The Auckland calcium study: 5-year post-trial follow-up.
Study Goal
The researchers aimed to determine whether the effects of calcium supplementation on fracture incidence, bone mineral density (BMD), and cardiovascular safety persisted after discontinuation of the supplement.
Results Summary
Over 10 years, calcium supplementation showed no effect on total or hip fracture incidence but significantly reduced forearm and vertebral fractures. The initial adverse cardiovascular effects and BMD benefits did not persist post-trial.
Population
1,471 postmenopausal women
Effective Dosage
1 g/day calcium citrate
Duration
5 years
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
calcium supplements | no change | total fracture incidence | postmenopausal women | - | no effect | #1 |
calcium supplements | decrease | vertebral fractures | postmenopausal women | - | significant reduction | #2 |
calcium supplements | decrease | forearm fractures | postmenopausal women | - | significant reduction | #3 |
calcium supplements | no change | bone density | a subset | - | no effect | #4 |
calcium supplements | no change | cardiovascular events | - | - | no increased risk | #5 |
1 g/day calcium citrate | no change | total fracture incidence | 1,471 postmenopausal women | - | did not reduce | #6 |
1 g/day calcium citrate | no change | vertebral fracture incidence | 1,471 postmenopausal women | - | did not reduce | #7 |
1 g/day calcium citrate | no change | forearm fracture incidence | 1,471 postmenopausal women | - | did not reduce | #8 |
1 g/day calcium citrate | increase | hip fracture incidence | 1,471 postmenopausal women | - | increased | #9 |
1 g/day calcium citrate | increase | bone mineral density (BMD) | 1,471 postmenopausal women | - | had beneficial effects | #10 |
calcium | no change | total fracture | those assigned to calcium | HR 0.90, 95% CI 0.75-1.07 | no effect | #11 |
calcium | no change | hip fracture incidence | those assigned to calcium | 1.40, 0.89-2.21 | no effect | #12 |
calcium | decrease | forearm fractures | those assigned to calcium | 0.62, 0.43-0.89 | significant reductions | #13 |
calcium | decrease | vertebral fractures | those assigned to calcium | 0.52, 0.32-0.85 | significant reductions | #14 |
calcium | no change | BMD | - | - | no between-group differences | #15 |
calcium | no change | adverse cardiovascular outcomes | - | - | did not persist | #16 |
Calcium supplementation for 5 years | no change | total fracture incidence | - | - | had no effect | #17 |
Calcium supplementation | no change | positive benefits on BMD | - | - | did not persist | #18 |
Calcium supplementation | no change | adverse cardiovascular effects | - | - | did not persist | #19 |
UNLABELLED: Five years after completion of a randomised placebo-controlled trial of calcium supplements, there was no effect of calcium on total fracture incidence, a significant reduction in vertebral and forearm fractures and, in a subset, no effect on bone density. There was no increased risk of cardiovascular events after discontinuation of calcium. INTRODUCTION: The Auckland calcium study was a 5-year randomised controlled trial of 1 g/day calcium citrate in 1,471 postmenopausal women. Calcium did not reduce total, vertebral or forearm fracture incidence, increased hip fracture incidence and had beneficial effects on bone mineral density (BMD). A secondary analysis raised concerns about the cardiovascular safety of calcium. The purpose of this study was to determine whether the effects of calcium on fracture incidence, BMD and cardiovascular endpoints persisted after supplement discontinuation. METHODS: Approximately 5-years post-trial, we collected information on the 1,408 participants alive at trial completion from the national databases of hospital admissions and deaths. We contacted 1,174 women by phone, and from these we obtained information on medical events and post-trial calcium use. We undertook BMD measurements at 10 years in a selected subset of 194 women who took study medication for 5 years in the original trial, and did not take bone-active medications post-trial. RESULTS: Over the 10-year period, there was no effect on total fracture (HR 0.90, 95% CI 0.75-1.07) or hip fracture incidence (1.40, 0.89-2.21), but significant reductions in forearm (0.62, 0.43-0.89) and vertebral fractures (0.52, 0.32-0.85) in those assigned to calcium. There were no between-group differences in BMD at 10 years at any site. The adverse cardiovascular outcomes observed in the 5-year trial did not persist post-trial. CONCLUSION: Calcium supplementation for 5 years had no effect on total fracture incidence at 10 years. The positive benefits on BMD and the adverse cardiovascular effects did not persist once supplements were stopped.