Faculty Bibliography

KEY POINTS:Regardless of race and ethnicity, older adults with kidney failure residing in or receiving care at dialysis facilities located in high-segregation neighborhoods were at a 1.63-fold and 1.53-fold higher risk of dementia diagnosis, respectively. Older adults with kidney failure residing in minority-predominant high-segregation neighborhoods had a 2.19-fold higher risk of dementia diagnosis compared with White individuals in White-predominant neighborhoods. BACKGROUND:a form of structural racism recently identified as a mechanism in numerous other health disparities. METHODS:We identified 901,065 older adults (aged ≥55 years) with kidney failure from 2003 to 2019 using the United States Renal Data System. We quantified dementia risk across tertiles of residential neighborhood segregation score using cause-specific hazard models, adjusting for individual- and neighborhood-level factors. We included an interaction term to quantify the differential effect of segregation on dementia diagnosis by race and ethnicity. RESULTS: CONCLUSIONS:Residing in or receiving care at dialysis facilities located in high-segregation neighborhoods was associated with a higher risk of dementia diagnosis among older individuals with kidney failure, particularly minoritized individuals.

OBJECTIVES/OBJECTIVE:Obesogenic medications are a putative contributor to the obesity epidemic. While 20% of adults take ≥1 obesogenic medication, the proportion in the end-stage kidney disease (ESKD) population-a group enriched for cardiometabolic complications-is unknown. Obesogenic medications may contribute to obesity and hamper weight loss efforts to achieve transplant listing. METHODS:Using 2017-2020 USRDS and Medicare claims, patients were identified as taking obesogenic medications if prescribed anticonvulsants, antidepressants, antidiabetics, anti-inflammatories, antipsychotics, and/or antihypertensives known to cause weight gain for ≥30 days in their first hemodialysis year. Ordinal logistic and Cox regression with inverse probability of treatment weighting were used to quantify obesogenic medications' association with body mass index (BMI) and listing, respectively. RESULTS:Among 271 401 hemodialysis initiates, 63.5% took ≥1 obesogenic medication. For those in underweight, normal weight, overweight, and class I, II, and III categories, 54.3%, 58.4%, 63.1%, 66.5%, 68.6%, and 68.8% took ≥1, respectively. Number of obesogenic medications was associated with increased BMI; use of one was associated with 13% increased odds of higher BMI (aOR [adjusted odds ratio] 1.14; 95%CI: 1.13-1.16; p < 0.001), use of three was associated with a 55% increase (aOR 1.55; 95%CI: 1.53-1.57; p < 0.001). Any use was associated with 6% lower odds of transplant listing (aHR [adjusted hazard ratio] 0.94; 95%CI: 0.92-0.96; p < 0.001). Within each BMI category, obesogenic medication use was associated with lower listing likelihood. CONCLUSIONS:Obesogenic medication use is common in ESKD patients-particularly those with obesity-and is associated with lower listing likelihood. Whenever possible, non-obesogenic alternatives should be chosen for ESKD patients attempting weight loss to achieve transplant listing.

BACKGROUND:Prior to kidney transplantation (KT) most patients have an elevated parathyroid hormone (PTH). However, the impact of PTH on post-KT mortality and graft loss is unclear. We quantified the association between PTH levels measured at transplant and adverse post-KT outcomes. STUDY DESIGN/METHODS:A prospective longitudinal cohort of 1,136 KT recipients from a single tertiary care center between 12/2008 and 2/2020. Pre-KT PTH levels were abstracted retrospectively. Adjusted multivariable Cox proportional hazards models were used to estimate the association between pre-KT PTH levels and mortality and death-censored graft loss (DCGL). RESULTS:Of 1,136 recipients, pre-KT PTH levels were ≤300pg/mL in 62.3% and >600pg/mL in 12.5%. Compared to those with a pre-KT PTH≤300pg/mL, patients with a pre-KT PTH>600pg/mL were more likely to be Black (51.4% vs. 34.6%) and have a longer dialysis vintage (4.8y vs. 1.7y) (p<0.001). Those with a pre-KT PTH>600pg/mL had a higher 10-year cumulative incidence of DCGL than those with PTH≤300pg/mL (31.7% vs. 15.4%, p<0.001). After adjusting for confounders, pre-KT PTH>600pg/mL was associated with a 1.76-fold increased risk of DCGL (95% CI: 1.16-2.65). The magnitude of this association differed by race (pinteraction=0.011) and by treatment (pinteraction=0.018). Among non-Black patients, a PTH>600pg/mL was associated with a 3.21-fold increased risk of DCGL compared to those with PTH≤300pg/mL (95%CI: 1.77-5.81). Among untreated patients, those with PTH>600pg/mL had a 2.54-fold increase in DCGL (95%CI: 1.44-4.47). There was no association between pre-KT PTH and mortality risk. CONCLUSIONS:PTH >600pg/mL prior to KT increased the risk of DCGL by 76%, demonstrating the importance of treating PTH prior to KT to prevent graft loss in a contemporary era with the introduction and widespread availability of medical therapy.

