Map of life expectancy at birth from Global Education Project.

Friday, March 09, 2007

More than you wanted to know about drug eluting stents

The hordes who have been hanging on every word of my jihad on behalf of open access scientific publishing will probably consider it good news that this week's NEJM is, in an unprecedented move, largely open access. Yup, you can read two "perspectives" pieces, three research reports, two meta-analyses, and an editorial, all on the subject of the relative long-term safety and efficacy of drug eluting vs. bare metal stents.

The bad news is, it's highly unlikely that you care enough about this subject to take advantage of this exciting, one-time offer. If you do care enough -- perhaps because you or a loved one are considering or have recently undergone a stenting procedure -- what you really need to know probably boils down to less than this avalanche of information. So I find this decision by the NEJM editors rather odd. Usually their weekly open-access piece is an analysis of a policy or ethical issue that does have much broader public interest, and is more accessible to a broad readership.

Anyway, since they obviously think this is a matter of urgent public importance, let me give you my take on it. Stents, for those of you who don't know, are metal devices in the form of what might be called cylindrical baskets - sort of like those novelty "Chinese" handcuffs made of reed - that are inserted into blocked coronary arteries and then expanded to let the blood flow freely. The Prince of Insufficient Light, "Crashcart" Dick Cheney, is the proud owner of two or three of them.

They work fine, but in the end, the plaque often regrows over the stents and the arteries close up again. So, some companies started manufacturing stents with coatings that release compounds which inhibit regrowth of the plaque. In clinical trials, they worked well, albeit only with 9 months of follow-up, so the FDA approved two such devices in 2003 and 2004, with the proviso that the companies follow patients for 5 years to make sure no problems cropped up.

Alas, a conference presentation in 2006 found that after 7-18 months, people with drug eluting stents had worse outcomes than people with plain metal stents -- higher rates of heart attacks and cardiac death. It seems the problem was that blood clots (as opposed to atherosclerotic plaque) were forming at a higher rate on the drug eluting stents. Other studies tended to confirm or contradict this finding.

After wading through all the conflicting and uncertain data, William Maisel in one of those free perspective articles basically concludes that the drug eluting stents are superior for the situations in which they were first tested -- people with "discrete, previously untreated lesions in native coronary vessels." The problem seems to be that doctors have been using them "off label," in situations such as people who have had heart attacks (I'm being sloppy with the vernacular, we're really talking about a specific kind of heart attack called an Acute Myocardial Infarction, but you don't care), in coronary artery bypass grafts, and in more complicated or serious kinds of blockages. It turns out that 60% of use has been off-label. In these situations, it appears, the drug-eluting stents are riskier.

So all you really needed was Dr. Maisel's article. This turns out to be a very clear example of a pervasive problem in medicine today. Drugs and devices are approved for specific uses in specific populations, based on trials that are limited to those circumstances. Then the manufacturers start selling them for all sorts of other purposes. Surprise, surprise! Bad things happen.

The law says that once a device or a drug is approved, doctors can use it off-label. The manufacturers aren't supposed to market it for off-label uses, but wink wink -- detailers can do so very easily, and subtly, and not get caught. Also, there's nothing illegal about manufacturers doing small, underpowered, short-term trials that appear to support off label use and then publicizing them -- even though they don't provide good enough evidence to get the products approved for those uses. And the manufacturers certainly don't discourage off-label use. There have been a couple of cases of manufacturers getting into trouble for off-label marketing, but they are rare. Another recent example of off-label prescribing which has gotten a lot of attention is giving powerful psych meds to children. That one happens to really outrage me, and I hope to write about it soon.

So here's just one more example of the pervasive corruption in the medical industry. The news you can use here is that if you have coronary artery disease and you are considering stenting, make damn sure your doctor is familiar with these studies and discusses them with you in light of your particular circumstances. Believe me, the FDA is not going to protect you.

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