Variability of laboratory parameters is associated with frailty markers and predicts non-cardiac mortality in hemodialysis patients

The Surprise Question in Hemodialysis, Frailty, Nutrition, Patient-reported Quality of Life, and All-Cause Mortality: The Osaka Dialysis Complication Study (ODCS)

Rationale & Objective

A response "no" (SQ-No) to the surprise question (SQ) of whether a clinician would be surprised if a dialysis patient died in the next 6 months is associated with a higher risk of all-cause death. It is uncertain what domains are intuitively assessed with the SQ. We hypothesized that the SQ would assess the patient's frailty, malnutrition, or patient-perceived health-related quality of life in a cohort of patients on maintenance hemodialysis.

Study Design

Cohort study.

Setting & Participants

A multicenter study including 994 patients on maintenance hemodialysis in Japan.

Predictors

(1) SQ answered by nurses; (2) frailty by modified Cardiovascular Health Study criteria; (3) malnutrition as evaluated by Geriatric Nutritional Risk Index (GNRI); and (4) patient-perceived health-related quality of life examined by the 36-Item Short Form Health Survey (SF-36) physical component summary (PCS).

Outcomes

All-cause mortality.

Analytical Approach

Cox proportional hazard models.

Results

Median age and dialysis vintage were 66 and 5.9 years, respectively, 35.8% were women, and 39.6% had diabetic kidney disease. The prevalence of SQ-No and frailty was 19.7% and 45.9%. Median GNRI and SF-36 PCS scores were 96.3 and 36.9, respectively. During the 5-year follow-up, 247 patients died. SQ-No, being frail, low GNRI, and low SF-36 PCS were each significant predictors of a higher risk for mortality independent of potential confounders. SQ-No remained a significant predictor after further adjustment for frailty or GNRI, but SQ-No was no longer significant when adjusted for SF-36 PCS.

Limitations

We did not assess the agreement of responses to the SQ between different raters.

Conclusions

The predictive ability of the SQ was closely related to SF-36 PCS in hemodialysis patients. Nurses' answer to the SQ appears to assess the physical domain of patient-perceived health-related quality of life rather than objectively assessed frailty or malnutrition.

Visit-to-visit variability in multiple biological measurements and cognitive performance and risk of cardiovascular disease: A cohort study

Background

Visit-to-visit variability in single biological measurements has been associated with cognitive decline and an elevated risk of cardiovascular diseases (CVD). However, the effect of visit-to-visit variability in multiple biological measures is underexplored. We investigated the effect of visit-to-visit variability in blood pressure (BP), heart rate (HR), weight, fasting plasma glucose, cholesterol, and triglycerides on cognitive performance and CVD.

Methods

Data on BP, HR, weight, glucose, cholesterol, and triglycerides from study visits in the Outcome Reduction with Initial Glargine Intervention (ORIGIN) trial were used to estimate the association between visit-to-visit variability, cognitive performance (Mini Mental State Examination (MMSE) score) and CVD (non-fatal stroke, non-fatal myocardial infarction, or cardiovascular death). Visit-to-visit variation for each measurement was estimated by calculating each individuals visit-to-visit standard deviation for that measurement. Participants whose standard deviation was in the highest quarter were classified as having high variation. Participants were grouped into those having 0, 1, 2, 3, or ≥ 4 high variation measurements. Regression and survival models were used to estimate the association between biological measures with MMSE and CVD with adjustment for confounders and mean measurement value.

Results

After adjustment for covariates, higher visit-to-visit variability in BP, HR, weight, and FPG were associated with poorer MMSE and a higher risk of CVD. Effect sizes did not vary greatly by measurement. The effects of high visit-to-visit variability were additive; compared to participants who had no measurements with high visit-to-visit variability, those who had high visit-to-visit variability in ≥4 measurements had poorer MMSE scores (-0.63 (95 % CI -0.96 to -0·31). Participants with ≥4 measurements with high visit-to-visit variability compared to participants with none had higher risk of CVD (hazard ratio 2.46 (95 % CI 1.63 to 3.70).

Conclusion

Visit-to-visit variability in several measurements were associated with cumulatively poorer cognitive performance and a greater risk of CVD.

Association between annual variability of potassium levels and prognosis in patients undergoing hemodialysis

BACKGROUND

Hyperkalemia and hypokalemia are associated with mortality in patients undergoing hemodialysis. However, there are few reports on the association between potassium level fluctuations and mortality. We retrospectively investigated the association between serum potassium level variability and mortality in patients undergoing hemodialysis.

METHODS

This study was conducted at a single center. Variability in serum potassium levels was evaluated using the standard deviation of potassium level from July 2011 to June 2012, and its association with prognosis was examined by following up the patients for 5 years. Serum potassium variability was assessed as the coefficient of variation, and the statistical analysis was performed after log transformation.

RESULTS

Among 302 patients (mean age 64.9 ± 13.3; 57.9% male; and median dialysis vintage 70.5 months [interquartile range, IQR 34-138.3]), 135 died during the observation period (median observation period 5.0 years [2.3-5.0]). Although the mean potassium level was not associated with prognosis, serum potassium level variability was associated with prognosis, even after adjustments for confounding factors such as age and dialysis time (hazard ratio: 6.93, 95% confidence interval [Cl] 1.98-25.00, p = 0.001). After the adjustments, the coefficient of variation of potassium level in the highest tertile (T3) showed a higher relative risk for prognosis than that in T1 (relative risk: 1.98, 95% CI 1.19-3.29, p = 0.01).

CONCLUSIONS

Variability in serum potassium levels was associated with mortality in patients undergoing hemodialysis. Careful monitoring of potassium levels and their fluctuations is necessary for this patient population.

Effects of Niaoduqing granules on inflammatory response of diabetic kidney disease: A meta‑analysis

Diabetic kidney disease (DKD) is one of the most severe chronic microvascular complications of diabetes and the leading cause of end-stage kidney disease worldwide. The mechanism of inflammation underlying DKD has been attracting attention over recent years, but effective therapeutic strategies have remained elusive. Niaoduqing (NDQ) granules are one of the most commonly used drugs for the treatment of DKD in China, and it has therapeutic effects against inflammation in DKD. Therefore, the aim of the present analysis was to evaluate the inflammatory response outcomes and safety of NDQ granules for the treatment of DKD. The following databases were searched from their inception to 31st of May 2023 to obtain published accounts of relevant randomized controlled trials: China National Knowledge Infrastructure, China Science and Technology Journal, Wanfang, The Chinese Biomedicine, PubMed, Web of Science and Cochrane Library. The 'risk of bias' evaluation tool produced by the Cochrane Collaboration Handbook was used for evaluating the quality, whereas Revman software (version 5.3) was used for meta-analysis. In total, 16 studies were included into the present study according to criteria, with a total of 1,526 patients. Compared with those in the control group, the results of the meta-analysis revealed that the combination of conventional treatment and NDQ granules may further decrease C-reactive protein [standardized mean difference (SMD), -1.33; 95% confidence interval (CI), -1.76, -0.91; P<0.00001], TNF-α (SMD, -1.90; 95% CI, -2.35,-1.45; P<0.00001) and IL-6 (SMD, -1.72; 95% CI, -2.52,-0.91; P<0.0001) levels, whilst increasing the clinical effective rate (risk ratio, 1.22; 95% CI, 1.14,1.29; P<0.00001), in patients with DKD. In terms of safety, a total of 34 and 39 patients included in the intervention and in the control group, respectively, developed adverse reactions. Results from the present analysis suggest that NDQ granules may be beneficial in suppressing inflammation caused by DKD when used in combination with conventional treatment, potentially guiding future directions in clinical practice. However, further high-quality studies are needed to confirm the anti-inflammation response in the future.

Variability of Serum Phosphate in Incident Hemodialysis Patients: Association with All-Cause Mortality

Key Points

An increase in serum phosphate variability is an independent risk factor of mortality. The effects of a positive directional range (DR) is most pronounced in patients with high serum phosphate levels whereas the effects of a negative DR is most pronounced in patients with low serum phosphate and/or serum albumin.

Background

In maintenance hemodialysis (HD) patients, previous studies have shown that serum phosphate levels have a bidirectional relation to outcome. Less is known about the relation between temporal dynamics of serum phosphate in relation to outcome. We aimed to further explore the relation between serum phosphate variability and all-cause mortality.

Methods

All adult incident HD patients treated in US Fresenius Kidney Care clinics between January 2010 and October 2018 were included. Baseline period was defined as 6 months after initiation of HD and months 7–18 as follow-up period. All-cause mortality was recorded during the follow-up period. The primary metric of variability used was directional range (DR) that is the difference between the largest and smallest values within a time period; DR was positive when the smallest value preceded the largest and negative otherwise. Cox proportional hazards models with spline terms were applied to explore the association between phosphate, DR, and all-cause mortality. In addition, tensor product smoothing splines were computed to further elucidate the interactions of phosphate, DR, and all-cause mortality.

