Clinical and predictive value of simplified creatinine index used as muscle mass surrogate in end-stage kidney disease haemodialysis patients-results from the international MONitoring Dialysis Outcome initiative

Modified creatinine index for predicting prognosis in hemodialysis patients: a systematic review and meta-analysis

BACKGROUND

Currently, several studies have explored the association between the modified creatinine index (mCI) and prognosis in patients on hemodialysis (HD). However, some of their results are contradictory. Therefore, this study was conducted to comprehensively assess the role of mCI in predicting prognosis in HD patients through meta-analysis.

METHODS

We searched and screened literature from PubMed, Embase, Web of Science, and Cochrane databases from their establishment until March 2024. Relevant data were extracted. The statistical analysis was performed using Stata 15.0, RevMan 5.4, and Meta DiSc 1.4 software.

RESULTS

The results showed a positive association between mCI and nutritional status in HD patients (BMI r = 0.19, 95% CI: 0.1-0.28, p = .000; albumin r = 0.36, 95% CI: 0.33-0.39, p = .000; normalized protein catabolic rate (nPCR) r = 0.25, 95% CI: 0.13-0.38, p = .000). In addition, mCI in deceased HD patients was significantly lower than that in HD survivors (SMD = -0.94, 95% CI: -1.46 to -0.42, p = .000). A low mCI was associated with an increased risk of all-cause death in HD patients (HR = 1.95, 95% CI: 1.57-2.42, p = .000). In addition, a low mCI was significantly associated with decreased overall survival (OS) in HD patients (HR = 3.01, 95% CI: 2.44-3.70, p = .000). mCI showed moderate diagnostic accuracy for sarcopenia in both male and female HD patients (male AUC = 0.7891; female AUC = 0.759).

CONCLUSIONS

The mCI can be used as a prognostic marker for HD patients, and monitoring mCI may help to optimize the management of HD and improve overall prognosis in patients.

Osteocalcin and Chinese visceral adiposity index are associated with the risk of ASCVD and arterial stiffness in patients with T2DM

This study aims to discover the association between serum osteocalcin, the Chinese visceral adiposity index (CVAI), and atherosclerotic cardiovascular disease (ASCVD) risk, and their impact on arterial stiffness in T2DM patients. We included 639 T2DM patients aged 30 and older who received the assessment of ASCVD risk using the China-PAR equation, Osteocalcin and arterial stiffness in this cross-sectional study. We found that osteocalcin and CVAI as independent risk factors for both medium-high-risk ASCVD (osteocalcin: men, OR,0.96, 95% CI 0.92, 1.00; women, OR, 0.93, 95% CI 0.8, 1.08, respectively)(CVAI: men, OR,1.01,95% CI 1.00,1.02; women: OR, 1.08, 95% CI 1.02,1.14, respectively) and arterial stiffness (osteocalcin: men, OR, 0.98, 95% CI 0.94,1.01; women, OR, 0.98, 95% CI 0.90,1.06, respectively)(CVAI: men, OR,1.0, 95% CI 0.99,1.01; women, OR, 1.02, 95% CI 1.00,1.04, respectively) in both men and women patients with T2DM. Combining osteocalcin levels and CVAI improved the prediction accuracy of arterial stiffness in men patients with T2DM (difference of AUC(Model 4 vs. Model 1):1.5%, NRI: 0.06 [0.0,0.4]). All P-values were < 0.05. The results suggested that osteocalcin levels and CVAI are independent risk factors for ASCVD risk and arterial stiffness in T2DM. Combining osteocalcin and CVAI can enhance the early detection of atherosclerosis through male patients with T2DM.

Using a measurement type-independent metric to compare patterns of determinants between patient-reported versus performance-based physical function in hemodialysis patients

PURPOSE

We applied a previously established common T-score metric for patient-reported and performance-based physical function (PF), offering the unique opportunity to directly compare measurement type-specific patterns of associations with potential laboratory-based, psychosocial, sociodemographic, and health-related determinants in hemodialysis patients.

METHODS

We analyzed baseline data from the CONVINCE trial (N = 1,360), a multinational randomized controlled trial comparing high-flux hemodialysis with high-dose hemodiafiltration. To explore the associations of potential determinants with performance-based versus patient-reported PF, we conducted multiple linear regression (backward elimination with cross-validation and Lasso regression). We used standardized T-scores as estimated from the PROMIS PF short-form 4a (patient-reported PF) and the Physical Performance Test (performance-based PF) as dependent variables.

RESULTS

Performance-based and patient-reported PF were both significantly associated with a laboratory marker-based indicator of muscle mass (simplified creatinine index), although the effects were relatively small (partial f2 = 0.04). Age was negatively associated with PF; the effect size was larger for performance-based (partial f2 = 0.12) than for patient-reported PF (partial f2 = 0.08). Compared to performance-based PF, patient-reported PF showed a stronger association with self-reported health domains, particularly pain interference and fatigue. When using the individual difference between patient-reported and performance-based T-scores as outcome, we found that younger age and more fatigue were associated with lower patient-reported PF compared to performance-based PF (small effect size).

CONCLUSION

Patient-reported and performance-based assessments were similarly associated with an objective marker of physical impairment in hemodialysis patients. Age and fatigue may result in discrepancies when comparing performance-based and patient-reported scores on the common PF scale. Trial Registration CONVINCE is registered in the Dutch Trial Register (Register ID: NL64750.041.18). The registration can be accessed at: https://onderzoekmetmensen.nl/en/trial/52958 .

Association of the modified creatinine index with quality of life in haemodialysis patients

Aims/Background The evaluation of health-related quality of life in patients undergoing maintenance haemodialysis has garnered increasing attention. The modified creatinine index, a surrogate marker for muscle mass, has been linked to various clinical outcomes. However, the relationship between modified creatinine index and health-related quality of life in maintenance haemodialysis patients remains unclear. This study aims to elucidate the association between modified creatinine index and health-related quality of life in individuals receiving maintenance haemodialysis. Methods This cross-sectional study included 217 maintenance haemodialysis patients. Health-related quality of life was assessed using the Kidney Disease Quality of Life Instrument. Collected data included general patient information, laboratory results, and haemodialysis-related parameters. The modified creatinine index was calculated based on gender, age, single-pool Kt/V (spKt/V), and pre-dialysis serum creatinine levels. Multiple linear regression models and smooth curve fitting were used to investigate the relationship between modified creatinine index and health-related quality of life. Subgroup analyses and interaction tests were performed to identify potential effect modifiers. Results The 217 maintenance haemodialysis patients had a mean age of 53.66±13.15 years and a median dialysis vintage of 39 (25-84) months; 120 (55.30%) were male. The mean health-related quality of life score was 55.76±10.33, and the mean modified creatinine index was 22.72±2.95 mg/kg/day. After adjusting for confounding factors, an increase in modified creatinine index was associated with an improvement in health-related quality of life (β=0.55, 95% CI: 0.04, 1.06, p = 0.033). No nonlinear relationship was identified between modified creatinine index and health-related quality of life by smooth curve fitting. Subgroup and interaction analyses indicated that the relationship between modified creatinine index and health-related quality of life was stable and not significantly influenced by age, gender, dialysis vintage, diabetes status, or body mass index (p > 0.05). Conclusion Modified creatinine index is positively correlated with health-related quality of life in maintenance haemodialysis patients, suggesting its potential utility in evaluating patient quality of life. Modified creatinine index could be clinically useful to improve the predictability of health-related quality of life in maintenance haemodialysis patients.

Prevalence and relevance of cachexia as diagnosed by two different definitions in patients undergoing hemodialysis: A retrospective and exploratory study

OBJECTIVE

Cachexia is present in various chronic diseases and is associated with decreased quality of life and increased risk of morbidity and mortality. However, evidence regarding the association of cachexia with prognosis in patients undergoing hemodialysis is limited. We assessed cachexia using two definitions and compared prevalence, functional impairment, and prognostic impact in patients undergoing hemodialysis.

METHODS

We enrolled outpatients undergoing hemodialysis at two centers retrospectively. We assessed cachexia using the conventional cachexia (Evans' criteria) and the Asian Working Group for Cachexia (AWGC) criteria. The study examined all-cause mortality and functional status (Clinical Frailty Scale and short physical performance battery). We used Cox proportional hazards model to examine the association with prognosis, and logistic regression analysis to examine the association with functional impairment.

