Rurality of patient residence and access to transplantation among children with kidney failure in the United States.

BACKGROUND: Residence in rural areas is often a barrier to health care access. To date, differences in access to kidney transplantation among children who reside in rural and micropolitan areas of the US have not been explored. METHODS: A retrospective cohort study of children < 18 years who developed kidney failure between 2000 and 2019 according to the United States Renal Data System (USRDS). We examined the association between rurality of patient residence and time to living and/or deceased donor kidney transplantation (primary outcomes) and waitlist registration (secondary outcome) using Fine-Gray models. RESULTS: We included 18,530 children, of whom 14,175 (76.5%) received a kidney transplant (39.8% from a living and 60.2% from a deceased donor). Residence in micropolitan (subhazard ratio (SHR) 1.16; 95% CI 1.06-1.27) and rural (SHR 1.18; 95% CI 1.06-1.3) areas was associated with better access to living donor transplantation compared with residence in metropolitan areas. There was no statistically significant association between residence in micropolitan (SHR, 0.95; 95%CI 0.88-1.03) and rural (SHR, 0.94; 95%CI 0.86-1.03) areas compared with metropolitan areas in the access of children to deceased donor transplantation. There was also no difference in the time to waitlist registration comparing micropolitan (SHR 1.04; 95%CI 0.98-1.10) and rural (SHR 1.05; 95% CI 0.98-1.13) versus metropolitan areas. CONCLUSIONS: In children with kidney failure, residence in rural and micropolitan areas was associated with better access to living donor transplantation and similar access to deceased donor transplantation compared with residence in metropolitan areas.

Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk.

Our Galaxy is thought to have an active evolutionary history, dominated over the past ten billion years or so by star formation, the accretion of cold gas and, in particular, the merging of clumps of baryonic and dark matter. The stellar halo-the faint, roughly spherical component of the Galaxy-reveals rich 'fossil' evidence of these interactions, in the form of stellar streams, substructures and chemically distinct stellar components. The effects of interactions with dwarf galaxies on the content and morphology of the Galactic disk are still being explored. Recent studies have identified kinematically distinct stellar substructures and moving groups of stars in our Galaxy, which may have extragalactic origins. There is also mounting evidence that stellar overdensities (regions with greater-than-average stellar density) at the interface between the outer disk and the halo could have been caused by the interaction of a dwarf galaxy with the disk. Here we report a spectroscopic analysis of 14 stars from two stellar overdensities, each lying about five kiloparsecs above or below the Galactic plane-locations suggestive of an association with the stellar halo. We find that the chemical compositions of these two groups of stars are almost identical, both within and between these overdensities, and closely match the abundance patterns of stars in the Galactic disk. We conclude that these stars came from the disk, and that the overdensities that they are part of were created by tidal interactions of the disk with passing or merging dwarf galaxies.

Kidney transplant candidacy evaluation and waitlisting practices in the United States and their association with access to transplantation.

There are limited data on the degree of variability in practices surrounding prioritization of referrals for transplant evaluation and criteria for transplant candidacy and their association with transplantation rates. We surveyed transplant programs across the United States between January 2020 and May 2020 to determine current pre-transplantation practices. We examined the relation between these reported practices and the outcomes of waitlisted patients at responding programs between January 2015 and March 2021 using Scientific Registry of Transplant Recipients data. We used adjusted Cox models with random effects to accommodate clustering by program. Primary outcomes included living or deceased donor transplantation. Of 172 surveyed programs, 90 participated. Substantial variations were noted in when the candidacy evaluation began (13% reported when eGFR was <30 mL/min/1.73 m2 and 17% reported no set policy) and the approach to pre-transplantation cardiac workup (multi-modality [58%], stress echocardiogram [20%]). Using adjusted models, a program policy of using other measures of body habitus to determine transplant candidacy rather than requiring patients to meet a body mass index (BMI) threshold of ≤35 kg/m2 (reference group) for candidacy was associated with a higher hazard of living donor transplantation (HR 1.83 [95% CI 1.10-3.03]). Pre-transplant practices vary substantially across the United States, and select practices were associated with transplantation rates.

Association between Longer Travel Distance for Transplant Care and Access to Kidney Transplantation and Graft Survival in the United States.

