Hispanics, the largest ethnic minority group in the United States, experience faster progression of chronic kidney disease to kidney failure compared with non-Hispanic White individuals. A recently published manuscript in AJKD compared kidney transplant outcomes between Hispanic individuals and non-Hispanic White individuals to gain insights into these health disparities. AJKDBlog’s Interviews Editor, Timothy Yau (@Maximal_Change), sat down with one of the authors of the study, Sixto Giusti (@GiustiSix), to discuss the implications of their paper.

Dr. Sixto Giusti is a transplant nephrologist at the University of Colorado Anschutz Medical Campus. He is dedicated to advancing health equity and championing access to transplantation for marginalized communities.

 

AJKD Blog: Disparities in kidney disease health, outcomes on dialysis, and access to kidney transplants have been well reported in the US, but these inequities often are highlighted in Black patients. Can you give us a snapshot of kidney disease and its impact on Hispanic patients, the population your study focused on?

Dr. Giusti: Hispanics have a disproportionately high burden of CKD and a 1.3-fold faster progression to kidney failure compared with non-Hispanic White (NHW) individuals. This is probably due to several factors including social determinants of health (e.g. lower income, education level, poor housing conditions, etc.), metabolic risk factors (greater prevalence of cardiovascular disease risk factors, including obesity and diabetes, hypertension, as well as CKD-related complications), and lack of access to care.

For example, despite diabetes being the main cause of CKD and kidney failure among Hispanic individuals (currently affects 20% of US Hispanic individuals) and that progression can be prevented with lifestyle changes and certain medications, Hispanic individuals continue to have suboptimal control of diabetes and hypertension, low use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and low awareness of having CKD. Similarly, two previous major research initiatives, Chronic Renal Insufficiency Cohort (CRIC) study and Hispanic Chronic Renal Insufficiency Cohort (H-CRIC) study, found that Hispanics have significantly increased manifestation of kidney dysfunctions in terms of eGFR, urine protein quantification, left ventricular hypertrophy, and adverse metabolic biomarkers than Whites.

Improved healthcare access among Hispanic CKD patients can reduce this burden.  As Pereira et al reported, it is estimated that 40% of Hispanic individuals living in the United States have no health insurance, and many others are underinsured and have large copays that limit their access to doctor’s visits, medical tests, and treatments. Social factors—including poverty and economic instability, limited health literacy and English-language proficiency, lack of access to transportation, lack of childcare, and lack of paid time off—are additional barriers that prevent many Latinx people from accessing health care. Even when health care services are available to Latinx individuals, other factors—including low trust in the care provider and/or medical system, provider bias, communication barriers, and cultural differences—can result in inadequate care.

Consequently – to quote our paper – Hispanic individuals are less likely than NHW individuals to receive predialysis nephrology care or be referred for a kidney transplant.​​ Even when they have established dialysis care, Hispanic individuals experience a longer delay in becoming active on the waitlist.​​ After they are placed on the waitlist, Hispanic individuals experience longer waiting times on dialysis for a kidney transplant, which has been associated with a higher rate of death, and have lower rates of living donors when compared with NHW individuals.

AJKD Blog: Before we jump into your paper, you mention that prior studies have suggested that kidney transplants in Hispanic recipients may do better than their non-Hispanic white counterparts. One unique aspect of your paper looked at recipients and their citizenship status in the US. Has this been explored in other papers, and how does yours differ from previous research?

Dr. Giusti: Other studies have looked at kidney transplant outcomes in non us citizens as follows. In a study of over 10,000 patients, of whom 17% were either permanent residents or nonresident aliens (ie, undocumented immigrants), Shen et al​​ found that the select group of insured nonresident aliens who underwent transplantation with Medicaid had similar outcomes as US citizens with Medicaid. Nonresident aliens had a lower unadjusted graft loss risk than US citizens (HR, 0.48 [95% CI, 0.35-0.65]). In this study, 71% of the transplants happened in California. More recently, Menon and colleagues, using two national US registries, showed that despite the barriers to kidney transplantation faced by presumed unauthorized immigrants and residents in the US, better post-transplant outcomes for presumed unauthorized immigrants compared to citizens persisted, even after accounting for differences in patient characteristics. In our study, we found that non-US citizens Hispanic patients (27.5% of Hispanic patients) also demonstrated lower adjusted hazard of death and composite when compared with NHW recipients, a finding that had not been previously reported with SRTR data. Findings from these studies provide convincing evidence that we should support providing coverage for kidney transplantation in this patient population.

AJKD Blog: What were the major groups and outcomes you were interested in, and what databases did you use to collect the data?

Dr. Giusti: Great question, here is an excerpt from the article that should help answer that: We used SRTR data and used the race and ethnicity categories provided in SRTR and grouped them as follows: non-Hispanic White (White), Black (Black or African American), Hispanic (Hispanic/Latino), and Other (all other races/ethnicities). The citizenship categories were combined as per OPTN guidelines: “non-US citizen/US resident,” “non-US citizen/non-US resident who traveled to the United States for transplant,” and “non-US citizen/non-US resident who traveled to the United States for reason other than transplant.”

The main outcomes were time to posttransplant mortality and the composite outcome of graft failure, retransplant, or death. As a sensitivity analysis, graft failure, defined as retransplant or return to dialysis, was also evaluated with death as a competing risk. As a secondary sensitivity analysis, we also evaluated mortality censored at the transplant recipient cohort censoring date and the last graft follow-up date to avoid potential bias of Hispanic loss to follow-up through the Social Security death system.

AJKD Blog: Table 1 shows a breakdown of characteristics by race and ethnicity. Were there any big differences you can point out when looking across the numbers?

