Burden of CKD-Associated Pruritus and Adverse Clinical Outcomes in Patients Receiving Dialysis: The Stockholm CREAtinine Measurements (SCREAM) Project.

RATIONALE & OBJECTIVE: Pruritus is a common but not well-characterized complaint of patients receiving maintenance dialysis. This study sought to quantify the burden of pruritus and its associated adverse health outcomes in this population. STUDY DESIGN: Observational study. SETTING & PARTICIPANTS: All patients receiving maintenance dialysis in Stockholm, Sweden, during 2005-2021. EXPOSURE: Clinically recognized pruritus, defined using ICD-10 codes or the prescription for anti-pruritus treatments (including UV-therapy). OUTCOMES: All-cause mortality, severe infection-related hospitalizations (composite of endocarditis, peritoneal dialysis-related peritonitis, hemodialysis/peritoneal dialysis-related catheter infection, sepsis due to Staphylococcus Spp., or skin infection) and incident diagnoses of anxiety/depression and sleep disorders. ANALYTICAL APPROACH: Multivariable logistic regression and cause-specific hazards models to analyze factors associated with prevalent and new-onset pruritus, respectively. Multivariable cause-specific hazards models with time-varying exposure to explore the association of prevalent and new-onset pruritus with adverse health outcomes. RESULTS: Among 3281 dialysis patients (median age 64 years, 66% men, 69% on hemodialysis,77% incident dialysis patients), 456 (14%) had pruritus at enrollment. During a median follow-up of 3.3 [IQR: 1.3-9.2] years, 539 (19%) additional patients developed pruritus. Older age, female sex, a lower serum albumin level, and higher C-reactive protein, serum calcium and phosphorus levels were independently associated with pruritus. Compared to patients without pruritus, patients with pruritus were at a higher risk of suffering sleep disorders (adjusted HR: 1.96 [95%CI 1.60-2.39]), developing anxiety/depression (aHR: 1.56 [1.23-1.98]), and being hospitalized for severe infections (aHR: 1.36 [1.18-1.57]), the latter attributed to higher risk of sepsis and peritoneal dialysis-related peritonitis. There was no detectable association between developing pruritus and all-cause mortality. LIMITATIONS: Potential misclassification bias if pruritus is not clinically recognized; lack of information on pruritus intensity/severity; use of diagnostic codes for exposure and outcome diagnoses. CONCLUSION: At least one-third of patients experience pruritus during their first years on dialysis, and pruritus was consistently associated with adverse health outcomes.

Handgrip strength and mortality in a cohort of kidney failure patients: Comparative analysis of different normalization methods.

OBJECTIVES: Reduced handgrip strength (HGS) is associated with adverse clinical outcomes. We analyzed and compared associations of HGS with mortality risk in dialysis patients, using different normalization methods of HGS. METHODS: HGS and clinical and laboratory parameters were measured in a cohort of 446 incident dialysis patients (median age 56 y, 62% men). The area under the receiver operating characteristic curve (AUROC) was used to compare different normalization methods of HGS as predictors of mortality: absolute HGS in kilograms; HGS normalized to height, weight, or body mass index; and HGS of a reference population of sex-matched controls (percentage of the mean HGS value [HGS%]). Multivariate linear regression analysis was used to assess HGS predictors. Competing risk regression analysis was used to evaluate 5-year all-cause mortality risk. Differences in survival time between HGS% tertiles were quantitated by analyzing the restricted mean survival time. RESULTS: The AUROC for HGS% was higher than the AUROCs for absolute or normalized HGS values. Compared with the high HGS% tertile, low HGS% (subdistribution hazard ratio [sHR] = 2.36; 95% CI, 1.19-3.70) and middle HGS% (sHR = 1.79; 95% CI, 1.12-2.74) tertiles were independently associated with higher all-cause mortality and those with high HGS% tertile survived on average 7.95 mo (95% CI, 3.61-12.28) and 18.99 mo (95% CI, 14.42-23.57) longer compared with middle and low HGS% tertile, respectively. CONCLUSIONS: HGS% was a strong predictor of all-cause mortality risk in incident dialysis patients and a better discriminator of survival than absolute HGS or HGS normalized to body size dimensions.

Heart failure: the grim reaper of the cardio-renal-metabolic triad.

