Statins – drugs that are used to lower cholesterol – can prevent heart attacks for at least a decade after people stop taking them, report The Times and The Daily Telegraph today. The Times suggests that this study “offers dramatic evidence of [statins’] long-lasting ability to halt and even reverse the progression of heart disease.” The researchers found that “there was a 25 per cent lower risk of heart attack or death from heart disease among those in the statin group, when compared with the placebo group”, The Daily Telegraph explained.
The evidence is growing that statins provide dramatic and long-lasting benefits in preventing deaths from heart disease, with very few adverse effects. This new study helps to reassure people taking these drugs that the benefits are long lasting. As it is unclear from this study how many people carried on with statins or were prescribed them for the first time following the completion of the main study, it is likely that the benefits of long-term statin use are even higher.
Where did the story come from?
Dr Ian Ford and colleagues from the West of Scotland Coronary Prevention Study Group based in Glasgow carried out this research. The original study was funded by a pharmaceutical company – Bristol-Myers Squibb – the manufacturer of the statin drug used in the trial. This follow-up study was supported by a grant from the Scottish Executive Health Department. The study was published in the peer-reviewed medical journal the New England Journal of Medicine.
What kind of scientific study was this?
This was a follow-up study of a randomised controlled trial that used electronic health records to obtain follow-up, health-related details on the original participants of the trial. The researchers were the same group who had published the results of a five year trial into the prevention of coronary heart disease in 6,595 men taking pravastatin (a cholesterol-lowering statin) for high blood cholesterol in 1995.
This new study reports long-term follow-up data for most of the men enrolled in the original trial. This data was collected from three Scottish morbidity and death registers – the hospital discharge records, the cancer registry and the General Register Office death records, held by the statistical division of NHS for Scotland. The researchers recorded the numbers and causes of death or other illnesses for which a hospital admission and discharge occurred, from these databases. They then used this data and the length of time from the randomisation part of the initial study until these occurrences for their analyses.
What were the results of the study?
The results of the study show that five years after the trial ended, just over a third of men in both the original statin group and about the same proportion in the placebo group were still taking a statin. When the records were analysed for deaths and non-fatal heart attack, the risk of death from coronary heart disease or of suffering a heart attack in the 10 years immediately after the end of the trial was 10.3% in the placebo group and 8.6% in the statin group. Over the entire 15–16 year period, this rate was 15.5% in the placebo group and 11.8% in the statin group.
What interpretations did the researchers draw from these results?
The researchers concluded that five years of treatment with pravastain was associated with a reduction in coronary events for the following 10 years, in men with high cholesterol who did not have a history of heart attack. This was achieved without an overall increase in risk of death from non-cardiovascular causes or cancer.
What does the NHS Knowledge Service make of this study?
Detailed information on statin use throughout the 10 year follow-up period was not available, and the authors indicate that this was due to funding constraints. This lack of data means that we are unsure how many men in either arm of the study might have started or re-started statins during the follow-up decade after the trial finished. Two additional factors are considered by the authors:
- that the prescribing of statins has increased in the 10 years since the first study was published; and
- that as the men aged, more men would have had a reason to start a statin because of recognised indications such as an increased cardiovascular risk.
Both these factors are likely to have increased the statin use amongst both the original statin and the placebo groups and may have led to an underestimation of the treatment effect, measured by a difference in mortality between the groups.
This long-term follow-up study of a randomised trial shows that the mortality benefits of statin use and the lack of serious adverse events are maintained for at least 10 years after use of the statin has stopped, whether people continue to take statins or not. It is not clear from this study, but could be expected, that continuing statins would provide even more benefit than stopping them. The headlines should not be interpreted as saying that stopping medication is advisable.
Sir Muir Gray adds...
The evidence for statins shows that the balance of benefit versus harm is good and if anything this improves it. It has been proposed that statins could be delivered as part of a 'polypill', a combination of several drugs that all play a part in reducing the risk of cardiovascular disease. At present, this is still a concept, but such a treatment may deliver even better results.