RESULTS

Among 367 patients (mean age, 67 years; 63 % male), cachexia prevalence, as defined by Evans' criteria and AWGC, was 21.3 % and 35.2 %, respectively. Cachexia as defined by Evans' criteria was associated with an increased risk of all-cause mortality (hazard ratio [HR], 95 % confidence interval [CI]: 1.81, 1.02-3.23). Also, cachexia as defined by AWGC criteria showed suggestive association with increasing mortality (HR, 95 % CI: 1.56, 0.90-2.70). Similar results were seen between cachexia and functional impairment.

CONCLUSIONS

Among patients on hemodialysis, cachexia was highly prevalent and was associated with poor prognosis and functional impairment. Detecting cachexia in earlier stages may be useful for risk stratification in this population.

Simplified Creatinine Index as Predictor of Malnutrition in Stage 5 Chronic Kidney Disease Patients on Maintenance Haemodialysis

Background

Malnutrition inflammation score (MIS) is an instrument for assessing the nutritional status of stage 5 CKD patients, while simplified creatinine index (SCI) is used to assess muscle mass indirectly.

Purpose

This study aims to analyse the correlation between SCI and MIS, as well as determine the SCI cut-off value as a predictor of malnutrition in stage 5 CKD patients on maintenance HD.

Methods

This research was an analytical observational study with a cross-sectional study approach. The 132 research subjects were stage 5 CKD patients at the HD Unit of RSUP Dr. Hasan Sadikin Bandung. The research used the Rank-Spearman test with SPSS for correlative bivariate analysis. The area under the curve (AUC) on the receiver operating characteristic (ROC) curve was analysed to find the SCI cut-off value as a predictor of malnutrition in stage 5 CKD patients.

Results

Sixty-three subjects (47.7%) were classified as good nutrition and 69 subjects (52.3%) as poor nutrition. The average SCI value in this study was 24.5 mg/kg/day ± SD 3.2 mg/kg/day, with a median MIS value was 6. This study showed a significant negative correlation between SCI and MIS (r = -0.586, p < 0.001). The optimal SCI cut-off from the ROC curve analysis value was ≤ 24.53 mg/kg/day (sensitivity = 76.8%; specificity = 79.4%).

Conclusion

A negative correlation existed between SCI and MIS, with an SCI value ≤ 24.53 indicating poor nutritional status in stage 5 CKD patients on maintenance HD. SCI can be used as a predictor of malnutrition at a lower cost and easier.

Intramuscular and abdominal fat measured by computed tomography and mortality of hemodialysis patients

BACKGROUND

In hemodialysis patients, high body mass index is associated with low mortality while abdominal obesity relates to increased mortality. We aimed to investigate the association between muscle mass, intramuscular fat and abdominal fat measured by abdominal computed tomography (CT), and mortality in this patients population.

METHODS

This two-center retrospective cohort study included hemodialysis patients who underwent abdominal CT between January 2013 and December 2018. Skeletal muscle mass index (SMI), muscle radiation attenuation (MRA) as an index of intramuscular fat, and visceral fat to subcutaneous fat ratio (VSR) were calculated using CT images at the third lumbar vertebral level. Multivariate Cox proportional hazards model was used to determine the independent predictors of all-cause, cardiovascular and non-cardiovascular mortalities.

RESULTS

The study included 344 patients (median age 71.0 years; female 33.7%), among whom 145 died during a median follow-up of 4.9 years-46 and 99 from cardiovascular and non-cardiovascular causes, respectively. Lower MRA [hazard ratio (HR) 0.71, 95% confidence interval (CI) 0.58-0.87, P = .001] and higher VSR (HR 1.17, 95% CI 1.01-1.37, P = .04) were independently associated with higher all-cause mortality but not with lower SMI (HR 0.87, 95% CI 0.68-1.11, P = .26). Lower MRA (HR 0.51, 95% CI 0.35-0.73, P < .001) and higher VSR (HR 1.29, 95% CI 1.09-1.54, P = .003) were also associated with cardiovascular and non-cardiovascular mortality, respectively.

CONCLUSIONS

Intramuscular fat and abdominal fat as measured using abdominal CT in hemodialysis patients are stronger independent predictors of mortality than muscle mass.

Importance of dialysis specialists in early mortality in elderly hemodialysis patients: a multicenter retrospective cohort study

The early mortality rate in elderly patients undergoing hemodialysis is more than twice that in young patients, requiring more specialized healthcare. We investigated whether the number of professional dialysis specialists affected early mortality in elderly patients undergoing hemodialysis. This multicenter retrospective cohort study analyzed data from 1860 patients aged ≥ 70 years who started hemodialysis between January 2010 and December 2017. Study regions included Seoul, Gyeonggi-do, Gangwon-do, Daejeon/Chungcheong-do, Daegu/Gyeongsangbuk-do, and Busan/Ulsan/Gyeongsangnam-do. The number of patients undergoing hemodialysis per dialysis specialist was calculated using registered data from each hemodialysis center. Early mortality was defined as death within 6 months of hemodialysis initiation. Gangwon-do (28.3%) and Seoul (14.5%) showed the highest and lowest early mortality rate, respectively. Similarly, Gangwon-do (64.6) and Seoul (43.9) had the highest and lowest number of patients per dialysis specialist, respectively. Relatively consistent results were observed for the regional rankings of early mortality rate and number of patients per dialysis specialist. Multivariate Cox regression analysis-adjusted for previously known significant risk factors-revealed that the number of patients per dialysis specialist was an independent risk factor for early mortality (hazard ratio: 1.031, p < 0.001). This study underscores the growing need for dialysis specialists for elderly hemodialysis patients in Korea.

Muscle Mass and Serum Creatinine Concentration by Race and Ethnicity among Hemodialysis Patients

SIGNIFICANCE STATEMENT

Serum creatinine is a product of skeletal muscle metabolism. Differences in serum creatinine concentration between Black and non-Black individuals have been attributed to differences in muscle mass but have not been thoroughly examined. Furthermore, other race and ethnic groups have not been considered. If differences in body composition explain differences in serum concentration by race or ethnicity, then estimates of body composition could be used in eGFR equations rather than race. Adjustment for intracellular water (ICW) as a proxy of muscle mass among patients with kidney failure in whom creatinine clearance should minimally influence serum concentration does not explain race- and ethnicity-dependent differences.

BACKGROUND

Differences in serum creatinine concentration among groups defined by race and ethnicity have been ascribed to differences in muscle mass. We examined differences in serum creatinine by race and ethnicity in a cohort of patients receiving hemodialysis in whom creatinine elimination by the kidney should have little or no effect on serum creatinine concentration and considered whether these differences persisted after adjustment for proxies of muscle mass.

METHODS

We analyzed data from 501 participants in the A Cohort Study to Investigate the Value of Exercise in ESKD/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESKD study who had been receiving hemodialysis for >1 year. We examined the independent associations among race and ethnicity (Black, Asian, non-Hispanic White, and Hispanic), serum creatinine, and ICW (L/m 2 ), a proxy for muscle mass, derived by whole-body multifrequency bioimpedance spectroscopy, using multivariable linear regression with adjustment for several demographic, clinical, and laboratory characteristics. We examined the association of race and ethnicity with serum creatinine concentration with and without adjustment for ICW.

RESULTS

Black, Asian, and Hispanic patients had higher serum creatinine concentrations (+1.68 mg/dl [95% confidence interval (CI), 1.09 to 2.27], +1.61 mg/dl [95% CI, 0.90 to 2.32], and +0.83 [95% CI, 0.08 to 1.57], respectively) than non-Hispanic White patients. Overall, ICW was associated with serum creatinine concentration (0.26 mg/dl per L/m 2 ICW; 95% CI, 0.006 to 0.51) but was not statistically significantly different by race and ethnicity. Black, Asian, and Hispanic race and ethnicity remained significantly associated with serum creatinine concentration after adjustment for ICW.

CONCLUSION

Among patients receiving dialysis, serum creatinine was higher in Black, Asian, and Hispanic patients than in non-Hispanic White patients. Differences in ICW did not explain the differences in serum creatinine concentration across race groups.

Creatinine index: a retrospective cohort study in an urban Australian dialysis context

AIM

This study aimed to described the relationship between the CI and mortality in an Australian context.

INTRODUCTION

Maintenance haemodialysis is a catabolic state associated with a significant decrease in lean body mass (LBM) and protein energy wasting. LBM can be derived or estimated from creatinine kinetic modelling, specifically the creatinine index (CI). This has been demonstrated in cohort studies to predict mortality.

