Intima-media thickness at the near or far wall of the common carotid artery in cardiovascular risk assessment

Aims

Current guidelines recommend measuring carotid intima-media thickness (IMT) at the far wall of the common carotid artery (CCA). We aimed to precisely quantify associations of near vs. far wall CCA-IMT with the risk for atherosclerotic cardiovascular disease (CVD, defined as coronary heart disease or stroke) and their added predictive values.

Methods and results

We analysed individual records of 41 941 participants from 16 prospective studies in the Proof-ATHERO consortium {mean age 61 years [standard deviation (SD) = 11]; 53% female; 16% prior CVD}. Mean baseline values of near and far wall CCA-IMT were 0.83 (SD = 0.28) and 0.82 (SD = 0.27) mm, differed by a mean of 0.02 mm (95% limits of agreement: -0.40 to 0.43), and were moderately correlated [r = 0.44; 95% confidence interval (CI): 0.39-0.49). Over a median follow-up of 9.3 years, we recorded 10 423 CVD events. We pooled study-specific hazard ratios for CVD using random-effects meta-analysis. Near and far wall CCA-IMT values were approximately linearly associated with CVD risk. The respective hazard ratios per SD higher value were 1.18 (95% CI: 1.14-1.22; I² = 30.7%) and 1.20 (1.18-1.23; I² = 5.3%) when adjusted for age, sex, and prior CVD and 1.09 (1.07-1.12; I² = 8.4%) and 1.14 (1.12-1.16; I²=1.3%) upon multivariable adjustment (all P < 0.001). Assessing CCA-IMT at both walls provided a greater C-index improvement than assessing CCA-IMT at one wall only [+0.0046 vs. +0.0023 for near (P < 0.001), +0.0037 for far wall (P = 0.006)].

Conclusions

The associations of near and far wall CCA-IMT with incident CVD were positive, approximately linear, and similarly strong. Improvement in risk discrimination was highest when CCA-IMT was measured at both walls.

Long-term peridialytic blood pressure changes are related to mortality

BACKGROUND

In chronic haemodialysis (HD) patients, the relationship between long-term peridialytic blood pressure (BP) changes and mortality has not been investigated.

METHODS

To evaluate whether long-term changes in peridialytic BP are related to mortality and whether treatment with HD or haemodiafiltration (HDF) differs in this respect, the combined individual participant data of three randomized controlled trials comparing HD with HDF were used. Time-varying Cox regression and joint models were applied.

RESULTS

During a median follow-up of 2.94 years, 609 of 2011 patients died. As for pre-dialytic systolic BP (pre-SBP), a severe decline (≥21 mmHg) in the preceding 6 months was independently related to increased mortality [hazard ratio (HR) 1.61, P = .01] when compared with a moderate increase. Likewise, a severe decline in post-dialytic diastolic BP (DBP) was associated with increased mortality (adjusted HR 1.96, P < .0005). In contrast, joint models showed that every 5-mmHg increase in pre-SBP and post-DBP during total follow-up was related to reduced mortality (adjusted HR 0.97, P = .01 and 0.94, P = .03, respectively). No interaction was observed between BP changes and treatment modality.

CONCLUSION

Severe declines in pre-SBP and post-DBP in the preceding 6 months were independently related to mortality. Therefore peridialytic BP values should be interpreted in the context of their changes and not solely as an absolute value.

Physical intradialytic patient-reported outcome measures in haemodialysis and haemodiafiltration: A cross-over study

AIM

Standard haemodialysis (sHD) is associated with a poor survival and marked adverse intradialytic patient-reported outcome measures (ID-PROMs). Whereas physical ID-PROMs (PID-PROMs) are alleviated by cool dialysate (cHD), survival is prolonged by haemodiafiltration (HDF). So far, PID-PROMs are not prospectively compared between HD and HDF.

METHODS

To assess whether PID-PROMs and thermal perception differ between sHD, cHD, low volume HDF (lvHDF) and high volume HDF (hvHDF), 40 patients were cross-over randomized to each modality for 2 weeks. Dialysate temperature (T_d ) was 36.5°C, except in cHD (T_d 35.5°C). Target convection volumes were 15 L in lvHDF and ≥ 23 L in hvHDF. PID-PROMs were evaluated with a modified Dialysis Symptom Index (mDSI) and thermal perception with the Visual Analogue Scale Thermal Perception (VAS-TP). T_b and room temperature were measured as well.

RESULTS

Except for the item 'feeling cold' during cHD (p = .01), PID-PROMs did not differ between modalities, but varied markedly between patients (11/13 items, p < .05). T_b increased in sHD, lvHDF, and hvHDF (+0.30, 0.35, 0.38°C, respectively, all p < .0005), but remained stable in cHD (+0.04°C, p = .43). Thermal perception remained unaltered in sHD and both HDF modalities, but shifted towards cold in cHD (p = .007).

