Using the algorithm of the Fetal Medicine Foundation to determine the cutoff point for prediction of pre-eclampsia in a Brazilian population.

Background: To use the algorithm of the Fetal Medicine Foundation (FMF) to determine the cutoff point for prediction of preeclampsia (PE) in a Brazilian population.

Methods: Randomized clinical trial with 274 nulliparous patients at gestational age between 11 and 13 weeks and 6 days. To calculate the risk of PE, the algorithm available at the website of the FMF (http://fetalmedicine.org/research/assess/preeclampsia/first-trimester) was used. Among the patients, 138 did not use preventive measures (100 mg/day aspirin [ASA]). Youden's criteria were used to calculate the cutoff point. To test the effectiveness of 100 mg/day ASA in preventing PE, the patients were divided into two groups - at risk above and below the cutoff point.

Results: In the group comprising the 135 patients that did not take ASA, the median age was 22 years, the Body Mass Index (BMI) was 59.3 kg/m, the mean arterial pressure (MAP) was 73.3 mmHg, and the mean pulsatility index of uterine artery Doppler was 1.71. The median gestational age at delivery was 39.3 (38.1-40.3) weeks. The prevalence of PE was 11.1%. In our sample, the use of 100 mg/day ASA reduced total PE by 36.3% (prevalence of PE in the group above the cutoff point was 19% and 12.1% when ASA and placebo were used, respectively).

Conclusions: The cutoff point defined for prediction of PE was 1:155 with sensitivity of 80%, specificity of 57.5%, positive predictive value of 19.1%, and negative predictive value of 95%, which should help to select patients that will benefit from prophylactic ASA.