Pregnancy-Induced Sensitization Promotes Sex Disparity in Living Donor Kidney Transplantation

Sex and gender as predictors for allograft and patient-relevant outcomes after kidney transplantation

BACKGROUND

Sex, as a biological construct, and gender, defined as the cultural attitudes and behaviours attributed by society, may be associated with allograft loss, death, cancer, and rejection. Other factors, such as recipient age and donor sex, may modify the association between sex/gender and post-transplant outcomes.

OBJECTIVES

We sought to evaluate the prognostic effects of recipient sex and, separately, gender as independent predictors of graft loss, death, cancer, and allograft rejection following kidney or simultaneous pancreas-kidney (SPK) transplantation. We aimed to evaluate this prognostic effect by defining the relationship between recipient sex or gender and post-transplantation outcomes identifying reasons for variations between sexes and genders, and then quantifying the magnitude of this relationship.

SEARCH METHODS

We searched MEDLINE and EMBASE databases from inception up to 12 April 2023, through contact with the Cochrane Kidney and Transplant Information Specialist, using search terms relevant to this review and no language restrictions.

SELECTION CRITERIA

Cohort, case-control, or cross-sectional studies were included if sex or gender were the primary exposure and clearly defined. Studies needed to focus on our defined outcomes post-transplantation. Sex was defined as the chromosomal, gonadal, and anatomical characteristics associated with the biological sex, and we used the terms "males" and "females". Gender was defined as the attitudes and behaviours that a given culture associates with a person's biological sex, and we used the terms "men" and "women".

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the references for eligibility, extracted the data and assessed the risk of bias using the Quality in Prognosis Studies (QUIPS) tool. Whenever appropriate, we performed random-effects meta-analyses to estimate the mean difference in outcomes. The outcomes of interest included the Standardised Outcomes in Nephrology-Kidney Transplant (SONG-Tx) core outcomes, allograft loss, death, cancer (overall incidence and site-specific) and acute or chronic graft rejection.

MAIN RESULTS

Fifty-three studies (2,144,613 patients; range 59 to 407,963) conducted between 1990 and 2023 were included. Sixteen studies were conducted in the Americas, 12 in Europe, 11 in the Western Pacific, four in the Eastern Mediterranean, three in Africa, two in Southeast Asia, and five across multiple regions. All but one study focused on sex rather than gender as the primary exposure of interest. The number identified as male was 54%; 49 studies included kidney transplant recipients, and four studies included SPK transplant recipients. Twenty-four studies included adults and children, 25 studies included only adults, and four studies included only children. Data from 33 studies were included in the meta-analyses. Among these, six studies presented unadjusted hazard ratios (HRs) that assessed the effect of recipient sex on kidney allograft loss. The other studies reported risk ratios (RRs) for the pre-defined outcomes. Notably, the decision to restrict the meta-analyses to unadjusted estimates arose from the variation in covariate adjustment methods across studies, lacking a common set of adjusted variables. Only three studies considered the modifying effect of recipient age on graft loss or death, which is likely crucial to evaluating sex differences in post-transplant outcomes. No studies considered the modifying effect of recipient age on cancer incidence or allograft rejection risk. In low certainty evidence, compared with male recipients, being female may make little or no difference in kidney allograft loss post-transplantation (7 studies, 5843 patients: RR 0.91, 95% CI 0.73 to 1.12; I2 = 73%). This was also observed in studies that included time-to-event analyses (6 studies, 238,937 patients; HR 1.07, 95% CI, 0.95 to 1.20; I2 = 44%). Two recent large registry-based cohort studies that considered the modifying effects of donor sex and recipient age showed that female recipients under 45 years of age had significantly higher graft loss rates than age-matched male recipients in the setting of a male donor. In contrast, female recipients 60 years and older had lower graft loss rates than age-matched male recipients, regardless of donor sex. Compared with male recipients, being female may make little or no difference in death up to 30 years post-transplantation; however, the evidence is very uncertain (13 studies, 60,818 patients: RR 0.94, 95% CI 0.81 to 1.09; I2 = 92%). Studies that considered the modifying effect of recipient age and donor sex showed that female recipients had a higher excess death risk than males under 45 years of age in the setting of a male donor. Compared with male recipients, being female may make little or no difference in cancer incidence up to 20 years post-transplantation; however, the evidence is very uncertain (7 studies, 25,076 patients; RR 0.84, 95% CI 0.70 to 1.01; I2 = 60%). Compared with male recipients, being female may make little or no difference in the incidence of acute and chronic kidney allograft rejection up to 15 years post-transplantation (9 studies, 6158 patients: RR 0.89, 95% CI 0.75 to 1.05; I2 =54%; low certainty evidence). One study assessed gender and reported that when compared with men, women experienced better five-year survival in high (HR 0.71, 95% CI 0.59 to 0.87) and middle-income areas (HR 0.82, 95% CI 0.74 to 0.92), with no difference in low-income areas (HR 0.85, 95% CI 0.72 to 1.01). There was considerable uncertainty regarding any association between sex or gender and post-transplant patient-relevant outcomes. This was primarily due to clinical and methodological heterogeneity. The observed clinical heterogeneity between studies could be attributed to diverse patient characteristics within sample populations. As a result of limited sex-stratified demographic data being provided, further investigation of this heterogeneity was constrained. However, factors contributing to this finding may include recipient age, donor age, types, and sex. Methodological heterogeneity was noted with the interchangeable use of sex and gender, outcome misclassification, the use of different measures of effects, inconsistent covariate profiles, and disregard for important effect modification.

AUTHORS' CONCLUSIONS

There is very low to low certainty evidence to suggest there are no differences in kidney and pancreas allograft survival, patient survival, cancer, and acute and chronic allograft rejection between male and female kidney and SPK transplant recipients.

Lower access to kidney transplantation for women in France is not explained by comorbidities and social deprivation

BACKGROUND

Access to kidney transplantation (KT) remains challenging for patients with end-stage kidney disease. This study assessed women's access to KT in France by considering comorbidities and neighbourhood social deprivation.

METHODS

All incident patients 18-85 years old starting dialysis in France between 1 January 2017 and 31 December 2019 were included. Three outcomes were assessed: access to the KT waiting list after dialysis start, KT access after waitlisting and KT access after dialysis start. Cox and Fine-Gray models were used. Gender-European Deprivation Index and gender-age interactions were tested and analyses were performed among strata if required.

RESULTS

A total of 29 395 patients were included (35% of women). After adjusting for social deprivation and comorbidities, women were less likely to be waitlisted at 1 year {adjusted hazard ratio [adjHR] 0.91 [95% confidence interval (CI) 0.87-0.96]} and 3 years [adjHR 0.87 (95% CI 0.84-0.91)] after dialysis initiation. This disparity concerned mainly women ≥60 years of age [adjHR 0.76 (95% CI 0.71-0.82) at 1 year and 0.75 (0.71-0.81) at 3 years]. Access to KT after 2 years of waitlisting was similar between genders. Access to KT was similar between genders at 3 years after dialysis start but decreased for women after 4 years [adjHR 0.93 (95% CI 0.88-0.99)] and longer [adjHR 0.90 (95% CI 0.85-0.96)] follow-up.

CONCLUSIONS

In France, women are less likely to be waitlisted and undergo KT. This is driven by the ≥60-year-old group and is not explained by comorbidities or social deprivation level.

Sex/Gender Disparities in Preemptive Referrals for Kidney Transplantation

Introduction

Sex/gender inequities persist in access to kidney transplantation. Whether differences in preemptive referral (i.e., referral before dialysis start) explain this inequity remains unknown.

