The effect of increasing dialysis dose in overweight hemodialysis patients on quality of life: a 6-week randomized crossover trial

The impact of dialysate flow rate on haemodialysis adequacy: a systematic review and meta-analysis

Background

Patients with kidney failure treated with maintenance haemodialysis (HD) require appropriate small molecule clearance. Historically, a component of measuring 'dialysis adequacy' has been quantified using urea kinetic modelling that is dependent on the HD prescription. However, the impact of dialysate flow rate on urea clearance remains poorly described in vivo and its influence on other patient-important outcomes of adequacy is uncertain.

Methods

We searched Embase, MEDLINE and the Cochrane Library from inception until April 2022 for randomized controlled trials and observational trials comparing a higher dialysate flow rate (800 ml/min) and lower dialysate flow rate (300 ml/min) with a standard dialysis flow rate (500 ml/min) in adults (age ≥18 years) treated with maintenance HD (>90 consecutive days). We conducted a random effects meta-analysis to estimate the pooled mean difference in dialysis adequacy as measured by Kt/V or urea reduction ratio (URR).

Results

A total of 3118 studies were identified. Of those, nine met eligibility criteria and four were included in the meta-analysis. A higher dialysate flow rate (800 ml/min) increased single-pool Kt/V by 0.08 [95% confidence interval (CI) 0.05-0.10, P < .00001] and URR by 3.38 (95% CI 1.97-4.78, P < .00001) compared with a dialysate flow rate of 500 ml/min. Clinically relevant outcomes including symptoms, cognition, physical function and mortality were lacking and studies were generally at a moderate risk of bias due to issues with randomization sequence generation, allocation concealment and blinding.

Conclusion

A higher dialysate flow increased urea-based markers of dialysis adequacy. Additional high-quality research is needed to determine the clinical, economic and environmental impacts of higher dialysate flow rates.

Measuring quality of life in trials including patients on haemodialysis: methodological issues surrounding the use of the Kidney Disease Quality of Life Questionnaire

BACKGROUND

Haemodialysis (HD) treatment causes a significant decrease in quality of life (QoL). When enrolled in a clinical trial, some patients are lost prior to follow-up because they die or they receive a kidney transplant. It is unclear how these patients are dealt with in the analysis of QoL data. There are questions surrounding the consistency of how QoL measures are used, reported and analysed.

METHODS

A systematic search of electronic databases for trials measuring QoL in HD patients using any variation of the Kidney Disease Quality of Life (KDQoL) Questionnaire was conducted. The review was conducted in Covidence version 2. Quantitative analysis was conducted in Stata version 16.

RESULTS

We included 61 trials in the review, of which 82% reported dropouts. The methods to account for missing data due to dropouts include imputation (7%) and complete case analysis (72%). Few trials (7%) conducted a sensitivity analysis to assess the impact of missing data on the study results. Single imputation techniques were used, but are only valid under strong assumptions regarding the type and pattern of missingness. There was inconsistency in the reporting of the KDQoL, with many articles (70%) amending the validated questionnaires or reporting only statistically significant results.

CONCLUSIONS

Missing data are not dealt with according to the missing data mechanism, which may lead to biased results. Inconsistency in the use of patient-reported outcome measures raises questions about the validity of these trials. Methodological issues in nephrology trials could be a contributing factor to why there are limited effective interventions to improve QoL in this patient group.

PROSPERO REGISTRATION

CRD42020223869.

The association of dialysis adequacy, body mass index, and mortality among hemodialysis patients

Background

Although hemodialysis (HD) adequacy, single-pool Kt/V_urea (spKt/V), is inversely correlated with body size, each is known to affect patient survival in the same direction. Therefore, we sought to examine the relationship between HD adequacy and mortality according to body mass index (BMI) in HD patients and explore a combination effect of BMI and HD adequacy on mortality risk.

Methods

We retrospectively reviewed patient data from the Korean Society of Nephrology registry, a nationwide database of medical records of HD patients, from January 2001 to June 2017. We included patients ≥18 years old who were receiving maintenance HD. Patients were categorized into three groups according to baseline BMI (< 20 (low), 20 to < 23 (normal), and ≥ 23 (high) kg/m²). Baseline spKt/V was divided into six categories.

Results

Among 18,242 patients on HD, the median follow-up duration was 5.2 (IQR, 1.9–8.9) years. Cox regression analysis showed that, compared to the reference (spKt/V 1.2–1.4), lower and higher baseline spKt/V were associated with greater and lower risks for all-cause mortality, respectively. However, among patients with high BMI (n = 5588), the association between higher spKt/V and lower all-cause mortality was attenuated in all adjusted models (P_interaction < 0.001). Compared to patients with normal BMI and spKt/V within the target range (1.2–1.4), those with low BMI had a higher risk for all-cause mortality at all spKt/V levels. However, the gap in mortality risk became narrower for higher values of spKt/V. Compared to patients with normal BMI and spKt/V in the target range, those with high BMI and spKt/V < 1.2 were not at increased risk for mortality despite low dialysis adequacy.

Conclusions

The association between spKt/V and mortality in HD patients may be modified by BMI.

Renal Association Clinical Practice Guideline on Haemodialysis

This guideline is written primarily for doctors and nurses working in dialysis units and related areas of medicine in the UK, and is an update of a previous version written in 2009. It aims to provide guidance on how to look after patients and how to run dialysis units, and provides standards which units should in general aim to achieve. We would not advise patients to interpret the guideline as a rulebook, but perhaps to answer the question: "what does good quality haemodialysis look like?"The guideline is split into sections: each begins with a few statements which are graded by strength (1 is a firm recommendation, 2 is more like a sensible suggestion), and the type of research available to back up the statement, ranging from A (good quality trials so we are pretty sure this is right) to D (more like the opinion of experts than known for sure). After the statements there is a short summary explaining why we think this, often including a discussion of some of the most helpful research. There is then a list of the most important medical articles so that you can read further if you want to - most of this is freely available online, at least in summary form.A few notes on the individual sections: 1. This section is about how much dialysis a patient should have. The effectiveness of dialysis varies between patients because of differences in body size and age etc., so different people need different amounts, and this section gives guidance on what defines "enough" dialysis and how to make sure each person is getting that. Quite a bit of this section is very technical, for example, the term "eKt/V" is often used: this is a calculation based on blood tests before and after dialysis, which measures the effectiveness of a single dialysis session in a particular patient. 2. This section deals with "non-standard" dialysis, which basically means anything other than 3 times per week. For example, a few people need 4 or more sessions per week to keep healthy, and some people are fine with only 2 sessions per week - this is usually people who are older, or those who have only just started dialysis. Special considerations for children and pregnant patients are also covered here. 3. This section deals with membranes (the type of "filter" used in the dialysis machine) and "HDF" (haemodiafiltration) which is a more complex kind of dialysis which some doctors think is better. Studies are still being done, but at the moment we think it's as good as but not better than regular dialysis. 4. This section deals with fluid removal during dialysis sessions: how to remove enough fluid without causing cramps and low blood pressure. Amongst other recommendations we advise close collaboration with patients over this. 5. This section deals with dialysate, which is the fluid used to "pull" toxins out of the blood (it is sometimes called the "bath"). The level of things like potassium in the dialysate is important, otherwise too much or too little may be removed. There is a section on dialysate buffer (bicarbonate) and also a section on phosphate, which occasionally needs to be added into the dialysate. 6. This section is about anticoagulation (blood thinning) which is needed to stop the circuit from clotting, but sometimes causes side effects. 7. This section is about certain safety aspects of dialysis, not seeking to replace well-established local protocols, but focussing on just a few where we thought some national-level guidance would be useful. 8. This section draws together a few aspects of dialysis which don't easily fit elsewhere, and which impact on how dialysis feels to patients, rather than the medical outcome, though of course these are linked. This is where home haemodialysis and exercise are covered. There is an appendix at the end which covers a few aspects in more detail, especially the mathematical ideas. Several aspects of dialysis are not included in this guideline since they are covered elsewhere, often because they are aspects which affect non-dialysis patients too. This includes: anaemia, calcium and bone health, high blood pressure, nutrition, infection control, vascular access, transplant planning, and when dialysis should be started.

Reporting of "dialysis adequacy" as an outcome in randomised trials conducted in adults on haemodialysis

Background

Clinical trials are most informative for evidence-based decision-making when they consistently measure and report outcomes of relevance to stakeholders, especially patients, clinicians, and policy makers. However, sometimes terminology used is interpreted differently by different stakeholders, which might lead to confusion during shared decision making. The construct dialysis adequacy is frequently used, suggesting it is an important outcome both for health care professionals as for patients.

Objective

To assess the scope and consistency of the construct dialysis adequacy as reported in randomised controlled trials in hemodialysis, and evaluate whether these align to the insights and understanding of this construct by patients.

Methods

To assess scope and consistency of dialysis adequacy by professionals, we performed a systematic review searching the Cochrane Central Register of Controlled Trials (CENTRAL) up to July 2017. We identified all randomised controlled trails (RCT) including patients on hemodialysis and reporting dialysis adequacy, adequacy or adequacy of dialysis and extracted and classified all reported outcomes. To explore interpretation and meaning of the construct of adequacy by patients, we conducted 11 semi-structured interviews with HD patients using thematic analysis. Belgian registration number B670201731001.

Findings

From the 31 included trials, we extracted and classified 98 outcome measures defined by the authors as adequacy of dialysis, of which 94 (95%) were biochemical, 3 (3%) non-biochemical surrogate and 2 (2%) patient-relevant. The three most commonly reported measures were all biochemical. None of the studies defined adequacy of dialysis as a patient relevant outcome such as survival or quality of life. Patients had a substantially different understanding of the construct dialysis adequacy than the biochemical interpretation reported in the literature. Being alive, time spent while being on dialysis, fatigue and friendliness of staff were the most prominent themes that patients linked to the construct of dialysis adequacy.

Conclusion

Adequacy of dialysis as reported in the literature refers to biochemical outcome measures, most of which are not related with patient relevant outcomes. For patients, adequate dialysis is a dialysis that enables them to spend as much quality time in their life as possible.

Frailty, Health-Related Quality of Life, Cognition, Depression, Vitamin D and Health-Care Utilization in an Ambulatory Adult Population With Type 1 or Type 2 Diabetes Mellitus and Chronic Kidney Disease: A Cross-Sectional Analysis

OBJECTIVES

Frailty can cause increased vulnerability to adverse health outcomes, such as falls, fractures, depression and reduced health-related quality of life (HRQoL). This cross-sectional study compared the differences in body composition, HRQoL, mental health and cognitive and vitamin D (vitD) status with health-care utilization by frail and nonfrail adults with diabetes mellitus (type 1 and type 2) and with chronic kidney disease (stages 1 through 5).

METHODS

We studied adults with type 1 and type 2 diabetes and chronic kidney disease stages 1 through 5 who were participating in a longitudinal follow-up study (41 to 83 years of age; n=41). Body composition (dual-energy x-ray absorptiometry); vitD status (serum 25[OH]D₃); frailty (Edmonton Frail Scale); depression (Major Depression Inventory); HRQoL (Short Form Health Survey-36); and cognitive status (Mini Mental State exam) were measured using validated tools. Participants who were on dialysis and had body weights >136 kg, and coinciding comorbidities known to influence vitD metabolism were excluded.

RESULTS

Frailty occurred in 17% of participants (n=7). Frail participants had lower lean body mass, lower HRQoL scores (individual and composite scores), more depression (p=<0.05) and higher numbers of health visits (total, inpatient and emergency) compared with nonfrail participants (p<0.05). No differences in health-care visit types or vitD status were noted between frail and nonfrail participants (p>0.05).

