Map of life expectancy at birth from Global Education Project.

Tuesday, March 27, 2007

Another Open Door Crashed Through

No doubt you have encountered all the flapdoodle over the new findings that angioplasty and stenting in coronary arteries does not prevent heart attacks or reduce the risk of death. (Authorship by a multitude. This does not apply to people who have an acute blockage of a coronary artery, for whom an immediate roto-rooter intervention to reopen the blocked artery is indeed beneficial.) This news immediately caused the stock of Boston Scientific, which manufactures stents, to dive.

But, uhh, this is not exactly unexpected, or even news. There has never been any evidence that angioplasty and stenting as a prophylatic strategy can prevent heart attacks or prolong life. The only justification for these interventions in people who are not already having an acute heart attack is to relieve symptoms of angina. (Ditto for coronary artery bypass graft surgery.) What is new, if anything, about this study is that it finds that even those benefits are very modest.

Nevertheless, there has been a sort of vague impression out there among the public, and evidently many doctors, that these procedures do have preventive value. I can't cite chapter and verse on that, but the vast excitement that greets this study is proof of it. As the authors state right up front, with a veritable torrent of foonotes:

PCI reduces the incidence of death and myocardial infarction in patients who present with acute coronary syndromes,5,6,7,8,9,10 but similar benefit has not been shown in patients with stable coronary artery disease.11,12,13,14,15 This issue has been studied in fewer than 3000 patients,16 many of whom were treated before the widespread use of intracoronary stents and current standards of medical management.17,18,19,20,21,22,23,24,25,26,27,28

Although successful PCI of flow-limiting stenoses might be expected to reduce the rate of death, myocardial infarction, and hospitalization for acute coronary syndromes, previous studies have shown only that PCI decreases the frequency of angina and improves short-term exercise performance.11,12,15 Thus, the long-term prognostic effect of PCI on cardiovascular events in patients with stable coronary artery disease remains uncertain.

So, hundreds of thousands of people have undergone these procedures largely on the basis of speculation. I think this is a very powerful example of the interventionist bias in American medicine. We fear that a government financed, single-payer system will mean that health care needs to be "rationed," but the fact is, that will be a good thing. The compulsion we feel to "do something" is very likely to lead us to do more harm than good.

Of course, in the case of coronary artery disease there is a good deal we can and should do, both for prevention and treatment. Number one, do that boring stuff that doesn't make money for any Fortune 500 company, that is lose weight, eat right, exercise more, quit smoking. Number two, there are medications that are beneficial under the right circumstances, but for the most part, they are available as inexpensive generics. (Please ignore the whorish Dr. Jarvik in those slick TV ads, trying to sell you an expensive patented statin.) But it isn't nearly as exciting, or profitable.

No comments: