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Table 5 Predictive values of maternal free β- hCG, AFP MoM, and risk value of Trisomy 21 for Trisomy 21

From: New cut-off values for screening of trisomy 21, 18 and open neural tube defects (ONTD) during the second trimester in pregnant women with advanced maternal age

Group or item N AUC 95%CI P cut-off Sensitivity Specificity Youden index
Non-AMA 197,101        
 free β- hCG (MoM)   0.784 0.703–0.865 < 0.001 2.055 0.675 0.881 0.506
 AFP (MoM)   0.699 0.618–0.779 < 0.001 0.795 0.675 0.760 0.385
 Risk value of Trisomy 21   0.856 0.792–0.920 < 0.001 1/780 0.792 0.862 0.654
AMA 12,739        
 free β- hCG (MoM)   0.783 0.680–0.885 < 0.001 1.725 0.679 0.805 0.483
 AFP (MoM)   0.767 0.668–0.865 < 0.001 0.925 0.821 0.656 0.477
 Risk value of Trisomy 21   0.858 0.780–0.936 < 0.001 1/172 0.714 0.866 0.580
  1. AMA advanced maternal age, AFP alpha-fetoprotein, free β-hCG free beta human chorionic gonadotropin, MoM multiple of the median