Estimation du risque de trisomie 21 fœtale par les marqueurs sériques maternels. Étude du facteur tabac

Smoking habits may affect the calculated risk of Down's syndrome (DS). The effect of smoking increases αFP and decreases hCG. The aim of our study is to obtain correction factors for smokers, as well as to discuss the properties of these factors, the way to obtain them and the impact on DS risk. The magnitude of correction factors we found are of 20% for hCG and 2% for αFP. The amplitude of correction strongly depend on the nature of the population used to define the mathematical models for medians: heterogeneous population (smoking and non smoking) or homogeneous (non smoking). The overall consequence on the screening performance is moderate but still remains significant at the level of each individual.