METHODS

One hundred seventy-nine patients undergoing haemodialysis in 2015 were included in this cohort. They were followed for 5 years with pertinent clinical data collected to calculate the CI as of December 2015. For analysis, patients were split into a high and low CI group based on the median (18.32 mg/kg/day). The primary outcome of interest was all-cause mortality, and secondary outcomes included myocardial infarction, stroke and transplantation.

RESULTS

During follow-up, 69 (76.7%) patients in the low CI group and 28 (31.5%) patients in the high CI group died (P < 0.001). The relative risk (RR) of mortality within the low compared with the high CI group was 2.43 (95% confidence interval, 1.75-3.38). Fully adjusted Cox proportional hazards modelling demonstrated a hazard ratio (HR) of 0.498 (95% CI, 0.292-0.848) for survival in the high CI group. Lower CI was associated with increased risk of stroke (RR, 5.43 [95% CI, 1.24-23.84]), whereas transplant was more likely in the high CI group (RR, 6.4 [95% confidence interval, 1.96-20.88]).

CONCLUSIONS

In a single-centre Australian haemodialysis cohort, the CI was strongly associated with mortality and stroke risk. The CI is an accurate and simple method to identify patients with low LBM at risk for significant morbidity and mortality.

Longitudinal profiling and tracking stability in the Singapore study of macro-angiopathy and microvascular reactivity in type 2 diabetes cohort

INTRODUCTION

The Singapore Study of Macro-Angiopathy and microvascular Reactivity in Type 2 Diabetes (SMART2D) is a prospective cohort study which was started in 2011 to investigate the effect of risk factors on vascular function and diabetes-related complications in Asians. We aimed to compare the longitudinal change in risk factors by accounting for batch effect and assess the tracking stability of risk factors over time in patients recruited for SMART2D. In this study, we (1) described batch effect and its extent across a heterogenous range of longitudinal data parameters; (2) mitigated batch effect through statistical approach; and (3) assessed the tracking stability of the risk factors over time.

METHODS

A total of 2258 patients with type 2 diabetes mellitus (T2DM) were recruited at baseline. The study adopted a three-wave longitudinal design with intervals of 3 years between consecutive waves. The changes in a few selected risk factors were assessed after calibration, assuming patients with similar demographic and anthropometry profile had similar physiology. The tracking pattern of the risk factors was determined with stability coefficients derived from generalised estimating equations.

RESULTS

The medians of the longitudinal differences in risk factors between the waves were mostly modest at <10%. Larger increases in augmentation index (AI), aortic systolic blood pressure (BP) and aortic mean BP were consistently observed after calibration. The medians of the longitudinal differences in AI, aortic systolic BP and aortic mean BP between the waves were <2% before calibration, but increased slightly to <5% after calibration. Most of the risk factors had moderate to high tracking stability. Muscle mass and serum creatinine were among those with relatively high tracking stability.

CONCLUSIONS

The longitudinal differences in parameters between the waves were overall modest after calibration, suggesting that calibration may attenuate longitudinal differences inflated by non-biological factors such as systematic drift due to batch effect. Changes of the hemodynamic parameters are robust over time and not entirely attributable to age. Our study also demonstrated moderate to high tracking stability for most of the parameters.

Serum creatinine-to-cystatin C ratio as an indicator of sarcopenia in hemodialysis patients

BACKGROUND AND AIMS

In hemodialysis patients, sarcopenia is common and related to morbidity and mortality. In non-dialysis patients, the serum creatinine-to-cystatin C (Cre/Cys-C) ratio is a marker of sarcopenia. Its clinical utility in hemodialysis populations, however, is still unknown. Our study aimed to determine whether sarcopenia could be detected using the Cre/Cys-C ratio in hemodialysis patients.

METHODS

This retrospective cross-sectional study included 85 hemodialysis patients whose handgrip strength (HGS) and bioimpedance analysis-estimated skeletal muscle index (SMI) were assessed. Sarcopenia was diagnosed as a combination of reduced muscle strength (women: HGS <18 kg; men: HGS <28 kg) and decreased muscle mass volume (women: SMI <5.7 kg/m²; men: SMI <7.0 kg/m²).

RESULTS

Sarcopenia was observed in 33 (38.8%) patients. Patients with sarcopenia had a significantly lower Cre/Cys-C ratio than those without (1.3 ± 0.2 vs 1.7 ± 0.3, respectively; p < 0.0001). The Cre/Cys-C ratio was independently associated with HGS (β = 0.303, p = 0.011) and SMI (β = 0.376, p = 0.0007). After adjustment for sex and age, the C-statistic of the Cre/Cys-C ratio that predicted sarcopenia was 0.898 (95% CI [0.827, 0.969], p < 0.0001). Moreover, as Cre/Cys-C ratios increased, the risk of sarcopenia significantly decreased (adjusted OR: 0.665 for each 0.1 increase in the Cre/Cys-C ratio) (95% CI [0.501, 0.857], p = 0.0002).

CONCLUSION

The Cre/Cys-C ratio may be a helpful prediction tool for sarcopenia in patients receiving hemodialysis.

Physical performance tasks were linked to the PROMIS physical function metric in patients undergoing hemodialysis

OBJECTIVES

To investigate whether a multi-item performance outcome measure, the physical performance test (PPT), can be calibrated to a common scale with patient-reported outcome measures, using the Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) metric.

STUDY DESIGN AND SETTING

We analyzed baseline data (N = 1,113) from the CONVINCE study, an international trial in end-stage kidney disease patients comparing high-dose hemodiafiltration with high-flux hemodialysis. Assumptions of item response theory (IRT) modelling were investigated for the combined set of the nine-item PPT and a four-item PROMIS PF short form (PROMIS-PF4a). We applied unidimensional IRT linking for calibrating the PPT to the PROMIS PF metric.

RESULTS

Although some evidence for multidimensionality was found, classical test statistics (Cronbach's Alpha = 0.93), Mokken (Loevinger's H = 0.50), and bifactor analysis (explained common variance = 0.65) indicated that PPT and PROMIS-PF4a items can be used to assess a common PF construct. On the group level, the agreement between PROMIS-PF4a and linked PPT scores was stable across several subsamples. On the individual level, scores differed considerably.

CONCLUSION

We found preliminary evidence that the PPT can be linked to the PROMIS PF metric in hemodialysis patients, enabling group comparisons across patient-reported outcome and performance outcome measures. Alternative linking methods should be applied in future studies using a more comprehensive PROMIS PF item set.

Low Serum Creatinine Levels in Early Pregnancy Are Associated with a Higher Incidence of Postpartum Abnormal Glucose Metabolism among Women with Gestational Diabetes Mellitus: A Retrospective Cohort Study

The predictive factors for the progression from gestational diabetes mellitus (GDM) to type 2 diabetes remain incompletely elucidated. Our objective was to investigate the link between serum creatinine, a proxy for skeletal muscle mass, and the development of postpartum abnormal glucose metabolism (AGM).

METHODS

A retrospective review of the medical records of 501 women with GDM was conducted, all of whom underwent a 75 g oral glucose tolerance test (OGTT) between 4 and 12 weeks postpartum. Women were grouped based on quartiles of serum creatinine at the first antenatal visit to estimate the association between serum creatinine and postpartum AGM incidence.

RESULTS

Compared with the highest quartile of creatinine, lower quartiles were substantially linked to an increased incidence of postpartum AGM (adjusted odds ratios 3.37 [95% CI 1.77-6.42], 2.42 [95% CI 1.29-4.51] and 2.27 [95% CI 1.23-4.18], respectively). The generalized additive model suggested a linear relationship between serum creatinine levels and the risk of postpartum AGM below 68 µmol/L of serum creatinine levels. A decrease of 2 μmol/L in serum creatinine levels was found to be associated with a 10% increase in the odds of developing postpartum AGM. Linear regression revealed that a low serum creatinine level was linked to a higher postpartum 2-h glucose level and a decreased insulinogenic index (p = 0.007 and p = 0.027, respectively).

CONCLUSIONS

An association was observed between lower serum creatinine levels in early pregnancy and an increased risk of postpartum AGM and poorer β-cell function in women with a recent history of GDM. Further research is needed to understand the mechanisms underlying our findings, as well as the role of skeletal muscle mass or nutritional status in early pregnancy on later glucose metabolism.

