Associations Between Social Support and Patient-Reported Outcomes in Hemodialysis Patients: Results from the TACcare Study.

BACKGROUND: End Stage Kidney Disease (ESKD) patients experience high symptom burden which has been associated with a negative impact on their interpersonal relationships. However, there is limited research exploring associations of social support and patient-reported outcomes among hemodialysis (HD) patients. METHODS: The current study is a secondary, cross-sectional analyses of the sociodemographic and clinical correlates of perceived social support (Multidimensional Scale of Perceived Social Support; MSPSS) at baseline. The study examined the extent to which perceived social support is associated with pain, depression, fatigue, anxiety, sleep, and HRQoL (SF-12 Mental Component Score; MCS) and Physical Component Score; PCS)). RESULTS: Of the 160 randomized patients: mean (SD) age was 58 ±14 years; years on dialysis was 4.1 + 4.2; 45% were female; 29% Black, 13% American Indian, 18% Hispanic; 88% had at least high school education; and 27% were married. Mean baseline levels of perceived social support were comparable to other chronically ill populations. At least a high school education (p = 0.04) and being married (p = 0.05) were associated with higher total MSPSS scores. Higher MSPSS scores were correlated with lower levels of fatigue (r = 0.21, p =0.008; higher fatigue scores signify lower fatigue), pain (r = -0.17, p = 0.03), depressive symptoms (r = -0.26, p < 0.001), anxiety (r = -0.23, p = 0.004), better sleep quality (r = -0.32, p < 0.001) and SF-12 MCS (r = 0.26, p <0.001). Moderation analyses revealed male sex and non-Hispanic ethnicity resulted in stronger positive associations of perceived social support with SF-12 MCS. CONCLUSIONS: The level of perceived social support observed among thrice weekly HD patients in TACcare was similar to those observed in other chronic conditions. Because of the associations between perceived social support and patient-reported outcomes, particularly psychosocial and behavioral health outcomes, targeting social support appears to be warranted among HD patients.

Effects of Technology Assisted Stepped Collaborative Care Intervention to Improve Symptoms in Patients Undergoing Hemodialysis: The TACcare Randomized Clinical Trial.

Importance: Patients with end-stage kidney disease (ESKD) undergoing long-term hemodialysis often experience a high burden of debilitating symptoms for which effective treatment options are limited. Objective: To compare the effectiveness of a stepped collaborative care intervention vs attention control for reducing fatigue, pain, and depression among patients with ESKD undergoing long-term hemodialysis. Design, Setting, and Participants: Technology Assisted Stepped Collaborative Care (TACcare) was a parallel-group, single-blinded, randomized clinical trial of adult (≥18 years) patients undergoing long-term hemodialysis and experiencing clinically significant levels of fatigue, pain, and/or depression for which they were considering treatment. The trial took place in 2 US states (New Mexico and Pennsylvania) from March 1, 2018, to June 31, 2022. Data analyses were performed from July 1, 2022, to April 10, 2023. Interventions: The intervention group received 12 weekly sessions of cognitive behavioral therapy delivered via telehealth in the hemodialysis unit or patient home, and/or pharmacotherapy using a stepped approach in collaboration with dialysis and primary care teams. The attention control group received 6 telehealth sessions of health education. Main Outcomes and Measures: The coprimary outcomes were changes in fatigue (measured using the Functional Assessment of Chronic Illness Therapy Fatigue), average pain severity (Brief Pain Inventory), and/or depression (Beck Depression Inventory-II) scores at 3 months. Patients were followed up for 12 months to assess maintenance of intervention effects. Results: There were 160 participants (mean [SD] age, 58 [14] years; 72 [45%] women and 88 [55%] men; 21 [13%] American Indian, 45 [28%] Black, 28 [18%] Hispanic, and 83 [52%] White individuals) randomized, 83 to the intervention and 77 to the control group. In the intention-to-treat analyses, when compared with controls, patients in the intervention group experienced statistically and clinically significant reductions in fatigue (mean difference [md], 2.81; 95% CI, 0.86 to 4.75; P = .01) and pain severity (md, -0.96; 95% CI, -1.70 to -0.23; P = .02) at 3 months. These effects were sustained at 6 months (md, 3.73; 95% CI, 0.87 to 6.60; P = .03; and BPI, -1.49; 95% CI, -2.58 to -0.40; P = .02). Improvement in depression at 3 months was statistically significant but small (md -1.73; 95% CI, -3.18 to -0.28; P = .02). Adverse events were similar in both groups. Conclusions and Relevance: This randomized clinical trial found that a technology assisted stepped collaborative care intervention delivered during hemodialysis led to modest but clinically meaningful improvements in fatigue and pain at 3 months vs the control group, with effects sustained until 6 months. Trial Registration: ClinicalTrials.gov Identifier: NCT03440853.

