHODS: We conducted a non-interventional cohort study from a 6-year database of combined first-trimester trisomy 21 screening of all individuals who underwent the screening in a French specialized medical analysis center. We included all pregnant individuals who had a serum-free ß-hCG between 5 and 10 MoM. Patients for whom the status of the fetus, with or without trisomy 21, was not identified by the outcome of the pregnancy or by a karyotype result were excluded from the study. The discriminatory capacity of free-ß-hCG above 5 MoM was studied by a receiver operating characteristic curve. We used an orthogonal polynomial regression to represent the evolution of likelihood ratios according to free-ß-hCG in MoM. RESULTS: Among 413 216 combined first-trimester screens of trisomy 21, 2239 (0.5%) screens met the inclusion criteria. In the selected population, 801 (35.8%) were excluded from the study because of missing fetal or neonatal status, and 46 (3.2%) fetuses out of 1438 included were diagnosed with trisomy 21. For free ß-hCG values between 5 and 10 MoM, the area under the curve is 0.56 (0.46-0.65). The scatterplot of the likelihood ratio of ß-hCG showed an increasing parabolic pattern: the likelihood of trisomy 21 increases with the free-ß-hCG threshold. CONCLUSION: To override the truncated risk of trisomy 21 in case of free ß-hCG values between 5 and 10 MoM, the study has allowed us to estimate the adjusted risk of trisomy 21, enabling health professionals to offer appropriate prenatal counseling.

Cost-effectiveness threshold of first-trimester Down syndrome maternal serum screening for the use of cell-free DNA as a second-tier screening test.

INTRODUCTION: We aimed to identify the most relevant cost-effectiveness threshold of first-trimester Down syndrome (DS) maternal serum screening (T21T1) for the use of cell-free DNA (cfDNA) as a second-tier test in the French context. METHOD: A cost-effectiveness analysis was performed on 108,121 singleton pregnancies using a simulation model. The threshold of T21T1 screening was ranged from 1/51 to 1/1,000 in steps of 1/50. The most relevant threshold was based on cost-effectiveness ratio (CER; costs = direct medical costs after T21T1 screening/ effectiveness = number of DS cases identified). RESULTS: In the sample, 161 cases of DS were identified. At the threshold of ≥ 1/50, 47.2% of total DS cases were diagnosed. In the simulation model, for a threshold ≥ 1/250, 73.9% of total DS cases were diagnosed, for ≥ 1/500, 78.8% and for ≥ 1/1,000, only two additional cases were diagnosed. The slope of the cost increase was slight from threshold ≥ 1/250 (978,634 €), then steep up to 1/500 (1,966,576 €) and increased exponentially to 1/1,000 (3,980,216 €). The CER was 38,560 for a threshold ≥ 1/500. CONCLUSION: The most cost-effective threshold for cfDNA as a second-tier test seems to be ≥ 1/500. For higher thresholds, costs increase dramatically for only a few additional cases of DS identified.

[Potential value of placental angiogenic factors as biomarkers in preeclampsia for clinical physicians]. / Intérêts potentiels des facteurs angiogéniques placentaires comme biomarqueurs dans la pré-éclampsie pour le clinicien.

The role of angiogenic factors in the onset of clinical manifestations of preeclampsia was demonstrated in 2003 by the implication of sFlt-1, PlGF and VEGF, and in 2006 by the implication of soluble endoglin. Placental ischemia and inflammation observed in preeclampsia alter both the production and progression of angiogenic factors during pregnancy. During the first trimester, the combination of PlGF with clinical, biophysical and biological factors results in a better test than the conventional one. However, the clinical value of this method remains to be confirmed. During the second and third trimesters, the sFlt-1/PlGF ratio may be used, with or without pre-existing renal disease, for short-term prediction, diagnosis, and prognosis, and to evaluate the effectiveness of preeclampsia treatment. While a sFlt-1/PlGF ratio<38 and≤33, respectively, rules out the short-term onset and diagnosis of preeclampsia, a sFlt-1/PlGF ratio≥85 between 20 and 34 weeks of pregnancy and≥110 beyond 34 weeks of pregnancy confirms a diagnosis of preeclampsia. Angiogenic and non-angiogenic preeclampsia are identified by a sFlt-1PlGF≥85 and<85, respectively, with the risk of maternal and fetal complications at two weeks differing between the two. Similarly, a sFlt-1/PlGF ratio>665 and>205, respectively, is a good short-term predictor of adverse outcomes of early and late-onset preeclampsia. These values could be incorporated into future guidelines for better clinical management of preeclampsia.