A Novel Creatinine Muscle Index Based on Creatinine Filtration: Associations with Frailty and Mortality

SIGNIFICANCE STATEMENT

Low muscle mass is related to frailty and increased mortality in older adults. However, muscle mass is not easily assessed in routine clinical practice. This paper describes a novel creatinine muscle index (CMI) on the basis of serum creatinine and cystatin C. CMI was moderately associated with frailty among older adults. A significantly higher proportion of individuals with weak grip strength were in the lowest tertile of CMI. The index was also associated with mortality. These results are consistent with the hypothesis that creatinine filtration may be an index of muscle mass, which may have utility in clinical practice.

BACKGROUND

Low muscle mass is related to frailty and increased mortality in older adults. However, muscle mass is not easily assessed in routine clinical practice.

METHODS

This study describes a novel creatinine muscle index (CMI) on the basis of serum creatinine and cystatin C in a community-based sample of older adults from the Atherosclerosis Risk in Communities Study. Analyses included 4639 participants who attended visit 5 (2011-2013) and 12,786 participants who attended visit 2 (1990-1992). CMI was defined as creatinine filtration (the product of serum creatinine times eGFR on the basis of cystatin C) and was analyzed in sex-specific tertiles. Cross-sectional associations of CMI with a frailty trichotomy, defined by the number (robust [0]/prefrail [1-2]/frail [3-5]) of five frailty components (weight loss, slowness, exhaustion, weakness, and low physical activity), were studied using polychotomous logistic regression and binary logistic regression with each frailty component. Cox regression was used to estimate associations of CMI at visit 5 and visit 2 with mortality. Models were adjusted for demographics, clinical variables, and comorbid conditions.

RESULTS

CMI (tertile 1 versus 3) was moderately associated with frailty (visit 5: adjusted odds ratio 4.23 [95% confidence interval (CI), 2.02 to 8.87] in men and 2.34 [95% CI, 1.41 to 3.89] in women) and with mortality (visit 5: adjusted hazard ratio 1.45 [95% CI, 1.08 to 1.94] in men and 1.55 [95% CI, 1.13 to 2.12] in women; similar results were seen at visit 2).

CONCLUSION

Lower CMI was associated with frailty and increased mortality, two clinical outcomes known to be associated with decreased muscle mass. Creatinine filtration may be an index of muscle mass and have utility in clinical practice, particularly at low levels.

Ratio of extracellular water to intracellular water and simplified creatinine index as predictors of all-cause mortality for patients receiving hemodialysis

The bioelectrical impedance analysis-measured ratio of extracellular water (ECW) to intracellular water (ICW) reflects fluid volume and malnutrition. It may be an indicator of protein-energy wasting and muscle wasting in hemodialysis patients. We examined the association between the ECW/ICW ratio and simplified creatinine index, which is a new surrogate marker of protein-energy wasting and muscle wasting, and whether their combination can accurately predict mortality. A total of 224 patients undergoing hemodialysis for more than 6 months and having undergone bioelectrical impedance analysis for the assessment of body composition were included. Patients were divided into two groups based on the cut-off values of the ECW/ICW ratio (0.57) and simplified creatinine index (20.4 mg/kg/day) for maximumly predicting mortality. Thereafter, they were cross-classified into four groups with each cut-off point. The ECW/ICW ratio was independently associated with the simplified creatinine index (β = -0.164; P = 0.042). During a follow-up of 3.5 years (2.0-6.0 years), 77 patients died. A higher ECW/ICW ratio (adjusted hazard ratio, 3.66, 95% confidence interval 1.99-6.72, P <0.0001) and lower simplified creatinine index (adjusted hazard ratio, 2.25, 95% confidence interval 1.34-3.79, P = 0.0021) were independently associated with an increased risk of all-cause mortality. The adjusted hazard ratio for the higher ECW/ICW ratio and lower simplified creatinine index group vs. the lower ECW/ICW ratio and higher simplified creatinine index group was 12.22 (95% confidence interval 3.68-40.57, p <0.0001). Furthermore, the addition of the ECW/ICW ratio and simplified creatinine index to the baseline risk model significantly improved the C-index from 0.831 to 0.864 (p = 0.045). In conclusion, the ECW/ICW ratio may be a surrogate marker of muscle wasting. Moreover, combining the ECW/ICW ratio and simplified creatinine index may improve the accuracy of predicting all-cause mortality and help stratify the mortality risk of hemodialysis patients.

The effect of changing dialysate bicarbonate concentration on serum bicarbonate, body weight and normalized nitrogen appearance rate

INTRODUCTION

Most hemodialysis machines deliver a fixed bicarbonate concentration. Higher concentrations may improve acidosis, but risk post-hemodialysis alkalosis, whereas lower concentrations potentially increase acidosis but reduce alkalosis. We reviewed the effects of lowering dialysate bicarbonate.

METHODS

We reviewed peri-dialysis chemistries in patients switching to a lower bicarbonate dialysate at 4 time points over 19 months.

RESULTS

We studied 126 patients, mean age 63.7 ± 16.3 years, 57.9% males. Post-hemodialysis alkalosis fell from 1.6 to 0.3% sessions, but pre-hemodialysis acidosis increased from 11.9 to 23.8% sessions (p = 0.005) reducing dialysate bicarbonate from 32 to 28 mmol/L. After 3 months, pre-hemodialysis serum bicarbonate fell (21.1 ± 2.3 to 19.8 ± 2.2 mmol/L), and post-hemodialysis (24.9 ± 2.1 to 22.5 ± 2.0 mmol/L, p < 0.001) with a fall in pre-hemodialysis weight from 74.6 ± 20.7 to 71.7 ± 18.2 kg, normalized protein nitrogen accumulation rate 0.8 ± 0.28 to 0.77 ± 0.2 g/kg/day, p < 0.05, and serum albumin 39.7 ± 4.2 to 37.7 ± 4.9 g/L, p < 0.001. Thereafter, apart from pre- and post-hemodialysis serum bicarbonate, weight and normalized protein nitrogen accumulation stabilized, although albumin remained lower (37.6 ± 4.0 g/L, p < 0.001). On multivariate logistic analysis, serum bicarbonate increased more with lower pre-hemodialysis bicarbonate standardized coefficient β 0.5 (95% confidence interval -0.6 to -0.42), increased normalized protein nitrogen accumulation β 0.2 (0.96 to 2.38), p < 0.001, and session time β 0.09, (0.47 to 5.98), p < 0.022, and less with lower dialysate bicarbonate 0.0-0.23 (-1.54 to -0.74), p < 0.001.

CONCLUSION

Increases in SE-Bic with hemodialysis, depend on the bicarbonate gradient, session time and nPNA. Lower D-Bic reduces post-hemodialysis alkalosis but increases pre-hemodialysis acidosis and may initially have adverse effects on weight and normalized protein nitrogen accumulation.

Association of the modified creatinine index with muscle strength and mortality in patients undergoing hemodialysis

Background

In the updated consensus, low muscle strength overtook the role of low muscle mass, and probable sarcopenia was diagnosed once low muscle strength was detected. Whether the modified creatinine index (mCI) could identify persons with probable sarcopenia who may be at risk of adverse outcomes remains unknown. We aimed to evaluate the association of the mCI with probable sarcopenia and mortality in patients undergoing hemodialysis.

Methods

In the cross-sectional study (n = 346), univariate and multivariable logistic regression analyses were performed to study the association of mCI with probable sarcopenia. Modified Quantitative Subjective Global Assessment (MQSGA) was used to evaluate the nutritional status. The performance of the mCI value for identifying probable sarcopenia was analyzed using receiver operating characteristic (ROC) curve analysis. The appropriate cutoff points were determined using Youden’s method. In the longitudinal cohort study composed of an independent hemodialysis cohort (n = 218), cox proportional regression models were used to evaluate crude and adjusted hazard ratios and 95% confidence intervals (CIs) of death by mCI and MQSGA.

Results

Cross-sectional results showed that after adjusting for confounders, the association of mCI with low muscle strength remained significant. The area under the curve (AUC) of the mCI to predict probable sarcopenia was 0.804 (95% CI, 0.744–0.863; p < 0.001) for men and 0.787 (95% CI, 0.711–0.864; p < 0.001) for women. The optimal mCI cutoff values were 21.07 mg/kg/d for men and 19.57 mg/kg/d for women, respectively. Longitudinal results showed that compared with those in the high mCI group, subjects in the low mCI group had a higher risk of death for all causes (adjusted HR, 2.51; 95% CI, 1.16–5.41; p = 0.019). Adding the mCI significantly improved the predictive accuracy for death with an increase in C-index from 0.785 to 0.805 (p = 0.026) and improved the net reclassification index (38.6%, p = 0.021), while adding MQSGA did not.

