title: Effect of vitamin D on bone mineral density of elderly patients with osteoporosis responding poorly to bisphosphonates.
abstract: BACKGROUND
  Bisphosphonates are indicated in the prevention and treatment of osteoporosis. However, bone mineral density (BMD) continues to decline in up to 15% of bisphosphonate users. While randomized trials have evaluated the efficacy of concurrent bisphosphonates and vitamin D, the incremental benefit of vitamin D remains uncertain.
  
  
  METHODS
  Using data from the Canadian Database of Osteoporosis and Osteopenia (CANDOO), we performed a 2-year observational cohort study. At baseline, all patients were prescribed a bisphosphonate and counseled on vitamin D supplementation. After one year, patients were divided into two groups based on their response to bisphosphonate treatment. Non-responders were prescribed vitamin D 1000 IU daily. Responders continued to receive counseling on vitamin D.
  
  
  RESULTS
  Of 449 patients identified, 159 were non-responders to bisphosphonates. 94% of patients were women. The mean age of the entire cohort was 74.6 years (standard deviation = 5.6 years). In the cohort of non-responders, BMD at the lumbar spine increased 2.19% (p < 0.001) the year after vitamin D was prescribed compared to a decrease of 0.55% (p = 0.36) the year before. In the cohort of responders, lumbar spine BMD improved 1.45% (p = 0.014) the first year and 1.11% (p = 0.60) the second year. The difference between the two groups was statistically significant the first year (p < 0.001) but not the second (p = 0.60). Similar results were observed at the femoral neck but were not statistically significant.
  
  
  CONCLUSIONS
  In elderly patients with osteoporosis not responding to bisphosphonates, vitamin D 1000 IU daily may improve BMD at the lumbar spine.
authors.affiliation: Department of Medicine, Hamilton Health Sciences, Hamilton, Ontario, Canada. heck0@rogers.com
authors.forename: George A
authors.initials: GA
authors.lastname: Heckman
authors.forename: Alexandra
authors.initials: A
authors.lastname: Papaioannou
authors.forename: Rolf J
authors.initials: RJ
authors.lastname: Sebaldt
authors.forename: George
authors.initials: G
authors.lastname: Ioannidis
authors.forename: Annie
authors.initials: A
authors.lastname: Petrie
authors.forename: Charlie
authors.initials: C
authors.lastname: Goldsmith
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Adachi