A comparison of total and free β‐HCG assays in Down syndrome screening

Stone, S; Henley, R; Reynolds, Tim; John, Rhys

doi:10.1002/pd.1970130617

Cited by 19 publications

(5 citation statements)

References 5 publications

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“…Most centres began recruiting in September 1996, following a pilot study started in January 1995 at one centre. Recruitment to the study ended in April 2000, and follow-up of pregnancy outcome was carried out to 31 May 2001.…”

Section: Test (All Include Measurements Fpr For 85% Dr 95% Confidencementioning

confidence: 99%

First and second trimester antenatal screening for Down's syndrome: the results of the Serum, Urine and Ultrasound Screening Study (SURUSS)

Wald¹,

Rodeck

Hackshaw³

et al. 2003

Health Technol Assess

453

390

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Section: Test (All Include Measurements Fpr For 85% Dr 95% Confidencementioning

confidence: 99%

First and second trimester antenatal screening for Down's syndrome: the results of the Serum, Urine and Ultrasound Screening Study (SURUSS)

Wald¹,

Rodeck

Hackshaw³

et al. 2003

Health Technol Assess

453

390

View full text Add to dashboard Cite

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“…Down's Mean or median syndrome (MOM) AFP Wald and Cuckle, 1992Spencer, 1991Ryall et al, 1992Hagenaars et al, 1992Spencer and Macri, 1992Stone et ab, 1993Nerrgaard-Pedersen et al, 1993 Geometric mean* uE3 Wald and Cuckle, 1992Spencer, 1991Ryall et al, 1992Hagenaars et al, 1992Crossley et al, 1993 Geometric mean* hCG Wald and Cuckle, 1992Spencer, 1991Ryall et al, 1992Hagenaars et al, 1992Seror et al, 1993Stone et al, 1993Nargaard-Pedersen et al, 1993 Geometric mean* Free P-hCG Macri et al, 1990Spencer, 199 1 Crossley et al, 1991aRyall et al, 1992Spencer and Macri, 1992Stone et al, 1993Wald et al, 1993bNerrgaard-Pedersen et al, 1993…”

Section: Studymentioning

confidence: 99%

Improved parameters for risk estimation in Down's syndrome screening

Cuckle

1995

Prenatal Diagnosis

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A new method is described for calculating maternal serum marker distribution parameters which will improve risk estimation when screening for Down's syndrome. The approach is to calculate parameters using data from the local screened population and data obtained by meta-analysis from all published studies. The local data are used to derive the variance and covariance in unaffected pregnancies. The meta-analysis is used for the mean level in Down's syndrome pregnancies together with the differences in variance and covariance between affected and unaffected pregnancies. Forty-four published studies were analysed. The mean level for Down's syndrome in multiples of the normal median was 0.73 for alpha-fetoprotein (AFP) in total of 1140 pregnancies, 0.73 for unconjugated oestriol (uE3) in 613, 2.02 for human chorionic gonadotropin (hCG) in 850, and 2.30 for free beta-hCG in 477. For all four markers, the variance in Down's syndrome was higher than in unaffected pregnancies; for AFP and uE3, the covariances were also higher in Down's syndrome, but for the other markers they were lower. The method was illustrated using data from 6387 pregnancies screened in Leeds.

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“…Provided that the variances are the same for free-β and intact-β, detection rates using free-β should be superior to those of intact hCG, and figures as high as 77% have been claimed for the combination of free-β with AFP and age [139]. The superiority of free-β to intact hCG has been disputed by WALD and colleagues [158,159] and others [96,145]. Another problem is that intact hCG in serum can break down on storage to generate free-[56, 144,170].…”

Section: The Place Of Oestriolmentioning

confidence: 99%

Review article

Chard

Macintosh²

1995

Jpme

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Down's syndrome (DS) is the commonest cause of severe mental retardation in children. It is the result of trisomy of chromosome 21 which is usually a random event though it is commoner in older mothers. DS can be diagnosed by chorionic villus sampling (CVS) and amniocentesis followed by karyotyping. Because of the risks associated with these invasive procedures, they can only be offered to a high-risk group. At one time the sole basis for identifying this increased risk was maternal age, but within the past ten years a series of biochemical and ultrasound abnormalities have been shown in DS pregnancies. The biochemical abnormalities include changes in the levels of most fetal and placental products in the maternal circulation. The best-known of these changes are the reduced levels of alphafetoprotein (AFP) and oestriol (E3) and increased levels of human chorionic gonadotrophin (hCG). The mechanism underlying these biochemical phenomena is unknown. Screening programmes involving the measurement of hCG and AFP, with or without additional parameters such as E3, at 15-18 weeks of pregnancy can typically identify 60% or more of cases of DS with a screen-positive rate of 5%. The combined risk derived from the various biochemical parameters, together with maternal age, is calculated by one of a number of computer programmes which have been developed for this purpose. There has been considerable discussion as to the exact biochemical tests which should be used for DS screening. This had led to controversy as to whether measurement of E3 has a place, and whether or not measurement of the free beta-subunit of hCG should replace measurement of the intact molecule. A notable recent development is the suggestion that measurement of the urinary beta-core of the hCG could be a highly discriminatory marker. A number of factors can affect the results of biochemical screening for DS. These include maternal weight, gestational age, ethnic origin, smoking, and diabetes. In addition, abnormal levels of the biochemical products may be found in other chromosome abnormalities.

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A comparison of total and free β‐HCG assays in Down syndrome screening

Cited by 19 publications

References 5 publications

First and second trimester antenatal screening for Down's syndrome: the results of the Serum, Urine and Ultrasound Screening Study (SURUSS)

First and second trimester antenatal screening for Down's syndrome: the results of the Serum, Urine and Ultrasound Screening Study (SURUSS)

Improved parameters for risk estimation in Down's syndrome screening

Review article

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