Spatiotemporal multilevel joint modeling of longitudinal and survival outcomes in end-stage kidney disease.

Individuals with end-stage kidney disease (ESKD) on dialysis experience high mortality and excessive burden of hospitalizations over time relative to comparable Medicare patient cohorts without kidney failure. A key interest in this population is to understand the time-dynamic effects of multilevel risk factors that contribute to the correlated outcomes of longitudinal hospitalization and mortality. For this we utilize multilevel data from the United States Renal Data System (USRDS), a national database that includes nearly all patients with ESKD, where repeated measurements/hospitalizations over time are nested in patients and patients are nested within (health service) regions across the contiguous U.S. We develop a novel spatiotemporal multilevel joint model (STM-JM) that accounts for the aforementioned hierarchical structure of the data while considering the spatiotemporal variations in both outcomes across regions. The proposed STM-JM includes time-varying effects of multilevel (patient- and region-level) risk factors on hospitalization trajectories and mortality and incorporates spatial correlations across the spatial regions via a multivariate conditional autoregressive correlation structure. Efficient estimation and inference are performed via a Bayesian framework, where multilevel varying coefficient functions are targeted via thin-plate splines. The finite sample performance of the proposed method is assessed through simulation studies. An application of the proposed method to the USRDS data highlights significant time-varying effects of patient- and region-level risk factors on hospitalization and mortality and identifies specific time periods on dialysis and spatial locations across the U.S. with elevated hospitalization and mortality risks.

Accuracy of Continuous Glucose Monitoring in Hemodialysis Patients With Diabetes.

OBJECTIVE: In the general population, continuous glucose monitoring (CGM) provides convenient and less-invasive glucose measurements than conventional self-monitored blood glucose and results in reduced hypoglycemia and hyperglycemia and increased time in target glucose range. However, accuracy of CGM versus blood glucose is not well established in hemodialysis patients. RESEARCH DESIGN AND METHODS: Among 31 maintenance hemodialysis patients with diabetes hospitalized from October 2020 to May 2021, we conducted protocolized glucose measurements using Dexcom G6 CGM versus blood glucose, with the latter measured before each meal and at night, plus every 30-min during hemodialysis. We examined CGM-blood glucose correlations and agreement between CGM versus blood glucose using Bland-Altman plots, percentage of agreement, mean and median absolute relative differences (ARDs), and consensus error grids. RESULTS: Pearson and Spearman correlations for averaged CGM versus blood glucose levels were 0.84 and 0.79, respectively; Bland-Altman showed the mean difference between CGM and blood glucose was ∼+15 mg/dL. Agreement rates using %20/20 criteria were 48.7%, 47.2%, and 50.2% during the overall, hemodialysis, and nonhemodialysis periods, respectively. Mean ARD (MARD) was ∼20% across all time periods; median ARD was 19.4% during the overall period and was slightly lower during nonhemodialysis (18.2%) versus hemodialysis periods (22.0%). Consensus error grids showed nearly all CGM values were in clinically acceptable zones A (no harm) and B (unlikely to cause significant harm). CONCLUSIONS: In hemodialysis patients with diabetes, although MARD values were higher than traditional optimal analytic performance thresholds, error grids showed nearly all CGM values were in clinically acceptable zones. Further studies are needed to determine whether CGM improves outcomes in hemodialysis patients.

A single-center, assessor-blinded, randomized controlled clinical trial to test the safety and efficacy of a novel brain-computer interface controlled functional electrical stimulation (BCI-FES) intervention for gait rehabilitation in the chronic stroke population.

BACKGROUND: In the United States, there are over seven million stroke survivors, with many facing gait impairments due to foot drop. This restricts their community ambulation and hinders functional independence, leading to several long-term health complications. Despite the best available physical therapy, gait function is incompletely recovered, and this occurs mainly during the acute phase post-stroke. Therapeutic options are limited currently. Novel therapies based on neurobiological principles have the potential to lead to long-term functional improvements. The Brain-Computer Interface (BCI) controlled Functional Electrical Stimulation (FES) system is one such strategy. It is based on Hebbian principles and has shown promise in early feasibility studies. The current study describes the BCI-FES clinical trial, which examines the safety and efficacy of this system, compared to conventional physical therapy (PT), to improve gait velocity for those with chronic gait impairment post-stroke. The trial also aims to find other secondary factors that may impact or accompany these improvements and establish the potential of Hebbian-based rehabilitation therapies. METHODS: This Phase II clinical trial is a two-arm, randomized, controlled, longitudinal study with 66 stroke participants in the chronic (> 6 months) stage of gait impairment. The participants undergo either BCI-FES paired with PT or dose-matched PT sessions (three times weekly for four weeks). The primary outcome is gait velocity (10-meter walk test), and secondary outcomes include gait endurance, range of motion, strength, sensation, quality of life, and neurophysiological biomarkers. These measures are acquired longitudinally. DISCUSSION: BCI-FES holds promise for gait velocity improvements in stroke patients. This clinical trial will evaluate the safety and efficacy of BCI-FES therapy when compared to dose-matched conventional therapy. The success of this trial will inform the potential utility of a Phase III efficacy trial. TRIAL REGISTRATION: The trial was registered as "BCI-FES Therapy for Stroke Rehabilitation" on February 19, 2020, at clinicaltrials.gov with the identifier NCT04279067.

Variability in Standardized Mortality Rates Among Pediatric Traumatic Brain Injury Patients: A Comparative Analysis of Trauma Centers.

INTRODUCTION: Traumatic brain injury (TBI) causes significant morbidity and mortality in pediatric patients and care is highly variable. Standardized mortality ratio (SMR) summarizes the mortality rate of a specific center relative to the expected rates across all centers, adjusted for case-mix. This study aimed to evaluate variations in SMRs among pediatric trauma centers for TBI. METHODS: Patients aged 1-18 diagnosed with TBI within the National Trauma Data Bank (NTDB) from 2017 to 2019 were included. Center-specific SMRs and 95% confidence intervals identified centers with mortality rates significantly better or worse than the median SMR for all centers. RESULTS: 316 centers with 10,598 patients were included. SMRs were risk-adjusted for patient risk factors. Unadjusted mortality ranged from 16.5 to 29.5%. Three centers (1.5%) had significantly better SMR (SMR <1) and three centers (1.5%) had significantly worse SMR (SMR >1). Significantly better centers had a lower proportion of neurosurgical intervention (2.4% vs. 11.8%, p < 0.001), a higher proportion of supplemental oxygen administration (93.7% vs. 83.5%, p = 0.004) and venous thromboembolism prophylaxis (53.2% vs. 40.6%, p < 0.001) compared to significantly worse centers. CONCLUSIONS: This study identified centers that have significantly higher and lower mortality rates for pediatric TBI patients relative to the overall median rate. These data provide a benchmark for pediatric TBI outcomes and institutional quality improvement. LEVEL OF EVIDENCE: Level III. TYPE OF STUDY: Retrospective Comparative Study.

Impact of Thyroid Status on Incident Kidney Dysfunction and Chronic Kidney Disease Progression in a Nationally Representative Cohort.

OBJECTIVE: To examine the relationship between thyroid status and incident kidney dysfunction/chronic kidney disease (CKD) progression. PATIENTS AND METHODS: We examined incident thyroid status, ascertained by serum thyrotropin (TSH) levels measured from January 1, 2007, through December 31, 2018, among 4,152,830 patients from the Optum Labs Data Warehouse, containing deidentified retrospective administrative claims data from a large national health insurance plan and electronic health record data from a nationwide network of provider groups. Associations of thyroid status, categorized as hypothyroidism, euthyroidism, or hyperthyroidism (TSH levels >5.0, 0.5-5.0, and <0.5 mIU/L, respectively), with the composite end point of incident kidney dysfunction in patients without baseline kidney dysfunction and CKD progression in those with baseline CKD were examined using Cox models. RESULTS: Patients with hypothyroidism and hyperthyroidism had higher risk of incident kidney dysfunction/CKD progression in expanded case-mix analyses (reference: euthyroidism): adjusted hazard ratios (aHRs) (95% CIs) were 1.37 (1.34 to 1.40) and 1.42 (1.39 to 1.45), respectively. Incrementally higher TSH levels in the upper reference range and TSH ranges for subclinical, mild overt, and overt hypothyroidism (≥3.0-5.0, >5.0-10.0, >10.0-20.0, and >20.0 mIU/L, respectively) were associated with increasingly higher risk of the composite end point (reference: TSH level, 0.5 to <3.0 mIU/L): aHRs (95% CIs) were 1.10 (1.09 to 1.11), 1.37 (1.34 to 1.40), 1.70 (1.59 to 1.83), and 1.70 (1.50 to 1.93), respectively. Incrementally lower TSH levels in the subclinical (<0.5 mIU/L) and overt (<0.1 mIU/L) hyperthyroid ranges were also associated with the composite end point: aHRs (95% CIs) were 1.44 (1.41 to 1.47) and 1.48 (1.39 to 1.59), respectively. CONCLUSION: In a national cohort, TSH levels in the upper reference range or higher (≥3.0 mIU/L) and below the reference range (<0.5 mIU/L) were associated with incident kidney dysfunction/CKD progression.

Multivariate spatiotemporal functional principal component analysis for modeling hospitalization and mortality rates in the dialysis population.

Dialysis patients experience frequent hospitalizations and a higher mortality rate compared to other Medicare populations, in whom hospitalizations are a major contributor to morbidity, mortality, and healthcare costs. Patients also typically remain on dialysis for the duration of their lives or until kidney transplantation. Hence, there is growing interest in studying the spatiotemporal trends in the correlated outcomes of hospitalization and mortality among dialysis patients as a function of time starting from transition to dialysis across the United States Utilizing national data from the United States Renal Data System (USRDS), we propose a novel multivariate spatiotemporal functional principal component analysis model to study the joint spatiotemporal patterns of hospitalization and mortality rates among dialysis patients. The proposal is based on a multivariate Karhunen-Loéve expansion that describes leading directions of variation across time and induces spatial correlations among region-specific scores. An efficient estimation procedure is proposed using only univariate principal components decompositions and a Markov Chain Monte Carlo framework for targeting the spatial correlations. The finite sample performance of the proposed method is studied through simulations. Novel applications to the USRDS data highlight hot spots across the United States with higher hospitalization and/or mortality rates and time periods of elevated risk.

Center Volume and Survival Relationship for Neonates With Congenital Diaphragmatic Hernia Treated With Extracorporeal Life Support.

OBJECTIVES: Literature is emerging regarding the role of center volume as an independent variable contributing to improved outcomes. A higher volume of index procedures may be associated with decreased morbidity and mortality. This association has not been examined for the subgroup of infants with congenital diaphragmatic hernia (CDH) receiving extracorporeal life support (ECLS). Our study aims to examine the risk-adjusted association between center volume and outcomes in CDH-ECLS neonates, hypothesizing that higher center volume confers a survival advantage. DESIGN: Multicenter, retrospective comparative study using the Extracorporeal Life Support Organization database. SETTING: One hundred twenty international pediatric centers. PATIENTS: Neonates with CDH managed with ECLS from 2000 to 2019. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The cohort included 4,985 neonates with a mortality rate of 50.6%. For the 120 centers studied, mean center volume was 42.4 ± 34.6 CDH ECLS cases over the 20-year study period. In an adjusted model, higher ECLS volume was associated with lower odds of mortality: odds ratio (OR) 0.995 (95% CI, 0.992-0.999; p = 0.014). For an increase in one sd in volume, that is, 1.75 cases annually, the OR for mortality was lower by 16.7%. Volume was examined as a categorical exposure variable where low-volume centers (fewer than 2 cases/yr) were associated with 54% higher odds of mortality (OR, 1.54; 95% CI, 1.03-2.29) compared with high-volume centers. On-ECLS complications (mechanical, neurologic, cardiac, hematologic metabolic, and renal) were not associated with volume. The likelihood of infectious complications was higher for low- (OR, 1.90; 95% CI, 1.06-3.40) and medium-volume (OR, 1.87; 95% CI, 1.03-3.39) compared with high-volume centers. CONCLUSIONS: In this study, a survival advantage directly proportional to center volume was observed for CDH patients managed with ECLS. There was no significant difference in most complication rates. Future studies should aim to identify factors contributing to the higher mortality and morbidity observed at low-volume centers.

Development and Validation of a Prediction Model for Incident Hypothyroidism in a National Chronic Kidney Disease Cohort.

CONTEXT: Hypothyroidism is a common yet under-recognized condition in patients with chronic kidney disease (CKD), which may lead to end-organ complications if left untreated. OBJECTIVE: We developed a prediction tool to identify CKD patients at risk for incident hypothyroidism. METHODS: Among 15 642 patients with stages 4 to 5 CKD without evidence of pre-existing thyroid disease, we developed and validated a risk prediction tool for the development of incident hypothyroidism (defined as thyrotropin [TSH] > 5.0 mIU/L) using the Optum Labs Data Warehouse, which contains de-identified administrative claims, including medical and pharmacy claims and enrollment records for commercial and Medicare Advantage enrollees as well as electronic health record data. Patients were divided into a two-thirds development set and a one-third validation set. Prediction models were developed using Cox models to estimate probability of incident hypothyroidism. RESULTS: There were 1650 (11%) cases of incident hypothyroidism during a median follow-up of 3.4 years. Characteristics associated with hypothyroidism included older age, White race, higher body mass index, low serum albumin, higher baseline TSH, hypertension, congestive heart failure, exposure to iodinated contrast via angiogram or computed tomography scan, and amiodarone use. Model discrimination was good with similar C-statistics in the development and validation datasets: 0.77 (95% CI 0.75-0.78) and 0.76 (95% CI 0.74-0.78), respectively. Model goodness-of-fit tests showed adequate fit in the overall cohort (P = .47) as well as in a subcohort of patients with stage 5 CKD (P = .33). CONCLUSION: In a national cohort of CKD patients, we developed a clinical prediction tool identifying those at risk for incident hypothyroidism to inform prioritized screening, monitoring, and treatment in this population.

Inhaled Nitric Oxide Utilization in Congenital Diaphragmatic Hernia Treated With Extracorporeal Life Support: A Propensity Score Analysis.

Although used commonly, ability of inhaled nitric oxide (iNO) to improve outcomes in infants with congenital diaphragmatic hernia (CDH) who receive extracorporeal life support (ECLS) remains controversial. We sought to determine the association between pre-ECLS use of iNO and mortality in infants with CDH from the Extracorporeal Life Support Organization (ELSO) Registry. Neonates who underwent ECLS for CDH were identified from the ELSO Registry from 2009 to 2019. Patients were categorized into those treated with iNO versus not prior to initiating ECLS. Patients were then matched 1:1 for case-mix based on pre-ECLS covariates using the propensity score (PS) for iNO treatment. The matched groups were compared for mortality. The matched cohorts were also compared for ELSO-defined systems-based complications as secondary outcomes. There were a total of 3,041 infants with an overall mortality of 52.2% and a pre-ECLS iNO use rate of 84.8%. With 1:1 matching, there were 461 infants with iNO use and 461 without iNO use. Following matching, use of iNO was not associated with a difference in mortality (odds ratio [OR] = 0.805; 95% confidence interval [CI], 0.621-1.042; p = 0.114). Results were similar in unadjusted analyses, and after controlling for covariates in the full cohort of patients and in the 1:1 matched data. Patients receiving iNO had significantly higher odds of renal complications (OR = 1.516; 95% CI, 1.141-2.014; p = 0.004), but no other significant differences were observed among secondary outcomes. ECLS use of iNO in CDH patients was not associated with a difference in mortality. Future randomized controlled studies are needed to delineate the utility of iNO in CDH patients.

High-Dimensional Fixed Effects Profiling Models and Applications in End-Stage Kidney Disease Patients: Current State and Future Directions.

Profiling analysis aims to evaluate health care providers, including hospitals, nursing homes, or dialysis facilities among others with respect to a patient outcome, such as 30-day unplanned hospital readmission or mortality. Fixed effects (FE) profiling models have been developed over the last decade, motivated by the overall need to (a) improve accurate identification or "flagging" of under-performing providers, (b) relax assumptions inherent in random effects (RE) profiling models, and (c) take into consideration the unique disease characteristics and care/treatment processes of end-stage kidney disease (ESKD) patients on dialysis. In this paper, we review the current state of FE methodologies and their rationale in the ESKD population and illustrate applications in four key areas: profiling dialysis facilities for (1) patient hospitalizations over time (longitudinally) using standardized dynamic readmission ratio (SDRR), (2) identification of dialysis facility characteristics (e.g., staffing level) that contribute to hospital readmission, and (3) adverse recurrent events using standardized event ratio (SER). Also, we examine the operating characteristics with a focus on FE profiling models. Throughout these areas of applications to the ESKD population, we identify challenges for future research in both methodology and clinical studies.

Dysnatremia and risk of bloodstream infection in dialysis patients.

Background: Emerging data suggest that sodium disarrays including hyponatremia are potential risk factors for infection ensuing from impairments in host immunity, which may be exacerbated by coexisting conditions (i.e. mucosal membrane and cellular edema leading to breakdown of microbial barrier function). While dysnatremia and infection-related mortality are common in dialysis patients, little is known about the association between serum sodium levels and the risk of bloodstream infection in this population. Methods: Among 823 dialysis patients from the national Biospecimen Registry Grant Program who underwent serum sodium testing over the period January 2008-December 2014, we examined the relationship between baseline serum sodium levels and subsequent rate of bloodstream infection. Bloodstream infection events were directly ascertained using laboratory blood culture data. Associations between serum sodium level and the incidence of bloodstream infection were estimated using expanded case mix-adjusted Poisson regression models. Results: In the overall cohort, ∼10% of all patients experienced one or more bloodstream infection events during the follow-up period. Patients with both lower sodium levels <134 mEq/l and higher sodium levels ≥140 mEq/l had higher incident rate ratios (IRRs) of bloodstream infection in expanded case mix analyses (reference 136-<138 mEq/l), with adjusted IRRs of 2.30 [95% confidence interval (CI) 1.19-4.44], 0.77 (95% CI 0.32-1.84), 1.39 (95% CI 0.78-2.47), 1.88 (95% CI 1.08-3.28) and 1.96 (95% CI 1.08-3.55) for sodium levels <134, 134-<136, 138-<140, 140-<142 and ≥142 Eq/l, respectively. Conclusions: Both lower and higher baseline serum sodium levels were associated with a higher rate of subsequent bloodstream infections in dialysis patients. Further studies are needed to determine whether correction of dysnatremia ameliorates infection risk in this population.

A Bayesian multilevel time-varying framework for joint modeling of hospitalization and survival in patients on dialysis.

Over 782 000 individuals in the United States have end-stage kidney disease with about 72% of patients on dialysis, a life-sustaining treatment. Dialysis patients experience high mortality and frequent hospitalizations, at about twice per year. These poor outcomes are exacerbated at key time periods, such as the fragile period after transition to dialysis. In order to study the time-varying effects of modifiable patient and dialysis facility risk factors on hospitalization and mortality, we propose a novel Bayesian multilevel time-varying joint model. Efficient estimation and inference is achieved within the Bayesian framework using Markov chain Monte Carlo, where multilevel (patient- and dialysis facility-level) varying coefficient functions are targeted via Bayesian P-splines. Applications to the United States Renal Data System, a national database which contains data on nearly all patients on dialysis in the United States, highlight significant time-varying effects of patient- and facility-level risk factors on hospitalization risk and mortality. Finite sample performance of the proposed methodology is studied through simulations.

A phase II, multicenter, open-label, randomized trial of pegfilgrastim for patients with alcohol-associated hepatitis.

Background: In trials conducted in India, recombinant granulocyte colony stimulating factor (GCSF) improved survival in alcohol-associated hepatitis (AH). The aim of this trial was to determine the safety and efficacy of pegfilgrastim, a long-acting recombinant GCSF, in patients with AH in the United States. Methods: This prospective, randomized, open label trial conducted between March 2017 and March 2020 randomized patients with a clinical diagnosis of AH and a Maddrey discriminant function score ≥32 to standard of care (SOC) or SOC+pegfilgrastim (0.6 mg subcutaneously) on Day 1 and Day 8 (clinicaltrials.gov NCT02776059). SOC was 28 days of either pentoxifylline or prednisolone, as determined by the patient's primary physician. The second injection of pegfilgrastim was not administered if the white blood cell count exceeded 30,000/mm3 on Day 8. Primary outcome was survival at Day 90. Secondary outcomes included the incidence of acute kidney injury (AKI), hepatorenal syndrome (HRS), hepatic encephalopathy, or infections. Findings: The study was terminated early due to COVID19 pandemic. Eighteen patients were randomized to SOC and 16 to SOC+pegfilgrastim. All patients received prednisolone as SOC. Nine patients failed to receive a second dose of pegfilgrastin due to WBC > 30,000/mm3 on Day 8. Survival at 90 days was similar in both groups (SOC: 0.83 [95% confidence interval [CI]: 0.57-0.94] vs. pegfilgrastim: 0.73 [95% CI: 0.44-0.89]; p > 0.05; CI for difference: -0.18-0.38). The incidences of AKI, HRS, hepatic encephalopathy, and infections were similar in both treatment arms and there were no serious adverse events attributed to pegfilgrastim. Interpretation: This phase II trial found no survival benefit at 90 days among subjects with AH who received pegfilgrastim+prednisolone compared with subjects receiving prednisolone alone. Funding: was provided by the United States National Institutes of Health and National Institute on Alcohol Abuse and Alcoholism U01-AA021886 and U01-AA021884.

