Pre-dilution haemofiltration--the Sardinian multicentre studies: present and future. The Sardinian Collaborative Study Group on Haemofiltration On-Line

Effect of online hemodiafiltration compared with hemodialysis on quality of life in patients with ESRD: A systematic review and meta-analysis of randomized trials

Background

End-stage renal disease (ESRD) is related to high morbidity, mortality, and impaired health-related quality of life. While hemodialysis (HD) is the current life-saving standard of treatment for patients with ESRD, their quality of life (QoL) remains far from desirable. Online HDF (OL-HDF), due to its convenience, could improve the QoL of patients with ESRD, however, this remains uncertain.

Objective

We aimed to assess the body of evidence of OL-HDF compared to HD regarding QoL in patients with ESRD.

Methods

We comprehensively searched in multiple data bases from their inception to February 2018. Reviewers working independently and in duplicate appraised the quality and included randomized controlled trials (RCTs) that evaluated, in patients with ESRD and HD or OL-HDF, QoL (Short Form Health Survey with 36 questions (SF-36) with physical component score (PCS) and mental component score (MCS) as well as scores about social activity, fatigue, and emotion). A meta-analysis of each outcome of interest was performed using a random-effects model.

Results

Six moderate quality RCTs met the inclusion criteria. Meta-analysis of 4 RCTs including a total of 1,209 patients showed that OL-HDF was associated with a lower yet non-significant score of PCS: MD (mean difference) -0.77 (95% CI -1.94 to 0.41, p = 0.20), and MCS: MD -1.25 (95% CI -3.10 to 0.59, p = 0.18); indicating a poorer QoL in patients on OL-HDF. Meta-analysis of 4 RCTs including a total of 845 patients showed OL-HDF was associated with a significant increase in the score of social activity compared to HD: SMD (standardized mean difference): 1.95 (95% CI 0.05 to 3.86, p = 0.04), indicating a better QoL in patients on OL-HDF; but regarding fatigue and emotion, there was no significant improvement when compared to HD by meta-analysis of 3 RCTs (133 patients).

Conclusions

The body of evidence suggests that OL-HDF does not improve QoL in patients with ESRD when compared to HD.

Haemodiafiltration, haemofiltration and haemodialysis for end-stage kidney disease

BACKGROUND

Convective dialysis modalities (haemofiltration (HF), haemodiafiltration (HDF), and acetate-free biofiltration (AFB)) removed excess body fluid across the dialysis membrane with positive pressure and accumulated middle- and larger-size accumulated solutes more efficiently than haemodialysis (HD). This increased larger solute removal combined with use of ultra-pure dialysis fluid in convective dialysis is hypothesised to reduce the frequency and severity of symptoms during dialysis as well as improve clinical outcomes. Convective dialysis therapies (HDF and HF) are associated with lower mortality compared to diffusive therapy (HD) in observational studies. This is an update of a review first published in 2006.

OBJECTIVES

To compare convective (HF, HDF, or AFB) with diffusive (HD) dialysis modalities on clinical outcomes (mortality, major cardiovascular events, hospitalisation and treatment-related adverse events) in men and women with end-stage kidney disease (ESKD).

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register (to 18 February 2015) through contact with a Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials comparing convective therapy (HF, HDF, AFB) with another convective therapy or diffusive therapy (HD) for treatment of ESKD.

DATA COLLECTION AND ANALYSIS

Two independent authors identified studies, extracted data and assessed study risk of bias. We summarised treatment effects using the random effects model. We reported results as a risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous data together with 95% confidence intervals (CI). We assessed for heterogeneity using the Chi(2) test and explored the amount of variation in treatment estimates beyond that expected by chance using the I(2) statistic.