Methods

All adults (aged 18-79 years; N = 44,204) initiating kidney replacement therapy (KRT; dialysis or transplant) in Georgia (GA), North Carolina (NC), or South Carolina (SC) between 2015 and 2019 were identified from the United States Renal Data System (USRDS). Individuals were linked to the Early Steps to Kidney Transplant Access Registry (E-STAR) to obtain data on preemptive referral and followed-up with through November 13, 2020, for outcomes of waitlisting and living donor transplant. Logistic regression assessed the association between sex/gender and likelihood of preemptive referral among all KRT patients. Cox-proportional hazards assessed the association between sex/gender and waitlisting or living donor among preemptively referred patients.

Results

Overall, men and women were similarly likely to be preemptively referred (odds ratio [OR]: 0.99 [0.95-1.04]). Preemptively referred women (vs. men) were, on average, younger and with fewer comorbidities. There were no sex/gender differences in waitlisting once patients were preemptively referred (hazard ratio [HR]: 0.97 [0.91-1.03]); however, women (vs. men) who were preemptively referred remained 25% (HR: 0.75 [0.66-0.86]) less likely to receive a living donor transplant.

Conclusion

In the Southeast US, men and women initiating KRT are similarly likely to be preemptively referred for a kidney transplant, and this appears, at least in part, to mitigate known sex/gender inequities in access to waitlisting, but not living donor transplant. Despite this, preemptively referred women, on average, had a more favorable medical profile relative to preemptively referred men.

Exploring Potential Gender-Based Disparities in Referral for Transplant, Activation on the Waitlist and Kidney Transplantation in a Canadian Cohort

Introduction

In the United States, women are less likely to be referred, activated on the waitlist, or undergo kidney transplant (KT) than men; contemporary Canadian data regarding access to transplant for women are lacking.

Methods

Among patients initiating dialysis in Nova Scotia (NS), Canada from 2010 to 2020, we examined the association of candidate gender with overall access to KT, including the following: (i) odds of transplant referral within 1 year of dialysis initiation, (ii) odds of activation on the transplant waitlist (if referred), and (iii) time-to-transplantation (if activated) using logistic regression or Cox proportional hazards models as appropriate.

Results

Among 749 patients deemed potentially eligible for transplant, women had lower transplant rates than men (adjusted hazard ratio [aHR]: 0.53, 95% confidence interval [CI]: 0.36-0.78); this was amplified among patients aged >60 years (aHR: 0.25, 95% CI: 0.09-0.69). Compared with men, women had a lower adjusted odds of transplant referral (adjusted odds ratio [aOR]: 0.57, 95% CI: 0.35-0.93) by 1 year after dialysis initiation. Among those referred, women had lower odds of waitlist activation than men (aOR: 0.58, 95% CI: 0.30-1.11); and among those activated, women had lower hazard of KT (aHR: 0.74, 95% CI: 0.51-1.09), though these differences were not statistically significant. Women in NS experience lower overall access to transplant, including less referral, activation and KT compared with men.

Conclusion

Gender-based barriers to any of (or in this case each of) referral, activation, or transplantation result in inequities in access; identification of disparities at these critical decision points is an important first step toward ensuring equal access for all.

A systematic review of psychosocial and sex-based contributors to gender disparities in the United States across the steps towards kidney transplantation

INTRODUCTION

Persistent findings suggest women and patients identified as "female" are less likely to receive a kidney transplant. Furthermore, the limited research on transplantation among transgender and gender diverse people suggests this population is susceptible to many of the same psychosocial and systemic barriers.

OBJECTIVE

This review sought to 1) highlight terminology used to elucidate gender disparities, 2) identify barriers present along the steps to transplantation, and 3) summarize contributors to gender disparities across the steps to transplantation.

METHODS

A systematic review of gender and sex disparities in the steps towards kidney transplantation was conducted in accordance with PRISMA guidelines across four social science and public health databases from 2005 to 23.

RESULTS

The search yielded 1696 initial results, 33 of which met inclusion criteria. A majority of studies followed a retrospective cohort design (n = 22, 66.7%), inconsistently used gender and sex related terminology (n = 21, 63.6%), and reported significant findings for gender and sex disparities within the steps towards transplantation (n = 28, 84.8%). Gender disparities among the earlier steps were characterized by patient-provider communication and perception of medical suitability whereas disparities in the later steps were characterized by differential outcomes based on older age, an above average BMI, and Black racial identity. Findings for transgender patients pointed to issues computing eGFR and the need for culturally tailored care.

DISCUSSION

Providers should be encouraged to critically examine the diagnostic criteria used to determine transplant eligibility and adopt practices that can be culturally tailored to meet the needs of patients.

Calibration of Priority Points for Sensitization Status of Kidney Transplant Candidates in the United States

Key Points

There are multiple factors associated with high sensitization levels among kidney transplant candidates, which differ by candidate sex. Since the initiation of the kidney allocation system, candidates with higher sensitization have higher rates of deceased donor transplantation. Priority points assigned to candidates associated with sensitization have led to inequities in access to deceased donor transplantation.

Background

A primary change to the national organ allocation system in 2014 for deceased donor kidney offers was to weight candidate priority on the basis of sensitization (i.e ., calculated panel reactive antibody percentage [cPRA%]) using a sliding scale. Increased priority for sensitized patients could improve equity in access to transplantation for disadvantaged candidates. We sought to evaluate the effect of these weights using a contemporary cohort of adult US kidney transplant candidates.

Methods

We used the national Scientific Registry of Transplant Recipients to evaluate factors associated with sensitization using multivariable logistic models and rates of deceased donor transplantation using cumulative incidence models accounting for competing risks and multivariable Cox models.

Results

We examined 270,912 adult candidates placed on the waiting list between January 2016 and September 2023. Six-year cumulative incidence of deceased donor transplantation for candidates with cPRA%=80–85 and 90–95 was 48% and 53%, respectively, as compared with 37% for candidates with cPRA%=0–20. In multivariable models, candidates with high cPRA% had the highest adjusted hazards for deceased donor transplantation. There was significant effect modification such that the association of high cPRA% with adjusted rates of deceased donor transplantation varied by region of the country, sex, race and ethnicity, prior dialysis time, and blood type.

Conclusions

The results indicate that the weighting algorithm for highly sensitized candidates may overinflate the need for prioritization and lead to higher rates of transplantation. Findings suggest recalibration of priority weights for allocation is needed to facilitate overall equity in access to transplantation for prospective kidney transplant candidates. However, priority points should also account for subgroups of candidates who are disadvantaged for access to donor offers.

Expanding the access to kidney transplantation: Strategies for kidney transplant programs

Kidney transplantation is the most successful kidney replacement therapy available, resulting in improved recipient survival and societal cost savings. Yet, nearly 70 years after the first successful kidney transplant, there are still numerous barriers and untapped opportunities that constrain the access to transplant. The literature describing these barriers is extensive, but the practices and processes to solve them are less clear. Solutions must be multidisciplinary and be the product of strong partnerships among patients, their networks, health care providers, and transplant programs. Transparency in the referral, evaluation, and listing process as well as organ selection are paramount to build such partnerships. Providing early culturally congruent and patient-centered education as well as maximizing the use of local resources to facilitate the transplant work up should be prioritized. Every opportunity to facilitate pre-emptive kidney transplantation and living donation must be taken. Promoting the use of telemedicine and kidney paired donation as standards of care can positively impact the work up completion and maximize the chances of a living donor kidney transplant.

Gender and kidney transplantation

Kidney transplantation provides the best form of kidney replacement therapy with improvement in quality of life and longevity. However, disparity exists in its availability, utilisation and outcomes, not only due to donor availability or financial constraints but also arising from the influence of biological sex and its sociocultural attribute i.e., Gender. Women make up the majority of kidney donors but are less likely to be counselled regarding transpantation, be waitlisted or receive living/deceased donor kidney. Biological differences also contribute to differences in kidney transplantation among the sexes. Women are more likely to be sensitised owing to pregnancy, especially in multiparous individuals, complicating donor compatibility. A heightened immune system in women, evidenced by more autoimmune illnesses, increases the risk of allograft rejection and loss. Differences in the pharmacokinetics of transplant drugs owing to biological variances could also contribute to variability in outcomes. Transgender medicine is also increasingly becoming a relevant topic of study, providing greater challenges in the form of hormonal manipulations and anatomic changes. It is thus important to determine and study transplantation and its nuances in this backdrop to be able to provide relevant sex and gender-specific interventions and design better practices for optimum kidney transplant utilisation and outcomes.

Relationships, race/ethnicity, gender, age, and living kidney donation evaluation willingness

Racial/ethnic and gender disparities in living donor kidney transplantation are large and persistent but incompletely explained. One previously unexplored potential contributor to these disparities is differential willingness to donate to recipients in specific relationships such as children, parents, and friends. We collected and analyzed data from an online sample featuring an experimental vignette in which respondents were asked to rate their willingness to donate to a randomly chosen member of their family or social network. Results show very large differences in respondents' willingness to donate to recipients with different relationships to them, favoring children, spouses/partners, siblings, and parents, and disfavoring friends, aunts/uncles, and coworkers. Evidence suggesting an interactive effect between relationship, respondent race/ethnicity, respondent or recipient gender, was limited to a few cases. At the p < 0.05 level, the parent-recipient gender interaction was statistically significant, favoring mothers over fathers, as was other/multiracial respondents' greater willingness to donate to friends compared to Whites. Additionally, other interactions were significant at the p < 0.10 level, such as Hispanics' and women's higher willingness to donate to parents compared to Whites and men respectively, women's lower willingness to donate to friends compared to men, and Blacks' greater willingness to donate to coworkers than Whites. We also examined differences by age and found that older respondents were less willing to donate to recipients other than their parents. Together these results suggest that differential willingness to donate by relationship group may be a moderately important factor in understanding racial/ethnic and gender disparities in living donor kidney transplantation.

Gender disparities in kidney replacement therapies and transplantation in Colombia

BACKGROUND

In chronic kidney disease (CKD), there are historical inequities in multiple stages of the pathway for organ transplantation. Women have been recognized as disadvantaged within this process even after several efforts. Therefore, we aimed to analyze the prevalence and incidence of CKD by gender and their access to Kidney replacement therapy (KRT) in Colombia.

METHODS

A cross-sectional study based on secondary analysis of national information on CKD, hypertension, diabetes, waiting list, deceased, and living donor transplantation between 2015 and 2020.

RESULTS

In Colombia, 4.934.914 patients were diagnosed with hypertension, diabetes, or CKD. 60,64% were female, with a mean age of 63.84 years (SD 14,36). Crude incidence for hypertension (10.85 vs. 7.21 /1000 inhabitants), diabetes mellitus (3.77 vs. 2.98 /1000 inhabitants), and CKD (4 vs. 2 /1000 inhabitants) was higher for females. Crude incidence for KRT was 86.45 cases /100.0000 inhabitants. In 2020, 2978 patients were on the waiting list, 44% female. There were 251 deaths on the waiting list, 38% female. This year, 517 kidney transplants were performed, and only 40% were female.

CONCLUSION

In Colombia, there are proportionally more females with CKD and precursor comorbidities. Nevertheless, there are fewer females on the waiting list and transplanted annually.

Intersectional race and gender disparities in kidney transplant access in the United States: a scoping review

BACKGROUND

Gender and racial disparities in kidney transplant access are well established, however how gender and race interact to shape access to kidney transplant is less clear. Therefore, we examined existing literature to assess what is known about the potential interaction of gender and race and the impact on access to kidney transplantation in the US.

METHODS

Following PRISMA guidelines, we conducted a scoping review and included quantitative and qualitative studies published in English between 1990 and May 31, 2023 among adult end-stage kidney disease patients in the US. All studies reported on access to specific transplant steps or perceived barriers to transplant access in gender and race subgroups, and the intersection between the two. We narratively synthesized findings across studies.

RESULTS

Fourteen studies met inclusion criteria and included outcomes of referral (n = 4, 29%), evaluation (n = 2, 14%), waitlisting (n = 4, 29%), transplantation (n = 5, 36%), provider perceptions of patient transplant candidacy (n = 3, 21%), and patient preferences and requests for a living donor (n = 5, 36%). Overall, we found that White men have the greatest access at all steps of the transplant process, from referral to eventual living or deceased donor transplantation. In contrast, women from racial or ethnic minorities tend to have the lowest access to kidney transplant, in particular living donor transplant, though this was not consistent across all studies.

CONCLUSIONS

Examining how racism and sexism interact to shape kidney transplant access should be investigated in future research, in order to ultimately shape policies and interventions to improve equity.

Sociodemographic Disparities in Adults with Kidney Failure: A Meta-Analysis

This meta-analysis aims to assess current evidence regarding sociodemographic disparities among adults with kidney failure. Medline, Scopus, Web of Science, CENTRAL, and Google Scholar were systematically searched from inception to 20 February 2022. Overall, 165 cohort studies were included. Compared to White patients, dialysis survival was significantly better among Black (hazard ratio-HR: 0.68; 95% CI: 0.61-0.75), Asian (HR: 0.67; 95% CI: 0.61-0.72) and Hispanic patients (HR: 0.80; 95% CI: 0.73-0.88). Black individuals were associated with lower rates of successful arteriovenous fistula use, peritoneal dialysis and kidney transplantation, as well as with worse graft survival. Overall survival was significantly better in females after kidney transplantation compared to males (HR: 0.87; 95% CI: 0.84-0.90). Female sex was linked to higher rates of central venous catheter use and a lower probability of kidney transplantation. Indices of low SES were associated with higher mortality risk (HR: 1.22, 95% CI: 1.14-1.31), reduced rates of dialysis with an arteriovenous fistula, peritoneal dialysis and kidney transplantation, as well as higher graft failure risk. In conclusion, Black, Asian and Hispanic patients present better survival in dialysis, while Black, female and socially deprived patients demonstrate lower rates of successful arteriovenous fistula use and limited access to kidney transplantation. PROSPERO registration: CRD42022300839.

Mechanisms and consequences of sex differences in immune responses

Biological sex differences refer to differences between males and females caused by the sex chromosome complement (that is, XY or XX), reproductive tissues (that is, the presence of testes or ovaries), and concentrations of sex steroids (that is, testosterone or oestrogens and progesterone). Although these sex differences are binary for most human individuals and mice, transgender individuals receiving hormone therapy, individuals with genetic syndromes (for example, Klinefelter and Turner syndromes) and people with disorders of sexual development reflect the diversity in sex-based biology. The broad distribution of sex steroid hormone receptors across diverse cell types and the differential expression of X-linked and autosomal genes means that sex is a biological variable that can affect the function of all physiological systems, including the immune system. Sex differences in immune cell function and immune responses to foreign and self antigens affect the development and outcome of diverse diseases and immune responses.

Are Differences in Living Kidney Donation Rates a Sex or a Gender Disparity?

Sex-disaggregated data reveal significant disparities in living kidney donation, with more female than male living kidney donors in most countries and proportions over 60% in some countries. We summarize the present state of knowledge with respect to the potential drivers of this disparity and argue that it is primarily driven by gender-related factors. First, we present the differences between sex and gender and then proceed to summarize the potential medical reasons that have been proposed to explain why males are less likely to be living kidney donors than females, such as the higher prevalence of kidney failure in males. We then present counterarguments as to why biological sex differences are not enough to explain lower living kidney donation among males, such as a higher prevalence of chronic kidney disease among females, which could affect donation rates. We argue that gender differences likely provide a better explanation as to why there are more women than men living kidney donors and explore the role of economic and social factors, as well as gender roles and expectations, in affecting living kidney donation among both men and women. We conclude with the need for a gender analysis to explain this complex psychosocial phenomenon in living kidney donation.

