performance and predictive value of first trimester screening markers for down syndrome in iranian pregnancies

Objective: to investigate the performance of first trimester down syndrome (ds) screening markers in iranian pregnancies.although sonographic and serum markers are currently recommended for the first trimester screening of down syndrome, the screening performance of the markers depends on the race and ethnicity.materials and methods: a retrospective casecontrol study using first trimester screening results recorded with the prenatal diagnostic multicenters in iran. a total of 6,384 pregnant women were examined from march 2012 to february 2017. totally 100 down syndrome cases and 266 matched controls were selected and the maternal characteristics, sonographic and biochemical screening data were collected. statistical analysis was performed using logistic regression and descriptive statistics. a decision tree model was designed using the chisquared automatic interaction detection method based on serum markers.results: for screening of ds pregnancies, pappa (cut-off 0.795 mom) yielded the highest sensitivity (86%) and nb marker presented highest specificity (96.24%). combination of the biochemical markers pappa and βhcg (cutoff: 1.55 mom) showed the highest sensitivity over other combined markers. the decisiontree model based on serum markers improved (91% dr for a 5% fpr) first trimester screening performance.conclusion: the novel decisiontree model base on serum markers revealed a better predictive value to achieve high sensitivity and specificity of first trimester down syndrome screening in iranian population.