MAIN RESULTS

Twenty studies comprising 667 participants were included in the 2006 review. In that review, there was insufficient evidence of treatment effects on major clinical outcomes to draw clinically meaningful conclusions. Searching to February 2015 identified 40 eligible studies comprising 3483 participants overall. In total, 35 studies (4039 participants) compared HF, HDF or AFB with HD, three studies (54 participants) compared AFB with HDF, and three studies (129 participants) compared HDF with HF.Risks of bias in all studies were generally high resulting in low confidence in estimated treatment effects. Convective dialysis had no significant effect on all-cause mortality (11 studies, 3396 participants: RR 0.87, 95% CI 0.72 to 1.05; I(2) = 34%), but significantly reduced cardiovascular mortality (6 studies, 2889 participants: RR 0.75, 95% CI 0.61 to 0.92; I(2) = 0%). One study reported no significant effect on rates of nonfatal cardiovascular events (714 participants: RR 1.14, 95% CI 0.86 to 1.50) and two studies showed no significant difference in hospitalisation (2 studies, 1688 participants: RR 1.23, 95% CI 0.93 to 1.63; I(2) = 0%). One study reported rates of hypotension during dialysis were significantly reduced with convective therapy (906 participants: RR 0.72, 95% CI 0.66 to 0.80). Adverse events were not systematically evaluated in most studies and data for health-related quality of life were sparse. Convective therapies significantly reduced predialysis levels of B2 microglobulin (12 studies, 1813 participants: MD -5.55 mg/dL, 95% CI -9.11 to -1.98; I(2) = 94%) and increased dialysis dose (Kt/V urea) (14 studies, 2022 participants: MD 0.07, 95% CI -0.00 to 0.14; I(2) = 90%) compared to diffusive therapy, but results across studies were very heterogeneous. Sensitivity analyses limited to studies comparing HDF with HD showed very similar results. Directly comparative data for differing types of convective dialysis were insufficient to draw conclusions.Studies had important risks of bias leading to low confidence in the summary estimates and were generally limited to patients who had adequate dialysis vascular access.

AUTHORS' CONCLUSIONS

Convective dialysis may reduce cardiovascular but not all-cause mortality and effects on nonfatal cardiovascular events and hospitalisation are inconclusive. However, any treatment benefits of convective dialysis on all patient outcomes including cardiovascular death are unreliable due to limitations in study methods and reporting. Future studies which assess treatment effects of convection dose on patient outcomes including mortality and cardiovascular events would be informative.

Haemodiafiltration, haemofiltration and haemodialysis for end-stage kidney disease

BACKGROUND

Renal replacement therapy (RRT) for end-stage kidney disease (ESKD) can be achieved by several interventions including haemodialysis (HD), peritoneal dialysis (PD) and kidney transplantation. HD, haemofiltration (HF), haemodiafiltration (HDF) and acetate-free biofiltration (AFB) are extracorporeal RRT methods. It has been suggested that HF and HDF may reduce the frequency and severity of intradialytic and post-dialytic adverse symptoms and may be more effective than HD in the removal of high molecular weight molecules.

OBJECTIVES

To compare convective modes of extracorporeal RRT (HF, HDF or AFB) with HD and to establish if any of these techniques is superior to each other in patients with ESKD.

SEARCH STRATEGY

We searched MEDLINE (1966-2006), EMBASE (1980-2006), Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library issue 2, 2006) and CINAHL (1872-2006). Authors of included studies were contacted, reference lists of identified RCTs and relevant narrative reviews were screened.

SELECTION CRITERIA

RCTs comparing HF, HDF, AFB and HD for ESKD were included. Trials enrolling any patient undergoing RRT for ESKD were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) for dichotomous outcomes or weighted mean difference (MD) for continuous data with 95% confidence intervals (CI). Heterogeneity was measured using the Chi-square (chi(2)) and I(2) statistic.

