I have been much cheered by all the discussion on my series about what caused heart disease a.k.a. cardiovascular disease. Because of various comments, my series has gone off in a few different directions. I realise that not everyone agrees with everything (or anything?) I have to say, and that several issues I thought were clear, clearly are not. This is fine. Science should progress by discussion and debate and contradictions.
In this blog, in order to answer some of what people have written (albeit indirectly), I am going to look at two of the conventional risk factors for CVD in a bit more detail, and try to explain why they represent a major problem for conventional thinking.
As many of you may have discovered, if you go to see your GP – almost anywhere in the world – they will use a list of ‘standard’ risk factors to calculate your risk of a cardiovascular ‘event’ over the next five or ten years.
There are a few of these calculators, but two of most commonly used are probably QRISK2 and the ASCVD, created by the American College of Cardiology and American Heart Association. [ASCVD = atherosclerotic cardiovascular disease]. I cannot find out where the term QRISK comes from – perhaps someone can help me.
The ASCVD is a bit shorter than QRISK. It looks at:
- Total Cholesterol
- Systolic blood pressure
- Diastolic blood pressure
- Treatment for blood pressure
The QRISK is a UK developed risk calculator. It is a bit bigger and more complicated than ASCVD. It looks at:
- Systolic blood pressure
- Diastolic blood pressure
- Total Cholesterol
- Total Cholesterol/HDL ratio
- Serum triglyceride
- Glucose Impaired glucose tolerance/diabetes
- Left Ventricular hypertrophy
- Central obesity
- South Asian (South Asians, in the UK, have a far higher risk of CVD)
- Family history of CVD
Now, there is no doubt that all of the factors on both lists are associated with CVD – to a greater or lesser degree. At least they are for the US and UK population currently living. It has to be pointed out thought, that if you use QRISK in France, you have to divide the risk by 4… ahem, slight problem.
A further problem is that it has been discovered that they both vastly over-estimate risk in US and UK population.
‘A widely recommended risk calculator for predicting a person’s chance of experiencing a cardiovascular disease event — such as heart attack, ischemic stroke or dying from coronary artery disease — has been found to substantially overestimate the actual five-year risk in adults overall and across all sociodemographic subgroups. The study by Kaiser Permanente was published today in the Journal of the American College of Cardiology.
The actual incidence of atherosclerotic cardiovascular disease events over five years was substantially lower than the predicted risk in each category of the ACC/AHA Pooled Cohort equation:
- For predicted risk less than 2.5 percent, actual incidence was 0.2 percent
- For predicted risk between 2.5 and 3.74 percent, actual incidence was 0.65 percent
- For predicted risk between 3.75 and 4.99 percent, actual incidence was 0.9 percent
- For predicted risk equal to or greater than 5 percent, actual incidence was 1.85 percent
“From a relative standpoint, the overestimation is approximately five- to six-fold,” explained Dr. Go. “Translating this, it would mean that we would be over-treating a good many people based on the risk calculator.”’1
So, you feed your risk factors in a risk calculator that took many years to create, using data carefully gathered by experts from the world of cardiology, and your true risk is overestimated five to six fold. Excellent. That mean millions upon millions of people have been told to take a statin based on a calculation that is so inaccurate as to be virtually meaningless. [This was always going to happen, because risk was established using clinical data from decades ago, since when, CVD rates have fallen dramatically]
Anyway, leaving the horrible inaccuracy of these risk factor calculators aside for the moment. What of the risk factors themselves? I am not going to look at all of them here, just two. Firstly, age. There is no doubt that age is the single most important risk for CVD. Your risk at 65 is around ten times as high as at age 35 – no matter what the overall risk may be in your particular country.
In fact, if you have no other factors at all, in the US, your future CVD risk at the age of 67 is so high (according to the calculator) it means that you are advised to go on a statin immediately, for the rest of your life. Ho hum. For women it is a few years later. ‘Here’s your first pension payment – with built in statin prescription.’
I find it fascinating that almost everyone seems to accept age as a risk factor for CVD, without really questioning why this should be so. Age does not necessarily increase the risk of diseases. There are many which are more common when you are younger, and the risk diminishes as you age.
The argument seems to be that CVD slowly progresses. Thus, as you get older, the risk increases. Yes, perhaps. However, if you have no conventional risk factors for CVD, why should it progress at all? At the risk of repeating myself, I shall repeat myself. You have no risk factors for CVD. Yet, as you grow older, your risk of CVD reaches the point where you are statinated. Because your future risk is so high.
But what is causing the atherosclerosis in your arteries to develop. Age? Through what process can age created atherosclerotic plaques, assuming no other risk factors? Raised cholesterol… well you don’t have raised cholesterol. Raised BP? Well, you don’t have raised BP. Smoking, well, you don’t smoke… etc.
The other major risk factor where we have an acceptance of a fact – without even an attempt at explanation is gender. In most populations younger men have a far higher risk of CVD than women. The different in risk varies greatly, but averages at about three to one. By which I mean, a women aged 55 women will have around one third the risk of a man aged 55 (living in the same country). Even if they have exactly the same risk factors.
For years it was stated, with great confidence, that this difference was due to female sex hormones. These hormones in some – never fully stated fashion – protected women against CVD. It has now been proven, beyond a molecule of doubt, that this is not true. Female sex hormones do not protect against CVD. Indeed, they probably accelerate it.
So, what does protect women against CVD. There is no explanation. It just is. Feed gender into the calculator and a different risk pops out for men and women. Why, because men and women, have a different risk of CVD. Why? Because they do. [BTW, the South Asian issue is much the same. Multiply the risk by 1.4. Why, because you do].
The reality is that age, and gender, are two of the most powerful risk factors for CVD. In that, if you use the ASCVD or QRISK calculator and change only age, and gender, the risk will go from close to zero, in a young woman to dark red – danger, danger, in an older man. Even if you set all other risk factors to zero.
It has always baffled me that experts in cardiology seem utterly unconcerned about this. They do not even consider that this is an issue. However, if the two most powerful risk factors you have for CVD, cannot be explained, are not explained, then you really have a major problem. Even if you cannot even comprehend that you do.
If you cannot explain why age, and gender, cause CVD… you cannot explain CVD.