Bolland MJ, Avenell A, Baron JA, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010 (Review; meta-analysis)
DOI: 10.1136/bmj.c3691
http://www.bmj.com/cgi/content/abstract/341/jul29_1/c3691
http://www.bmj.com/cgi/content/full/341/jul29_1/c3691
http://www.bmj.com/cgi/reprint/341/jul29_1/c3691.pdf
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related:
Cleland JGF, Witte K, Steel S. Calcium supplements in people with osteoporosis. BMJ 2010;341:c3856-c3856. (Editorial)
DOI: 10.1136/bmj.c3691
http://www.bmj.com/cgi/content/full/341/jul29_1/c3856
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Published 29 July 2010, doi:10.1136/bmj.c3691
Cite this as: BMJ 2010;341:c3691
Research
Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis
Mark J Bolland, senior research fellow1, Alison Avenell, clinical senior lecturer2, John A Baron, professor3, Andrew Grey, associate professor1, Graeme S MacLennan, senior research fellow2, Greg D Gamble, research fellow1, Ian R Reid, professor1
1 Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92 019, Auckland 1142, New Zealand, 2 Health Services Research Unit, University of Aberdeen, 3 Department of Medicine, and Department of Community and Family Medicine, Dartmouth Medical School, NH, USA
Correspondence to: I R Reid i.reid@auckland.ac.nz
Objective To investigate whether calcium supplements increase the risk of cardiovascular events.
Design Patient level and trial level meta-analyses.
Data sources Medline, Embase, and Cochrane Central Register of Controlled Trials (1966-March 2010), reference lists of meta-analyses of calcium supplements, and two clinical trial registries. Initial searches were carried out in November 2007, with electronic database searches repeated in March 2010.
Study selection Eligible studies were randomised, placebo controlled trials of calcium supplements (500 mg/day), with 100 or more participants of mean age more than 40 years and study duration more than one year. The lead authors of eligible trials supplied data. Cardiovascular outcomes were obtained from self reports, hospital admissions, and death certificates.
Results 15 trials were eligible for inclusion, five with patient level data (8151 participants, median follow-up 3.6 years, interquartile range 2.7-4.3 years) and 11 with trial level data (11 921 participants, mean duration 4.0 years). In the five studies contributing patient level data, 143 people allocated to calcium had a myocardial infarction compared with 111 allocated to placebo (hazard ratio 1.31, 95% confidence interval 1.02 to 1.67, P=0.035). Non-significant increases occurred in the incidence of stroke (1.20, 0.96 to 1.50, P=0.11), the composite end point of myocardial infarction, stroke, or sudden death (1.18, 1.00 to 1.39, P=0.057), and death (1.09, 0.96 to 1.23, P=0.18). The meta-analysis of trial level data showed similar results: 296 people had a myocardial infarction (166 allocated to calcium, 130 to placebo), with an increased incidence of myocardial infarction in those allocated to calcium (pooled relative risk 1.27, 95% confidence interval 1.01 to 1.59, P=0.038).
Conclusions Calcium supplements (without coadministered vitamin D) are associated with an increased risk of myocardial infarction. As calcium supplements are widely used these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population. A reassessment of the role of calcium supplements in the management of osteoporosis is warranted.
© Bolland et al 2010
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