JRSM >
Volume 96, Number 12 >
Pp. 613-614
London School of Hygiene and Tropical Medicine, London, UK
At a meeting in Bethesda in 1978, a group of investigators struggled to make sense of the observed decline in cardiovascular mortality in the USA and conceived a study that would go on to track cardiovascular risk factors and outcomes in 38 populations, in 21 countries, over 23 years. Now Hugh Tunstall-Pedoe has chronicled the history and achievements of this first global epidemiological study, the WHO MONICA Project, which has contributed so greatly to our understanding of the causes of cardiovascular disease and stroke. In particular, the findings have emphasized the importance of time lags between exposure and outcome, the imprecise association between traditional risk factors (such as blood pressure and cholesterol) and adverse cardiovascular outcomes, and the greater than expected evidence for the benefits of healthcare. As the project draws to a close (although the data collected will be subject to many further analyses in the years to come), this is a good time to take stock.
The book begins by tracing the development of the collaboration and proceeds to describe how the investigators sought to achieve standardized data collection. Then follow a description of each of the MONICA centres and abstracts of the most important papers arising from the project. The final section reviews the populations, their changing risk factors, and the main hypotheses tested, each illustrated by a set of high-quality graphics. The book comes with two CD-ROMs which contain a wealth of additional information, including the data collection manuals and 20% samples of data from each centre. It therefore provides not only an account of modern epidemiological history but also an important source of material for researchers in cardiovascular epidemiology.
In assembling this wealth of material, the editor has presented us with what is unashamedly, and quite justifiably, a celebration of this enormously complex project. Yet there are still large gaps in our knowledge and it is almost unimaginable that an enterprise on this scale will ever be conducted again. Before looking at the limitations of MONICA, one must pay tribute to the amazing feat of launching it at all. The long list of grants indicates just how much time the MONICA investigators must have spent raising funds. They were not always successful, as when they failed to secure European Union funding for what would have been a very important add-on study on nutrition. The MONICA Project succeeded only because of the dogged determination of a large number of people, from many countries, who were committed to a common vision and were able to follow it through.
It is easy to forget the challenges facing those involved in an international collaboration in the early 1980s. In a fascinating section on communications we are reminded that, although a few centres had telexes, fax machines were not yet available and international telephone calls were prohibitively expensive. Instead, communication took the form of a 'MONICA Memo', sent as an official communication by WHO and taking several weeks from initiation to reply (although JRSM readers facing demands for instant replies to several hundred e-mails each day may feel a wave of nostalgia). On the other hand, the MONICA workers may have found it easier to get ethical approval for their studies than today's investigators, who must surmount hurdles put in place by a bioethics industry that often seems to have lost sight of the goals of public health research. We should note that, despite working to guidance that some bioethicists would now consider obsolete, the investigators are able to report that there have been no breaches of confidentiality or ethical complaints.
But what might, in ideal circumstances, have been different? One issue is geographical coverage. Although the centres span four continents, they are concentrated overwhelmingly in Europe. There were no centres in South America and only one in Asia, Beijing. A centre in Japan participated initially but was unable to continue. Ironically, it is the evidence from the MONICA Project that has pointed out why a greater diversity would have been important, as it becomes increasingly clear that risk factor scoring systems developed in one setting have limited predictive power elsewhere (see for example Hense et al., Eur Heart J 2003; 24: 937–45).
A second is the changing understanding of the determinants of cardiovascular disease. Again largely as a consequence of the MONICA Project, we now know that the traditional risk factors, and in particular lipids, have only limited explanatory power in many populations. Instead, there is growing evidence of the importance of dietary components other than fat, in particular fruit and vegetables. There is also growing understanding of the complexity of the disease process, not least endothelial dysfunction, although a casual observer of the debate on the use of statins could be forgiven for thinking that this understanding has not yet spread very widely. We must now await the results of research such as that from the EPIC study (see Khaw et al., Lancet 2001; 357: 657–63), to shed light on these relationships. A third is the changing nature of cardiovascular disease, and the large increase in 'myocardial infarctions' that followed a redefinition of the disorder based mainly on troponin measurement. These observations, of course, are made with the benefit of hindsight. They do not detract from the great achievements of this project and those whose vision and commitment made it possible. This book is a fitting testament to their work.
Footnotes
Editor: H Tunstall-Pedoe, for the WHO MONICA Project
244 pp Price CHF
45 (US$40.50)—Special price in developing countries, CHF 30.50 ISBN
92-4-156223-4 (p/b)
Geneva: World Health Organization, 2003
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