Quality assessment of first-trimester screening for preterm pre-eclampsia

Objective To assess the performance and impact of first-trimester preterm pre-eclampsia screening in a single center.Methods This was a single-center study of women with a singleton pregnancy who were screened prospectively for preterm pre-eclampsia (i.e. delivery before 37 weeks' gestation) using maternal characteristics, mean arterial pressure (MAP), uterine artery Doppler pulsatility index, maternal serum pregnancy-associated plasma protein-A and placental growth factor. The individual risk for preterm pre-eclampsia was estimated from a published model, and those with a risk above 1 in 200 were recommended to take 150 mg soluble aspirin per day until 34 weeks. Information on the incidence of pre-eclampsia was obtained from the hospital register of adverse pregnancy outcomes. Screening performance indicators, including detection and false-positive rates, were estimated from the distribution of risks. Screening impact was estimated by dividing the observed prevalence by the expected prevalence, which was derived from the distribution of risks.Results The distributions of MAP, uterine artery Doppler pulsatility index and serum markers were consistent with the risk model parameters. The estimated detection and false-positive rates were 79.7% and 16.2%, respectively. There were six cases of preterm pre-eclampsia, four of which occurred in women with a positive screening result. The prevalence was 62% of that expected, but the 95% CI of 23-140% indicated that the study was underpowered to assess the impact.Conclusions This study demonstrates that the performance of preterm pre-eclampsia screening can be estimated in a single center with fewer than 2000 women screened. However, in order to assess the impact of screening on the prevalence of the condition, a much larger cohort is needed.