CONCLUSION

(1) PID-PROMs did not differ between modalities, but varied markedly between patients. Hence, PID-PROMs are largely patient-dependent. (2) While T_b increased in sHD, lvHDF and hvHDF, thermal perception did not change. Yet, whereas T_b remained unaltered in cHD, cold perception emerged. Hence, as for bothersome cold sensations, cHD should be avoided in perceptive individuals.

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.

Why and how high volume hemodiafiltration may reduce cardiovascular mortality in stage 5 chronic kidney disease dialysis patients? A comprehensive literature review on mechanisms involved

Online hemodiafiltration (HDF) is an established renal replacement modality for patients with end stage chronic kidney disease that is now gaining rapid clinical acceptance worldwide. Currently, there is a growing body of evidence indicating that treatment with HDF is associated with better outcomes and reduced cardiovascular mortality for dialysis patients. In this comprehensive review, we provide an update on the potential mechanisms which may improve survival in HDF treated patients. The strongest evidence is for better hemodynamic stability and reduced endothelial dysfunction associated with HDF treatments. Clinically, this is marked by a reduced incidence of intradialytic hypotensive episodes, with a better hemodynamic response to ultrafiltration, mediated by an increase in total peripheral vascular resistance and extra-vascular fluid recruitment, most likely driven by the negative thermal balance associated with online HDF therapy. In addition, endothelial function appears to be improved due to a combination of a reduction of the inflammatory and oxidative stress complex syndrome and exposure to circulating cardiovascular uremic toxins. Reports of reversed cardiovascular remodeling effects with HDF may be confounded by volume and blood pressure management, which are strongly linked to center clinical practices. Currently, treatment with HDF appears to improve the survival of dialysis patients predominantly due to a reduction in their cardiovascular burden, and this reduction is linked to the sessional convection volume exchanged.

Effect of various dialysis modalities on intradialytic hemodynamics, tissue injury and patient discomfort in chronic dialysis patients: design of a randomized cross-over study (HOLLANT)

BACKGROUND

From a recent meta-analysis it appeared that online post-dilution hemodiafiltration (HDF), especially with a high convection volume (HV-HDF), is associated with superior overall and cardiovascular survival, if compared to standard hemodialysis (HD). The mechanism(s) behind this effect, however, is (are) still unclear. In this respect, a lower incidence of intradialytic hypotension (IDH), and hence less tissue injury, may play a role. To address these items, the HOLLANT study was designed.

METHODS

HOLLANT is a Dutch multicentre randomized controlled cross-over trial. In total, 40 prevalent dialysis patients will be included and, after a run-in phase, exposed to standard HD, HD with cooled dialysate, low-volume HDF and high-volume HDF (Dialog iQ® machine) in a randomized fashion. The primary endpoint is an intradialytic nadir in systolic blood pressure (SBP) of < 90 and < 100 mmHg for patients with predialysis SBP < 159 and ≥ 160 mmHg, respectively. The main secondary outcomes are 1) intradialytic left ventricle (LV) chamber quantification and deformation, 2) intradialytic hemodynamic profile of SBP, diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure (PP), 3) organ and tissue damage, such as the release of specific cellular components, and 4) patient reported symptoms and thermal perceptions during each modality.

DISCUSSION

The current trial is primarily designed to test the hypothesis that a lower incidence of intradialytic hypotension contributes to the superior survival of (HV)-HDF. A secondary objective of this investigation is the question whether changes in the intradialytic blood pressure profile correlate with organ dysfunction and tissue damage, and/or patient discomfort.

TRIAL REGISTRATION

Registered Report Identifier: NCT03249532 # ( ClinicalTrials.gov ). Date of registration: 2017/08/15.

The probability of receiving a kidney transplantation in end-stage kidney disease patients who are treated with haemodiafiltration or haemodialysis: a pooled individual participant data from four randomised controlled trials

Background

Due to a critical shortage of available kidney grafts, most patients with Stage 5 Chronic Kidney Disease (CKD5) require bridging dialysis support. It remains unclear whether treatment by different dialysis modalities changes the selection and/or preparation of a potential transplant candidate. Therefore, we assessed whether the likelihood of receiving kidney transplant (both living or deceased kidney donors) differs between haemodialysis (HD) and online haemodiafiltration (HDF) in patients with CKD5D.

Methods

Individual participant data from four randomised controlled trials comparing online HDF with HD were used. Information on kidney transplant was obtained during follow-up. The likelihood of receiving a kidney transplant was compared between HD and HDF, and evaluated across different subgroups: age, sex, diabetes, history of cardiovascular disease, albumin, dialysis vintage, fistula, and level of convection volume standardized to body surface area. Hazard ratios (HRs), with corresponding 95% confidence intervals (95% CI), comparing the effect of online HDF versus HD on the likelihood of receiving a kidney transplant, were estimated using Cox proportional hazards models with a random effect for study.

