Maternal serum alpha-fetoprotein levels in pregnancies among black and white women with fetal open spina bifida: a United States collaborative study

Serum alpha-fetoprotein levels in patients with advanced hepatitis C: results from the HALT-C Trial

BACKGROUND/AIMS

Alpha-fetoprotein (AFP) has been useful in the diagnosis of hepatocellular carcinoma (HCC) but lacks specificity. We assessed serum AFP among patients with chronic hepatitis C and advanced fibrosis to establish predictors of AFP elevations and changes with antiviral therapy.

METHODS

Serum AFP was measured at baseline and on therapy in patients in the Hepatitis C Antiviral Long-Term Treatment against Cirrhosis (HALT-C). AFP levels were correlated with patient demographic and clinical features.

RESULTS

Baseline AFP was > or = 20 ng/mL in 191 of 1145 patients (16.6%). Mean AFP values were significantly higher in patients with cirrhosis than in those with bridging fibrosis (22.5 vs. 11.4 ng/mL, P < 0.0001). Factors independently associated with raised serum AFP in patients with cirrhosis were female gender, black race, decreased platelet count, increased serum AST/ALT ratio, serum ferritin, and Mallory bodies in liver biopsies. Serum AFP levels decreased significantly during therapy with pegylated interferon alpha-2a and ribavirin. HCC was identified in six subjects, only three of whom had AFP > 20 ng/mL.

CONCLUSIONS

Among patients with advanced chronic hepatitis C, serum AFP values are frequently elevated, even in the absence of HCC. Factors associated with raised AFP include severity of liver disease, female gender and black race. Serum AFP levels decline during antiviral therapy.

Triple-marker test as screening for Down syndrome: a meta-analysis

The effectiveness of triple-marker testing as screening for Down syndrome needs to be evaluated by means of formal meta-analytic techniques. We did a MEDLINE search to identify studies evaluating the detection of Down syndrome by use of the triple-marker test. Reference lists of articles were also checked. Papers published in either English, French, or German from 1966 to November 1996 were eligible for this review. Twenty cohort studies were identified. Results of sensitivities and false-positive rates from different subgroups of the study sample were compared by using summary receiver-operating characteristic curve analysis. Medians of sensitivities and false-positive rates were also estimated. A total of 194,326 patients were included. In women of all ages, the medians for sensitivities were 67, 71, and 73 percent when the cutoffs used were 1:190-200, 1:250-295, and 1:350-380, respectively. The median false-positive rates fluctuated between 4 and 8 percent. For women at or above 35 years old, the medians of sensitivity and false-positive rate were 89 and 25 percent, respectively, when the chosen cutoff was 1:190-200. In patients below 35 years old, the median sensitivity was 57 percent if the cutoff used was 1:250-295. Summary receiver-operating characteristic curves showed that 1:190 was the best cutoff for predicting Down syndrome. The triple-marker testing is an effective screening method of detecting Down syndrome pregnancies. It is less effective in younger than in older age groups and may be offered as an alternative to amniocentesis to pregnant women over 35.

Prenatal diagnosis of diverse chromosome abnormalities in a population of patients identified by triple-marker testing as screen positive for Down syndrome

OBJECTIVE

Our purpose was to determine the incidence of all types of chromosome abnormalities (i.e., trisomy 21 and other abnormalities) in women receiving prenatal chromosome analysis after a Down syndrome screen-positive result by maternal serum triple-marker testing (alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol analyses).

STUDY DESIGN

A total of 11,434 patients between 15.0 and 21.9 weeks' gestation received second-trimester Down syndrome risk evaluation by triple-marker testing. By use of a 1:270 midtrimester Down syndrome risk cutoff value, and after ultrasonographic confirmation of gestational age, 677 patients were screen positive for Down syndrome (corrected screen-positive rate 5.92%). Karyotypes were reviewed for 468 (69%) of these patients who received prenatal chromosome analysis.

