Impact of First-trimester Preeclampsia Screening on Perinatal and Maternal Morbidity : a Multicenter Randomized Trial

Preeclampsia (PE) complicates 2% of pregnancies and is a leading cause of severe maternal and perinatal complications. There is no curative treatment, and the only recognized beneficial primary prevention is low-dose aspirin. Meta-analyses of randomized trials show that the administration of aspirin, started before 16 weeks of gestation (WG) and at the dosage of 100-160 mg/d in pregnant women at high risk of PE, is associated with a 50% to 60% reduction in the rates of PE, prematurity and perinatal mortality. The group of patients benefiting most from aspirin is pregnant women with a history of PE. That is why all guidelines recommend early preventive administration of aspirin in pregnant women with PE in a previous pregnancy. However, patients with a history of PE represent a small fraction of pregnant women, and PE mostly occurs in women who do not have a history of PE, especially nulliparas. Recently, several national societies decided to broaden the indications for aspirin prevention on the basis of the number of known maternal risk factors. These recommendations lead to a wide use of low-dose aspirin in up to 30% of pregnant women. In order to better target patients at risk of PE among all pregnant women, screening tests have been developed integrating clinical characteristics, uterine Doppler (UD) parameters and biomarkers in a single score. The study by Poon et al. paved the way for early detection of PE. An algorithm based on maternal characteristics, UD parameters and serum levels of PlGF and PAPP-A between 11 and 14 WG yielded detection rates of 93% and 36% for the prediction of early- and late-onset PE, respectively, at 5% false-positive rate (FPR), which were superior to the detection rates of the traditional checklist-based approach, which relies on maternal factors only. This algorithm developed by the Fetal Medicine Foundation (FMF) has since evolved and is now integrated in the combined test for PE screening known as the FMF triple test (a combination of maternal characteristics with mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), and serum PlGF). In a subsequent study using a risk cutoff of 1 in 100 for the predicted probability of preterm PE, a screen-positive rate of 10% has been reported, with detection rates for early-onset, preterm, and term PE of 88%, 69%, and 40%, respectively.

Recently, the ASPRE study evaluated the impact of aspirin in patients identified at high risk of PE on the basis of this FMF test. Screening was offered to 26,941 women and identified 2,641 high-risk patients of whom 1,776 were randomized to aspirin or placebo. This trial showed a reduction in the incidence of PE <37 WG, occurring in 13/798 in the aspirin group versus 35/822 in the placebo group (p=0.004), but with no significant effect on the overall rate of PE and most importantly on perinatal morbidity. Screening had to be applied to almost 27,000 women for a benefit of 22 avoided cases of preterm PE, with no demonstrated effect on the health of the women and children. The ASPRE study is important but does not demonstrate the benefit of routinely implementing PE screening in the general population. Indeed, there is currently no randomized study comparing a group of women to which the screening procedure would be applied to a group of women without screening, the only design able to provide strong evidence of a benefit. In addition, implementing a national screening program in pregnant women may induce adverse events, especially iatrogenicity (more hospitalizations, more ultrasound examinations, more consultations) and anxiety. Such a screening program is also associated with an increase of direct and indirect health costs.

To consider implementing screening for PE in the general population, it is then essential to demonstrate its benefits on robust health outcomes and not only on the PE diagnosis, as well as to assess its potential adverse consequences and costs. This evaluation is all the more crucial since it is currently offered to an increasing number of women.

The RANSPRE study will therefore be the first trial to test the impact on perinatal and maternal health outcomes of first-trimester screening for preeclampsia associated with aspirin treatment of pregnant women screened at risk. A medical and economic evaluation allowing a cost-effectiveness analysis will also be carried out. The results of this study will constitute essential information relevant to the health care system that will guide policymaking for the prevention of PE in the general population of pregnant women.

The primary objective of the study is to evaluate the impact of first-trimester PE screening (FTPS) on the incidence of severe perinatal morbidity. The primary outcome will be severe perinatal morbidity defined by a composite criterion including at least one of the following: perinatal mortality (stillbirth at or after 20 WG or neonatal death within 7 days of life) or prematurity <34 WG or birth weight <3° percentile for gestational age.