Good and Bad News for Reducing Heart Attack Deaths
Good and bad news often go together, for what is good news for some is bad for others. Shareholders in pharmaceutical companies that produce statins will have been heartened (no pun intended) by a paper in a recent edition of the New England Journal of Medicine in which the authors calculated that, under the new guidelines of the American College of Cardiology and the American Heart Association with regard to lipid levels in the blood, 12.8 million more adults in the United States alone would be "eligible" for (i.e. ought ideally to have) treatment with statins. In fact, very nearly half the population older than 40 ought to take them, and seven eighths of the population over 60. As a man over sixty who never has any blood tests done, my heart sinks (again no pun intended). We are all guilty of illness until proven healthy: not good news.
The authors compared the therapeutic consequences of the old guidelines with the new. In effect the new guidelines lowered the threshold for treatment. According to these guidelines, anyone over 40 with known cardiovascular disease should receive statins, irrespective of their level of Low Density Lipoprotein (LDL); while anyone with a level of 70 milligrams per decilitre or more and who has diabetes or a statistical risk of a heart attack of more than 7.5 percent within the next ten years should also receive them.
Taking a rather small sample of adults over 40 from the National Health and Nutrition Examination Survey whose blood lipids were measured and extrapolating it to the U.S. population as a whole, the authors conclude that, if the new guidelines were put into practice rather than the old, 14.4 million adults in the U.S. who would not have been "eligible" for treatment under the old guidelines would now be "eligible" for it, while 1.6 million who would have been "eligible" under the old guidelines would no longer be "eligible."
The authors try to work out the annual health benefits if everyone took the tablets just as the doctor ordered (about as realistic a prospect as pure communism or a return to seventh century Arabia). They calculate that about 475,000 cardiovascular events – heart attacks and strokes – would be avoided, more than 90 percent of them among people of 60 years or more. In effect, a third of all the 40 - 60 year olds, some 25,000,000 people, in the United States would be taking statins in order to avoid fewer than 47,500 cardiovascular events annually.
In the real world, of course, compliance with statin treatment would be much less than perfect. Some studies suggest that a half of all those prescribed statins have stopped taking them by 12 months. The benefits of statin therapy under everyday conditions, then, are far less than those calculated as if we lived in a perfect world. It is not only political or economic theorists who are inclined to utopianism.
The authors discuss some of the limitations of their study. They concede, for example, that the sample by which they estimated the pattern of LDL distribution in the American population might not have been representative, and if it were not their calculations would be inaccurate. But there is one limitation they do not mention, and that is that there is a very marked secular trend in the numbers of "cardiovascular" events. In 1963, the age-adjusted annual death rates from cardiovascular disease in the United States were 805 per 100,000 of the population; in 1990, 413; in 2011, 236. The rate of deaths from heart attacks had gone down by more than three quarters. If this trend continues (but projections are not predictions), statins will become redundant, their supposed benefits nugatory.