Prevalence of Gout in the Surviving United States Solid Organ Transplantation Population

Monosodium Urate Crystal Depletion and Bone Erosion Response in Kidney Transplant Recipients With Uncontrolled Gout Treated With Pegloticase: PROTECT Serial Dual-Energy Computed Tomography Findings

Background

Hyperuricemia and gout are associated with poor outcomes in kidney transplant (KT) recipients, including graft failure. The PROspective sTudy of pEglotiCase in Transplant patients (PROTECT) trial showed high urate-lowering efficacy of pegloticase in immunosuppressed KT recipients with uncontrolled gout. Here, we report serial dual-energy computed tomography (DECT) findings in PROTECT participants.

Methods

KT recipients with uncontrolled gout (serum urate [SU] ≥7 mg/dL, refractory to/intolerant of oral urate-lowering therapy, and symptoms [≥2 flares per year, tophi, and/or gouty arthritis]) and serial DECT imaging were included. Patients were required to have an estimated glomerular filtration rate ≥15 mL/min/1.73 m2 >1 y posttransplant. All patients received pegloticase for ≤24 wk (8 mg infusion every 2 wk) and underwent imaging (screening, week 14, week 24). DECT images were acquired with standard protocols and postprocessed for monosodium urate (MSU) volume (VMSU) using default settings. Regions (bilateral hands/wrists, feet/ankles, knees) with paired screening/week 24 images and screening VMSU ≥0.5 cm3 (minimized DECT-artifact influence) were included.

Results

Eight patients underwent DECT imaging (all men; age: 52.3 ± 11.2 y, time since KT: 18.7 ± 6.9 y, estimated glomerular filtration rate: 45.6 ± 12.4 mL/min/1.73 m2, SU: 10.4 ± 2.1 mg/dL). Six patients (75%) completed the study and received 24 wk of pegloticase therapy, and 2 prematurely discontinued because of COVID-exposure concerns. Of the 6 patients, 4 met imaging inclusion criteria and were included in the analysis. All 4 patients had sustained SU-lowering during month 6 with marked VMSU reduction at week 24 (mean change in VMSU: -98.9%±1.7% [5 imaging regions]). Numerous bone erosions were present in all patients with MSU-adjacent, unknown mineral deposit-adjacent, and deposit-independent erosions. Imaging suggested osteopenia/osteomalacia in 5 patients (83%). After pegloticase treatment, MSU-adjacent erosions decreased in size in a single patient with no DECT evidence of osteopenia/osteomalacia.

Conclusions

Consistent with prior studies in nontransplant populations, marked depletion of deposited MSU occurred in KT recipients with uncontrolled gout after pegloticase therapy. However, unlike transplant-naive patients, subsequent bone erosion remodeling was not widely observed in urate-adjacent erosions, perhaps due to overall poor bone health in this patient population.

Clinical Trial Registration

ClinicalTrials.gov: NCT04087720.

Quality of life improvements and clinical assessments in kidney transplant recipients undergoing pegloticase treatment for uncontrolled gout: findings of the phase 4 PROTECT clinical trial

Introduction

Gout is 12-times more prevalent in kidney transplant (KT) recipients than in non-transplanted population. We report quality-of-life (QOL) and clinical assessment findings from the PROTECT trial examining pegloticase efficacy and safety in KT recipients with uncontrolled gout.

Methods

Patients with serum urate (SU) ≥7 mg/dL, oral urate-lowering therapy refractory/intolerant, and with one of the following were enrolled: ≥2 flares/year, unresolving tophi, or chronic gouty arthritis. Patients were ≥1 year post-transplant, with a graft eGFR ≥15 ml/min/1.73m2 and received stable immunosuppression. Pegloticase was administered for 24 weeks. QOL endpoints included the Health Assessment Questionnaire (HAQ; Disability Index [DI], Health, Pain) and Physician Global Assessment (PhGA) of Gout. Key clinical assessments included proportion of patients with resolution of ≥1 tophus and change from baseline in blood pressure (BP) at Week 24.

