Defining a minimal clinically meaningful difference in 12-month estimated glomerular filtration rate for clinical trials in deceased donor kidney transplantation

HELP-KIDNEY: Health Literacy and Patient Outcomes in Pediatric Kidney Transplant

BACKGROUND

Below adequate health literacy is common and linked to increased risk of adverse health outcomes. Supporting optimal health following kidney transplantation requires the capacity to understand health information and make decisions about care. The impact of low health literacy in the context of pediatric kidney transplant has not previously been studied.

METHODS

This retrospective cohort study sought to determine the relationship between caregiver or patient health literacy and healthcare utilization (outpatient hospital visits, days in hospital) and to explore relationships between health literacy and adherence to tacrolimus (trough level coefficient of variation) and allograft function post-transplant.

RESULTS

Forty patients were included in the analysis. 60% were identified as having adequate literacy using the Newest Vital Sign (NVS). Lower health literacy was significantly correlated with increased healthcare utilization in the first 3 months post-transplant (rs = -0.36, p = 0.024) and in the first year post-transplant (rs = -0.35, p = 0.029). No association was demonstrated between health literacy level and number of days admitted to the hospital (rs = -0.16, p = 0.321), adherence to tacrolimus 6-12 months post-transplant (rs = 0.078, p = 0.68), or change in allograft function 2 years post-transplant (rs = -0.13, p = 0.43).

CONCLUSION

Limited health literacy is common in pediatric kidney transplant recipients and families and is associated with increased frequency of hospital and outpatient clinic department visits early post-transplant. In this small-sized cohort, we did not identify a relationship between health literacy level and hospitalization days, allograft function, or tacrolimus adherence. Larger studies are needed to evaluate the relationship between health literacy and transplant outcomes in children and test interventions that may improve communication and optimize care.

Remote symptom monitoring with patient-reported outcome measures in outpatients with chronic kidney disease (PROKID): a multicentre randomised controlled non-inferiority study

Background

The increasing incidence of chronic kidney disease (CKD) is straining the capacity of outpatient clinics. Remote healthcare delivery might improve CKD follow-up compared with conventional face-to-face follow-up. Patient-reported outcomes (PROs) are used to empower remote follow-up and patient engagement. The consequences of shifting from face-to-face follow-up to remote outpatient follow-up on kidney function, health resource utilisation and quality of life remain unknown.

Methods

We conducted a multicentre pragmatic non-inferiority trial at three outpatient clinics in the Central Denmark Region. A total of 152 incident outpatients with CKD were randomised (1:1:1) to either PRO-based, PRO-telephone follow-up or standard of care (SoC). The primary outcome was the annual change in kidney function measured by the slope of the estimated glomerular filtration rate (eGFR). The non-inferiority margin was an eGFR of 2.85 ml/min/1.73 m2/year. Mean differences were estimated using intention-to-treat (ITT), per protocol and random coefficient models.

Results

Mean eGFR slope differences between PRO-based and SoC were -0.97 ml/min/1.73 m2/year [95% confidence interval (CI) -3.00-1.07] and -1.06 ml/min/1.73 m2/year (95% CI -3.02-0.89) between PRO-telephone and SoC. Non-inferiority was only established in the per-protocol analysis due to CIs exceeding the margin in the ITT group. Both intervention groups had fewer outpatient visits: -4.95 (95% CI -5.82 to -4.08) for the PRO-based group and -5.21 (95% CI -5.95 to -4.46) for the PRO-telephone group. We found no significant differences in quality of life, illness perception or satisfaction.

Conclusion

Differences in the eGFR slope between groups were non-significant and results on non-inferiority were inconclusive. Thus, transitioning to remote PRO-based follow-up requires close monitoring of kidney function. Reducing patients' attendance in the outpatient clinic was possible without decreasing either quality of life or illness perception.ClinicalTrials.gov identifier: NCT03847766.

Palopegteriparatide Treatment Improves Renal Function in Adults with Chronic Hypoparathyroidism: 1-Year Results from the Phase 3 PaTHway Trial

INTRODUCTION

Individuals with chronic hypoparathyroidism managed with conventional therapy (active vitamin D and calcium) have an increased risk for renal dysfunction versus age- and sex-matched controls. Treatments that replace the physiologic effects of parathyroid hormone (PTH) while reducing the need for conventional therapy may help prevent a decline in renal function in this population. This post hoc analysis examined the impact of palopegteriparatide treatment on renal function in adults with chronic hypoparathyroidism.

METHODS

PaTHway is a phase 3 trial of palopegteriparatide in adults with chronic hypoparathyroidism that included a randomized, double-blind, placebo-controlled 26-week period followed by an ongoing 156-week open-label extension (OLE) period. Changes in renal function over 52 weeks (26 weeks blinded + 26 weeks OLE) were assessed using estimated glomerular filtration rate (eGFR). A subgroup analysis was performed with participants stratified by baseline eGFR < 60 or ≥ 60 mL/min/1.73 m2.

RESULTS

At week 52, over 95% (78/82) of participants remained enrolled in the OLE and of those, 86% maintained normocalcemia and 95% achieved independence from conventional therapy (no active vitamin D and ≤ 600 mg/day of calcium), with none requiring active vitamin D. Treatment with palopegteriparatide over 52 weeks resulted in a mean (SD) increase in eGFR of 9.3 (11.7) mL/min/1.73 m2 from baseline (P < 0.0001) and 43% of participants had an increase ≥ 10 mL/min/1.73 m2. In participants with baseline eGFR < 60 mL/min/1.73 m2, 52 weeks of treatment with palopegteriparatide resulted in a mean (SD) increase of 11.5 (11.3) mL/min/1.73 m2 (P < 0.001). One case of nephrolithiasis was reported for a participant in the placebo group during blinded treatment; none were reported through week 52 with palopegteriparatide.

