Limited evidence for benefit of statins in primary prevention
MedWire News: A systematic review of statins in primary prevention found their use is associated with significant reductions in all-cause mortality, cardiovascular events, and revascularization rates.
The Cochrane Review, which included 14 randomized controlled trials, also found no evidence of harm caused by statin use.
However, the authors say that robust analysis was hampered by "evidence of selective reporting of outcomes, failure to report adverse events and inclusion of people with cardiovascular disease."
They conclude: "Only limited evidence showed that primary prevention with statins may be cost effective and improve patient quality of life."
The independent review was undertaken by Fiona Taylor (London School of Hygiene and Tropical Medicine, UK) and team, who searched the literature for randomized controlled trials of statins in people without a history of cardiovascular disease (CVD).
In all, 14 trials with a total of 34,272 patients were included in the meta-analysis; in 11 trials, the patients had specific conditions such as hyperlipidemia, hypertension, or diabetes. All trials compared statins with usual care or placebo, had a minimum treatment duration of 1 year, and a minimum follow-up duration of 6 months.
Statin therapy was associated with a significant reduction in several endpoints, including all-cause mortality (relative risk [RR]=0.83), the combination of fatal and non-fatal CVD (RR=0.70), and rates of revascularization (RR=0.66).
Both total and low-density lipoprotein cholesterol levels were reduced in all 14 trials; however, there was marked heterogeneity for these endpoints, which the researchers say is most likely due to differences in statin type and dosage.
There was insufficient evidence to draw conclusions about the cost-effectiveness of statin therapy, with only one trial examining this issue, and there were no reliable data on patient's quality of life or effects in patient subgroups.
Taylor et al say their review "highlights the shortcomings in the published trials of statins for primary prevention," which they believe "make the evidence impossible to disentangle."
They conclude: "We recommend that caution should be taken in prescribing statins for primary prevention among people at low cardiovascular risk."
In an accompanying Editorial, Carl Heneghan (University of Oxford, UK) noted that the current review findings are at odds with previous reviews such as the Cholesterol Treatment Trialists' Collaboration's Review, which found large reductions in major vascular endpoints in the subgroup of people without a history of myocardial infarction or coronary heart disease.
However, he points out, these populations either had established vascular disease or were at high risk based on risk factors.
"Therefore, if participants with pre-existing CVD, or at high risk of disease, are included in primary prevention trials, their elevated baseline risk significantly affects the overall benefit to harm ratio for statin use," Heneghan writes.
"The Cochrane Review guidance is helpful in highlighting that the current evidence does not support use of statins below a 1% annual all-cause mortality risk or an annual CVD event rate of below 2%."
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By MedWire Reporters