Statins are associated with a low risk of adverse events in patients without a history of heart disease but the potential harms are small and should not deter their use in primary prevention, a new systematic review and meta-analysis concludes.
As reported July 14 in BMJ, the analysis showed a slightly increased risk for self-reported muscle symptoms after treatment with statins but no increased risk for clinically confirmed muscle disorders. Statins were associated with liver dysfunction, renal insufficiency, and eye conditions, but not with diabetes.
“These risks are very, very small and, in fact, the adverse events we’re talking about are potentially quite mild, so if you weigh them against the benefits in terms of reduction in major cardiovascular events, the benefit-to-harm ratio is very much in favour of prescribing treatment for almost all patients,” senior author James P. Sheppard, MD, University of Oxford, United Kingdom, told theheart.org | Medscape Cardiology.
Although there’s an abundance of data showing statins prevent recurrent cardiovascular events, their use is controversial in primary prevention, owing partly to the lower risk for cardiovascular disease (CVD). The absolute benefits of statins are smaller in primary prevention than in those with existing CVD, and the benefit-to-harm balance of treatment might be less favorable, the authors note.
A 2019 review suggested that the use of statins in primary prevention may be an example of “low-value care, having little benefit and potential to cause harm,” and a meta-analysis with more than 94,000 trial participants showed statins significantly increased risks for myopathy, renal dysfunction, and hepatic dysfunction.
Nevertheless, clinical guidelines have recommended wider use of statins for primary prevention, calling on physicians to weigh the benefits and harms.
“This is a reasonable expectation but, at present, the data on the harms of treatment are much less well understood in comparison to the benefits and there’s quite a lot of debate about the extent to which statins are associated with adverse events,” Sheppard said. “So we wanted to look at this in a bit more detail.”
The investigators analyzed results from 62 randomized controlled trials with 120,456 participants (mean age, 61; 40% women) followed for a mean of 3.9 years. All but two studies enrolled participants with hyperlipidemia or dyslipidemia. Common comorbidities were diabetes (11 studies), asymptomatic atherosclerosis (nine studies), and hypertension (four studies).
Statins increased risks for self-reported muscle symptoms in 21 trials (odds ratio [OR], 1.06), liver dysfunction in 21 trials (OR, 1.33), renal insufficiency in eight trials (OR, 1.14), and cataracts or other eye-related conditions in six trials (OR, 1.23).
At the same time, statins decreased risks for myocardial infarction in 22 trials (OR, 0.72), stroke in 17 trials (OR, 0.80), and CVD death in 22 trials (OR, 0.83).
These risks translated into 15 more events of muscle symptoms, eight more liver events, 12 more kidney events, and 14 more eye conditions per 10,000 patients treated for a year.
Statins were estimated to prevent 19 myocardial infarctions, nine strokes, and eight CVD deaths per 10,000 patients treated for a year.
Sheppard suggested that the inclusion of previously omitted trials and the decision to classify muscle problems as self-reported symptoms or clinically defined muscle disorders based on changes in creatine kinase might explain why they found the association with statins, whereas most systematic reviews have not.
“Some people would argue that these side effects are so small and so negligible that we shouldn’t talk about them, but the problem with doing that is if you’ve got a patient who has a preconceived idea that statins are harmful,” he added. “So having some empirical data where you can actually say: ‘look, just 15 people out of 10,000 patients who’ve been treated for a year might experience one of those self-reported muscle symptoms,’ hopefully, will be helpful for physicians having discussions in practice.”
The analysis is “another data point indicating the overall safety and net benefit of statins for patients, even in primary prevention,” Donald Lloyd-Jones, MD, ScM, chair of preventive medicine, Northwestern University Feinberg School of Medicine, Chicago, told theheart.org | Medscape cardiology.
He noted that the renal insufficiency findings are difficult to interpret, given that the endpoint was defined as “any decline in renal function,” but that most will have been clinically unimportant. In general, most studies didn’t systematically look to ascertain some of adverse events but relied on participant or physician report. “Nonetheless, there is little reason to suspect bias in the collection of these data among the blinded studies.”
“Although not definitive, given the study design and inclusion of very different types of studies and variable ascertainment of adverse events, the findings are reassuring that the risks of adverse events were small, and the potential adverse events identified were not very clinically significant and clearly outweighed by the important beneficial reductions in major cardiovascular events,” said Lloyd-Jones.
“This study is yet another reminder of the safety of statins,” Ann Navar, MD, PhD, a specialist in preventive cardiology at UT Southwestern Medical School, Dallas, said in an email. “I’m pleased to have a comprehensive study like this — a well-done, systematic review of randomized trials — to help combat the vast amounts of misinformation about statins circulating on the Internet.”
Lloyd-Jones also acknowledged the need to address misinformation, pointing out that the loss of contact with physicians and the adverse effects of the pandemic on weight and other health behaviors mean that many patients have had worsening of their cardiovascular risk factors.
“We must continue to help patients and the public understand that statins are beneficial for patients at sufficient risk for cardiovascular disease because of elevated cholesterol or their total burden of risk factors,” Lloyd-Jones said. “We must also be up front about the risks of potential side effects, which are uncommon and almost always very easily managed with wash out and dose reduction or switching to a different drug in the same class.”
Analyses by type of statin, however, showed few significant differences in adverse events. Rosuvastatin was associated with increased risks for self-reported muscle symptoms, renal insufficiency, diabetes, and eye conditions, whereas atorvastatin and lovastatin increased the risk for liver dysfunction.
In dose-response meta-analyses, a possible modest dose-response relationship was detected only for the effect of atorvastatin on liver dysfunction.
The current data do not support tailoring the type of statin or dosage to reduce adverse events, the authors say, although routine monitoring of liver function during treatment is probably warranted in primary prevention, given the increased risk for liver dysfunction.
To help improve adherence to statins, the investigators say additional studies are needed to identify patient characteristics crucial to the small risks of adverse events.
Limitations of the research, they say, are that many of the analyses were underpowered to detect between-group differences, many trials had short periods of follow-up, and some trials excluded vulnerable people more likely to have adverse events, such as those with high serum creatinine.
The study was funded by a British Heart Foundation PhD Scholarship held by first author Ting Cai. Sheppard reports receiving funding from a Wellcome Trust/Royal Society Sir Henry Dale Fellowship. Disclosures for other authors are listed in the paper. Lloyd-Jones and Navar report having no relevant financial conflicts of interest.
BMJ. 2021;374:n1537. Full text
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