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Public concern has been generated recently about the safety of statin therapy by reports of associations between statin use and various adverse health outcomes (for example, muscle pain, cataracts, and memory loss) in non-randomized “observational” studies.

Such studies typically involve comparisons of reported rates of adverse events in health care databases between people who have been prescribed statin therapy and those who have not been. However, people who are prescribed statins tend to differ from other people in many different ways (for example, they are often less healthy) that result in them having more adverse health outcomes (that is, related to their disease and not to their statin therapy). In addition, people who are prescribed statins may attribute health problems to their statin tablets when they are not really caused by the treatment (in particular, since statins can – very rarely – cause the serious muscle-related side-effect of “myopathy”, patients taking statins are advised to report any muscle problems). Consequently, in most circumstances, observational studies are not a reliable source of information about treatment effects.

By contrast, randomized controlled trials – such as those that are contributing to the CTT Collaboration – can provide reliable assessments about both the efficacy and safety of treatment. Firstly, by assigning the study treatment at random, the patients who are assigned to receive statin treatment are guaranteed to have similar risks of adverse health outcomes to those assigned control treatment. Secondly, by “blinding” the treatment assignment with placebo tablets, patients (and their doctors) cannot tell whether they are receiving active or dummy statin treatment. Consequently, statistically significant differences in the rates of health outcomes in the randomized placebo-controlled trials can be attributed to the statin treatment (rather than, as is potentially the case in non-randomized observational studies, being due to differences in the underlying risks of adverse health outcomes, or in the rates of reporting those outcomes, between the people who have been given a statin and those who have not).

Previously the CTT Collaboration demonstrated the efficacy of statin therapy at reducing the risks of vascular mortality and non-fatal major vascular events (such as heart attacks, strokes and revascularisation procedures) in many different types of patient, as well as the absence of harmful effects on any type of non-vascular causes of death or on any site-specific cancers. Now, in order to address concerns that have been raised about potential harmful effects, additional data are being sought on all adverse events recorded for each of the patients in all of the contributing randomized trials of statin therapy. Following detailed discussions, a protocol describing these plans was agreed by the CTT Collaboration and was accepted for publication in the American Heart Journal in 2016.

Paper describing value of randomized trial evaluation

Recent paper discussing statin tolerability: Eur J Cardiol 2015 Aug 28. pii: 2047487315602861. [Epub ahead of print]