BACKGROUND: Transplant candidates may gain an advantage by traveling to receive care at a transplant center that may have more favorable characteristics than their local center. Factors associated with longer travel distance for transplant care and whether the excess travel distance (ETD) is associated with access to transplantation or with graft failure are unknown. METHODS: This study of adults in the United States wait-listed for kidney transplantation in 1995-2015 used ETD, defined as distance a patient traveled beyond the nearest transplant center for initial waiting list registration. We used linear regression to examine patient and center characteristics associated with ETD and Fine-Gray models to examine the association between ETD (modeled as a spline) and time to deceased or living donor transplantation or graft failure. RESULTS: Of 373,365 patients, 11% had an ETD≥50 miles. Traveling excess distance was more likely among patients who were of non-Black race or those whose nearest transplant center had lower annual living donor transplant volume. At an ETD of 50 miles, we observed a lower likelihood of deceased donor transplantation (subhazard ratio [SHR], 0.85; 95% confidence interval [95% CI], 0.84 to 0.87) but higher likelihood of living donor transplantation (SHR, 1.14; 95% CI, 1.12 to 1.16) compared with those who received care at their nearest center. ETD was weakly associated with higher risk of graft failure. CONCLUSIONS: Patients who travel excess distances for transplant care have better access to living donor but not deceased donor transplantation and slightly higher risk of graft failure. Traveling excess distances is not clearly associated with better outcomes, especially if living donors are unavailable.

Longer Distance From Dialysis Facility to Transplant Center Is Associated With Lower Access to Kidney Transplantation.

Rates of kidney transplantation vary substantially across dialysis facilities in the United States. Whether distance between the dialysis facility and transplant center associates with variations in transplantation rates has not been examined. METHODS: We performed a retrospective study of adults treated with dialysis between 2005 and 2015, according to the US Renal Data System. We examined the association between distance from dialysis facility to transplant center and time to kidney transplantation (primary outcome) and waitlist registration (secondary outcome) using Fine-Gray models. We also performed sensitivity analyses using the distance from each patient's dialysis facility to the nearest transplant center as the predictor so that patients who were never registered on the waitlist (and therefore would not have a transplant center) could be included. RESULTS: In total, 178 885 waitlisted patients were included for our primary analysis. As distance between dialysis facility and transplant center increased, lower hazard of transplantation (subhazard ratio [HR], 0.92; 95% confidence interval [CI], 0.91-0.94, if distance was 10 to <50 miles; sub-HR, 0.90; 95% CI, 0.88-0.92, if distance ≥50 miles compared with <10 miles) was noted. We also found a weak association between longer distance and hazard of waitlist registration (sub-HR, 0.96; 95% CI, 0.94-0.97, if distance was ≥50 miles versus <10 miles). Findings were similar in sensitivity analyses using distance between dialysis facility and the nearest transplant center (N = 1 149 721). CONCLUSIONS: Patients receiving dialysis in facilities located further away from transplant centers have lower hazard of kidney transplantation. Developing strategies to address barriers to transplantation in patients receiving dialysis at facilities located far away from a transplant center may help improve disparities in transplantation rates.

Weighing the waitlist: Weight changes and access to kidney transplantation among obese candidates.

High body mass index is a known barrier to access to kidney transplantation in patients with end-stage kidney disease. The extent to which weight and weight changes affect access to transplantation among obese candidates differentially by race/ethnicity has received little attention. We included 10 221 obese patients waitlisted for kidney transplantation prior to end-stage kidney disease onset between 1995-2015. We used multinomial logistic regression models to examine the association between race/ethnicity and annualized change in body mass index (defined as stable [-2 to 2 kg/m2/year], loss [>2 kg/m2/year] or gain [>2 kg/m2/year]). We then used Fine-Gray models to examine the association between weight changes and access to living or deceased donor transplantation by race/ethnicity, accounting for the competing risk of death. Overall, 29% of the cohort lost weight and 7% gained weight; 46% received a transplant. Non-Hispanic blacks had a 24% (95% CI 1.12-1.38) higher odds of weight loss and 22% lower odds of weight gain (95% CI 0.64-0.95) compared with non-Hispanic whites. Hispanics did not differ from whites in their odds of weight loss or weight gain. Overall, weight gain was associated with lower access to transplantation (HR 0.88 [95% CI 0.79-0.99]) compared with maintenance of stable weight, but weight loss was not associated with better access to transplantation (HR 0.96 [95% CI 0.90-1.02]), although this relation differed by baseline body mass index and for recipients of living versus deceased donor organs. For example, weight loss was associated with improved access to living donor transplantation (HR 1.24 [95% CI 1.07-1.44]) in whites but not in blacks or Hispanics. In a cohort of obese patients waitlisted before dialysis, blacks were more likely to lose weight and less likely to gain weight compared with whites. Weight loss was only associated with improved access to living donor transplantation among whites. Further studies are needed to understand the reasons for the observed associations.