Researchers at Imperial College London and the University of Leicester estimate the measures could lead to 12,000 cardiovascular events – such as a heart attack or stroke – being averted among high-risk patients in the UK.
The paper, published in the journal JAMA Network Open, is the first to look at the combined effect of high intensity statin treatment and adherence in patients who have already had a cardiovascular event and who are at increased risk of it happening again, compared to the general public.
It found that those taking the highest doses of statins to reduce their low-density lipoprotein (LDL) cholesterol levels – the “bad” cholesterol which builds up in the arteries – and, crucially, who take the medication as advised by their doctor, saw the biggest reductions in risk for future cardiovascular events.
Patient adherence describes the degree to which a patient follows medical advice and takes medication correctly.
It can significantly affect how successful a treatment is, as patients may not take a drug regularly, skip days, or stop the medication altogether – especially if they see or feel no immediate benefit.
Researchers said this is particularly important as high cholesterol levels in the blood may not cause any noticeable symptoms.
Lead author Professor Kausik Ray, of Imperial College London, said: “The basic message here is that long-term adherence achieves better long-term cholesterol reductions, and in turn, achieves better long-term outcomes for patients.
“In terms of risk reduction, we can see the people who do the best are those who are adhering to the recommended dosage and are on more potent drug regimens.
“But if someone is not going to take a treatment as recommended, they may actually be better off on higher doses of statins.”
The study saw the team analyse patient data from the Clinical Practice Research Datalink (CPRD), which includes more than five million records from more than 450 GP practices.
They focused on three groups of patients at high risk of cardiovascular events – those with established heart disease, those with diabetes but no history of heart disease, and those with chronic kidney disease but no prior heart attack or stroke.
Almost 30,000 patients recently started on cholesterol lowering medications were scored using a measure which combined the intensity of treatment they received (statins alone or combined with another cholesterol-lowering drug called ezetimibe) and their adherence – with those who took their medication as prescribed 80 per cent of the time classed as “adherent”.
When researchers measured the relative risk reduction compared to untreated patients an average of three years after treatment, they found those patients with the highest score (who were on the highest intensity treatment and had the highest adherence) had the greatest reduction in LDL cholesterol levels and cardiovascular risk, with a 40 per cent drop in their risk of cardiovascular events.
By comparison, those patients on the lowest intensity treatment and with poor adherence had a risk reduction of just 5 per cent compared to those not on medication.
To improve adherence, the researchers advise that doctors spend more time with patients to explain the benefits and risks of the drugs, so they are able to make better decisions about their own health.
They add that adherence could be improved with new delivery methods, such as slow release drugs which patients take less frequently.
Prof Ray said there is a lot of confusion around dietary cholesterol and medications that lower cholesterol.
He added: “While changing your diet is a good thing, it may not be enough for those patients who are already in the high-risk groups – such as those with heart disease. Here, statins provide additional benefits over and above lifestyle.
“It doesn’t matter how patients get to this point – through obesity, smoking, genetic risk factors – what we know is that once you have one heart attack or other cardiovascular event, you are at much higher risk of more events in future and that lowering your LDL cholesterol levels is key to improving outcomes.
“For these patients, taking the right medication, at the right dose, at the right time – and sticking to this regimen – is critical in lowering their risk of future cardiovascular events.”