> Vascular events in healthy older women receiving calcium
> supplementation: randomised controlled trial

> Mark J Bolland, research fellow1, P Alan Barber, senior
> lecturer, Robert N Doughty, associate professor, Barbara
> Mason, research officer, Anne Horne, research fellow,
> Ruth Ames, research officer, Gregory D Gamble, research
> fellow, Andrew Grey, associate professor, Ian R Reid,
> professor

> Department of Medicine, Faculty of Medical and Health
> Sciences, University of Auckland, Private Bag 92019,
> Auckland, New Zealand

> OBJECTIVE: To determine the effect of calcium
> supplementation on myocardial infarction, stroke,
> and sudden death in healthy postmenopausal women.

> DESIGN: Randomised, placebo controlled trial.

> SETTING: Academic medical centre in an urban setting
> in New Zealand.

> PARTICIPANTS: 1471 postmenopausal women (mean age 74):
> 732 were randomised to calcium supplementation and 739
> to placebo.

> MAIN OUTCOME MEASURES: Adverse cardiovascular events
> over five years: death, sudden death, myocardial
> infarction, angina, other chest pain, stroke,
> transient ischaemic attack, and a composite end point
> of myocardial infarction, stroke, or sudden death.

> RESULTS: Myocardial infarction was more commonly
> reported in the calcium group than in the placebo
> group (45 events in 31 women v 19 events in 14 women,
> P=0.01). The composite end point of myocardial
> infarction, stroke, or sudden death was also more
> common in the calcium group (101 events in 69 women
> v 54 events in 42 women, P=0.008). After adjudication
> myocardial infarction remained more common in the
> calcium group (24 events in 21 women v 10 events
> in 10 women, relative risk 2.12, 95% confidence
> interval 1.01 to 4.47). For the composite end point
> 61 events were verified in 51 women in the calcium
> group and 36 events in 35 women in the placebo group
> (relative risk 1.47, 0.97 to 2.23). When unreported
> events were added from the national database of
> hospital admissions in New Zealand the relative risk
> of myocardial infarction was 1.49 (0.86 to 2.57) and
> that of the composite end point was 1.21 (0.84 to
> 1.74). The respective rate ratios were 1.67 (95%
> confidence intervals 0.98 to 2.87) and 1.43 (1.01 to
> 2.04); event rates: placebo 16.3/1000 person years,
> calcium 23.3/1000 person years. For stroke
> (including unreported events) the relative risk
> was 1.37 (0.83 to 2.28) and the rate ratio was 1.45
> (0.88 to 2.49).

> CONCLUSION: Calcium supplementation in healthy
> postmenopausal women is associated with upward
> trends in cardiovascular event rates. This
> potentially detrimental effect should be balanced
> against the likely benefits of calcium on bone.