A 50% improvement in people sticking to long term treatment with statins would stave off twice as many deaths from stroke and heart attack as giving the drugs to a wider range of people, suggests research published ahead of print in the Journal of Epidemiology and Community Health.
The UK body for the evaluation of health technologies and medicines, the National Institute for Health and Clinical Excellence (NICE), recommends that anyone with a 20% or greater chance of having a heart attack or stroke over the next 10 years should be prescribed a statin.
But only around half those prescribed these drugs to ward off cardiovascular disease are still taking them five years later, the evidence shows.
The authors reviewed published research on the sustained use of statins in the primary and secondary prevention of cardiovascular disease, both within clinical trials and in routine practice, to calculate an assumed average of the capacity to stick to treatment over 10 years.
They then used data on blood pressure and total cholesterol for more than 38,000 patients taking part in the Melbourne Collaborative Cohort Study, to calculate the likelihood of developing cardiovascular disease and the advantages of preventive strategies.
Participants, who all had an average age of 55 when the study began, included some smokers and people with diabetes, both of which influence cardiovascular disease risk.
They then calculated risk scores according to three different scenarios: using the current NICE guidelines; increased adherence to drug treatment; and lowering the threshold for starting on statins, so extending the numbers of people treated.
On the basis of risk factors among participants in the Melbourne study, some 5390 new cases of cardiovascular disease and 710 related deaths would be expected over 10 years.
Almost one in four (24%) would be eligible for statin treatment under NICE guidelines. If half (4563) of these fully complied with statin treatment, an estimated 174 cases of cardiovascular disease and 70 deaths would be prevented.
Widening the starting treatment criteria to allow for 6991 people to take statins over the long term, would avert an additional 70 cases of cardiovascular disease and 18 related deaths.
But improving long term compliance with treatment for 6971 people would prevent an additional 91 cases of cardiovascular disease and stave off 37 related deaths - roughly twice as many as relaxing the starting treatment threshold.
The authors say that it is not so surprising that concentrating on people at greatest risk, rather than including those at lower risk of cardiovascular disease, should yield more impressive results.
"However, the magnitude of the difference is notable," they say. "And it serves to emphasise the need to find more effective means of increasing adherence—especially over the long term."
And they caution that a failure to take into account the typically poorer adherence to treatment in routine practice may serve to overestimate the benefits of preventive approaches based on drugs.