Why the over-treatment of risk factors for heart attacks and strokes may do more harm than good
TORONTO – LIVING – Modern medical practice is engaged in a battle, not for hearts and minds, but for the conversion of perfectly healthy people into patients, labelled “at high risk” of various diseases in the name of prevention. However, a substantial majority of persons so labelled will not benefit despite the significant costs of preventive interventions; some may be harmed.
This “medicalization” of healthy persons, especially after mid-life, arises largely from ever lower cut-offs for treatment of risk factors for cardiovascular diseases (CVD) — heart attacks and strokes. Modest elevations of blood pressure and blood cholesterol, for example, typically cause no symptoms until they have been present for decades. Over-treatment of these risk factors can do more harm than good.
Controversy on both sides of the Atlantic surrounds new thresholds for cholesterol treatment in the U.S. (2013) and the UK (2014), which recommend the statin family of drugs, indefinitely and daily, for one quarter to one-third of the healthy older-adult population. Canadian doctors often look to U.S. and UK guidelines for guidance.
The specific concern is this: millions of additional persons with no symptoms will now be prescribed statins. But for many, their absolute risk of cardiovascular disease is quite low, and their first heart attack or stroke is many years to decades away.
The new guidelines are not simple to communicate to patients – the UK evidence fills more than 500 pages. But here’s the bottom line: there is now a significantly lowered risk-threshold for starting statins (from 20 percent to 10 percent – the likelihood that a given healthy patient will have a heart attack or stroke in the next 10 years. In the U.S., that cut-off is even lower – at 7.5%).
Let’s measure this another way: as the number of person-years of treatment required for each patient who clearly benefits — i.e., their heart disease or stroke is prevented. Persons just above the new risk-thresholds must undergo 300 (UK) to 400 (U.S.) person-years of treatment to prevent each heart disease or stroke. This compares with less than 200 person-years at the previous treatment threshold (itself hardly a small number).
Statins do have impressive benefits compared to risks for people who have significantly higher CVD risk levels, and in persons who have had symptoms of heart attack or stroke. But this is not the case for everyone.
What is driving these guideline changes?
The continuing fall in the price of powerful generic statins has converted statins prescribed for these lower risk thresholds into a competitive health economic investment. In other words, the new guidelines meet NICE (National Institute of Health and Care Excellence) criteria in the UK for “quality-adjusted years of life gained, per pound sterling spent.”
The societal cost implications of the new guidelines are, however, breath-taking: £285 million cost annually to the NHS; much more in the USA.
Guideline advocates claim the guidelines will reduce the rate of heart attacks and strokes in those treated by a third or more. Critics, however, point out that many patients, citing side-effects such as muscle discomfort, simply won’t continue taking statins long-term. Also, next to nothing is known about the long-term safety of the newer, high-potency statins. Large groups of patients on statins have only been followed-up for 10-15 years, and many of them were on older, less potent statins.
Worrisomely, even this limited follow-up has recently found one new case of Type 2 diabetes per 700 person-years of statin treatment. But if it has taken epidemiologists more than two decades to discover the statin/Type 2 diabetes link, what other subtle and delayed side-effects of statin use are we not yet aware of?
Discovery of just one additional side-effect of similar seriousness and frequency would virtually wipe out the net benefits at the new thresholds for statins.
Some physicians and researchers are asking: “Is this really how we want to spend our scarce healthcare resources?” In terms of preventing cardiovascular disease specifically, why not work harder on promoting non-smoking, healthy diet and physical activity instead? These lifestyle risk-factors are reversible without drugs, and still constitute the fundamental “upstream” causes of heart disease. Lifestyle changes population-wide would also yield spin-off benefits in preventing certain cancers and other chronic diseases not affected by statins.
This is where the controversy currently sits. Many physicians are reluctant to follow the new guidance. In the interim, the increased complexity of such closely balanced risks and benefits will require clinicians to more skilfully engage patients’ personal values and preferences before starting statins.
John Frank is an expert advisor with EvidenceNetwork.ca and Chair, Public Health Research and Policy, Medicine and Veterinary Medicine at the University of Edinburgh. His book, Prevention: A (Very) Critical View, will be published by Oxford University Press in late 2015.