Continuous Kidney Replacement Therapy and Survival in Children and Young Adults: Findings From the Multinational WE-ROCK Collaborative.

RATIONALE & OBJECTIVE: There are limited studies describing the epidemiology and outcomes in children and young adults receiving continuous kidney replacement therapy (CKRT). We aimed to describe associations between patient characteristics, CKRT prescription, and survival. STUDY DESIGN: Retrospective multicenter cohort study. SETTING & PARTICIPANTS: 980 patients aged from birth to 25 years who received CKRT between 2015 and 2021 at 1 of 32 centers in 7 countries participating in WE-ROCK (Worldwide Exploration of Renal Replacement Outcomes Collaborative in Kidney Diseases). EXPOSURE: CKRT for acute kidney injury or volume overload. OUTCOMES: Death before intensive care unit (ICU) discharge. ANALYTICAL APPROACH: Descriptive statistics. RESULTS: Median age was 8.8 years (IQR, 1.6-15.0), and median weight was 26.8 (IQR, 11.6-55.0) kg. CKRT was initiated a median of 2 (IQR, 1-6) days after ICU admission and lasted a median of 6 (IQR, 3-14) days. The most common CKRT modality was continuous venovenous hemodiafiltration. Citrate anticoagulation was used in 62%, and the internal jugular vein was the most common catheter placement location (66%). 629 participants (64.1%) survived at least until ICU discharge. CKRT dose, filter type, and anticoagulation were similar in those who did and did not survive to ICU discharge. There were apparent practice variations by institutional ICU size. LIMITATIONS: Retrospective design; limited representation from centers outside the United States. CONCLUSIONS: In this study of children and young adults receiving CKRT, approximately two thirds survived at least until ICU discharge. Although variations in dialysis mode and dose, catheter size and location, and anticoagulation were observed, survival was not detected to be associated with these parameters. PLAIN-LANGUAGE SUMMARY: In this large contemporary epidemiological study of children and young adults receiving continuous kidney replacement therapy in the intensive care unit, we observed that two thirds of patients survived at least until ICU discharge. However, patients with comorbidities appeared to have worse outcomes. Compared with previously published reports on continuous kidney replacement therapy practice, we observed greater use of continuous venovenous hemodiafiltration with regional citrate anticoagulation.

Prevention and management of CMV infection in pediatric solid organ transplant recipients.

Human cytomegalovirus (CMV) remains one of the most common opportunistic infections following solid organ transplantation in children. CMV causes morbidity and mortality through direct tissue-invasive disease and indirect immunomodulatory effects. In recent years, several new agents have emerged for the prevention and treatment of CMV disease in solid organ transplant recipients. However, pediatric data remain scarce, and many of the treatments are extrapolated from the adult literature. Controversies exist about the type and duration of prophylactic therapies and the optimal dosing of antiviral agents. This review provides an up-to-date overview of treatment modalities used to prevent and treat CMV disease in solid organ transplant (SOT) recipients.

BK DNAemia in pediatric kidney transplant recipients: Predictors and outcomes.

BACKGROUND: Pediatric data on risk factors and the clinical course of BK DNAemia are limited. We aimed to determine the effects of BK DNAemia on transplant outcomes and delineate the safety and efficacy of various treatment approaches. METHODS: This retrospective-cohort study included 161 transplants (age ≤ 21 years) performed at a single center between 1/1/2012 and 1/1/2020. We used Cox proportional models to evaluate the effects of BK DNAemia on patient survival (PS), graft survival (GS), and acute rejection (AR), using BK as a time-dependent covariate. We also assessed the effects of pharmacological intervention on BK DNAemia duration using intervention as a time-dependent covariate. RESULTS: BK-free survival was 69.1% at 1-year and 54.6% at 3-year posttransplant. After multivariate adjustment, BK DNAemia was associated with young age at transplant (aHR, age 5-<12 vs. ≥12 (years): 2.5 (1.4-4.5); p = .001) and steroid-based immunosuppression (IS) (aHR: 2.2 [1.1-4.5]; p = .03). We found no effect of DNAemia on AR (aHR: 1.25; p = .5), PS (aHR: 2.85; p = .22), and GS (aHR: 0.56; p = .41). Of 70 patients with DNAemia, 22 (31.4%) received no treatment, 20 (28.6%) received IS reduction alone, and 28 patients (40%) received treatment with at least one pharmacological agent (leflunomide, IVIG, ciprofloxacin, cidofovir). Sixty-three patients (90%) cleared DNAemia with median time to resolution of 2.4 months (IQR:1.4-5.6). We found no significant effect of BK-directed pharmacological treatment on time to resolution (aHR: 0.64;p = .13). BK-directed agents were well tolerated. CONCLUSIONS: BK DNAemia is associated with a young age at transplant and steroid-based maintenance IS. We found no effect of BK DNAemia on AR, GS, and PS.