Dietary potassium intake, kidney function, and survival in a nationally representative cohort.

BACKGROUND: In healthy adults, higher dietary potassium intake is recommended given that potassium-rich foods are major sources of micronutrients, antioxidants, and fiber. Yet among patients with advanced kidney dysfunction, guidelines recommend dietary potassium restriction given concerns about hyperkalemia leading to malignant arrhythmias and mortality. OBJECTIVES: Given sparse data informing these recommendations, we examined associations of dietary potassium intake with mortality in a nationally representative cohort of adults from the NHANES. METHODS: We examined associations between daily dietary potassium intake scaled to energy intake (mg/1000 kcal), ascertained by 24-h dietary recall, and all-cause mortality among 37,893 continuous NHANES (1999-2014) participants stratified according to impaired and normal kidney function (estimated glomerular filtration rates <60 and ≥60 mL · min-1 · 1.73 m-2, respectively) using multivariable Cox models. We also examined the impact of the interplay between dietary potassium, source of potassium intake (animal- compared with plant-based sources), and coexisting macronutrient and mineral consumption upon mortality. RESULTS: Among participants with impaired and normal kidney function, the lowest tertile of dietary potassium scaled to energy intake was associated with higher mortality (ref: highest tertile) [adjusted HR (aHR): 1.18; 95% CI: 1.02, 1.38 and aHR: 1.17; 95% CI: 1.06, 1.28, respectively]. Compared with high potassium intake from plant-dominant sources, participants with low potassium intake from animal-dominant sources had higher mortality irrespective of kidney function. Among participants with impaired kidney function, pairings of low potassium intake with high protein, low fiber, or high phosphorus consumption were each associated with higher death risk. CONCLUSIONS: Lower dietary potassium scaled to energy intake was associated with higher mortality, irrespective of kidney function. There was also a synergistic relation of higher potassium intake, plant-based sources, and macronutrient/mineral consumption with survival. Further studies are needed to elucidate pathways linking potassium intake and coexisting dietary factors with survival in populations with and without chronic kidney disease.

The Interplay between Dietary Phosphorous, Protein Intake, and Mortality in a Prospective Hemodialysis Cohort.

(1) Background: Current dietary recommendations for dialysis patients suggest that high phosphorus diets may be associated with adverse outcomes such as hyperphosphatemia and death. However, there has been concern that excess dietary phosphorus restriction may occur at the expense of adequate dietary protein intake in this population. We hypothesized that higher dietary phosphorus intake is associated with higher mortality risk among a diverse cohort of hemodialysis patients. (2) Methods: Among 415 patients from the multi-center prospective Malnutrition, Diet, and Racial Disparities in Kidney Disease Study, we examined the associations of absolute dietary phosphorus intake (mg/day), ascertained by food frequency questionnaires, with all-cause mortality using multivariable Cox models. In the secondary analyses, we also examined the relationship between dietary phosphorus scaled to 1000 kcal of energy intake (mg/kcal) and dietary phosphorus-to-protein ratio (mg/g) with survival. (3) Results: In expanded case-mix + laboratory + nutrition adjusted analyses, the lowest tertile of dietary phosphorus intake was associated with higher mortality risk (ref: highest tertile): adjusted HR (aHR) (95% CI) 3.33 (1.75-6.33). In the analyses of dietary phosphorus scaled to 1000 kcal of energy intake, the lowest tertile of intake was associated with higher mortality risk compared to the highest tertile: aHR (95% CI) 1.74 (1.08, 2.80). Similarly, in analyses examining the association between dietary phosphorus-to-protein ratio, the lowest tertile of intake was associated with higher mortality risk compared to the highest tertile: aHR (95% CI) 1.67 (1.02-2.74). (4) Conclusions: A lower intake of dietary phosphorus was associated with higher mortality risk in a prospective hemodialysis cohort. Further studies are needed to clarify the relationship between specific sources of dietary phosphorus intake and mortality in this population.