Results

We included 302,613 patients. Baseline phosphate was 5.1±1.2 mg/dl, and mean DR was +0.6±3.3 mg/dl. Across different levels of phosphate, higher levels of DR of phosphate were associated with higher risk of all-cause mortality. In patients with lower levels of phosphate and serum albumin, the effect of a negative DR was most pronounced, whereas in patients with higher phosphate levels, a positive DR was related to increased mortality.

Conclusions

Higher variability of serum phosphate is related to mortality at all levels of phosphate, especially in lower levels with a negative DR and in low serum albumin levels. This could possibly reflect dietary intake in patients who are already inflamed or malnourished, where a further reduction in serum phosphate should prompt for nutritional evaluation.

Intercorrelated variability in blood and hemodynamic biomarkers reveals physiological network in hemodialysis patients

Increased intra-individual variability of a variety of biomarkers is generally associated with poor health and reflects physiological dysregulation. Correlations among these biomarker variabilities should then represent interactions among heterogeneous biomarker regulatory systems. Herein, in an attempt to elucidate the network structure of physiological systems, we probed the inter-variability correlations of 22 biomarkers. Time series data on 19 blood-based and 3 hemodynamic biomarkers were collected over a one-year period for 334 hemodialysis patients, and their variabilities were evaluated by coefficients of variation. The network diagram exhibited six clusters in the physiological systems, corresponding to the regulatory domains for metabolism, inflammation, circulation, liver, salt, and protein. These domains were captured as latent factors in exploratory and confirmatory factor analyses (CFA). The 6-factor CFA model indicates that dysregulation in each of the domains manifests itself as increased variability in a specific set of biomarkers. Comparison of a diabetic and non-diabetic group within the cohort by multi-group CFA revealed that the diabetic cohort showed reduced capacities in the metabolism and salt domains and higher variabilities of the biomarkers belonging to these domains. The variability-based network analysis visualizes the concept of homeostasis and could be a valuable tool for exploring both healthy and pathological conditions.

Association of single and serial measures of serum phosphorus with adverse outcomes in patients on peritoneal dialysis: results from the international PDOPPS

BACKGROUND

While high serum phosphorus levels have been related to adverse outcomes in hemodialysis patients, further investigation is warranted in persons receiving peritoneal dialysis (PD).

METHODS

Longitudinal data (2014-17) from the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS), a prospective cohort study, were used to examine associations of serum phosphorus with all-cause mortality and major adverse cardiovascular events via Cox regression adjusted for confounders. Serum phosphorus levels were parameterized by four methods: (i) baseline serum phosphorus; (ii) mean 6-month serum phosphorus; (iii) number of months with serum phosphorus >4.5 mg/dL; and (iv) mean area-under-the-curve of 6-month serum phosphorus control.

RESULTS

The study included 5847 PD patients from seven countries; 9% of patients had baseline serum phosphorus <3.5 mg/dL, 24% had serum phosphorus ≥3.5 to ≤4.5 mg/dL, 30% had serum phosphorus >4.5 to <5.5 mg/dL, 20% had serum phosphorus ≥5.5 to <6.5 mg/dL, and 17% had serum phosphorus ≥6.5 mg/dL. Compared with patients with baseline serum phosphorus ≥3.5 to ≤4.5 mg/dL, the adjusted all-cause mortality hazard ratio (HR) was 1.19 (0.92,1.53) for patients with baseline serum phosphorus ≥5.5 to <6.5 mg/dL and HR was 1.53 (1.14,2.05) for serum phosphorus ≥6.5 mg/dL. Associations between serum phosphorus measurements over 6 months and clinical outcomes were even stronger than for a single measurement.

CONCLUSIONS

Serum phosphorus >5.5 mg/dL was highly prevalent (37%) in PD patients, and higher serum phosphorus levels were a strong predictor of morbidity and death, particularly when considering serial phosphorus measurements. This highlights the need for improved treatment strategies in this population. Serial serum phosphorus measurements should be considered when assessing patients' risks of adverse outcomes.

