Autocorrelation and cross-correlation between hCGβ and PAPP-A in repeated sampling during first trimester of pregnancy

Pernille Nørgaard; Dave Wright; Susan Ball; Paul Newell; Ida Kirkegaard; Olav Bjørn Petersen; Niels Uldbjerg; Niels Tørring; Finn Stener Jørgensen; Lennart Friis-Hansen; Charlotte Ekelund; Ann Tabor; Steen Sørensen

doi:10.1515/cclm-2012-0805

Artikel

Autocorrelation and cross-correlation between hCGβ and PAPP-A in repeated sampling during first trimester of pregnancy

Pernille Nørgaard , Dave Wright , Susan Ball , Paul Newell , Ida Kirkegaard , Olav Bjørn Petersen , Niels Uldbjerg , Niels Tørring , Finn Stener Jørgensen , Lennart Friis-Hansen , Charlotte Ekelund , Ann Tabor und Steen Sørensen

Veröffentlicht/Copyright: 11. April 2013

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Aus der Zeitschrift Clinical Chemistry and Laboratory Medicine Band 51 Heft 9

Abstract

Background: Theoretically, repeated sampling of free β-human chorionic gonadotropin (hCGβ) and pregnancy associated plasma protein-A (PAPP-A) in the first trimester of pregnancy might improve performance of risk assessment of trisomy 21 (T21). To assess the performance of a screening test involving repeated measures of biochemical markers, correlations between markers must be estimated. The aims of this study were to calculate the autocorrelation and cross-correlation between hCGβ and PAPP-A in the first trimester of pregnancy and to investigate the possible impact of gestational age at the first sample and time between sampling on the correlation.

Methods: A prospective study was conducted including 3891 unaffected singleton pregnancies. Two measurements of hCGβ and PAPP-A were obtained during the first trimester in each pregnancy. Correlations between the four parameters, hCGβ first, hCGβ second, PAPP-A first and PAPP-A second, were estimated and presented in terms of Pearson’s r coefficients. Furthermore, the correlation between paired samples as a function of time between samples was investigated.

Results: The study demonstrated high correlation between first and second samples of hCGβ and PAPP-A with a correlation coefficient of 0.80 and 0.79, respectively. By contrast, the correlations between hCGβ and PAPP-A were low. In addition, the study demonstrated that the correlation between paired samples of hCGβ and PAPP-A decreases with earlier gestational age at the first sample and with increasing time between samples.

Conclusions: We have developed a parameter set in terms of correlations between biochemical markers, which can be incorporated into a T21 screening algorithm based on repeated measures within the first trimester.

Keywords: combined first trimester screening; correlation; Down syndrome screening; first trimester risk assessment; free β-human chorionic gonadotropin (hCGβ); pregnancy associated plasma protein-A (PAPP-A); repeated biochemical markers; Trisomy 21 screening

Corresponding author: Pernille Nørgaard, MD, Fetal Medicine Unit, Department of Obstetrics and Gynecology, Hvidovre Hospital, University of Copenhagen, Copenhagen 2650, Denmark

We are grateful for financial support from the Svend Andersen Foundation, Aase and Einar Danielsens Foundation and Johan and Lise Boserups Foundation.

Conflict of interest statement

Authors’ conflict of interest disclosure: The authors stated that there are no conflicts of interest regarding the publication of this article. Research support played no role in thestudy design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision tosubmit the report for publication.

Research funding: None declared.

Employment or leadership: None declared.

Honorarium: None declared.

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Received: 2012-11-24

Accepted: 2013-3-18

Published Online: 2013-04-11

Published in Print: 2013-09-01

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Artikel in diesem Heft

https://doi.org/10.1515/cclm-2012-0805

Schlagwörter für diesen Artikel

combined first trimester screening; correlation; Down syndrome screening; first trimester risk assessment; free β-human chorionic gonadotropin (hCGβ); pregnancy associated plasma protein-A (PAPP-A); repeated biochemical markers; Trisomy 21 screening