MAIN RESULTS

Twenty studies (657 patients) were included. Seventeen studies compared HF, HDF or AFB with HD, two compared HDF with AFB and one compared HF with HDF. The studies were generally small with suboptimal quality. Convective modalities (HF, HDF, AFB) did not differ significantly from HD for mortality (RR 1.68, 95% CI 0.23 to 12.13; chi(2)= 2.58, P = 0.11, I(2) = 61.2%), number of hospital admissions/year (MD 0.20, 95% CI -0.07 to 0.47) and dialysis adequacy (Kt/V: MD 0.09, 95% CI 0.02 to 0.17; chi(2) = 3.73, P = 0.29, I(2) = 19.6%). No study assessed number of dialysis treatments associated with "any adverse symptoms", sessions that were stopped early, change of dialysis modality or dialysis-related amyloidosis.

AUTHORS' CONCLUSIONS

We were unable to demonstrate whether convective modalities (either HF, HDF or AFB) have significant advantages over HD with regard to clinically important outcomes of mortality, dialysis-related hypotension and hospitalisation. More adequately-powered good quality RCTs assessing clinically important outcomes (mortality, hospitalisation, quality of life) are needed.

The hemodynamic effect of calcium ion concentration in the infusate during predilution hemofiltration in chronic renal failure

BACKGROUND

It is the prevailing view that convective dialysis techniques stabilize blood pressure. Calcium concentration in the substitution fluid may be important in this respect. The aim of this study is to investigate the influence of calcium ion concentration in the substitution fluid on hemodynamic stability during predilution hemofiltration (HF).

METHODS

We conducted a randomized, crossover, blinded, controlled trial with 12 stable long-term hemodialysis patients without diabetes. Each patient was randomly assigned to substitution fluid with a calcium ion (iCa) concentration of 2.5 mEq/L (1.25 mmol/L; low-calcium session [L-HF]) or 3.5 mEq/L (1.75 mmol/L; high-calcium session [H-HF]) during 4.5 hours of predilution HF with a volume of 1.24 +/- 0.09 L/kg dry body weight and a temperature of 37 degrees C. Ultrafiltration was kept constant in each patient. Blood pressure (mean, systolic [SBP], and diastolic blood pressure [DBP]), pulse rate, arterial and venous temperature, energy transfer, and relative blood volume were measured at 15-minute intervals. Cardiac output, total peripheral resistance, stroke volume, and iCa were measured hourly. The 2 treatments were matched with the exception of iCa concentration.

RESULTS

A significant intratreatment reduction in cardiac output and stroke volume was shown to the same extent for both groups. Intertreatment comparisons showed a significantly lower mean arterial pressure, SBP, DBP, and total peripheral resistance in the L-HF compared with the H-HF group.

CONCLUSION

iCa concentration of 3.5 versus 2.5. mEq/L (1.75 versus 1.25 mmol/L) in the infusate during predilution HF stabilized blood pressure, possibly because of greater peripheral resistance rather than through changes in cardiac performance.

Comparison of hemodialysis, hemofiltration, and acetate-free biofiltration for ESRD: systematic review

BACKGROUND

We performed a systematic review of randomized controlled trials (RCTs) comparing hemodialysis (HD), hemofiltration (HF), hemodiafiltration (HDF), and acetate-free biofiltration (AFB) in the treatment of patients with end-stage renal disease to assess their clinical effectiveness.

METHODS

The Cochrane CENTRAL Registry, MEDLINE, EMBASE, CINAHL, the American College of Physicians Database, Database of Abstracts of Reviews of Effectiveness, and reference lists were searched for randomized trials of HF, HDF, and AFB compared with HD; HDF compared with AFB; and HF compared with HDF. Two reviewers extracted data for all-cause mortality; hypotension, headache, nausea, vomiting, and any other adverse symptoms; quality of life (QoL); hospitalization; dialysis adequacy; and end-of-treatment beta 2 -microglobulin levels. Analysis was by means of a random-effects model, and results are expressed as relative risk (RR) and weighted mean difference (WMD) with 95% confidence intervals (CIs).

