Cardiovascular risk estimation in women with a history of hypertensive pregnancy disorders at term: a longitudinal follow-up study

Abstract

Background: Cardiovascular disease is associated with major morbidity and mortality in women in the Western world. Prediction of an individual cardiovascular disease risk in young women is difficult. It is known that women with hypertensive pregnancy complications have an increased risk for developing cardiovascular disease in later life and pregnancy might be used as a cardiovascular stress test to identify women who are at high risk for cardiovascular disease. In this study we assess the possibility of long term cardiovascular risk prediction in women with a history of hypertensive pregnancy disorders at term.

Methods: In a longitudinal follow-up study, between June 2008 and November 2010, 300 women with a history of hypertensive pregnancy disorders at term (HTP cohort) and 94 women with a history of normotensive pregnancies at term (NTP cohort) were included. From the cardiovascular risk status that was known two years after index pregnancy we calculated individual (extrapolated) 10-and 30-year cardiovascular event risks using four different risk prediction models including the Framingham risk score, the SCORE score and the Reynolds risk score. Continuous data were analyzed using the Student's T test and Mann-Whitney U test and categorical data by the Chi-squared test. A poisson regression analysis was performed to calculate the incidence risk ratios and corresponding 95% confidence intervals for the different cardiovascular risk estimation categories.

Results: After a mean follow-up of 2.5 years, HTP women had significantly higher mean (SD) extrapolated 10-year cardiovascular event risks (HTP 7.2% (3.7); NTP 4.4% (1.9) (p<.001, IRR 5.8, 95% CI 1.9 to 19)) and 30-year cardiovascular event risks (HTP 11% (7.6); NTP 7.3% (3.5) (p<.001, IRR 2.7, 95% CI 1.6 to 4.5)) as compared to NTP women calculated by the Framingham risk scores. The SCORE score and the Reynolds risk score showed similar significant results.

Conclusions: Women with a history of gestational hypertension or preeclampsia at term have higher predicted (extrapolated) 10-year and 30-year cardiovascular event risks as compared to women with a history of uncomplicated pregnancies. Further large prospective studies have to evaluate whether hypertensive pregnancy disorders have to be included as an independent variable in cardiovascular risk prediction models for women.

Figure 1

10 - Year Framingham risk scores (%) of women with a history of gestational hypertension or preeclampsia at term (HTTP women closed bars) and women with a history of uncomplicated normotensive pregnancies (NTP women, dotted bars). The top and bottom of each box correspond to the 75th percentile and 25th percentile, respectively. The whiskers (t bars) on the top and botttom denote the 90th percentile and 10th percentile, respectively.

Figure 2

10-year Framingham risk score extrapolated to the age of 60 years. A. 10-Year Framingham risk scores (%) extrapolated to the age of 60 years of women with a history of uncomplicated normotensive pregnancies (NTP women, dotted bars). The top and bottom of each box correspond to the 75th percentile and 25th percentile, respectively. The whiskers (t bars) on the top and botttom denote the 90th percentile and 10th percentile, respectively. B. Division into 4 different risk categories (0 - 5%, >5% - 10%>10% - 20% and >20%). 10-Year risk of estimation of overall cardiovascular disease risk according to the Framingham Heart Study algorithm based on the following risk factors, ie. age, smoking, systolic blood pressure, HDL cholesterol, total cholesterol.

Figure 3

30-year Framingham risk score at current age. A. 30 - Year Framingham risk scores (%) at current age of women with a history of gestational hypertension or preeclampsia at term (HTTP women closed bars) and women with a history of uncomplicated normotensive pregnancies (NTP women, dotted bars). The top and bottom of each box correspond to the 75th percentile and 25th percentile, respectively. The whiskers (t bars) on the top and botttom denote the 90th percentile and 10th percentile, respectively. B. Division into 4 different risk categories (0 - 5%, >5% - 10%>10% - 20% and >20%). 30 - year risk of estimation of full cardiovascular disease risk by the Framingham Heart Study algorithm based on the following risk factors, ie. age, smoking, systolic blood pressure, HDL cholesterol, total cholesterol, treatment for hypertension and presence of diabetes.