CONCLUSIONS

Frailty in an ambulatory population of adults with chronic kidney disease and diabetes is associated with low lean body mass, low HRQoL, greater depression and higher numbers of health-care visits.

Prognostic Value of the Delivery Dialysis Dose on Twice-Weekly Hemodialysis Patients

BACKGROUND

Few studies have evaluated the prognostic value of dialysis dose in twice-weekly hemodialysis (HD). A single-pool Kt/V (spKt/V) over 1.70 may benefit patients receiving twice-weekly maintenance HD.

METHODS

This is a multicenter randomized controlled trial performed on 163 patients from 17 dialysis centers in Shanghai who were allocated to high- (n = 98) and standard-dose groups (n = 65) and followed through 96 weeks of study period. Therapeutic approaches were given to increase spKt/V to over 1.70 in the high-dose group. Data were collected every 12-24 weeks. The primary outcomes were all-cause mortality and major adverse cardio-cerebrovascular events (MACEs) occurrence, and secondary outcomes included residual kidney function (RKF) and health-related quality of life (HR-QOL).

RESULTS

The spKt/V in high-dose and standard-dose groups were 1.80 ± 0.23 and 1.55 ± 0.19, respectively, after an 8-week intervention (p < 0.001). At the end of the study, SF-36 physical function and total score in high-dose group were 82 (69-90) and 74 (47-84), respectively, both of which were higher than those in the standard-dose group. Decline in urine volume was observed in both groups with no significant difference (p = 0.431). No difference was found in overall survival between the 2 groups (p = 0.580). The 1-year MACE-free survival for high-dose group was 84.49%, better than 76.72% for standard-dose group (p = 0.029).

CONCLUSIONS

Higher spKt/V is also associated with MACE-free survival and better HR-QOL, especially in physical function aspect for twice-weekly dialysis patients. Increasing spKt/V over 1.70 in twice-weekly HD population does not cause loss of RKF.

Timing of dialysis initiation, duration and frequency of hemodialysis sessions, and membrane flux: a systematic review for a KDOQI clinical practice guideline

BACKGROUND

In 2006, NKF-KDOQI (National Kidney Foundation-Kidney Disease Outcomes Quality Initiative) published clinical practice guidelines for hemodialysis adequacy. Recent studies evaluating hemodialysis adequacy as determined by initiation timing, frequency, duration, and membrane type and prompted an update to the guideline.

STUDY DESIGN

Systematic review and evidence synthesis.

SETTING & POPULATION

Patients with advanced chronic kidney disease receiving hemodialysis.

SELECTION CRITERIA FOR STUDIES

We screened publications from 2000 to March 2014, systematic reviews, and references and consulted the NKF-KDOQI Hemodialysis Adequacy Work Group members. We included randomized or controlled clinical trials in patients undergoing long-term hemodialysis if they reported outcomes of interest.

INTERVENTIONS

Early versus late dialysis therapy initiation; more frequent (>3 times a week) or longer duration (>4.5 hours) compared to conventional hemodialysis; low- versus high-flux dialyzer membranes.

OUTCOMES

All-cause and cardiovascular mortality, myocardial infarction, stroke, hospitalizations, quality of life, depression or cognitive function scores, blood pressure, number of antihypertensive medications, left ventricular mass, interdialytic weight gain, and harms or complications related to vascular access or the process of dialysis.

RESULTS

We included 32 articles reporting on 19 trials. Moderate-quality evidence indicated that earlier dialysis therapy initiation (at estimated creatinine clearance [eClcr] of 10-14mL/min) did not reduce mortality compared to later initiation (eClcr of 5-7mL/min). More than thrice-weekly hemodialysis and extended-length hemodialysis during a short follow-up did not improve clinical outcomes compared to conventional hemodialysis and resulted in a greater number of vascular access procedures (very low-quality evidence). Hemodialysis using high-flux membranes did not reduce all-cause mortality, but reduced cardiovascular mortality compared to hemodialysis using low-flux membranes (moderate-quality evidence).