Results

Twenty KT recipients (85.0% male, age: 53.9±10.9 years, BMI: 30.6±7.2 kg/m2, eGFR: 45.8±11.9 ml/min/1.73 m2, time since kidney transplant: 14.6±6.9 years) were included. The primary endpoint was achieved with 89% of patients reaching and maintaining a SU of <6 mg/dL during Month 6. Meaningful improvements occurred over 24 weeks of treatment in all QOL measures (mean [95% CI] change from baseline: HAQ-DI: -0.3 [-0.6, 0.1], HAQ-Pain: -35.5 [-54.5, -16.5], HAQ-Health: -22.4 [-39.5, -5.2], PhGA: -2.4 [-3.7, -1.1]) and clinical assessments (≥1 tophus resolved: 3 of 7 with tophi at baseline [42.9%]; change from baseline in mean arterial BP: -6.8 [-12.5, -1.0] mmHg).

Conclusions

Given the high prevalence of uncontrolled gout in KT recipients, proper SU management is of particular importance. Additionally, intensive urate-lowering with pegloticase may have clinical and QOL benefits.

Acute Lung Injury in Immunocompromised Patients

Acute lung injury is a devastating complication when occurring in immunocompromised patients. The incidence appears to be increasing as more patients survive for longer in this susceptible state. Being aware of potential causes of acute lung injury may lead to earlier recognition and diagnosis. Infection is a common cause of acute lung injury and needs to be considered in the diagnostic algorithm. Management involves use of supportive ventilatory strategies and potentially pharmacologic therapies.

Mild hyperthermia enhanced synergistic uric acid degradation and multiple ROS elimination for an effective acute gout therapy

BACKGROUND

Acute gouty is caused by the excessive accumulation of Monosodium Urate (MSU) crystals within various parts of the body, which leads to a deterioration of the local microenvironment. This degradation is marked by elevated levels of uric acid (UA), increased reactive oxygen species (ROS) production, hypoxic conditions, an upsurge in pro-inflammatory mediators, and mitochondrial dysfunction.

RESULTS

In this study, we developed a multifunctional nanoparticle of polydopamine-platinum (PDA@Pt) to combat acute gout by leveraging mild hyperthermia to synergistically enhance UA degradation and anti-inflammatory effect. Herein, PDA acts as a foundational template that facilitates the growth of a Pt shell on the surface of its nanospheres, leading to the formation of the PDA@Pt nanomedicine. Within this therapeutic agent, the Pt nanoparticle catalyzes the decomposition of UA and actively breaks down endogenous hydrogen peroxide (H2O2) to produce O2, which helps to alleviate hypoxic conditions. Concurrently, the PDA component possesses exceptional capacity for ROS scavenging. Most significantly, Both PDA and Pt shell exhibit absorption in the Near-Infrared-II (NIR-II) region, which not only endow PDA@Pt with superior photothermal conversion efficiency for effective photothermal therapy (PTT) but also substantially enhances the nanomedicine's capacity for UA degradation, O2 production and ROS scavenging enzymatic activities. This photothermally-enhanced approach effectively facilitates the repair of mitochondrial damage and downregulates the NF-κB signaling pathway to inhibit the expression of pro-inflammatory cytokines.

CONCLUSIONS

The multifunctional nanomedicine PDA@Pt exhibits exceptional efficacy in UA reduction and anti-inflammatory effects, presenting a promising potential therapeutic strategy for the management of acute gout.

Meta-analysis and systematic review of gout prevalence in the heart/lung transplantation population

Introduction

Gout may complicate solid organ transplantation with potentially serious consequences. An accurate prevalence of gout in this population is unknown.

Objectives

This study aimed to estimate the prevalence of gout in the heart and/or lung transplantation population through a systematic review and meta-analysis.

Methods

MEDLINE, Embase, PsycINFO, CENTRAL and Cochrane Library (inception to February 2022) were searched for studies that reported the prevalence and/or incidence of gout in heart and/or lung transplant recipients. Two authors extracted outcomes data. Data were pooled using a random effects model. Overall quality of evidence was assessed using GRADE. Primary outcomes were the prevalence of pre- or post-transplant gout expressed as a prevalence rate (95% CI). Secondary outcomes included risk factors for gout, adverse events, and therapeutic complications of gout treatment.