Conclusion

The mCI is a predictor of muscle strength and survival in hemodialysis patients, and is preferable to the MQSGA for predicting death. Assessment of mCI could provide additional predictive and prognostic information to sarcopenia.

Simplified discriminant parameters for sarcopenia among patients undergoing haemodialysis

BACKGROUND

Patients with end-stage renal disease (ESRD) are at an increased risk of developing sarcopenia, which can lead to various adverse health outcomes. Although the diagnosis of sarcopenia is essential for clinical management, it is not feasible in routine clinical practice for populations undergoing haemodialysis because it is time-consuming and resources are limited. Serum creatinine levels in patients with ESRD have been gaining attention as a screening parameter for sarcopenia because serum creatinine is a routinely measured byproduct of skeletal muscle metabolism. This study aimed to evaluate the discriminative ability of the creatinine-derived index for sarcopenia in patients undergoing haemodialysis.

METHODS

We diagnosed sarcopenia according to the Asian Working Group for Sarcopenia (AWGS) 2 criteria in 356 clinically stable outpatients with ESRD enrolled from three dialysis facilities. We adopted the modified creatinine index as a simplified discriminant parameter for sarcopenia in addition to the calf circumference, SARC-F score, and combination of both (i.e. SARC-CalF score), which are recommended by the AWGS. Receiver operating characteristic analysis and logistic regression analysis were conducted to evaluate the discriminative ability of the modified creatinine index for sarcopenia.

RESULTS

Of the study participants, 142 (39.9%) were diagnosed with sarcopenia. The areas under the curve of the modified creatinine index against sarcopenia in the male and female participants were 0.77 (95% confidence interval [CI]: 0.71 to 0.83) and 0.77 (95% CI: 0.69 to 0.85), respectively. All simplified discriminant parameters were significantly associated with sarcopenia, even after adjusting for patient characteristics and centre. In the comparison of the odds ratios for sarcopenia for 1-standard deviation change in the simplified discriminant parameters, the odds ratio of the modified creatinine index was 1.92 (95% CI: 1.15 to 3.19), which was lower than that of the calf circumference (odds ratio: 6.58, 95% CI: 3.32 to 13.0) and similar to that of the SARC-F (odds ratio: 1.57, 95% CI: 1.14 to 2.16) and SARC-CalF scores (odds ratio: 2.36, 95% CI: 1.60 to 3.47).

CONCLUSIONS

This study revealed a strong association between the creatinine-derived index and sarcopenia in patients undergoing haemodialysis. The modified creatinine index was equal or superior to those of SARC-F and SARC-CalF score in discriminability for sarcopenia. However, the ability of the calf circumference to discriminate sarcopenia is extremely high, and further study is needed to determine whether it can be used to detect deterioration of muscle mass and function over time.

Cardiac valve calcification in patients on maintenance dialysis. The role of malnutrition-inflammation syndrome, adiposity andcomponents of sarcopenia. A cross-sectional study

BACKGROUND & AIMS

Cardiac valve calcification (CVC) is a predictor of cardiovascular disease and all-cause mortality in end stage kidney disease (ESKD) patients. Several risk factors are related to CVC in patients with ESKD including traditional ones as well as inflammation, bone mineral disease and malnutrition. Adiposity is associated with dyslipidemia and proinflammatory activity which could predispose for CVC. Sarcopenia or dynapenia is a state common in patients with ESKD. This study aimed to investigate the relationship of adiposity, sarcopenia and malnutrition-inflammation markers with CVC in patients on maintenance hemodialysis.

METHODS

CVC in aortic (AVC), mitral valves (MVC) and systolic and diastolic dysfunction (DD) were assessed by using two-dimensional echocardiography. Nutritional, adiposity and anthropometric assessments were made using several indices respectively. Creatinine index and muscle strength measurements were also performed. Biochemical parameters such as total proteins, albumin, calcium, phosphate, plasma lipoproteins, C-Reactive Protein and parathyroid hormone were also measured.

RESULTS

Adiposity, nutritional, and sarcopenia parameters did not show any difference between patients with or without CVC. Age ≥ 65 years [PR: 1.47 p = 0.012], DD [PR: 2.31, p = 0.005], high CRP/albumin ratio [PR: 1.46, p = 0.01], mid arm circumference (MAC) < 26 cm [PR: 1.37, p = 0.03] were associated with increased prevalence of AVC, while DD [PR: 1.97 p = 0.02], high CRP/albumin ratio [PR: 1.56, p = 0.02], and MAC < 26 cm [PR: 1.52, p = 0.01], showed positive correlation with MVC. Age ≥ 65 years [PR: 1.33, p = 0.028], DD [PR: 1.72, p = 0.01], high CRP/albumin ratio [PR: 1.53, p = 0.003], and MAC < 26 cm [PR: 1.4, p = 0.006], related to greater prevalence of calcification at any valve.

CONCLUSIONS

Ageing, diastolic dysfunction, MAC and increased CRP/albumin ratio were powerful predictors of CVC in patients on hemodialysis.

Impact of Hydrophilic Modification of Synthetic Dialysis Membranes on Hemocompatibility and Performance

The dialyzer is the core element in the hemodialysis treatment of patients with end-stage kidney disease (ESKD). During hemodialysis treatment, the dialyzer replaces the function of the kidney by removing small and middle-molecular weight uremic toxins, while retaining essential proteins. Meanwhile, a dialyzer should have the best possible hemocompatibility profile as the perpetuated contact of blood with artificial surfaces triggers complement activation, coagulation and immune cell activation, and even low-level activation repeated chronically over years may lead to undesired effects. During hemodialysis, the adsorption of plasma proteins to the dialyzer membrane leads to a formation of a secondary membrane, which can compromise both the uremic toxin removal and hemocompatibility of the dialyzer. Hydrophilic modifications of novel dialysis membranes have been shown to reduce protein adsorption, leading to better hemocompatibility profile and performance stability during dialysis treatments. This review article focuses on the importance of performance and hemocompatibility of dialysis membranes for the treatment of dialysis patients and summarizes recent studies on the impact of protein adsorption and hydrophilic modifications of membranes on these two core elements of a dialyzer.

Longitudinal causal effect of modified creatinine index on all-cause mortality in patients with end-stage renal disease: Accounting for time-varying confounders using G-estimation

BACKGROUND

Standard regression modeling may cause biased effect estimates in the presence of time-varying confounders affected by prior exposure. This study aimed to quantify the relationship between declining in modified creatinine index (MCI), as a surrogate marker of lean body mass, and mortality among end stage renal disease (ESRD) patients using G-estimation accounting appropriately for time-varying confounders.

METHODS

A retrospective cohort of all registered ESRD patients (n = 553) was constructed over 8 years from 2011 to 2019, from 3 hemodialysis centers at Kerman, southeast of Iran. According to changes in MCI, patients were dichotomized to either the decline group or no-decline group. Subsequently the effect of interest was estimated using G-estimation and compared with accelerated failure time (AFT) Weibull models using two modelling strategies.

RESULTS

Standard models demonstrated survival time ratios of 0.91 (95% confidence interval [95% CI]: 0.64 to 1.28) and 0.84 (95% CI: 0.58 to 1.23) in patients in the decline MCI group compared to those in no-decline MCI group. This effect was demonstrated to be 0.57 (-95% CI: 0.21 to 0.81) using G-estimation.

CONCLUSION

Declining in MCI increases mortality in patients with ESRD using G-estimation, while the AFT standard models yield biased effect estimate toward the null.

Personalizing treatment in end-stage kidney disease: deciding between hemodiafiltration and hemodialysis based on individualized treatment effect prediction

Background

Previous studies suggest that hemodiafiltration reduces mortality compared to hemodialysis in patients with end-stage kidney disease (ESKD), but controversy surrounding its benefits remain and it is unclear to what extent individual patients benefit from hemodiafiltration. This study aimed to develop and validate a treatment effect prediction model to determine which patients would benefit most from hemodiafiltration compared to hemodialysis in terms of all-cause mortality.

