[Low] Vitamin D Concentration Linked to Hip Fracture Risk
Medpage, Aug 18

In postmenopausal women, low serum vitamin D concentrations were associated
with an increased risk for hip fracture in a nested case-control study here.

Women with the lowest serum concentrations of 25-hydroxyvitamin D were 71%
more likely to have a hip fracture than those with the highest (OR 1.71, 95%
CI 1.05 to 2.79), Jane Cauley, Dr.P.H., of the University of Pittsburgh, and
colleagues, reported in the Aug. 19 issue of Annals of Internal Medicine.

Adjusting for C-terminal telopeptide of type I collagen -- a marker for bone
resorption -- seemed to eliminate the association (OR 1.58, 95% CI 0.97 to
2.60), the researchers said, but the overall trend remained significant in a
multivariate model (P=0.029).

"Our findings suggest that low serum 25-hydroxyvitamin D concentrations
might help identify women at high risk for hip fracture," they said.

Past studies examining the link between serum vitamin D concentrations and
risk of fracture have yielded mixed results, they said.

To explore the issue, the researchers turned to the Women's Health
Initiative Observational Study, a large prospective cohort study of
participants ages 50 to 79.

They selected 400 women who had an incident hip fracture and 400 controls
from 40 clinical centers around the U.S. for a case-control study nested
within the larger study.

All of the participants were postmenopausal (mean age 71, 95% white) and
were not using estrogens or other osteoporosis medications.

Serum vitamin D concentrations were measured at baseline and the
participants were followed annually with questionnaires for a mean of 7.1
years (range 0.7 to 9.3).

At baseline, concentrations were lower in the case patients than in the
controls (55.95 nmol/L versus 59.60 nmol/L, P=0.007).

For each 25-nmol/L decrease in vitamin D concentration, the risk of hip
fracture was increased by 33% (OR 1.33, 95% CI 1.06 to 1.68).

Risk of hip fracture decreased significantly from women in the lowest
quartile of vitamin D concentration (< 47.5 nmol/L) to those in the highest
(> 70.7 nmol/L) (P=0.016 for trend).

Read the full story:

http://www.medpagetoday.com/PrimaryCare/DietNutrition/tb/10590

The related study:

http://www.annals.org/cgi/content/abstract/149/4/242