The association of neighborhood racial mix and ED visit count in a cohort of patients on hemodialysis

The association of health outcomes with neighborhood residence has long been described as an important manifestation of racial segregation in the US [1‐5]. Disparities in access to optimal healthcare services are cited as reasons for poor health outcomes, while other reasons relate to lack of neighborhood resources to support healthy habits and diets, exposure to crime and environmental toxins, and limited access to high quality outpatient care coordination [1, 5]. Whether these disparities are related to socioeconomic disadvantages in predominantly Black or Hispanic neighborhoods, institutional/structural racism inherent in political and social systems, and/or local healthcare practices is a point of controversy [5‐9]. It is difficult to separate socioeconomic disadvantage from the racial/ethnic makeup of most metropolitan neighborhoods. Therefore, socioeconomic and race/ethnicity factors as they relate to health outcomes are frequently clumped together [1, 4].

Neighborhood characteristics determine health outcomes in the end-stage kidney disease (ESKD) population as well [8, 10‐15]. Black and White patients that receive care in dialysis facilities located in neighborhoods with a higher percentage of Black residents are less likely to meet performance benchmarks as defined by the Centers for Medicare Services (CMS) [16]. Furthermore, there are higher rates of hospitalizations in patients from dialysis facilities located in areas with a higher percentage of Black residents [16]. Black patients have lower rates of access to pre-ESKD care by a nephrologist, are less likely to have a fistula as the first dialysis access, and have lower rates of referral to transplant centers, which explains some of these outcomes [16, 17]. This is of particular interest because despite these disadvantages, Black patients on hemodialysis have longer adjusted survival time as compared to Whites [16, 18‐20]. CMS had proposed adjusting for case mix based on neighborhood characteristics when calculating benchmarks for standardized readmission ratios as part of the quality incentive program. However, when adjusted for a composite neighborhood score (ADI: area deprivation index) the readmission rates studied by CMS were not altered to a degree that they felt warranted altering the existing case mix formula and as a result, neighborhood characteristics were left out of benchmark determinations [21].

In this study, we explore the association of neighborhood racial/ethnic make-up, with subjects’ residence as the locus for the census block group, with emergency department (ED) visits in a cohort of patients on hemodialysis that live in the Bronx. We hypothesize that the neighborhood racial/ethnic makeup alone, independent of socio-economic status, is not associated with ED visits. To reduce residual confounding we did a separate analysis, wherein we evaluated the association of neighborhood racial/ethnic make-up with dialysis facility characteristics.

The study was approved by the Albert Einstein Institutional Review Board. We adhered to the Declaration of Helsinki in our methods.

Our study of a cohort of patients on hemodialysis who had at least one ED visit to a large hospital system showed a median IRR of 3 repeat ED visits during the study period. Living in block groups in the highest quintiles of percent Black residents was associated with an IRR of 4 avoidable ED visits. Hispanic and White subjects that lived in areas with the highest percentage of Black residents had higher IRR of avoidable ED visits than the Black residents, as did male patients on hemodialysis living in areas with the highest percentage of Black residents as compared to female patients. We found that being younger, a non-English speaker, and having a history of heart failure (most likely a proxy for episodes of fluid overload) are also significantly associated with ED visit rates. These results are consistent with other studies in the literature [30, 31]. The IRR for ED visits in our study is comparable to national rates, and the differential risks defined by neighborhood of residence is consistent with associations reported between neighborhood of residence and hospitalization outcomes in the ESKD population [4, 5, 27].

The history of racial segregation in America has led to the establishment of what we know today as residentially segregated metropolitan areas and was driven historically by systematic exclusion of Blacks from the two of the most generous and foundational programs for creating wealth and opportunity in the nation, the Homeowners’ Loan Act of 1933 which created the Home Owners Loan Corporation (HOLC) and the Servicemen’s Readjustment Act of 1944 or GI Bill which supported housing and education [32]. The persistent exclusion beyond civil rights legislation through exclusionary policies and/or practices have maintained segregation and perpetuated socioeconomic and other structural disparities that disproportionately affect predominantly Black neighborhoods [32]. Some contributors to neighborhood level health disparities are high crime rates, limited mobility, low quality schools, sub-standard housing, few recreational facilities and lack of wholesome food options, all of which are compounded by the constant financial and psychological stress of a lower class lifestyle [1]. Patients with ESKD are disproportionately clustered in large metropolitan, predominantly black neighborhoods [15].