Results

After a median follow-up of 2.5 years (Q1 to Q3: 1.9–3.0), 331 of the 1620 (20.4%) patients with CKD5D received a kidney transplant. This concerned 22% (n = 179) of patients who were treated with online HDF compared with 19% (n = 152) of patients who were treated with HD. No differences in the likelihood of undergoing a kidney transplant were found between the two dialysis modalities in both the crude analyse (HR: 1.07, 95% CI: 0.86–1.33) and adjusted analysis for age, sex, diabetes, cardiovascular history, albumin, and creatinine (HR: 1.15, 95%-CI: 0.92–1.44). There was no evidence for a differential effect across subgroups based on patient- and disease-characteristics nor in different categories of convection volumes.

Conclusions

Treatment with HD and HDF does not affect the selection and/or preparation of CKD5D patients for kidney transplant given that the likelihood of receiving a kidney transplant does not differ between the dialysis modalities. These finding persisted across a variety of subgroups differing in patient and disease characteristics and is not affected by the level of convection volume delivered during HDF treatment sessions.

Carotid Intima-Media Thickness Progression as Surrogate Marker for Cardiovascular Risk: Meta-Analysis of 119 Clinical Trials Involving 100 667 Patients

BACKGROUND

To quantify the association between effects of interventions on carotid intima-media thickness (cIMT) progression and their effects on cardiovascular disease (CVD) risk.

METHODS

We systematically collated data from randomized, controlled trials. cIMT was assessed as the mean value at the common-carotid-artery; if unavailable, the maximum value at the common-carotid-artery or other cIMT measures were used. The primary outcome was a combined CVD end point defined as myocardial infarction, stroke, revascularization procedures, or fatal CVD. We estimated intervention effects on cIMT progression and incident CVD for each trial, before relating the 2 using a Bayesian meta-regression approach.

RESULTS

We analyzed data of 119 randomized, controlled trials involving 100 667 patients (mean age 62 years, 42% female). Over an average follow-up of 3.7 years, 12 038 patients developed the combined CVD end point. Across all interventions, each 10 μm/y reduction of cIMT progression resulted in a relative risk for CVD of 0.91 (95% Credible Interval, 0.87-0.94), with an additional relative risk for CVD of 0.92 (0.87-0.97) being achieved independent of cIMT progression. Taken together, we estimated that interventions reducing cIMT progression by 10, 20, 30, or 40 μm/y would yield relative risks of 0.84 (0.75-0.93), 0.76 (0.67-0.85), 0.69 (0.59-0.79), or 0.63 (0.52-0.74), respectively. Results were similar when grouping trials by type of intervention, time of conduct, time to ultrasound follow-up, availability of individual-participant data, primary versus secondary prevention trials, type of cIMT measurement, and proportion of female patients.

CONCLUSIONS

The extent of intervention effects on cIMT progression predicted the degree of CVD risk reduction. This provides a missing link supporting the usefulness of cIMT progression as a surrogate marker for CVD risk in clinical trials.

Change in FGF23 concentration over time and its association with all-cause mortality in patients treated with haemodialysis or haemodiafiltration

Background

Previous studies in patients on haemodialysis (HD) have shown an association of fibroblast growth factor 23 (FGF23) with all-cause mortality. As of yet, the result of FGF23 lowering on mortality is unknown in this population.

Methods

FGF23 was measured in a subset of 404 patients from the Dutch CONvective TRansport STudy (CONTRAST study) [a randomized trial in prevalent dialysis patients comparing HD and haemodiafiltration (HDF) with clinical outcome] at baseline and Months 6 and 12. A substantial decline of FGF23 change over time was anticipated in patients randomized to HDF since HDF induces higher dialytic clearance of FGF23. The associations of both baseline FGF23 and 6-months change in FGF23 with all-cause mortality were analysed. In addition, the difference in FGF23 change between HD and HDF was explored. Furthermore, the role of dialysis modality in the association between FGF23 change and outcome was analysed.

Results

No association was observed between quartiles of baseline FGF23 and all-cause mortality. Over 6 months, FGF23 declined in patients on HDF, whereas FGF23 remained stable in patients on HD. A decrease in FGF23 was not associated with improved survival compared with a stable FGF23 concentration. However, increasing FGF23 was associated with a significantly higher mortality risk, both in crude and fully adjusted models [hazard ratio 2.01 (95% confidence interval 1.30–3.09)].

Conclusion

Whereas no association between a single value of FGF23 and all-cause mortality was found, increasing FGF23 concentrations did identify patients at risk for mortality. Since lowering FGF23 did not improve outcome, this study found no argument for therapeutically lowering FGF23.