Act Together and Act Now to Overcome Gender Disparity in Organ Transplantation

Gender disparity refers to the unequal treatment or a perception of individuals based on their gender and arises from differences in socially constructed gender roles. In the field of transplantation, gender inequality arises at different stages, affecting access to medical care, donation practices, and posttransplant followup care. Gender disparity in transplantation is not limited to any geographic region but is thought to be more prevalent in developing nations. An unusually high number of female donations with relatively fewer female recipients is not only attributable to the low economy but a congregation of medical, social, cultural, and psychological factors. Gender disparities can also be shown in transplant-related professional societies. This review highlights the complexities of spousal donation and vulnerability of women, especially in the developing world. There is a growing need to further modify transplant policies to tackle gender disparities, especially in living related donation. Systematic research in the context of gender-related concerns in transplantation will further aid in understanding the complexities and formulating policies for eliminating gender disparities. Gender disparity is a global problem and not merely limited to transplantation.

Temporal trends in kidney paired donation in the United States: 2006-2021 UNOS/OPTN database analysis

Kidney paired donation (KPD) is a major innovation that is changing the landscape of kidney transplantation in the United States. We used the 2006-2021 United Network for Organ Sharing data to examine trends over time. KPD is increasing, with 1 in 5 living donor kidney transplants (LDKTs) in 2021 facilitated by KPD. The proportion of LDKT performed via KPD was comparable for non-Whites and Whites. An increasing proportion of KPD transplants are going to non-Whites. End-chain recipients are not identified in the database. To what extent these trends reflect how end-chain kidneys are allocated, as opposed to increase in living donation among minorities, remains unclear. Half the LDKT in 2021 in sensitized (panel reactive antibody ≥ 80%) and highly sensitized (panel reactive antibody ≥ 98%) groups occurred via KPD. Yet, the proportion of KPD transplants performed in sensitized recipients has declined since 2013, likely due to changes in the deceased donor allocation policies and newer KPD strategies such as compatible KPD. In 2021, 40% of the programs reported not performing any KPD transplants. Our study highlights the need for understanding barriers to pursuing and expanding KPD at the center level and the need for more detailed and accurate data collection at the national level.

Association between calculated panel reactive antibody and waitlist outcomes in the 2018 heart allocation system

BACKGROUND

The impact of heart transplant (HT) waitlist candidate sensitization on waitlist outcomes in the US is unknown.

METHODS

Adult waitlist outcomes in OPTN (October 2018-September 2022) by calculated panel reactive antibody (cPRA) were modeled to identify thresholds of clinical significance. The primary outcome was the rate of HT by cPRA category (low: 0-35, middle: >35-90, high: >90) assessed using multivariable competing risk analysis (compete: waitlist removal for death or clinical deterioration). The secondary outcome was waitlist removal for death or clinical deterioration.

RESULTS

The elevated cPRA categories were associated with lower rates of HT. Candidates in the middle (35-90) and high cPRA categories (>90) had an adjusted 24% lower rate (hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.80-0.92) and 61% lower rate (HR 0.39 95% CI. 0.33-0.47) of HT than the lowest category, respectively. Waitlist candidates in the high cPRA category listed in the top acuity strata (Statuses 1, 2) had increased rates of delisting for death or deterioration compared to those in the low cPRA category (adjusted HR 2.9, 95% CI 1.5-5.5), however, elevated cPRA (middle, high) was not associated with an increased rate of death and delisting when the cohort was considered as a whole.

CONCLUSIONS

Elevated cPRA was associated with reduced rates of HT across all waitlist acuity tiers. Among HT waitlist candidates listed at the top acuity strata, the high cPRA category was associated with increased rates of delisting due to death or deterioration. Elevated cPRA may require consideration for critically ill candidates under continuous allocation.

Perspectives of Nephrologists on Gender Disparities in Access to Kidney Transplantation

BACKGROUND

Gender disparities in access to kidney transplantation are apparent, with women being up to 20% less likely to receive kidney transplant compared with men across different settings and socioeconomic backgrounds. We aimed to describe nephrologists' perspectives on gender disparities in access to kidney transplantation.

METHODS

Fifty-one nephrologists (55% women) from 22 countries participated in semistructured interviews from October 2019 to April 2020. We analyzed the transcripts thematically.

RESULTS

We identified three themes: caregiving as a core role (coordinators of care for partners, fulfilling family duties over own health, maternal protectiveness, and inherent willingness and generosity), stereotyping and stigma (authority held by men in decision making, protecting the breadwinner, preserving body image and appearance, and safeguard fertility), social disadvantage and vulnerability (limited information and awareness, coping alone and lack of support, disempowered by language barriers, lack of financial resources, and without access to transport).

CONCLUSIONS

Gender disparities in access to kidney transplantation are perceived by nephrologists to be exacerbated by gender norms and values, stigma and prejudice, and educational and financial disadvantages that are largely encountered by women compared with men across different socioeconomic settings.

Sex and Gender Disparities in Living Kidney Donation: A Scoping Review

Background

Women are more likely than men to be living kidney donors. We summarized the evidence concerning the reasons behind sex and gender disparities in living kidney donation (LKD).

Methods

A scoping review of quantitative and qualitative evidence on reasons for sex and gender disparities in LKD was conducted from inception to March 2023.

Results

Of 1123 studies screened, 45 were eligible for inclusion. Most studies were from North America, Europe, and Central Asia (n = 33, 73%). A predominance of women as living donors (55%-65%) was observed in 15 out of 18 (83%) studies. Reasons for sex and gender disparities in LKD included socioeconomic, biological, and cognitive or emotional factors. A gendered division of roles within the families was observed in most studies, with men being the primary income earner and women being the main caregiver. Fear of loss of income was a barrier to male donation. Human leukocyte antigen sensitization through pregnancy in female recipients precluded male partner donation, whereas female donation was supported by altruism and a positive attitude toward LKD.

Conclusions

Sex imbalance in LKD is prevalent, with a predominance of women as living donors. Such disparities are driven by societal and cultural perceptions of gender roles, pregnancy-induced sensitization, and attitudes toward donation and at least some of these factors are modifiable. Donor compensation to support predonation assessments and income loss, implementation of innovative desensitization treatments, promotion of paired kidney exchange program, and targeted educational initiatives to promote equitable living donation may help to close the gender gap in LKD.

Sociodemographic Drivers of Donor and Recipient Gender Disparities in Living Kidney Donation in Australia

Background

Females account for 60% of all living kidney donors worldwide. We defined the proportion of female to male donors for living donor kidney transplantation stratified by recipient gender, and explored the factors associated with female kidney donation.

Methods

Data from the ANZDATA (Australian and New Zealand Dialysis and Transplantation) and ANZOD (Australian and New Zealand Organ Donor) registries (2002-2019) were used to identify the sociodemographic characteristics and their interactions associated with living donation from female donors. We derived the predicted probabilities from adjusted logistic models using marginal means.

Results

Of 3523 living donor pairs, 2203 (63%) recipients were male, and 2012 (57%) donors were female. Male recipients were more likely to receive kidneys from female donors than male donors. Donor and recipient sex association was modified by donor-recipient relationship (P < 0.01), with sensitivity analysis suggesting that spousal donor-recipient pairs drive this interaction. Older recipients residing in regional or remote areas were more likely to receive kidneys from female donors compared with those from major cities (aged ≥60 years: 0.67 [0.63-0.71] vs. aged <60 years: 0.57 [0.53-0.60]).

