Abstract
About
40 years ago, Thomas McKeown demonstrated that the historic decline in
the great killer diseases owed little or nothing to progress in
medicine. A generation of research on population health followed,
highlighting the large social gradients in health within populations.
These vary greatly across societies, but appear largely unrelated to
medical care. Medicine was acknowledged as “powerful, but within
limits”; the major determinants of health lie elsewhere.
We
may have missed something. Cuba has achieved “first world” population
health status despite a minimal economic base. Far from marginalizing
medicine, Cuba has by far the world's largest physician workforce. But
doctors' roles are significantly expanded. The system seems to work.
About
40 years ago, Thomas McKeown fired a shot across the bow of medicine
whose echoes still reverberate faintly. Studying mortality records for
England that go back to the first half of the 19th century, he
demonstrated that the very large declines in mortality from a number of
major infectious diseases pre-dated not only the development of
effective medical therapies but also scientific understanding of the
disease processes themselves (McKeown 1979).
The major killers of the 19th century are still around, but their
impact on the health of the English population, or any other high-income
population, has almost disappeared – for reasons quite independent of
medical progress. As a “diagnosis of exclusion,” McKeown “emphasized
instead the importance of economic growth, rising living standards, and
improved nutrition as the primary sources of most historical
improvements in the health of nations” (Szreter 2002).
Human
society has been transformed over the last century and a half by the
decline in mortality at all ages and the increase in life expectancies.
Over the same period there have been enormous advances in biomedical
science, and in the last half century these have translated into huge
increases in the resources devoted to the provision of medical care.
(Between 1960 and 2005, the share of greatly increased national incomes
spent on healthcare in OECD countries more than doubled; in the United
States it tripled.) It is intuitively plausible to assume that these
trends are causally linked – post hoc ergo propter hoc.
The
general public are happy to give modern medical care credit for these
great benefits, and the providers of care have been willing to accept.
McKeown's demonstration that correlation is not the same as causation,
at least with respect to infectious disease, was understandably
unpopular and controversial. He could not be directly refuted – the data
and the timing were what they were – but clinicians largely ignored his
observations. Anyway, that was then; this is now.
Furthermore,
McKeown somewhat overplayed his hand. His leading example,
tuberculosis, does in fact show a marked downturn in mortality rates in
the late 1940s, when effective medical therapy was developed. In the
long historical sweep, the overall decline is so large that it is easy
to miss this kink, but in relative terms – and to the patients and
doctors of the late 1940s – the effect was very significant. They might
understandably reject the claim that “medicine doesn't matter” while
missing the crucial point that on the larger historical scale, other and
more powerful factors had been at work.
But Public Health Matters -- or Did?
Perhaps
more seriously, McKeown took too restrictive a view of those other
factors. Because TB is not a water-borne bacillus, he argued that the
decline in TB mortality could not be a result of cleaner water and
better sewage disposal. Public health measures deserved no more credit
than medicine. This interpretation was effectively challenged by Szreter (1988), who noted that TB was an “opportunistic” infection, taking advantage of the presence of other infections that were
water-borne. Gastro-intestinal diseases, in particular, tend to reduce
the nutritional uptake from food consumption. But sanitary measures
reducing the prevalence of gastro-intestinal disease could then increase
the nutritional value of diets, and more generally improve “host
resistance.” No matter how wealthy you are, drinking sewage is a
seriously bad idea.
McKeown's medical scepticism
continues to find support, however, in aggregate data on population
health. When compared across high-income countries, measures such as
life expectancy, age-adjusted mortality or potential years of life lost
do not show a correlation with expenditures on healthcare or the
available supply of doctors or other personnel, or hospital capacity.
Nor, however, do they show any correlation with average per capita
income levels. In low- and middle-income countries there is quite a
strong correlation with both income and health spending, making it
impossible to infer anything about which, if either, is the more
important factor.
Yet there is within
high-income countries a more or less pronounced gradient in health that
is closely correlated with income, education and other measures of
social status. There is thus a paradox: within countries, income is correlated with health, but among
(high-income) countries, it is not. This observation underlies a
generation of research on the social determinants of health, with
particular interest in how social position influences health status, and
thus in the relative equality or inequality of social positions in
different societies.
Population Health and Medicine: Two Solitudes?
Medicine
is not among the potential explanations. Virtually all high-income
countries have more or less universal access to modern healthcare
systems, leading researchers to discount the significance of medical
care as an explanation of the social gradient. Where there are
identifiable populations with significantly restricted access to
healthcare, one can in fact observe corresponding health consequences –
as among the uninsured population in the United States. Medicine does
matter. But the more intellectually challenging question has been the
sources of the social gradient in the general populations of high-income
countries.
