a Department of Social Medicine, University of Bristol, Canynge Hall, Whiteladies Road, Bristol BS8 2PR, UK. E-mail: shah.ebrahim{at}bristol.ac.uk
b Department of Community and Family Medicine, The Chinese University of Hong Kong, Hong Kong.
The emerging burdens of chronic non-communicable disease in the developing world are stubbornly resistant to prevention given the limited infrastructure, the competing priorities of communicable diseases and trauma and limited resources. Worldwide, there are approximately 55 million deaths each year, over half of which occur in people less than 60 years of age. Communicable diseases account for 31%, non-communicable diseases for 60% and injuries for 9%.1 However, this mortality picture does not give a good indication of just how sick the population is. Disability-adjusted years provide a different lens through which to examine burdens of disease and produce rather different rank ordering of priority health problems, in particular highlighting the importance of injuries.2
Geoffrey Rose's paper3 deals with three major issues that are of continued relevance to developing countries. First, the causes of incidence are not necessarily the same as the causes of individual susceptibility. In the developing world, poverty is the most obvious cause of the incidence of infant mortality, and morbidity associated with malnutrition and infections. In aetiological studies, xerophthalmia is associated with failure to eat vitamin A containing foods.4 This results in a magic bullet solutionoral vitamin A supplements.5 However, it is apparent that the wider determinants of this problem are socialpoverty and maternal education being of primary importance, which in turn are dictated by cultural values in many countries.6 Tackling the social inequalities within and between populations is not on any international or bilateral aid donor agenda. Rather, special programmes with short-term, explicit and measurable objectives have been established with a magic bullet or eradication model in mind. Examples include the distribution of vitamin A capsules in an attempt to deal with xerophthalmia,6 polio and malaria eradication programmes given new life by the Bill Gates Foundation, and the safe motherhood programme.7 Furthermore, the adverse effects of restrictions imposed by donor agencies may result in distortion of health priorities, leading to health policy being determined by ministers of finance.8 More flexible and innovative non-governmental organizations have attempted to tackle poverty through income generation schemes but these, by their nature, lack the ability to provide long-term influence.
The second issue is the need to consider both high risk and population strategies in prevention. The population approach has the wonderful attraction of achieving a lot at low costshifting the population distribution downwardsbut the social and economic pressures we are under are pushing the population distribution of many risk factorstotal cholesterol, blood pressureupwards. Even more insidious is the marketing of cigarettes to people in the south and south east Asian regions. The numbers of potential smokers will more than make up for the loss of smokers in the west. These trends are likely to ensure that global inequalities of health are magnified. High-risk prevention strategies appeal to doctors, who tend to be major power brokers in poorer countries. Consequently, diversion of resources from primordial prevention to the identification and treatment of cardiovascular risk factors and coronary heart disease and diabetes among the emerging, relatively wealthy, urban populations of poorer countries is now evident. In poorer countries, the dominance of high-risk strategies undermines much that might be achieved through preventive efforts, and consumes resources that should be used in existing maternal and child health programmes.
Rose's third theme was the prevention paradox. Few will benefit but all have to take part. In Chinese communities, most children are taught a Confucian truth at an early age: a single chopstick can be broken easily with little force, a bundle of chopsticks are virtually impossible to break. Solidarity among people is a powerful weapon (and also, in the case of adverse health behaviours, a major barrier) in the public health medicine arsenal. The International Epidemiological Association has a role to play in creating and sustaining a united front among epidemiologists and the wider public health community in their efforts to promote public health. Such work requires real determination and will to stand up to powerful vested interests.
Unfortunately, for many epidemiologists, a fixation with case-control methodology and the production of ever more carefully adjusted odds ratios, getting closer to unity (but still statistically significant) does little to help practical public health. Studies that generate attributable measures of benefit or harm, such as numbers needed to screen or number needed to prevent would provide more meaningful estimates of the public health workload and tangible estimates of just how small (or large) the benefit will be for individuals.
So what do we do? Very little research has been focused on the determinants of variation in disability adjusted life years (DALY) between and within populations. It is likely that Rose's concerns about the causes of incidence and susceptibility will be even more pronounced when the additional component of disability is taken into account. Since so much disability is socially determined, it is very likely that variation in DALY will be very sensitive to socioeconomic factors. In seeking to reduce DALY, public health will be forced to confront the primordial forces that cause disease and disability in more direct ways, involving potentially more productive alliances and strategies with social development, education and employment agencies. It is time to invoke the mantra of an earlier hero of public health (and politics)Rudolf Virchowwho realised that mass diseases require mass solutions.9 A global solidarity between public health scientists and practitioners would help us all to remain focused on the main questionwhat must we do to improve the population's health?
References
1 World Health Organization. The World Health Report 2000. Health Systems: Improving Performance. Geneva: WHO, 2000.
2 Murray CJ, Lopez AD. Regional patterns of disability-free life expectancy and disability-adjusted life expectancy: global burden of disease. Lancet 1997;349:134752.[ISI][Medline]
3 Rose G. Sick individuals and sick populations. Int J Epidemiol 1985; 14:3238.[Abstract]
4 Mele L, West KP Jr, Kusdiono PA et al. Nutritional and household risk factors for xerophthalmia in Aceh, Indonesia: a case-control study. The Aceh Study Group. Am J Clin Nutr 1991;53:146065.[Abstract]
5 Sommer A, Tarwotjo I, Djunaedi E et al. Impact of vitamin A supplementation on childhood mortality. A randomised controlled community trial. Lancet 1986;i:116973.
6 Cohen N, Rahman H, Mitra M et al. Impact of massive doses of vitamin A on nutritional blindness in Bangladesh. Am J Clin Nutr 1987;45:97076.[Abstract]
7 Maine D, Rosenfield A. The safe motherhood initiative: why has it stalled? Am J Public Health 1999;89:48082.[Abstract]
8
Bhutta ZA. Why has so little changed in maternal and child health in south Asia? BMJ 2000;321:80912.
9 Eisenberg L. Rudolf Ludwig Karl Virchow, where are you now that we need you? Am J Med 1984;77:52432.[ISI][Medline]