An effective model for predicting serum albumin level in hemodialysis patients

Patients on hemodialysis (HD) are known to be at an increased risk of mortality. Hypoalbuminemia is one of the most important risk factors of death in HD patients, and is an independent risk factor for all-cause mortality that is associated with cardiac death, infection, and Protein-Energy Wasting (PEW). It is a clinical challenge to elevate serum albumin level. In addition, predicting trends in serum albumin level is effective for personalized treatment of hypoalbuminemia. In this study, we analyzed a total of 3069 records collected from 314 HD patients using a machine learning method that is based on an improved binary mutant quantum grey wolf optimizer (MQGWO) combined with Fuzzy K-Nearest Neighbor (FKNN). The performance of the proposed MQGWO method was evaluated using a series of experiments including global optimization experiments, feature selection experiments on open data sets, and prediction experiments on an HD dataset. The experimental results showed that the most critical relevant indicators such as age, presence or absence of diabetes, dialysis vintage, and baseline albumin can be identified by feature selection. Remarkably, the accuracy and the specificity of the method were 98.39% and 96.77%, respectively, demonstrating that this model has great potential to be used for detecting serum albumin level trends in HD patients.

Proactive Measures to Combat a SARS-CoV-2 Transmission Among High Risk Patients and Health Care Workers in an Outpatient Dialysis Facility

Background: End-stage-renal-failure (ESRF) patients attending clustered out-patient dialysis are susceptible to SARS-CoV-2 infection. Comorbidities render them vulnerable to severe COVID-19. Although preventative and mitigation strategies are recommended, the effect of these are unknown. A period of “potential-high-infectivity” results if a health-care-worker (HCWs) or a patient becomes infected.

Aim: We describe and analyze early, universal SARS-CoV-2 real time reverse transcription polymerase chain reaction (RT-PCR) tests, biomarker monitoring and SARS-CoV-2 preventative strategies, in a single dialysis center, after a positive patient was identified.

Methodology: The setting was a single outpatient dialysis center in Johannesburg, South Africa which had already implemented preventative strategies. We describe the management of 57 patients and 11 HCWs, after one of the patients tested positive for SARS-CoV-2. All individuals were subjected to RT-PCR tests and biomarkers (Neutrophil-Lymphocyte Ratio, C-reactive protein, and D-Dimer) within 72 h (initial-tests). Individuals with initial negative RT-PCR and abnormal biomarkers (one or more) were subjected to repeat RT-PCR and biomarkers (retest subgroup) during the second week. Additional stringent measures (awareness of viral transmission, dialysis distancing and screening) were implemented during the period of “potential high infectivity.” The patient retest subgroup also underwent clustered dialysis until retest results became available.

Results: A second positive-patient was identified as a result of early universal RT-PCR tests. In the two positive-patients, biomarker improvement coincided with RT-PCR negative tests. We identified 13 individuals for retesting. None of these retested individuals tested positive for SARS-CoV-2 and there was no deterioration in median biomarker values between initial and retests. Collectively, none of the negative individuals developed COVID-19 symptoms during the period “potential high infectivity.”

Conclusion: A SARS-CoV-2 outbreak may necessitate additional proactive steps to counteract spread of infection. This includes early universal RT-PCR testing and creating further awareness of the risk of transmission and modifying preventative strategies. Abnormal biomarkers may be poorly predictive of SARS-CoV-2 infection in ESRF patients due to underlying illnesses. Observing dynamic changes in biomarkers in RT-PCR positive and negative-patients may provide insights into general state of health.

Efficacy of blood urea nitrogen and the neutrophil-to-lymphocyte ratio as predictors of mortality among elderly patients with genitourinary tract infections: A retrospective multicentre study

OBJECTIVES

To investigate whether initial blood urea nitrogen (BUN) and the neutrophil-to-lymphocyte ratio (NLR) in the emergency department (ED) are associated with mortality in elderly patients with genitourinary tract infections.

METHODS

A total of 541 patients with genitourinary tract infections in 5 EDs between November 2016 and February 2017 were included and retrospectively reviewed. We assessed age, sex, comorbidities, vital signs, and initial laboratory results, including BUN, NLR and the SOFA criteria. The primary outcome was all-cause in-hospital mortality.

RESULTS

The nonsurvivor group included 32 (5.9%) elderly patients, and the mean arterial pressure (MAP), NLR and BUN were significantly higher in this group than in the survivor group (p < 0.001, p = 0.003, p < 0.001). In multivariate analysis, MAP <70 mmHg, NLR ≥23.8 and BUN >28 mg/dl were shown to be independent risk factors for in-hospital mortality (OR 3.62, OR 2.51, OR 2.76: p = 0.002, p = 0.033, p = 0.038, respectively). Additionally, NLR ≥23.8 and BUN >28 were shown to be independent risk factors for mortality in admitted elderly with complicated UTI (p = 0.030, p = 0.035). When BUN and NLR were combined with MAP, the area under the ROC curve (AUROC) value was 0.807 (0.771-0.839) for the prediction of mortality, the sensitivity was 87.5% (95% CI 71.0-96.5), and the specificity was 61.3% (95% CI 56.9-65.5%).