The marginalization of the medical
profession that was explicit in McKeown's findings has thus continued
through the subsequent generation of research on the determinants of
population health. No one would now deny the powerful contribution of
modern medicine to improvements in longevity, function and quality of
life of individuals. But it is, I think, fair to say that the general
attitude of students of population health is that medical care is
“powerful within limits” and cannot explain the major gradients in
health within populations any more than it can explain the historical
changes studied by McKeown.
This view has only been
strengthened by a generation of research on variations in patterns of
clinical care. The most intensive investigations, in the United States,
find that regions with greater volumes and higher costs of care actually
have no greater patient satisfaction, slightly worse mortality outcomes
and lower quality of care (see Evans 2007
for references). Where there are more doctors, and greater hospital or
equivalent capacity, costs are much higher but outcomes are worse, not
better.
It is therefore not surprising that study of
the social determinants of health has been viewed by most physicians
with at best, indifference and at worst, outright hostility. It is seen
as a potential threat to their status – and their incomes. (Ironically,
most of the leading students of the social determinants of health, from
Rudolf Virchow to Sir Michael Marmot and Fraser Mustard – and including
that medical iconoclast, Thomas McKeown – have been physicians.)
But students of population health (present company included) may have missed something.
The Black Swan
The
exception, it is often said, proves the rule. (“Proves” here has its
original meaning of testing, not confirming.) One black swan suffices
(subject to a bit of scrubbing) conclusively to refute the proposition
“All swans are white.” The Cuban experience, over the last 50 years, may
be just such a black swan. Spiegel and Yassi (2004: 204) refer to it as “the Cuban health paradox”:
It is widely recognized that Cuba, despite poor economic performance, has achieved and sustained health indices comparable to those in developed countries … .
The remarkable Cuban achievement with respect to population health emerges clearly from the World Health Report (WHR) (WHO 2006). Figures Figures1a1a and and1b1b
combine data from the Statistical Annex to show the relationship
between per capita GDP and two different measures of population health –
life expectancy at birth and expected mortality per thousand population
under five years of age.1
Both figures show a similar pattern, with a strong overall relation
between income levels and health status but with very important
qualifications.2
Life expectancy at birth plotted against GDP per capita, 139 countries
Mortality before age 5 plotted against GDP per capita, 139 countries
In
high-income countries there is no relationship between per capita GDP
and either of these measures of health status. For mortality under five
years of age, the relationship disappears above a per capita GDP of
$15,000; for life expectancy, there is some suggestion of a relationship
up to $20,000 per capita. But the relationship is unclear among
countries at the very lowest incomes. A fitted trend line would indicate
a very powerful relationship, but comparison of individual country
observations shows very large differences in health measures for
countries with the same reported levels of income. Inter-country
differences in factors other than income are obviously exerting a very
powerful effect on health – which is not the case for higher-income
countries.
And then there is Cuba.
High
up on the far left for life expectancy, and low down on the left for
under-five mortality (expanded circles), Cuba's health measures are
comfortably within the band of the highest-income countries while its
per capita income, at $3,438, places it 86th among the 139 countries
plotted – roughly in the middle of the third quartile. The health of
Cuba's population matches or exceeds, on average, that of the United
States. Among countries with similar income levels, the best achieve
under-five mortality rates twice that of Cuba, and the rest are three,
four or five times as high. The best life expectancies are five years
shorter; others are 10 or more years shorter. The differences are
extraordinary.
The world data span the full range of cultures and environments. Figures Figures2a2a and and2b2b
restrict attention only to the Americas. But they tell the same story,
permitting the graph to be spread out more widely. The wealth and good
health of Canada and the United States stand out on one side of the
figure; the poverty and ill health of Haiti on the other. But in number
two position on life expectancy, behind Canada and in a tie with the
United States, is Cuba. Chile and Costa Rica are right behind, but with
much higher income levels than Cuba. And on child mortality, Cuba edges
out the United States and Chile to lie right behind Canada. The margin
over other countries runs from large to very large.
Life expectancy at birth plotted against GDP per capita, the Americas
Mortality before age 5 plotted against GDP per capita, the Americas
So what is happening in Cuba? “There has been remarkably little scholarship evaluating how this has been accomplished …” (Spiegel and Yassi 2004).
This column will not fill that gap. But there is one other remarkable
feature of Cuban healthcare that does jump out of the WHR data.