Anemia in Pediatric Kidney Transplant Recipients-Etiologies and Management.

Posttransplant anemia (PTA) is a common complication of pediatric kidney transplantation, with a prevalence ranging from 22 to 85%. PTA is categorized as early (within 6 months posttransplant) and late (>6 months posttransplant). Early PTA is typically associated with surgical blood losses and iron deficiency. Late PTA primarily results from graft dysfunction; however, iron deficiency, drug toxicity, and posttransplant inflammation also play a role. PTA is more severe compared with the anemia in glomerular-filtration-rate matched patients with native chronic kidney disease. Treatment of PTA is directed toward the underlying cause. Erythropoiesis stimulating agents (ESA) are effective; however, their use is limited in the transplant setting. Timely diagnosis and treatment of PTA are vital to prevent long-term adverse outcomes in pediatric transplant recipients.

Antineutrophilic cytoplasmic antibody-associated vasculitis and the kidney.

PURPOSE OF REVIEW: The purpose of this review is to highlight recent studies that have emerged on the topic of ANCA-associated vasculitis with some historical context. The review also discusses how the adult data is relevant to pediatric patients. RECENT FINDINGS: Pediatric studies on AAV are lacking. Therapies targeted to the inflammatory cascade specifically implicated in AAV, such as MPO inhibitors and complement mediators, are emerging. The PEXIVAS study recently called into question the routine use of plasma exchange (PLEX) in severe AAV, with no difference in ESKD or mortality found between patients who did or did not receive PLEX. Longer maintenance duration of nearly 48 months is preferred as compared with shorter duration in patients who are not on dialysis because of higher relapse rates in children with AAV. SUMMARY: Current treatment in AAV includes corticosteroids, rituximab, and cyclophosphamide for induction. Maintenance therapy commonly consists of azathioprine or rituximab. Plasma exchange (PLEX) is no longer recommended for induction therapy for AAV but some experts still consider this as an option for patients who are not responding to therapy or have severe disease at presentation. However, emerging novel therapies may be on the horizon.

Steroid avoidance/withdrawal and maintenance immunosuppression in pediatric kidney transplantation.

BACKGROUND: Corticosteroids have been an integral part of maintenance immunosuppression for pediatric kidney transplantation. However, prolonged steroid therapy is associated with significant toxicities resulting in several SW/avoidance strategies in recent years. METHOD/OBJECTIVE: This comprehensive review aims to discuss steroid-related toxicities and the safety, efficacy, and benefit of steroid avoidance/withdrawal immunosuppression in pediatric kidney transplant recipients. RESULTS: Initial studies of SW/avoidance conducted in the setting of CSA and AZA showed an increased incidence of AR but no increase in graft loss or mortality with SW/avoidance maintenance immunosuppression. Studies performed under modern immunosuppression (induction therapy, Tac, and MMF) show no significant increase in AR or graft loss with SW/avoidance immunosuppression. Furthermore, SW/avoidance immunosuppression is associated with significant improvement in growth, BMI, BP control, and lipid profile in pediatric kidney transplant recipients. Despite these data, SW/avoidance remains controversial, and only 40% of pediatric kidney transplant recipients in the United States are currently on SW/avoidance maintenance immunosuppression. CONCLUSION: SW/avoidance maintenance immunosuppression is safe and associated with fewer side effects compared with steroid-inclusive maintenance immunosuppression in pediatric kidney transplant recipients.

