Reporting in the BMJ, the research team say their findings should reassure patients and the concern about safety should not deter their use of statins, since the benefit-to-harm balance of treatment for adults at risk of but without previous heart disease is generally favourable.
Statins are widely used to prevent heart disease, and severe side effects are rare, but many people are reluctant to take them because of the potential for milder effects such as muscle weakness and stiffness.
For people with existing heart disease, the benefits of statins far outweigh the risk of these effects, but when statins are used by people without a history of heart disease (known as primary prevention) the benefit-to-harm balance of treatment might be less favourable. Yet recent guidelines have recommended wider use of statins for primary prevention.
So, a team from the University of Oxford and the University of Southern California set out to examine the associations between statins and adverse events in adults without a history of heart disease, and how they vary by type and dose of statins.
They analysed the results of 62 randomised controlled trials with 120,456 participants (average age 61; 40% women) followed up for an average of 3.9 years. The trials were designed differently, and were of varying quality, but the researchers were able to allow for that in their analysis.
Statins were associated with a slightly increased risk of self-reported muscle pain, liver and kidney problems, and certain eye conditions such as cataracts, but were not associated with clinically confirmed muscle disorders or diabetes.
These risks equated to 15 more instances of muscle symptoms, eight more liver events, 12 more kidney events, and 14 more eye conditions per 10,000 patients treated for a year. However, these increased risks did not outweigh the reduction in the risk of major cardiovascular events. The study estimated statins prevented 19 heart attacks, nine strokes, and eight deaths from cardiovascular disease per 10,000 patients treated for a year
The project was led by DPhil student Ting Cai as part of her British Heart Foundation-funded studentship. Commenting, Ting said: "This is a large study including data from 62 clinical trials and more than 120,000 people, and should reassure patients and their physicians who are considering using statins to prevent heart attack, stroke and other cardiovascular diseases. We found the risk of patients experiencing even mild side effects from taking statins was low, so the balance of benefit to harm is favourable. Our analyses also found no current evidence from trials to suggest that tailoring statin regimens to deal with safety concerns when starting treatment is needed.”
In the study, analyses by type of statin showed that atorvastatin, lovastatin, and rosuvastatin were associated with some adverse events, but few significant differences were seen between the statins. A possible modest dose-response relationship was identified for the effect of atorvastatin on liver dysfunction, but the dose-response relationships for the other types of statins and adverse effects were inconclusive.
This was a large study that was able to accurately assess the adverse effects of treatment with statins. But the researchers point to some limitations in trial design that may have led to events being underestimated or more severe long-term events being missed. They agree that clearing up patients' misperception of statin-related muscle problems is important and monitoring of liver function during treatment is probably warranted in primary prevention, and say further studies are needed to help improve adherence to treatment and achieve more efficient monitoring.
Read more in the BMJ https://www.bmj.com/content/374/bmj.n1537