Performance of first-trimester combined test for Down syndrome in different maternal age groups: reason for adjustments in screening policy?
OBJECTIVE
To evaluate the performance of the first-trimester combined test (FCT) in different maternal age groups and to discuss whether adjustments in screening policies should be made.


METHODS
In this retrospective study data (n = 26 274) from a fetal medicine center on FCT (maternal age, fetal NT, free β-human chorionic gonadotrophin, pregnancy-associated plasma protein-A) were studied.


RESULTS
70.6% of cases was <36 years and 43% of the Down syndrome (DS) cases were detected in this age group. For women <36 years and advanced maternal age (AMA) women (≥36 years) detection rate (DR) and false positive rate (FPR) were 94.5% and 4.1%, and 95.8% and 13.0%, respectively (cut-off 1:200). Lowering the cut-off showed an improved balance in DR and FPR. With increasing maternal age FPR and DR increased and odds of being affected given a positive result (OAPR) decreased.


CONCLUSIONS
FCT is effective in women <36 and ≥36 years. The balance between FPR and DR is more favourable in women <36 years with comparable OAPR. Although FPR increases with increasing maternal age, performance of FCT in AMA women is more effective than screening based on maternal age alone. Lowering the cut-off to 1:100 in AMA women is suggested to improve screening performance. Routinely offering diagnostic testing to AMA women as a screening policy for the detection of DS seems not reasonable.
Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, The Netherlands. m.engels@vumc.nl
Melanie A J
MA
Engels
A C
AC
Heijboer
Marinus A
MA
Blankenstein
John M G
JM
van Vugt
D000328:Adult; D000367:Age Factors; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008875:Middle Aged; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity
D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A