Both clinical epidemiology and population health perspectives can define the role of health care in reducing health disparities

Abstract

Objective

To compare and contrast clinical epidemiology and population health perspectives on the role of health care in reducing socioeconomic disparities in health.

Study Design and Setting

A review of concepts outlined in selected articles on population health and clinical epidemiology and a systematic literature search for randomized controlled trials (RCTs) of therapeutic interventions for cardiovascular disease that contained analysis of outcomes by socioeconomic status.

Results

Population health has a focus on health disparities, particularly disparities related to socioeconomic status, and many of its proponents have a pessimistic view of the degree to which health care can reduce these disparities. Clinical epidemiology has a focus on the production of valid evidence on the impact of health care interventions; however, RCTs rarely report the impact of interventions across socioeconomic strata. Both population health and clinical epidemiology share the view that efficacy, effectiveness, and cost-effectiveness are all important in defining the impact of health care on health disparities.

Conclusion

Principles drawn from both population health and clinical epidemiology could be used to provide a clearer picture of the role that health care interventions can have on socioeconomic disparities in health and to identify implications for policy, research, and clinical practice.

Introduction

It has long been recognized that there is an association between socioeconomic status and the health of individuals. More specifically, it has been shown that individuals in lower socioeconomic strata have higher mortality rates and poorer health than those in higher strata [1]. This difference in health across socioeconomic strata is not merely a historical curiosity, nor is it limited to nations that lag behind others in political or economic development; it is found in technologically advanced, wealthy, democratic countries. The observation that there is a difference in health not just between the lowest social class and the rest of society, but that each social stratum has a higher mortality than the group above it, leads to the notion of a wealth–health gradient. This gradient has perhaps most famously been shown in a study conducted by Marmot et al. [2] among steadily employed, well-paid British civil servants. The same wealth–health gradient is found in other countries. For example, middle-class families in the United States earning $30,000 to $50,000 a year in 1993 have almost 60% greater mortality than those in the highest income category, and in Canada there are smaller but still substantial mortality differences between the middle class and the wealthiest [3].

The continued existence of disparities in health across the socioeconomic spectrum in developed countries has led Marmot to conclude that “the problem for rich countries today is inequality of health rather than poverty and health” [3]. A key issue faced by policy makers in developing strategies to reduce health disparities is the choice between investing in health care or in strategies designed to reduce socioeconomic differences such as education or income redistribution [4].

Here we will briefly outline the way in which proponents of population health (a paradigm that has a specific focus on studying health disparities) and clinical epidemiology (a paradigm that has a specific focus on studying health care interventions) view the impact of health care on health disparities. We will then identify similarities and differences in these views and outline some implications for research, policy and clinical practice.