Long-Term Peridialytic Blood Pressure Patterns in Patients Treated by Hemodialysis and Hemodiafiltration

Introduction

Online postdilution hemodiafiltration (HDF) is associated with a lower all-cause and cardiovascular mortality than hemodialysis (HD). This may depend on a superior peridialytic (pre- and postdialysis, and the difference between these 2 parameters) hemodynamic profile.

Methods

In this retrospective cohort analysis of individual participant data (IPD) from 3 randomized controlled trials (RCTs) (n = 2011), the effect of HDF and HD on 2-year peridialytic blood pressure (BP) patterns was assessed. Long-term peridialytic systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and pulse pressure (PP), as well as the deltas (post- minus predialytic) were assessed in the total group of patients. Thereafter, these variables were compared between patients on HD and HDF, and in the latter group between quartiles of convection volume.

Results

Mean pre- and postdialysis SBP, DBP, and MAP declined significantly during follow-up (predialytic: SBP −2.16 mm Hg, DBP −2.88 mm Hg, MAP −2.64 mm Hg), PP increased (predialytic 0.96 mm Hg). Peridialytic deltas remained unaltered. Differences between the 2 modalities, or between quartiles of convection volume were not observed. BP changes were independent of various baseline characteristics, including the decline in body weight over time.

Conclusion

We speculate that the combination of a decreasing SBP and an increasing PP may be the clinical sequelae of a worsening cardiovascular system. Because especially HDF with a high convection volume has been associated with a beneficial effect on survival, our study does not support the view that superior peridialytic BP control contributes to this effect.

The effect of natriuretic C-type peptide and its change over time on mortality in patients on haemodialysis or haemodiafiltration

Background

C-type natriuretic peptide (CNP) and its co-product N-terminal proCNP (NTproCNP) have been associated with beneficial effects on the cardiovascular system. In prevalent dialysis patients, however, a relation between NTproCNP and mortality has not yet been investigated. Furthermore, as a middle molecular weight substance, its concentration might be influenced by dialysis modality.

Methods

In a cohort of patients treated with haemodialysis (HD) or haemodiafiltration (HDF), levels of NTproCNP were measured at baseline and 6, 12, 24 and 36 months. The relation between serum NTproCNP and mortality and the relation between the 6-month rate of change of NTproCNP and mortality were analysed using Cox regression models. For the longitudinal analyses, linear mixed models were used.

Results

In total, 406 subjects were studied. The median baseline serum NTproCNP was 93 pmol/L and the median follow-up was 2.97 years. No relation between baseline NTproCNP or its rate of change over 6 months and mortality was found. NTproCNP levels remained stable in HD patients, whereas NTproCNP decreased significantly in HDF patients. The relative decline depended on the magnitude of the convection volume.

Conclusions

In our study, levels of NTproCNP appear strongly elevated in prevalent dialysis patients. Second, while NTproCNP remains unaltered in HD patients, its levels decline in individuals treated with HDF, with the decline dependent on the magnitude of the convection volume. Third, NTproCNP is not related to mortality in this population. Thus NTproCNP does not seem to be a useful marker for mortality risk in dialysis patients.

Serum sclerostin: relation with mortality and impact of hemodiafiltration

Background

The glycoprotein sclerostin (Scl; 22 kDa), which is involved in bone metabolism, may play a role in vascular calcification in haemodialysis (HD) patients. In the present study, we investigated the relation between serum Scl (sScl) and mortality. The effects of dialysis modality and the magnitude of the convection volume in haemodiafiltration (HDF) on sScl were also investigated.

Methods

In a subset of patients from the CONTRAST study, a randomized controlled trial comparing HDF with HD, sScl was measured at baseline and at intervals of 6, 12, 24 and 36 months. Patients were divided into quartiles, according to their baseline sScl. The relation between time-varying sScl and mortality with a 4-year follow-up period was investigated using crude and adjusted Cox regression models. Linear mixed models were used for longitudinal measurements of sScl.

Results

The mean (±standard deviation) age of 396 test subjects was 63.6 (±13.9 years), 61.6% were male and the median follow-up was 2.9 years. Subjects with the highest sScl had a lower mortality risk than those with the lowest concentrations [adjusted hazard ratio 0.51 (95% confidence interval, CI, 0.31-0.86, P = 0.01)]. Stratified models showed a stable sScl in patients treated with HD (Δ +2.9 pmol/L/year, 95% CI -0.5 to +6.3, P = 0.09) and a decreasing concentration in those treated with HDF (Δ -4.5 pmol/L/year, 95% CI -8.0 to -0.9, P = 0.02). The relative change in the latter group was related to the magnitude of the convection volume.

Conclusions

(i) A high sScl is associated with a lower mortality risk in patients with end-stage kidney disease; (ii) treatment with HDF causes sScl to fall; and (iii) the relative decline in patients treated with HDF is dependent on the magnitude of the convection volume.

