Finished the week in Istanbul. It’s a wonderful city – just a pity that I rarely manage to get time to see any of it! I was there for an investigators meeting on the Prospective Urban and Rural Epidemiology (PURE) Study. This is a really fascinating study and it is a great experience to be part of it. It has been put together by Salim Yusuf at McMaster University, in Canada, and involves many of the teams from his earlier INTERHEART study. The basic idea behind PURE builds on the results of INTERHEART. It showed that nine basic risk factors (smoking, hypertension, diabetes, abdominal obesity, psychosocial factors, abnormal lipids, fruit & vegetable consumption, alcohol consumption, and regular physical activity) explained a very substantial proportion of the variation in myocardial infarctions in populations from all regions of the world. It was a remarkable study, managing to gather data on 15,000 cases of myocardial infarction from 52 countries.
It is, however, clear that exposure to many of these risk factors is changing rapidly in many parts of the world, and often not for the better. In particular, in many developing and middle income countries life is changing rapidly for people in rural areas and in the per-urban sprawl around many large cities. PURE is recruiting subjects in urban and rural areas in about 20 countries so far, with the aim of following them up over the long term to see how their environments and their lifestyles change, and what impact this has on their health. So far, there is participation from every continent, but the largest numbers are from India and China. Remarkably, despite the enormous problems in the country, we even have participation from Zimbabwe, where there is a quite exceptional team.
The basic design is a cohort study, collecting data on people now and following them up into the future. However, where it differs is that it is looking at the environment within which people live. We know that many people want to make healthy choices, in relation to things such as smoking, diet, and physical activity. Yet too often their environment shapes the choices they can make. To take a few extreme examples, if you live in the mountains of Tibet you have very little choice but to walk if you want to get somewhere while if you are in Los Angeles you have very little choice to take a car. Similarly, in California it is actually quite difficult to smoke, or at least to find somewhere where you can light up, while in China it is difficult not to inhale smoke, even if it is someone else’s.
While it is easy to locate the extremes of these scales, such as the extent to which an environment discourages smoking or encourages exercise, it is far more difficult to place the communities we are studying in between these two poles. Smoking is perhaps the easiest. We can measure the density of tobacco sales outlets and advertising billboards and the extent of advertising in print media. Armed with handheld GPS devices and cameras, we can even map and photograph them. We can also see what proportion of bars actually ban smoking. However other areas are more difficult, when you are trying to work on a global scale. For example, it is fairly straightforward to measure the density of McDonalds, Kentucky Fried Chicken, and the like if you are doing a comparison across the USA. It is much more difficult to define calorie rich fast food in countries where these chains are still relatively uncommon and where people instead get their fat and salt from street vendors. Anyway, this is what a small group of us, from McMaster, Harvard, and LSHTM, are trying to do. Any ideas will be gratefully received!