Methods

Individual participant data from four randomized controlled trials comparing hemodiafiltration with hemodialysis on mortality were used to derive a Royston-Parmar model for prediction of absolute treatment effect of hemodiafiltration based on pre-specified patient and disease characteristics. Validation of the model was performed using internal-external cross validation.

Results

The median predicted survival benefit was 44 (Q1-Q3: 44–46) days for every year of treatment with hemodiafiltration compared to hemodialysis. The median survival benefit with hemodiafiltration ranged from 2 to 48 months. Patients who benefited most from hemodiafiltration were younger, less likely to have diabetes or a cardiovascular history and had higher serum creatinine and albumin levels. Internal-external cross validation showed adequate discrimination and calibration.

Conclusion

Although overall mortality is reduced by hemodiafiltration compared to hemodialysis in ESKD patients, the absolute survival benefit can vary greatly between individuals. Our results indicate that the effects of hemodiafiltration on survival can be predicted using a combination of readily available patient and disease characteristics, which could guide shared decision-making.

Hidden risks associated with conventional short intermittent hemodialysis: A call for action to mitigate cardiovascular risk and morbidity

The development of maintenance hemodialysis (HD) for end stage kidney disease patients is a success story that continues to save many lives. Nevertheless, intermittent renal replacement therapy is also a source of recurrent stress for patients. Conventional thrice weekly short HD is an imperfect treatment that only partially corrects uremic abnormalities, increases cardiovascular risk, and exacerbates disease burden. Altering cycles of fluid loading associated with cardiac stretching (interdialytic phase) and then fluid unloading (intradialytic phase) likely contribute to cardiac and vascular damage. This unphysiologic treatment profile combined with cyclic disturbances including osmotic and electrolytic shifts may contribute to morbidity in dialysis patients and augment the health burden of treatment. As such, HD patients are exposed to multiple stressors including cardiocirculatory, inflammatory, biologic, hypoxemic, and nutritional. This cascade of events can be termed the dialysis stress storm and sickness syndrome. Mitigating cardiovascular risk and morbidity associated with conventional intermittent HD appears to be a priority for improving patient experience and reducing disease burden. In this in-depth review, we summarize the hidden effects of intermittent HD therapy, and call for action to improve delivered HD and develop treatment schedules that are better tolerated and associated with fewer adverse effects.

Time-resolving characterization of molecular weight retention changes among three synthetic high-flux dialyzers

BACKGROUND

Toxin removal capacity (i.e. performance) of a dialyzer is not constant but diminishes during treatment, as the adsorption of proteins to the membrane provides an additional barrier to uremic solutes. We investigated time-resolving molecular weight retention changes among synthetic high-flux dialyzers and compare the results with recent data from a randomized controlled trial.

METHODS

In plasma recirculation experiments over 240min, sieving coefficients (SC) for β2-microglobulin, myoglobin and albumin were determined for the FX CorAL (Fresenius Medical Care), ELISIO (Nipro) and xevonta (B. Braun). Molecular weight retention (MWR) curves were generated and the shifts over 120min were characterized. Effective pore radius was determined, and the predicted albumin loss was compared with clinical data.

RESULTS

SC decreased over time for all dialyzers (mean relative decrease across all dialyzers: β2-microglobulin: 8.0% (120min); myoglobin: 56.6% (240min); albumin: 94.1% (240min)). FX CorAL (7.3%, 52.6% and 91.1%) and ELISIO (7.7%, 51.0% and 93.8%) showed a lower decrease than xevonta (9.0%, 66.2% and 97.4%). For all dialyzers, MWR curves shifted towards lower molecular weight, with the lowest shift for FX CorAL (by 0.23nm at SC50%, 120 min) and highest for xevonta (0.50nm). FX CorAL had the highest slope over time and the smallest decrease in the effective pore radius (2min: 2.31nm, 120min: 2.08nm). Predicted albumin loss over 4h was highest for xevonta (609.3mg) and comparable between ELISIO (283.6mg) and FX CorAL (313.3mg).

CONCLUSIONS

Substantial differences in the temporal performance profile of dialyzers exist. The present approach allows characterization of dialyzer permeability changes over time using standard, clinically relevant protein markers.

Combined Evaluation of Geriatric Nutritional Risk Index and Modified Creatinine Index for Predicting Mortality in Patients on Hemodialysis

The geriatric nutritional risk index (GNRI) and modified creatinine index (mCI) are surrogate markers of protein-energy wasting in patients receiving hemodialysis. We aimed to examine whether a combined evaluation of these indices improved mortality prediction in this population. We retrospectively investigated 263 hemodialysis patients divided into two groups, using 91.2 and 20.16 mg/kg/day as cut-off values of GNRI and mCI, respectively. The resultant four groups were reshuffled into four subgroups defined using combinations of cut-off values of both indices and were followed up. During the follow-up period (median: 3.1 years), 103 patients died (46/103, cardiovascular causes). Lower GNRI and lower mCI were independently associated with all-cause mortality (adjusted hazard ratio (aHR) 4.96, 95% confidence intervals (CI) 3.10–7.94, and aHR 1.92, 95% CI 1.22–3.02, respectively). The aHR value for the lower GNRI and lower mCI group vs. the higher GNRI and higher mCI group was 7.95 (95% CI 4.38–14.43). Further, the addition of GNRI and mCI to the baseline risk assessment model significantly improved the C-index of all-cause mortality (0.801 to 0.835, p = 0.025). The simultaneous evaluation of GNRI and mCI could be clinically useful to stratify the risk of mortality and to improve the predictability of mortality in patients on hemodialysis.

Assessment of uremic sarcopenia in dialysis patients: An update

Uremic sarcopenia, which is highly prevalent in dialysis patients, leads to an increased risk of adverse outcomes, such as poor quality of life, falls, fracture, hospitalization, and even mortality. Therefore, early detection of uremic sarcopenia is crucial for administering quick and adequate multidisciplinary therapy to improve clinical outcomes. This review updates the current information about uremic sarcopenia assessment in chronic dialysis patients. We discuss the methods of assessing skeletal muscle mass, strength, and physical performance. We also discuss surrogate markers derived from serum and dialysate creatinine, in addition to emerging screening tools. The prevalence, clinical relevance, and impact of uremic sarcopenia on survival are reviewed and we discuss the limitations and challenges in applying the current working definition of sarcopenia based on the senior population to dialysis patients. The review shows that dialysis patients with skeletal muscle weakness or poor physical performance, either with or without low skeletal muscle mass, should undergo multidisciplinary therapy, included nutritional counseling, lifestyle modification, and exercise intervention, to mitigate the detrimental effects of uremic sarcopenia.

Longitudinal Assessment of Body Composition and Its Association With Survival Among Participants of the ACTIVE/ADIPOSE Study

OBJECTIVES

The importance of muscle wasting as a predictor of mortality in the hemodialysis population is not clear. Lack of association of muscle mass with survival in some studies could be related to reliance on single measures or to incorporation of excess extracellular water (ECW) into estimates of muscle mass. We examined changes in body composition over a 2-year period and the association of body composition with survival.

DESIGN AND METHODS

We analyzed data from 325 adults receiving hemodialysis in the Bay Area. We estimated ECW, intracellular water (ICW), and fat mass by whole-body bioimpedance spectroscopy (BIS) at 0, 12, and 24 months from enrollment. We used linear mixed modeling to examine changes in body mass index and BIS-derived estimates of body composition and Cox modeling with BIS-derived estimates as time-varying independent variables to examine associations between body composition and survival in multivariable analyses.

RESULTS

Body mass index declined over time. Considering individual components of body composition, ICW declined (-0.09 kg/m² per year, 95% confidence interval -0.14 to -0.04), but fat mass and ECW did not change significantly. There were 120 deaths over a median of 5.2 years. The relationship between ICW and mortality was not linear such that the association was steeper at low values of ICW, whereas higher ICW was associated with better survival that was relatively stable above 9 kg/m2. Higher ECW was associated with higher mortality, and fat mass was not associated with survival. These associations were independent of markers of inflammation and nutritional status.

CONCLUSIONS

ICW declined over 2 years in this cohort, whereas fat mass and ECW remained relatively stable. Higher ICW was associated with better survival, but higher fat mass was not. Higher ECW was associated with worse survival. These results suggest that muscle mass may predict survival among patients on hemodialysis.

