Post-kidney transplant body mass index trajectories are associated with graft loss and mortality

Combined Body Mass Index and Body Surface Area to Predict Post Kidney Transplant Outcomes in Patients With Obesity

Background

The prevalence of obesity is increasing in both the general and kidney failure populations. Severe obesity (body mass index [BMI] ≥ 40 kg/m2) is considered by many centers to be a barrier to kidney transplantation (KT). Obesity is typically defined using BMI. Body surface area (BSA) is not considered, though may also be important.

Methods

We examined post-KT adverse outcomes associated with obesity defined using combined BMI-BSA parameters in a cohort of adult KT recipients (living/deceased donor) across the United States (Scientific Registry of Transplant Recipients: 2000-2017). Recipient obesity was defined as BMI ≥30 kg/m2, or BSA ≥1.94 m2 in women and ≥2.17 m2 in men. We used multivariable cox proportional hazards or logistic regression models as appropriate to assess the association between BMI-BSA-defined obesity with death-censored graft loss, all-cause graft loss, and delayed graft function.

Results

The final study included 242 432 patients; 77 556 (32.0%) had obesity based on BMI and 67 312 (28.6%) had obesity based on BSA. Compared to patients with a nonobese BMI and BSA, the adjusted risk of death-censored graft loss, all-cause graft loss, and delayed graft function was greatest when both BMI and BSA indicated obesity (adjusted hazard ratio 1.23, 95% confidence interval [CI]: 1.20-1.27, adjusted hazard ratio 1.09, 95% CI: 1.07-1.11, adjusted odds ratio 1.58, 95% CI: 1.53-1.63, respectively); a significantly greater risk than when BMI and BSA were discordant.

Conclusions

Currently only BMI is considered when evaluating obesity-related KT risk; however, combined BMI-BSA obesity may better identify individuals at high risk of poor outcomes posttransplant than BMI alone.

Impact of weight change on kidney transplantation outcomes: A systematic review and meta-analysis

BACKGROUND AND AIM

Kidney transplant recipients frequently experience a wide range of metabolic complications, including weight changes, which significantly impact patient outcomes and graft function, yet the relationship between weight gain and transplant outcomes remains poorly understood. This systematic review and meta-analysis aimed to synthesise existing evidence on the influence of weight gain on patient and graft outcomes following kidney transplantation to enhance clinical practice and optimise post-transplant care strategies.

MATERIALS AND METHODS

A literature search was conducted across databases such as PubMed and Scopus for peer-reviewed studies published up to 8 August 2024. We included adult kidney transplant recipients (ages 18 years and older) with substantial and clinically relevant post-transplant weight gain and a control group without such changes, focusing on outcomes including all-cause mortality, graft survival, cardiovascular events and acute rejection.

RESULTS

The pooled analysis, which included data from 11 studies, indicated no significant association between post-transplant weight gain and the risk of all-cause mortality (hazard ratio [HR] 1.21, 95% confidence interval [CI] 0.69 to 2.10, p = 0.51; I2 = 28%), cardiovascular events (HR 0.93, 95% CI 0.43 to 2.01, p = 0.85; I2 = 32%) or acute rejection (HR 1.13, 95% CI 0.76 to 1.68, p = 0.55; I2 = 9%). However, weight gain was significantly associated with an increased risk of graft failure (HR 1.58, 95% CI 1.22 to 2.05, p < 0.001; I2 = 0%).

CONCLUSION

Substantial and clinically relevant weight gain after kidney transplant was associated with a higher risk of graft failure. Within the timeframes of study observation, risks of all-cause mortality, cardiovascular events or acute rejection were not increased by weight gain in kidney transplant recipients.

Components of Residential Neighborhood Deprivation and Their Impact on the Likelihood of Live-Donor and Preemptive Kidney Transplantation

INTRODUCTION

Adults residing in deprived neighborhoods face various socioeconomic stressors, hindering their likelihood of receiving live-donor kidney transplantation (LDKT) and preemptive kidney transplantation (KT). We quantified the association between residential neighborhood deprivation index (NDI) and the likelihood of LDKT/preemptive KT, testing for a differential impact by race and ethnicity.

METHODS

We studied 403 937 adults (age ≥ 18) KT candidates (national transplant registry; 2006-2021). NDI and its 10 components were averaged at the ZIP-code level. Cause-specific hazards models were used to quantify the adjusted hazard ratio (aHR) of LDKT and preemptive KT across tertiles of NDI and its 10 components.

