ReviewMeasuring inequalities in health: What do we know? What do we need to know?
Introduction
Widespread evidence consistently points towards the existence of a socioeconomic gradient in health outcomes in most western societies. An illustrative example is revealed in Case and Deaton [1], who find that a 20-year-old low-income male, on average, reports to be in similar health as a 60-year-old high-income male in the United States. An open question remains as to whether such evidence is generalisable after controlling for different measures of health, socio-economic status and different inequality measures. More specifically, in the last three decades, robust evidence has set out to prove that different measures of socioeconomic position such as income, job status and education underpin the statistical dispersion of different health outcomes. A fairer distribution of health outcomes is a central policy goal in countries where individuals exhibit a relatively higher aversion to inequalities in health. That is, where equity in health ranks higher in the policy agenda.
The World Health Organisation performance framework, in its World Health Report 2000 [111], states equity as a goal by describing that health systems should ensure “responsiveness to population needs from health care services, which are to be fairly distributed and financed”. The latter calls for lowering (and ideally removing) all existing barriers to health care, most primarily those affecting its financing and generally access to care, and to a lesser extent, preventive programmes. Fairness in health financing is addressed by providing comprehensive coverage and limiting the use of direct payments. Similarly, barriers to health care access are normally circumvented through the implementation of programs that ensure free delivery of health care at the point of use. Finally, prevention is normally promoted through public health programs that communicate information and incentivise healthy behaviours, even though they not always manage to curtail pre-existing unequal conditions. Interventions both in the form of health care programs and health prevention policies have been implemented in almost all western countries, and a wealth of evidence on its effects on health inequalities has been build up. However, is there a consensus on the underlying factors underpinning health inequalities?
Several competing explanations have been set out to explain the sources of health inequalities. Importantly, despite public health system coverage being in place, most studies suggest that significant inequalities in health and health care remain pervasive over time [2], [3]. As we show in this study, similar patterns of inequality in health are found between countries with widely different levels of social protection (see Section 5).
Furthermore, empirical methods to identify and measure the extent of income related dispersion of health status have evolved widely to incorporate advances of regression based decompositions. Finally, given that health is a multidimensional concept, different measures arguably capture different dimensions of health status as a construct. Indeed, in Britain, for instance, it is well acknowledged the so-called widening mortality gap between professional and unskilled manual men (House of Commons Health Committee report [104]). This has motivated policy actions to make sure that future health improvements are shared by the population. However, in order to justify policy actions, the right evidence must be reported. This is the underlying rationale of this study: to assist the debate by attempting organising it and evaluate the state of the art.
This paper aims to discuss what to make of the existing literature on the origins of inequalities in health, focusing on how health inequality is measured primarily by economists. In reviewing the literature, we discuss what we believe is the state of each question examined to then suggest ways forward and some policy implications. Firstly, the sources of a social gradient in health are outlined in Section 2; Section 3 follows with measurement of inequalities in health outcomes; Section 4 discusses data sources; Section 5 covers current evidence; Section 6 develops the health policy context; and Section 7 concludes with ways forward.
Section snippets
Background
Empirical economists and social scientists have developed empirical methods that allow quantifying the degree of inequality in the distribution of health and health care utilisation, so as to compare the degree of inequality over time and space. However, besides broader questions on causality, lie of those identifying with some level of precision which factors give rise to health inequalities. Fig. 1 provides a simple potential diagram that summarises different sources of health inequalities
Measurement
Inequality is in itself a measure of relative dispersion that can be identified visually by comparing extremes on a distribution but that it must confront severe difficulties when it comes to finding ways to compare two societies’ distributions over time and space. One way to measure the dispersion of individuals’ health status on the societal income distribution, implies exploring income-related inequality indices over time and over different health dimensions. This information is a key tenet
Measuring health
When analysing equity in outcomes at the individual level, different health outcome measures have been used in the literature, ranging from subjective measures of health such as self-assessed health (e.g., [42]) and quasi-objective indicators of health status such as the SF-36 physical functioning score (e.g., [43], [44]), indicators of specific illnesses such as coronary heart disease (e.g., [45]), limiting longstanding illness (e.g., [46]), BMI (e.g., [106]), and mental health problems [47],
What do we know?
Several cross-country studies for European countries have provided evidence of inequalities in health outcomes, with a focus on whether disparities in health outcomes differ systematically according to socioeconomic variables, such as education or income.
Large and persistent education-related inequalities in self-assessed health have been observed at the European level [84]. Although decreasing with age, education-related inequalities have been found in Europe in common chronic diseases: high
Inequalities in health in the policy agenda
There is a global and growing concern for reducing socioeconomic inequalities in health in the policy agenda. This is the case of the European Union Member States, which face an aging population and a rapid increase in unemployment as well as an economic downturn. Similarly, international organisations such as the World Health Organisation have played an important role in providing a framework and the principles to encourage action in many countries.
While there is heterogeneity in the way
What should we know?
Studies in western countries exhibit some consensus around the fact that certain inequalities are persistent over time [54]. This finding indicates that policy economists and health policy scholars need to develop further theory and evidence on what the underlying sources of health inequalities are.
In explaining health inequalities one potential hypothesis is that inequalities reflect differences in attitudes towards health distribution, which in turn explains why limited policy action takes
Acknowledgements
Authors are grateful to Stephen Jenkins, Beatriz Gonzalez Lopez-Valcarcel and two anonymous referees for their comments and suggestions.
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