Characterization of Risk Prediction Models for Acute Kidney Injury: A Systematic Review and Meta-analysis.

Importance: Despite the expansion of published prediction models for acute kidney injury (AKI), there is little evidence of uptake of these models beyond their local derivation nor data on their association with patient outcomes. Objective: To systematically review published AKI prediction models across all clinical subsettings. Data Sources: MEDLINE via PubMed (January 1946 to April 2021) and Embase (January 1947 to April 2021) were searched using medical subject headings and text words related to AKI and prediction models. Study Selection: All studies that developed a prediction model for AKI, defined as a statistical model with at least 2 predictive variables to estimate future occurrence of AKI, were eligible for inclusion. There was no limitation on study populations or methodological designs. Data Extraction and Synthesis: Two authors independently searched the literature, screened the studies, and extracted and analyzed the data following the Preferred Reporting Items for Systematic Review and Meta-analyses guideline. The data were pooled using a random-effects model, with subgroups defined by 4 clinical settings. Between-study heterogeneity was explored using multiple methods, and funnel plot analysis was used to identify publication bias. Main Outcomes and Measures: C statistic was used to measure the discrimination of prediction models. Results: Of the 6955 studies initially identified through literature searching, 150 studies, with 14.4 million participants, met the inclusion criteria. The study characteristics differed widely in design, population, AKI definition, and model performance assessments. The overall pooled C statistic was 0.80 (95% CI, 0.79-0.81), with pooled C statistics in different clinical subsettings ranging from 0.78 (95% CI, 0.75-0.80) to 0.82 (95% CI, 0.78-0.86). Between-study heterogeneity was high overall and in the different clinical settings (eg, contrast medium-associated AKI: I2 = 99.9%; P < .001), and multiple methods did not identify any clear sources. A high proportion of models had a high risk of bias (126 [84.4%]) according to the Prediction Model Risk Of Bias Assessment Tool. Conclusions and Relevance: In this study, the discrimination of the published AKI prediction models was good, reflected by high C statistics; however, the wide variation in the clinical settings, populations, and predictive variables likely drives the highly heterogenous findings that limit clinical utility. Standardized procedures for development and validation of prediction models are urgently needed.

Utilization and Outcomes of Clinically Indicated Invasive Cardiac Care in Veterans with Acute Coronary Syndrome and Chronic Kidney Disease.

SIGNIFICANCE STATEMENT: Of studies reporting an association of CKD with lower use of invasive cardiac care to treat acute coronary syndrome (ACS), just one accounted for the appropriateness of such care. However, its findings in patients hospitalized nearly 30 years ago may not apply to current practice. In a more recent cohort of 64,695 veterans hospitalized with ACS, CKD was associated with a 32% lower likelihood of receiving invasive care determined to be clinically indicated. Among patients with CKD, not receiving such care was associated with a 1.39-fold higher risk of 6-month mortality. Efforts to elucidate the reasons for this disparity in invasive care in patients with ACS and CKD and implement tailored interventions to enhance its use in this population may offer the potential to improve clinical outcomes. BACKGROUND: Previous studies have shown that patients with CKD are less likely than those without CKD to receive invasive care to treat acute coronary syndrome (ACS). However, few studies have accounted for whether such care was clinically indicated or assessed whether nonuse of such care was associated with adverse health outcomes. METHODS: We conducted a retrospective cohort study of US veterans who were hospitalized at Veterans Affairs Medical Centers from January 2013 through December 2017 and received a discharge diagnosis of ACS. We used multivariable logistic regression to investigate the association of CKD with use of invasive care (coronary angiography, with or without revascularization; coronary artery bypass graft surgery; or both) deemed clinically indicated based on Global Registry of Acute Coronary Events 2.0 risk scores that denoted a 6-month predicted all-cause mortality ≥5%. Using propensity scoring and inverse probability weighting, we examined the association of nonuse of clinically indicated invasive care with 6-month all-cause mortality. RESULTS: Among 34,430 patients with a clinical indication for invasive care, the 18,780 patients with CKD were less likely than the 15,650 without CKD to receive such care (adjusted odds ratio, 0.68; 95% confidence interval, 0.65 to 0.72). Among patients with CKD, nonuse of invasive care was associated with higher risk of 6-month all-cause mortality (absolute risk, 21.5% versus 15.5%; absolute risk difference 6.0%; adjusted risk ratio, 1.39; 95% confidence interval, 1.29 to 1.49). Findings were consistent across multiple sensitivity analyses. CONCLUSIONS: In contemporary practice, veterans with CKD who experience ACS are less likely than those without CKD to receive clinically indicated invasive cardiac care. Nonuse of such care is associated with increased mortality.

