Abstract P001: Atrial Fibrillation and the Risk of Osteoporotic Fracture in the Cardiovascular Health Study
Background: Atrial fibrillation (AF) is common in older adults and is associated with an increased risk of stroke, heart failure, dementia, and death. Prior studies have observed that individuals with stroke and heart failure are at higher risk of sustaining a hip or other osteoporotic fracture, but whether individuals with AF are at higher risk of fracture is unknown. AF is associated with dizziness, weakness, and decreased cardiac and cerebral perfusion, and these in turn may increase the likelihood of falls. Oral anticoagulants, used to prevent stroke in AF, have also been linked to reduced bone mineral density. We examined the associations of incident AF with the risk of hip and other osteoporotic fractures using data from the Cardiovascular Health Study (CHS), a prospective cohort study of older adults.
Hypothesis: We hypothesized that individuals with incident AF would be at higher risk of osteoporotic fracture compared with those without AF.
Methods: The study population included 4481 CHS participants aged 65 years and older and enrolled in fee-for-service Medicare followed between 1991 and 2009. Individuals with prevalent AF or a history of stroke or heart failure at baseline were excluded. Incident AF was identified by annual study ECG, hospital discharge diagnosis ascertained during cohort follow-up, or AF diagnosis in Medicare inpatient, outpatient, or physician service claims. Osteoporotic fracture, defined as fracture of the hip, distal forearm, humerus, or pelvis, was also identified using hospital discharge diagnosis or Medicare claims. Once an AF diagnosis was made, participants were classified thereafter as having AF. We used Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between AF, modeled as a time-varying exposure, and the risk of osteoporotic fracture, adjusting for baseline age, sex, race, clinic, education, smoking, alcohol use, physical activity, body mass index, diabetes, anti-hypertensive drug use, and coronary heart disease. We also evaluated effect modification by sex and oral anticoagulant use with Wald tests.
Results: Mean age at baseline was 72 years; 41% were men, and 86% were white. Over a mean follow-up of 9.0 years, 1424 individuals (32%) developed AF and 719 (16%) sustained a fracture, 430 at the hip. Individuals with incident AF were not shown to be at higher risk of osteoporotic fracture (adjusted HR=1.00, 95% CI 0.80-1.24) or hip fracture (adjusted HR=1.13, 95% CI 0.87-1.47) compared with those without AF. There was no evidence of interaction by gender or oral anticoagulant use for either hip or osteoporotic fracture (p>0.05 for all).
Conclusion: Although osteoporotic fractures and atrial fibrillation are both significant health problems in the elderly, the results of this study suggest that incident AF is not a risk factor for osteoporotic fracture in community-dwelling older adults.
- © 2013 by American Heart Association, Inc.