Creatinine index as a predictive marker of sarcopenia in patients under hemodialysis

PURPOSE

Sarcopenia is a clinical condition that comprises declined skeletal muscle (SM) mass and SM strength, and is a risk factor for physical disability, impaired quality of life, and advanced morbidity and mortality in patients on hemodialysis (HD). The existing difficulty in evaluating SM mass and consequently of sarcopenia, with affordable and practical methods in clinical practice, is well established. The purpose of this study is to examine the creatinine index (CrI), a surrogate of SM mass, as a potential predictive marker of sarcopenia.

METHODS

In this cross-sectional study, we included 130 patients on HD with a mean age of 66.17 ± 12.47 years. SM mass and SM strength were evaluated with CrI and hand grip strength, respectively. Anthropometric, adiposity, nutritional, and biochemical assessments were also performed. Partial correlation and multivariate regression analyses were applied to investigate the association between CrI and SM strength.

RESULTS

Correlation analysis showed that mid-arm circumference, calf circumference, Geriatric nutritional index, and albumin-to-total protein ratio were positively associated with SM strength. Multivariate model indicated that CrI (β = 2.05, p < 0.001) and dialysis duration (β =- 0.53, p = 0.001) were independently related to SM strength. The significant positive correlation between CrI and SM strength remained unaffected even after adjusting for potential confounders.

CONCLUSIONS

Creatinine Index was significantly associated with SM strength highlighting its value as a new emerging practical in clinical setting sarcopenia predictive marker in HD patients.

Dialyzer surface area is a significant predictor of mortality in patients on hemodialysis: a 3-year nationwide cohort study

A target Kt/V of > 1.4 and use of a high-flux dialyzer are recommended for patients on hemodialysis. However, there is little information on the relationship between the dialyzer surface area and mortality in these patients. In this nationwide cohort study, we aimed to clarify this relationship by analyzing data from the Japanese Society for Dialysis Therapy for 2010–2013. We enrolled 234,638 patients on hemodialysis who were divided according to quartile for dialyzer surface area into the S group (small, < 1.5 m²), M group (medium, 1.5 m²), L group (large, 1.6 to < 2.0 m²), or XL group (extra-large, ≥ 2.0 m²). We assessed the association of each group with 3-year mortality using Cox proportional hazards models and performed propensity score matching analysis. By the end of 2013, a total of 53,836 patients on dialysis (22.9%) had died. There was a significant decrease in mortality with larger dialyzer surface areas. The hazard ratio (95% confidence interval) was significantly higher in the S group (1.15 [1.12–1.19], P < 0.0001) and significantly lower in the L group (0.89 [0.87–0.92] P < 0.0001) and XL group (0.75 [0.72–0.78], P < 0.0001) than in the M group as a reference after adjustment for all confounders. Findings were robust in several sensitivity analyses. Furthermore, the findings remained significant after propensity score matching. Hemodialysis using dialyzers, especially super high-flux dialyzers with a larger surface area might reduce mortality rates, and a surface area of ≥ 2.0 m² is superior, even with the same Kt/V.

Butyrylcholinesterase level as an independent prognostic factor for overall survival in patients on maintenance hemodialysis: a single-center retrospective study

BACKGROUND

We investigated whether butyrylcholinesterase (BChE) was independently related to the overall survival (OS) of patients on maintenance hemodialysis (MHD).

METHODS

Baseline information, serum BChE level, and other laboratory data were collected from 295 patients on MHD in a single HD hospital in 2018. We retrospectively investigated the mortality of these patients after 38 months. We assessed the prognostic markers such as the Geriatric Nutritional Risk Index (GNRI), Erythropoiesis Resistance Index (ERI), and Simplified Creatinine Index (SCI) of each patient. The primary objective was to examine the impact of BChE on OS. The secondary objective included the designation of a risk score in predicting the OS.

RESULTS

We evaluated 284 patients. The median value of the serum BChE level was 206 IU/L. Of 284 patients evaluated, eighty-six patients died; all had a higher ERI and a lower serum BChE level, SCI, and GNRI than the surviving patients. The optimal cutoff values of the BChE level, GNRI, ERI, and SCI for OS were 166 IU/L, 90.0, 8.00, and 20.6, respectively. The multivariate Cox regression analysis showed that the age, HD vintage, dialysis dose, GNRI of < 90.0, and serum BChE level of < 166 IU/L (hazard ratio, 2.03; P = 0.003) were the independent prognostic factors. We designed a risk score consisting of the GNRI and serum BChE level. The predictive value of our risk score was superior to that of GNRI alone.

CONCLUSION

The serum BChE level could be an independent prognostic factor for patients on MHD.

Dynapaenia and sarcopaenia in chronic haemodialysis patients: do muscle weakness and atrophy similarly influence poor outcome?

BACKGROUND

Sarcopaenia, defined as a decline in both muscle mass and function, has been recognized as a major determinant of poor outcome in haemodialysis (HD) patients. It is generally assumed that sarcopaenia is driven by muscle atrophy related to protein-energy wasting. However, dynapaenia, defined as weakness without atrophy, has been characterized by a different disease phenotype from sarcopaenia. The aim of this study was to compare the characteristics and prognosis of sarcopaenic and dynapaenic patients among a prospective cohort of chronic HD (CHD) patients.

METHODS

Two hundred and thirty-two CHD patients were enrolled from January to July 2016 and then followed prospectively until December 2018. At inclusion, weakness and atrophy were, respectively, evaluated by maximal voluntary force (MVF) and creatinine index (CI). Sarcopaenia was defined as the association of weakness and atrophy (MVF and CI below the median) while dynapaenia was defined as weakness not related to atrophy (MVF below the median, and CI above the median).

RESULTS

From a total of 187 prevalent CHD patients [65% of men, age 65.3 (49.7-82.0) years], 44 died during the follow-up period of 23.7 (12.4-34.9) months. Sarcopaenia and dynapaenia were observed in 33.7 and 16% of the patients, respectively. Compared with patients with sarcopaenia, patients with dynapaenia were younger and with a lower Charlson score. In contrast, mortality rate was similar in both groups (38 and 27%, respectively). After adjustment for age, sex, lean tissue index, serum albumin, high-sensitivity C-reactive protein (hs-CRP), haemoglobin (Hb), normalized protein catabolic rate (nPCR), dialysis vintage and Charlson score, only patients with dynapaenia were at increased risk of death [hazard ratio (HR) = 2.99, confidence interval 1.18-7.61; P = 0.02].

CONCLUSIONS

Screening for muscle functionality is highly warranted to identify patients with muscle functional impairment without muscle atrophy. In contrast to sarcopaenia, dynapaenia should appear as a phenotype induced by uraemic milieu, characterized by young patients with low Charlson score and poor prognosis outcome independently of serum albumin, hs-CRP, Hb, nPCR and dialysis vintage.

Usefulness of computed tomography-measured psoas muscle thickness per height for predicting mortality in patients undergoing hemodialysis

Computed tomography (CT)-measured psoas muscle thickness standardized for height (PMTH) has emerged as a promising predictor of mortality. The study aimed to investigate whether PMTH could accurately predict mortality in patients undergoing hemodialysis. We examined 207 patients (mean age: 63.1 years; men: 66.2%) undergoing hemodialysis for more than 6 months in hospital affiliated clinic. PMTH was calculated at the L3 vertebra level using CT. Patients were divided according to the PMTH cut-off points: 8.44 mm/m in women and 8.85 mm/m in men; thereafter, they were combined into low and high PMTH groups. PMTH was independently correlated with the simplified creatinine index (β = 0.213, P = 0.021) and geriatric nutritional risk index (β = 0.295, P < 0.0001) in multivariate regression analysis. During a median follow-up of 3.7 (1.8–6.4) years, 76 patients died, including 41 from cardiovascular causes. In the multivariate Cox regression analysis, low PMTH (adjusted hazard ratio, 2.48; 95% confidence interval, 1.36–4.70) was independently associated with an increased risk of all-cause mortality. The addition of binary PMTH groups to the baseline risk model tended to improve net reclassification improvement (0.460, p = 0.060). In conclusion, PMTH may be an indicator of protein energy wasting and a useful tool for predicting mortality in patients undergoing hemodialysis.