The Relationship between Rate and Volume of Intravenous Fluid Administration and Kidney Outcomes after Angiography.

BACKGROUND AND OBJECTIVES: Contrast-associated AKI may result in higher morbidity and mortality. Intravenous fluid administration remains the mainstay for prevention. There is a lack of consensus on the optimal administration strategy. We studied the association of periprocedure fluid administration with contrast-associated AKI, defined as an increase in serum creatinine of at least 25% or 0.5 mg/dl from baseline at 3-5 days after angiography, and 90-day need for dialysis, death, or a 50% increase in serum creatinine. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a secondary analysis of 4671 PRESERVE participants who underwent angiographic procedures. Although fluid type was randomized, strategy of administration was at the discretion of the clinician. We divided the study cohort into quartiles by total fluid volume. We performed multivariable logistic regression, adjusting for clinically important covariates. We tested for the interaction between fluid volume and duration of fluid administration, categorized as <6 or ≥6 hours. RESULTS: The mean (SD) age was 70 (8) years, 94% of participants were male, and median (interquartile range) eGFR was 60 (41-60) ml/min per 1.73 m2. The range of fluid administered was 89-882 ml in quartile 1 and 1258-2790 ml in quartile 4. Compared with the highest quartile (quartile 4) of fluid volume, we found a significantly higher risk of the primary outcome in quartile 1 (adjusted odds ratio, 1.58; 95% confidence interval, 1.06 to 2.38) but not in quartiles 2 and 3 compared with quartile 4. There was no difference in the incidence of contrast-associated AKI across the quartiles. The interaction between volume and duration was not significant for any of the outcomes. CONCLUSIONS: We found that administration of a total volume of 1000 ml, starting at least 1 hour before contrast injection and continuing postcontrast for a total of 6 hours, is associated with a similar risk of adverse outcomes as larger volumes of intravenous fluids administered for periods >6 hours. Mean fluid volumes <964 ml may be associated with a higher risk for the primary outcome, although residual confounding cannot be excluded.

Radiographic Contrast Media and the Kidney.

AKI is a potential complication of intravascular iodinated contrast exposure. Contrast-associated AKI, which typically manifests as small and transient decrements in kidney function that develop within several days of contrast administration, is associated with serious adverse outcomes, including progressive kidney dysfunction and death. However, a causal link between the small increases in serum creatinine that characteristically occur with contrast-associated AKI and serious adverse outcomes remains unproven. This is important given mounting evidence that clinically indicated, potentially lifesaving radiographic procedures are underutilized in patients with CKD. This has been hypothesized to be related to provider concern about precipitating contrast-associated AKI. Intravascular gadolinium-based contrast, an alternative to iodinated contrast that is administered with magnetic resonance imaging, has also been linked with potential serious adverse events, notably the development of nephrogenic systemic fibrosis in patients with severe impairment in kidney function. Patients hospitalized in the intensive care unit frequently have clinical indications for diagnostic and therapeutic procedures that involve the intravascular administration of contrast media. Accordingly, critical care providers and others treating critically ill patients should possess a sound understanding of the risk factors for and incidence of such outcomes, the ability to perform evidence-based risk-benefit assessments regarding intravascular contrast administration, and knowledge of empirical data on the prevention of these iatrogenic complications.

Nomenclature in nephrology: preserving 'renal' and 'nephro' in the glossary of kidney health and disease.

