Prenatal Screening For Down Research Articles

Prospective study of prenatal screening for Down's syndrome with free beta human chorionic gonadotrophin.

To assess the value and impact of a screening programme for Down's syndrome that uses the two maternal serum markers: alpha fetoprotein and free beta human chorionic gonadotrophin. All women booked into clinics were screened. Further tests were offered to women with a risk of one in 300 or greater of having an affected baby. Follow up of outcome of all pregnancies. Biochemical screening laboratory serving two health districts. 8179 women of all ages with singleton pregnancies screened between 15 and 22 weeks' gestation from 1 April 1991 to 31 March 1992. Detection rate of Down's syndrome, false positive rate, uptake of screening, uptake of amniocentesis in women identified as at increased risk, prevalence of Down's syndrome at birth. Overall 89% (8317/9345) of women underwent screening. The rate of detection of Down's syndrome was 69% (11/16; 95% confidence interval 41 to 89%) with a 5.2% false positive rate (426/179; 4.7 to 5.7%). In women under 30 the detection rate was 50% (four out of eight; 32 to 86%) Uptake of amniocentesis was 89% (389/437), resulting in a reduction of prevalence of Down's syndrome at birth from 1.1 per 1000 in previous years (66/59,696) to 0.4 per 1000 during the screening year (4/9345). Additionally, several other abnormalities were identified. The benefit of a high detection rate with this approach and the additional anomalies identified should encourage others to introduce screening programmes for Down's syndrome that use free beta human chorionic gonadotrophin and alpha fetoprotein.

Analyse critique de méthodes d'évaluation économique des actions de santé : l'exemple du dépistage prénatal de la trisomie 21

Valérie Séror: A critical analysis of methods of economie evaluation of public health intervention: the example of prenatal screening for Down's syndrome. Methodologies stemed from public economies field are more and more frequently used in order to assess health care public policies. While these evaluation studies are working towards the development of standardized methodologies, theorical and empirical difficulties still remain. This paper considers economie concepts underlying the measure of costs and health consequences as effectiveness and benefit. After a brief account of the different tools at the economiste disposal, emphasis will be put on identification and measurement of allocated resources in the way of comparability of economie evaluations. A special attention will be given to consequences identification and assessment, according to cost effectiveness and cost-benefit analysis principles. The latter will be analyzed according to social rentability perspectives and willingness-to-pay as an integrative tool of individual preferences. Contributions resulting of the use of economie evaluation methodologies in health care, as well as theorical and empirical difficulties will be discussed in the special case of Down's syndrome prevention, a particularly illustrative example.

Prenatal Screening for Down's Syndrome with Use of Maternal Serum Markers

Approximately 35 percent of all cases of Down's syndrome in fetuses can be detected by measuring maternal serum alpha-fetoprotein during the second trimester in the general population of pregnant women. Recent case-control studies indicate that this detection rate could be approximately doubled by measuring serum levels of unconjugated estriol and chorionic gonadotropin, which are abnormally low and abnormally high, respectively, in women carrying fetuses affected by Down's syndrome. We prospectively screened 25,207 women and adolescents in the second trimester of pregnancy and assigned each a risk of fetal Down's syndrome with an algorithm that took into account measurements of all three serum markers in combination with maternal age. On this basis, 1661 subjects (6.6 percent) were initially assigned a second-trimester risk of fetal Down's syndrome of at least 1 in 190, and 962 (3.8 percent) were offered amniocentesis for chromosomal analysis after verification of gestational age. Gestational age was determined on the basis of the first day of the last menstrual period or, when available, by ultrasonography. Among the 760 women and adolescents who chose amniocentesis, 20 cases of fetal Down's syndrome were detected, along with 7 other chromosomal disorders. There was 1 additional case of fetal Down's syndrome among the 202 women who chose not to have amniocentesis. The rate of detection of Down's syndrome was thus 58 percent (21 of 36 expected cases), and the frequency of identifying a fetus with Down's syndrome in women undergoing amniocentesis was 1 per 38 amniocenteses (95 percent confidence interval, 1 in 25 to 1 in 62). Measuring serum alpha-fetoprotein, chorionic gonadotropin, and estriol is more effective in screening for fetal Down's syndrome than measuring maternal serum alpha-fetoprotein alone. Such an expanded protocol can readily be incorporated into existing prenatal screening programs.

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.

Sir,?In the light of recent evidence that the test is a good predictor of Down's syndrome we write to express our concern that this investiga? tion is not generally available on the NHS.1 All women in Stockport are offered an estimation of a fetoprotein concentration and an ultrasound scan at 16 weeks of pregnancy. On the advice of one of the local consultant obstetricians a patient of ours with a low a fetoprotein concentration (17 u.g/1) was offered a triple test at the cost of ?50. We consider that if this investigation is recom? mended for the detection of Down's syndrome and has become a part of accepted medical practice it is indefensible not to offer it to an at risk woman and it is wrong that, depending on the area of the country in which the woman lives, the investigation is either free or not. Is this further evidence of inequality of health care or just the result of market forces? MJSTONE S F LEVY W TAIT P J ALLAN P J RILEY Hazel Grove, Stockport SK7 4QR

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.

Prenatal Screening for Down's syndrome: Authors' reply

Prenatal Screening for Down's syndrome: Authors' reply

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Prenatal screening for Down's syndrome

Who should be offered prenatal screening for Down's syndrome?

Who should be offered prenatal screening for Down's syndrome?

Appraisal of a new scheme for prenatal screening for Down's syndrome.

To appraise a new method of prenatal screening for Down's syndrome based on maternal serum concentrations of alpha fetoprotein, unconjugated oestriol, and human chorionic gonadotrophin combined with maternal age--the "triple test." Examination of the cost effectiveness of the triple test relative to screening only by maternal age over a range of population detection rates. Leicestershire Health Authority. Costs per affected fetus detected. The triple test is more cost effective than screening only by maternal age for risk cut off points for amniocentesis, resulting in a detection rate over 45%. The most efficient detection rate is around 60-65%, for which the cost per case detected is around 29,000 pounds, through screening with higher detection rates is still likely to be cost beneficial. Prenatal screening for Down's syndrome based on the triple test should replace screening based only on maternal age. Individual women's preferences should be elicited by the use of structured decision analysis in order to maximise utility and so increase the benefits of the screening programme.

Alphafetoprotein in midtrimester Down's syndrome fetal serum.

Serum alphafetoprotein was estimated in fetuses with and without Down's syndrome or with other chromosome abnormalities from the 17th to the 28th week of pregnancy. In normal fetuses, the AFP level declines steadily during this period. Before 20 weeks, there was no difference in the serum AFP levels of the three groups of fetuses. After 20 weeks, the serum AFP level in cases of Down's syndrome declined more rapidly than normal. This was not observed in fetuses with other chromosome abnormalities. This suggests that low maternal serum alphafetoprotein levels used for prenatal screening for Down's syndrome in the early second trimester cannot be explained by low levels in the Down's fetuses themselves.

Prenatal screening for Down's syndrome.

Prenatal screening for Down's syndrome.