Conclusions

Factors associated with female donation include recipient sex, with spousal donors contributing to the interaction between recipient gender and donor-recipient relationship. Recipient age and location of residence have interactive effects on the likelihood of living donor transplantation from female donors.

The ties that transplant: The social capital determinants of the living kidney donor relationship distribution

The network perspective on social capital decomposes it into ego's network size, alters' relevant resources, and social factors moderating access to alters' resources, but rarely examines how it is distributed across relationship types. Using this approach, I investigate the situationally-relevant social capital relationship distribution and its association with health-related social support, with an application to the living kidney donor relationship distribution. Analyzing an original survey of transplant candidates (N = 72) and their reports on their family and friends (N = 1548), I compare the tie count, donation-relevant biomedical resource, and tie strength relationship distributions to administrative data on the national distribution of living kidney donor relationships. I find that the tie strength relationship distribution matches the completed living kidney donor relationship distribution far better than the tie count and donation-relevant biomedical resource relationship distributions. These conclusions are upheld in race- and gender-stratified analyses and are robust across alternative approaches.

Alert! Does Prolonged Temporary Support Induce an Immunological Response?

Little is known about the development of human leukocyte antigen antibodies with use of the temporary transvalvular pump 5.5 mechanical circulatory support device. This case reports a patient who developed de novo antibodies prior to his heart transplantation and remains free of any episodes of rejection post transplantation to date. (Level of Difficulty: Advanced.).

Desensitization and belatacept-based maintenance therapy in pregnancy-sensitized monkeys receiving a kidney transplant

Among sensitized patients awaiting a transplant, females are disproportionately represented, partly because of pregnancy-induced sensitization. Using female NHPs sensitized by pregnancy alone, we examined the efficacy of costimulation blockade and proteasome inhibition for desensitization. Three animals received no desensitization (control), and seven animals received weekly carfilzomib (27 mg/m2) and belatacept (20 mg/kg) before kidney transplantation. All animals received renal allografts from crossmatch-positive/maximally MHC-mismatched donors. Controls and three desensitized animals received tacrolimus-based immunosuppression. Four desensitized animals received additional belatacept with tacrolimus-based immunosuppression. Multiparous females had less circulating donor-specific antibody when compared to skin-sensitized males before transplantation. While females receiving desensitization showed only a marginal survival benefit over control females (MST = 11 days versus 63 days), additional belatacept to posttransplant maintenance significantly prolonged graft survival (MST > 164 days) and suppressed posttransplant DSA and circulating follicular helper T-like cells. This combination of therapies demonstrates great potential to reduce antibody-mediated rejection in sensitized recipients.

Representation of Women in Contemporary Kidney Transplant Trials

Women are often underrepresented in clinical trials. It is unclear if this applies to trials in kidney transplant (KT) and whether the intervention or trial focus influences this. In this study, the weighted participation-to-prevalence ratio (PPR) for women enrollees in KT trials was determined for leading medical transplant or kidney journals between 2018 and 2023 using meta-regression overall and in three sensitivity analyses by: 1) Whether the intervention involved immunosuppression; 2) Area of trial focus; rejection, cardiometabolic, infection, lifestyle, surgical; 3) Whether the intervention was medical/surgical or social/behavioral. Overall, 33.7% of participants in 24 trials were women. The overall pooled PPR for the included trials was 0.80, 95% CI 0.76-0.85, with significant heterogeneity between trials (I 2 56.6%, p-value < 0.001). Women had a lower PPR when the trial involved immunosuppression (PPR 0.77, 95% CI 0.72-0.82) than when it did not (PPR 0.86, 95% CI 0.80-0.94) and were less likely to participate in trials with a medical/surgical versus behavioral intervention; the lowest PPR for women was in studies examining rejection risk (PPR 0.75, 95% CI 0.70-0.81). There is better representation of women in KT trials compared to other medical disciplines, however women remain underrepresented in transplant trials examining immunosuppression and rejection.

P32: a sex- and gender-sensitive model for evidence-based precision medicine: from knowledge generation to implementation in the field of kidney transplantation

Precision medicine emerged as a promising approach to identify suitable interventions for individual patients with a particular health concern and at various time points. Technology can enable the acquisition of increasing volumes of clinical and "omics" data at the individual and population levels and support advanced clinical decision making. However, to keep pace with evolving societal realities and developments, it is important to systematically include sex- and gender-specific considerations in the research process, from the acquisition of knowledge to implementation. Building on the foundations of evidence-based medicine and existing precision medicine frameworks, we propose a novel evidence-based precision medicine framework in the form of the P3²model, which considers individual sex-related (predictive [P1], preventive [P2], and personalized [P3] medicine) and gender-related (participatory [P4], psychosocial [P5], and percipient [P6] medicine) domains and their intersection with ethnicity, geography, and other demographic and social variables, in addition to population, community, and public dimensions (population-informed [P7], partnered with community [P8], and public-engaging [P9] medicine, respectively). Through its ability to contextualize and reflect on societal realities and developments, our model is expected to promote consideration of diversity, equity, and inclusion principles and, thus, enrich science, increase reproducibility of research, and ensure its social impact.

Factors associated with health inequities in access to kidney transplantation in the USA: A scoping review

BACKGROUND

The kidney is the most needed organ for transplantation in the United States. However, demand and scarcity of this organ has caused significant inequities for historically marginalized groups. In this review, we report on the frequency of inequities in all steps of kidney transplantation from 2016 to 2022. Search criteria was based on the National Institute of Health's (NIH) 2022 list of populations who experience health inequities, which includes: race and ethnicity; sex or gender; Lesbian, Gay, Bisexual, Transgender, Queer + (LGBTQ+); underserved rural communities; education level; income; and occupation status. We outline steps for future research aimed at assessing interventions and programs to improve health outcomes.

METHODS

This scoping review was developed following guidelines from the Joanna Briggs Institute and PRISMA extension for scoping reviews. In July 2022, we searched Medline (via PubMed) and Ovid Embase databases to identify articles addressing inequities in access to kidney transplantation in the United States. Articles had to address at least one of the NIH's 2022 health inequity groups.

RESULTS

Our sample of 44 studies indicate that Black race, female sex or gender, and low socioeconomic status are negatively associated with referral, evaluation, and waitlisting for kidney transplantation. Furthermore, only two studies from our sample investigated LGBTQ+ identity since the NIH's addition of SGM in 2016 regarding access to transplantation. Lastly, we found no detectable trend in studies for the four most investigated inequity groups between 2016 and 2022.

CONCLUSION

Investigations in inequities for access to kidney transplantation for the two most studied groups, race/ethnicity and sex or gender, have shown no change in frequencies. Regarding race and ethnicity, continued interventions focused on educating Black patients and staff of dialysis facilities may increase transplant rates. Studies aimed at assessing effectiveness of the Kidney Paired Donation program are highly warranted due to incompatibility problems in female patients. The sparse representation for the LGBTQ+ population may be due to a lack of standardized data collection for sexual orientation. We recommend this community be engaged via surveys and further investigations.

Real-world data on renal transplantations from a tertiary-care hospital in North India, in context of Indian regulatory act-transplantation of human organs and tissues act (THOTA): A retrospective analysis

INTRODUCTION

Renal transplantation is the treatment of choice for patients suffering from end stage renal disease (ESRD). Indian regulations defined under Transplantation of Human Organs and Tissues Act (THOTA), 2014 restricts organ donations to near-related living donors to curb any malpractices like 'paid donors' in living-donor kidney transplantation (LDKT). The aim of our study was to look at real-world data of donor-recipient pairs and to identify relationship of donors (with their respective patients) and the common (or uncommon) DNA profiling methods used for supporting "claimed relationship" in accordance with the regulations.