RESULTS

Candidates residing in high-deprivation neighborhoods were more likely to be female (40.1% vs. 36.2%) and Black (41.9% vs. 17.7%), and were less likely to receive both LDKT (aHR = 0.66, 95% confidence interval [CI]: 0.64-0.67) and preemptive KT (aHR = 0.60, 95% CI: 0.59-0.62) than those in low-deprivation neighborhoods. These associations differedby race and ethnicity (Black: aHRLDKT = 0.58, 95% CI: 0.55-0.62; aHRpreemptive KT = 0.68, 95% CI: 0.63-0.73; Pinteractions: LDKT < 0.001; Preemptive KT = 0.002). All deprivation components were associated with the likelihood of both LDKT and preemptive KT (except median home value): for example, higher median household income (LDKT: aHR = 1.08, 95% CI: 1.07-1.09; Preemptive KT: aHR = 1.10, 95% CI: 1.08-1.11) and educational attainments (≥high school [LDKT: aHR = 1.17, 95% CI: 1.15-1.18; Preemptive KT: aHR = 1.23, 95% CI: 1.21-1.25]).

CONCLUSION

Residence in socioeconomically deprived neighborhoods is associated with a lower likelihood of LDKT and preemptive KT, differentially impacting minority candidates. Identifying and understanding which neighborhood-level socioeconomic status contributes to these racial disparities can be instrumental in tailoring interventions to achieve health equity in LDKT and preemptive KT.

COVID-19 and Access to Kidney Transplantation for Older Candidates in the United States: A National Registry Study

Rationale & Objective

Coronavirus disease (COVID)-19 has likely impacted accessibility to transplantation services among older adults (age ≥65 years). We quantified the impact of COVID-19 on kidney transplantation access for older kidney-only candidates registered on the United States (US) kidney waitlist.

Study Design

Retrospective analysis of registry data.

Setting & Participants

57,222 older adults who were part of or added to the US kidney waitlist between January 1, 2016 and February 28, 2022, identified using the Scientific Registry of Transplant Recipients (SRTR).

Exposures

Four COVID-19 waves and one nonwave period based on the national incidence of COVID-19 in the US (initial: March 15-May 30, 2020; winter 2020-2021: December 1, 2020-January 31, 2021; delta: August 1, 2021-September 30, 2021; omicron: December 1, 2021-February 28, 2022; nonwave: inter-wave periods).

Outcomes

Waitlist registrations, deceased-donor kidney transplants, living-donor kidney transplants, waitlist mortality, and waitlist removals due to deteriorating condition (hereafter referred to as removals).

Analytical Approach

Poisson regression for the adjusted incidence rate ratio (aIRR) of each outcome during the COVID-19 waves and the nonwave period relative to reference (January 1, 2016-December 31, 2019), adjusted for seasonality and secular trends.

Results

Waitlist registrations initially declined and increased henceforth. Deceased-donor kidney transplants and living-donor kidney transplants remained below-expected levels during all waves. Waitlist mortality peaked during the winter 2020-2021 wave (aIRR: 1.701.982.30) and has declined since; mortality rates were 139%, 107%, and 251% above expected for Black candidates, men, and candidates aged ≥75 years, respectively, during the winter 2020-2021 wave. Removals increased from 22% below expected levels (initial wave) to 26% above expected levels (omicron wave); removals were nonsignificantly higher than expected during the omicron wave for older Black and Hispanic candidates.

Limitations

The findings are not generalizable to those listed at earlier ages with prolonged waitlist times. Additionally, using national COVID-19 incidence does not consider local policy and health care variations. Lastly, aIRRs must be interpreted cautiously due to smaller daily event counts.

Conclusions

COVID-19 was associated with fewer transplants and increased mortality and removals in older kidney transplant candidates. Transplant providers should consider this impact and implement policies and practices to ensure the continuity of care.

Plain-Language Summary

The proportion of older adults on the kidney transplant waitlist is increasing, but the impact of COVID-19 on this population is not well characterized. In this study, we looked at incident waitlist registrations, deceased- and living-donor kidney transplants, and waitlist mortality and removals due to deteriorating condition over 4 waves of COVID-19. We found that transplantation services did not fully recover to prepandemic levels as of March 2022. Notably, racial/ethnic minorities and older men experienced lower rates of kidney transplants and higher rates of waitlist mortality, respectively, relative to White candidates and older women. Identifying vulnerable subpopulations affected by COVID-19 and its long-term impact is crucial for creating strategies to ensure the continuity of care in this population during public health emergencies.