RATIONALE & OBJECTIVE/OBJECTIVE:Exposure to extreme heat events has been linked to increased morbidity and mortality in the general population. Patients receiving maintenance dialysis may be vulnerable to greater risks from these events, but this is not well understood. We sought to characterize the association of extreme heat events and the risk of death among patients receiving dialysis in the United States. STUDY DESIGN/METHODS:Retrospective cohort study. SETTING & PARTICIPANTS/METHODS:Data from the United States Renal Data System were used to identify adults living in US urban settlements prone to extreme heat who initiated maintenance dialysis between 1997 and 2016. EXPOSURE/METHODS:An extreme heat event was defined as a time-updated heat index (a humid-heat metric) exceeding 40.6°C for ≥2 days or 46.1°C for ≥1 day. OUTCOME/RESULTS:Death. ANALYTICAL APPROACH/METHODS:Cox proportional hazards regression to estimate the elevation in risk of death during a humid-heat event adjusted for age, sex, year of dialysis initiation, dialysis modality, poverty level, and climate region. Interactions between humid-heat and these same factors were explored. RESULTS:Among 945,251 adults in 245 urban settlements, the mean age was 63 years and 44% were female. During a median follow-up of 3.6 years, 498,049 adults were exposed to at least one of 7,154 extreme humid-heat events, and 500,025 deaths occurred. In adjusted models, there was an increased risk of death (hazard ratio 1.18; 95% confidence interval 1.15-1.20) during extreme humid-heat exposure. Relative mortality risk was higher among patients living in the Southeast (P<0.001) compared with the Southwest. LIMITATIONS/CONCLUSIONS:Possibility of exposure misclassification, did not account for land use and air pollution co-exposures. CONCLUSIONS:This study suggests that patients receiving dialysis face an increased risk of death during extreme humid-heat exposure.

BACKGROUND:Though older adults with chronic kidney disease (CKD) have a greater mortality risk than those without CKD, traditional risk factors poorly predict mortality in this population. Therefore, we tested our hypothesis that two common geriatric risk factors, frailty and cognitive impairment, and their co-occurrence, might improve mortality risk prediction in CKD. METHODS:Among participants aged ≥ 60 years from National Health and Nutrition Examination Survey (2011-2014), we quantified associations between frailty (physical frailty phenotype) and global/domain-specific cognitive function (immediate-recall [CERAD-WL], delayed-recall [CERAD-DL], verbal fluency [AF], executive function/processing speed [DSST], and global [standardized-average of 4 domain-specific tests]) using linear regression, and tested whether associations differed by CKD using a Wald test. We then tested whether frailty, global cognitive impairment (1.5SD below the mean), or their combination improved prediction of mortality (Cox models, c-statistics) compared to base models (likelihood-ratios) among those with and without CKD. RESULTS: < 0.001) but not cognitive impairment. CONCLUSIONS:Frailty is associated with worse cognitive function regardless of CKD status. While CKD and frailty improved mortality prediction, cognitive impairment did not. Risk prediction tools should incorporate frailty to improve mortality prediction among those with CKD.

