Calcium and vitamin D reduced nonvertebral fractures and bone loss
ACP J Club. 1998 Mar-April; 128:47. doi:10.7326/ACPJC-1998-128-2-047
Dawson-Hughes B, Harris SS, Krall EA, Dallal GE. Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older. N Engl J Med. 1997 Sep 4;337:670-6.
To assess the effectiveness of combined calcium and vitamin D supplementation in reducing nonvertebral fractures and bone loss in community-living elderly persons.
3-year, randomized, double-blind, placebo-controlled trial.
Community-based study in the United States.
445 healthy, community-living persons who were ≥ 65 years of age (55% women) were enrolled, and 389 (mean age 71 y) completed the intention-to-treat analysis. Exclusion criteria were other serious illnesses; bisphosphonate, calcitonin, estrogen, tamoxifen, or testosterone use in the past 6 months; fluoride use in the past 2 years; or femoral-neck bone mineral density > 2 SD below the mean for persons of the same age and sex. Follow-up was 87%.
Participants were assigned to elemental calcium (calcium citrate malate), 500 mg/d, and vitamin D (cholecalciferol), 700 IU/d (n = 187), or to placebo (n = 202).
Main outcome measures
Nonvertebral fractures and bone mineral density in the femoral neck, spine, and total body measured every 6 months.
≥ 1 nonvertebral fracture occurred in 11 participants (5.9%) who received calcium and vitamin D and in 26 participants (12.9%) who received placebo (P = 0.02) (Table). Higher bone mineral loss was seen in the placebo group than in the calcium and vitamin D group in the total body (P < 0.001), femoral neck (P = 0.02), and spine (P = 0.04). Active treatment analysis showed increases in bone density in the calcium and vitamin D group at all sites at 1 year (P ≤ 0.05 for all comparisons), but only increases in total-body bone density were sustained at 3 years (P < 0.001).
Calcium and vitamin D supplementation decreased the risk for non-vertebral fractures, especially in women, and increased total-body bone mineral density in community-living elderly persons.
Sources of funding: National Institutes of Health and the Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging, Tufts University.
For article reprint: Dr. B. Dawson-Hughes, Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA 02111, USA.
Table. Calcium and vitamin D vs placebo*
|Outcome at 3 y||Calcium and vitamin D EER||Placebo CER||RRR (95% CI)||ARR |EER-CER|||NNT (CI)|
|Nonvertebral fractures||6%||13%||54% (12 to 77)||7%||15 (8 to 12)|
*Abbreviations defined in Glossary; RRR, ARR, NNT, and CI calculated from data in article.
The use of only calcium and vitamin D in individuals at risk for osteoporosis remains controversial (1). Current data suggest that low calcium intake is associated with accelerated bone loss, but well-designed randomized trials have found that among women with established osteoporosis, calcium and vitamin D are clearly inferior to estrogen (2), bisphosphonates (3), and calcitonin (4) in preventing fractures.
A large randomized controlled trial in older institutionalized women found that treatment with calcium and vitamin D reduced nonvertebral fractures by 33% compared with placebo (5). Should all elderly persons receive calcium and vitamin D to prevent osteoporotic fractures? Dawson-Hughes and colleagues shed some light on the issue, but several aspects of their study deserve comment.
Although the participants were older than 65 years, as a group they did not have low bone density, calcium intake, or vitamin D levels. The 19% rate of fracture over 3 years among women in the placebo group seems high for such healthy persons. It is likely that the true effect of calcium and vitamin D on risk for fracture is considerably less than the dramatic 50% reduction reported in this study. A more modest effect on rate of fracture is still consistent with the wide 95% CI in the study.
Is calcium and vitamin D treatment safe? Presumably yes, but large long-term studies have not been done. Such studies are needed before this treatment can be recommended for the prevention of fractures in all men and women older than 65 years.
Douglas C. Bauer, MD
University of San FranciscoSan Francisco, California, USA
3. Black DM, Cummings SR, Karpf DB, et al. Randomised trial of effect of alendronate on risk of fracture in women with existing vertebral fractures. Fracture Intervention Trial Research Group Lancet. 1996;348:1535-41.