Elsevier

The Lancet

Volume 397, Issue 10276, 27 February–5 March 2021, Pages 828-838
The Lancet

Health Policy
The inverse care law re-examined: a global perspective

https://doi.org/10.1016/S0140-6736(21)00243-9Get rights and content

Summary

An inverse care law persists in almost all low-income and middle-income countries, whereby socially disadvantaged people receive less, and lower-quality, health care despite having greater need. By contrast, a disproportionate care law persists in high-income countries, whereby socially disadvantaged people receive more health care, but of worse quality and insufficient quantity to meet their additional needs. Both laws are caused not only by financial barriers and fragmented health insurance systems but also by social inequalities in care seeking and co-investment as well as the costs and benefits of health care. Investing in more integrated universal health coverage and stronger primary care, delivered in proportion to need, can improve population health and reduce health inequality. However, trade-offs sometimes exist between health policy objectives. Health-care technologies, policies, and resourcing should be subjected to distributional analysis of their equity impacts, to ensure the objective of reducing health inequalities is kept in sight.

Introduction

Tudor Hart coined the term inverse care law (ICL)1 in 1971 to describe the double injustice that socially disadvantaged people not only tend to be more susceptible to illness than socially advantaged people but also receive less health care.2, 3, 4, 5 He also noted that social class inequalities in primary care delivery in the UK had been substantially reduced but not eliminated by the introduction of the universal, tax-funded National Health Service (NHS) in 1948.5, 6, 7 The term has since been widely adopted to describe social inequalities or disparities in health care of all kinds, with similar discussions in other countries,8 and similar phrases have been applied to related phenomena, including the “inverse equity hypothesis” (ie, new health interventions are adopted earlier by advantaged populations, thereby initially increasing inequalities)9, 10 and the “inverse hazard law” (ie, health risks vary inversely with wealth and power).11 The original article has been cited by more than 3500 academic publications, mostly by authors outside the UK, and the annual citation rate continues to rise, with an exponential growth in the general academic literature on health-care inequalities (see appendix 1 pp 3–12).

Our aim in this Health Policy is to re-examine the nature, magnitude, and causes of social inequality of health-care delivery from a global perspective in the light of advances in scientific knowledge since 1971. Heterogeneous reporting makes it hard to compare the magnitude of health-care inequality between studies, and cross-country studies still tend to focus on inequality in health-care utilisation rather than the quality of care. However, in this Health Policy, we make cross-country comparisons of the magnitude of inequality in health-care utilisation among high-income countries and, separately, among low-income and middle-income countries; and we summarise the substantial body of knowledge about the causes of health-care inequality from country-specific studies.

Since 1971, little global progress has been made in tackling the ICL. A complete ICL—defined as a decrease in health-care use with social disadvantage—persists in almost all low-income and middle-income countries. A disproportionate ICL—defined as an increase in health-care use with social disadvantage but not in proportion to need—persists even in upper-middle and high-income countries with integrated systems of universal health coverage. The complete ICL is largely driven by financial barriers to health care in unregulated health-care markets, and countries with worse governance tend to have larger ICLs. These barriers, and the inequalities associated with them, are reduced under integrated systems of universal health care. However, social inequalities in health-care quality and outcomes persist due to social inequalities in the ability to seek health care (eg, by taking time off work, navigating complex systems, and avoiding discrimination), the ability to benefit from health care (eg, by investing time and resources in following treatment regimens), and the costs and risks of health care (eg, due to multimorbidity and medical workforce shortages).

Section snippets

The ICL reformulated

The ICL was originally formulated as follows: “The availability of good medical care tends to vary inversely with the need for it in the population served. This ICL operates more completely where health care is more exposed to market forces, and less so where such exposure is reduced.”1 This memorable phrase, punning on inverse square laws from the natural sciences, is an effective communication device that captures imaginations and resonates with people's experiences. However, the ICL needs to

Cross-country comparisons of social inequality in health-care delivery

Social inequalities in health-care delivery are ubiquitous and studies have documented ICLs and DCLs using diverse measures of health-care quantity (eg, doctors, utilisation, expenditure), quality (eg, patient-reported experiences, clinical processes, risk-adjusted outcomes) and social disadvantage (eg, income, occupational class, education, ethnicity, and gender) at various levels of analysis including geographical (eg, neighbourhood, city, region), organisational (eg, family practice,

The causes of social inequality in health-care delivery

The table lists the main proximal causes of social inequality in health-care delivery within countries. There are also distal causes of the causes—in particular poor governance and inequalities in wealth, power, human capital, and the conditions of human life—which frustrate efforts to tackle social inequalities in health care. There is a clear cross-country correlation between the magnitude of health-care inequality in low-income and middle-income countries and the quality of governance as

Discussion

A complete ICL continues to operate in almost all low-income and middle-income countries—ie, health-care workforce, utilisation, and expenditure per capita are inversely related to social disadvantage—although the magnitude varies considerably. By contrast, an incomplete ICL operates in all upper-middle-income and high-income countries with integrated systems of universal health coverage, although again the magnitude varies substantially. In these countries, absolute health-care expenditure is

Acknowledgments

RC, TD, and FPM are supported by the Wellcome Trust (grant number 205427/Z/16/Z). For helpful comments we would like to thank Mark Ashworth, Rama Baru, Chris Bentley, Callum Brindley, Kevin Fiscella, Robert Fleetcroft, John Ford, Peter Goldblatt, Hugh Gravelle, Davidson Gwatkin, Elaine Kelly, Julian Le Grand, Ajay Mahal, Owen O'Donnell, Trevor Sheldon, Peter Smith, Cesar Victora, Elizabeth Walton, and Margaret Whitehead. Any errors or opinions expressed in this publication are those of the

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