Do heart benefits of statins outweigh diabetes risk?

‘Heart benefits of statins outweigh diabetes risk’, The Daily Telegraph says.

Statins are a type of medication widely used to lower blood cholesterol levels. While statins have proved reasonably effective in preventing cardiovascular disease (CVD), concerns have been raised that they could be associated with an increased risk of type 2 diabetes.

The Telegraph’s story is based on a large, five-year study from the US that was seeking to clarify the ‘risk-benefit balance’ between:

The key findings of the study were that:

The researchers calculated that by treating the (roughly) 11,000 people in this trial who had risk factors for diabetes, 134 CVDs or deaths would be avoided for every 54 extra cases of diabetes caused.

The findings of this trial will need to be evaluated alongside other evidence, but do suggest the benefits of statins outweigh the potential risks.

 

The study was carried out by researchers from the Center for Cardiovascular Disease Prevention and the Division of Cardiovascular Medicine at Brigham and Women’s Hospital, Harvard Medical School, USA, and was funded by the drug company AstraZeneca. The study was published in the peer-reviewed medical journal, The Lancet.

The Telegraph accurately reported the main findings of this study, but it may have been more useful to readers if it had provided the actual numbers of people who might benefit. This would help both health professionals and patients to make a more informed decision about whether the benefits of statins are worth the risk.

 

This was a randomised controlled trial which aimed to look at the benefit of statins in reducing the risk of cardiovascular events, and look at whether they increased the risk of type 2 diabetes, compared to an inactive placebo drug. The study population were people with no history of cardiovascular disease events; that is, the study was looking at the use of statins for primary prevention of cardiovascular disease (use of statins in people who have already had a heart attack or stroke would be secondary prevention).

A randomised controlled trial is the best way of looking at the risks and benefits of any intervention compared to a comparator. This particular trial further benefits from being of a large size, and including a reasonable length of follow-up (five years).

 

The JUPITER (Justification for Use of statins in Prevention: an Intervention Trial Evaluating Rosuvastatin) trial included 17,802 men and women (average age 66 years) who were randomised to take either 20mg daily of rosuvastatin or an inactive placebo drug for five years.

All participants were healthy, without known heart disease or diabetes, although 65% did have one or more major risk factor for diabetes, including:

Participants were followed over the course of the five years, and the main outcome of interest was a combined cardiovascular outcome, such as:

Other outcomes of interest were doctors' diagnosis of diabetes, or venous thromboembolism (blood clot in the veins).

The trial was double blind, meaning that neither participants nor researchers knew whether statin or placebo had been taken.

After exclusion of those who were found to have diabetes at study start or who had missing data, 17,603 (99%) were included in the analyses. People with one or more major risk factor for diabetes (11,508) and those without (6,095) were analysed separately.

 

Overall, in all participants of the trial there were 270 reports of diabetes in people randomised to take rosuvastatin compared to 216 in the placebo group – a risk increase of 25% (hazard ratio [HR] 1.25, 95% confidence interval  (CI) 1.05 to 1.49). The average time from randomisation to diagnosis of diabetes was 84.3 weeks in the rosuvastatin group vs. 89.7 weeks in the placebo group: an acceleration of 5.4 weeks.

When analysed separately by group, for people with one or more risk factor for diabetes, statin treatment gave:

People without diabetes risk factors had:

The researchers calculated that if the number of people in this trial who had diabetes risk factors take a statin, then 134 cardiovascular events or deaths would be avoided for every 54 new cases of diabetes diagnosed. If the number of people in this trial without diabetes risk factors take a statin, 86 cardiovascular events or deaths would be avoided with no new cases of diabetes diagnosed.

 

The researchers conclude from their trial that the cardiovascular benefits of taking a statin outweigh the risk of diabetes, even in people at high risk of diabetes.

 

This is a well conducted trial intending to weigh up the cardiovascular benefit against the diabetes risk of taking a statin. The large trial benefits from being double blind (neither participants nor researchers aware of study treatment) and including a reasonable length of follow-up.

Overall, the researchers find that amongst roughly 11,000 people with diabetes risk factors (such as metabolic syndrome or raised fasting glucose levels in the blood) 134 cardiovascular events or deaths would be avoided for every 54 extra cases of diabetes caused by taking a statin.  Amongst roughly 6,000 people without diabetes risk factors who take a statin, 86 cardiovascular events or deaths would be avoided with no new cases of diabetes diagnosed.

These are important findings which add to the evidence on the benefit of statins for reducing cardiovascular events, and to the risk increase for diabetes.

It must be noted that the trial was examining the use of one statin for ‘primary prevention’ – that is, in people who have not suffered a cardiovascular event such as heart attack or stroke. It has not examined use of statins for secondary prevention in people who have already had a cardiovascular event, although the researchers say that in this group the diabetes risk is considered to be low compared with the reduced risk of having another cardiovascular event.

Also, the study has only examined one statin – rosuvastatin – though previous research has suggested that all statin drugs are associated with a similar small increased risk. The study has also only examined the medium dose of 20mg, and other research suggests that the risks may be dose-dependent and higher doses may be associated with higher risk.

When prescribing any drug its benefits and potential risks need to be taken into account. The findings of this trial will need to be evaluated alongside other evidence of the risks and benefits of statins at different doses and in different treatment groups. However, overall the findings confirm the net benefits of statins.

Analysis by NHS Choices. Follow Behind the Headlines on twitter.

 

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