The Implementation of Preeclampsia Screening and Prevention (IMPRESS) Study

BACKGROUND: Preeclampsia affects between 2% and 5% of preg-nancies and is one of the leading causes of perinatal morbidity and mortal-ity worldwide. Despite strong evidence that the combination of systematic preeclampsia screening based on the Fetal Medicine Foundation pre-eclampsia risk calculation algorithm with treatment of high-risk patients with low-dose aspirin reduces the incidence of preterm preeclampsia more than currently used risk-factor-based screening, real-world imple-mentation studies have not yet been done in Canada.OBJECTIVE: This study aimed to assess the operational feasibility of implementing first-trimester screening and prevention of preterm pre-eclampsia (<37 weeks) alongside a publicly funded first-trimester com-bined screening program for aneuploidies.STUDY DESIGN: This was a prospective implementation study. Consecu-tive pregnant patients referred for first-trimester combined screening (11-13 +6 weeks) were offered screening for preeclampsia based on the Fetal Medi-cine Foundation algorithm concomitantly with their aneuploidy screen. Consent-ing participants were screened using maternal risk factors, mean arterial pressure, uterine artery Doppler pulsatility index, pregnancy-associated plasma protein-A, and placental growth factor. Risk for preterm preeclampsia (<37 weeks) was calculated using the Fetal Medicine Foundation algorithm, and indi-viduals with a risk score >1 per 100 were recommended to use aspirin (162 mg once daily at bedtime, <16-36 weeks). Implementation metrics assessed included: acceptability, operational impact, proportion of aspirin initia-tion, quality and safety measures, and screen performance.RESULTS: Between December 1, 2020 and April 23, 2021, 1124 patients consented to preeclampsia screening (98.3% uptake), and 92 (8.2%) screened positive. Appointments for patients receiving first -trimes-ter combined screening aneuploidy and preeclampsia screening averaged 6 minutes longer than first-trimester combined screening alone, and add-ing uterine artery Doppler pulsatility index averaged 2 minutes. Of the 92 patients who screened as high-risk for preeclampsia, 72 (78.3%) were successfully contacted before 16 weeks' gestation. Of these, 62 (86.1%) initiated aspirin, and 10 (13.9%) did not. Performance audit identified a consistent negative bias with mean arterial pressure measurements (median multiple of the median <1 in 10%); other variables were satisfac-tory. There were 7 cases of preterm preeclampsia (0.69%): 5 and 2 in the high-and low-risk groups, respectively. Screening detected 5 of 7 (71.4 %) preterm preeclampsia cases, with improved performance after adjust-ment for aspirin treatment effect.CONCLUSION: This study confirms the operational feasibility of imple-menting an evidence-based preeclampsia screening and prevention program in a publicly funded Canadian setting. This will facilitate imple-mentation into clinical service and the scaling up of this program at a regional and provincial level.