Long-term clinical parameters after switching to nocturnal haemodialysis: a Dutch propensity-score-matched cohort study comparing patients on nocturnal haemodialysis with patients on three-times-a-week haemodialysis/haemodiafiltration

OBJECTIVES

Nocturnal haemodialysis (NHD), characterised by 8-hour sessions ≥3 times a week, is known to improve clinical parameters in the short term compared with conventional-schedule haemodialysis (HD), generally 3×3.5-4 hours a week. We studied long-term effects of NHD and used patients on conventional HD/haemodiafiltration (HDF) as controls.

DESIGN

Four-year prospective follow-up of patients who switched to NHD; we compared patients with patients on HD/HDF using propensity score matching.

SETTING

28 Dutch dialysis centres.

PARTICIPANTS

We included 159 patients starting with NHD any time since 2004, aged 56.7±12.9 years, with median dialysis vintage 2.3 (0.9-5.1) years. We propensity-score matched 100 patients on NHD to 100 on HD/HDF.

PRIMARY AND SECONDARY OUTCOME MEASURES

Control of hypertension (predialysis blood pressure, number of antihypertensives), phosphate (phosphate, number of phosphate binders), nutritional status and inflammation (albumin, C reactive protein and postdialysis weight) and anaemia (erythropoiesis-stimulating agent (ESA) resistance).

RESULTS

Switching to NHD was associated with a non-significant reduction of antihypertensives compared with HD/HDF (OR <2 types 2.17, 95% CI 0.86 to 5.50, P=0.11); and a prolonged lower need for phosphate binders (OR <2 types 1.83, 95% CI 1.10 to 3.03, P=0.02). NHD was not associated with significant changes in blood pressure or phosphate. NHD was associated with significantly higher albumin over time compared with HD/HDF (0.70 g/L/year, 95% CI 0.10 to 1.30, P=0.02). ESA resistance decreased significantly in NHD compared with HD/HDF, resulting in a 33% lower ESA dose in the long term.

CONCLUSIONS

After switching to NHD, the lower need for antihypertensives, phosphate binders and ESA persists for at least 4 years. These sustained improvements in NHD contrast significantly with the course of these parameters during continued treatment with conventional-schedule HD and HDF. NHD provides an optimal form of dialysis, also suitable for patients expected to have a long waiting time for transplantation or those convicted to indefinite dialysis.

The importance of considering competing treatment affecting prognosis in the evaluation of therapy in trials: the example of renal transplantation in hemodialysis trials

Background

During the follow-up in a randomized controlled trial (RCT), participants may receive additional (non-randomly allocated) treatment that affects the outcome. Typically such additional treatment is not taken into account in evaluation of the results. Two pivotal trials of the effects of hemodiafiltration (HDF) versus hemodialysis (HD) on mortality in patients with end-stage renal disease reported differing results. We set out to evaluate to what extent methods to take other treatments (i.e. renal transplantation) into account may explain the difference in findings between RCTs. This is illustrated using a clinical example of two RCTs estimating the effect of HDF versus HD on mortality.

Methods

Using individual patient data from the Estudio de Supervivencia de Hemodiafiltración On-Line (ESHOL; n  =  902) and The Dutch CONvective TRAnsport STudy (CONTRAST; n  = 714) trials, five methods for estimating the effect of HDF versus HD on all-cause mortality were compared: intention-to-treat (ITT) analysis (i.e. not taking renal transplantation into account), per protocol exclusion (PP excl ; exclusion of patients who receive transplantation), PP cens (censoring patients at the time of transplantation), transplantation-adjusted (TA) analysis and an extension of the TA analysis (TA ext ) with additional adjustment for variables related to both the risk of receiving a transplant and the risk of an outcome (transplantation-outcome confounders). Cox proportional hazards models were applied.

Results

Unadjusted ITT analysis of all-cause mortality led to differing results between CONTRAST and ESHOL: hazard ratio (HR) 0.95 (95% CI 0.75-1.20) and HR 0.76 (95% CI 0.59-0.97), respectively; difference between 5 and 24% risk reductions. Similar differences between the two trials were observed for the other unadjusted analytical methods (PP cens, PP excl , TA) The HRs of HDF versus HD treatment became more similar after adding transplantation as a time-varying covariate and including transplantation-outcome confounders: HR 0.89 (95% CI 0.69-1.13) in CONTRAST and HR 0.80 (95% CI 0.62-1.02) in ESHOL.

Conclusions

The apparent differences in estimated treatment effects between two dialysis trials were to a large extent attributable to differences in applied methodology for taking renal transplantation into account in their final analyses. Our results exemplify the necessity of careful consideration of the treatment effect of interest when estimating the therapeutic effect in RCTs in which participants may receive additional treatments.

