What is the best way to teach epidemiology?
Epidemiology and evidence-based medicine (EBM) are, broadly speaking, about giving people the skills to evaluate and to produce evidence which can help to make clinical decisions. Many people can make use of those skills: EBM-enthusiasts, epidemiologists, physicians, surgeons, non-clinicians, patients, journalists and policymakers to name a few. However, the best way to teach those skills to the people who need them most is still elusive. Such skills are crucial if clinicians are to keep up-to-date in the rapidly evolving world of medicine.
This week I am attending the 42nd Ten Day Teaching Seminar in Cardiovascular Disease Epidemiology and Prevention, organised by the World Heart Federation in Hyderabad. Since 1968, these seminars have been occurring annually to provide basic epidemiology training to health professionals from all over the world, but particularly focussing on developing country participants, in an effort to build research capacity. Since 1973, a parallel 10-day seminar has been running in the USA. Together, these workshops have helped to train over 1000 delegates, many of whom have become leaders in cardiovascular research. The Centre for EBM in Oxford has been running workshops for both teachers and students of EBM since the mid-1990s. The combination of taught material, group work and networking with other participants seem to make these short workshops the ideal way to both teach and inspire people to use these skills in their every-day practice.
India is at the epicentre of the growing global burden of stroke and coronary heart disease and the world is watching how it deals with its burgeoning epidemic. One of the many challenges is to train the next generation of researchers and clinicians and to build up adequate infrastructure to tackle the problem locally. Currently, many Indians are travelling to schools of medicine or public health in Europe or North America to pursue higher degrees in public health or epidemiology. Until recently, there was only one school of public health in a country of a billion people. Thanks to a new public-private partnership, the Public Health Foundation of India, eight new schools of public health are being built around the country to teach the much-needed skills to students locally and to develop new research programmes. There is no doubt that this local injection of knowledge, skills and capability will lead to greater ability of Indian health professionals to use and produce evidence that is relevant to their health care system.
The poverty and premature death paradox
‘Poverty is as a strong a predictor of premature death today as it was a century ago’ reported a study on BMJ online this week. The study examined the geographical relationship between mortality and deprivation at the start of the 20th and 21st Century. Although there was a change in the number of deaths over this time, modern patterns of mortality and deprivation remain strongly linked to the patterns of a hundred years ago.
Their conclusion states ‘for all the medical and public health changes over this time, patterns of poverty and mortality and their relationship remain firmly entrenched.......... This relationship holds true for most major modern causes of death’.
If you bear with me for a few minutes I’ll explain why I think this occurs and the paradox that causes it.
Consider living in the most deprived areas of the country and survey one hundred 18 to 30 year-olds. Of these, 20 have long term health problems; for instance mental health problems. You decide over the next 10 years to invest considerably in health and for your investment you get a 20% reduction in chronic health problems, leaving you with 16 individuals still with chronic disease. However, 20 of the healthiest, educated and economically active individuals decide to become part of a common phenomenon: economic migration, whereby individuals emigrate from one area to another for the purposes of seeking employment or improved financial position. For the unhealthy this is normally not an option.
So what’s the paradox? Well when you resurvey you are left with 80 individuals of whom 16 have a chronic health problem. In effect 20% exactly the same figure we started with. Therefore, to me there seem only two solutions: one is to raise the average wealth of everyone, or second to take the economic activity to the areas which are the most deprived.
Is marketing the main problem with booze?
It’s been a bad week for booze lovers. An Oxford study estimated that in 2005, alcohol caused over 30 000 UK deaths, costing the NHS over £3 billion. 6% of deaths and 10% of all “ill-health” (as measured by "disability-adjusted life years”) are caused by alcohol. To put it in context, the same researchers showed last month that smoking caused 19% of all deaths and 12% of ill health, costing over the NHS £5 billion per year.
The President of the Royal College of Physicians, Dr Ian Gilmore, has made no secret of his desire to raise the profile of alcohol-related disease as a problem that can no longer be ignored. Writing in this week’s British Medical Journal, he speaks of “many factors that are deeply embedded in society and individual behaviours that influence how, why, and how much people drink. Previous public health campaigns, such as weekly alcohol limits, have been unsuccessful in reducing binge-drinking. On the other hand, the alcohol industry spends £800 million annually on marketing (about a quarter of what their product costs the NHS per year). A report commissioned by the British Medical Association shows that existing controls on alcohol advertising are inadequate, especially in young people, and as Gilmore says, “We should have learnt from tobacco that voluntary partnerships with the relevant industry do not work”. Calls are being made to curb merchandising, sponsorship of sporting events, competitions and loyalty schemes.
A systematic review of 13 studies of almost 40 000 young people found good evidence to support the impact of media exposure and alcohol advertising on subsequent alcohol use, including initiation of drinking and heavier drinking among existing drinkers. The UK is the only country in Europe with no restrictions on alcohol advertising and this method has been shown to work in other countries. Therefore, a Europe-wide ban on alcohol advertising has been recommended as a cost-effective health policy.
However, research and policy will have to be more innovative than simple bans if we are to change the current drinking behaviour of young people. For example, measures to change behaviours of college or university students were found to be more effective if they were web-based, compared with mail-based feedback.
Yet more evidence against aspirin in primary prevention
At the European Society for Cardiology Congress this week, we learned about more situations where aspirin is unhelpful. Professor Gerry Fowkes and colleagues from Edinburgh looked at nearly 30000 men and women aged 50 to 80 years who had never had any cardiovascular disease, but had a low ankle-brachial pressure index, a marker of peripheral vascular disease. The ankle brachial index (ABI) is the ratio of the blood pressure in the arm to the blood pressure at the ankle, and is an indicator of subclinical atherosclerosis. The ABI predicts risk of major vascular events in healthy populations, independently of established cardiovascular risk factors, such as diabetes, smoking and cholesterol. The Edinburgh team recruited over 3000 people with low ABI from their population and randomised them to 100mg aspirin or placebo, with 8 years of follow-up.
There was no difference between aspirin and placebo whether we look at cardiovascular events or all cause mortality, and there were more major bleeds in the aspirin arm of the trial. Same bottom line as before: do not give aspirin to people before they have a vascular event.