Down syndrome maternal serum markers in oocyte donation and other assisted reproductive technologies.

OBJECTIVE: Because maternal serum markers (pregnancy-associated plasma protein A, human chorionic gonadotropin free ß subunit, and alpha-fetoprotein) used for Down syndrome (DS) screening have been described as predictors of obstetrical complications and because assisted reproductive technology (ART) pregnancies are known to be at increased risk for obstetrical complications, it is unclear whether or not correction factors should be applied to the calculated risk of DS. The purpose of this study was to evaluate DS maternal serum markers in oocyte donation (OD) and ART pregnancies in comparison with natural pregnancies. METHOD: Multicenter retrospective 2010 to 2013 study in singleton pregnancies was used. First- and second-trimester DS screenings in 614 OD and 1921 ART pregnancies versus 7268 natural pregnancies are compared. RESULTS: There was a significant increase in hCGß in the OD group for both trimesters (first trimester: 1.28 MoM vs 1.02; P < .001 and second trimester: 1.32 MoM vs 1 MoM; P < .001). Pregnancy-associated plasma protein A was significantly lower in the ART group (0.92 and 1.02 MoM P < .001). CONCLUSION: Maternal serum markers for DS screening are significantly modified in ART and OD pregnancies. Because these markers are also markers for obstetrical complications, the rationale for applying correction factors is questionable.

Thyroglobulin assay in fluids from lymph node fine needle-aspiration washout: influence of pre-analytical conditions.

The aim of this study was to evaluate the pre-analytical factors contributing to uncertainty in thyroglobulin measurement in fluids from fine-needle aspiration (FNA) washout of cervical lymph nodes. We studied pre-analytical stability, in different conditions, of 41 samples prepared with concentrated solutions of thyroglobulin (FNA washout or certified standard) diluted in physiological saline solution or buffer containing 6% albumin. In this buffer, over time, no changes in thyroglobulin concentrations were observed in all storage conditions tested. In albumin free saline solution, thyroglobulin recovery rates depended on initial sample concentrations and on modalities of their conservation (in conventional storage tubes, recovery mean was 56% after 3 hours-storage at room temperature and 19% after 24 hours-storage for concentrations ranged from 2 to 183 µg/L; recovery was 95%, after 3 hours or 24 hours-storage at room temperature, for a concentration of 5,656 µg/L). We show here that these results are due to non-specific adsorption of thyroglobulin in storage tubes, which depends on sample protein concentrations. We also show that possible contamination of fluids from FNA washout by plasma proteins do not always adequately prevent this adsorption. In conclusion, non-specific adsorption in storage tubes strongly contributes to uncertainty in thyroglobulin measurement in physiological saline solution. It is therefore recommended, for FNA washout, to use a buffer containing proteins provided by the laboratory.

High fasting serum insulin level due to autoantibody interference in insulin immunoassay discloses autoimmune insulin syndrome: a case report.

Insulin-antibodies are a cause of misleading results in insulin immunoassays. They may also mediate deleterious blood glucose variations. A patient presented with overtiredness, recurrent episodes of sweating, dizziness and fainting fits. A fasting serum insulin assay performed on a Modular platform (Modular analytic E170, Roche Diagnostic, Meylan, France) showed a highly elevated value of 194.7 mIU/L, whereas on the same sample glucose and C-peptide levels were normal. Other immunometric insulin assays were performed, as well as antibodies anti-insulin radiobinding assay (RBA) and gel filtration chromatography (GFC). While complementary insulin assays yielded closer to normal fasting levels, the free insulin concentration assessed after PEG precipitation was 14.0 mIU/L and the RBA was positive. GFC revealed that most of the insulin was complexed with a 150 kDa molecule, corresponding to an immunoglobulin G (IgG). A high fasting serum insulin level in a patient with neuroglucopenic symptoms was related to a high insulin-antibody level, suggesting an insulin autoimmune syndrome.