Mortality reduction by post-dilution online-haemodiafiltration: a cause-specific analysis

Background

From an individual participant data (IPD) meta-analysis from four randomized controlled trials comparing haemodialysis (HD) with post-dilution online-haemodiafiltration (ol-HDF), previously it appeared that HDF decreases all-cause mortality by 14% (95% confidence interval 25; 1) and fatal cardiovascular disease (CVD) by 23% (39; 3). Significant differences were not found for fatal infections and sudden death. So far, it is unclear, however, whether the reduced mortality risk of HDF is only due to a decrease in CVD events and if so, which CVD in particular is prevented, if compared with HD.

Methods

The IPD base was used for the present study. Hazard ratios and 95% confidence intervals for cause-specific mortality overall and in thirds of the convection volume were calculated using the Cox proportional hazard regression models. Annualized mortality and numbers needed to treat (NNT) were calculated as well.

Results

Besides 554 patients dying from CVD, fatal infections and sudden death, 215 participants died from 'other causes', such as withdrawal from treatment and malignancies. In this group, the mortality risk was comparable between HD and ol-HDF patients, both overall and in thirds of the convection volume. Subdivision of CVD mortality in fatal cardiac, non-cardiac and unclassified CVD showed that ol-HDF was only associated with a lower risk of cardiac casualties [0.64 (0.61; 0.90)]. Annual mortality rates also suggest that the reduction in CVD death is mainly due to a decrease in cardiac fatalities, including both ischaemic heart disease and congestion. Overall, 32 and 75 patients, respectively, need to be treated by high-volume HDF (HV-HDF) to prevent one all-cause and one CVD death, respectively, per year.

Conclusion

The beneficial effect of ol-HDF on all-cause and CVD mortality appears to be mainly due to a reduction in fatal cardiac events, including ischaemic heart disease as well as congestion. In HV-HDF, the NNT to prevent one CVD death is 75 per year.

Quality of life as indicator of poor outcome in hemodialysis: relation with mortality in different age groups

BACKGROUND

Physical, cognitive and psychosocial functioning are frequently impaired in dialysis patients and impairment in these domains relates to poor outcome. The aim of this analysis was to compare the prevalence of impairment as measured by the Kidney Disease Quality of Life- Short Form (KDQOL-SF) subscales between the different age categories and to assess whether the association of these subscales with mortality differs between younger and older dialysis patients.

METHODS

This study included data from 714 prevalent hemodialysis patients, from 26 centres, who were enrolled in the CONvective TRAnsport STudy (CONTRAST NCT00205556, 09-12-2005). Baseline HRQOL domains were evaluated for patients <65 years, 65-74 years and over 75 years. Multivariable Cox proportional hazards analyses were performed to assess the relation between the separate domains and 2-year mortality.

RESULTS

Emotional health was higher in patients over the age of 75 compared to younger patients (mean level 71, 73 and 77 for increasing age categories respectively, p = 0.02), whilst physical functioning was significantly lower in older patients (mean level 60, 48 and 40, p < 0.01). A low level of physical functioning (Hazard Ratio (HR) 1.72 [95%Confidence Interval (CI) 1.02-2.73]), emotional health (HR 1.85 [95% 1.30-2.63]), and social functioning (HR 1.59 [95% CI 1.12-2.26]), was individually associated with an increased 2-year mortality within the whole population. The absence of effect modification suggests no evidence for different relations within the older age groups.

CONCLUSIONS

In dialysis patients, older age is associated with lower levels of physical functioning, whilst the level of emotional health is not associated with age. KDQOL-SF domains physical functioning, emotional health and social functioning are independently associated with mortality in prevalent younger and older hemodialysis patients.

A closer look at the trajectory of physical functioning in chronic hemodialysis

Background

in chronic hemodialysis, physical functioning (PF) is known to be poor. We set out to assess to what extent chronic dialysis patients are able to maintain a good physical condition over time and what the influence of age is on the trajectory of PF.

Methods

we used data form 714 prevalent hemodialysis patients, enrolled in the CONvective TRAnsport STudy (CONTRAST). The PF subscale of the KDQOL SF-36 was assessed at baseline (n = 679) and during 2 years of follow-up (n = 298). Baseline PF score (0-100) was categorized into tertiles (good, intermediate and low). Change of PF of ≥ 5 points was considered clinically relevant. A regression model was applied to assess factors related to 'decline of PF (≥5 points)/low PF (0-33) at follow-up'.

Results

during follow-up, only 15.3 % (1 out of 6) of patients succeeded in maintaining a good physical condition, the remainder deteriorated or died. Of the older patients (≥75) only 3.6% remained in a good physical condition. Factors related to decline/low PF were increasing age (odds ratio [OR] = 1.96 [95% CI: 1.03-3.72] for 65-74 years and OR = 2.38 [95%CI: 1.17-4.84] for ≥75 years compared to <65 years) and albumin (OR = 1.10 [95%CI: 1.01-1.18] per g/L decrease).

