BMJ  2008;336:404 (23 February), doi:10.1136/bmj.39493.484086.1F

Letters

Calcium supplementation

Data were misrepresented

The first 150 words of the full text of this article appear below.

The "What this study adds" box accompanying the article by Bolland et al misrepresents the study data.¹ The first bullet says that healthy older women randomised to calcium supplementation showed increased rates of myocardial infarction. Although the data show that women reported more events, analysis of New Zealand hospital records erased any significant difference in myocardial infarction rates between the calcium and placebo groups. The bulleted statement is not evidence based: the adjudicated results showed no significant increase in cardiovascular end points among women taking calcium. The authors characterised the between-group differences in event rates for myocardial infarction and the composite end point as being of "borderline significance." It cannot be concluded that the women showed "increased rates of myocardial infarction," because a "borderline" P value of 0.058 still means the events could occur by chance.

In addition, the authors’ statements in the body of the article do not fully . . . [Full text of this article]

¹ Midland Family Medicine Residency, 4005 Orchard Drive, Midland, MI 48670, USA

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Relevant Article

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

Mark J Bolland, P Alan Barber, Robert N Doughty, Barbara Mason, Anne Horne, Ruth Ames, Gregory D Gamble, Andrew Grey, and Ian R Reid
BMJ 2008 336: 262-266. [Abstract] [Full Text] [PDF]