A major review of the available evidence on the safety and efficacy of statin therapy has concluded that the benefits have been underestimated and the harms exaggerated, due to a failure to properly acknowledge the wealth of evidence from randomised trials and the limitations of other types of studies.
The review, which was carried out by the Clinical Trial Service Unit (CTSU), at the University of Oxford, intends to help doctors, patients and the public make informed decisions about the use of the drugs. Research on statins has been ongoing for over 30 years, and this has generated a large amount of data.
The review explains how the available evidence on the efficacy and safety of statin therapy should be interpreted, and concludes that lowering cholesterol by 2 mmol/L with an effective low-cost statin for 5 years in 10,000 patients would:
- Prevent major cardiovascular events (heart attacks, ischaemic strokes and coronary artery bypasses) in 1000 people with pre-existing vascular disease (“secondary prevention”), and in 500 people who are at increased risk (eg, due to their age or having hypertension or diabetes) but have not yet had a vascular event (“primary prevention”).
- Cause 5 cases of myopathy (one of which might progress to the more severe condition of rhabdomyolysis, if the statin is not stopped), 5-10 haemorrhagic strokes, 50-100 new cases of diabetes and up to 50-100 cases of symptomatic adverse events (such as muscle pain).
The authors note that although further research may identify small additional beneficial or adverse effects, this is unlikely to materially alter the balance of benefits and harms for patients because of the evidence generated so far.
The review author, Professor Rory Collins, says:
“Our review shows that the numbers of people who avoid heart attacks and strokes by taking statin therapy are very much larger than the numbers who have side-effects with it. In addition, whereas most of the side-effects can be reversed with no residual effects by stopping the statin, the effects of a heart attack or stroke not being prevented are irreversible and can be devastating. Consequently there is a serious cost to public health from making misleading claims about high side-effect rates that inappropriately dissuade people from taking statin therapy despite the proven benefits.”
Professor Liam Smeeth, from the London School of Hygiene & Tropical Medicine, commented:
“The best available scientific evidence tells us that statins are effective, safe drugs that have a crucial role in helping prevent cardiovascular disease: the leading cause of morbidity and mortality worldwide.”
The review is published in The Lancet.