Induction and maintenance immunosuppression in pediatric kidney transplantation-Advances and controversies.

Advances in immunosuppression have improved graft survival in pediatric kidney transplant recipients; however, treatment-related toxicities need to be balanced against the possibility of graft rejection. Several immunosuppressive agents are available for use in transplant recipients; however, the optimal combinations of agents remain unclear, resulting in variations in institutional protocols. Lymphocyte-depleting antibodies, specifically ATG, are the most common induction agent used for pediatric kidney transplantation in the US. Basiliximab may be used for induction in immunologically low-risk children; however, pediatric data are scarce. CNIs and antiproliferative agents (mostly Tac and mycophenolate in recent years) constitute the backbone of maintenance immunosuppression. Steroid-avoidance maintenance regimens remain controversial. Belatacept and mTOR inhibitors are used in children under specific circumstances such as non-adherence or CNI toxicity. This article reviews the indications, mechanism of action, efficacy, dosing, and side effect profiles of various immunosuppressive agents available for pediatric kidney transplantation.

Burosumab in X-linked hypophosphatemia and perspective for chronic kidney disease.

PURPOSE OF REVIEW: Perturbations in phosphate and vitamin D homeostasis impacts skeletal health in children and adults. Study of inherited and acquired hypophosphatemic syndromes led to the discovery of fibroblast growth factor 23 (FGF23) as a potent regulator of phosphate and vitamin D metabolism, and advanced our understanding of the pathophysiology of mineral and bone disorder in chronic kidney disease (CKD-MBD). Here, we review a recently approved therapy for patients with X-linked hypophosphatemia (XLH) using a novel anti-FGF23 antibody, burosumab, and discuss the implications of such targeted therapy in CKD. RECENT FINDINGS: In children and adults with XLH, burosumab treatment significantly increased renal tubular phosphate reabsorption and normalized serum phosphorus concentrations. Prolonged treatment with burosumab showed a favorable safety profile, improved healing of rickets in children, and fractures and pseudofractures in adults. FGF23 excess in CKD is independently associated with left ventricular hypertrophy and cardiovascular mortality. Research strategies to lower FGF23 in animal models of CKD are rapidly advancing and a question that remains to be answered is whether FGF23 blockade will offer a new targeted intervention for disordered mineral metabolism in CKD. SUMMARY: Findings from recently concluded clinical trials in adults and children with XLH provide evidence for improved skeletal health with burosumab therapy with normalization of phosphate and vitamin D metabolism. Targeted anti-FGF23 antibody treatment of XLH has emerged as a novel therapeutic strategy to treat an inherited disorder of FGF23 excess.

Fibroblast growth factor 23 and phosphate homeostasis.

PURPOSE OF REVIEW: The current review highlights recent advances in the area of renal tubular phosphate transport and its regulation by fibroblast growth factor 23 (FGF23), a potent regulator of phosphate homeostasis. RECENT FINDINGS: Recent studies demonstrate that FGF23 binds to both membrane and soluble form of α-klotho to activate FGF receptor signaling pathways. Parathyroid hormone and FGF23 equivalently decrease sodium-dependent phosphate cotransport but the effect is not additive, suggesting a shared but not synergistic mechanism of action. Crosstalk occurs downstream of parathyroid hormone-receptor and FGF23-receptor signaling and converge at the level of the scaffolding protein, sodium-hydrogen exchanger regulatory factor-1. A novel mechanism for phosphate efflux through the basolateral membrane of renal proximal tubular epithelia via an atypical G-protein coupled receptor, Xenotropic and polytropic retrovirus receptor 1 (XPR1), was recently identified. Conditional deletion of Xpr1 gene in renal proximal tubules in mice leads to hypophosphatemic rickets and Fanconi syndrome establishing an important role for XPR1 in phosphate homeostasis. A novel anti-FGF23 antibody, burosumab, was recently approved to treat X-linked hypophosphatemia, a human disorder of FGF23 excess. SUMMARY: Significant advances in understanding the cellular and molecular aspects of renal tubular phosphate transport and its regulation by FGF23 has led to the discovery of novel therapeutics to treat human disorders of phosphate homeostasis.