title: Vitamin D insufficiency over 5 years is associated with increased fracture risk-an observational cohort study of elderly women.
abstract: This study of elderly Swedish women investigated the association between chronic vitamin D insufficiency and osteoporotic fractures occurring between ages 80-90. The incidence and risk of hip and major osteoporotic fractures was significantly higher in elderly women with low vitamin D levels maintained over 5 years.
  
  
  BACKGROUND
  Vitamin D insufficiency among the elderly is common; however, relatively little is known about the effects of long-term hypovitaminosis D on fracture. We investigated sequential assessment of serum 25(OH)D at age 75 and 80 to determine if continuously low 25(OH)D levels are associated with increased 10-year fracture incidence.
  
  
  METHODS
  One thousand forty-four Swedish women from the population-based OPRA cohort, all 75 years old, attended at baseline (BL); 715 attended at 5 years. S-25(OH)D was available in 987 and 640, respectively and categorized as: <50 (Low), 50-75 (Intermediate), and >75 nmol/L (High). Incident fracture data was collected with maximum follow-up to 90 years of age.
  
  
  RESULTS
  Hip fracture incidence between age 80-85 was higher in women who had low 25(OH)D at both baseline and 5 years (22.2 % (Low) vs. 6.6 % (High); p = 0.003). Between age 80-90, hip fracture incidence was more than double that of women in the high category (27.9 vs. 12.3 %; p = 0.006). Within 5-years, 50 % of women in the continuously low group compared to 34 % in the continuously high 25(OH)D group had an osteoporotic fracture (p = 0.004) while 10-year incidence was higher compared to the intermediate (p = 0.020) but not the high category (p = 0.053). The 10-year relative risk of hip fracture was almost three times higher and osteoporotic fracture risk almost doubled for women in the lowest 25(OH)D category compared to the high category (HR 2.7 and 1.7; p = 0.003 and 0.023, respectively).
  
  
  CONCLUSIONS
  In these elderly women, 25(OH)D insufficiency over 5-years was associated with increased 10-year risk of hip and major osteoporotic fractures.
authors.affiliation: Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Science Malmö, Lund University, Lund, Sweden, david.buchebner@med.lu.se.
authors.forename: D
authors.initials: D
authors.lastname: Buchebner
authors.forename: F
authors.initials: F
authors.lastname: McGuigan
authors.forename: P
authors.initials: P
authors.lastname: Gerdhem
authors.forename: J
authors.initials: J
authors.lastname: Malm
authors.forename: M
authors.initials: M
authors.lastname: Ridderstråle
authors.forename: K
authors.initials: K
authors.lastname: Akesson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006620:Hip Fractures / Q000097:blood / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D015994:Incidence; D058866:Osteoporotic Fractures / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D018570:Risk Assessment / Q000379:methods; D013548:Sweden / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D