Politics as a determinant of health
http://www.100md.com
《英国医生杂志》
1 BMJ, London WC1H 9JR cmartyn@bmj.com
So, Franco et al found that people living in democracies enjoy better health than those who must endure repressive regimes.1 That's good to know—at least for those fortunate enough to live in freedom. But, in a perverse kind of way, I cannot help thinking that it would have been more interesting if things had been the other way around. Suppose it turned out that one had to pay a price, in terms of health, for the privilege of living in an electoral democracy. It would certainly have given us cause to reflect on the value we place on our rights and institutions.
As a thought experiment, imagine that you are a participant in one of those time trade-off investigations that health economists use to determine the utility of different states of health. Ask yourself how many years of life you would be prepared to sacrifice to gain a vote? Or how high a level of infant mortality you would tolerate in exchange for freedom of association and the right to say what you liked without fear that the secret police would come knocking?
Strength of evidence
Actually, I doubt that anyone would have believed it had the finding been the other way around. No matter how hard you try to guard against it, there is always a tendency to require a higher standard for evidence that challenges your prejudices than for evidence that supports them. If health had been positively associated with political repression, would the paper have survived peer review and the rigours of the selection process of the BMJ?
This sort of ecological survey is notoriously vulnerable to confounding. The investigators tried to take account of wealth, inequality, and the size of the public sector in their analysis, but surely peer reviewers would have queried whether the link between democracy and health was weaker in the multiple regression model by the inclusion of education, birth rate, the age structure of the population, and civil war? Provision of education seems especially likely to be a confounding variable since it is well established that women's education in particular has strong negative effects on both fertility and infant mortality,2 and that democracies spend more on education.3
I also suspect that reviewers and editors would have demanded a finer grained analysis if the results had been different. The investigators do not explain why they used the three categories of free, partially free, and not free to characterise the extent of democracy when Freedom House rates each country on a 7 point scale both for political rights and for civil liberties and makes these data available on its website.4 The quality of the data was also problematic. Although the information on life expectancy and maternal and infant mortality from the Human Development Report is no doubt the best available, the report acknowledges its many gaps and discrepancies.5
Implications
Let us put methodological issues aside and take the findings at face value. What can we usefully make of this cross sectional association between political freedom and health? After all, it is obvious that the way people live (and therefore how healthy they are) is shaped by political, social, demographic, economic, and cultural forces. Choices made by individuals about what they eat, where they work, what they do in their leisure time, the age at which they start their families, and how they look after their children are inevitably and heavily influenced by the society in which they live.
Our current preoccupation with risk factor epidemiology tends to obscure the fact that many of the forces that affect health and disease operate not at an individual level but on groups. The biological mechanisms by which these group level forces act are often obscure, but one example to the contrary is herd immunity. Although herd immunity is a powerful determinant of a person's risk of infectious disease, it is not a property that can be adequately captured by making measurements on individuals. The effects on health of large scale forces such as urbanisation, industrialisation, population growth, changes in the age structure of the population, racial discrimination, poverty, and inequality are likely to be profound. Franco et al would like us to add democratisation to this list and argue that there's a need for political epidemiology. If they mean that we should think about and investigate how the way a society organises and conducts itself affects the health of its members, who could disagree?
Competing interests: None declared.
References
Franco A, Alvarez-Dardet, Ruiz MT. Effect of democracy on health: ecological study. BMJ 2004;329: 1421-3.
Brown DS. Democracy and gender inequality in education: a cross national examination. Br J Polit Sci 2004;34: 137-92.
Brown DS, Hunter W. Democracy and human capital formation—education spending in Latin America, 1980 to 1997. Comp Polit Stud 2004;37: 842-64.
Freedom House. www.freedomhouse.org/reseach/freeworld/2003/metholodogy.htm
Human Development Report. Note on statistics. hdr.undp.org/statistics/about/note_on_stats.cfm (accessed 10 Dec 2004)(Christopher Martyn, assis)
So, Franco et al found that people living in democracies enjoy better health than those who must endure repressive regimes.1 That's good to know—at least for those fortunate enough to live in freedom. But, in a perverse kind of way, I cannot help thinking that it would have been more interesting if things had been the other way around. Suppose it turned out that one had to pay a price, in terms of health, for the privilege of living in an electoral democracy. It would certainly have given us cause to reflect on the value we place on our rights and institutions.
As a thought experiment, imagine that you are a participant in one of those time trade-off investigations that health economists use to determine the utility of different states of health. Ask yourself how many years of life you would be prepared to sacrifice to gain a vote? Or how high a level of infant mortality you would tolerate in exchange for freedom of association and the right to say what you liked without fear that the secret police would come knocking?
Strength of evidence
Actually, I doubt that anyone would have believed it had the finding been the other way around. No matter how hard you try to guard against it, there is always a tendency to require a higher standard for evidence that challenges your prejudices than for evidence that supports them. If health had been positively associated with political repression, would the paper have survived peer review and the rigours of the selection process of the BMJ?
This sort of ecological survey is notoriously vulnerable to confounding. The investigators tried to take account of wealth, inequality, and the size of the public sector in their analysis, but surely peer reviewers would have queried whether the link between democracy and health was weaker in the multiple regression model by the inclusion of education, birth rate, the age structure of the population, and civil war? Provision of education seems especially likely to be a confounding variable since it is well established that women's education in particular has strong negative effects on both fertility and infant mortality,2 and that democracies spend more on education.3
I also suspect that reviewers and editors would have demanded a finer grained analysis if the results had been different. The investigators do not explain why they used the three categories of free, partially free, and not free to characterise the extent of democracy when Freedom House rates each country on a 7 point scale both for political rights and for civil liberties and makes these data available on its website.4 The quality of the data was also problematic. Although the information on life expectancy and maternal and infant mortality from the Human Development Report is no doubt the best available, the report acknowledges its many gaps and discrepancies.5
Implications
Let us put methodological issues aside and take the findings at face value. What can we usefully make of this cross sectional association between political freedom and health? After all, it is obvious that the way people live (and therefore how healthy they are) is shaped by political, social, demographic, economic, and cultural forces. Choices made by individuals about what they eat, where they work, what they do in their leisure time, the age at which they start their families, and how they look after their children are inevitably and heavily influenced by the society in which they live.
Our current preoccupation with risk factor epidemiology tends to obscure the fact that many of the forces that affect health and disease operate not at an individual level but on groups. The biological mechanisms by which these group level forces act are often obscure, but one example to the contrary is herd immunity. Although herd immunity is a powerful determinant of a person's risk of infectious disease, it is not a property that can be adequately captured by making measurements on individuals. The effects on health of large scale forces such as urbanisation, industrialisation, population growth, changes in the age structure of the population, racial discrimination, poverty, and inequality are likely to be profound. Franco et al would like us to add democratisation to this list and argue that there's a need for political epidemiology. If they mean that we should think about and investigate how the way a society organises and conducts itself affects the health of its members, who could disagree?
Competing interests: None declared.
References
Franco A, Alvarez-Dardet, Ruiz MT. Effect of democracy on health: ecological study. BMJ 2004;329: 1421-3.
Brown DS. Democracy and gender inequality in education: a cross national examination. Br J Polit Sci 2004;34: 137-92.
Brown DS, Hunter W. Democracy and human capital formation—education spending in Latin America, 1980 to 1997. Comp Polit Stud 2004;37: 842-64.
Freedom House. www.freedomhouse.org/reseach/freeworld/2003/metholodogy.htm
Human Development Report. Note on statistics. hdr.undp.org/statistics/about/note_on_stats.cfm (accessed 10 Dec 2004)(Christopher Martyn, assis)