Impact of Including or Removing Nuchal Translucency Measurement on the Detection and False-Positive Rates of First-Trimester Down Syndrome Screening.

INTRODUCTION: First-trimester Down syndrome (DS) screening combining maternal age, serum markers (pregnancy-associated plasma protein-A and beta-human chorionic gonadotropin) and nuchal translucency (NT) gives an 85% detection rate for a 5% false-positive rate. These results largely depend on quality assessment of biochemical markers and of NT. In routine practice, despite an ultrasound quality control organization, NT images can be considered inadequate. The aim of the study was to evaluate the consequences for risk calculation when NT measurement is not taken into account. MATERIAL AND METHOD: Comparison of detection and false-positive rates of first-trimester DS screening (PerkinElmer, Turku, Finland), with and without NT, based on a retrospective study of 117,126 patients including 274 trisomy 21-affected fetuses. NT was measured by more than 3,000 certified sonographers. RESULTS: There was no significant difference in detection rates between the two strategies including or excluding NT measurement (86.7 vs. 81.8%). However, there was a significant difference in the false-positive rates (2.23 vs. 9.97%, p < 0.001). DISCUSSION: Sonographers should be aware that removing NT from combined first-trimester screening would result in a 5-fold increase in false-positive rate to maintain the expected detection rates. This should be an incentive for maintaining quality in NT measurement.

Assay-specific decision limits for two new automated parathyroid hormone and 25-hydroxyvitamin D assays.

BACKGROUND: The recent development of nonradioactive automated assays for serum parathyroid hormone (PTH) and 25-hydroxyvitamin D (25OHD) has made measurement of these two hormones possible in many laboratories. In this study, we compared two new assays for PTH and 25OHD adapted on an automated analyzer, the LIAISON, with two manual immunoassays used worldwide. METHODS: We studied 228 osteoporotic patients, 927 healthy individuals, 38 patients with primary hyperparathyroidism, and 167 hemodialyzed patients. Serum PTH was measured with the Allegro and the LIAISON assays, and 25OHD was measured with DiaSorin RIA and the LIAISON assay. Regression analysis was used to calculate decision thresholds for the LIAISON assays that were equivalent to those of the Allegro PTH and DiaSorin 25OHD assays. RESULTS: The 25OHD concentrations obtained with the LIAISON assay and the RIA in osteoporotic patients were well correlated (r = 0.83; P <0.001). Regression and Bland-Altman analyses suggested that the LIAISON 25OHD assay reads lower than the DiaSorin RIA at low concentrations but higher at high concentrations. However, the cutoff (50 nmol/L) used in our laboratories to define vitamin D insufficiency with the DiaSorin RIA is applicable to the LIAISON 25OHD assay. In 927 healthy individuals, the 3rd-97th percentile intervals were 3-80 ng/L and 13-151 nmol/L for the LIAISON PTH and 25OHD concentrations, respectively. However, 506 individuals (54.6%) were vitamin D-insufficient; we therefore considered only the 421 individuals with a LIAISON 25OHD >50 nmol/L as eligible for the reference population for the LIAISON PTH assay. In this group, the 3rd-97th percentile interval for LIAISON PTH was 3-51 ng/L. Considering upper reference limits of 46 and 51 ng/L for the Allegro and LIAISON assays, respectively, the frequency of above-normal PTH concentrations in patients with primary hyperparathyroidism was similar in both assays. Regression analysis between serum PTH measured by the Allegro and LIAISON assays in 167 hemodialyzed patients and the corresponding Bland-Altman analysis of these data suggest that the LIAISON PTH assay tends to read higher than the Allegro assay at low concentrations but lower at high concentrations (>300 ng/L). CONCLUSIONS: Because clinical decision limits for both PTH and 25OHD should be assay specific, we propose equivalences between these assays and two manual assays used worldwide. These assay-specific decision limits should help potential users of the LIAISON PTH and 25OHD assays.