Results

Ten studies were included. Gout prevalence (PR) was 8% pre-transplant (PR = 0.08; 95% CI: 0.05-0.12; 4 studies n = 651) and 6% post-transplant (PR = 0.06; 95% CI: 0.06-0.06; 10 studies n = 45,298). Post-transplant gout prevalence in heart transplant recipients was almost three times higher than lung transplant recipients (PR = 0.16; 95% CI: 0.13-0.20 vs. PR = 0.06; 95% CI: 0.05-0.06 respectively). Patients with a pre-transplant history of gout had a higher risk of developing post-transplant gout than patients without (RR = 3.61; 95% CI: 2.19-5.95). Factors associated with gout and outcomes for heart and/or lung transplant recipients with gout were comprehensively reviewed from the included studies.

Conclusion

Gout is highly prevalent in heart and/or lung transplant patients. Pre-transplant gout is predictive of developing symptomatic post-transplant gout. This has significant implications for management of heart/lung transplant patients.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42020190632).

Pegloticase efficacy and safety in kidney transplant recipients; results of the phase IV, open-label PROTECT clinical trial

INTRODUCTION

Kidney transplant (KT) recipients have a high prevalence and severity of gout. Pegloticase (pegylated recombinant uricase) rapidly metabolizes serum uric acid (sUA), and its efficacy is not impacted by kidney function.

METHODS

This open-label, Phase 4 trial (PROTECT NCT04087720) examined safety and efficacy of pegloticase in 20 participants with KT > 1 year prior to enrollment and with uncontrolled gout (sUA ≥7 mg/dL, intolerance/inefficacy to urate lowering therapy, and ≥1 of the following: tophi, chronic gouty arthritis, ≥2 flares in past year) and functioning KT (estimated glomerular filtration rate [eGFR] ≥15 mL/min/1.73 m2 ) on stable immunosuppression therapy.

RESULTS

The primary endpoint was sUA response during month 6 (sUA < 6 mg/dL for ≥80% of time). The study enrolled 20 participants (mean ± SD); age: 53.9 ± 10.9 years, time since KT: 14.7 ± 6.9 years, sUA: 9.4 ± 1.5 mg/dL, gout duration: 8.4 ± 11.6 years; all on ≥2 stable doses of immunosuppression agents. Pegloticase (8 mg intravenous every 2 weeks) in KT recipients with uncontrolled gout showed a high response rate of 89% (16/18 responders). Two participants discontinued treatment solely due to COVID-19 concerns prior to month 6 were not included in the primary analysis. Pegloticase exposures were higher than those historically observed with pegloticase monotherapy, and no anaphylaxis or infusion reaction events occurred during the study.

CONCLUSIONS

This improved response rate to pegloticase in the KT population reflects observations from other trials and reports on immunomodulation with pegloticase. As the KT population has a high prevalence of gout and limitations with oral urate lowering medication options, these findings suggest a potential option for uncontrolled gout therapy in KT participants.

Serum uric acid levels in kidney transplant recipients: A cause for concern? A review of recent literature

The impact of elevated serum uric acid levels i.e., hyperuricemia, on native and transplant chronic kidney disease progression has been debated. This literature review presents an analysis of multiple studies exploring the relationship between serum uric acid levels and kidney transplant outcomes. The review includes a summary of the pathophysiology of hyperuricemia and gout, a review of urate-lowering therapies, and an appraisal of multiple studies examining the association or lack thereof between serum uric acid level and kidney transplant outcomes. Based on these studies, elevated serum uric acid levels may contribute to CKD progression in kidney transplant recipients. In this review, we also summarize current literature to highlight risk factors associated with hyperuricemia as well as the need for further investigation to monitor and manage hyperuricemia in kidney transplant recipients.

The Management of Gout in Renal Disease

Gout, a debilitating inflammatory arthritis, currently affects more than 9 million Americans. Hyperuricemia, the laboratory abnormality associated with the development of gout, also occurs in a significant number of patients with chronic kidney disease (CKD), a condition that affects approximately 14% of the US population. Several recent studies have attempted to provide a definitive link between the presence of hyperuricemia and progression of CKD; however, the treatment of asymptomatic hyperuricemia in CKD is not supported by recent randomized controlled trials. The pharmacology of acute gout flares and urate lowering is complicated in patients who also have evidence of CKD, primarily because of an increased risk of medication toxicity. Recipients of kidney transplants are particularly at risk of debilitating gout and medication toxicity. We review the available data linking CKD, gout, and hyperuricemia, providing practice guidelines on managing gout in CKD patients and kidney transplant recipients. We advocate for much greater involvement of nephrologists in the management of gout in renal patients.

