Last Friday saw the publication of an intriguing study which assessed the relationship between cholesterol levels and ‘vascular’ mortality ” namely deaths due to heart disease and stroke. This review appeared in the Lancet medical journal, and assessed data from 61 studies. In short, this piece of research found that higher levels of cholesterol were associated with an increased risk of death due to ‘ischaemic heart disease’, but this was not the case with stroke. This finding is, to my mind, highly significant, and here’s why.
Conventional medical thinking is that high levels of cholesterol in the blood stream cause ‘atherosclerosis’ ” a furring up of the arteries through the build of fatty deposits there. Atherosclerosis is believed to be the underlying process in pretty much all heart attacks, and about 85 per cent of strokes (15 per cent of strokes are caused by bleeding rather than vessel blockage). Logic would dictate that the if cholesterol causes atherosclerosis, then higher levels of cholesterol should increase the risk of both heart disease and stroke deaths.
The fact that this appears not to be the case appears to have left the researchers who unearthed this data a little nonplussed. The authors, collectively referred to as the ‘Prospective Studies Collaboration’ say that their findings are ‘unexplained’ and ‘invite further research’. They are also in their paper keen, it seems, to remind everyone that cholesterol reducing drugs (statins) reduce the risk of stroke (and heart disease).
So, what’s going on here? Well, just applying a simple deduction for a moment, if strokes are not caused by raised cholesterol, but statin drugs (which reduce cholesterol) reduce risk, is it not possible that statins reduce stroke risk through a mechanism other than cholesterol reduction. Before anyone starts nominating me for a Nobel prize, can I just point out that is well established that statins have a number of effects in the body, which include a blood-thinning effect. Just this effect alone would be expected to reduce the risk of stroke.
What is puzzling about the Lancet paper is that the effects of statin drugs other than cholesterol reduction are not even mentioned. The Prospective Studies Collaboration, by the way, is made up more than 100 doctors and scientists, all of whom had the opportunity to contribute to the interpretation of the results. It is almost beyond comprehension, to me anyway, that none of them thought of suggesting that the paradoxical findings regarding stroke could be explained by the fact that statins are perhaps working though mechanisms other than cholesterol reduction.
To do that, of course, would ask serious questions about the whole cholesterol hypothesis. And one might imagine that drugs companies who make money though the promotion of this concept as well through the sale of ‘solutions’ to the cholesterol ‘problem’ would be none too keen about this.
So, is it possible that drug company money might have exerted some influence here? The Lancet paper was written by a ‘writing committee’, comprised of 9 individuals, all but one of whom are members of what is known as the ‘Clinical Trial Service Unit’ (CTSU). In the ‘Conflict of interest statement’ at the bottom of the paper it is revealed that the CTSU is involved in clinical trials of cholesterol lowering medication and is funded, at least in part, by manufacturers of that medication including Merck, Schering and Solvay. Oh, and the one member of the writing committee who not a member of the CTSU has shares in GlaxoSmithKline (another manufacturer of cholesterol lowering medication).
None of this proves anything of course. However, bearing in mind that the CTSU is involved in research into statin drugs, does it not seem a little odd that its members seem to be unaware of the effects that these drugs can have in the body other than cholesterol-reduction? It does to me.
References:
1. Prospective Studies Collaboration. Blood cholesterol and vascular mortality by age, sex, and blood pressure: a meta-analysis of individual data from 61 prospective studies with 33000 vascular deaths. Lancet 2007;370:1829-1839.
