Friday, June 24, 2005

Everybody hurts

'One in four unaware of high blood pressure', declared the Daily Mail on 15 June, reporting on research from the charity Stroke UK which suggests that millions of people have high blood pressure but are unaware of it. According to the charity's press release, 'High blood pressure causes 40 per cent of strokes and is a main contributor to heart disease in the UK'. But high blood pressure is not the only 'silent killer' we need to look out for. The Daily Mail reported on 'The UK's cholesterol crisis' in February 2005, in response to news that half of British adults had levels of 'the hidden killer which clogs the arteries and causes heart disease' that were too high.

In fact, news items and health agencies are constantly telling us to watch our blood pressure and cholesterol readings. Blood pressure monitors and cholesterol testing kits are now widely available to the public. Some cholesterol-lowering drugs can now be bought without prescription, despite concern about side effects. Professor Nicholas Wald, among others, has suggested that a multi-drug pill be given widely to those over 55 years old. The aim of this 'polypill' would be, among other things, to reduce blood pressure and cholesterol.

In 2003, the World Health Organisation issued guidelines on the prevention of cardiovascular disease - suggesting blood pressure above 140/90 millimetres of mercury (mmHg), with no age correction, and serum cholesterol of 5 millimoles per litre (mmol/l) as the appropriate thresholds for intervention. It is on this basis that many of the most alarming stories have emerged. Yet these thresholds may be including so many people in the 'at risk' category as to make it meaningless, unhelpful and potentially dangerous.

An editorial in this week's British Medical Journal by Steinar Westin and Iona Heath draws out some of the consequences of these guideline changes. Using figures from Norway's Nord Tröndelag health survey, the authors note that a startlingly high number of people are now effectively defined as 'sick'. The combination of the two guidelines meant that, in the Norwegian sample, 90 per cent of those aged 49 and above would exceed one or both of the guideline levels. Even at the age of 24, over half the population would be considered at risk.

While treating very high blood pressure and cholesterol with drugs has been shown to be effective, those benefits are greatly reduced for people with lower readings. However, the rate of side effects for these drugs remains unchanged. Thus, more people are being treated with less hope of benefit, while increasing the number of those who could suffer adverse reactions to the medication. Nor is there enough evidence, say the authors, about the long-term effectiveness of these treatments, particularly when a number of drugs are used in combination to treat different conditions. At best, this is a waste of valuable resources. At worst, it could be doing more harm than good.

Moreover, little work has been done on the effect of telling people who have no symptoms, and quite probably no disease, that they are in fact 'at risk'. Patients are frequently asked to make substantial changes to their diet and activity in the hope of reducing their readings. Is the additional anxiety and the limitations patients will put on their lifestyles really worth it? This isn't the only example of guideline slippage in recent years. Changes in the definition of 'overweight' and 'obese' now mean that roughly two-thirds of the UK population is designated as overweight - again, with little apparent benefit in terms of health.

All of this is happening at a time when life expectancies are at an all-time high and are continuing to rise. While we've never been healthier, the health authorities are doing their best to turn us into a society of over-medicated hypochondriacs.

Read: Thresholds for normal blood pressure and serum cholesterol, British Medical Journal, 25 June 2005

spiked-central | Panic | Don't panic

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