The multiple ways of defining and measuring disparities make it difficult to synthesize research on disparities and health equity. In a 2012 report by the IOM, one of the recommendations was to standardize the definition of disparities (IOM 2012). A seminal paper by Braverman (2006) provides a history of definitions and measures beginning with Whitehead’s (1992) notion that disparities in health are differences that are avoidable, unjust and unfair. While other authors define any difference in health outcomes as a disparity (Murray, et. al 1999), most incorporate the concept that disparities are due to a disadvantage of one kind or another, e.g. discrimination, place of residence, etc. Because inequity is a result of disadvantage, if one employs Whitehead’s interpretation of disparities, they are avoidable and unjust.
Because it is not always possible to identify differences that are unjust, simple differences by race, ethnicity and other variables such as disability status have been used historically to explore disparities. Many disparities researchers focus their research exclusively on differences by race and ethnicity. In addition, a considerable body of evidence exists on gender disparities. More recently, researchers have also stratified results by socioeconomic status, level of education, geographic region, disability, and sexual preference and orientation. There is tremendous overlap among categories like minority groups, the disabled, low educational attainment, dual-eligibles (Medicaid and Medicare eligible beneficiaries), poverty level, and zip code. With growing discussion of race as a social construct rather than a biological characteristic, measurement of race and ethnicity1 becomes increasingly complicated. Alternative variables that are associated with health outcomes, like zip code and education level, are becoming more attractive to health researchers who wish to move away from using race and ethnicity categories that can lead to stigmatization, discrimination and profiling. The new variables may be more precise in identifying disparities without the negative connotations.
The HHS Action Plan to Reduce Racial and Ethnic Health Disparities (2011) included explanatory information on the many factors that affect health outcomes, as follows, “the World Health Organization (WHO) defines these ‘social determinants of health’ as the conditions in which people are born, grow, live, work and age that can contribute to or detract from the health of individuals and communities. Marked difference in social determinants, such as poverty, low socioeconomic status (SES), and lack of access to care, exist along racial and ethnic lines. These differences can contribute to poor health outcomes” (p. 3). The social determinants of health illustrate how the health care system alone cannot address all health disparities.
A recent National Institute on Aging (NIA) Council report urged the adoption of an integrative conceptual model to approach health disparities research, which conveys that health disparities are multidimensional, and are caused by factors operating at various levels of analysis, including the biological, behavioral, sociocultural, and environmental. The report urges the NIA to identify which factors are important to examine and how various dimensions or factors leading to health disparities interact. It further states that these interactions are important, because the biological factors underlying health disparities are not independent of socioeconomic factors, and health disparities will not be understood simply by focusing on one level of analysis.
While the definitions above convey a nuanced understanding of what causes disparities and how disparities should ideally be studied, to-date most research on disparities in the MCC population has primarily utilized demographic variables to identify differences between groups.
Given the sparse literature specifically focused on MCC disparities, for the purpose of the paper we define disparities as any observed difference in health care quality or health outcomes between population groups characterized by sociodemographic variables such as by race, ethnicity, gender, and socioeconomic status. This broad definition allows us to cast a wide net in identifying relevant research.
1 Race is defined as the biological differences among groups, while ethnicity is defined as a common cultural identity in a group (Cunningham, 2012).