Multilevel Varying Coefficient Spatiotemporal Model.

Over 785,000 individuals in the U.S. have end-stage renal disease (ESRD) with about 70% of patients on dialysis, a life-sustaining treatment. Dialysis patients experience frequent hospitalizations. In order to identify risk factors of hospitalizations, we utilize data from the large national database, United States Renal Data System (USRDS). To account for the hierarchical structure of the data, with longitudinal hospitalization rates nested in dialysis facilities and dialysis facilities nested in geographic regions across the U.S., we propose a multilevel varying coefficient spatiotemporal model (M-VCSM) where region- and facility-specific random deviations are modeled through a multilevel Karhunen-Loéve (KL) expansion. The proposed M-VCSM includes time-varying effects of multilevel risk factors at the region- (e.g., urbanicity and area deprivation index) and facility-levels (e.g., patient demographic makeup) and incorporates spatial correlations across regions via a conditional autoregressive (CAR) structure. Efficient estimation and inference is achieved through the fusion of functional principal component analysis (FPCA) and Markov Chain Monte Carlo (MCMC). Applications to the USRDS data highlight significant region- and facility-level risk factors of hospitalizations and characterize time periods and spatial locations with elevated hospitalization risk. Finite sample performance of the proposed methodology is studied through simulations.

Serum Thyrotropin Elevation and Coronary Artery Calcification in Hemodialysis Patients.

INTRODUCTION: Hypothyroidism is highly prevalent in end-stage kidney disease patients, and emerging data show that lower circulating thyroid hormone levels lead to downregulation of vascular calcification inhibitors and coronary artery calcification (CAC) in this population. To date, no studies have examined the association of serum thyrotropin (TSH), the most sensitive and specific single biochemical metric of thyroid function, with CAC risk in hemodialysis patients. METHODS: In secondary analyses of patients from the Anti-Inflammatory and Anti-Oxidative Nutrition in Hypoalbuminemic Dialysis Patients trial, we examined serum TSH levels and CAC risk assessed by cardiac computed tomography scans collected within a 90-day period. We evaluated the relationship between serum TSH with CAC Volume (VS) and Agatston score (AS) (defined as >100 mm3 and >100 Houndsfield Units, respectively) using multivariable logistic regression. RESULTS: Among 104 patients who met eligibility criteria, higher TSH levels in the highest tertile were associated with moderately elevated CAC VS and AS in case-mix-adjusted analyses (ref: lowest tertile): adjusted ORs (95% CIs) 4.26 (1.18, 15.40) and 5.53 (1.44, 21.30), respectively. TSH levels >3.0 mIU/L (ref: ≤3.0 mIU/L) were also associated with moderately elevated CAC VS and AS. In secondary analyses, point estimates of incrementally lower direct free thyroxine levels trended toward elevated CAC VS and AS, although associations did not achieve statistical significance. CONCLUSIONS: In hemodialysis patients, higher serum TSH was associated with elevated CAC VS and AS. Further studies are needed to determine if thyroid hormone supplementation can attenuate CAC burden in this population.

Dialysis symptom index burden and symptom clusters in a prospective cohort of dialysis patients.

