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"Normal" Population Abnormalities Versus Risk FactorsProfessor Andrew Wilson, RMA Member Paper prepared from edited transcripts of the RMA Forum "Normal" Population Abnormalities Versus Risk FactorsWhen does something which is basically fairly normal for our society become something which is abnormal? This issue goes back quite a long way, and perhaps the easiest way to look at it is to take the example of blood pressure. When people first started to think about high blood pressure as being a medical problem, back in the pre-60s days, there was a thing called "malignant hypertension", which was a disease in which the blood pressure was very high. These people had systolic blood pressures which were over the two hundreds, which was frequently rapidly fatal. People would have strokes or renal failure within years of the development of this condition. There were medications that were available to treat it, but they were very limited in terms of what they could do, and they had quite serious side-effects. Over time various studies started to point to the fact that you didn't have to have malignant hypertension, but having high blood pressure which was something less than that malignant hypertension also placed you at increased risk of heart disease, stroke and renal disease. The development of new medications which didn't have quite the same side-effect profile meant that people with high blood pressure could be treated at a lower level. The level at which we've been prepared to treat high blood pressure, the level which is called hypertension, has progressively decreased, and we now accept a level of around 120 systolic as being a level above which we think somebody has hypertension. We now know from studies of over a million people, studies from countries all around the world, China, Australia, the UK, US and Europe, that even as you go below those levels that we call hypertension, people who have higher levels of blood pressure have a higher risk of stroke and heart attack than people who have lower levels of blood pressure. However, there is still only one group that we're calling hypertensive, that is those people whose blood pressure is above this magic mark of 120, which is the point when we start to treat it. A similar problem exists in relation to blood lipids, or cholesterol levels. I am part of a committee which is being convened for the third time in 10 years to look at what levels of blood cholesterol we should treat with drugs. Progressively over that 10 year period we have seen a lowering of the threshold as we started to understand that lower levels of cholesterol seem to be associated with increased protection from heart disease and stroke. One in seven dollars of a budget of about $7 billion for the Pharmaceutical Benefits Scheme in Australia now goes towards supporting cholesterol lowering therapy. What is more, the most recent data suggests that you can treat people down to a level of at least 3.5 and probably even get people's cholesterols down to a level of about 2.7, and they'll still gain some benefit for it. Now, if we look in the Australian population there's virtually nobody who has a cholesterol level of 3.5 or lower. It's the exceptional person, perhaps elite athletes or SAS serving members, who would have cholesterol level which might get down that low, and even many of them will have levels which are higher than that. So, we're going to have to make a decision - do we give everybody in Australia cholesterol lowering therapy? Do we consider that everybody has an abnormal cholesterol as the case may be? Clearly, as a society, that's a fairly significant issue that we're going to have to come to grips with. That brings me on to the last item that I want to talk about, and that's weight. In the Australian population weight is increasing. It increases with age across the population, and it's unfortunate that we are now also seeing an epidemic of obesity in young children. What do we mean by obesity? There is one set of definitions which have come out from the World Health Organisation which state that a BMI of 25 to 29 will be called overweight and a BMI of 30 or over will be called obese. In and of itself being overweight or obese is not unhealthy. I don't consider myself to be sick just because I carry an extra 10 kilos of weight. I will start to think of myself as sick if I develop some complications as a result of that, and I'd probably think of myself as sick if I was mad enough to let somebody try and treat that in some way. The difficulty that the RMA is facing in trying to deal with this is that by the basis of our legislation we are required to make SOPs for diseases. How do we handle these things which are almost normal patterns in our community and how do we try and think about the association between that and some exposure that may or may not have occurred during service? That's a challenge, and it's one that we're going to have to continually keep under review. We've tended to take a view that if a doctor diagnoses it as a treatable problem or if there is some complication, then we'll call it a disease. Some examples are hypertension and sliding hiatus hernia. Will it stop there? Is it going to stop with weight? Is that the last thing that we're going to have to look at? No, there are other things that are already here that we're going to have to consider in the same way. Another issue that we're going to have to consider, for instance, is low bone density or osteoporosis. Osteoporosis is a disease defined by reaching a certain threshold of bone density, much in the same way as hypertension. There's a lot of argument going on in the medical community about the cut-off point at which we define osteoporosis. It is being argued that perhaps it is too high. Again, we are dealing with a condition which will affect virtually all women once they become post-menopausal, and which is increasingly being recognised as a common problem for men, particularly as men survive longer. Although we don't necessarily have any answers, we felt we needed to discuss these issues, to try and give you an idea of the type of thinking that we have to go through. As a society we are trying to face this problem which is in almost plague-like proportions, but which is not easily understood in the traditional way that we think about disease and abnormality physiologically. Thank you very much.
This page last updated 22 March 2005. |
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