CONCLUSION

The initial BUN and NLR values with the MAP were good predictors associated with all-cause in-hospital mortality among elderly genitourinary tract infections visiting the ED.

Association of Visit-to-Visit Variability in Kidney Function and Serum Electrolyte Indexes With Risk of Adverse Clinical Outcomes Among Patients With Heart Failure With Preserved Ejection Fraction

Importance

Although kidney dysfunction and abnormalities in serum electrolyte levels are associated with poor clinical outcomes in patients with heart failure with preserved ejection fraction (HFpEF), the association of visit-to-visit variability in such laboratory measures with long-term outcomes is unclear.

Objective

To evaluate the associations of visit-to-visit variability in indexes of kidney function (creatinine and blood urea nitrogen [BUN] levels) and serum electrolyte (sodium, chloride, and potassium) with the risk of adverse clinical outcomes among patients with chronic, stable HFpEF.

Design, Setting, and Participants

This cohort analysis used data from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial. All participants with 3 or more serial laboratory measurements who were event free within the first 4 months of enrollment were included. Data were analyzed from March 1, 2019, to January 31, 2020.

Main Outcomes and Measures

Adjusted associations between indexes of variability in serum laboratory measurements during the first 4 months of follow-up and risk of the primary composite outcome (a composite of aborted cardiac arrest, hospitalization for heart failure, or cardiovascular death) and all-cause mortality were assessed using Cox proportional hazards regression models.

Results

Of the 3445 patients enrolled in the TOPCAT trial (mean [SD] age, 68-69 [10] years; 49.7%-51.5% female), 2479 (BUN) to 3195 (potassium) were analyzed, depending on availability of serial measurements. Participants with higher laboratory variability in kidney function parameters were older, had more comorbidities, and had more severe symptoms of HFpEF. Higher visit-to-visit variability in BUN (hazard ratio [HR] per 1-SD higher average successive variability [ASV], 1.21; 95% CI, 1.10-1.33) and creatinine (HR per 1-SD higher ASV, 1.13; 95% CI, 1.04-1.22) were independently associated with a higher risk of the primary composite outcome as well as mortality independent of other baseline confounders, changes in kidney function, changes in medication dosages, and variability in other cardiometabolic parameters (systolic blood pressure and body mass index). The higher risk associated with greater variability in kidney function was consistent across subgroups of patients stratified by the presence of chronic kidney disease (CKD) at baseline (CKD: HR per 1-SD higher ASV, 1.39; 95% CI, 1.16-1.67 and no CKD: HR per 1-SD higher ASV, 1.13; 95% CI, 1.01-1.27), among placebo and spironolactone treatment arms separately (spironolactone arm: 1.30; 95% CI, 1.03-1.65 and placebo arm: HR per 1-SD higher ASV, 1.27; 95% CI, 1.04-1.56). Among serum electrolytes, variability in sodium and potassium measures were also significantly associated with a higher risk of primary composite events (sodium: HR per 1-SD higher ASV, 1.14; 95% CI, 1.01-1.30 and potassium: HR per 1-SD higher ASV, 1.21; 95% CI, 1.02-1.44).

Conclusions and Relevance

In HFpEF, visit-to-visit variability in laboratory indexes of kidney function and serum electrolytes is common and independently associated with worse long-term clinical outcomes.

Elevated Red Cell Distribution Width Is Independently Associated With a Higher Frailty Risk Among 2,932 Community-Dwelling Older Adults

Background: Older adults are at an increased risk of frailty, but laboratory surrogates for identifying frailty in this population remain controversial and clinicians frequently encounter difficulty during frailty screening. We examined whether having a high red cell distribution width (RDW) was associated with an increased probability of frailty in older adults.

Methods: We prospectively included community-dwelling older adults between 2013 and 2016 from a single institute, with their clinical features/laboratory parameters documented. We used the Study of Osteoporotic Fractures index (malnutrition, poor physical performance, and fatigue) to delineate frailty, and harnessed multiple logistic regression to investigate whether having a high RDW (≥ 15.7%) was associated with an increased risk of having frailty among these participants.