BACKGROUND: Dialysis patients experience a high symptom burden, which may adversely impact their quality of life. Whereas other specialties emphasize routine symptom assessment, symptom burden is not well-characterized in dialysis patients. We sought to examine the prevalence and severity of unpleasant symptoms in a prospective hemodialysis cohort. METHODS: Among 122 hemodialysis patients from the prospective Malnutrition, Diet, and Racial Disparities in Chronic Kidney Disease (CKD) study, CKD-associated symptoms were ascertained by the Dialysis Symptom Index, a validated survey assessing symptom burden/severity (with higher scores indicating greater symptom severity), over 6/2020-10/2020. We examined the presence of (1) individual symptoms and symptom severity scores, and (2) symptom clusters (defined as ≥ 2 related concurrent symptoms), as well as correlations with clinical characteristics. RESULTS: Symptom severity scores were higher among non-Hispanic White and Hispanic patients, whereas scores were lower in Black and Asian/Pacific Islander patients. In the overall cohort, the most common individual symptoms included feeling tired/lack of energy (71.3%), dry skin (61.5%), trouble falling asleep (44.3%), muscle cramps (42.6%), and itching (42.6%), with similar patterns observed across racial/ethnic groups. The most prevalent symptom clusters included feeling tired/lack of energy + trouble falling asleep (37.7%); trouble falling asleep + trouble staying asleep (34.4%); and feeling tired/lack of energy + trouble staying asleep (32.0%). Lower hemoglobin, iron stores, and dialysis adequacy correlated with higher individual and overall symptom severity scores. CONCLUSION: We observed a high prevalence of unpleasant symptoms and symptom clusters in a diverse hemodialysis cohort. Further studies are needed to identify targeted therapies that ameliorate symptom burden in CKD.

Variation across centers in standardized mortality ratios for congenital diaphragmatic hernia receiving extracorporeal life support.

BACKGROUND: We sought to elucidate the degree of variation across centers by calculating center-specific standardized mortality ratios (SMRs) for infants with congenital diaphragmatic hernia (CDH) requiring extracorporeal life support (ECLS). METHODS: The Extracorporeal Life Support Organization (ELSO) registry data (2000-2019) were used to estimate SMRs. Center-specific SMRs and their 95% confidence intervals (CIs) were used to identify centers with mortality as significantly worse (SW), significantly better (SB), or not different (ND) relative to the median standardized mortality rate. RESULTS: We identified 4,223 neonates with CDH from 109 centers. SMRs were risk-adjusted for pre-ECLS case-mix (birthweight, sex, race, 5 min Apgar, blood gases, gestational age, hernia side, prenatal diagnosis, pre-ECLS arrest, and comorbidities). Observed (unadjusted) mortality rates across centers varied substantially (range: 14.3%-90.9%; interquartile range [IQR]: 42.9%-62.1%). Thirteen centers (11.9%) had SB SMRs< 1 (SMR 0.52 to 0.84), 7 centers (6.4%) had SW SMRs>1 (SMR 1.25 to 1.43), and 89 centers (81.7%) had SMRs ND relative to the median SMR rate across all centers (i.e., SMR not different from one). Descriptive analyses demonstrated that SB centers had a lower proportion of cases with renal complications, infectious complications and discontinuation of ECLS owing to complications, as well as differences in pre-ECLS treatments and timing of CDH repair, compared to SW and ND centers. CONCLUSION: This study specifically identified ECLS centers with higher and lower survival for patients with CDH, which may serve as a benchmark for institutional quality improvement. Future studies are needed to identify those specific processes at those centers that leads to favorable outcomes with the goal of improving care globally. LEVEL OF EVIDENCE: Level III.

The Use of Putative Dialysis Initiation Time in Comparative Outcomes of Patients with Advanced Chronic Kidney Disease: Methodological Aspects.

The latest data from the United States Renal Data Systems show over 134,000 individuals with end-stage kidney disease (ESKD) starting dialysis in the year 2019. ESKD patients on dialysis, the default treatment strategy, have high mortality and hospitalization, especially in the first year of dialysis. An alternative treatment strategy is (non-dialysis) conservative management (CM). The relative effectiveness of CM with respect to various patient outcomes, including survival, hospitalization, and health-related quality of life among others, especially in elderly ESKD or advanced chronic kidney disease patients with serious comorbidities, is an active area of research. A technical challenge inherent in comparing patient outcomes between CM and dialysis patient groups is that the start of follow-up time is "not defined" for patients on CM because they do not initiate dialysis. One solution is the use of putative dialysis initiation (PDI) time. In this work, we examine the validity of the use of PDI time to determine the start of follow-up for longitudinal retrospective and prospective cohort studies involving CM. We propose and assess the efficacy of estimating PDI time using linear mixed effects model of kidney function decline over time via simulation studies. We also illustrate how the estimated PDI time can be used to effectively estimate the survival distribution.