MATERIAL AND METHODS

The donors were categorized and grouped into near-related donor, donors other than near-related donors, swap donors and deceased donors. Claimed relationship was confirmed, commonly by HLA typing, using SSOP method. In few cases, which were uncommon (and infrequent), autosomal DNA analysis, mitochondrial DNA analysis and Y-STR DNA analysis were performed to support the claimed relationship. Data collected included age, gender, relationship, DNA profiling test method.

RESULTS

Among the 514 donor-recipient pairs evaluated, numbers of female donors out-numbered male donors. The decreasing order of relationships in near-related donor group were wife>mother>father>sister>son>brother>husband> daughter>grandmother. 11.9% of donors were in the category of donors other than near-related donors. In 97.86% cases, the claimed relationship was supported by HLA typing and in just 2.1% cases autosomal DNA analysis>mitochondrial DNA analysis> Y-STR DNA analysis, in this order, were performed to establish relationship.

CONCLUSION

This study brought out gender disparity with women out-numbering men as donors. Among recipients, access to renal transplant was largely restricted to men. As far as relationship of donors to recipients was concerned, mostly near-related family members, like wife, were donors and claimed relationship was almost always (99%) was corroborated by HLA typing.

Addressing sex-based disparities in solid organ transplantation in the United States - a conference report

Solid organ transplantation provides the best treatment for end-stage organ failure, but significant sex-based disparities in transplant access exist. On June 25, 2021, a virtual multidisciplinary conference was convened to address sex-based disparities in transplantation. Common themes contributing to sex-based disparities were noted across kidney, liver, heart, and lung transplantation, specifically the existence of barriers to referral and wait listing for women, the pitfalls of using serum creatinine, the issue of donor/recipient size mismatch, approaches to frailty and a higher prevalence of allosensitization among women. In addition, actionable solutions to improve access to transplantation were identified, including alterations to the current allocation system, surgical interventions on donor organs, and the incorporation of objective frailty metrics into the evaluation process. Key knowledge gaps and high-priority areas for future investigation were also discussed.

Counselling, Research Gaps, and Ethical Considerations Surrounding Pregnancy in Solid Organ Transplant Recipients

Survival after solid-organ transplantation has improved significantly, and many contemporary transplant recipients are of childbearing potential. There are limited data to guide decision-making surrounding pregnancy after transplantation, variations in clinical practice, and significant knowledge gaps, all of which raise significant ethical issues. Post-transplant pregnancy is associated with an increased risk of maternal and fetal complications. Shared decision-making is a central aspect of patient counselling but is complicated by significant knowledge gaps. Stakeholder interests can be in conflict; exploring these tensions can help patients to evaluate their options and inform their deliberations. We argue that uniform, evidence-based recommendations for pregnancy after solid organ transplantation are needed. Conducting research, including patient-engaged studies, in this area should be priority for the transplant community.

Roles, Relationships, Resources, and Renal Exchange: Applying Social Capital Theory to Role Effects on Living Kidney Donation Behaviors

Two largely separate schools of sociological theory seek to explain to whom we turn in times of need. The first argues that we turn to network members who occupy socially important roles, highlighting how support behaviors cluster in certain social roles (i.e., role effects). The second argues that we turn to network members possessing relevant resources and with whom we have strong ties. The authors unite these perspectives, examining how role effects on living kidney donation behavior are explained by role groups' endowments of situationally relevant resources and tie strength. The authors analyze two original data sets: a sample of kidney transplantation patients reporting on their social networks (n = 70 patients and 1,421 ties) and a separate sample surveying kidney disease patients' family members (n = 1,560). The authors find that role effects on living kidney donation behavior are largely explained by the conjunction of relevant resources and tie strength, which offers several key lessons for medical support-seeking research.

Sex and gender disparity in kidney transplantation: Historical and future perspectives

Sex and gender disparity exist in various stages of kidney transplantation. Females were found to be less likely to be referred for kidney transplant, complete pre-transplant evaluation, be placed on the waitlist, and receive a kidney transplant compared to their male counterparts. Interestingly, females comprise the majority of living kidney donors. This review explores the biological and psychosocial factors that contribute to sex and gender disparity in kidney transplantation and proposes ways to address the disparity.

Graft survival differences in kidney transplants related to recipient sex and age

Background

In recent years, there has been increasing interest in studying differences in recipient sex in renal disease treatment, access to renal replacement therapy, and subsequent outcomes. Our aim was to find out whether there are differences in outcomes after renal transplantation between female and male kidney transplant recipients in our series, particularly in adults under 60 years of age during long-term follow-up.

Methods

This was a retrospective study of our kidney transplant series (n = 1,101) to compare graft survival depending on the sex of the recipient in the entire series and patients < 60 years of age (n = 687) during long-term follow-up.

Results

We observed no association between recipient sex and graft survival throughout the series, regardless of recipient sex. However, adult female recipients under 60 years of age had lower graft survival than male recipients (p = 0.040). Pre-transplant sensitization (HR 2.438, p = 0.002) and donor age (HR: 1.021, p = 0.017) were the independent variables associated with graft failure.

Conclusion

Female recipients younger than 60 years of age had lower graft survival than male recipients, although there were no gender differences in graft or patient survival in the overall study population. Recipient sex per se was not related to graft failure, but the greater immunological risk in women and more frequent use of expanded criteria donors in female recipients under 60 years of age were the main factors related to their poorer graft survival. Further studies and new strategies are needed to identify these differences and develop the best approach to address them.

An Analysis by the European Committee on Organ Transplantation of the Council of Europe Outlining the International Landscape of Donors and Recipients Sex in Solid Organ Transplantation

Discrepancies in donation and transplantation by sex and gender have previously been reported. However, whether such differences are invariably the inevitable, unintended outcome of a legitimate process has yet to be determined. The European Committee on Organ Transplantation of the Council of Europe (CD-P-TO) is the committee that actively promotes the development of ethical, quality and safety standards in the field of transplantation in Europe. Whilst the ultimate objective is to shed light on the processes underlying potential gender inequities in transplantation, our initial goal was to represent the distribution by sex among organ donors and recipients in the CD-P-TO Member States and observer countries. Our survey confirms previous evidence that, in most countries, men represent the prevalent source of deceased donors (63.3% in 64 countries: 60.7% and 71.9% for donation after brain and circulatory death, respectively). In contrast, women represent the leading source of organs recovered from living kidney and liver donors (61.1% and 51.2% in 55 and 32 countries, respectively). Across countries, most recovered organs are transplanted into men (65% in 57 countries). These observations may be explained, at least in part, by the higher burden of certain diseases in men, childbearing related immune sensitization in women, and donor-recipient size mismatch. Future research should establish whether gender-related socially-constructed roles and socioeconomic status may play a detrimental role reducing the access of women to transplantation.

Contemporary review of heart transplant immunology and immunosuppressive therapy

Background

Survival after heart transplantation (HT) has improved considerably since the first HT was performed in 1967 in Cape Town, South Africa. Understanding immunology behind organ rejection has paved way for advances in the assessment of pre-transplant compatibility, development of newer and more specific immunosuppressive drugs, and management of rejection.

Objectives

Unlike medical therapy for heart failure, transplant protocols vary considerably between different centers. These variations in protocols generally reflect unique population characteristics and the availability of resources. This review article aims to provide a consolidated update on contemporary cardiac transplant medicine. We also aim to highlight local practice and its difference from our international counterparts.

Methods

A literature search was performed on Pubmed and Cochrane Central Register of Controlled Trials to identify trials and review articles that discussed heart transplant immunology and protocols. The International Society for Heart and Lung Transplant (ISHLT) guidelines were also reviewed. We focused on risk factors, prevention strategies, and treatment of cardiac rejection.

Results

A total of 48 articles were selected to provide a comprehensive overview of the contemporary practice of cardiac transplant immunosuppressive therapy. Comparisons were made with local data and practice protocols to highlight key differences.

