Controlling for Socioeconomic Status in Pain Disparities Research: All-Else-Equal Analysis When “All Else” Is Not Equal

Abstract

Despite improvements in the overall health in the United States, gaps in quality of care and health outcomes remain stark for racial minorities ⇓. Racial disparities in the prevalence of pain and pain treatment are consistently reported since early 1990s and these concerning disparities occur across settings and types of pain ⇓. The Institute of Medicine has called for promoting dialogue to improve “the visibility of racial and ethnic disparities in health and health care as a national problem” ⇓. Improving the visibility of this intricate problem first and foremost requires correct application and interpretation of research pertaining to racial disparities in health. Colleagues who conduct pain disparities research would firmly acknowledge that a common, if not the most common, question asked in trying to make sense of racial disparities literature is “did you control for socioeconomic status (SES)?” The question is often based on the assumption that the race effect on disparities is indeed an SES effect (i.e., SES is a confounder). This assumption receives further support from the observation that in some studies the effect of race disappears in a model controlling for SES. When this happens, most conclude that race does not matter in disparities-related outcomes. This commentary illustrates why such an interpretation may be misguided given the complex relationship of race and SES in the United States. We begin with defining the concept of confounders and mediators, we then make a case for why SES in the United States context may be best conceptualized as a mediator of race and health relation, we then apply this understanding to an example from pain disparities literature to illustrate the cautions in interpreting the race effects on pain outcomes when controlling for SES. In general, the statistical control or adjustment implies removing bias or unexplained variability …