Faculty Bibliography

INTRODUCTION/UNASSIGNED:The prognostic value of the discrepancy between the estimated glomerular filtration rate (eGFR) using cystatin C (eGFRcys) and creatinine (eGFRcr) in recently hospitalized adults remains poorly understood. METHODS/UNASSIGNED:We characterized the difference between eGFRcys and eGFRcr, at 3 months after discharge, in 1534 hospitalized adults; 767 (50%) with acute kidney injury (AKI) matched 1:1 with patients who did not develop AKI. We used survival analysis to determine the associations between having lower eGFRcys than eGFRcr with risk of end-stage kidney disease (ESKD), major atherosclerotic cardiac events (MACE), heart failure hospitalization, and death after a a median follow-up of 4.7 years. RESULTS/UNASSIGNED:for interaction with AKI all > 0.1). CONCLUSION/UNASSIGNED:Our findings suggest that the eGFRcys-eGFRcr discrepancy may serve as a valuable prognostic marker in recently hospitalized patients, informing risk stratification and potential interventions.

RATIONALE & OBJECTIVE/OBJECTIVE:Despite national efforts, the uptake of home dialysis (peritoneal dialysis or home hemodialysis) remains low. Characteristics of the built environment may differentially impact home dialysis use. STUDY DESIGN/METHODS:Retrospective cohort study (2010-2019). SETTING & PARTICIPANTS/METHODS:1,103,695 adults (aged≥18 years) initiating dialysis in the US Renal Data System. EXPOSURE/METHODS:We examined 3 built environment domains based on residential ZIP code: (1) medically underserved areas (MUAs), defined as neighborhoods with limited primary care access; (2) distance to the nearest dialysis facility; and (3) distribution of housing characteristics (structure and overcrowding). OUTCOME/RESULTS:Uptake of home dialysis modalities at dialysis initiation. ANALYTICAL APPROACH/METHODS:We quantified associations between built environment characteristics and home dialysis initiation using multilevel logistic regression stratified by urbanicity type (urban, suburban, small-town, and rural). RESULTS:Among adults initiating dialysis, 40.8% lived in MUAs. Across ZIP codes, the mean percentage of overcrowded housing was 4.2% (SD, 4.7%), and the percentage of detached housing was 61.1% (SD, 21.1%); mean distance to the nearest dialysis facility was 5.5km (SD, 9.1km). Living in MUAs was associated with reduced home dialysis use only in urban (OR, 0.94; 95% CI, 0.91-0.96) and suburban (OR, 0.92; 95% CI, 0.89-0.94) areas. Similarly, housing overcrowding was associated with decreased home dialysis use only in urban (OR, 0.88; 95% CI, 0.86-0.89) and suburban (OR, 0.91; 95% CI, 0.90-0.93) areas. Longer distance to a dialysis facility was the most salient neighborhood factor associated with increased home dialysis use in small towns (OR, 1.14; 95% CI, 1.12-1.16) and rural areas (OR, 1.17; 95% CI, 1.15-1.19). LIMITATIONS/CONCLUSIONS:Housing characteristics were measured at the ZIP code level. CONCLUSIONS:Built environment characteristics associated with home dialysis uptake vary by urbanicity. Policies should address built environment barriers that are specific to urbanicity level. For example, increasing the frequency of dialysate delivery schedules could address housing space constraints in urban and suburban areas, and promoting home dialysis might be more effective for patients living far from dialysis centers in small-town and rural areas.

OBJECTIVES/UNASSIGNED:To review the different analgesic modalities and benefits of non-opioid pain management options as well as their evidence-based, established superiority, compared to opioid medications. MATERIALS/UNASSIGNED:We review the updated literature about pain management of renal colic, a prevalent and painful urologic condition. Prescribers must know the efficacy, safety and possible ramifications of analgesic selections. RESULTS/UNASSIGNED:Commonly prescribed medications in the United States (US) include non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and opioids. In the context of the current epidemic of death from overdoses of opioids in the US, the frequency of opioid prescribing for renal colic is likely excessive, problematic and potentially remediable. We also present analgesic modalities revolving around interventions with peri-procedural pain management for ureteroscopy and percutaneous nephrolithotomy. After touching on the implications of misguided opioid use, especially in the context of kidney stone disease, and despite the evidence and consensus guidelines supporting NSAIDs in renal colic, current evidence has shown that many clinicians continue to prescribe opioids as first-line treatment. Finally, we highlight current efforts targeted at the reduction of opioid use and prescription in the setting of provider education and decision aids in curbing misguided opioid use in renal colic. CONCLUSIONS/UNASSIGNED:While the evidence against treating kidney stones with opioids is clear, more work is needed to shift current practices to reflect that renal colic is a non-opioid-requiring condition.