A recently published nomenclature by a "Kidney Disease Improving Global Outcomes" (KDIGO) Consensus Conference suggested that the word "kidney" should be used in medical writings instead of "renal" or "nephro" when referring to kidney disease and kidney health. Whereas the decade-old move to use "kidney" more frequently should be supported when communicating with the public-at-large, such as the World Kidney Day, or in English speaking countries in communications with patients, care-partners, and non-medical persons, our point of view is that "renal" or "nephro" should not be removed from scientific and technical writings. Instead, the terms can coexist and be used in their relevant contexts. Cardiologists use "heart" and "cardio" as appropriate such as "heart failure" and "cardiac care units" and have not replaced "cardiovascular" with "heartvessel", for instance. Likewise, in nephrology, we consider that "chronic kidney disease" and "continuous renal replacement therapy" should coexist. We suggest that in scientific writings and technical communications, the words "renal" and "nephro" and their derivatives are more appropriate and should be freely used without any pressure by medical journals to compel patients, care-partners, healthcare providers, researchers and other stakeholders to change their selected words and terminologies. We call to embrace the terms "kidney", "renal" and "nephro" as they are used in different contexts and ask that scientific and medical journals not impose terminology restrictions for kidney disease and kidney health. The choice should be at the discretion of the authors, in the different contexts including in scientific journals.

Source of Post-Transplant Care and Mortality among Kidney Transplant Recipients Dually Enrolled in VA and Medicare.

BACKGROUND AND OBJECTIVES: Many kidney transplant recipients enrolled in the Veterans Health Administration are also enrolled in Medicare and eligible to receive both Veterans Health Administration and private sector care. Where these patients receive transplant care and its association with mortality are unknown. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a retrospective cohort study of veterans who underwent kidney transplantation between 2008 and 2016 and were dually enrolled in Veterans Health Administration and Medicare at the time of surgery. We categorized patients on the basis of the source of transplant-related care (i.e., outpatient transplant visits, immunosuppressive medication prescriptions, calcineurin inhibitor measurements) delivered during the first year after transplantation defined as Veterans Health Administration only, Medicare only (i.e., outside Veterans Health Administration using Medicare), or dual care (mixed use of Veterans Health Administration and Medicare). Using multivariable Cox regression, we examined the independent association of post-transplant care source with mortality at 5 years after kidney transplantation. RESULTS: Among 6206 dually enrolled veterans, 975 (16%) underwent transplantation at a Veterans Health Administration hospital and 5231 (84%) at a non-Veterans Health Administration hospital using Medicare. Post-transplant care was received by 752 patients (12%) through Veterans Health Administration only, 2092 (34%) through Medicare only, and 3362 (54%) through dual care. Compared with patients who were Veterans Health Administration only, 5-year mortality was significantly higher among patients who were Medicare only (adjusted hazard ratio, 2.2; 95% confidence interval, 1.5 to 3.1) and patients who were dual care (adjusted hazard ratio, 1.5; 95% confidence interval, 1.1 to 2.1). CONCLUSIONS: Most dually enrolled veterans underwent transplantation at a non-Veterans Health Administration transplant center using Medicare, yet many relied on Veterans Health Administration for some or all of their post-transplant care. Veterans who received Veterans Health Administration-only post-transplant care had the lowest 5-year mortality.

Postangiography Increases in Serum Creatinine and Biomarkers of Injury and Repair.

BACKGROUND AND OBJECTIVES: It is unknown whether iodinated contrast causes kidney parenchymal damage. Biomarkers that are more specific to nephron injury than serum creatinine may provide insight into whether contrast-associated AKI reflects tubular damage. We assessed the association between biomarker changes after contrast angiography with contrast-associated AKI and 90-day major adverse kidney events and death. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a longitudinal analysis of participants from the biomarker substudy of the Prevention of Serious Adverse Events following Angiography trial. We measured injury (kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, IL-18) and repair (monocyte chemoattractant protein-1, uromodulin, YKL-40) proteins from plasma and urine samples at baseline and 2-4 hours postangiography. We assessed the associations between absolute changes and relative ratios of biomarkers with contrast-associated AKI and 90-day major adverse kidney events and death. RESULTS: Participants (n=922) were predominately men (97%) with diabetes (82%). Mean age was 70±8 years, and eGFR was 48±13 ml/min per 1.73 m2; 73 (8%) and 60 (7%) participants experienced contrast-associated AKI and 90-day major adverse kidney events and death, respectively. No postangiography urine biomarkers were associated with contrast-associated AKI. Postangiography plasma kidney injury molecule-1 and IL-18 were significantly higher in participants with contrast-associated AKI compared with those who did not develop contrast-associated AKI: 428 (248, 745) versus 306 (179, 567) mg/dl; P=0.04 and 325 (247, 422) versus 280 (212, 366) mg/dl; P=0.009, respectively. The majority of patients did not experience an increase in urine or plasma biomarkers. Absolute changes in plasma IL-18 were comparable in participants with contrast-associated AKI (-30 [-71, -9] mg/dl) and those without contrast-associated AKI (-27 [-53, -10] mg/dl; P=0.62). Relative ratios of plasma IL-18 were also comparable in participants with contrast-associated AKI (0.91; 0.86, 0.97) and those without contrast-associated AKI (0.91; 0.85, 0.96; P=0.54). CONCLUSIONS: The lack of significant differences in the absolute changes and relative ratios of injury and repair biomarkers by contrast-associated AKI status suggests that the majority of mild contrast-associated AKI cases may be driven by hemodynamic changes at the kidney.

