Discrepancies between Cystatin C-Based and Creatinine-Based eGFR.

BACKGROUND: Recent guidance suggests clinicians increase use of cystatin C for the estimation of GFR. Discrepant levels of creatinine- versus cystatin C-based eGFR (eGFRcr versus eGFRcys) can occur and might signify inaccurate estimation of GFR using creatinine alone. This study sought to enhance the knowledge of the risk factors and clinical implications of having a large eGFR discrepancy. METHODS: Participants in the Atherosclerosis Risk in Communities Study, a prospective cohort study of US adults, were followed over 25 years. eGFR discrepancy was measured at five clinical visits and defined as eGFRcys either 30% lower or higher than eGFRcr, the current clinical standard of care. The associations between eGFR discrepancies and kidney-related laboratory parameters were assessed using linear and logistic regression and long-term adverse outcomes, including kidney failure, AKI, heart failure, and death, using Cox proportional hazards models. RESULTS: Among 13,197 individuals (mean age 57 [SD 6] years, 56% women, 25% Black race), 7% had eGFRcys 30% lower than eGFRcr at visit 2 (1990-1992), and this proportion increased over time to 23% by visit 6 (2016-2017). By contrast, the percent with eGFRcys 30% higher than eGFRcr was relatively stable (3%-1%). Independent risk factors for having eGFRcys 30% lower than eGFRcr included older age, female sex, non-Black race, higher eGFRcr, higher body mass index, weight loss, and current smoking. Those with eGFRcys 30% lower than eGFRcr had more anemia and higher uric acid, fibroblast growth factor 23, and phosphate levels as well as higher risk of subsequent mortality, kidney failure, AKI, and heart failure compared with those with similar eGFRcr and eGFRcys values. CONCLUSIONS: Having eGFRcys lower than eGFRcr was associated with worse kidney-related laboratory derangements and a higher risk of adverse health outcomes. PODCAST: This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_09_08_CJN0000000000000217.mp3.

Anemia Prevalence, Type, and Associated Risks in a Cohort of 5.0 Million Insured Patients in the United States by Level of Kidney Function.

RATIONALE & OBJECTIVE: Anemia is common in chronic kidney disease (CKD); although anemia is associated with adverse outcomes, the available treatments are not ideal. We characterized the burden, risk factors for, and risks associated with anemia by estimated glomerular filtration rate (eGFR) and hemoglobin level. STUDY DESIGN: Cross-sectional and prospective cohort study. SETTING & PARTICIPANTS: Outpatient data from 5,004,957 individuals across 57 health care centers in the United States from 2016 to 2019, extracted from the Optum Labs Data Warehouse. EXPOSURE: Severity of anemia, presence of low iron test results, eGFR. OUTCOME: Incident kidney failure with replacement therapy, cardiovascular disease, coronary heart disease, stroke, heart failure, death. ANALYTICAL APPROACH: The prevalences of anemia, low iron test results, vitamin B12 deficiency, and erythropoiesis-stimulating agent (ESA) use, stratified by sex and eGFR, were characterized. Polychotomous logistic regression was used to estimate the adjusted odds ratios of different hemoglobin levels across eGFR. Cox proportional hazards regression was used to calculate adjusted hazard ratios for adverse outcomes across hemoglobin level. RESULTS: The mean age was 54 years, and 42% were male. Lower eGFR was very strongly associated with increased prevalence of anemia, even after adjustment. Although iron studies were checked infrequently in patients with anemia, low iron test results were highly prevalent in those tested: 60.4% and 81.3% of men and women, respectively. ESA use was uncommon, with a prevalence of use of<4%. Lower hemoglobin was independently associated with increased risk of incident kidney failure with replacement therapy, cardiovascular disease, coronary heart disease, stroke, heart failure, and death. LIMITATIONS: Reliance on ICD codes for medical diagnoses, death information obtained from claims data, observational study. CONCLUSIONS: Severe anemia was common and strongly associated with lower eGFR and multiple adverse outcomes. Low-iron test results were highly prevalent in those tested despite iron studies being checked infrequently. ESA use in nondialysis CKD patients was uncommon.

High Risk of Prosthetic Valve Endocarditis and Death After Valve Replacement Operations in Dialysis Patients.

BACKGROUND: Despite a high burden of dialysis access-related bloodstream infections and an increasing incidence of endocarditis, few data are available addressing the risk of prosthetic valve endocarditis (PVE) in the dialysis population. We sought to assess the risk of PVE and death after valve replacement operations in patients receiving long-term dialysis. METHODS: A matched retrospective cohort study was conducted comprising patients admitted for valve replacement operations at two university hospitals. Patients without dialysis were matched 1:1 with dialysis patients by valve(s) replaced, year of operation, and presence of active endocarditis as the indication for valve replacement. Patient characteristics were compared using χ(2) and t tests. The development of PVE was defined by use of the modified Duke criteria and analyzed with Cox proportional hazards regression. RESULTS: Two hundred seventy-eight patients were included, with 139 in either cohort. The PVE risk per year of follow-up was 0.14 in the dialysis cohort and 0.03 in the nondialysis cohort. Dialysis remained a risk factor (adjusted hazard ratio 5.61 [95% confidence interval, 2.17 to 14.5], p = 0.0004) after age and race were controlled for. The 5-year survival rate was lower after valve replacement operation in the dialysis group (25.4%) than in the nondialysis group (75.9%, p < 0.001). CONCLUSIONS: The risk of PVE and death after valve replacement operations in dialysis patients is substantial and significantly higher than in patients without dialysis. These findings highlight the importance of a careful preoperative risk-benefit assessment and underscore the need to prevent hemodialysis-related bloodstream infections.