BACKGROUND:), can be self- or caregiver-administered at home with fixed-dosing for patients ≥ 12 years of age. This real-world study aimed to understand treatment preferences among individuals with PH1, highlighting challenges in administration of current treatments. METHODS:A cross-sectional web-based survey was conducted among U.S.-based adults (aged ≥ 18) diagnosed with PH1. The survey consisted of a 20-25 min questionnaire and was conducted from October to December 2023. RESULTS:The study participants (N = 39) included both male (N = 26) and female (N = 13) adults with PH1. Participants came from a range of community settings, including urban (46%), rural (39%), and suburban (15%); and were full- or part-time workers (56%) or students (41%). Most participants were on lumasiran therapy (95%) for an average of 1 year (range: 0.3-1.8 years). The survey revealed that the commonly reported factors important for treatment selection among participants living with PH1 were frequency of administration, treatment administrator, time required for treatment, and place of administration. The ability to self-administer was ranked as the top choice by most participants. Over half (56%) found quarterly injections easy or very easy. Similarly, 56-59% found home administration, whether self- or healthcare provider (HCP)-administered, easy or very easy. Nearly half (46%) considered injections at medical facilities challenging or very challenging. The majority indicated traveling > 15 min for injections would be burdensome (57%) and arranging appointments problematic (54%). When comparing administration methods, 72% preferred self-injection over HCP-administered injections. Regarding treatment regimens, 57% found it easy or very easy to receive monthly injections initially, before switching to quarterly. Additionally, 64% preferred a medication dosage that is not weight-based. While participants expressed a preference for less frequent treatments, 67% preferred self-injection at home over medical facility injections, and 67% preferred monthly injections at home over quarterly injections at a medical facility. CONCLUSIONS:This study shows that patients with PH1 value treatments that are convenient and fit their lifestyle.

IMPORTANCE/UNASSIGNED:Hyperkalemia is a common complication of taking a renin-angiotensin-aldosterone system inhibitor (RAASi). Post hoc analyses of large randomized clinical trials suggested that the addition of sodium-glucose cotransporter 2 inhibitors (SGLT2i) may attenuate this risk. It is unknown if this observation extends to daily clinical practice. OBJECTIVE/UNASSIGNED:To evaluate the association between SGLT2i initiation and hyperkalemia in individuals receiving RAASi with a background of diabetes, heart failure, or chronic kidney disease. DESIGN, SETTING, AND PARTICIPANTS/UNASSIGNED:This population-based retrospective cohort study was conducted in Ontario, Canada, from July 1, 2015, to June 30, 2021. The cohort comprised adults 66 years and older who were prescribed a RAASi and had a history of diabetes or heart failure, an estimated glomerular filtration rate of less than 45 mL/min/1.73 m2, and/or a urine albumin to creatinine ratio of greater than 30 mg/mmol. The data were analyzed between March 28, 2023, and March 22, 2024. EXPOSURE/UNASSIGNED:The study exposure was a new prescription of an SGLT2i compared to noninitiation of an SGLT2i. Inverse probability of treatment weighting by a propensity score for the receipt of SGLT2i was used to achieve balance of baseline covariates in both exposure groups. MAIN OUTCOMES AND MEASURES/UNASSIGNED:The primary study outcome was hyperkalemia, defined as a serum potassium of greater than 5.5 mEq/L or an administrative code for an inpatient or outpatient encounter with hyperkalemia within 1 year of the index date. RESULTS/UNASSIGNED:A total of 20 063 individuals who initiated an SGLT2i (mean [SD] age, 76.9 [6.6] years; 12 020 [59.9%] male) were compared to a pseudopopulation of 19 781 nonusers (mean [SD] age, 76.8 [7.0] years; 11 731 [59.3%] male). In the overall cohort, 95% had diabetes, 17% had heart failure, and 32% had stage 3 to 5 chronic kidney disease. SGLT2i initiation was associated with a lower risk of hyperkalemia (hazard ratio, 0.89 [95% CI, 0.82-0.96]). SGLT2i users had a significantly lower rate of RAASi discontinuation compared to nonusers (36% vs 45%; P < .001). CONCLUSIONS AND RELEVANCE/UNASSIGNED:This cohort study demonstrated that, among individuals with diabetes, heart failure, or chronic kidney disease who were receiving a RAASi, SGLT2i initiation was associated with a lower risk of hyperkalemia and RAASi discontinuation.

