Aortic Calcifications Linked With Accelerated Bone Loss, Fractures

Yael Waknine

September 13, 2004

Sept. 13, 2004 — Aortic calcifications are a strong predictor for low bone density and fragility fractures of the hip and spine in postmenopausal women, according to the results of a retrospective, longitudinal study published in the September issue of the Journal of Clinical Endocrinology and Metabolism.

"Atherosclerosis and osteoporosis are polygenic, degenerative diseases common in the elderly population, and their prevalence is increasing," write Eloy Schulz, MD, from the Department of Radiology at Loma Linda University Medical Center in California, and colleagues. "Because they are common, both diseases are frequently observed in the same individual."

Although multiple reports have suggested a link between atherosclerosis and osteoporosis, making an unequivocal connection between the two conditions has been difficult, the authors point out. In this study, investigators used computed tomography (CT) to quantify the mineral in arterial and skeletal tissues with precision and accuracy, avoiding the limitations of conventional radiography and photon or x-ray absorptiometry that were used in the past.

The CTs and medical records of 2,348 healthy postmenopausal women aged 50 years and older were examined for measures of aortic calcification, values for bone mineral density (BMD), and number of fragility fractures. A subgroup of women remaining healthy (mean age, 65.2 ± 9.8 years) and having repeat CT studies at 2.1 ± 1.9 years after the initial examination constituted the longitudinal group in the study.

Of the initial cohort, 70% had osteoporosis, 30% had at least one vertebral fracture, and 9% had at least one hip fracture. After adjusting for age, increases in aortic calcification predicted 26.1% of the variance in BMD loss ( P < .001).

Aortic calcification was found to be directly related to the number of fractures. Women with aortic calcification were an estimated 4.8 times more likely to sustain a vertebral fracture compared with women having no calcification (95% confidence interval [CI], 3.6 - 6.5).

Women with aortic calcification were 2.9 times more likely to sustain a fracture of the proximal femur (95% CI, 1.8 - 4.8), and they experienced a higher rate of bilateral fractures (19.8% vs. 14.3%; P = .04) compared with women who did not have calcification.

Results within the longitudinal cohort were similar: the annual increase in calcification accounted for 47% of the variance in the rate of bone loss ( P < .001). Within quartiles based on the percentage annual change for calcification, calcification progression and bone loss were strongly associated. Women in the highest calcification rate quartile had significantly higher bone loss than did those of similar age in the lowest quartile (5.3% vs. 1.3% annually; P < .001).

"The findings of this study, showing that beyond the aging process there is a significant relation between atherosclerosis and osteoporosis, should encourage research on the mechanisms regulating mineral deposition in connective tissues...[and] effective prevention and treatment strategies that may simultaneously modify the risk for these two common conditions," the authors note, adding that the connection between calcified plaques and bone loss in young postmenopausal women should aid in early identification of those at risk for osteoporosis and fractures.

The study was supported in part by grants from the National Institutes of Health and the Department of the Army.

In an accompanying editorial, Mishaela R. Rubin, MD, and Shonni J. Silverberg, MD, from Columbia University in New York City, write, "The use of CT technology for both aortic and spine measurements in this study makes it an important addition to the existing literature."

Suggesting further investigation of the association in men and women with a larger BMD spectrum, and the use of larger, prospective studies with a standardized interscan time to confirm the current longitudinal results, Drs. Rubin and Silverberg conclude, "Such clinical observations will complement the growing body of data emerging from the laboratory on the intersection of vascular calcification and bone biology."

J Clin Endocrinol Metab. 2004;89:4243-4245, 4246-4253

Reviewed by Gary D. Vogin, MD