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How to calculate the risk of preeclampsia in women with a history of positive screening

Published:April 19, 2020DOI:https://doi.org/10.1016/j.ajog.2020.04.007
      To the Editors:
      With the current demonstration of the benefits of aspirin initiated in early pregnancy to prevent the most severe and preterm forms of preeclampsia, there is a growing interest for the prediction of preterm preeclampsia in the first trimester of pregnancy.
      • Roberge S.
      • Bujold E.
      • Nicolaides K.H.
      Aspirin for the prevention of preterm and term preeclampsia: systematic review and metaanalysis.
      In the review by Wright et al,
      • Wright D.
      • Wright A.
      • Nicolaides K.H.
      The competing risk approach for prediction of preeclampsia.
      the authors reported that approximately 90% of women who will develop early preeclampsia could be identified using a competing risks approach in the first trimester of pregnancy, with a false-positive rate of 10%. The screening rate for preterm preeclampsia was approximately 70% for nulliparous women and 65% for white nulliparous women.
      • O’Gorman N.
      • Wright D.
      • Syngelaki A.
      • et al.
      Competing risks model in screening for preeclampsia by maternal factors and biomarkers at 11–13 weeks gestation.
      Aspirin initiated before 16 weeks’ gestation at a daily dose of >100 mg and with good compliance substantially reduces the overall risk of preeclampsia and more specifically the risk of preterm preeclampsia.
      • Roberge S.
      • Bujold E.
      • Nicolaides K.H.
      Aspirin for the prevention of preterm and term preeclampsia: systematic review and metaanalysis.
      This strategy of combining the prediction and prevention of preeclampsia is likely to become standard practice in reducing the overall rate of early preeclampsia in several centers and countries.
      In the current algorithm, an important factor influencing the risk of preeclampsia in parous women is a history of preeclampsia, and particularly, a history of preterm preeclampsia (relative risk for preterm preeclampsia from 6 to 30 times). However, we wondered how to manage (or to include in the algorithm) women who had a positive screening result in their previous pregnancy, who took aspirin accordingly, and who did not develop preterm preeclampsia.
      We are aware that aspirin seems to delay the development of preeclampsia,
      • Wright D.
      • Nicolaides K.H.
      Aspirin delays the development of preeclampsia.
      and consequently some women will instead develop a term preeclampsia; however, a history of term preeclampsia is a much lower risk factor than a history of preterm preeclampsia in the algorithm. Given the positive screening rate of approximately 11.3%
      • O’Gorman N.
      • Wright D.
      • Syngelaki A.
      • et al.
      Competing risks model in screening for preeclampsia by maternal factors and biomarkers at 11–13 weeks gestation.
      and the substantial weightage of previous pregnancy history in the risk calculation of preeclampsia, it is necessary to propose a specific screening strategy for pregnant women with a positive screening history. Some options seem possible, and we would like to know the opinion of the authors.
      With the increasing number of women with a positive screening result at their first pregnancies, knowledge in this area will improve, and the algorithm will eventually include this criterion. For the time being, considering that most women with a positive screening result and treated with aspirin do not develop preeclampsia, will physicians run the risk of not treating them during their subsequent pregnancies? Would these women not prefer to take aspirin because taking aspirin had potentially prevented adverse pregnancy outcomes?

      References

        • Roberge S.
        • Bujold E.
        • Nicolaides K.H.
        Aspirin for the prevention of preterm and term preeclampsia: systematic review and metaanalysis.
        Am J Obstet Gynecol. 2018; 218: 287-293.e1
        • Wright D.
        • Wright A.
        • Nicolaides K.H.
        The competing risk approach for prediction of preeclampsia.
        Am J Obstet Gynecol. 2019; ([Epub ahead of print])
        • O’Gorman N.
        • Wright D.
        • Syngelaki A.
        • et al.
        Competing risks model in screening for preeclampsia by maternal factors and biomarkers at 11–13 weeks gestation.
        Am J Obstet Gynecol. 2016; 214: 103.e1-103.e12
        • Wright D.
        • Nicolaides K.H.
        Aspirin delays the development of preeclampsia.
        Am J Obstet Gynecol. 2019; 220: 580.e1-580.e6

      Linked Article

      • The competing risk approach for prediction of preeclampsia
        American Journal of Obstetrics & GynecologyVol. 223Issue 1
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          The established method of the assessment of the risk for development of preeclampsia is to identify risk factors from maternal demographic characteristics and medical history; in the presence of such factors, the patient is classified as high risk and in their absence as low risk. Although this approach is simple to perform, it has poor performance of the prediction of preeclampsia and does not provide patient-specific risks. This review describes a new approach that allows the estimation of patient-specific risks of delivery with preeclampsia before any specified gestational age by maternal demographic characteristics and medical history with biomarkers obtained either individually or in combination at any stage in pregnancy.
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      • Competing risks model for prediction of preeclampsia
        American Journal of Obstetrics & GynecologyVol. 225Issue 2
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          We are grateful to Drs Guerby and Bujold for raising an important question.1 The competing risks model uses data on maternal demographic characteristics and medical history along with biomarker measurements to produce risks of delivery with preeclampsia (PE) before any specified gestational age.2 Compared with the risk of PE in nulliparous pregnant women, the risk is substantially increased in parous women with history of PE in their previous pregnancy and the risk is decreased in parous women with no history of PE.
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