The scarcity of transplantable organs represents a worldwide public health crisis, and as a result, thousands of people with end-stage kidney disease (ESKD) die waiting for a transplant each year. Xenotransplantation involves transplanting organs from an animal source into humans, offering a potential solution to this significant unmet need. Indeed, if there is a limitless supply of organs, many more patients who do not meet the current criteria for transplant eligibility could also be considered candidates. While there are examples of attempts to transplant animal tissues or organs into humans dating back over 300 years, none were successful due to cross-species immunologic incompatibility. Even so, significant advances in genetic engineering and the emergence of novel immunosuppressive agents have spurred impressive improvements in xenograft survival in preclinical studies involving nonhuman primates. Furthermore, recent reports of genetically modified pig kidney and heart xenotransplants in human decedents and living recipients on a compassionate use basis have provided impetus to advancing the field towards first-in-human trials. However, studies in nonhuman primates and humans thus far have described adaptive as well as innate immune-mediated xenograft injury. Understanding the mechanistic aspects of these responses at the cellular and molecular levels is critical to the development of targeted genetic modifications and innovative therapeutic strategies aimed at preventing rejection and inducing tolerance. Moreover, the physiological components of the bidirectional communication between the human host and pig xenograft must also be understood and manipulated. Here, we review the breakthroughs in renal xenotransplantation in the past few decades and highlight the immunologic hurdles that have yet to be overcome.

Enteric hyperoxaluria, a risk factor for kidney stone disease, often arises from malabsorptive bariatric surgeries or inflammatory bowel diseases. Current murine models for studying this condition are limited, necessitating new approaches. This study aims to establish two novel and distinct mouse models to investigate enteric hyperoxaluria: one simulating Roux-en-Y gastric bypass surgery and the other Crohn's ileitis. In the first model, diet-induced obese C57BL/6J male mice underwent either sham or bypass surgery, followed by three weeks on a high-fat, oxalate-enriched diet. In the second model, SAMP1/YitFc and AKR mice were gradually introduced to high-fat diets, later supplemented with oxalate while reducing fat content. Samples of urine, blood, and feces were collected to assess oxalate, creatinine, and fecal lipid profiles. Results showed hyperoxaluria and increased stool fat content, indicating fat malabsorption, in both SAMP1 and bypass mice compared to controls. Kidney injury was also observed. These findings confirm the successful establishment of enteric hyperoxaluria in both models, highlighting the role of dietary oxalate, intestinal inflammation, and fat malabsorption in disease progression. These models provide valuable tools for exploring cellular and molecular mechanisms in enteric hyperoxaluria and may inform future therapeutic strategies.

PURPOSE/UNASSIGNED:Urine calcium excretion is greater after dinner and urine volumes are lower. The result is higher urine calcium concentrations, which may confer greater risk of stone formation, at night. We considered whether night-time administration - as compared with daytime administration - of thiazides would be more effective for stone prevention. MATERIALS AND METHODS/UNASSIGNED:We performed 12-hour urine collections in 7 patients taking 25 mg of chlorthalidone (CTD) and 10 patients taking 25 mg of hydrochlorothiazide (HCTZ). Participants completed urine collections at baseline, again after a week of morning medication administration, and again after a week of evening administration, all on repeated self-selected diets. RESULTS/UNASSIGNED:Chlorthalidone reduced urine calcium excretion for both 12-hour periods whether administered in the morning or in the evening: morning dosing lowered urine calcium from 130±70 mg/gram Cr at baseline, to 76±52 mg/gram Cr (P<0.02); evening dosing lowered it to 87±51 mg/gram Cr, which was not significant. On the other hand, HCTZ did not reduce urine calcium excretion regardless of the time of administration: mean 24-hour urine calcium excretion (UCa) was 124±38 mg/gram Cr at baseline and 106±40 mg/gram Cr when HCTZ was given in AM, and 117±54 mg/gram Cr when given in PM. CONCLUSION/UNASSIGNED:We conclude that the long-acting and more effective CTD is a preferable agent for stone prevention. Time of administration does not appear to be important, although morning administration may more effectively address higher post-dinner calcium excretion. The most commonly used thiazide (HCTZ) is shorter acting, frequently dosed once per day, but does not appear to reduce urine calcium excretion at this dose.