Obstetrics
Can antenatal clinical and biochemical markers predict the development of severe preeclampsia?*

https://doi.org/10.1067/mob.2000.103890Get rights and content

Abstract

Objective: This study was undertaken to develop a multivariable clinical predictive rule for severe preeclampsia using second-trimester clinical factors and biochemical markers. Study Design: We performed a retrospective cohort study of all pregnant patients with single gestations from 1995 through 1997 for whom we had complete follow-up data. Through medical record review we determined whether patients had severe preeclampsia develop according to American College of Obstetricians and Gynecologists criteria. Case patients with severe preeclampsia were compared with control subjects with respect to clinical data and multiple-marker screening test results. With potential predictive factors identified in the bivariate and stratified analyses both an explanatory logistic regression model and a clinical prediction rule were created. Patients were assigned a predictive score according to the presence or absence of predictive factors, and receiver operating characteristic analysis was used to determine the optimal score cutoff point for prediction of severe preeclampsia with maximal sensitivity. Results: Among the 1998 patients we found 49 patients with severe preeclampsia (prevalence, 2.5%). After we controlled for confounding variables, case patients and control subjects had similar human chorionic gonadotropin and α-fetoprotein levels, and the only variables that remained significantly associated with severe preeclampsia were nulliparity (relative risk, 3.8; 95% confidence interval, 1.7-8.3), history of preeclampsia (relative risk, 5.0; 95% confidence interval, 1.7-17.2), elevated screening mean arterial pressure (relative risk, 3.5; 95% confidence interval, 1.7-7.2), and low unconjugated estriol concentration (relative risk, 1.7; 95% confidence interval, 0.9-3.4). Our predictive model for severe preeclampsia, which included only these 4 variables, had a sensitivity of 76% and a specificity of 46%. Conclusion: Even after incorporation of the strongest risk factors, our predictive model had only modest sensitivity and specificity for discrimination of patients at risk for development of severe preeclampsia. The addition of the human chorionic gonadotropin and α-fetoprotein biochemical markers did not enhance the model’s predictive value for severe preeclampsia. (Am J Obstet Gynecol 2000;182:589-94.)

Section snippets

Material and methods

To develop a clinical prediction rule to discriminate patients at highest risk for severe preeclampsia we performed a retrospective cohort study of all pregnant patients with singleton gestations from 1995 through 1997 who underwent second-trimester multiple-marker screening, also known as the triple screen. Patient records were selected from a database of multiple-marker screening test results. In all cases serum screening was performed between 15 and 20 weeks’ gestation. Serum screening

Results

Among the 1998 patients we found 128 cases of preeclampsia (prevalence, 6.4%) and 49 cases of severe preeclampsia (prevalence, 2.5%). In the bivariate analysis case patients with severe preeclampsia were more likely to be nulliparous; to have a history of preeclampsia, autoimmune diseases, and chronic hypertension; to have an elevated (>90 mm Hg) screening MAP and third-trimester MAP; and to have a low second-trimester unconjugated estriol concentration (<0.9 MoM; Tables I and II).

. Unadjusted

Comment

Being able to predict which patients are at greatest risk for development of severe preeclampsia would be of great value in preventive and interventional studies because it would be possible to discriminate a high-risk population that could benefit from more aggressive treatment and intense observation. With this in mind, we sought to develop a clinical prediction model for severe preeclampsia through a retrospective cohort study. We chose to focus on prediction of severe preeclampsia because

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    *

    Reprint requests: David M. Stamilio, MD, USAF David Grant Medical Center, Department of Obstetrics and Gynecology, 101 Bodin Cir, Travis AFB, CA 94535-1800.

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