Medically assisted reproduction and second-trimester maternal serum marker screening for Down syndrome.

OBJECTIVES: To evaluate the effect of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) on total hCG, free ss-hCG, AFP and unconjugated estriol (uE3) used as markers for second-trimester Down syndrome maternal serum screening. METHODS: Second-trimester maternal sera from 1515 singleton pregnancies (970 by IVF, 545 by ICSI) were compared with control sera (21 014 cases). Free ss-hCG, total hCG, AFP and uE3 were compared between the control group and the medically assisted reproduction groups. The percentages of at-risk patients (>/=1/250) were also compared. RESULTS: No differences in values of the maternal serum markers were observed between the medically assisted and control groups. When maternal age was taken into account, the screen-positive rate for Down syndrome screening did not differ between the two groups. CONCLUSION: Patients undergoing assisted reproduction techniques can be counseled for maternal serum Down syndrome screening with the same efficacy as patients with naturally conceived pregnancies.

Very low alpha-fetoprotein in Down syndrome maternal serum screening.

OBJECTIVE: To establish the frequency of very low maternal serum AFP and to differentiate congenital AFP deficiency from those diseases known to be associated with low AFP. METHODS: AFP values below 2 microg/L and borderline values up to 3 microg/L were retrospectively analysed in 839 773 singleton pregnancies included in a programme for routine screening of trisomy 21 maternal serum markers. RESULTS: Serum AFP was undetectable (< or =2 microg/L) in 8 cases, giving a frequency of 1/105 000. The calculated risk of Down syndrome was > or =1/250 in 5 cases. Fetal karyotype was normal. Seven of these pregnancies went to term (39-41 weeks) uneventfully, and birth weight was normal (3050-4110 g). In the 8th case, fetal death occurred at 35 weeks due to severe maternal diabetes. AFP levels between 2.1 and 3.0 microg/L were noted in 7 other cases. The calculated risk of Down syndrome was > or =1/250 in 5 cases, and fetal karyotype was normal. Pregnancies went to term in 4 cases (33-41 weeks), and birth weight was normal (3000-3380 g). In 3 cases, low hCG (<0.6 MoM) was associated with low AFP, and fetal death occurred at 15 to 16 weeks. CONCLUSION: Once technical errors have been excluded (repeat assay in a second run, calcium assayed to exclude the interference of EDTA for fluorimetric methods, dilution to exclude interfering antibodies, running on an alternative analyser, checking a second sample), very low second-trimester maternal serum AFP should prompt ultrasound examination in order to check fetal viability. Congenital AFP deficiency, an extremely rare disorder (1/100 000), should be suspected. It has no consequences for fetal and infant development, and parents should be reassured.

Second trimester two-step trisomy 18 screening using maternal serum markers.

Trisomy 21 maternal serum marker screening has led to screening for other anomalies, including trisomy 18. Trisomy 18 is generally prenatally diagnosed because of major morphological defects. However, in up to 30% of cases ultrasound signs are unclear, and in most cases diagnosis is performed late in pregnancy. Of the different maternal serum markers, PAPP-A is now considered as the best for trisomy 18 screening. However, pregnancy-associated plasma protein A (PAPP-A) is of value in first trimester screening for trisomy 21, but not in the second trimester. We therefore propose a two-step screening strategy. Based on 45 trisomy 18 cases, we confirm the values of alpha-fetoprotein (AFP) (median 0.61 MoM), free beta-human chorionic gonadotrophin (beta-hCG) (median 0.24 MoM) and of PAPP-A (median 0.08 MoM). In the first step, a 0.5 MoM cut-off for AFP or for free beta-hCG resulted in detection of 37/45 trisomy 18 cases (82%) with a 10% false-positive rate. The second step consisted of the measurement of PAPP-A for all these false-positive cases. Using a PAPP-A cut-off of 0.5 MoM, all the 37 trisomy 18 cases were detected, but now with a 0.1-0.2% false-positive rate. Amniocentesis was only offered to these few patients. This two-step second trimester screening will be of value for patients who have not been included in first trimester screening based on nuchal translucency (NT) measurement combined with the first trimester markers, PAPP-A and free beta-hCG.