[Screening and prevention of preeclampsia using the Fetal Medicine Foundation algorithm]

In order to identify women at high risk of pre-eclampsia and offer them aspirin prophylactic treatment, the Fetal Medicine Foundation (FMF) recommends a first-trimester screening test. The commonly used threshold for aspirin administration is a risk >1/100, which implies treating an important number of patients. We aimed to assess the use of this strategy with a more restrictive threshold: risk >1/70 and evaluate the impact of this strategy on the prevalence of pre-eclampsia with premature delivery in nulliparous women.

A before-and-after cohort study conducted from 01/09/2014 to 01/12/2018, including nulliparous women undergoing first-trimester ultrasound at the University Hospital of Toulouse. Between 09/2014 and 09/2016 ("before cohort"), women did not undergo pre-eclampsia screening. Between 01/2017 and 12/2018 ("after cohort"), women underwent targeted pre-eclampsia screening using the FMF algorithm, and those with a risk >1/70 received 100mg aspirin. The primary outcome was pre-eclampsia with premature delivery. A univariate and then a multivariate analysis were performed to take into account potential confounding factors.

Among the 1030 women of the before cohort, 17 women (1.7%) experienced pre-eclampsia with premature delivery, compared to 8 women (1.3%) among the 629 of the after cohort, with no significant difference between the two groups (Adjusted Odd Ratio (95%CI)=0.73 [0.31-1.74]). In the after cohort, 18 women (2.9%) had a risk greater than 1/70 and therefore received aspirin. According to the FMF screening test, 89 women (14.1%) had a risk>1/100, which is the usual threshold for prescribing aspirin for prophylaxis. This means that 71 women had a risk greater than 1/100 but less than 1/70 and therefore did not receive aspirin in this study, even though they would have received aspirin at the usual threshold.

The screening and prevention strategy for pre-eclampsia using restrictive thresholds did not decrease the rate of preeclampsia with premature delivery.