AIMS: Current understanding of the prognosis for patients with chronic kidney disease (CKD) and overlapping cardio-renal-metabolic components, specifically heart failure (HF) and diabetes mellitus (DM), remains limited. While previous studies have explored the interactions between CKD, HF, and DM, they have predominantly focused on cohorts of HF or DM patients. This study aims to fill this gap by investigating the long-term outcomes and treatment patterns in a cohort of CKD patients, particularly those with coexisting HF and DM. METHODS AND RESULTS: We analysed data from the Swedish national CKD patient cohort, the Swedish Renal Registry, with a follow-up period extending up to 10 years. The study examined the risks of all-cause mortality, major adverse cardiovascular events (MACE)-defined as a composite of non-fatal myocardial infarction, hospitalization for congestive HF, non-fatal stroke, or cardiovascular death-and the initiation of kidney replacement therapy (KRT). Analyses were conducted using Cox proportional hazards and competing risk models. Among the 27 647 patients, 48% had CKD alone, 12% had CKD with HF, 27% had CKD with DM, and 13% had CKD with both HF and DM. After 5 years, mortality rates were 23% for patients with CKD, 30% for those with CKD/DM, 54% for CKD/HF, and 55% for CKD/HF/DM. The 10 year absolute risk of MACE was 28% for CKD alone, 35% for CKD/DM, 67% for CKD/HF, and 73% for CKD/HF/DM. The adjusted hazard ratio (HR) for mortality was approximately three times higher in patients with any HF combination, with HRs of 2.57 [95% confidence interval (CI) 2.43-2.71] for CKD/HF and 3.22 (95% CI 3.05-3.39) for CKD/HF/DM, compared with CKD alone. The impact of HF on MACE prognosis was even more pronounced, with adjusted sub-hazard ratios (SHRs) of 3.33 (95% CI 3.14-3.53) for CKD/HF and 4.26 (95% CI 4.04-4.50) for CKD/HF/DM. Additionally, CKD patients diagnosed with HF were less likely to commence KRT, and the risk of death prior to KRT initiation was roughly twice as high for these groups, with SHRs of 2.05 (95% CI 1.93-2.18) for CKD + HF and 2.43 (95% CI 2.29-2.58) for CKD + HF + DM. CONCLUSIONS: In a cohort of CKD patients, having HF contributes substantially to increased mortality and the risk of MACE, and these patients are less likely to start KRT. These findings highlight the urgent need for targeted therapeutic strategies and management plans for CKD patients, particularly those with concurrent HF, to enhance patient prognosis.

Levels of Cell-Free DNA in Kidney Failure Patients before and after Renal Transplantation.

Circulating cell-free DNA (cfDNA) has diverse applications in oncological, prenatal, toxicological, cardiovascular, and autoimmune diseases, diagnostics, and organ transplantation. In particular, mitochondrial cfDNA (mt-cfDNA) is associated with inflammation and linked to early vascular ageing (EVA) in end-stage kidney failure (ESKF), which could be a noninvasive marker for graft rejection and organ damage. Plasma samples from 44 ESKF patients, of whom half (n = 22) underwent either conservative therapy (non-HD) or hemodialysis (HD) before kidney transplantation (KT). These samples were analyzed at baseline and two years after KT. cfDNA was extracted from plasma and quantified using the fluorometric method. qPCR was used to quantify and differentiate the fractions of mt-cfDNA and nuclear cfDNA (nc-cfDNA). mt-cfDNA levels in KT patients decreased significantly from baseline to two years post-KT (p < 0.0268), while levels of total cfDNA and nc-cfDNA did not differ. Depending on therapy modality (HD vs. non-HD) before KT, total cfDNA levels were higher in HD patients at both baseline (p = 0.0133) and two years post-KT (p = 0.0421), while nc-cfDNA levels were higher in HD only at baseline (p = 0.0079). Males showed a nonsignificant trend of higher cfDNA levels. Patients with assessed vascular fibrosis (p = 0.0068), either alone or in combination with calcification plus fibrosis, showed reduced mt-cfDNA post-KT (p = 0.0195). Changes in mt-cfDNA levels suggests the impact of KT on the inflammatory state of ESKF, as evidenced via its correlation with high sensitivity C-reactive protein after KT. Further studies are warranted to assess if cfDNA could serve as a noninvasive method for monitoring the response to organ transplantation and even for amelioration of EVA status per se.

Lifelong statins for long life in dialysis patients?