Results: A total of 2,932 older adults (mean 73.5 ± 6.7 years; 44.6% male) were included, among whom 113 (3.9%) and 76 (2.6%) had a high RDW and presented frailty, respectively. Older adults with a high RDW were more likely to be frail (p = 0.002) and had more positive SOF items than those with normal RDW levels (p = 0.013). Those with a high RDW exhibited a significantly higher risk of having frailty (odds ratio [OR] 2.689, 95% confidence interval [CI] 1.184–6.109) compared to those without. Sensitivity analyses using RDW as a continuous variable similarly showed that RDW levels were positively associated with frailty risk (OR 1.223 per 1% RDW higher).

Conclusions: In older adults, higher RDW can be regarded as a frailty indicator, and the readiness in RDW assessment supports its screening utility.

Markers of protein-energy wasting and physical performance in haemodialysis patients: A cross-sectional study

Background

Physical impairments are common in uraemia, as reflected by the high risk of falls of haemodialysis (HD) patients. Furthermore, these patients often suffer from malnutrition.

Objective

Up to now, it is unknown which aspects of physical performance are predominantly driven by malnutrition in HD patients. As this answer could steer different interventions, the aim of this study was to evaluate the cross-sectional relationship between nutritional status, muscle strength, exercise capacity and the risk of falls.

Methods

This study recruited HD patients between December 2016 and March 2018 from two hospital-based and five satellite dialysis units (registration number on clinicaltrial.gov: NCT03910426). The mini-nutritional assessment scale as well as objective measures of protein-energy wasting were obtained (total iron-binding capacity, total protein levels, and CRP). Physical assessment included muscle strength (quadriceps, handgrip force, and sit-to-stand test), exercise capacity (six-minute walking test) and the risk of falls (Tinetti, FICSIT, and dialysis fall index). Their interrelationship was analysed by ridge regression models.

Results

Out of 113 HD patients (mean age 67 years ± 16.1, 57.5% male) 36.3% were malnourished according to the mini-nutritional assessment scale and a majority had impaired quadriceps force (86.7%), six-minute walking test (92%), and an increased risk of falls (73.5%). Total protein and CRP levels were identified as relevant nutritional factors in the association with physical performance. Nutritional parameters explained 9.2% of the variance in the risk of falls and 7.6% of the variance in exercise capacity. No conclusive association was found between nutritional status and muscle strength.

Conclusion

Protein-energy wasting is a determinant of the risk of falls and exercise capacity in patients on HD. The association between malnutrition and muscle weakness remains inconclusive.

The Impact of CKD Anaemia on Patients: Incidence, Risk Factors, and Clinical Outcomes-A Systematic Literature Review

Anaemia is a common consequence of chronic kidney disease (CKD); however, the risk factors for its development and its impact on outcomes have not been well synthesised. Therefore, we undertook a systematic review to fully characterise the risk factors associated with the presence of anaemia in patients with CKD and a contemporary synthesis of the risks of adverse outcomes in patients with CKD and anaemia. We searched MEDLINE, EMBASE, and the Cochrane Library from 2002 until 2018 for studies reporting the incidence or prevalence of anaemia and associated risk factors and/or associations between haemoglobin (Hb) or anaemia and mortality, major adverse cardiac events (MACE), hospitalisation, or CKD progression in adult patients with CKD. Extracted data were summarised as risk factors related to the incidence or prevalence of anaemia or the risk (hazard ratio (HR)) of outcome by Hb level (<10, 10-12, >12 g/dL) in patients not on dialysis and in those receiving dialysis. 191 studies met the predefined inclusion criteria. The risk factor most associated with the prevalence of anaemia was CKD stage, followed by age and sex. Mean HRs (95% CI) for all-cause mortality in patients with CKD on dialysis with Hb <10, 10-12, and >12 g/dL were 1.56 (1.43-1.71), 1.17 (1.09-1.26), and 0.91 (0.87-0.96), respectively. Similar patterns were observed for nondialysis patients and for the risks of hospitalisation, MACE, and CKD progression. This is the first known systematic review to quantify the risk of adverse clinical outcomes based on Hb level in patients with CKD. Anaemia was consistently associated with greater mortality, hospitalisation, MACE, and CKD progression in patients with CKD, and risk increased with anaemia severity. Effective treatments that not only treat the anaemia but also reduce the risk of adverse clinical outcomes are essential to help reduce the burden of anaemia and its management in CKD.