Conclusion

very few hemodialysis patients maintain a good physical condition over a 2-year time span. Especially in older patients, physical performance is poor and decline is faster than in the healthy population. These findings should be taken into account when considering dialysis in older patients and more emphasis should be placed to attempts for improving physical condition.

Achieving high convection volumes in postdilution online hemodiafiltration: a prospective multicenter study

Background. Available evidence suggests a reduced mortality risk for patients treated with high-volume postdilution hemodiafiltration (HDF) when compared with hemodialysis (HD) patients. As the magnitude of the convection volume depends on treatment-related factors rather than patient-related characteristics, we prospectively investigated whether a high convection volume (defined as ≥22 L/session) is feasible in the majority of patients (>75%).

Methods. A multicenter study was performed in adult prevalent dialysis patients. Nonparticipating eligible patients formed the control group. Using a stepwise protocol, treatment time (up to 4 hours), blood flow rate (up to 400 mL/min) and filtration fraction (up to 33%) were optimized as much as possible. The convection volume was determined at the end of this optimization phase and at 4 and 8 weeks thereafter.

Results. Baseline characteristics were comparable in participants (n = 86) and controls (n = 58). At the end of the optimization and 8 weeks thereafter, 71/86 (83%) and 66/83 (80%) of the patients achieved high-volume HDF (mean 25.5 ± 3.6 and 26.0 ± 3.4 L/session, respectively). While treatment time remained unaltered, mean blood flow rate increased by 27% and filtration fraction increased by 23%. Patients with <22 L/session had a higher percentage of central venous catheters (CVCs), a shorter treatment time and lower blood flow rate when compared with patients with ≥22 L/session.

Conclusions. High-volume HDF is feasible in a clear majority of dialysis patients. Since none of the patients agreed to increase treatment time, these findings indicate that high-volume HDF is feasible just by increasing blood flow rate and filtration fraction.

Cost-Effectiveness Analysis of High-Efficiency Hemodiafiltration Versus Low-Flux Hemodialysis Based on the Canadian Arm of the CONTRAST Study

AIM

The aim of this study was to assess the cost effectiveness of high-efficiency on-line hemodiafiltration (OL-HDF) compared with low-flux hemodialysis (LF-HD) for patients with end-stage renal disease (ESRD) based on the Canadian (Centre Hospitalier de l'Université de Montréal) arm of a parallel-group randomized controlled trial (RCT), the CONvective TRAnsport STudy.

METHODS

An economic evaluation was conducted for the period of the RCT (74 months). In addition, a Markov state transition model was constructed to simulate costs and health benefits over lifetime. The primary outcome was costs per quality-adjusted life-year (QALY) gained. The analysis had the perspective of the Quebec public healthcare system.

RESULTS

A total of 130 patients were randomly allocated to OL-HDF (n = 67) and LF-HD (n = 63). The cost-utility ratio of OL-HDF versus LF-HD was Can$53,270 per QALY gained over lifetime. This ratio was fairly robust in the sensitivity analysis. The cost-utility ratio was lower than that of LF-HD compared with no treatment (immediate death), which was Can$93,008 per QALY gained.

CONCLUSIONS

High-efficiency OL-HDF can be considered a cost-effective treatment for ESRD in a Canadian setting. Further research is needed to assess cost effectiveness in other settings and healthcare systems.

Serum Magnesium and Sudden Death in European Hemodialysis Patients

Despite suggestions that higher serum magnesium (Mg) levels are associated with improved outcome, the association with mortality in European hemodialysis (HD) patients has only scarcely been investigated. Furthermore, data on the association between serum Mg and sudden death in this patient group is limited. Therefore, we evaluated Mg in a post-hoc analysis using pooled data from the CONvective TRAnsport STudy (CONTRAST, NCT00205556), a randomized controlled trial (RCT) evaluating the survival risk in dialysis patients on hemodiafiltration (HDF) compared to HD with a mean follow-up of 3.1 years. Serum Mg was measured at baseline and 6, 12, 24 and 36 months thereafter. Cox proportional hazards models, adjusted for confounders using inverse probability weighting, were used to estimate hazard ratios (HRs) of baseline serum Mg on all-cause mortality, cardiovascular mortality, non-cardiovascular mortality and sudden death. A generalized linear mixed model was used to investigate Mg levels over time. Out of 714 randomized patients, a representative subset of 365 (51%) were analyzed in the present study. For every increase in baseline serum Mg of 0.1 mmol/L, the HR for all-cause mortality was 0.85 (95% CI 0.77–94), the HR for cardiovascular mortality 0.73 (95% CI 0.62–0.85) and for sudden death 0.76 (95% CI 0.62–0.93). These findings did not alter after extensive correction for potential confounders, including treatment modality. Importantly, no interaction was found between serum phosphate and serum Mg. Baseline serum Mg was not related to non-cardiovascular mortality. Mg decreased slightly but statistically significant over time (Δ -0.011 mmol/L/year, 95% CI -0.017 to -0.009, p = 0.03). In short, serum Mg has a strong, independent association with all-cause mortality, cardiovascular mortality and sudden death in European HD patients. Serum Mg levels decrease slightly over time.

