Preventive cardiology: talking it through
Authors: R. Fox
Journal: Journal of the Royal Society of Medicine (2003)

The past decade has seen wonderful progress in clinical cardiology—not least the advent of statins, with their 20-30% reduction of the rate of heart attacks in those at high risk. Yet, when some new agent comes along there are always voices that say, ‘why the excitement over this drug when we are underprescribing the agents already proven to work’? In survivors of myocardial infarction (MI), the low use of protective drugs observed in many different countries has been condemned as a ‘collective failure of medical practice’1. But is it? Although in population terms these treatments can make a big difference, the promised benefits are less impressive when expressed in terms of benefits to the individual. Take the 30% reduction in relative risk of coronary events achieved by pravastatin in hypercholesterolaemic men: this consisted of a 2.3% reduction of absolute risk over 4.9 years (risk without treatment, 7.9%)2. Even high-risk individuals have a less than 5% chance of benefiting from a statin taken for 5 years. If the proposed drug has troublesome side-effects (a beta-blocker, for instance), pharmacoprevention becomes notably less attractive.

Trewby and co-workers3, from Darlington, have sought opinions on the reductions in absolute risk of heart attack that might persuade people to take a drug for the rest of their lives. They questioned three groups with about a hundred in each—group 1 just out of coronary care units, group 2 who had not had a recent MI but were taking cardioprotective drugs, and group 3 who had not had an MI and were not taking drugs. Each person was asked, supposing that you had a high cholesterol and were offered lifelong drug therapy that could safely lessen your risk of heart attack, what level of protection would make this worth while? An ingenious visual analogue scale helped them decide. The answers in these three groups suggested that the most powerful drugs such as statins fall a long way short of the performance expected and desired, even by people who have already had a heart attack. A drug that offered 5% or less benefit over 5 years would be acceptable to just 32% of group 1, 29% of group 2 and 21% of group 3. These figures would, however, rise to 69%, 74% and 56% if the drug was recommended by the doctor.

The UK National Service Framework for Coronary Disease proposes use of cardioprotective drugs for all individuals whose risk of MI exceeds 30% in 10 years4. Trewby and co-workers reckon that, over that period, at most 1 in 10 such patients will benefit from a statin—a level of protection that would prompt acceptance in 45% of their group 1, who had already experienced an MI, and only 28% of their group 3, who had not. In other words, there is a clash between the priorities of individuals—many of whom dislike the idea of taking drugs for life—and the aspirations of public health. Trewby et al. conclude: ‘Doctors, as treatment brokers, must inform their patients of the quite small percentage chance that they will benefit from preventive drugs... and take their views into account when prescribing, even if this leads to a decrease in uptake of preventive drugs in the community’. The dilemma posed by these researchers was, of course, far removed from the typical consultation in primary care. For instance, a risk factor will seldom be looked at in isolation; moreover, for many people the chief concern is not a heart attack but the threat of chronic morbidity—angina or heart failure or the dreaded stroke. In an accompanying commentary written just before his death, Sir Douglas Black5 counsels against the rigid application of guidelines but also doubts the need to hand out quantitative information routinely, as recommended by Trewby.

With the National Service Framework for Coronary Disease we are very likely to see an increase in prescriptions for cardioprotective agents. The real challenge is to avoid high subsequent drop-out. For long-term adherence, the best policy for clinicians may be the one proposed by Sir Douglas: address the patient's worries. It is noteworthy that, in the Trewby study, doctors' recommendations would have doubled the proportion saying yes.