How old is too old for cholesterol lowering medications?
There is growing debate about whether doctors should prescribe statins to otherwise healthy older people to reduce their risk of developing their first heart attack or stroke.
Now the debate has reignited with the publication of a new analysis that casts doubt on their benefit for people over the age of 65, and raised concern of the potential for harm in people aged over 75.
Statins are the most commonly used cholesterol lowering medications in Australia. In 2010-2011 they were taken by 2.6 million Australians with 16 million scripts dispensed from June 2011 to June 2012.
They are prescribed to lower blood lipid levels and so reduce people’s chances of heart disease, including stroke, and to prolong life.
In particular, this class of drugs inhibits how the body makes low-density lipoprotein cholesterol or bad cholesterol.
Different statins reduce bad cholesterol to different extents. For example, atorvastatin and rosuvastatin produce larger reductions in bad cholesterol per milligram of drug than a different statin, pravastatin (about 50 per cent vs 30 per cent).
The issue of whether to prescribe statins for older people is particularly important given the growing segment of our population living into their 70s and 80s.
About one third of Australians over the age of 70 years are taking statins. And they could potentially be used by more older people as, based on their age alone, these are the people at highest risk of heart disease or stroke.
Doctors justify prescribing statins for this group by looking at a figure called the “number needed to treat”. In the case of statins, researchers calculate 28 people with existing heart disease or who had had a stroke would need to be treated for five years to prevent one death, a figure low enough to warrant treatment.
In people without heart disease or who have not had a stroke, the benefits of statins are less clear for those aged 70 years or older. Most national and international guidelines, including those from the Heart Foundation, have not been able to make strong recommendations to guide prescribing for older people. And any recommendations they do make are mostly based on trials of statins in people under the age of 70.
To complicate things further, pooling results of two of these trials finds statins reduce cardiovascular events in people aged under 65 years (by about 25 per cent), 65-70 years (by about 50 per cent) and over 70 years (by about 25 per cent).
Due to the conflicting figures, researchers have not pooled the results to calculate a “number needed to treat” for healthy older people taking statins to prevent their first heart attack or stroke.
The debate about the benefits of statins for older people also needs to take into account the increased likelihood of side-effects from medications in this age group.
Researchers have not well studied side effects with statin use in older people. However, the issues most likely to be of concern to older people are muscle aches and weakness, muddled thinking and diabetes.
What does the latest evidence say?
The latest analysis revisits selected results from a large trial completed some 13 years ago. The researchers considered data from 2,867 participants over 65 without any evidence of heart disease who were randomly assigned to the statin pravastatin or usual care, then followed for over 4.5 years.
The researchers looked at the effects of the statin on deaths from any cause, and deaths from heart disease and heart attacks in people aged 65-75 and over 75. They found no difference in any of these outcomes for either of the age groups and even raised concern of the potential for harm in people aged over 75.
The study authors concluded that the benefits previously ascribed to statins may have been overstated for older people.
To gauge what these new findings mean, we first need to consider the statin used in the study, pravastatin. Doctors don’t prescribe this so commonly to lower cholesterol nowadays because it has been replaced by stronger statins.
Second, by the end of the study many people in the statin group had stopped their treatment while people in the usual care group had started treatment, either on pravastatin or another statin. This makes it very hard to see which outcome could be the result of the drug itself.
Also, the study may not have included enough older people. Studies aiming to prevent disease in healthy people need many thousands as most will not suffer heart attacks and strokes irrespective of which treatment group they are in.
So where does that leave us?
To plug this gap in the research, we are conducting the first trial of its kind in the world to look at the effects of statins on healthy ageing.
This statin trial, which is unusual as it is not funded by the pharmaceutical industry, is the first randomised controlled trial of statins in healthy older Australians (aged 70 or older) living independently in the community.
When the results from its 18,000 participants are in, we will have a clearer picture of the effects of statins on overall survival, survival free of dementia and disability, as well as cardiovascular events over an average five years of treatment.
If you’re on statins, what should you do?
Older people with heart disease or who’ve had a stroke should continue taking their prescribed statin as the benefits are clear. However, they should discuss any side effects with their doctor.
Older people without heart disease or who have not had a stroke should discuss the potential benefits and harms of statins with their doctor before starting or continuing treatment.
This discussion should take into account a person’s preference for statins and other measures to reduce their risk of heart disease, include having a healthy diet, being physically active and stopping smoking.
Written by Sophia Zoungas. First appeared on The Conversation.