Estimation of Muscle Mass in the Integrated Assessment of Patients on Hemodialysis

Assessment of muscle mass (MM) or its proxies, lean tissue mass (LTM) or fat-free mass (FFM), is an integral part of the diagnosis of protein-energy wasting (PEW) and sarcopenia in patients on hemodialysis (HD). Both sarcopenia and PEW are related to a loss of functionality and also increased morbidity and mortality in this patient population. However, loss of MM is a part of a wider spectrum, including inflammation and fluid overload. As both sarcopenia and PEW are amendable to treatment, estimation of MM regularly is therefore of major clinical relevance. Whereas, computer-assisted tomography (CT) or dual-energy X-ray absorptiometry (DXA) is considered a reference method, it is unsuitable as a method for routine clinical monitoring. In this review, different bedside methods to estimate MM or its proxies in patients on HD will be discussed, with emphasis on biochemical methods, simplified creatinine index (SCI), bioimpedance spectroscopy (BIS), and muscle ultrasound (US). Body composition parameters of all methods are related to the outcome and appear relevant in clinical practice. The US is the only parameter by which muscle dimensions are measured. BIS and SCI are also dependent on either theoretical assumptions or the use of population-specific regression equations. Potential caveats of the methods are that SCI can be influenced by residual renal function, BIS can be influenced by fluid overload, although the latter may be circumvented by the use of a three-compartment model, and that muscle US reflects regional and not whole body MM. In conclusion, both SCI and BIS as well as muscle US are all valuable methods that can be applied for bedside nutritional assessment in patients on HD and appear suitable for routine follow-up. The choice for either method depends on local preferences. However, estimation of MM or its proxies should always be part of a multidimensional assessment of the patient followed by a personalized treatment strategy.

Trajectories of clinical and laboratory characteristics associated with COVID-19 in hemodialysis patients by survival

INTRODUCTION

The clinical impact of COVID-19 has not been established in the dialysis population. We evaluated the trajectories of clinical and laboratory parameters in hemodialysis (HD) patients.

METHODS

We used data from adult HD patients treated at an integrated kidney disease company who received a reverse transcription polymerase chain reaction (RT-PCR) test to investigate suspicion of a severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection between May 1 and September 1, 2020. Nonparametric smoothing splines were used to fit data for individual trajectories and estimate the mean change over time in patients testing positive or negative for SARS-CoV-2 and those who survived or died within 30 days of first suspicion or positive test date. For each clinical parameter of interest, the difference in average daily changes between COVID-19 positive versus negative group and COVID-19 survivor versus nonsurvivor group was estimated by fitting a linear mixed effects model based on measurements in the 14 days before (i.e., Day -14 to Day 0) Day 0.

RESULTS

There were 12,836 HD patients with a suspicion of COVID-19 who received RT-PCR testing (8895 SARS-CoV-2 positive). We observed significantly different trends (p < 0.05) in pre-HD systolic blood pressure (SBP), pre-HD pulse rate, body temperature, ferritin, neutrophils, lymphocytes, albumin, and interdialytic weight gain (IDWG) between COVID-19 positive and negative patients. For COVID-19 positive group, we observed significantly different clinical trends (p < 0.05) in pre-HD pulse rate, lymphocytes, neutrophils, and albumin between survivors and nonsurvivors. We also observed that, in the group of survivors, most clinical parameters returned to pre-COVID-19 levels within 60-90 days.

CONCLUSION

We observed unique temporal trends in various clinical and laboratory parameters among HD patients who tested positive versus negative for SARS-CoV-2 infection and those who survived the infection versus those who died. These trends can help to define the physiological disturbances that characterize the onset and course of COVID-19 in HD patients.

High-performance dialyzers and mortality in maintenance hemodialysis patients

Few data are available regarding the association of dialyzer type with prognosis. In Japan, dialyzers are classified as types I, II, III, IV, and V based on β₂-microglobulin clearance rates of < 10, < 30, < 50, < 70, and ≥ 70 mL/min, respectively. We investigated the relationship of the 5 dialyzer types with 1-year mortality. This nationwide cohort study used data collected at the end of 2008 and 2009 by the Japanese Society for Dialysis Therapy Renal Data Registry. We enrolled 203,008 patients on maintenance hemodialysis who underwent hemodialysis for at least 1 year and were managed with any of the 5 dialyzer types. To evaluate the association of dialyzer type with 1-year all-cause mortality, Cox proportional hazards models and propensity score-matched analyses were performed. After adjustment of the data with clinicodemographic factors, the type I, II, and III groups showed significantly higher hazard ratios (HRs) than the type IV dialyzers (reference). After adjustment for Kt/V and β₂-microglobulin levels, the HRs were significantly higher in the type I and II groups. After further adjustment for nutrition- and inflammation-related factors, the HRs were not significantly different between the type IV and type I and II groups. However, type V dialyzers consistently showed a significantly lower HR. With propensity score matching, the HR for the type V dialyzer group was significantly lower than that for the type IV dialyzer group. Additional long-term trials are required to determine whether type V dialyzers, which are high-performance dialyzers, can improve prognosis.

Comparison of Simplified Creatinine Index and Systemic Inflammatory Markers for Nutritional Evaluation of Hemodialysis Patients

Protein-energy wasting (PEW) is associated with adverse outcomes in hemodialysis patients. This study compares the simplified creatinine index (SCI) and circulating inflammatory markers as nutritional screening tools for hemodialysis patients. Maintenance hemodialysis patients (230 total patients, 34.8% women, 64.0 ± 14.3 years old) from a tertiary medical center were assessed for demographic data, body composition analysis, biochemistry tests, and circulating inflammatory biomarkers. The SCI was calculated using Canaud’s formula. Reduced fat-free mass index (FFMI), a surrogate of lean body mass, was identified according to the European Society for Clinical Nutrition and Metabolism guidelines. Nutritional status was assessed by the geriatric nutritional risk index (GNRI) and International Society of Renal Nutrition and Metabolism (ISRNM) criteria. Multivariate logistic regression revealed independent risk factors for low FFMI and malnutrition. Of the patients, 47.4% had low FFMI. Patients with a reduction in FFMI tended to be older females with lower body mass index, SCI, and GNRI scores but significantly higher levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and IL-8. SCI was found to be an independent predictor for reduced FFMI (OR 0.57, 95% CI 0.40–0.81) and presence of PEW according to ISRNM criteria (OR 0.38, 95% CI 0.21–0.68). Although a positive association between systemic inflammatory markers and low FFMI was observed, this association disappeared in multivariate analysis. Moreover, the inflammatory markers examined in this study were not associated with malnutrition after adjusting for potential confounders. Compared with markers of systemic inflammation, SCI achieved better performance in assessing the nutritional status of hemodialysis patients.

Medical Director Practice of Advising Increased Dietary Protein Intake in Hemodialysis Patients With Hyperphosphatemia: Associations With Mortality in the Dialysis Outcomes and Practice Patterns Study

OBJECTIVES

Patients undergoing hemodialysis (HD) may have poor nutritional status and hyperphosphatemia. Nephrologists sometimes manage hyperphosphatemia by prescribing phosphate binders and/or recommending restriction of dietary phosphate including protein-rich foods; the later may, however, adversely affect nutritional status.

DESIGN AND METHODS

The analysis includes 8805 HD patients on dialysis ≥ 120 days in 12 countries in Dialysis Outcomes and Practice Patterns Study (DOPPS) phase 4 (2009-2011), from 248 facilities. The primary exposure variable was response to the following question: "For patients with serum albumin 3.0 g/dL and phosphate 6.0 mg/dL, do you recommend to (A) increase or (B) decrease/no change in dietary protein intake (DPI)?". The association between medical director's practice of recommending an increase in DPI and all-cause mortality was analyzed with Cox regression adjusted for potential confounders. Linear and logistic regressions were used to model the cross-sectional associations between DPI advice practice and intermediate markers of patient nutrition.

RESULTS

Median follow-up was 1.6 years. In the case scenario, 91% of medical directors in North America had a practice of recommending DPI increase compared to 58% in Europe (range = 36%-83% across 7 countries) and 56% in Japan. The practice of advising DPI increase was weakly associated with lower mortality [HR (95% CI): 0.88 (0.76-1.02)]. The association tended to be stronger in patients with age 70+ years [HR (95% CI): 0.82 (0.69-0.97), P = .12 for interaction]. The practice of advising DPI increase was associated with 0.276 mg/dL higher serum creatinine levels (95% CI: 0.033-0.520) after adjustment for case mix.

CONCLUSIONS

Medical director's practice of recommending an increase in DPI for HD patients with low albumin and high phosphate levels was associated with higher serum creatinine levels and potentially lower all-cause mortality. To recommend protein intake liberalization in parallel with phosphate management by physicians may be a critical practice for better nutritional status and outcomes in HD patients.