Volume 128, March 2015, Pages 316–326
Review
Income inequality and health: A causal review
Highlights
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- Evidence that income inequality is associated with worse health is reviewed.
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- It meets established epidemiological and other scientific criteria for causality.
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- The causal processes may extend to violence and other problems with social gradients.
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- Reducing income inequality will improve population health and wellbeing.
Abstract
There
is a very large literature examining income inequality in relation to
health. Early reviews came to different interpretations of the evidence,
though a large majority of studies reported that health tended to be
worse in more unequal societies. More recent studies, not included in
those reviews, provide substantial new evidence. Our purpose in this
paper is to assess whether or not wider income differences play a causal
role leading to worse health. We conducted a literature review within
an epidemiological causal framework and inferred the likelihood of a
causal relationship between income inequality and health (including
violence) by considering the evidence as a whole. The body of evidence
strongly suggests that income inequality affects population health and
wellbeing. The major causal criteria of temporality, biological
plausibility, consistency and lack of alternative explanations are well
supported. Of the small minority of studies which find no association,
most can be explained by income inequality being measured at an
inappropriate scale, the inclusion of mediating variables as controls,
the use of subjective rather than objective measures of health, or
follow up periods which are too short.
The
evidence that large income differences have damaging health and social
consequences is strong and in most countries inequality is increasing.
Narrowing the gap will improve the health and wellbeing of populations.
Keywords
- Income distribution;
- Review;
- Population health;
- Causality
- Corresponding author. Department of Health Sciences, Seebohm Rowntree Building, Area 3, University of York, Heslington, York, YO10 5DD, UK.