BACKGROUND:Recent data suggest patients with graft failure had better access to repeat kidney transplantation (re-KT) than transplant-naive dialysis accessing first KT. This was postulated to be because of better familiarity with the transplant process and healthcare system; whether this advantage is equitably distributed is not known. We compared the magnitude of racial/ethnic disparities in access to re-KT versus first KT. METHODS:Using United States Renal Data System, we identified 104 454 White, Black, and Hispanic patients with a history of graft failure from 1995 to 2018, and 2 357 753 transplant-naive dialysis patients. We used adjusted Cox regression to estimate disparities in access to first and re-KT and whether the magnitude of these disparities differed between first and re-KT using a Wald test. RESULTS:Black patients had inferior access to both waitlisting and receiving first KT and re-KT. However, the racial/ethnic disparities in waitlisting for (adjusted hazard ratio [aHR] = 0.77; 95% confidence interval [CI], 0.74-0.80) and receiving re-KT (aHR = 0.61; 95% CI, 0.58-0.64) was greater than the racial/ethnic disparities in first KT (waitlisting: aHR = 0.91; 95% CI, 0.90-0.93; Pinteraction = 0.001; KT: aHR = 0.68; 95% CI, 0.64-0.72; Pinteraction < 0.001). For Hispanic patients, ethnic disparities in waitlisting for re-KT (aHR = 0.83; 95% CI, 0.79-0.88) were greater than for first KT (aHR = 1.14; 95% CI, 1.11-1.16; Pinteraction < 0.001). However, the disparity in receiving re-KT (aHR = 0.76; 95% CI, 0.72-0.80) was similar to that for first KT (aHR = 0.73; 95% CI, 0.68-0.79; Pinteraction = 0.55). Inferences were similar when restricting the cohorts to the Kidney Allocation System era. CONCLUSIONS:Unlike White patients, Black and Hispanic patients with graft failure do not experience improved access to re-KT. This suggests that structural and systemic barriers likely persist for racialized patients accessing re-KT, and systemic changes are needed to achieve transplant equity.

IMPORTANCE/UNASSIGNED:Identifying the mechanisms of structural racism, such as racial and ethnic segregation, is a crucial first step in addressing the persistent disparities in access to live donor kidney transplantation (LDKT). OBJECTIVE/UNASSIGNED:To assess whether segregation at the candidate's residential neighborhood and transplant center neighborhood is associated with access to LDKT. DESIGN, SETTING, AND PARTICIPANTS/UNASSIGNED:In this cohort study spanning January 1995 to December 2021, participants included non-Hispanic Black or White adult candidates for first-time LDKT reported in the US national transplant registry. The median (IQR) follow-up time for each participant was 1.9 (0.6-3.0) years. MAIN OUTCOME AND MEASURES/UNASSIGNED:Segregation, measured using the Theil H method to calculate segregation tertiles in zip code tabulation areas based on the American Community Survey 5-year estimates, reflects the heterogeneity in neighborhood racial and ethnic composition. To quantify the likelihood of LDKT by neighborhood segregation, cause-specific hazard models were adjusted for individual-level and neighborhood-level factors and included an interaction between segregation tertiles and race. RESULTS/UNASSIGNED:Among 162 587 candidates for kidney transplant, the mean (SD) age was 51.6 (13.2) years, 65 141 (40.1%) were female, 80 023 (49.2%) were Black, and 82 564 (50.8%) were White. Among Black candidates, living in a high-segregation neighborhood was associated with 10% (adjusted hazard ratio [AHR], 0.90 [95% CI, 0.84-0.97]) lower access to LDKT relative to residence in low-segregation neighborhoods; no such association was observed among White candidates (P for interaction = .01). Both Black candidates (AHR, 0.94 [95% CI, 0.89-1.00]) and White candidates (AHR, 0.92 [95% CI, 0.88-0.97]) listed at transplant centers in high-segregation neighborhoods had lower access to LDKT relative to their counterparts listed at centers in low-segregation neighborhoods (P for interaction = .64). Within high-segregation transplant center neighborhoods, candidates listed at predominantly minority neighborhoods had 17% lower access to LDKT relative to candidates listed at predominantly White neighborhoods (AHR, 0.83 [95% CI, 0.75-0.92]). Black candidates residing in or listed at transplant centers in predominantly minority neighborhoods had significantly lower likelihood of LDKT relative to White candidates residing in or listed at transplant centers located in predominantly White neighborhoods (65% and 64%, respectively). CONCLUSIONS/UNASSIGNED:Segregated residential and transplant center neighborhoods likely serve as a mechanism of structural racism, contributing to persistent racial disparities in access to LDKT. To promote equitable access, studies should assess targeted interventions (eg, community outreach clinics) to improve support for potential candidates and donors and ultimately mitigate the effects of segregation.