Estimation of homeostatic dysregulation and frailty using biomarker variability: a principal component analysis of hemodialysis patients

Increased intraindividual variability in several biological parameters is associated with aspects of frailty and may reflect impaired physiological regulation. As frailty involves a cumulative decline in multiple physiological systems, we aimed to estimate the overall regulatory capacity by applying a principal component analysis to such variability. The variability of 20 blood-based parameters was evaluated as the log-transformed coefficient of variation (LCV) for one year’s worth of data from 580 hemodialysis patients. All the LCVs were positively correlated with each other and shared common characteristics. In a principal component analysis of 19 LCVs, the first principal component (PC1) explained 27.7% of the total variance, and the PC1 score exhibited consistent correlations with diverse negative health indicators, including diabetes, hypoalbuminemia, hyponatremia, and relative hypocreatininemia. The relationship between the PC1 score and frailty was subsequently examined in a subset of the subjects. The PC1 score was associated with the prevalence of frailty and was an independent predictor for frailty (odds ratio per SD: 2.31, P = 0.01) using a multivariate logistic regression model, which showed good discrimination (c-statistic: 0.85). Therefore, the PC1 score represents principal information shared by biomarker variabilities and is a reasonable measure of homeostatic dysregulation and frailty.

Predictive Model for Mortality Risk Including the Wound, Ischemia, Foot Infection Classification in Patients Undergoing Revascularization for Critical Limb Ischemia

Background:

The aim of this study was to develop a predictive model for mortality risk based on preoperative risk factors, including the Wound, Ischemia, Foot Infection (WIfI) classification, in patients undergoing revascularization for critical limb ischemia.

Methods:

We analyzed a database of the Surgical reconstruction versus Peripheral Intervention in Patients With Critical Limb Ischemia registry, a multicenter, prospective, observational study that included 520 critical limb ischemia patients (192 surgical and 328 endovascular patients).

Results:

Multivariate Cox regression analysis identified old age, impaired mobility, low body mass index, renal failure, heart failure, and high WIfI grade as independent risk factors for all-cause mortality (all P <0.05). The risk score comprising these risk factors discriminated the mortality risk well; the 2-year survival rate was >90% in the first quantile of the risk score and ≈20% in the fifth quantile. The area under the time-dependent receiver operating characteristics curve was 0.829 for thirty-day mortality and 0.811 for 2-year mortality. Adding more detailed preoperative information to the predictive model revealed that cystatin C-based estimated glomerular filtration rate, left ventricular ejection fraction, and cholinesterase levels were additional independent risk factors, but the predictive accuracy of the model was not significantly improved, according to the time-dependent receiver operating characteristics curve and net reclassification improvement.

Conclusions:

The current study developed a risk score for mortality using preoperative risk factors, including the WIfI classification, in critical limb ischemia patients undergoing revascularization.

BUN as an Independent Predictor of Post-Hospital-Discharge Mortality among Older Veterans

BACKGROUND/OBJECTIVES

An elevated blood urea nitrogen (BUN) in known to be an important prognostic indicator in patients with end-stage heart or kidney disease or certain other life-threatening illnesses. However, it is less certain as to whether an elevated BUN is an independent predictor of long-term mortality risk in less seriously ill patients. To address this issue, we examined the relationship between BUN and long-term mortality after adjusting for potential confounders and other indicators of health status/disease severity, in a select population of older medically stable Veterans.

DESIGN

Long-term prospective cohort study.

SETTING

Outpatient follow-up of patients discharged from a recuperative care and rehabilitation unit (RCRU) of a Department of Veterans Affairs Community Living Center.

PARTICIPANTS

383 older Veterans (mean age = 78.6±7.6 years, 98% male, and 87% white) discharged alive and in stable medical condition.

MEASUREMENTS

At discharge, each subject completed a comprehensive assessment and was then monitored as an outpatient for up to 9.3 years. Associations between blood urea nitrogen at RCRU discharge and mortality were identified utilizing Cox proportional hazards (PH) regression analyses adjusting for conditions known to confound this relationship.

RESULTS

Within the follow-up period, 255 subjects (67%) died. In the unadjusted Cox PH model, a BUN ≥ 30 mg/dL was associated with a nearly 2-fold increased risk of mortality (hazard ratio 1.90, 95%CI 1.41 - 2.56). The association between BUN and long-term mortality remained highly significant after adjusting for potential confounders (hazard ratio 1.78, 95%CI 1.29 - 2.44).

CONCLUSION

Our findings support BUN levels as an independent predictor of long-term mortality in older, medically stable Veterans. An elevated BUN may be reflective of global health status rather than solely an indicator of the severity of acute illness or unstable chronic disease.

Spontaneous variability of pre-dialysis concentrations of uremic toxins over time in stable hemodialysis patients

Background and aim

Numerous outcome studies and interventional trials in hemodialysis (HD) patients are based on uremic toxin concentrations determined at one single or a limited number of time points. The reliability of these studies however entirely depends on how representative these cross-sectional concentrations are. We therefore investigated the variability of predialysis concentrations of uremic toxins over time.