Dr. Giusti: As we reported in the article, Hispanics represented 17.1% of the patient’s sample; 72.5% were US citizens, 23% were non-US citizens/US residents, and 4.5% were non-US citizens/non-US residents.

In our study, Hispanic patients were younger than NHW (48.8 vs 53.5). Only 28% of Hispanics had private health insurance compared with 46% of NHW individuals. Also, 68% of Hispanic recipients had a high school education or less compared with 37.2% of NHW individuals, and the median SDI for Hispanic recipients was 77 compared with 38 for NHW individuals.

When compared with NHW recipients, Hispanics had to wait longer on the waitlist for a transplant (18.4 months versus 12.7), had spent more time on dialysis at the time of transplant (48.6 months of dialysis vs 27.5), and had lower percentages of preemptive transplantation (9.9% vs 26.3%) and living donation (27.3% vs 43.6%).

AJKD Blog: How did the outcomes for Hispanics differ from their NHW recipients?  Did citizenship or US residency make any difference as well?

Dr. Giusti: Another great question, and here is what we found as reported in the article: When compared with NHW individuals, Hispanics had a significantly lower hazard of death (0.83 [95% CI, 0.80-0.86]) and the composite outcome (0.94 [95% CI, 0.90-0.97]) in unadjusted Cox proportional hazards models. In adjusted models, Hispanics had a lower hazard of death and the composite outcome compared with NHW recipients (HR, 0.70 [95% CI, 0.67-0.73]; and HR, 0.79 [95% CI, 0.76-0.82], respectively). Hispanics who were non-US citizens/US residents also had a lower hazard of death (0.68 [95% CI, 0.63-0.74]) and the composite outcome (0.73 [95% CI, 0.68-0.78]) compared with NHW individuals.

Overall unadjusted survival and composite outcome-free survival. Composite outcome: graft failure or death. Abbreviation: NHW=non-Hispanic White. Figure 2 from Giusti et al, © National Kidney Foundation.

AJKD Blog: Given many of the social and economic challenges in the Hispanic population, one might expect a lower graft and patient survival in this population. What are explanations for the paradoxical findings in this study and the previous research in this field?

Dr. Giusti: As we discuss in the paper, Gordon et al​​ attributed ethnic advantages in kidney transplant outcomes to the Hispanic paradox. In their work, they attributed this ethnic advantage to several factors including Hispanic recipients being younger (and hence with fewer comorbidities) and having a higher proportion of living donors than deceased donors compared with other ethnic minorities, a higher proportion of standard criteria donors than expanded criteria donors, and a higher proportion of primary transplant than repeat transplants.

In our study, Hispanic patients were, in fact, younger at the time of transplantation and had higher rates of living donation when compared with other minorities (27.3% for Hispanic, 14.8% for Black, and 43.6% for NHW individuals). Among Hispanics, 10.1% of patients had prior kidney transplants versus 14% for NHW individuals. By contrast, Hispanic recipients had a lower proportion of living donations versus NHW individuals (27.3% vs 43.6%) and had similar Kidney Donor Profile Index (KDPI) and acceptance of high KDPI offers.

More recently, Desai et al​​ postulated other possible explanations for this paradox, including an incomplete and/or suboptimal ascertainment of comorbid condition burden among Hispanics and NHW in the available studies (ie, measurement error and ascertainment bias), salmon bias (ie, those Hispanics who complete a return migration to their country of origin may do so because they are sicker than those who remain in the United States), differences in inflammation and nutrition, and psychosocial/sociocultural factors.

Other potential factors that could explain the improved outcomes on the Hispanic population include migration bias (ie, younger and healthier individuals more likely to immigrate vs sicker/older individuals), selection bias (healthier patients were selected, and sicker/older individuals were never referred for transplant), strong social ties (ie, extensive family support), or resilience. Such explanations are just speculations by the authors.

In our study, we attempted to correct for the potential bias due to reimmigration and lack of mortality capture by also censoring at the last center graft follow-up evaluation, and we still found a lower adjusted mortality hazard for Hispanics compared with NHW. Ultimately, these findings and observations suggest that there are possibly more factors explaining differences in outcomes that are not directly available in national registries, and that a thorough evaluation is needed to understand reasons behind this Hispanic paradox. Exploring potential sources of selection bias, access to treatment, and outcomes at all stages of CKD and kidney failure will lead to a better understanding of these unique dynamics that can contribute to improving care and outcomes for diverse patient populations.

AJKD Blog: Based on the results of this study, what do your findings suggest when it comes to kidney transplant patterns in this country, and how does it potentially impact future interventions and policies?

Dr. Giusti: First, quoting directly from our results:  we can conclude that despite many social and economic challenges and irrespective of their citizenship status, Hispanic transplant recipients had superior posttransplant outcomes compared to NHW transplant recipients. These results suggest that Hispanic patients getting a transplant might be a highly selected group and the possibility that the greatest need in addressing disparities in this patient population lies in the period before transplantation. Future studies that focus on improving access to transplantation in this population and interventions and policies specifically designed to alleviate disparities, particularly in the earlier stages of kidney disease, are warranted.

Second, in regards to the findings of non-US citizens, the results should support national policy changes to make access to transplantation more equitable to this patient population, in accordance to the National Organ Transplant Act of 1984.

To view Giusti et al [subscription required], please visit AJKD.org:
Title: Evaluating Long-Term Outcomes Among Hispanic Kidney Transplant Recipients
Authors: Sixto Giusti, Susana Arrigain, Rocio Lopez, Elizabeth Pomfret, Lilia Cervantes, Jesse D. Schold
DOI: 10.1053/j.ajkd.2025.01.013