Contrast-Associated Acute Kidney Injury and Serious Adverse Outcomes Following Angiography.

BACKGROUND: Contrast-associated acute kidney injury (CA-AKI) associates with an increased relative risk for serious adverse outcomes. However, the magnitude of this risk and the incidence of clinically significant CA-AKI derived from analyses of large cohorts with prospective assessment of CA-AKI and subsequent outcomes are unknown. OBJECTIVES: This study sought to characterize the relative risk for and incidence of serious adverse outcomes following the development of CA-AKI and to explore whether CA-AKI mediates the association of pre-angiography estimated glomerular filtration rate with adverse outcomes. METHODS: Among 4,418 participants in the PRESERVE (Prevention of Serious Adverse Outcomes Following Angiography) trial with comprehensive baseline and outcome data, we assessed whether CA-AKI was associated with the 90-day outcome comprising death, need for dialysis, or persistent impairment in kidney function. We calculated the incidence of clinically significant CA-AKI (i.e., proportion of patients who developed CA-AKI and the 90-day outcome) and examined whether CA-AKI was a mediator of the association of baseline kidney function with the 90-day outcome. RESULTS: CA-AKI was associated with an increased relative risk for 90-day death, need for dialysis, or persistent kidney impairment (odds ratio: 3.93; 95% confidence interval: 2.82 to 5.49; p < 0.0001). The incidence of clinically significant CA-AKI was 1.2% (53 of 4,418 patients). CA-AKI was not a mediator of the association of pre-angiography estimated glomerular filtration rate with the primary outcome. CONCLUSIONS: Whereas CA-AKI is associated with an increased relative risk of serious, adverse 90-day outcomes, the incidence of clinically significant CA-AKI is very low. CA-AKI does not mediate the association of the pre-angiography estimated glomerular filtration rate with these outcomes.

A Simple Equation to Estimate Urinary Flow Rate Using Urine Creatinine.

BACKGROUND: Accurate assessment of urine flow remains challenging in both inpatient and outpatient settings. We hypothesized we could derive an equation that would accurately estimate urine flow rate (eV) through derivation from other existing equations commonly used in nephrology clinical practice. METHODS: The eV equation was derived using the Cockcroft-Gault and the measured creatinine clearance (CrCl = UCrV/PCr) equations. Within the African American Study of Kidney Disease and Hypertension (AASK; n = 570) and COMBINE (n = 133) clinical trials, we identified participants with concordant estimated and measured creatinine excretion rates to define a subset with highly accurate 24-h urine collections, to assure a reliable gold standard. We then compared eV to measured 24-h urine flow rates in these trials. RESULTS: In AASK, we found a high correlation between eV and measured urine flow rate (V; r = 0.91, p < 0.001); however, Bland-Altman plots showed that eV was 9.5 mL/h lower than V, on average. Thus, we added a correction factor to the eV equation and externally validated the new equation in COMBINE. eV and V were again highly correlated (r = 0.91, p < 0.001), and bias was improved (mean difference 5.3 mL/h). Overall, 80% of individuals had eV that was within 20% of V. CONCLUSIONS: A simple equation using urine creatinine, demographics, and body weight can accurately predict urine flow rate and may have clinical utility in situations where it is difficult to accurately measure the urine flow rate.

Soluble Urokinase Receptor and Acute Kidney Injury.