Methods

Prospectively collected predialysis serum samples of the midweek session of week 0, 1, 2, 3, 4, 8, 12, and 16 were analyzed for a panel of uremic toxins in stable chronic HD patients (N = 18) while maintaining dialyzer type and dialysis mode during the study period.

Results

Concentrations of the analyzed uremic toxins varied substantially between individuals, but also within stable HD patients (intra-patient variability). For urea, creatinine, beta-2-microglobulin, and some protein-bound uremic toxins, Intra-class Correlation Coefficient (ICC) was higher than 0.7. However, for phosphorus, uric acid, symmetric and asymmetric dimethylarginine, and the protein-bound toxins hippuric acid and indoxyl sulfate, ICC values were below 0.7, implying a concentration variability within the individual patient even exceeding 65% of the observed inter-patient variability.

Conclusion

Intra-patient variability may affect the interpretation of the association between a single concentration of certain uremic toxins and outcomes. When performing future outcome and interventional studies with uremic toxins other than described here, one should quantify their intra-patient variability and take into account that for solutes with a large intra-patient variability associations could be missed.

Aging and death-associated changes in serum albumin variability over the course of chronic hemodialysis treatment

Background

Several epidemiological studies have demonstrated associations between variability in a number of biological parameters and adverse outcomes. As the variability may reflect impaired homeostatic regulation, we assessed albumin variability over time in chronic hemodialysis (HD) patients.

Methods

Data from 1346 subjects who received chronic HD treatment from May 2001 to February 2015 were analyzed according to three phases of HD treatment: post-HD initiation, during maintenance HD treatment, and before death. The serum albumin values were grouped according to the time interval from HD initiation or death, and the yearly trends for both the albumin levels and the intra-individual albumin variability (quantified by the residual coefficient of variation: Alb-rCV) were examined. The HD initiation and death-associated changes were also analyzed using generalized additive mixed models. Furthermore, the long-term trend throughout the maintenance treatment period was evaluated separately using linear regression models.

Results

Albumin levels and variability showed distinctive changes during each of the 3 periods. After HD initiation, albumin variability decreased and reached a nadir within a year. During the subsequent maintenance treatment period (interquartile range = 5.2–11.0 years), the log Alb-rCV showed a significant upward trend (mean slope: 0.011 ± 0.035 /year), and its overall mean was -1.49 ± 0.08 (equivalent to an Alb-rCV of 3.22%). During the 1–2 years before death, this upward trend clearly accelerated, and the mean log Alb-rCV in the last year of life was -1.36 ± 0.17. The albumin levels and variability were negatively correlated with each other and exhibited exactly opposite movements throughout the course of chronic HD treatment. Different from the albumin levels, albumin variability was not dependent on chronological age but was independently associated with an individual’s aging and death process.

Conclusion

The observed upward trend in albumin variability seems to be consistent with a presumed aging-related decline in homeostatic capacity.

Physical function at the time of dialysis initiation is associated with subsequent mortality

BACKGROUND

In dialysis patients, physical function is associated with mortality. However, the association between physical function at the time of dialysis initiation and subsequent mortality remains unknown.

METHODS

A total of 1496 patients with chronic kidney disease who initiated dialysis at 17 centers participating in the Aichi Cohort Study of the Prognosis in Patients Newly Initiated into Dialysis, a multicenter prospective cohort study, were included. The patients were divided into the high (H)-, middle (M)-, and low (L)-score groups according to Barthel index (BI) at the time of dialysis initiation, and the all-cause, cardiovascular disease (CVD)-related, and infection-related mortality rates were compared. Moreover, factors affecting all-cause mortality were investigated. The effects of BI on mortality were assessed in the patients stratified by age, sex, and history of CVD or cerebral infarction.

RESULTS

A log-rank test for the Kaplan-Meier survival curve showed significant differences between the three groups in all-cause, CVD-related, and infection-related mortality rates (p < 0.001). Cox proportional hazard regression analysis with the step-wise method showed a significantly higher risk of all-cause mortality in the M and L groups than in the H group (M group: HR 1.612, 95 % CI 1.075-2.417; L group: HR 1.994, 95 % CI 1.468-2.709). Regardless of the age categories and the history of CVD, the risk of all-cause mortality was significantly higher in the L group than in the H group.

CONCLUSION

Physical function assessed by BI at the time of dialysis initiation was found to be associated with subsequent mortality.