Racial disparities in chronic kidney disease: Need for attention

Chronic kidney disease (CKD) is a global public health problem.[1-3] CKD and, more importantly, end-stage renal disease (ESRD) are characterised by significant differences in incidence, prevalence and complication across gender, age, race/ethnicity, socio-economic status and geographical areas. CKD has been divided into five stages, and an ESRD is based on glomerular filtration rates by the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative.[4] ESRD is a very remarkable example of health disparities amongst minorities ranging from 1.5 to 4 times those of age-adjusted white counterparts[5] despite similar rates for the early stages of CKD.[6] CKD is associated with increased premature death rates.[7,8] Hispanics, one of the fastest-growing racial groups in the United States, are twice as likely to develop kidney failure compared to non-Hispanic whites.[9] The Institute of Medicine (IOM) notes that inequities in health outcomes arise within the healthcare system due to factors such as the operation of healthcare systems, legal or regulatory climate or from ecological factors such as clinical appropriateness and need and patient preferences with significant overlap from discrimination, biases and prejudice. [10,11] The IOM defines disparities in healthcare as differences that generally represent institutional or provider biases that are unjust and may be unintentional.[10,11] The term 'health disparities' is usually used to describe the adverse health outcomes experienced by racial/ethnic minorities that occur in the context of broad historical and present-day social and economic inequality in addition to healthcare system factors. De facto racial segregation is prevalent in US healthcare due to limited resources, both man and material, which constrain organisations working for the poor and minority racial groups.[12] Residential segregation was an earlier federal policy, and it continues as mortgage discrimination. This results in racially divided communities that share low-income status but often differ in wealth, community assets, exposure to heavy metals or excessive ambient particulate matter and other factors that may impact CKD-related outcomes.[13] Geographic analyses revealed that community-level poverty was strongly associated with higher ESRD incidence. This was more so in Black individuals.[14] Dialysis facilities located in predominantly Black communities have higher mortality rates and less compliance with recommended facility performance.[15] It is possible, with a better understanding of health disparities, to think beyond racial and ethnic background as the defined risk for CKD progression and analyse the underlying biological, socio-demographic and cultural factors. One may start considering race and ethnicity as merely surrogates for these factors. An overview of the epidemiology of CKD in racial groups clearly demonstrates that racial/ethnic minorities make up a disproportionate share of the ESRD population. The reasons are multi-factorial. The National Health and Nutrition Examination Survey (NHANES II) and Atherosclerosis Risk In Communities (ARIC) studies suggest that 10%–12% excess risk for CKD is explained by socio-demographic factors such as education, household income and insurance status.[16,17] It is well known that lack of insurance is an important predictor of referral to nephrologists.[18] However, according to a study,[19] uniform healthcare lowers all complications of diabetes mellitus except ESRD. This study[19]conducted over three years in 62,000 ethnically diverse patients with diabetes mellitus suggested that even in a uniform healthcare environment, CKD outcomes are unique compared to other medical conditions.[19] Among the most important clinical and biological risk factors for CKD are hypertension and diabetes mellitus. These risk factors for CKD are more prevalent in many minority populations, possibly explaining some of the disparities in ESRD risk. Demographic and socio-economic factors contributing to early progression include age, sex, lower education, income or health insurance, leading to poor access to appropriate therapies for patients with CKD. It is increasingly recognised that there is an interplay of biological, clinical, socio-demographic and behavioural factors in chronic disease progression and that fundamental research is needed to understand what behaviours can prevent complications and maintain health. With the excess prevalence of biological, clinical and socio-demographic risk factors, racial and ethnic minorities should be targeted for prevention and treatment of risk factors, but studies show that risk factors may be undermanaged compared with their white counterparts. The reasons for undermanagement are complex, involving behaviours of patients, behaviours of providers and interactions between patients and healthcare providers. Chronic disease care can be viewed on the continuum of awareness of the disease, treatment of the condition and control of the condition. This paradigm has been used to assess hypertension treatment and can be applied to other chronic diseases. Having a regular healthcare provider could promote awareness of an asymptomatic disease, taking appropriate medications and, finally, control of the disease. The full scope of behavioural factors that could impact on chronic disease is health knowledge and awareness of disease, beliefs and attitudes and dietary or lifestyle habits; language and health literacy; patient–physician communication;[20] participatory decision-making by providers;[21,22] trust in physicians and the healthcare system;[23,24] patient perceptions of respectful treatment by healthcare providers[25] and patient adherence to recommended therapies.[26,27] Few of these factors have been explored for their contribution to disparities in CKD. The prevalence of anaemia is more in all stages of CKD in non-Hispanic whites, but the use of erythropoietin is different between the races and lower in minorities because it correlates with referral to nephrologists. Similarly, bone mineral disorders related to CKD and placement of vascular access in ESRD are all less in the Black CKD population. Early referral to nephrologists lowers mortality.[28] However, as mentioned earlier, it is lower in Blacks. Renal therapy choice – Peritoneal dialysis is less in non-Hispanic Blacks.[29] Similarly, listing for transplantation and getting the transplantation are less in minorities compared to counterparts.[30] The barriers contributing to disparities are mainly defined in renal transplantation[31] but are also applicable to other areas. They are patient[32] related and physician related.[33] Patient-related barriers are thoughts of racial discrimination and attitudes. Physician-related barriers are opinions attributed to patient factors such as poor survival, patient–doctor communication, lack of trust, physician bias and maybe more.[34] Are the disparities being because of disproportionate differences in the increase of risk factors for CKD between the races? Just because of increased incident rates in certain races? Is it because of the aggressive progression of this disease in certain races? Is it exclusively and entirely a result of the genetic basis for racial differences? Is it because of high mortality in some races and the resultant lower numbers in those races? It is important to note and make necessary changes that many public datasets, including NHANES, are mostly cross-sectional and not longitudinal. They prevent the assessment of the temporal relation of risk factors to CKD. It is not possible to say what the cause is and what the result of this cause is. This prevents the appropriate addressing of several issues. Race and socio-economic status are not properly assessed. The attributes of race are not properly defined and used. Socio-economic status is not defined in a uniform and comparable manner across studies. There is a need to develop the datasets while keeping these insights in mind. The incorporation of appropriate variables such as race and socio-economic status into the datasets is essential. Then, multilevel analyses[35] should be used regularly and routinely. Finally, there are racial disparities in CKD, but the causes and factors are not well explored, and barriers are not fully recognised. It may be relevant to mention here that the use of the new 2021 Chronic Kidney Disease Epidemiology Collaboration estimated glomerular filtration rate equation to estimate eGFR without race-based adjustment[36] is believed to reduce racial inequities and might improve the health benefits of Black patients. In retrospect, it appears that the earlier practice of race adjustment has shown a better eGFR as compared to real eGFR causing a delay in referral and contributing for the disparity. However, this remains the priority, and a multipronged attack would reduce or eliminate the disparities soon. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.