Dyslipidemia in chronic kidney disease (CKD) contributes to the increasing cardiovascular risk during progression of the disease. Statins reduces the risk of ischemic cardiovascular events in CKD patients not treated with dialysis and treatment is generally recommended in patients above 50 years old. In CKD patients on maintenance dialysis treatment, it is not recommended to initiate statins based on evidence from randomized clinical trials. In an article by Marx et al. in this issue of CKJ, a post hoc analysis of cardiovascular events in the 4D study of dialysis patients with diabetes mellitus shows different time trends for events in statin-treated patients compared with those in the placebo group. Although the numbers of cardiovascular events were not different, the risk increased over time in the placebo group whereas it stabilized after 1.5 years and remained constant in the atorvastatin group. In this Editorial we discuss this analysis in the context of current guidelines and clinical practice in dialysis patients.

Poor recognition and undertreatment of anemia in patients with chronic kidney disease managed in primary care.

BACKGROUND: Anemia is a common complication of chronic kidney disease (CKD), but limited awareness and treatment options may hinder its management among CKD patients followed in primary care. METHODS: We evaluated adults with CKD stages 3-5 attending primary care in Stockholm, Sweden, 2012-2018. We assessed the incidence of anemia, clinical reactions, and association with subsequent major adverse cardiovascular events (MACE) and death. RESULTS: We identified 45,637 patients with CKD stages 3-5 free from anemia (mean age 78 years; 64% females; 79% CKD stage 3b). During a median follow-up of 2.4 years, 26% of patients developed anemia, and 10.4% developed severe anemia (hemoglobin <10 g/dL). Within 6 months from the anemia event, iron tests were infrequent; ferritin and transferrin saturation were tested in 27% and 11% of anemia cases, respectively, and 49% and 24% of severe anemia cases. Few patients were recognized with a clinical diagnosis (15% of anemia cases; 68% of severe anemias). Only 19% of patients with anemia received treatment, primarily iron (10%) and blood transfusions (7%); erythropoietin-stimulating agent use was anecdotal (∼1%). Treatment rates for severe anemia were higher, but 43% of patients still failed to receive treatment. Developing anemia was associated with a higher risk of MACE and death. CONCLUSION: Anemia was common and associated with adverse outcomes among patients with CKD stages 3-5 managed in primary care. Iron stores were infrequently tested, and a large proportion of patients with anemia remained untreated/under-recognized.

Discordances Between Creatinine- and Cystatin C-Based Estimated GFR and Adverse Clinical Outcomes in Routine Clinical Practice.

RATIONALE & OBJECTIVE: Cystatin C is recommended for measuring estimated glomerular filtration rate (eGFR) when estimates based on creatinine (eGFRcr) are not thought to be accurate enough for clinical decision making. While global adoption is slow, routine cystatin C testing in Sweden has been available for over a decade, providing real-world evidence about the magnitude of differences between eGFRcys and eGFRcr and their association with clinical outcomes. STUDY DESIGN: Observational study. SETTING & PARTICIPANTS: 158,601 adults (48% women; mean age 62 years, eGFRcr 80, and eGFRcys 73mL/min/1.73/m2) undergoing testing for creatinine and cystatin C on the same day in connection with a health care encounter during 2010-2018 in Stockholm, Sweden. EXPOSURE: Percentage difference of eGFRcys minus eGFRcr (eGFRdiff). OUTCOME: Kidney failure with replacement therapy (KFRT), acute kidney injury (AKI), atherosclerotic cardiovascular disease (ASCVD), heart failure, and death. ANALYTICAL APPROACH: Multivariable Cox proportional hazards regression. RESULTS: Discordances between eGFRcr and eGFRcys were common, with eGFRcys being lower than eGFRcr (negative eGFRdiff) in most cases (65%). Patients with larger negative eGFRdiff were older, more often female, with higher eGFRcr and albuminuria, and more comorbid conditions. Compared with patients with similar eGFRcys and eGFRcr, the lowest quartile (eGFRcys > 27% lower than eGFRcr) had the higher HR of all study outcomes: AKI, 2.6 (95% CI, 2.4-2.9); KFRT, 1.4 (95% CI, 1.2-1.6); ASCVD, 1.4 (95% CI, 1.3-1.5); heart failure, 2.0 (95% CI, 1.9-2.2); and all-cause death, 2.6 (95% CI, 2.5-2.7). Conversely, patients in the highest quartile (positive eGFRdiff) were at lower risk. LIMITATIONS: Observational study, lack of information on indications for cystatin C testing. CONCLUSIONS: Cystatin C testing in routine care shows that many patients have a lower eGFRcys than eGFRcr, and these patients have a higher risk of multiple adverse outcomes. PLAIN-LANGUAGE SUMMARY: Clinicians require guidance when there are discrepancies between the estimated glomerular filtration rate based on creatinine (eGFRcr) and based on cystatin C (eGFRcys) in the same individual. Routine cystatin C testing in Sweden for over a decade permits exploration of how common and large these discrepancies are, and their associations with adverse clinical outcomes. In this observational study, we found that discordances between eGFRcys and eGFRcr are common, and 1 in 4 patients tested had an eGFRcys > 28% lower than their eGFRcr. We also show that an eGFRcys that is lower than the eGFRcr consistently identifies patients at higher risk of adverse outcomes, including cardiovascular events, kidney replacement therapy, acute kidney injury, and death.

