Researchers from the Cholesterol Treatment Trialists’ (CTT) Collaboration set out plans to assess whether statin therapy is associated with a range of reported adverse health outcomes. The plans were described in a protocol accepted for publication in the American Heart Journal in 2016.
Public concern about statin safety had increased following reports from non-randomised observational studies linking statin use with health problems such as muscle pain, cataracts and memory loss. However, these studies can be affected by differences between people who are and are not prescribed statins, making it difficult to determine whether the treatment caused the reported conditions.
People prescribed statins are often less healthy than those who are not and may therefore already have a greater risk of adverse health outcomes. They may also be more likely to report certain symptoms because they have been advised to look out for them. For example, statins can very rarely cause a serious muscle condition known as myopathy, so patients are encouraged to report muscle-related problems.
Randomised placebo-controlled trials provide a more reliable way to assess both the benefits and risks of treatment. Participants are assigned by chance to receive either statin therapy or a control treatment, helping to ensure that the groups have similar underlying risks of adverse health outcomes.
In blinded trials, neither participants nor their doctors know whether active treatment or a placebo has been assigned. Differences in health outcomes between the groups can therefore be more confidently attributed to statin therapy rather than to differences in participants’ health or in how symptoms are reported.
Previous research from the CTT Collaboration showed that statin therapy reduces the risk of death from vascular disease and of major non-fatal vascular events, including heart attacks, strokes and procedures to restore blood flow. It also found no evidence that statins increase the risk of death from non-vascular causes or of cancer at any specific site.
To investigate concerns about other possible adverse effects, the CTT Collaboration sought additional information on all adverse events recorded among participants in the randomised trials included in its work.
The planned analysis was designed to provide a more reliable assessment of the benefits and possible risks of statin therapy using detailed adverse-event data from randomised trials.