CONCLUSION

In this post hoc analysis of the PaTHway trial, palopegteriparatide treatment was associated with significantly improved eGFR at week 52 in addition to previously reported maintenance and normalization of serum and urine biochemistries. Further investigation of palopegteriparatide for the preservation of renal function in hypoparathyroidism is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04701203.

Longitudinal estimated glomerular filtration rate (eGFR) modeling in long-term renal function to inform clinical trial design in kidney transplantation

Kidney transplantation is the preferred treatment for individuals with end-stage kidney disease. From a modeling perspective, our understanding of kidney function trajectories after transplantation remains limited. Current modeling of kidney function post-transplantation is focused on linear slopes or percent decline and often excludes the highly variable early timepoints post-transplantation, where kidney function recovers and then stabilizes. Using estimated glomerular filtration rate (eGFR), a well-known biomarker of kidney function, from an aggregated dataset of 4904 kidney transplant patients including both observational studies and clinical trials, we developed a longitudinal model of kidney function trajectories from time of transplant to 6 years post-transplant. Our model is a nonlinear, mixed-effects model built in NONMEM that captured both the recovery phase after kidney transplantation, where the graft recovers function, and the long-term phase of stabilization and slow decline. Model fit was assessed using diagnostic plots and individual fits. Model performance, assessed via visual predictive checks, suggests accurate model predictions of eGFR at the median and lower 95% quantiles of eGFR, ranges which are of critical clinical importance for assessing loss of kidney function. Various clinically relevant covariates were also explored and found to improve the model. For example, transplant recipients of deceased donors recover function more slowly after transplantation and calcineurin inhibitor use promotes faster long-term decay. Our work provides a generalizable, nonlinear model of kidney allograft function that will be useful for estimating eGFR up to 6 years post-transplant in various clinically relevant populations.

Early Estimated Glomerular Filtration Rate Trajectories After Kidney Transplant Biopsy as a Surrogate Endpoint for Graft Survival in Late Antibody-Mediated Rejection

Background

Late antibody-mediated rejection (ABMR) after kidney transplantation is a major cause of long-term allograft loss with currently no proven treatment strategy. Design for trials testing treatment for late ABMR poses a major challenge as hard clinical endpoints require large sample sizes. We performed a retrospective cohort study applying commonly used selection criteria to evaluate the slope of the estimated glomerular filtration rate (eGFR) within an early and short timeframe after biopsy as a surrogate of future allograft loss for clinical trials addressing late ABMR.

Methods

Study subjects were identified upon screening of the Vienna transplant biopsy database. Main inclusion criteria were (i) a solitary kidney transplant between 2000 and 2013, (ii) diagnosis of ABMR according to the Banff 2015 scheme at >12 months post-transplantation, (iii) age 15-75 years at ABMR diagnosis, (iv) an eGFR > 25 mL/min/1.73 m2 at ABMR diagnosis, and (v) a follow-up for at least 36 months after ABMR diagnosis. The primary outcome variable was death-censored graft survival. A mixed effects model with linear splines was used for eGFR slope modeling and association of graft failure and eGFR slope was assessed applying a multivariate competing risk analysis with landmarks set at 12 and 24 months after index biopsy.

Results

A total of 70 allografts from 68 patients were included. An eGFR loss of 1 ml/min/1.73 m2 per year significantly increased the risk for allograft failure, when eGFR slopes were modeled over 12 months [HR 1.1 (95% CI: 1.01-1.3), p = 0.020] or over 24 months [HR 1.3 (95% CI: 1.1-1.4), p = 0.001] after diagnosis of ABMR with landmarks set at both time points. Covariables influencing graft loss in all models were histologic evidence of glomerulonephritis concurring with ABMR as well as the administration of anti-thymocyte globulin (ATG) at the time of transplantation.

Conclusion

Our study supports the use of the eGFR slope modeled for at least 12 months after biopsy-proven diagnosis of late ABMR, as a surrogate parameter for future allograft loss. The simultaneous occurrence of glomerulonephritis together with ABMR at index biopsy and the use of ATG at the time of transplantation-likely representing a confounder in pre-sensitized recipients-were strongly associated with worse transplant outcomes.

Defining a minimal clinically meaningful difference in 12-month estimated glomerular filtration rate for clinical trials in deceased donor kidney transplantation

BACKGROUND

A Minimal Clinically Meaningful Difference (MCMD) has not been defined for Estimated glomerular filtration rate (eGFR). Our goal was to define the MCMD for eGFR anchored to kidney graft failure.

METHODS

A systematic review of studies with 12-month eGFR and subsequent renal graft failure was conducted. For observational studies, we calculated hazard ratio (HR) differences between adjacent eGFR intervals weighted by population distribution. Interventional trials yielded therapeutically induced changes in eGFR and failure risk. OPTN data analysis divided 12-month eGFR into bands for Cox regressions comparing adjacent eGFR bands with a death-censored graft survival outcome.

RESULTS

Observational studies indicated that lower eGFR was associated with increased death-censored graft failure risk; each 5 ml/min/1.73 m2 12-month eGFR band associated with a weighted incremental HR = 1.12 to 1.23. Clinical trial data found a 5 ml/min/1.73 m2 difference was associated with incremental HR = 1.16 to 1.35. OPTN analyses showed weighted mean HRs across 10, 7, and 5 ml/min/1.73 m2 bands of 1.47, 1.30, and 1.19.

CONCLUSIONS

A 5 ml/min/1.73 m2 difference in 12-month eGFR was consistently associated with ~20% increase in death-censored graft failure risk. The magnitude of effect has been interpreted as clinically meaningful in other disease states and should be considered the MCMD in renal transplantation clinical trials.