New-Onset Gout as an Independent Risk Factor for Returning to Dialysis After Kidney Transplantation

Background.

The causal relationship between gout and renal transplant outcomes is difficult to assess due to multiple interacting covariates. This study sought to estimate the independent effect of new-onset gout on renal transplant outcomes using a methodology that accounted for these interactions.

Methods.

This study analyzed data on patients in the US Renal Data System (USRDS) who received a primary kidney transplant between 2008 and 2015. The exposure was new-onset gout, and the primary endpoint was returning to dialysis >12 months postindex date (transplant date). A marginal structural model (MSM) was fitted to determine the relative risk of new-onset gout on return to dialysis.

Results.

18 525 kidney transplant recipients in the USRDS met study eligibility. One thousand three hundred ninety-nine (7.6%) patients developed new-onset gout, and 1420 (7.7%) returned to dialysis >12 months postindex. Adjusting for baseline and time-varying confounders via the MSM showed new-onset gout was associated with a 51% increased risk of return to (RR, 1.51; 95% CI, 1.03-2.20).

Conclusions.

This finding suggests that new onset gout after kidney transplantation could be a harbinger for poor renal outcomes, and to our knowledge is the first study of kidney transplant outcomes using a technique that accounted for the dynamic relationship between renal dysfunction and gout.

Medical care of liver transplant patients

INTRODUCTION

Liver transplantation is a life-changing event for patients and survival following transplantation has improved significantly since the first transplantation in 1967. Following liver transplantation, patients face a unique set of healthcare management decisions including transplantation-specific complications, recurrence of primary liver disease, as well as metabolic and malignancy concerns related to immunosuppression. As more patients with liver disease receive transplantation and live longer, understanding and managing these patients will require not only transplant specialist but also local subspecialist and primary care physicians.

AREAS COVERED

This review covers common issues related to the management of patients following liver transplantation including immunosuppression, liver allograft dysfunction, metabolic complications, as well as routine health maintenance such as immunizations and cancer screening.

EXPERT OPINION

Optimizing medical care for patients following liver transplant will benefit from ensuring all providers, not just transplant specialist, have a basic understanding of the common issues encountered in the post-transplant patient. This review provides an overview of common healthcare concerns and management options for patients following liver transplantation.

A Retrospective Cohort Study of the Effect of Gout on Mortality Among Patients with a History of Kidney Transplantation

Background

Kidney transplantation is associated with increased prevalence of gout. However, evidence of the effect of gout on long-term kidney transplantation outcomes is mixed. This study examined mortality risk among patients with a history of kidney transplantation with vs. without gout.

Material/Methods

A retrospective study was conducted using Medicare Fee-for-Service administrative claims of patients with a history of kidney transplantation. Cox proportional hazards models determined the effect of gout on all-cause mortality, controlling for confounders, including comorbid mortality risk, via the Charlson Comorbidity Index. Because the relationships between gout and components of the Charlson Comorbidity Index are also debated, 3 different model assumptions were used: 1) gout shares a common cause with these comorbidities, 2) gout is upstream of these comorbidities, 3) the effect of gout on mortality is modified by these comorbidities.

Results

Gout increased the risk of all-cause mortality in the unadjusted model (hazard ratio: 1.44, 95% CI 1.27–1.63) and after adjustment for demographics and transplant vintage (hazard ratio: 1.16, 95% CI 1.02–1.32). Gout was not a significant risk after adjustment for baseline Charlson Comorbidity Index (hazard ratio: 1.03, 95% CI 0.90–1.17). Gout was associated with greater mortality among patients without baseline comorbidities (Charlson Comorbidity Index=0; hazard ratio: 3.48, 95% CI 1.27–9.57) in the stratified model.

Conclusions

Among patients with a history of kidney transplantation, gout did not have an independent effect on all-cause mortality. However, gout was a predictor of mortality among patients with no comorbidities, suggesting that gout is an early warning sign of poor health in kidney transplantation patients.