A combination of low serum concentrations of vitamins K1 and D is associated with increased risk of hip fractures in elderly Norwegians: a NOREPOS study
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The present study investigated the risk of incident hip fractures according to serum concentrations of vitamin K1 and 25-hydroxyvitamin D in elderly Norwegians during long-term follow-up. The results showed that the combination of low concentrations of both vitamin D and K1 provides a significant risk factor for hip fractures.
This case-cohort study aims to investigate the associations between serum vitamin K1 and hip fracture and the possible effect of 25-hydroxyvitamin D (25(OH)D) on this association.
The source cohort was 21,774 men and women aged 65 to 79 years who attended Norwegian community-based health studies during 1994–2001. Hip fractures were identified through hospital registers during median follow-up of 8.2 years. Vitamins were determined in serum obtained at baseline in all hip fracture cases (n = 1090) and in a randomly selected subcohort (n = 1318). Cox proportional hazards regression with quartiles of serum vitamin K1 as explanatory variable was performed. Analyses were further performed with the following four groups as explanatory variable: I: vitamin K1 ≥ 0.76 and 25(OH)D ≥ 50 nmol/l, II: vitamin K1 ≥ 0.76 and 25(OH)D < 50 nmol/l, III: vitamin K1 < 0.76 and 25(OH)D ≥ 50 nmol/l, and IV: vitamin K1 < 0.76 and 25(OH)D < 50 nmol/l.
Age- and sex-adjusted analyses revealed an inverse association between quartiles of vitamin K1 and the risk of hip fracture. Further, a 50 % higher risk of hip fracture was observed in subjects with both low vitamin K1 and 25(OH)D compared with subjects with high vitamin K1 and 25(OH)D (HR 1.50, 95 % CI 1.18–1.90). The association remained statistically significant after adjusting for body mass index, smoking, triglycerides, and serum α-tocopherol. No increased risk was observed in the groups low in one vitamin only.
Combination of low concentrations of vitamin K1 and 25(OH)D is associated with increased risk of hip fractures.
KeywordsCase cohort Elderly Hip fracture Osteoporosis Vitamin D Vitamin K1
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Conflicts of interest
Trine Elisabeth Finnes, Cathrine Marie Lofthus, Haakon Eduard Meyer, Anne Johanne Søgaard, Grethe S. Tell, Ellen Margrethe Apalset, Clara Gjesdal, Guri Grimnes, Berit Schei, Sven Ove Samuelsen, and Kristin Holvik declare that they have no conflict of interest. Rune Blomhoff has an interest (ownership) in the chemical analysis company Vitas AS (established by the Oslo Innovation Centre)
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