Apr 24 2019 Posted: 15:44 IST
  • Studies illustrate the potential impacts of changes in clinical guidelines for primary prevention of cardiovascular disease
  • Clinical guidelines have widened eligibility for cholesterol lowering drugs (statins)
  • Evidence to support statin use is limited
  • Statin use impacts large proportion of Irish population and healthcare budgets with potential associated costs rising from €14 million to €107 million per annum

New research from the J.E. Cairnes School of Business and Economics at NUI Galway has examined the impacts of changes to recommendations of clinical guidelines for the prevention of cardiovascular disease. The study published today (24 April 2019) in the British Journal of General Practice, calculated that the proportion of a sample of people in Ireland aged over-50 who did not have cardiovascular disease but who could be eligible for statins (cholesterol lowering drugs), increased from 8% in 1987 to 61% in 2016.

Follow-up research to this study was also published today (24 April 2019) in the journal BMJ Open, which for the first time exclusively used primary prevention data that examined the evidence to support statin use in primary prevention and found considerable uncertainty as to whether statin use in people without cardiovascular disease is beneficial.

Background

Statins are cholesterol lowering drugs that are used to prevent cardiovascular disease. They are prescribed to those who already have established cardiovascular disease, (for example, those who have had a heart attack or stroke, which is referred to as secondary prevention) as well as those without prior cardiovascular disease (primary prevention). An earlier study by the researchers, published in September 2018, found that almost one third of adults in a sample of over-50 year olds in Ireland took statins. Of these, almost two thirds took statins for primary prevention of cardiovascular disease, but there was a notable difference between men and women. 57% of men who were taking statins did not have cardiovascular disease compared to 73% of women who were taking statins.

Statins are widely prescribed and command a large share of drug expenditure in Ireland and other countries. In 2016, statins ranked as fifth in terms of highest expenditure under the medical card scheme and the second most prescribed type of medicine on the scheme. An increasingly larger proportion of the population are using statins, and this is becoming very resource intensive and arguably unsustainable.

Summary of two new studies

The British Journal of General Practice study found that while in 1987, 8% of a sample of over-50’s who did not have cardiovascular disease could have been eligible for statins, by 2016, 61% of the same sample would be eligible, with associated costs rising from €14 million to €107 million per annum. In 1987, 40 of the people in the lowest risk category would have had to be treated to prevent one cardiovascular event and by 2016, 400 people would have to be treated for the same impact. The proportion of statin-eligible patients achieving risk reductions that patients regard as justifying taking a daily medicine, fell as guidelines changed over time.

The BMJ Open study examined the evidence that underpins statin use in people without cardiovascular disease. Before being prescribed a statin, it is recommended that a person’s baseline risk of cardiovascular disease is estimated. This can be determined by GP’s using risk calculators. If a person’s risk is estimated above a certain threshold, statin therapy may be recommended. In this study, the authors looked at the results from statin trials (reported in systematic reviews) according to peoples’ levels of risk. They found that in most categories of risk, there was considerable uncertainty as to whether statins could benefit the patient. For those who are already at low-risk of cardiovascular disease, the benefit (if there is one) may be so miniscule that it would not justify taking a daily medicine or taking the chance that they may experience side-effects.

From the perspective of overstretched healthcare budgets, statin use in some low-risk people may represent overuse of medicine and low-value care thus warranting more careful consideration.

Lead author of the studies, Paula Byrne, SPHeRE scholar, J.E. Cairnes School of Business and Economics, NUI Galway, said: “Increased eligibility for statin therapy impacts large proportions of our population and healthcare budgets. Decisions to take and reimburse statins should be considered on the basis of cost-effectiveness and acceptability to some low-risk patients. One would have to question whether some patients, who may achieve very small reductions in risk of cardiovascular disease by taking statins, would agree to take this medication were they fully informed. From a societal perspective, we need to ask whether or not statin use in such people represents value for money in the health sector.”

Findings

The overarching aim of the British Journal of General Practice study was to explore the impact of changing clinical guidelines on statins for the prevention of cardiovascular events over time, incorporating patient preferences regarding preventive treatments. This involved four analyses. First, the authors estimated the increasing proportions of people who would be considered eligible for statin treatment according to each of the seven European Society of Cardiology/European Atherosclerosis Society (ESC/EAS) guidelines from 1987 to 2016. Second, the authors estimated the potential cost increases associated with each consecutive guideline recommendation. Third, the ‘numbers-needed-to-treat’ (NNT) to prevent one major vascular event in patients at the lowest baseline risk for which each guideline recommended treatment was calculated, as well as for those at low, medium, high, and very-high risk according to the most recent 2016 guideline. Finally, the authors compared these ‘numbers-needed-to-treat’ with those reported by patients as being the minimum benefit they would need to justify taking a daily medicine.

Changes in recommendations for the use of statins have resulted in almost two thirds of over-50’s in Ireland and similar countries being considered eligible for statin therapy. This has implications for the medicalisation of large proportions of the Irish population, as well as for already resource constrained healthcare budgets. The value for money of the widening use of statins should be considered from both a societal and individual perspective. The decision to take and reimburse statins could be informed by ‘numbers-needed-to-treat’, which are large in some risk categories. As seen from the analysis, the researchers found a proportion of their sample would require significantly greater reductions in absolute risk to justify taking a daily medication of statins.

To read the full study on the analysis of changing clinical guidelines in the British Journal of General Practice, visit: https://bjgp.org/content/early/2019/04/22/bjgp19X702701

To read the full overview of systematic reviews describing the evidence to support statin use in primary prevention in BMJ Open, visit: https://bmjopen.bmj.com/content/9/4/e023085

To read the September 2018 study describing the proportion of statin users in an Irish sample in BMJ Open, visit: https://bmjopen.bmj.com/content/8/2/e018524

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