Research links wealth to disease rates
U of C study breaks new medical
ground

David Heyman Calgary Herald Sunday, August 31, 2003

Encouraging people to eat well, exercise and stop smoking could have less
of an impact on cancer and heart disease than redistributing wealth more
evenly, according to a new study by a University of Calgary researcher.

James Dunn has spent years aiming to establish the premise that the main
causes of diseases that afflict western cultures have less to do with
lifestyle and genetics and more to do with much broader social
characteristics such as job status and income disparity.

His recent study shows that North American cities with drastic divisions
between rich and poor are unhealthier places to live than cities whose
income differences are less stark.

The results show the greater the income disparity, the more deaths from
various causes such as heart disease, cancer and homicide.

This phenomenon is true even between cities whose average income is the
same, but where one has a far more obvious income disparity, said Dunn, an
assistant professor in the U of C's department of community health
sciences.

In the United States, the difference is so profound that, hypothetically,
if the richer half of the population gave just one per cent of their
income to the poorer half, it would prevent 22 deaths a year per 100,000
population, the study found. That would be equal to all the deaths from a
major disease.

However, Canada's strong social safety net appears to have a strong
protective effect on such cities compared to similar ones in the U.S., he
said.

Dunn and Nancy Ross of McGill University in Montreal studied census data
from 302 metropolitan areas in North America with populations greater than
50,000 -- 53 in Canada and 249 in the United States.

They used an index of several criteria to measure the degree to which poor
areas are distinct and isolated from rich ones in cities, relying on
Canadian data from 1991 and U.S. data from 1990.

Dunn said a transfer of income from the richer half of the population to
the poorer half would make little difference in Canada.

"Canada is about as highly segregated as the U.S., but in the U.S. it
seems to have a more corrosive effect," he said.

This is because public services and goods are more often distributed
locally in this country.

While school and property taxes are generally shared broadly in Canada, in
the United States they more often stay in the communities in which they
were collected.

For example, in the U.S., the rich will more often pay property and school
taxes in the suburban communities where they live, but use services in
inner cities where they work, and which others have to maintain.

While that dynamic exists in Canada, too, our national safety net appears
to give lower-income people more buying power than they would have just
from their paycheques.

For example, Americans must pay for health-care insurance and other
services poor people in Canada get free of charge.

In addition to local distribution of goods and services, there are at
least two other possible reasons for this phenomenon, according to the
researchers:

- Obvious differences may promote jealousy among the poor, and stress
among the rich, exacerbating the negative psychological effects of
inequality and leading to physical health problems.

- The disparity creates corrosive social relationships within the
impoverished communities themselves, feeding jealousy, resentment and
depression, and causing more murders and suicides, for example.

These findings follow another study by Dunn, Ross and others published in
2000 that showed a strong association between income disparity and death
in the United States, but little connection in Canada.

Dunn's latest research on three other countries' income disparity shows
Australia and Sweden are more like Canada, while the United Kingdom is
more like the U.S.

These studies are in step with others completed on the topic by other
researchers around the world. All of them point to the possibility that,
when looking for causes of death, lifestyle differences within populations
are less significant than differences between populations.

A British scientific investigation, called the Whitehall study, tracked
17,000 civil servants in greater London between the 1970s and '80s.

It found those at the bottom of the rigid job hierarchy had a four times
greater risk of death from heart disease than those at the top.

Even after discounting the effect of factors such as smoking, cholesterol
level, blood pressure, glucose tolerance, body-mass index and so on,
people on the lowest rung of the organizational ladder were still 2.6
times more likely to die of heart disease.

The Whitehall study also argued that the known risk factors for coronary
heart disease explain just 35 per cent of the variation in deaths between
job classes.

It could then be argued, said Dunn, that the job hierarchy itself accounts
for the remaining 65 per cent, though the Whitehall authors say it remains
"unexplained."

Author Richard Wilkinson argues in his recent book Unhealthy Societies
that unequal societies such as the U.K. and the U.S. have much higher
proportional deaths from certain diseases and lower life expectancies than
nations where income is distributed more evenly.

It's no accident that Sweden and Japan both have long life expectancies
and narrow income differences, Wilkinson said in an interview last year
with the Edmonton Journal.

"There's a five to 15-year difference in life expectancy between those in
unskilled manual occupations and those in professional occupations," said
Wilkinson, a senior research fellow at the Trafford Centre for Medical
Research in Sussex, England.

Dunn's research has also shown that Canada appears to be becoming more
unequal.

The reason most studies don't include income disparity as a cause for
disease is that scientists actively try to eliminate its effect from their
research, said Dunn.

They do this in order to accurately measure the impact of the drug, herb
or chemical they are testing.

Dunn and other social scientists have long believed this practice ignores
the underlying causes of diseases.

"Every time you hear the results of a new clinical trial reported, or a
study claiming the health benefits or health hazards of a particular food
or substance, they have probably controlled for the effect of
socio-economic status," he said.

"They may well be controlling for things that have a far greater effect on
the health outcome than the variable they've isolated."

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