Bone mineral density and the risk of peripheral arterial disease: the Rotterdam Study

Low estrogen exposure throughout life is thought to result in low bone mineral density (BMD) and an increased incidence of cardiovascular disease. In the Rotterdam Study we cross-sectionally examined the relation between BMD and peripheral arterial disease (PAD), as assessed by an ankle-arm index (AAI) of <0.9 in either leg. Data on BMD and PAD were available for 5268 individuals (3053 women, 2215 men). From the BMD, Z-scores were calculated and subsequently divided into tertiles. Logistic regression analysis was used to compute odds ratios (OR) for PAD in tertiles of BMD, using the upper tertile as a reference. When adjusting for age, women with a low femoral neck BMD had a significantly increased risk of PAD (OR = 1.49, 95% CI 1.16-1.91). This could not be found for men (1.14, 0.84-1.53). The mid-tertile did not differ from the reference in either men or women. In women, additional adjustment for several potential confounders resulted in a somewhat lowered risk estimate (1.35, 1.02-1.79). In contrast, no association between lumbar spine BMD and PAD could be observed in either men or women. Our study shows an association between low femoral neck BMD and PAD in women only, an association unlikely to be causal. Estrogen deficiency may be the common denominator in osteoporosis and PAD, resulting in clustering of these two major diseases in postmenopausal women.