Background: High blood pressure is associated with abnormalities in calcium metabolism. Sustained calcium loss may lead to increased bone-mineral loss in people with high blood pressure. We investigated the prospective association between blood pressure and bone-mineral loss over time in elderly white women.
Methods: We studied 3676 women who were initially assessed in 1988-90 (mean age 73 years [SD 4, range 66-91 years]; mean bodyweight 65.3 kg [11.5]; blood pressure 137/75 mm Hg [17/9]) who were not on thiazide diuretics. Mean follow-up was 3.5 years. Anthropometry, blood pressure, and bone-mineral density at the femoral neck were measured at baseline and bone densitometry was repeated after 3.5 years by dual-energy X-ray absorptiometry.
Findings: After adjustment for age, initial bone-mineral density, weight and weight change, smoking, and regular use of hormone-replacement therapy, the rate of bone loss at the femoral neck increased with blood pressure at baseline. In the quartiles of systolic blood pressure, yearly bone losses increased from 2.26 mg/cm2 (95% CI 1.48-3.04) in the first quartile to 3.79 mg/cm2 in the fourth quartile (3.13-4.45; test for heterogeneity, p=0.03; test for linear trend, p=0.01), equivalent to yearly changes of 0.34% (0.20-0.46) and 0.59% (0.49-0.69; test for heterogeneity, p=0.02; test for linear trend, p=0.005). There was no significant interaction with age. The exclusion of women on antihypertensive drugs did not alter the results. For diastolic blood pressure, there was an association with bone loss in women younger than 75 years.
Interpretation: Higher blood pressure in elderly white women is associated with increased bone loss at the femoral neck. This association may reflect greater calcium losses associated with high blood pressure, which may contribute to the risk of hip fractures.