Alexander R Opotowsky1, John P Bilezikian. 1. Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
Abstract
BACKGROUND: Recent studies on the association between vitamin A and fracture risk have focused on samples with high vitamin A intake. We analyzed a cohort that was more representative of the overall U.S. population to test the hypothesis that both high and low serum vitamin A concentrations increase the risk of hip fracture. METHODS: We utilized data on 2799 women who were 50 to 74 years of age from the first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. There were 172 incident hip fractures during the 22-year follow-up period. Using Cox regression analysis, we analyzed the relation between baseline serum vitamin A (retinol and retinyl esters) concentration, as a continuous variable and by quintiles, and hip fracture risk. RESULTS: While there was no linear relation between serum vitamin A concentration and the risk of hip fracture in the multivariate analysis (hazard ratio [HR] per SD increase = 1.0; 95% confidence interval [CI]: 0.9 to 1.2), analysis by quintiles revealed a U-shaped relation between serum vitamin A concentration and hip fracture. Fracture risk was significantly higher among subjects in the lowest (HR = 1.9; 95% CI: 1.1 to 3.3) and highest (HR = 2.1; 95% CI: 1.2 to 3.6) quintiles compared with those in the middle quintiles. CONCLUSION: Both low and high serum vitamin A concentrations may be associated with an increased risk of hip fracture.
BACKGROUND: Recent studies on the association between vitamin A and fracture risk have focused on samples with high vitamin A intake. We analyzed a cohort that was more representative of the overall U.S. population to test the hypothesis that both high and low serum vitamin A concentrations increase the risk of hip fracture. METHODS: We utilized data on 2799 women who were 50 to 74 years of age from the first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. There were 172 incident hip fractures during the 22-year follow-up period. Using Cox regression analysis, we analyzed the relation between baseline serum vitamin A (retinol and retinyl esters) concentration, as a continuous variable and by quintiles, and hip fracture risk. RESULTS: While there was no linear relation between serum vitamin A concentration and the risk of hip fracture in the multivariate analysis (hazard ratio [HR] per SD increase = 1.0; 95% confidence interval [CI]: 0.9 to 1.2), analysis by quintiles revealed a U-shaped relation between serum vitamin A concentration and hip fracture. Fracture risk was significantly higher among subjects in the lowest (HR = 1.9; 95% CI: 1.1 to 3.3) and highest (HR = 2.1; 95% CI: 1.2 to 3.6) quintiles compared with those in the middle quintiles. CONCLUSION: Both low and high serum vitamin A concentrations may be associated with an increased risk of hip fracture.
Authors: G L Ambrosini; A P Bremner; A Reid; D Mackerras; H Alfonso; N J Olsen; A W Musk; N H de Klerk Journal: Osteoporos Int Date: 2012-09-18 Impact factor: 4.507
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