RESULTS

Eighteen eligible trials (588 patients) were identified. HDF was associated with significantly greater mortality risk than HD (4 trials, 326 patients; RR, 3.52; 95% CI, 1.37 to 9.47). Risk for mortality was not different among the other comparisons. Risks for hypotension episodes and dialysis-related symptoms were not significantly different with HD, HF, HDF, and AFB (18 trials, 583 patients). QoL, assessed by using an unvalidated scoring tool, appeared to be significantly improved in patients on HDF therapy than those on HD therapy (1 trial, 67 patients; WMD, 0.6; 95% CI, 0.3 to 0.9), but this was not evident when validated QoL assessment tools were used. Use of AFB compared with HDF was not associated with a significant difference in risk for hospitalization (1 trial, 11 patients; WMD, -0.45; 95% CI, -1.42 to 0.52). HDF in comparison to HD did not reduce the risk for carpal tunnel syndrome (1 trial, 67 patients; RR, 2.04; 95% CI, 0.59 to 7.00). Kt/V was significantly different with HDF compared with HD (3 trials, 124 patients; WMD, 0.14; 95% CI, 0.05 to 0.22). No other substantial data for these interventions and their impact on major patient-centered outcomes were available.

CONCLUSION

The trials assessed were not powered adequately and had suboptimal method quality. It is not possible on the basis of effectiveness to prefer one extracorporeal renal replacement therapy modality to the other for end-stage kidney disease because significant differences in clinically important outcomes have not been shown by available published RCTs.

Predilution hemodiafiltration displays no hemodynamic advantage over low-flux hemodialysis under matched conditions

BACKGROUND

It is the prevailing view that convective dialysis techniques stabilize blood pressure. The aim of this study was to compare the intrasession hemodynamics during high-dose predilution hemodiafiltration (HDF) and low-flux hemodialsis, under strict controlled conditions.

METHODS

Twelve stable hemodialysis patients were investigated in a randomized crossover blinded controlled trial. The patients were allocated to one session of predilution HDF (substitution fluid 1.20 +/- 0.10 L/kg body weight) and one session of hemodialysis at 4(1/2) hours. To eliminate confounding factors, dialysis dose, ultrafiltration volume and arterial temperature were matched. At the start of the dialysis the patients' core temperature was "locked" by an automatic feedback system regulating the dialysate temperature; thereby, patients' temperature was kept stable throughout the whole treatment. The calcium-ion concentration in the substitution/dialysis fluid was 1.25 mmol/L. Cardiac output was measured hourly by the ultrasound velocity dilution method.

RESULTS

Mean blood pressure, cardiac output, stroke volume, cardiac work, and relative blood volume was significantly reduced in both treatments. Total peripheral resistance increased significantly in both groups. Ultrafiltration volume, cardiopulmonary recirculation, Kt/V, and total energy transfer were similar for hemodialysis and HDF. The pulse rate showed no significant change throughout both sessions. No significant differences were revealed between hemodialysis and HDF.

CONCLUSION

The hemodynamics of predilution HDF and low-flux hemodialysis displayed a similar profile during matched conditions. An acute circulatory benefit of convective solute removal over diffusive could not be demonstrated.

Daily Hemofiltration for End-Stage Renal Disease: A Feasibility and Efficacy Trial

BACKGROUND

Although conventional hemodialysis (CHD) is currently provided primarily on an intermittent basis for patients with end-stage renal diseases (ESRD), the value of daily dialysis is well documented. Daily hemofiltration (DHF) is a convective therapy that has received little attention as an alternative to CHD. The aim of this feasibility study was to validate and assess the efficacy of DHF (6 times/week) as an alternative to CHD (3 times/week) in patients with ESRD.

METHODS

In this prospective single-arm open-labeled study, DHF was administered over 4 weeks after a 1-week run-in phase period of CHD. Blood samples were drawn at baseline and on a weekly basis during the trial, and ultrafiltrate samples were collected weekly during the DHF period. The primary endpoint was to achieve a daily spKt/V of 0.40 (equivalent to a weekly stdKt/V of approximately 2.0). To achieve this goal, the DHF prescription consisted of an exchange volume of 40% of total body water. Secondary endpoints were the evaluation of blood pressure and anemia parameters, nutritional and mineral metabolism markers and health-related quality of life measures.