LIMITATIONS

Few studies were adequately powered to evaluate mortality. Heterogeneity of study designs and interventions precluded pooling data for most outcomes.

CONCLUSIONS

Limited data indicate that earlier dialysis therapy initiation and more frequent and longer hemodialysis did not improve clinical outcomes compared to conventional hemodialysis.

"Vitamin D supplementation and bone health in adults with diabetic nephropathy: the protocol for a randomized controlled trial"

BACKGROUND

Suboptimal vitamin D status is highly prevalent in Northern communities, particularly in those patients with chronic diseases such as diabetes and chronic renal disease. Emerging literature suggests that adherence to daily vitamin D supplementation may be an important factor influencing vitamin D status and overall bone health, but compliance with therapies for bone health is a major challenge. It is unknown what level of vitamin D supplementation will ameliorate or improve suboptimal vitamin D status in patients with diabetic nephropathy or contribute to improved bone health, particularly for those living in northern climates.

METHODS/DESIGN

The study purpose was to examine two different strategies of vitamin D3 supplementation; daily dosing of 2000 IU per day verses monthly dosing of 40,000 IU per month on markers of vitamin D status, bone health and to examine whether adherence, quality of life and patient satisfaction with the supplementation strategy differs between the two vitamin D strategies in adults diagnosed with diabetic nephropathy.

DISCUSSION

The need for RCTs assessing higher doses of vitamin D3 supplementation at varying frequencies of administration and its impact on bone health in adults with diabetes and chronic kidney disease are needed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01476501.

High-flux versus low-flux membranes for end-stage kidney disease

BACKGROUND

Clinical practice guidelines regarding the use of high-flux haemodialysis membranes vary widely.

OBJECTIVES

We aimed to analyse the current evidence reported for the benefits and harms of high-flux and low-flux haemodialysis.

SEARCH METHODS

We searched Cochrane Renal Group's specialised register (July 2012), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1948 to March 2011), and EMBASE (1947 to March 2011) without language restriction.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared high-flux haemodialysis with low-flux haemodialysis in people with end-stage kidney disease (ESKD) who required long-term haemodialysis.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two authors for study characteristics (participants and interventions), risks of bias, and outcomes (all-cause mortality and cause-specific mortality, hospitalisation, health-related quality of life, carpal tunnel syndrome, dialysis-related arthropathy, kidney function, and symptoms) among people on haemodialysis. Treatment effects were expressed as a risk ratio (RR) or mean difference (MD), with 95% confidence intervals (CI) using the random-effects model.

MAIN RESULTS

We included 33 studies that involved 3820 participants with ESKD. High-flux membranes reduced cardiovascular mortality (5 studies, 2612 participants: RR 0.83, 95% CI 0.70 to 0.99) but not all-cause mortality (10 studies, 2915 participants: RR 0.95, 95% CI 0.87 to 1.04) or infection-related mortality (3 studies, 2547 participants: RR 0.91, 95% CI 0.71 to 1.14). In absolute terms, high-flux membranes may prevent three cardiovascular deaths in 100 people treated with haemodialysis for two years. While high-flux membranes reduced predialysis beta-2 microglobulin levels (MD -12.17 mg/L, 95% CI -15.83 to -8.51 mg/L), insufficient data were available to reliably estimate the effects of membrane flux on hospitalisation, carpal tunnel syndrome, or amyloid-related arthropathy. Evidence for effects of high-flux membranes was limited by selective reporting in a few studies. Insufficient numbers of studies limited our ability to conduct subgroup analyses for membrane type, biocompatibility, or reuse. In general, the risk of bias was either high or unclear in the majority of studies.

AUTHORS' CONCLUSIONS

High-flux haemodialysis may reduce cardiovascular mortality in people requiring haemodialysis by about 15%. A large well-designed RCT is now required to confirm this finding.