Doctors and Good Health; No Clear Relationship, But …
Cuba's doctor-to-population ratio – 5.91 per thousand – is by a substantial margin the highest in the world.3 Figures Figures3a3a and and3b3b
show the reported physician-to-population ratios, for all countries and
for those only of the Western hemisphere, plotted against per capita
GDP. For countries with incomes under about $10,000 there appears (in
Figure Figure3a)3a)
to be a relationship between income levels and physician availability,
branching out from a large concentration of countries that have neither
money nor doctors. Above $10,000, however, there is no clear
relationship – the observations simply spray across the page.
Physicians per 1,000 population plotted against GDP per capita, 139 countries
Physicians per 1,000 population plotted against GDP per capita, the Americas
There
are many countries with a much greater physician supply than the United
States or Canada, even with incomes well below $10,000. But Cuba stands
out at the upper left, far above the next highest, Belarus at 4.55,
Belgium at 4.49 and Estonia at 4.48. There are a lot of doctors in Cuba.
Belgium
and Belarus, however, make a convenient comparison, underlining the
significance for health of the broader social context. Belgium's life
expectancy, at 78, matches that of Cuba or the United States, and the
under-five mortality of 5 is better than either Cuba (7) or the United
States (8). Life expectancy in Belarus is a full 10 years shorter, and
child mortality is exactly double that of Belgium. Estonia is between
the two, at 72 and 8.
Canada, on the other hand,
matches or exceeds the health outcomes of the most heavily doctored
European countries – Italy and Greece, as well as Belgium – with half as
many physicians. And Japan has fewer still (1.98 per thousand) and the
best outcomes in the WHR.
A focus on the Americas alone, as in Figure Figure3b,3b,
may avoid some of the more extreme variations in culture and geography.
But the tight clustering of American countries results from the
presence of extreme outliers with respect to income (Canada and the
United States) and physician supply (Cuba). There appears to be a slight
positive relationship within the main cluster, but any statistical fit
would be extremely sensitive to the inclusion or exclusion of outliers.
There are, however, a handful of other countries besides Cuba that have
relatively high physician-to-population ratios, without achieving
comparable health outcomes (Table (Table11).
Physician supply, life expectancy, mortality under age five and GDP per capita, the Americas
The
other American states with particularly high physician availability
show health outcomes markedly inferior to those in Cuba. The wealthy
North American pair achieves results comparable to Cuba with many fewer
physicians, but Mexico, with a physician supply not far below that in
Canada, has significantly poorer outcomes. On the other hand, Chile,
with about half as many physicians as Mexico or Canada, has health
outcome measures comparable to the United States – and less than
one-third the per capita income. That still amounts, however, to over
three times the per capita income of Cuba.
Wealth and Health: Neither Necessary Nor Sufficient?
I
promised above not to offer an explanation for the “Cuban Paradox,” but
the combination of “first world” health statistics from a “third world”
economic base, like the black swan, refutes “the conventional
assumption that generating wealth is a fundamental precondition for
improving health” (Spiegel and Yassi 2004).
There is certainly a strong cross-national association between health
and wealth over part of the income range, although the association
disappears above relatively modest levels of average income. But there
are alternatives; increased wealth is not a necessary condition for
improved health, even among middle- and low middle–income countries.
Nor is it a sufficient condition. The strong relationship shown in Figures Figures1a1a and and1b1b
covers a considerable degree of diversity in the middle-income ranges.
Costa Rica, with a per capita GDP of $8,438, has an average life
expectancy of 77 years – just below the United States and Cuba. South
Africa, with an income of $7,964, has a life expectancy of 48 years.
Kazakhstan ($9,000) has a life expectancy of 61, while Thailand ($7,879)
and Brazil ($7,855) have life expectancies of 70.
If
McKeown was right – that increasing wealth is the highway to better
health – a number of countries seem to have misplaced the map.
Conscious Political Will – and People Trained to Carry It Out
Szreter's
response to McKeown goes well beyond the epidemiology of tuberculosis.
The much broader issue is the role of explicitly targeted social policy,
of “an accompanying redistributive social philosophy and practical
politics” (Szreter 2002)
in the 19th century public health movement, simultaneously with the
trends observed by McKeown. The revolution in population health over the
last two centuries was not simply a side effect of a rising GDP, it was
achieved through the deliberate intentions and actions of people with a
social agenda. Any idea that “go for growth, and all else will be added
unto you” would be a dangerous distortion of the historical reality.
The
Cuban experience strongly supports the importance for population health
of deliberate social action, of a very explicit focus not only on
medical care but on the non-medical determinants of health: education,
nutrition, housing, employment and social cohesion. Pursuit of such
policies ultimately requires political determination, although in
countries with other political regimes, increasing wealth may have been
part of the process of mobilizing support.
