Pregnancy history, coronary artery calcification and bone mineral density in menopausal women

Abstract

Objective: This study examined relationships, by pregnancy histories, between bone mineral density (BMD) and coronary artery calcification (CAC) in postmenopausal women.

Methods: Forty women identified from their medical record as having pre-eclampsia (PE) were age/parity-matched with 40 women having a normotensive pregnancy (NP). Vertebral (T4-9) BMD and CAC were assessed by quantitative computed tomography in 73 (37 with PE and 36 with NP) of the 80 women. Analyses included linear regression using generalized estimating equations.

Results: Women averaged 59 years of age and 35 years from the index pregnancy. There were no significant differences in cortical, trabecular or central BMD between groups. CAC was significantly greater in the PE group (p = 0.026). In multivariable analysis, CAC was positively associated with cortical BMD (p = 0.001) and negatively associated with central BMD (p = 0.036). There was a borderline difference in the association between CAC and central BMD by pregnancy history (interaction, p = 0.057).

Conclusions: Although CAC was greater in women with a history of PE, vertebral BMD did not differ between groups. However, both cortical and central BMD were associated with CAC. The central BMD association was marginally different by pregnancy history, suggesting perhaps differences in underlying mechanisms of soft tissue calcification.

Keywords: Cardiovascular disease; osteoporosis; osteoprotegerin; postmenopausal; pre-eclampsia.

Figure 1

Comparison of volumetric bone mineral density (vBMD; mg/cc) by pregnancy history (normotensive and preeclamptic) across three cortical (left panel), central (middle panel), and trabecular (right panel) bone regions. Data points represent the average vBMD derived from all vertebra scanned for a single study participant. Bar represents median, box represents the 25^th and 75^th percentiles, and the vertical lines represent the range. No significant differences were observed between groups for any bone region.

Figure 2

Estimated differences in BMD between NP and PE groups (Age- and BMI-Adjusted).

Figure 3

Regression analysis comparing volumetric bone mineral density (vBMD, mg/cc) from cortical (left panel), trabecular (middle panel) and central (right panel) regions of the spine with coronary artery calcification (CAC scores in log of Agatston units) in menopausal women with histories of preeclamptic, and normotensive pregnancies. Both calibrated and uncalibrated scans were included. Each data point represents the average vBMD of all captured vertebrae of a single study participant, along with their CAC score.

Figure 4

In the subset of N=39 women in whom data were available, median with 25^th and 75^th quartile range of intensity (average pixel values) for osteoprotegerin (OPG, left panel) and osteopontin (OPN, right panel) measured by customized protein array in serum from women with histories of normotensive (NP) or preeclamptic (PE) pregnancies. After adjustment for calcification (positive versus negative), there were significant differences in OPG (P=0.005) and OPN (P=0.044) levels between groups.