RESULTS

Twelve patients completed the study. Mean age was 54 years, two-thirds were men, and 83% had arteriovenous fistulae. DHF delivered a mean (+/-SD) spKt/V of 0.44 +/- 0.06. This goal was reached by delivering an exchange volume of 13-14 liters, consisting of a replacement fluid volume of 11.7 +/- 1.9 l/session and net fluid loss of 1.4 +/- 0.1 l/session. Conversion from CHD to DHF resulted in marked reduction in treatment time (3.8 vs. 2 h/session, p < 0.001) and net fluid loss (2.6 vs. 1.4 l/session, p < 0.001). Calculated weekly standard Kt/V during the last week of DHF was 1.9 +/- 0.2. DHF achieved a median beta2-microglobulin (beta2-M) removal of 170 mg/session, resulting in a decrease of mid-week pre-therapy beta2-M levels (48 +/- 34 vs. 36 +/- 25 mg/l, p = 0.07). Compared with CHD, DHF resulted in lower systolic (143 +/- 19 vs. 133 +/- 16 mm Hg, p = 0.002) and diastolic (79 +/- 11 vs. 72 +/- 12 mm Hg, p = 0.002) blood pressure, reduction in antihypertensive medications (2.1 +/- 0.7 vs. 1.1 +/- 0.8, p = 0.002), higher caloric intake (1,778 +/- 441 vs. 2,044 +/- 564 kcal/day, p = 0.01), higher normalized protein catabolic rate (0.88 +/- 0.17 vs. 1.00 +/- 0.35 g/kg/day, p = 0.05), higher pre-albumin levels (330 +/- 50 vs. 378 +/- 84 g/dl, p = 0.06), higher vitality (p = 0.02), improved cognitive function (p = 0.04) and less symptoms/problems (p = 0.03). Serum albumin and potassium levels remained unchanged but the serum bicarbonate level dropped during the 1-month period of DHF.

CONCLUSIONS

DHF (6 times/week) over a 1-month period achieved a weekly stdKt/V of approximately 2.0, which is similar to that recommended for 3 times weekly CHD, reduced beta2-M levels, lowered blood pressure, and had some beneficial effect on nutritional parameters, and health-related quality of life measures.

A time for rediscovery: chronic hemofiltration for end-stage renal disease

Provision of maintenance renal replacement therapy (MRRT) is becoming increasingly challenging. The number of patients requiring MRRT is growing rapidly, while the number of nephrologists, nurses, and other staff available to provide therapy is not increasing at a similar rate. Patients are now older and have more comorbid conditions, which magnifies the complexity of their RRT and makes it increasingly difficult to maintain the quality of care within the limitations of constrained economic resources. The two most commonly used MRRTs are hemodialysis (HD) and peritoneal dialysis (PD). A third modality of MRRT, hemofiltration, is not currently in widespread use in North America. In hemofiltration, plasma is filtered through a highly permeable, biocompatible synthetic membrane and waste products are removed by convection and solvent drag as the filtrate moves across the membrane. Hemofiltration equipment constantly monitors the rate of plasma removal and administers a sterile, nonpyrogenic replacement solution at an appropriate rate to replace the waste-laden ultrafiltrate and avoid vdume depletion in the patient. Hemofiltration may offer some potential clinical advantages to the MRRT patient, including better hemodynamic and cardiovascular stability, enhanced removal of middle molecular weight toxins, increased comfort, and therapy preference. Some reports indicate possible reduced morbidity and mortality and reduced risk of bacterial contamination and inflammation as a result of the use of sterile, ultrapure replacement fluids. Chronic hemofiltration is a relatively simple MRRT option that may offer significant benefits for many patients who have end-stage renal disease (ESRD) and deserves closer consideration for these patients.