But what about all those Cuban doctors?
Szreter
appears to take a relatively benign view of McKeown's “rhetorically
powerful criti[que], from the inside, of the medical profession's
mid–20th-century love affair with curative and scientific medicine” (Szreter 2002).
It is the dismissal of public health, broadly or narrowly interpreted,
that he challenges, not the medical scepticism. But there is no medical
scepticism in Cuba. Along with efforts to address a broad range of
non-medical determinants of health, Cuba has trained by far the world's
largest supply of physicians per capita. Rather than seeing medical and
non-medical determinants as competitive, Cuba has chosen, despite very
limited resources, to go for both.
The difference
appears to be that in Cuba, primary care physician (and nurse) teams
have responsibility for the health of geographically defined
populations, not merely of those patients who come in the door. These
teams are then linked to community- and higher-level political
organizations that both hold them accountable for the health of their
populations and provide them with channels through which to influence
the relevant non-medical determinants. To take on these roles, the medico familiar integrale (MFI) is trained in both the medical and the non-medical aspects of health.
Cuba has made operational the ideas sometimes described as “Community-Oriented Primary Care” (COPC) (Nutting 1984).
The medical care system, rather than working in isolation from the
non-medical determinants of health, becomes a key part of the process,
the mechanisms of social intervention, through which those non-medical
determinants are addressed. And the success or otherwise of those
interventions is then reflected in the epidemiological data collected as
part of the regular functioning of the medical care system. More
doctors, but with broader training and scope, more responsibility and
institutionalized access to political authority.
Research
on population health has made great progress in elucidating the
determinants of population health, but has been much less successful in
identifying the levers for translating this understanding into specific
policies. The Cubans appear to have re-focused and heavily resourced
medicine to address the non-medical determinants as well. The split
between population health and clinical medicine that traces back to
McKeown may have deprived population health of one of the most powerful
mechanisms for translating understanding into practice.
On
the other hand, it is highly unlikely that the ideological framework of
clinical medicine in high-income societies could ever have permitted
such a relationship, nor that the broader political context could
sustain it. Has anyone heard of COPC lately? Anyway, our societies are
achieving average levels of population health that match or exceed
Cuba's, albeit at more than 10 times the cost for healthcare. And if we
preserve a pronounced social gradient in health, well, it could be
worse. I'm all right, Jack.
Notes
1.The
WHR tables include 192 countries, but I have excluded several for which
the WHR advises “caution” in the use of the data. I have also
arbitrarily excluded “micro-states” with populations less than one
million from the world figures but not from the Americas, leaving 139
and 35 data points, respectively.
2.A version of Figure Figure1b,1b,
fitted in double logs with country points scaled to relative
populations and colour-coded by continent, has been prepared by Hans
Rosling of the Karolinska Institute. It shows the outlier status of Cuba
even more dramatically, but was beyond our technical competence to
reproduce. Available on request.
3.Actually,
the highest ratio, 47.51, is in the Republic of San Marino – population
29,600 – but one has to suspect a tax haven. Coincidentally, according
to the WHR, Canada and Cuba have virtually identical numbers of
physicians (66,583 and 66,567), but Canada has only 2.14 physicians per
capita.
References
- Evans R.G. Extravagant Americans, Healthier Canadians: The Bottom Line in North American Health Care. In: Thomas D.M., Torrey B.B., editors. Canada and the United States: Differences That Count. Peterborough, ON: Broadview Press; 2007. pp. 135–64.
- McKeown T. The Role of Medicine: Dream, Mirage or Nemesis? 2nd ed. Oxford: Basil Blackwell; 1979.
- Nutting P.A., editor. Community Oriented Primary Care: A Practical Assessment. Volumes 1–2. Washington, DC: Institute of Medicine; 1984.
- Spiegel J.M., Yassi A. Lessons from the Margins of Globalization: Appreciating the Cuba Health Paradox. Journal of Public Health Policy. 2004;25(1):96–121. [PubMed]
- Szreter S. The Importance of Social Intervention in Britain's Mortality Decline c. 1850–1914: A Re-interpretation of the Role of Public Health. Society for the Social History of Medicine. 1988;1(1):1–37.
- Szreter S. Rethinking McKeown: The Relationship between Public Health and Social Change. American Journal of Public Health. 2002;92(5):722–25. [PMC free article] [PubMed]
- World Health Organization. World Health Report 2006 – Working Together for Health. Geneva: Author; 2006. [PubMed]
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