First trimester serum angiogenic and anti-angiogenic factors in women with chronic hypertension for the prediction of preeclampsia

BACKGROUND: An imbalance between angiogenic and antiangiogenic factors is thought to be a central pathogenetic mechanism in preeclampsia. In pregnancies that subsequently experience preeclampsia, the maternal serum concentration of the angiogenic placental growth factor is decreased from as early as the first trimester of pregnancy, and the concentration of the antiangiogenic soluble fms-like tyrosine kinase-1 is increased in the last few weeks before the clinical presentation of the disease. Chronic hypertension, which complicates 1-2% of pregnancies, is the highest risk factor for the development of preeclampsia among all other factors in maternal demographic characteristics and medical history. Two previous studies in women with chronic hypertension reported that first-trimester serum placental growth factor and soluble fms-like tyrosine kinase-1 levels were not significantly different between those who experienced superimposed preeclampsia and those who did not, whereas a third study reported that concentrations of placental growth factor were decreased. OBJECTIVE: The purpose of this study was to investigate whether, in women with chronic hypertension, serum concentrations of placental growth factor and soluble fms-like tyrosine kinase-1 and soluble fms-like tyrosine kinase-1/placental growth factor ratio at 11(+0) -13(+6) weeks gestation are different between those women who experienced superimposed preeclampsia and those who did not and to compare these values with those in normotensive control subjects. STUDY DESIGN: The study population comprised 650 women with chronic hypertension, which included 202 women who experienced superimposed preeclampsia and 448 women who did not experience preeclampsia, and 142 normotensive control subjects. Maternal serum concentration of placental growth factor and soluble fms-like tyrosine kinase-1 were measured by an automated biochemical analyzer and converted into multiples of the expected median with the use of multivariate regression analysis in the control group. Comparisons of placental growth factor and soluble fms-like tyrosine kinase-1 levels and soluble fms-like tyrosine kinase-1/placental growth factor ratio in multiples of the expected median values between the 2 groups of chronic hypertension and the control subjects were made with the analysis of variance or the Kruskal-Wallis test. RESULTS: In the group of women with chronic hypertension who experienced preeclampsia compared with those women who did not experience preeclampsia, there were significantly lower median concentrations of serum placental growth factor multiples of the expected median (0.904 [interquartile range, 0.771-1.052] vs 0.948 [interquartile range, 0.814-1.093]; P=.014) and soluble fms-like tyrosine kinase-1 multiples of the expected median (0.895 [interquartile range, 0.760-1.033] vs 0.938 [interquartile range, 0.807-1.095]; P=.013); they were both lower than in the normotensive control subjects (1.009 [interquartile range, 0.901-1.111] and 0.991 [interquartile range, 0.861-1.159], respectively; P<.01 for both). There were no significant differences among the 3 groups in soluble fms-like tyrosine kinase-1/placental growth factor ratios. In women with chronic hypertension, serum placental growth factor and soluble fms-like tyrosine kinase-1 levels provided poor prediction of superimposed preeclampsia (area under the curve, 0.567 [95% confidence interval, 0.537-0.615] and 0.546 [95% confidence interval, 0.507-0.585], respectively). CONCLUSION: Women with chronic hypertension, and particularly those who subsequently experienced preeclampsia, have reduced first-trimester concentrations of both placental growth factor and soluble fms-like tyrosine kinase-1.