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αlpha now includes the facility to calculate screening performance estimates for the sequential test using the age distribution in your screened population or using the age distribution of maternities in England and Wales (See reference below). These results can be compared with the observed positive rates in your screening program and corrective action taken if necessary.

For tests including first trimester markers, αlpha can now calculate the screening performance at 11, 12 or 13 weeks of gestation. αlpha can also calculate the screening performance for your screened population based on the actual distribution of weeks in which the first stage of the test was carried out. See examples of the performances tables produced by αlpha here.

αlpha now includes the age distribution of maternities in England and Wales for 2004 to 2006.

αlpha now includes adjustment factors for:

smoking for first trimester PAPP-A and total hCG and second trimester total hCG
IVF for first trimester PAPP-A.
twin pregnancies for first trimester total hCG

αlpha generates graphs showing MoM values against gestation and weight adjusted MoM values against weight. This is useful to visualise whether the MoM value is being calculated accurately over the whole range of gestational ages and weights Click here to see an example of this.

In IVF pregnancies, eggs can be collected, fertilised and frozen and then implanted several years later. αlpha now provides separate dates for date of egg collection and date of embryo transfer to allow appropriate adjustments to the mother or donor’s age at the expected date of delivery.

αlpha now includes the equation recommended by the UK Fetal Anomaly Screening Program (FASP) as one of the options for converting between CRL and gestational age. ( Loughna P, Chitty L, Evans T, Chudleigh T (2009). Fetal size and dating: charts recommended for clinical obstetric practice. Ultrasound 17, 161-167)

αlpha can be used to interpret sequential testing which allows early completion of screening for women with very high risk pregnancies identified in the first trimester. A high risk cut-off is set for the first trimester test so there is a low false positive rate. Information on pregnancies that are not positive in the first trimester test are held for use in an integrated test without reporting a first trimester result. Nearly all women proceed to the full Integrated test. For further information on the sequential test see: Wald NJ, Rudnicka AR and Bestwick JP (2006) Sequential and contingent prenatal screening for Down’s syndrome Prenat Diagn 26 769-777

αlpha can identify cases where a single marker has a very large influence on the risk estimate raising the possibility that the risk estimate may be incorrect . In these cases, αlpha will notify the user of the anomalous marker and give them the opportunity of removing it from the risk estimate in the screening report. For further information see: Wald NJ, Bestwick JP, Barnes IM, Kellner LH (2007) Anomalous marker patterns in Down syndrome screening Prenat Diagn 27:185–186

Click here to see an example of a report showing the risk estimate diagram. (This opens in a separate window as a PDF document).

Before all women who had a non-inherited pregnancy with Down's syndrome had their calculated risk increased by an additional "6 per 1000" risk. Recent work shows that the additional risk is higher if the previous affected pregnancy occurred at a young age and lower if at an older age (Morris KJ, Mutton DE, Alberman E (2005) Recurrences of free Trisomy 21:analysis of the data from the National Down Syndrome Cytogenetic Register Prenat Diagn 25, 1120-1128). The age specific risk is now used.

αlpha includes a facility which provides simple monitoring of sonographer or site specific nuchal translucency medians. This will be useful for users who need to regularly monitor NT medians for a large group of sonographers. A sonographer can be selected from a list and a graph showing the measurements is immediately shown together with the number of scans performed, median MoM NT value, standard deviation and percentage increase per week. Click here to see an example.

An arithmetic (non-log) linear equation or a log-linear equation can be chosen for the regression equations relating expected median uE3 level to gestational age. Previously only a log-linear equation was available. The linear equation may provide a better to fit to observed uE3 measurements with gestational age than the log-linear equation.

A log-cubic equation (Wald NJ, Bestwick JP, Huttly WJ (2008) Inhibin-A concentrations between 14 and 22 weeks of gestation Prenat Diagn 2008; 28: 360–361) or log-quadratic equation can be chosen for regression equations relating expected median inhibin-A level to gestational age. Previously only a log-quadratic equation was available. The log-cubic equation may provide a better to fit to observed inhibin-A measurements with gestational age than the log-quadratic equation.

αlpha includes a facility to allow the current regression equation relating expected marker value to gestational age to be compared with a regression equation fitted to tabulated data. This feature is useful when updating median values because it will show how much change there has been in the normal median equations since they were last updated.

An example of this is given here. This shows a regression of median PAPP-A with gestational age. The open circles are the measured median values from recent measurements and the red line is the fitted regression equation to these values. The green line is the regression equation which is currently in use to estimate the expected PAPP-A value and shows that it will underestimate this value beyond about 85 days of gestation.

αlpha uses new statistical parameters (means, standard deviations and correlation coefficients of the screening markers) in estimating a woman’s risk of having a pregnancy affected with Down’s syndrome. The new parameters are derived from the Serum, Urine and Ultrasound Screening Study (SURUSS)

αlpha uses revised estimates of the age specific live birth prevalence of Down’s syndrome based on the UK National Down's syndrome cytogenetic register (Morris JK, Mutton DE, Alberman E (2005). Corrections to maternal age-specific live birth prevalence of Down’s syndrome. J Med Screen 12, 202)

αlpha uses a new approach in the interpretation of screening tests for twin pregnancies that include ultrasound markers (nuchal translucency and/or absent nasal bone). (Wald NJ, Rish S (2005). Prenatal screening for Down syndrome and neural tube defects in twin pregnancies. Prenat Diagn 25, 740-745)

αlpha can include information on the presence or absence of fetal nasal bone in the interpretation for Down’s syndrome.

A woman who has a false-positive screening result in one pregnancy is much more likely to have one in a subsequent pregnancy than women in general. αlpha deals with this problem by adjusting serum markers in women who have been screened in a previous pregnancy and who have not had a previous pregnancy with Down’s syndrome. At present there is insufficient information to carry this out adjustment with total hCG but the ability to do this will be included when the information is available. (Wald NJ, Barnes IM, Birger R, Huttly W (2006). Effect on Down syndrome screening performance of adjusting for marker levels in a previous pregnancy. Prenat Diagn 26, 539-544)

Provides a feature, Analyze-It™, which offers great flexibility and power to users who wish to perform their own statistical analyses on data from their screening database. Powerful selection criteria help the user to focus on the data of interest, which can be sorted by any column. Data can be exported directly to Microsoft Excel spreadsheets, or, via comma-separated value (CSV) files, to a wide range of other databases and statistical software. Analyze-It™ queries can be organised by project in hierarchical folders.

αlpha Outcome is now supplied as a standard feature in αlpha. It allows users to record pregnancy outcomes and to validate their screening program by plotting a graph of the observed Down's syndrome prevalence according to the median risk in groups of pregnancy ranked by the predicted risk. For more information, please click here.