Tag Archives: Coronary Heart Disease

Proving that black is white

Last week I was going through some old files, and presentations, in a vague effort to clean up my computer. Whilst looking a one of many thousands of studies I had filed away I came across this paper: ‘Clarifying the direct relation between total cholesterol levels and death from coronary heart disease in older persons1.’

I read it, and immediately recalled why I kept it. For it came to the following, final, conclusion:

 ‘Elevated total cholesterol level is a risk factor for death from coronary heart disease in older adults.’

I remember when I first read this paper a few years ago. My initial thought was to doubt that it could be true. Most of the evidence I had seen strongly suggested that, in the elderly, a high cholesterol level was actually protective against Coronary Heart Disease (CHD).

However, when a bunch of investigators state unequivocally that elevated cholesterol is a risk factor for heart disease, I try to give them the benefit of the doubt. So I read the damned thing. Always a potentially dangerous waste of precious brainpower.

Now, I am not going to dissect all the data in detail here, but one sentence that jumped out of the paper was the following:

‘Persons (Over 65) with the lowest total cholesterol levels ≤4.15 mmol/L had the highest rate of death from coronary heart disease, whereas those with elevated total cholesterol levels ≥ or = 6.20 mmol/L seemed to have a lower risk for death from coronary heart disease. ‘

Now, I can hardly blame you if you struggled to fit those two quotes together. On one hand, the conclusion of the paper was that .. ‘Elevated total cholesterol level is a risk factor for death from coronary heart disease in older adults.’ On the other hand, the authors reported that those with the lowest total cholesterol levels had the highest rate of CHD; whilst those with the highest cholesterol levels had the lowest rate of CHD.

Taken at face value, this paper seems to be contradicting itself…. utterly. However, the key word here, as you may have already noted, is seemed. As in… those with elevated total cholesterol levels ≥ or = 6.20 mmol/L seemed to have a lower risk for death from coronary heart disease. ‘

Now you may think that this is a strange word to use in a scientific paper. Surely those with elevated total cholesterol levels either did, or did not, have a lower risk of death from CHD? Dying is not really something you can fake, and once a cause of death has been recorded it cannot be changed at a later date. So how can someone seem to die of something – yet not die of it?

The answer is that you take the bare statistics, then you stretch them and bend them until you get the answer you want. Firstly, you adjust your figures for established risk factors for coronary heart disease – which may be justified (or may not be). Then you adjust for markers of poor health – which most certainly is not justified – as you have no idea if you are looking at cause, effect, or association.

Then, when this doesn’t provide the answer you want, you exclude a whole bunch of deaths, for reasons that are complete nonsense. I quote:

‘After adjustment for established risk factors for coronary heart disease and markers of poor health and exclusion of 44 deaths from coronary heart disease that occurred within the first year, (my bold text) elevated total cholesterol levels predicted increased risk for death from coronary heart disease, and the risk for death from coronary heart disease decreased as cholesterol levels decreased.’

Why did they exclude 44 deaths within the first year?  Well, they decided that having a low cholesterol levels was a marker for poor health, and so it was the poor health that killed them within the first year.

The reason why they believed they could do this is that, a number of years ago, a man called Iribarren decreed that the raised mortality always seen in those with low cholesterol levels is because people with low cholesterol have underlying diseases. And it is these underlying diseases that kill them. (What, even dying from CHD. And how, exactly does CHD cause a low cholesterol levels….one might ask).

In truth, there has never been a scrap of evidence to support Iribarren’s made-up ad-hoc hypothesis. [A bottle of champagne for anyone who can find any evidence]. However, it is now so widely believed to be true, that no-one questions it.

Anyway, without chasing down too many completely made-up ad-hoc hypotheses, the bottom line is that this paper stands a perfect example of how you can take a result you don’t like and turn it through one hundred and eighty degrees. At which point you have a conclusion that you do like.

Young researcher: (Bright and innocent)  ‘Look, this is really interesting, elderly people with low cholesterol levels are at greater risk of dying of heart disease.’

Professor: (Smoothly threatening) ‘I think you will find…. if you were to look more carefully, that this is not what you actually found….. Is it? By the way, how is your latest grant application going?’

Young researcher: (Flushing red at realising his blunder) ‘Yes, by golly, how silly of me. I think I really found that elderly people with high cholesterol levels are at a greater risk of dying of heart disease.’

Professor: ‘Yes, excellent. Be a good lad, find a good statistician to make sure the figures make sense, and write it up.’

For those who wonder at my almost absolute cynicism with regard to the current state of Evidence Based Medicine, I offer this paper as a further example of the way that facts are beaten into submission until they fit with current medical scientific dogma.

As a final sign off I would advise that any paper that has the word ‘clarifying’ in its title, should be treated with the utmost suspicion. I think George Orwell would know exactly what the word clarifying means in this context. Facts do not need clarification.

 

1: Corti MC et al: Clarifying the direct relation between total cholesterol levels and death from coronary heart disease in older persons. Ann Intern Med. 1997 May 15;126(10):753-60

A simple Question – that opens a can of worms

A day or so ago I received this e-mail from a doctor in London.

Dear Dr Kendrick,

I work as a GP in Wandsworth London and I read that you don’t
believe that much in cholesterol and CHD.

I do agree up to 50% of MI patients have normal cholesterol
but some say what’s normal for UK is actually high. Is this argument valid?

Best wishes

Define ‘normal.’ Does normal mean average? If we took the average height of everyone in the UK we would find (very nearly) that 50% of those dying of CHD (coronary heart disease) were above average height and 50% below. So average is clearly normal, but then again so is being tall, or short.

However, if we decided that average height of everyone living in the UK was above ‘normal’, and we then lowered the definition of ‘normal height’ by three inches, we would find that the vast majority of people dying of CHD were now above average height. At which point we could decree that being taller than normal was a risk factor for CHD.

This would obviously be a completely bonkers thing to do. Yet, you can do it with cholesterol levels and everyone nods in general agreement.

Aha, but the argument goes that our lives are completely different than the lives of our ancestors, which has caused our cholesterol levels to be unnaturally high.

An article in the Journal of the American College of Cardiology best summed up this line of thinking. Under the heading ‘Why average is not normal’, O’Keefe, the lead author, made the claim that: ‘Atherosclerosis is endemic in our population, in part because the average LDL (“bad” cholesterol) level is approximately twice the normal physiologic level.’ In short, according to O’Keefe, our cholesterol level should be about 2.5mmol/l, not 5.2mmol/l.

He based his argument, in part on looking at the cholesterol levels of various animals e.g. elephants, and boars, and suchlike. He also used the argument that very young babies (neonates) have cholesterol level of about 2.5mmol/l. Now, in my opinion, anyone proposing this argument should have their medication increased. We should base our cholesterol levels on those found in other animals species….yes, of course we should. You mean those animal species with an average life expectancy of ten years, for example.

However, this argument is now pretty widely accepted by the medical community. We are all, everyone, living in the West, living in such an ‘unhealthy’ way that our cholesterol levels are unnaturally high. The true normal cholesterol levels is 2.5mmol/l.

Fine, if we re-set normal at 2.5mmol/l we will find that 99% of people dying of heart disease do have a ‘high ‘cholesterol level. Problem sorted, average is no longer normal, and the hypothesis that a high cholesterol level is a risk factor for heart disease is now true.

Hold on, I’ve got an idea…