Ezetimibe is an effective cholesterol-reducing drug (it works by blocking cholesterol absorption from the gut). I came across a study this week from a group of researchers based in Michigan in the US which concluded that ezetimibe appeared to have a ‘protective effect on major AD [atherosclerotic disease] events and all-cause mortality…’ . In other words, the authors were suggesting that ezetimibe can reduce the risk of heart attacks, strokes and overall risk of death. I have to admit, I was somewhat surprised by this conclusion, because I was not aware of any good evidence that supports it.
Actually, in trials, ezetimibe has not performed well at all. Not one single study has shown it to have benefits for health. In fact, in one study, there was evidence that it might actually worsen the development of atherosclerosis (the narrowing process in the lining of the arteries). And other evidence shows that the drug can increase the risk of death from cancer.
So, how were the paper’s authors able to put such a positive spin on these results? The answer was to essentially ignore these results, and ‘analyse’ the data is a completely different way. The paper in question is based on what is known as ‘epidemiological’ evidence. This sort of study looks at associations between things. In this study, the health outcomes in people taking ezetimibe and those not taking ezetimibe were compared. Those taking ezetimibe were found to have better outcomes, hence the study’s conclusions.
However, while epidemiological evidence may find associations between things, that does not mean that one thing is causing the other. So, while ezetimibe use and better health outcomes are linked, that does not mean the drug is causing those better outcomes.
It is possible, for instance, that individuals taking ezetimibe may be generally healthier than those not taking it, because they may be more health-conscious and more likely to seek medications they believe will benefit them. Also, sicker individuals may be less likely to be prescribed medication because of fear of side-effects or drug interactions. What this means is that the health benefits linked with ezetimibe may have nothing to do with ezetimibe itself, and everything to do with the general characteristics of people who take this drug.
To really know for sure whether ezetimibe is beneficial to health, we require clinical studies in which ezetimibe is tested against a dummy drug (placebo). But, as we already know (see above) we have no positive studies of this nature. And where ezetimibe has been added in with a statin drug, no added benefits have been found, and in fact some evidence shows worse outcomes.
In short, we have no evidence at all the ezetimibe benefits health, and at least some that suggests it is harmful to health. These are the facts we have based on the best available clinical evidence.
The authors of this recent paper do seem to have effectively junked the best and most reliable evidence we have, in favour of notoriously unreliable epidemiological research. This is another example of what appears to be a desperate attempt by some researchers to attach a benefit to a drug which evidence shows does just not exist in reality.
1. Hayek S, et al. Effect of Ezetimibe on Major Atherosclerotic Disease Events and All-Cause
Mortality. Am J Cardiol. 2012 Dec 4 [Epub ahead of print]