Tuesday, April 1, 2008

"Popular cholesterol drug fails to improve heart disease"

The above title was the headline on CNN yesterday, and is more than a little misleading. Certainly, if you own Schering or Merck shares, the ENHANCE(Ezetimibe and Simvastatin in Hypercholesterolemia Enhances Atherosclerosis Regression) results were basically a disaster... but if you are interested in the relationship between LDL cholesterol and cardiovascular disease then it's a bit more nuanced than that.

First, I'm not a doctor(MD or PhD), so nothing I'm about to write should be construed as medical advice or a voice of authority. However, this is kind of in my field, so I feel like I know something about how to interpret these results... at least better than your average headline writer.

Second, Vytorin didn't "fail to improve heart disease"(what does it mean to "improve" heart disease anyway?), it just didn't show additional improvement beyond a basic (and cheaper) statin. However, if you are on Vytorin it's not like you've been taking sugar pills... the statin component is still there and doing its job.

Third, the study measured carotid and femoral intima-media thickness, that is the vessel wall thickness of the carotid and femoral arteries, as their outcome variable. However, there is pretty weak relationship(R between 0.3 and 0.4) between carotid intima-media thickness and coronary artery disease (leading cause of death in the US). Now, the relationship is positive, so reducing carotid intima-media thickness is at least a good sign for coronary heart disease and a reduction in cardiac events but it's certainly nowhere even remotely close to a guarantee.

The science just doesn't appear to be there yet as to whether this drug is providing any additional help that a regular statin isn't... the ENHANCE study obviously isn't a good sign though... and I think it's a valid question as to why we still don't know after it's been on the market and prescribed like mad for 5 years.