Conclusion

Heart transplant covers a small subset of cardiac patients and much of the evidence is derived from empirical observations and retrospective analysis. This accounts for the heterogeneity in care and treatment protocols. More studies are needed to select best practices from around the world to further improve outcomes.

Toward an understanding of allogeneic conflict in pregnancy and transplantation

Pregnancy is recognized as a spontaneously acquired state of immunological tolerance by the mother to her semi-allogeneic fetus, but it is a major cause of allosensitization in candidates for organ transplantation. This sensitization, assessed by the presence of anti-HLA IgG, contributes to sex disparity in access to transplantation and increases the risk for rejection and graft loss. Understanding this dual tolerance/sensitization conundrum may lead to new strategies for equalizing access to transplantation among sexes and improving transplant outcomes in parous women. Here, we review the clinical evidence that pregnancy results in humoral sensitization and query whether T cell responses are sensitized. Furthermore, we summarize preclinical evidence on the effects of pregnancy on fetus-specific CD4⁺ conventional, regulatory, and CD8⁺ T cells, and humoral responses. We end with a discussion on the impact of the divergent effects that pregnancy has upon alloantigen re-encounter in the context of solid organ transplantation, and how these insights point to a therapeutic roadmap for controlling pregnancy-dependent allosensitization.

HLA Homozygosity and Likelihood of Sensitization in Kidney Transplant Candidates

Background.

Homozygosity for HLAs has been associated with adverse outcomes after viral infection as well as pregnancy-induced HLA sensitization. We sought to assess the relationship between HLA locus homozygosity and the level of HLA antibody sensitization.

Methods.

We measured sensitization using the calculated panel reactive antibody value for a large cohort of 147 461 patients added to the US OPTN/United Network for Organ Sharing kidney transplant waitlist between December 2014 and December 2019. We used multinomial logistic modeling to compare 62 510 sensitized patients to 84 955 unsensitized controls.

Results.

We found that the number of homozygous HLA loci was strongly associated with the level of sensitization. Within mildly, highly, or extremely sensitized candidates, women displayed a higher relative abundance of HLA homozygosity at multiple HLA loci as compared with men, with attenuation of this effect in Black candidates. In a multivariable logistic model, the number of homozygous HLA loci interacted with female sex but not with other factors associated with sensitization, including recipient ethnicity and a history of prior kidney transplant.

Conclusions.

This study shows that HLA homozygosity is an innate genetic factor that affects the likelihood of HLA sensitization. Further research is needed to identify the immunologic mechanisms that underlie this observation.

Sex and Gender Differences in Kidney Transplantation

Sex and gender often are used interchangeably, but are two distinct entities, with sex being the biological attribute and gender including the social, psychological, and cultural aspects of one's identity. Kidney transplantation has been proven to be the best treatment for end-stage kidney disease, improving both quality of life and life-expectancy for most patients. However, gender disparities in access to and outcomes of kidney transplantation remain despite the plethora of evidence showing the advantages of kidney transplantation to our patients. Data have shown that women are less likely to be waitlisted for a kidney transplant and to receive a deceased donor or a living donor kidney. On the other hand, women are more likely than men to become living kidney donors. Although some state the latter is the result of the female gender to nurture and care for loved ones, others believe this observation is because women often are incompatible with their spouse or child because pregnancy is a strong sensitizing event, which stems from the biological rather than the social differences between the sexes. Influence of sex and gender is not limited to access to kidney transplantation, but rather exist in other areas of transplant medicine, such as the difference observed in transplant outcomes between the sexes, variability in immunosuppression metabolism, and even in more contemporary areas such as recent data showing sex-based differences in outcomes of kidney transplant recipients with coronavirus disease-2019, with males having an increased incidence of acute kidney injury and death.

Sex and gender as predictors for allograft and patient‐relevant outcomes after kidney transplantation

This is a protocol for a Cochrane Review (prognosis). The objectives are as follows:

To evaluate the prognostic effect of the recipient's (i) sex and gender separately (ii) gender as an independent predictor of patient‐relevant outcomes at any time period following kidney or SPK transplantation (Table 1 ) and explore sources of heterogeneity. We aim to evaluate this prognostic effect by (a) clearly defining the relationship between recipient sex/gender and post‐transplantation outcomes, which would involve identifying reasons for variations between sexes and genders, and then (b) quantifying the magnitude of this relationship. 

Insights from the 4C-T Study suggest increased cardiovascular burden in girls with end stage kidney disease before and after kidney transplantation

Mortality in children with kidney failure is higher in girls than boys with cardiovascular complications representing the most common causes of death. Pulse wave velocity (PWV), a measure of vascular stiffness, predicts cardiovascular mortality in adults. Here, PWV in children with kidney failure undergoing kidney replacement therapy was investigated to determine sex differences and potential contributing factors. Two-hundred-thirty-five children (80 girls; 34%) undergoing transplantation (150 pre-emptive, 85 with prior dialysis) having at least one PWV measurement pre- and/or post-transplantation from a prospective cohort were analyzed. Longitudinal analyses (median/maximum follow-up time of 6/9 years) were performed for PWV z-scores (PWVz) using linear mixed regression models and further stratified by the categories of time: pre-kidney replacement therapy and post-transplantation. PWVz significantly increased by 0.094 per year and was significantly higher in girls (PWVz +0.295) compared to boys, independent of the underlying kidney disease. During pre-kidney replacement therapy, an average estimated GFR decline of 4ml/min/1.73m² per year was associated with a PWVz increase of 0.16 in girls only. Higher diastolic blood pressure and low density lipoprotein were independently associated with higher PWVz during pre-kidney replacement therapy in both sexes. In girls post-transplantation, an estimated GFR decline of 4ml/min/1.73m² per year pre-kidney replacement therapy and a longer time (over 12 months) to transplantation were significantly associated with higher PWVz of 0.22 and of 0.57, respectively. PWVz increased further after transplantation and was positively associated with time on dialysis and diastolic blood pressure in both sexes. Thus, our findings demonstrate that girls with advanced chronic kidney disease are more susceptible to develop vascular stiffening compared to boys, this difference persist after transplantation and might contribute to higher mortality rates seen in girls with kidney failure.

Sex Disparity in Transplant: A Problem Hiding in Plain Sight

This month’s installment of “The AJT Report” explores the challenge of sex disparity in transplant and what might be done to address this ongoing problem. We also report on a recent amendment to the U.S. Food and Drug Administration’s COVID-19 vaccine emergency use authorizations that affects solid organ recipients.

Gender disparities in transplantation

PURPOSE OF REVIEW

Transplantation is the life-saving therapy for patients suffering from end-organ failure, and as such, equitable access to transplantation (ATT) is of paramount importance. Unfortunately, gender/sex-based disparities exist, and despite the transplant community's awareness of this injustice, gender/sex-based disparities have persisted for more than two decades. Importantly, no legislation or allocation policy has addressed inequity in ATT that women disproportionately face. In fact, introduction of the model for end-stage liver disease-based liver allocation system in 2002 widened the gender disparity gap and it continues to be in effect today. Moreover, women suffering from kidney disease are consistently less likely to be referred for transplant evaluation and subsequently less likely to achieve a kidney transplant, yet they comprise the majority of living kidney donors.

RECENT FINDINGS

Acknowledging gender/sex-based disparities in ATT is the first step toward interventions aimed at mitigating this long-standing injustice in healthcare.

SUMMARY

This article provides a background of end-stage liver and kidney disease in women, summarizes the existing literature describing the issue of gender disparity in ATT, and identifies potential areas of intervention and future investigation.

