Effect of pre-end-stage kidney disease nephrology care on the association between neighborhood poverty and referral for kidney transplantation among patients with end-stage kidney disease

Abstract

Objectives: Socioeconomic inequities in early access to kidney transplantation among patients with end-stage kidney disease (ESKD) are well documented. It is unknown whether these inequities can be mitigated through access to nephrology care prior to starting dialysis. This study evaluated whether pre-ESKD nephrology care meaningfully explained the association between neighborhood poverty and referral for kidney transplantation among patients initiating treatment for ESKD.

Study design and setting: In this retrospective cohort study using United States Renal Data System data (January 1, 2012 to June 30, 2021), we identified 192,318 adults with incident ESKD from dialysis facilities in Southeast, Northeast, New York, and Ohio River Valley US regions. Neighborhood poverty exposure was dichotomized based on zip code poverty rates (≥20% vs 0%-19%), and referral outcomes were assessed from 28 transplant centers. We used marginal structural Cox models with inverse probability of treatment weighting to estimate the direct effect of neighborhood poverty on referral for kidney transplantation, controlling for access to pre-ESKD nephrology care (controlled direct effect).

Results: Findings show that 68% had pre-ESKD nephrology care, and 25% lived in high-poverty areas. Pre-ESKD nephrology care was associated with increased referral (hazard ratio (HR): 1.26, 95% CI: 1.22, 1.30). Adjusted analyses using marginal structural Cox models with inverse probability weighting revealed that pre-ESKD nephrology care did not fully explain the association between neighborhood poverty and referral for kidney transplantation (controlled direct effect HR: 0.87, 95% CI: 0.85, 0.89; total effect HR: 0.90, 95% CI: 0.88, 0.91).

Conclusion: These results underscore the beneficial role of pre-ESKD nephrology care in enhancing transplant referral access. However, persistent disparities linked to neighborhood poverty remain evident. The study emphasizes the continued importance of pre-ESKD nephrology care as a clinical standard for all patients with ESKD. Future research should explore interventions earlier in the kidney disease continuum to address socioeconomic disparities and improve equitable access to kidney transplantation.

Plain language summary: For people with end-stage kidney disease (ESKD), survival depends on either regular dialysis treatments or a kidney transplant. For most people, a kidney transplant offers the best long-term survival and quality of life compared to dialysis. People living in poorer neighborhoods face significant challenges in getting referred for a kidney transplant. Our study aimed to investigate if receiving care from a kidney specialist (nephrologist) before needing dialysis (pre-ESKD nephrology care) could help overcome these income-related disparities in transplant access. We looked at records from nearly 200,000 adults across 4 US regions who started treatment for ESKD. We categorized neighborhoods as "high-poverty" (where 20% or more residents live below the poverty line) or "low-poverty" areas. Using advanced statistical methods, we analyzed how neighborhood poverty affected transplant referral, specifically assessing the role of pre-ESKD nephrology care. Our findings showed that most patients (68%) had seen a nephrologist before dialysis. Seeing a nephrologist was associated with a 26% higher chance of being referred for a transplant. However, even among those who received predialysis nephrology care, living in a high-poverty neighborhood still meant they were 13% less likely to be referred for a transplant. This study highlights that while pre-ESKD nephrology care is beneficial and increases the likelihood of transplant referral, it alone does not fully close the gap in access influenced by neighborhood poverty. To achieve equitable access to kidney transplantation for all patients, future efforts must target broader interventions that address the underlying socioeconomic factors affecting health throughout a patient's kidney disease journey.

Keywords: End-stage kidney disease; Kidney transplant; Neighborhood poverty; Nephrology care; Referral; Socioeconomic factors.