Angry Doctor

Friday, March 02, 2007

To write is to sit in judgement on oneself

A thought-provoking post at Dr RW's blog today sends angry doc on a bit of introspection...

Long-time readers may remember that angry doc blogged about the issue of new guidelines on hypertension previously.

angry doc was brought up in the era of the 'J-curve': the concept that there exists a 'normal' range for blood pressure; go above or below that range, and your risk of mortality and morbidity increases correspondingly. But now that idea seems no longer valid, with studies concluding that there is 'no patient group among whom more intensive BP lowering would not be expected to produce greater risk reductions' and that '[t]hroughout middle and old age, usual blood pressure is strongly and directly related to vascular (and overall) mortality, without any evidence of a threshold down to at least 115/75 mm Hg'.

angry doc must confess to feeling discomfited by such studies, but it is unscientific to dismiss evidence without valid reasons as to why they are flawed, or without evidence that shows the contrary.

The point of this post, however, is not about what the 'healthy' range of blood pressure is, but that sense of discomfiture which reveals to angry doc his own prejudices: we all have our 'comfort zones' when it comes to health beliefs, and sometimes it can feel unpleasant when these beliefs are challenged.

But if angry doc is to practise what he preaches, he must assess the evidence presented and, if he can find no fault in them or evidence to the contrary, accept them and see how they should be applied in his practice.

As he has said, it is not a pleasant feeling, but nevertheless he finds comfort in a progressive system where evidence continues to be collected and studied, and change, when warranted, can be implemented.

Besides, he is pretty sure the 'J-curve' will be proven to be correct again some day... afterall, a blood pressure of 0/0mmHg can't be good for you!

2 Comments:

  • This quote below is from the following website, essays written by an English GP Malcolm Kendrick

    http://www.thincs.org/Malcolm.htm

    " I suppose that most people believe that it must have been proven by now that blood pressure lowering does reduce the rate of CHD, rendering the example of a high temperature somewhat pointless. Well, I am going to quote you quite a long passage from the European Heart Journal, issue 20, October 2000. Please read it carefully, for it is actually quite stunning.

    ‘It is widely believed that randomised trials have proved that lowering blood pressure is beneficial. Actually, that is not true. All antihypertensive drugs have profound effects on the cardiovascular system, aside from their haemodynamic (blood pressure lowering) effect. How much, if any, of the observed risk reduction can be ascribed to the reduction in pressure and how much to the direct action of the drug on the cardiovascular system? Motivated by the belief in the linear relationship of risk to pressure, many automatically attribute the risk reduction to the pressure reduction, ignoring the direct action of the drugs on the target outcomes. But results of a multitude of clinical trials make it clear that such a simplistic view cannot be true. In fact, evidence is mounting (especially from the newer trials) that it is the direct effects that are producing most, if not all, or the benefit and that the accompanying blood pressure reduction may be just an inconsequential side effect.’ Port S et al.

    In short, there is no evidence whatsoever that lowering blood pressure has any effect on CHD.



    I suppose that most people believe that it must have been proven by now that blood pressure lowering does reduce the rate of CHD, rendering the example of a high temperature somewhat pointless. Well, I am going to quote you quite a long passage from the European Heart Journal, issue 20, October 2000. Please read it carefully, for it is actually quite stunning.

    ‘It is widely believed that randomised trials have proved that lowering blood pressure is beneficial. Actually, that is not true. All antihypertensive drugs have profound effects on the cardiovascular system, aside from their haemodynamic (blood pressure lowering) effect. How much, if any, of the observed risk reduction can be ascribed to the reduction in pressure and how much to the direct action of the drug on the cardiovascular system? Motivated by the belief in the linear relationship of risk to pressure, many automatically attribute the risk reduction to the pressure reduction, ignoring the direct action of the drugs on the target outcomes. But results of a multitude of clinical trials make it clear that such a simplistic view cannot be true. In fact, evidence is mounting (especially from the newer trials) that it is the direct effects that are producing most, if not all, or the benefit and that the accompanying blood pressure reduction may be just an inconsequential side effect.’ Port S et al.

    In short, there is no evidence whatsoever that lowering blood pressure has any effect on CHD.



    I suppose that most people believe that it must have been proven by now that blood pressure lowering does reduce the rate of CHD, rendering the example of a high temperature somewhat pointless. Well, I am going to quote you quite a long passage from the European Heart Journal, issue 20, October 2000. Please read it carefully, for it is actually quite stunning.

    ‘It is widely believed that randomised trials have proved that lowering blood pressure is beneficial. Actually, that is not true. All antihypertensive drugs have profound effects on the cardiovascular system, aside from their haemodynamic (blood pressure lowering) effect. How much, if any, of the observed risk reduction can be ascribed to the reduction in pressure and how much to the direct action of the drug on the cardiovascular system? Motivated by the belief in the linear relationship of risk to pressure, many automatically attribute the risk reduction to the pressure reduction, ignoring the direct action of the drugs on the target outcomes. But results of a multitude of clinical trials make it clear that such a simplistic view cannot be true. In fact, evidence is mounting (especially from the newer trials) that it is the direct effects that are producing most, if not all, or the benefit and that the accompanying blood pressure reduction may be just an inconsequential side effect.’ Port S et al.

    In short, there is no evidence whatsoever that lowering blood pressure has any effect on CHD."

    By Anonymous Anonymous, At March 07, 2007 2:55 am  

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