BACKGROUND: Acute kidney injury is common, with a major effect on morbidity and health care utilization. Soluble urokinase plasminogen activator receptor (suPAR) is a signaling glycoprotein thought to be involved in the pathogenesis of kidney disease. We investigated whether a high level of suPAR predisposed patients to acute kidney injury in multiple clinical contexts, and we used experimental models to identify mechanisms by which suPAR acts and to assess it as a therapeutic target. METHODS: We measured plasma levels of suPAR preprocedurally in patients who underwent coronary angiography and patients who underwent cardiac surgery and at the time of admission to the intensive care unit in critically ill patients. We assessed the risk of acute kidney injury at 7 days as the primary outcome and acute kidney injury or death at 90 days as a secondary outcome, according to quartile of suPAR level. In experimental studies, we used a monoclonal antibody to urokinase plasminogen activator receptor (uPAR) as a therapeutic strategy to attenuate acute kidney injury in transgenic mice receiving contrast material. We also assessed cellular bioenergetics and generation of reactive oxygen species in human kidney proximal tubular (HK-2) cells that were exposed to recombinant suPAR. RESULTS: The suPAR level was assessed in 3827 patients who were undergoing coronary angiography, 250 who were undergoing cardiac surgery, and 692 who were critically ill. Acute kidney injury developed in 318 patients (8%) who had undergone coronary angiography. The highest suPAR quartile (vs. the lowest) had an adjusted odds ratio of 2.66 (95% confidence interval [CI], 1.77 to 3.99) for acute kidney injury and 2.29 (95% CI, 1.71 to 3.06) for acute kidney injury or death at 90 days. Findings were similar in the surgical and critically ill cohorts. The suPAR-overexpressing mice that were given contrast material had greater functional and histologic evidence of acute kidney injury than wild-type mice. The suPAR-treated HK-2 cells showed heightened energetic demand and mitochondrial superoxide generation. Pretreatment with a uPAR monoclonal antibody attenuated kidney injury in suPAR-overexpressing mice and normalized bioenergetic changes in HK-2 cells. CONCLUSIONS: High suPAR levels were associated with acute kidney injury in various clinical and experimental contexts. (Funded by the National Institutes of Health and others.).

Hemodialysis access cost comparisons among incident tunneled catheter patients.

BACKGROUND: Arteriovenous fistula is the ideal hemodialysis access, but most patients start with tunneled dialysis catheter. Arteriovenous fistula and arteriovenous graft surgery may reduce tunneled dialysis catheter use and also increase procedural expenses. We compared Medicare costs associated with arteriovenous fistula, arteriovenous graft, and tunneled dialysis catheter. METHODS: Using the US Renal Data System, we identified incident hemodialysis patients in 2008 who started with tunneled dialysis catheter, survived at least 90 days, and had adequate Medicare records for analysis. We followed them until death or end of 2011; access modality was based on billing evidence of arteriovenous fistula or arteriovenous graft creation. We assumed patients without such records remained with tunneled dialysis catheter. We generated multivariate linear regression models predicting Medicare expenditures, censoring costs when patients died; we included all payments to physicians and institutions. We also created algorithms to identify access-related costs. RESULTS: There were 113,505 patients in the US Renal Data System who started hemodialysis in 2008, of whom 51,002 Medicare patients met inclusion criteria. Of that group, 41,532 (81%) began with tunneled dialysis catheter; 27,064 patients were in the final analysis file. In the first 90 days after hemodialysis initiation, 6100 (22.5%) received arteriovenous fistula, 1813 (6.7%) arteriovenous graft, and 19,151 (70.8%) stayed with tunneled dialysis catheter. Annualized access costs by modality were tunneled dialysis catheter US$13,625 (95% confidence interval: US$13,426-US$13,285); arteriovenous fistula US$16,864 (95% confidence interval: US$16,533-US$17,194); and arteriovenous graft US$20,961 (95% confidence interval: US$20,967-US$21,654; p < .001). Multivariate linear regression demonstrated that staying with tunneled dialysis catheter had lowest access-related costs, arteriovenous fistula was intermediate, and those who underwent arteriovenous graft surgery were highest (p < .021). Access type was not significantly associated with total costs. Additional arteriovenous fistula and arteriovenous graft creation (US$3525 and US$3804 per access per year, respectively) and open and endovascular access-related interventions (US$3102 and US$3569 per procedure per year, respectively; all p < .001) were important predictors of increased cost. CONCLUSIONS: Among patients starting hemodialysis with tunneled dialysis catheter, continued tunneled dialysis catheter use is associated with lowest access-related cost. Both endovascular and open interventions are associated with significant additional costs. Further investigation is warranted to develop efficient patient-centered strategies for hemodialysis access.

