The authors defend very carefully their observation that calcium supplements increase cardiovascular risk and discuss the hypothetical mechanisms. As calcium prescribers, one might be tempted to accept this notion, safe in the knowledge that calcium from nutrients is harmless and therefore preferable. However, patients rarely consume the recommended amount of calcium with their food, and for this reason, we should examine carefully the claim for harmful effects of calcium supplements. Without discussing the methodical selleck chemicals llc aspects of the two studies—the authors of the manuscript in this
issue do this extensively—a few considerations allow us to question their practical significance. First, we are entitled to retain from these publications only those results which were statistically significant. Data which are not significant should not be over interpreted. They can be noted as a trend, which should be considered—by definition—as not meaningful, not indicative and not notable, unless the lack of significance is taken as a message in
itself. This then excludes the increased risk of stroke and sudden death, which are reported as adverse effects of calcium supplements, and leaves us with the risk of myocardial infarction (MI) as the only significant negative event of calcium supplementation. TPX-0005 The significance stems from a meta-analysis . In the previous trial from the same authors , the risk of MI was no longer significantly increased once the data had undergone a quality control old audit using the national database of hospital
admissions. The meta-analysis of 15 trials demonstrated a significant increase of the risk of MI induced by calcium supplements, although none of the studies analysed individually resulted in significant results, even not the largest one. In the hierarchy of evidences, the Centre for Evidence-Based Medicine, Oxford, UK puts a meta-analysis with homogenous outcomes above the level of evidence provided by a randomized controlled trial (RCT), but this implies that the outcomes are primary or secondary, and not—as here in many cases—retrospectively defined outcomes. For this reason, this study is not a conventional meta-analysis. Some critics call it a ‘review of published trials’ . This leads to the following question: will a well-powered RCT with cardiovascular events as primary outcomes not have a comparable weight of evidence? According to Reid and colleagues , such trials cannot be envisaged for reasons of practicality and ethical obstacles. But there is one such study, and it showed no negative cardiovascular effects . Even accepting the result of this “meta-analysis”, we still should remember its Paclitaxel purchase context—namely, in the prevention of osteoporosis.