Placental Immune Tolerance and Organ Transplantation: Underlying Interconnections and Clinical Implications

The immune system recognizes and attacks non-self antigens, making up the cornerstone of immunity activity against infection. However, during organ transplantation, the immune system also attacks transplanted organs and leads to immune rejection and transplantation failure. Interestingly, although the embryo and placenta are semi-allografts, like transplanted organs, they can induce maternal tolerance and be free of a vigorous immune response. Also, embryo or placenta-related antibodies might adversely affect subsequent organ transplantation despite the immune tolerance during pregnancy. Therefore, the balance between the immune tolerance in maternal-fetal interface and normal infection defense provides a possible desensitization and tolerance strategy to improve transplantation outcomes. A few studies on mechanisms and clinical applications have been performed to explore the relationship between maternal-fetal immune tolerance and organ transplantation. However, up to now, the mechanisms underlying maternal-fetal immune tolerance remain vague. In this review, we provide an overview on the current understanding of immune tolerance mechanisms underlying the maternal-fetal interface, summarize the interconnection between immune tolerance and organ transplantation, and describe the adverse effect of pregnancy alloimmunization on organ transplantation.

Outcome of Husband-to-Wife Kidney Transplantation With Mutual Children: Single Center Experience Using T Cell-Depleting Induction and Review of the Literature

Few data on husband-to-wife transplantations with mutual children (H2W) exist in the current era. We investigated the outcome of H2W transplantations (n = 25) treated with T cell-depleting induction compared to women with prior pregnancies also receiving their first HLA-mismatched kidney transplant, but from a different donor source: (i) other living donor (n = 52) and (ii) deceased donor (n = 120). Seventy-four percent of the women had ≥2 pregnancies; median follow-up time was 5 years. Death-censored allograft survival was significantly lower in the H2W group compared to the other two groups (p = 0.03). Three of four graft losses in the H2W group were due to rejection. 5-year patient survival in the H2W group was high and similar compared to the other living donor group (100 vs. 98%; p = 0.28). The incidence of (sub)clinical antibody-mediated rejection was higher in the H2W group (36 vs. 20 vs. 18%) (p = 0.10). The frequency of infections was similar among the three groups. No immunological parameter was predictive for rejection or graft loss in H2W transplantations. In conclusion, H2W transplantation is a valuable option, but associated with a higher risk for allograft loss due to rejection despite T cell-depleting induction. Further research is required for better risk prediction on an individual patient level.

Plasma cell biology: Foundations for targeted therapeutic development in transplantation

Solid organ transplantation is a life-saving procedure for patients with end-stage organ disease. Over the past 70 years, tremendous progress has been made in solid organ transplantation, particularly in T-cell-targeted immunosuppression and organ allocation systems. However, humoral alloimmune responses remain a major challenge to progress. Patients with preexisting antibodies to human leukocyte antigen (HLA) are at significant disadvantages in regard to receiving a well-matched organ, moreover, those who develop anti-HLA antibodies after transplantation face a significant foreshortening of renal allograft survival. Historical therapies to desensitize patients prior to transplantation or to treat posttransplant AMR have had limited effectiveness, likely because they do not significantly reduce antibody levels, as plasma cells, the source of antibody production, remain largely unaffected. Herein, we will discuss the significance of plasma cells in transplantation, aspects of their biology as potential therapeutic targets, clinical challenges in developing strategies to target plasma cells in transplantation, and lastly, novel approaches that have potential to advance the field.

Memory B Cells in Pregnancy Sensitization

Memory B cells play an important role in immunity to pathogens as these cells are poised to rapidly differentiate into antibody-secreting cells upon antigen re-encounter. Memory B cells also develop over the course of HLA-sensitization during pregnancy and transplantation. In this review, we discuss the potential contribution of memory B cells to pregnancy sensitization as well as the impact of these cells on transplant candidacy and outcomes. We start by summarizing how B cell subsets are altered in pregnancy and discuss what is known about HLA-specific B cell responses given our current understanding of fetal antigen availability in maternal secondary lymphoid tissues. We then review the molecular mechanisms governing the generation and maintenance of memory B cells during infection - including the role of T follicular helper cells - and discuss the experimental evidence for the development of these cells during pregnancy. Finally, we discuss how memory B cells impact access to transplantation and transplant outcomes for a range of transplant recipients.

Navigating the murky waters of maternal fetal tolerance: Put big data at the helm

The last 20 years have seen significant progress in our understanding of the maternal T cell response to the fetus. However, major questions still remain. In this review, we discuss the contribution of Big Data approaches to our evolving understanding of maternal fetal tolerance. This includes investigations which have employed systems immunology, high dimensional mass spectrometry, whole genome transcriptomics, as well as single-cell RNA-sequencing. These studies reveal "new" mechanisms of T cell dysfunction that are conserved across immune responses and highlight the breadth and magnitude of the systemic maternal response to the fetus during pregnancy.

Sex Disparity in Deceased-Donor Kidney Transplant Access by Cause of Kidney Disease

BACKGROUND AND OBJECTIVES

Women with kidney failure have lower access to kidney transplantation compared with men, but the magnitude of this disparity may not be uniform across all kidney diseases. We hypothesized that the attributed cause of kidney failure may modify the magnitude of the disparities in transplant access by sex.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a retrospective cohort study of adults who developed kidney failure between 2005 and 2017 according to the United States Renal Data System. We used adjusted Cox models to examine the association between sex and either access to waitlist registration or deceased-donor kidney transplantation, and tested for interaction between sex and the attributed cause of kidney failure using adjusted models.

RESULTS

Among a total of 1,478,037 patients, 271,111 were registered on the waitlist and 89,574 underwent deceased-donor transplantation. The rate of waitlisting was 6.5 per 100 person-years in women and 8.3 per 100 person-years for men. In adjusted analysis, women had lower access to the waitlist (hazard ratio, 0.89; 95% confidence interval, 0.89 to 0.90) and to deceased-donor transplantation after waitlisting (hazard ratio, 0.96; 95% confidence interval, 0.94 to 0.98). However, there was an interaction between sex and attributed cause of kidney disease in adjusted models (P<0.001). Women with kidney failure due to type 2 diabetes had 27% lower access to the kidney transplant waitlist (hazard ratio, 0.73; 95% confidence interval, 0.72 to 0.74) and 11% lower access to deceased-donor transplantation after waitlisting compared with men (hazard ratio, 0.89; 95% confidence interval, 0.86 to 0.92). In contrast, sex disparities in access to either the waitlist or transplantation were not observed in kidney failure secondary to cystic disease.

CONCLUSIONS

The disparity in transplant access by sex is not consistent across all causes of kidney failure. Lower deceased-donor transplantation rates in women compared with men are especially notable among patients with kidney failure attributed to diabetes.

Self-advocacy is associated with lower likelihood of living donor kidney transplantation

BACKGROUND

The Living Donor Navigator (LDN) Program pairs kidney transplant candidates (TC) with a friend or family member for advocacy training to help identify donors and achieve living donor kidney transplantation (LDKT). However, some TCs participate alone as self-advocates.

METHODS

In this retrospective cohort study of TCs in the LDN program (04/2017-06/2019), we evaluated the likelihood of LDKT using Cox proportional hazards regression and rate of donor screenings using ordered events conditional models by advocate type.

RESULTS

Self-advocates (25/127) had lower likelihood of LDKT compared to patients with an advocate (adjusted hazard ratio (aHR): 0.22, 95% confidence interval (CI): 0.03-1.66, p = 0.14). After LDN enrollment, rate of donor screenings increased 2.5-fold for self-advocates (aHR: 2.48, 95%CI: 1.26-4.90, p = 0.009) and 3.4-fold for TCs with an advocate (aHR: 3.39, 95%CI: 2.20-5.24, p < 0.0001).

CONCLUSIONS

Advocacy training was beneficial for self-advocates, but having an independent advocate may increase the likelihood of LDKT.