RESULTS

In addition to 12 cases of Down syndrome, 12 other fetal chromosome abnormalities were found (i.e., 5.13% had a chromosome abnormality of some type). Expressed as a proportion of all patients with a corrected Down syndrome screen-positive result, at least 3.69% had a chromosome abnormality. The overall spectrum of abnormal karyotypes (approximately 50% autosomal trisomy, 25% structural and 25% sex chromosome abnormality) appears to be comparable to that seen in patients undergoing amniocentesis because of advanced maternal age.

CONCLUSIONS

As is the case for women of advanced maternal age, preamniocentesis counseling for patients with positive triple-marker testing results should reflect the relatively high probability that an abnormality other than Down syndrome may be identified.

Effect of parity on human chorionic gonadotrophin levels and Down's syndrome screening

OBJECTIVE

To investigate further the association between parity and human chorionic gonadotrophin (hCG) levels during the second trimester and determine whether prenatal screening for Down's syndrome might be made more efficient by adjusting for this variable.

METHODS

Measurements of hCG were analysed in relation to parity from a cohort of 16,675 singleton pregnancies with viable outcomes, and from 108 singleton pregnancies affected by Down's syndrome. Cigarette smoking during pregnancy and maternal age were also analysed in relation to hCG levels.

RESULTS

For both unaffected pregnancies and pregnancies with Down's syndrome the median hCG levels were 7% lower in parous than in nulliparous women. A dose-response relation was also documented for the unaffected pregnancies. When para 0, para 1, and para 2 women were studied separately, hCG levels rose steadily as age advanced. Adjusting hCG levels for parity led to a 0.1% reduction in variance of the distribution of hCG measurements in unaffected pregnancies and to a negligible increase in Down's syndrome screening efficiency.

CONCLUSION

The effect of parity is not sufficiently great to warrant routine adjustment of hCG levels as part of prenatal screening for Down's syndrome.

Laboratory screening for genetic disorders and birth defects

Screening for inherited disease is a preventative health measure that started in the 1960s with the development of programs for the detection of PKU in newborns and that has had a major impact on reducing the burden of disease. Developments in technology have led to the availability of large scale testing for an increasing number of both acquired and genetic disorders. Laboratory testing is only one facet of a screening program and consideration should be given to availability of testing to all individuals, education regarding the program, effectiveness of treatment, long-term benefits both for individuals and society, ethical issues, and cost benefits. In this review, newborn, prenatal, and heterozygote screening are discussed.

Testing for fetal abnormality in routine antenatal care

The detection of fetal abnormality is a major component of routine antenatal care. A variety of techniques are now in use, although these are constantly being modified in the pursuit of more accurate and earlier detection. In this paper we draw attention to the distinction between screening and diagnostic tests, and describe the techniques which have been most commonly used in the UK: serum-screening for neural tube defects; screening for Down's syndrome; ultrasound scanning; amniocentesis and chorionic villus sampling.

The effect of adjusting maternal serum alpha-fetoprotein levels for maternal weight in pregnancies with fetal open spina bifida. A United States collaborative study

The effect of adjustment of maternal serum alpha-fetoprotein levels for maternal weight was evaluated in 143 pregnancies associated with fetal open spina bifida. The cases were analyzed with gestational dates as initially assigned either by last menstrual period (73%) or by ultrasonography (27%). The weights of women with pregnancies affected by open spina bifida were found not to be different from unaffected pregnancies. Adjustment resulted in a net increase in detected cases at two commonly used cutoff points: 2.0 and 2.5 multiples of the median. At 2.0 multiples of the median, the detection rate increased from 80% to 84%, whereas at 2.5 multiples of the median the rate rose from 68% to 69%. Adjustment for maternal weight has previously been shown to reduce the false-positive rate in maternal serum alpha-fetoprotein screening for fetal open spina bifida by reducing variance in unaffected pregnancies; our data provide further support for consideration of maternal weight when interpreting material serum alpha-fetoprotein measurements.