An analysis by Rodriguez et al. found White and Black patients on hemodialysis that lived in predominantly Black neighborhoods had worse quality dialysis and longer times to transplant as compared to those who resided in zip codes with lower percentage of Blacks [16]. The mortality rates were higher in the White patients that lived in predominantly Black neighborhoods, as compared to Black patients [16]. Yan et al. showed lowest pre-ESKD nephrology care and arterio-venous fistula placement for young Blacks in metropolitan areas [17]. Within the first year of starting hemodialysis, adjusted cardiovascular and infection related hospitalizations were higher in younger Black and Hispanic patients [33]. In these studies, those neighborhoods with a higher percentage of Black residents also had lower median incomes, a higher percentage of families living under the poverty line and a lower percentage of residents with high school diplomas [3, 16, 33]. By contrast, our analysis of those block groups in the Bronx with the higher percentage of Black residents found fewer families living under the poverty line and with a higher percentage of residents having graduated high school. Our observations highlight demographic differences within racially clustered communities but also across different geographic areas. The finding that despite higher SES those living in predominantly Black neighborhoods had higher ED visit counts could be due to distrust of the medical establishment that has been reported to influence patients’ beliefs and behaviors for seeking and/or receiving appropriate care, and ability to achieve equitable clinical outcomes [34, 35]. Another factor could be stereotype threat, a more recently recognized concept in healthcare, that refers to the fear of being judged by, and/or of personally confirming through one’s own actions, negative group stereotypes that specifically operate within the domain of healthcare, such as inferior intelligence, lower status, and being less deserving of the highest standard of care, and has been identified to operate in older African Americans [36]. Furthermore, the finding that White and Hispanic patients from neighborhoods with a higher percentage of Black residents were at an even higher risk for avoidable ED visits than Black patients is consistent with social theories that explain the disproportionately bad health outcomes in these populations: positing that Whites and Hispanics who reside in predominantly Black neighborhoods are even more vulnerable than their Black counterparts [5]. Our finding that male patients on hemodialysis are at higher risk for avoidable ED visits in those neighborhoods with a higher percentage of Black residents supports prior data that shows that young Black men are less likely to access primary care and that those on hemodialysis are at higher risk for mortality than their counterparts [10, 37, 38] (Fig. 2).

Limitations of our study include the retrospective nature of the analysis, missing data for some of the clinical variables, as well as the lack of data with respect to dialysis vintage, although there is no reason to suspect that these phenomena should introduce differential bias into the interpretation of results that are based on neighborhood racial makeup. Our cohort excluded patients that never made an ED visit over the study period but previous work shows a high rate of ED visits in this population, therefore we feel comfortable that our sample represents most of the hemodialysis population served by our hospitals [22]. Though Montefiore is the predominant hospital in the Bronx and the fidelity of patients to the location of their recurrent ED visits is high, there is a possibility that a number of patients made ED visits to other hospitals in the Bronx and thus were not taken into account. This may introduce differential bias because two of the non-Montefiore hospitals are located in the South Bronx, which has a significantly socioeconomically disadvantaged population, by Bronx standards. However, because of the lower geographic variation in access to care and the availability of outpatient services by the one hospital system studied, residual confounding related to these variables is minimized. Finally we were unable to capture the laboratory data routinely collected at the outpatient dialysis facilities which would have been helpful in interpreting some of this data. Strengths of our analysis included minimal residual confounding related to differences in geographic access to care, hospital related services, and chronic illnesses requiring repeat hospitalizations (as we chose ED visits, with more of an emphasis on patient behavior, family/social support and care coordination, than hospitalizations).

In conclusion, our study of a cohort of patients on hemodialysis in the Bronx shows that living in a neighborhood with a higher percentage of Blacks is associated with repeat ED visits, especially in males and non-Black patients (Hispanic and White). The implications of these findings support the role of structural and institutional barriers to effective outpatient care for the ESKD population and the fact that they disproportionately affect males living in predominantly Black neighborhoods. In order to mitigate inpatient resource utilization, attention should be paid to upstream barriers to effective outpatient care in predominantly Black neighborhoods and recognize that this affects patients of all backgrounds that live in these communities.