To the Editor The recently published retrospective analysis by Zarkowsky et al1 not only describes an observed racial/ethnic disparity in the care of patients with end-stage renal disease but also calls attention to an important issue regarding race and ethnicity as reported in large databases. Race and ethnicity are fluid, constantly changing categories meant to describe groups of people with a common background. Both are commonly used in the medical literature as a proxy for unmeasured confounders, but they are poorly correlated with socioeconomic status and other social determinants of disease.2 Because defining race and ethnicity is difficult, and because it is the focus of many studies on health care disparities, it is important to clearly understand the definitions used in a study.
Adler JT, Yeh H. Identification of Race and Ethnicity in Large Databases. JAMA Surg. 2015;150(11):1099. doi:10.1001/jamasurg.2015.2228