Income inequality, individual income, and mortality in Danish adults: analysis of pooled data from two cohort studies
BMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7328.13 (Published 05 January 2002) Cite this as: BMJ 2002;324:13All rapid responses
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Several papers in this week’s BMJ have demonstrated the importance of
factors other than population income in explaining mortality differences.
In Denmark, adjustment for individual risk factors made an apparent effect
on area income inequality on all cause mortality disappear,1 while in
Japan, individual income has a stronger association with self-rated health
than income inequality at a community level,2 and in the USA lack of high
school education accounted for a significant proportion of the income
inequality effect.3
Data from rural and remote Australia also support this finding. In
particular, racial differences play an important part in explaining
differences in mortality rates. Although Aboriginal and Torres Strait
Islander death rates are declining, they have failed to keep pace with
declines in the Australian population as a whole.4 Based on 1992-94
mortality data, life expectancy for Indigenous peoples is still much less
than for their non-Indigenous counterparts, with a difference in life
expectancy at birth of 14-18 years between Indigenous and non-Indigenous
males. The leading cause of death for Indigenous peoples continues to be
cardiovascular disease, with death rates at more than three times those
obtained in the non-Indigenous population.4,5
Diabetes-related mortality is higher in remote areas of Australia than in
urban and rural areas, which is explained by the fact that Indigenous
Australians account for two-thirds of diabetes-related deaths in remote
areas. Indigenous Australians are twice as likely to die from diabetes-
related deaths as non-Indigenous Australians.6 This difference is
substantially higher among the 35-44 age group, where the proportion of
deaths among Indigenous Australians is six times that of non-Indigenous
Australians.
Similarly, deaths from respiratory diseases were seven times more common
than for the non-Indigenous population in 1992-1994, and did not reduce
significantly from 1985 to 1994, and deaths from diabetes rose
significantly during the 1985-94 period, with increases of 10% per year in
males and 5% per year in females. Indigenous men were 12 times more likely
to die from diabetes than non-Indigenous men, and Indigenous females were
17 times more likely to die of the disease.
By concentrating on income, the risk is that more important differences
between communities will be missed. If we are to improve the health status
of our most disadvantaged groups then we must address their needs and take
care not to use preconceived notions of disease causation.
1 Osler, M., Prescott, E., Gronbaek, M., Christensen, U., Due, P.,
Engholm, G. Income inequality, individual income, and mortality in Danish
adults: analysis of pooled data from two cohort studies. BMJ 2002, 324, 1-
4.
2 Shibuya, K., Hashimoto, H., Yano, E. Individual income, income
distribution, and self-rated health in Japan: cross sectional analysis of
nationally representative sample. BMJ 2002, 324, 1-5.
3 Muller, A. Education, income inequality, and mortality: a multiple
regression analysis. BMJ 2002, 324, 1-4.
4 Anderson, P., Bhatia, K., 1996. Cunningham, J. Mortality of Indigenous
Australians. Australian Bureau of Statistics.
5 Mathur, S., Gajanayake, I., 1998. Surveillance of cardiovascular
mortality in Australia 1985 – 1996. AIHW cat. No. CVD 3. Canberra:
Australian Institute of Health and Welfare (Cardiovascular disease series
no. 6).
6 Mathur S, Gajanayake I & Hodgson G 2000. Diabetes as a cause of
death, Australia, 1997 and 1998. AIHW Cat. No. CVD 12. Canberra: AIHW
(Diabetes Series no. 1).
Competing interests: No competing interests
Income inequality and primary care
To Editor:
None of the four research reports on income inequalitiy1-4 or the
commentary5 mentioned some important research findings regarding the
relationship between income inequality, primary care, and various measures
of health, even though existing studies6-9 were carried out on various
levels of aggregation (states, metropolitan areas, communities) with a
variety of variables, both individual and ecological. Our studies have
consistently found a modest relationship of income inequality and health,
but a much greater relationship of primary care physicians to population
ratios. Thus, a measure that reflects a specific health policy component
and a material explanation for health effects is strongly suggested. We
also found a larger effect of primary care in areas where income
inequality is greatest.
In concert with the recommendations of several authors, we encourage
the consideration of alternative conceptual frameworks for path effects,
and inclusion of a broader range of specific characteristics suggested by
them as likely to have an impact on health, including, but not necessarily
limited to, primary care resources, access, and use.
Sincerely,
Barbara Starfield, MD, MPH, FRCGP
Johns Hopkins University School of Public Health,
624 North Broadway, Room 452,
Baltimore, MD 21205,
USA
e-mail address: bstarfie@jhsph.edu
1. Osler MO, et al. Income inequality, individual income, and
mortality in Danish adults: analysis of pooled data from two cohort
studies. BMJ 2002: 324: 13.
2. Shibuya K, et al. Individual income, income distribution, and self
rated health in Japan: cross sectional analysis of nationally
representative sample. BMJ 324: 16.
3. Sturm R, Gresenz CR. Relations of income inequality and family income
to chronic medical conditions and mental health disorders: national
survey. BMJ 2002; 324: 20.
4. Muller A. Education, income inequality, and mortality: a multiple
regression analysis. BMJ 2002; 324: 23.)
5. Mackenbach JP. Income inequality and population health. BMJ 2002: 324:
1-2.
6. Shi L, et al. Income inequality, primary care, and health indicators. J
Fam Pract 1999; 48: 275-84.
7. Shi L, Starfield B. The effect of primary care physician supply and
income inequality on mortality among Blacks and Whites in US metropolitan
areas. Am J Public Health 2001; 91: 1246-50.
8. Shi L, Starfield B. Primary care, income inequality, and self-rated
health in the US: mixed-level analysis. Int J Health Serv 2000; 30(3): 541
-55.
9. Shi L, Starfield B, Politzer R. Primary care, self-rated health, and
reduction in social disparities in health. Health Serv Res 2002; in press.
Competing interests: No competing interests