Age-Related Factors Associated with Hip Fracture Risk.

OBJECTIVES: Advancing age is a powerful risk factor for hip fracture. The biological mechanisms through which aging impacts hip fracture risk have not been well studied.

METHODS: Biological factors associated with "advancing age" that help to explain how aging is associated with hip fracture risk are reviewed. The findings are based on analyses of the Cardiovascular Health Study, an ongoing observational study of adults ages >65 years with 25 years of follow up.

RESULTS: Five age-related factors were found to be significantly associated with hip fracture risk: (1) microvascular disease of the kidney (albuminuria and / or elevated urine albumin to creatinine ratio) and of the brain (abnormal white matter disease on brain MRI); (2) increased serum levels of carboxymethyl-lysine (CML), an advanced glycation end-product that reflects glycation and oxidative stress; (3) reduced parasympathetic tone, as derived from 24-hour Holter monitoring; (4) carotid artery atherosclerosis in the absence of clinical cardiovascular disease; and (5) increased trans-fatty acid levels in the blood. Each of these factors was associated with a 10-25%. increased risk of fracture. These associations were independent of traditional risk factors for hip fracture.

CONCLUSION: Several factors associated with older age help to explain how "aging" may be associated with hip fracture risk. These same factors may also explain the high risk for mortality following hip fracture.