Kidney Biomarkers of Injury and Repair as Predictors of Contrast-Associated AKI: A Substudy of the PRESERVE Trial.

RATIONALE & OBJECTIVE: The PRESERVE trial used a 2 × 2 factorial design to compare intravenous saline solution with intravenous sodium bicarbonate solution and oral N-acetylcysteine with placebo for the prevention of 90-day major adverse kidney events and death (MAKE-D) and contrast-associated acute kidney injury (CA-AKI) among patients with chronic kidney disease undergoing angiography. In this ancillary study, we evaluated the predictive capacities of preangiography injury and repair proteins in urine and plasma for MAKE-D, CA-AKI, and their impact on trial design. STUDY DESIGN: Longitudinal analysis. SETTING & PARTICIPANTS: A subset of participants from the PRESERVE trial. EXPOSURES: Injury (KIM-1, NGAL, and IL-18) and repair (MCP-1, UMOD, and YKL-40) proteins in urine and plasma 1 to 2 hours preangiography. OUTCOMES: MAKE-D and CA-AKI. ANALYTICAL APPROACH: We analyzed the associations of preangiography biomarkers with MAKE-D and with CA-AKI. We evaluated whether the biomarker levels could enrich the MAKE-D event rate and improve future clinical trial efficiency through an online biomarker prognostic enrichment tool available at prognosticenrichment.com. RESULTS: We measured plasma biomarkers in 916 participants and urine biomarkers in 797 participants. After adjusting for urinary albumin-creatinine ratio and baseline estimated glomerular filtration rate, preangiography levels of 4 plasma (KIM-1, NGAL, UMOD, and YKL-40) and 3 urine (NGAL, IL-18, and YKL-40) biomarkers were associated with MAKE-D. Only plasma KIM-1 level was significantly associated with CA-AKI after adjustment. Biomarker levels provided modest discriminatory capacity for MAKE-D. Screening patients using the 50th percentile of preangiography plasma KIM-1 or YKL-40 levels would have reduced the required sample size by 30% (∼2,000 participants). LIMITATIONS: Evaluation of prognostic enrichment does not account for changing trial costs, time needed to screen patients, or loss to follow-up. Most participants were male, limiting the generalizability of our findings. CONCLUSIONS: Preangiography levels of injury and repair biomarkers modestly predict the development of MAKE-D and can be used to improve the efficiency of future CA-AKI trials.

Intravascular Iodinated Contrast Is an Independent Cause of Acute Kidney Injury Following Coronary Angiography.

OBJECTIVES: Recent studies have questioned whether intravascular iodinated contrast remains an independent cause of acute kidney injury (AKI). We sought to assess whether iodinated contrast administered during coronary angiography is an independent cause of AKI. METHODS: We identified all of the patients who underwent coronary angiography between July 1, 2015 and June 30, 2017 with a discharge diagnosis of AKI that developed within 7 days following angiography. Using chart review, we categorized patients as having multifactorial AKI if ≥1 insults other than intravascular contrast potentially contributed to kidney injury or contrast-induced AKI (CI-AKI) if the only insult was contrast administration. We compared the severity of AKI and renal function upon discharge between patients with CI-AKI and multifactorial AKI. RESULTS: We identified 78 patients who experienced AKI within 7 days following angiography, 10 (13%) of whom had CI-AKI and 68 of whom (87%) experienced multifactorial AKI. Nine (90%) patients with CI-AKI manifested stage 1 disease, 1 (10%) had stage 2 disease, and 9 (90%) experienced full recovery of kidney function. More patients with multifactorial AKI developed stage 2 or 3 disease (42% vs 10%, χ2 = 3.73, P = 0.05) and experienced either partial recovery of kidney function or persistent kidney impairment compared with patients with CI-AKI (25% vs 10%, χ2 = 1.9, P = 0.17), although the latter comparison was not statistically significant. CONCLUSIONS: The intravascular administration of iodinated contrast remains an independent cause of AKI. Compared with those with multifactorial AKI, patients with CI-AKI appear to be more likely to experience mild decrements in kidney function that recover completely.