Interleukin-6-to-Albumin Ratio as a Superior Predictor of Mortality in End-Stage Kidney Disease Patients.

INTRODUCTION: In patients with chronic kidney disease (CKD), high interleukin-6 (IL-6) and low albumin circulating concentrations are associated with worse outcomes. We examined the IL-6-to-albumin ratio (IAR) as a predictor of risk of death in incident dialysis patients. METHODS: In 428 incident dialysis patients (median age 56 years, 62% men, 31% diabetes mellitus, 38% cardiovascular disease [CVD]), plasma IL-6 and albumin were measured at baseline to calculate IAR. We compared the discrimination of IAR with other risk factors for predicting 60-month mortality using receiver operating characteristic curve (ROC) and analyzed the association of IAR with mortality using Cox regression analysis. We divided patients into IAR tertiles and analyzed: (1) cumulative incidence of mortality and the association of IAR with mortality risk in Fine-Gray analysis, taking kidney transplantation as competing risk and (2) the restricted mean survival time (RMST) to 60-month mortality and differences of RMST (∆RMST) between IAR tertiles to describe quantitative differences of survival time. RESULTS: For all-cause mortality, the area under the ROC curve (AUC) for IAR was 0.700, which was greater than for IL-6 and albumin separately, while for CV mortality, the AUC for IAR (0.658) showed negligible improvement over IL-6 and albumin separately. In Cox regression analysis, IAR was significantly associated with all-cause mortality but not with CV mortality. Both high versus low and middle versus low tertiles of IAR associated with higher risk of all-cause mortality, subdistribution hazard ratio of 2.22 (95% CI 1.40-3.52) and 1.85 (95% CI 1.16-2.95), respectively, after adjusting for age, sex, diabetes mellitus, CVD, smoking, and estimated glomerular filtration rate. ∆RMST at 60 months showed significantly shorter survival time in middle and high IAR tertiles compared with low IAR tertile for all-cause mortality. CONCLUSIONS: Higher IAR was independently associated with significantly higher all-cause mortality risk in incident dialysis patients. These results suggest that IAR may provide useful prognostic information in patients with CKD.

Blood-Brain Barrier Biomarkers before and after Kidney Transplantation.

Kidney transplantation (KT) may improve the neurological status of chronic kidney disease (CKD) patients, reflected by the altered levels of circulating BBB-specific biomarkers. This study compares the levels of neuron specific enolase (NSE), brain-derived neurotrophic factor (BDNF), neurofilament light chain (NfL), and circulating plasma extracellular vesicles (EVs) in kidney-failure patients before KT and at a two-year follow up. Using ELISA, NSE, BDNF, and NfL levels were measured in the plasma of 74 living-donor KT patients. Plasma EVs were isolated with ultracentrifugation, and characterized for concentration/size and surface protein expression using flow cytometry from a subset of 25 patients. Lower NSE levels, and higher BDNF and NfL were observed at the two-year follow-up compared to the baseline (p < 0.05). Male patients had significantly higher BDNF levels compared to those of females. BBB biomarkers correlated with the baseline lipid profile and with glucose, vitamin D, and inflammation markers after KT. BBB surrogate marker changes in the microcirculation of early vascular aging phenotype patients with calcification and/or fibrosis were observed only in NSE and BDNF. CD31+ microparticles from endothelial cells expressing inflammatory markers such as CD40 and integrins were significantly reduced after KT. KT may, thus, improve the neurological status of CKD patients, as reflected by changes in BBB-specific biomarkers.