Comparing Tests Assessing Protein-Energy Wasting: Relation With Quality of Life

OBJECTIVE

Protein-energy wasting (PEW), a state of decreased bodily protein and energy fuels, is highly prevalent among hemodialysis patients. The best method to determine PEW, however, remains debated. As an independent, negative association between PEW and quality of life (QOL) has been demonstrated, establishing which nutrition-related test correlates best with QOL may help to identify how PEW should preferably be assessed.

DESIGN AND METHODS

Data were used from CONTRAST, a cohort of end-stage kidney disease patients. At baseline, Subjective Global Assessment (SGA), Malnutrition Inflammation Score (MIS), Geriatric Nutritional Risk Index, composite score on protein-energy nutritional status, normalized protein nitrogen appearance, body mass index, serum albumin, and serum creatinine were determined. QOL was assessed by the Kidney Disease Quality of Life Short Form 1.3. The present study reports on 2 general and 11 kidney disease-specific QOL scores. Spearman's rho (ρ) was calculated to determine correlations between nutrition-related tests and QOL domains. Twelve months after randomization, a sensitivity analysis was performed to test the robustness of the results.

RESULTS

Of 714 patients, 489 representative subjects were available for analysis. All tests correlated with the Physical Component Score, except body mass index. Only SGA and MIS correlated significantly with the Mental Component Score. SGA correlated significantly with 10 of 11 kidney disease-specific QOL domains. The MIS not only correlated significantly with all (11) kidney disease-specific QOL domains but also with higher correlation coefficients.

CONCLUSION

Of the 8 investigated nutrition-related tests, only MIS correlates with all QOL domains (13 of 13) with the strongest associations.

Haemodiafiltration and mortality in end-stage kidney disease patients: a pooled individual participant data analysis from four randomized controlled trials

BACKGROUND

Mortality rates remain high for haemodialysis (HD) patients and simply increasing the HD dose to remove more small solutes does not improve survival. Online haemodiafiltration (HDF) provides additional clearance of larger toxins compared with standard HD. Randomized controlled trials (RCTs) comparing HDF with conventional HD on all-cause and cause-specific mortality in end-stage kidney disease (ESKD) patients reported inconsistent results and were at high risk of bias. We conducted a pooled individual participant data analysis of RCTs to provide the most reliable evidence to date on the effects of HDF on mortality outcomes in ESKD patients.

METHODS

Individual participant data were used from four trials that compared online HDF with HD and were designed to examine the effects of HDF on mortality endpoints. Bias by informative censoring of patients was resolved. Hazard ratios (HRs) and 95% confidence intervals (95% CI) comparing the effect of online HDF versus HD on all-cause and cause-specific mortality were calculated using the Cox proportional hazard regression models. The relationship between convection volume and the study outcomes was examined by delivered convection volume standardized to body surface area.

RESULTS

After a median follow-up of 2.5 years (Q1-Q3: 1.9-3.0), 769 of the 2793 participants had died (292 cardiovascular deaths). Online HDF reduced the risk of all-cause mortality by 14% (95% CI: 1%; 25%) and cardiovascular mortality by 23% (95% CI: 3%; 39%). There was no evidence for a differential effect in subgroups. The largest survival benefit was for patients receiving the highest delivered convection volume [>23 L per 1.73 m(2) body surface area (BSA) per session], with a multivariable-adjusted HR of 0.78 (95% CI: 0.62; 0.98) for all-cause mortality and 0.69 (95% CI: 0.47; 1.00) for cardiovascular disease mortality.

CONCLUSIONS

This pooled individual participant analysis on the effects of online HDF compared with conventional HD indicates that online HDF reduces the risk of mortality in ESKD patients. This effect holds across a variety of important clinical subgroups of patients and is most pronounced for those receiving a higher convection volume normalized to BSA.

Eccentric Left Ventricular Hypertrophy and Sudden Death in Patients with End-Stage Kidney Disease

BACKGROUND/AIMS

Both all-cause and cardiovascular mortality risks are extremely high in patients with end-stage kidney disease (ESKD). Sudden death accounts for approximately one-quarter of all fatal events. Left ventricular hypertrophy (LVH) is a known risk factor for mortality and can be divided in 2 types: concentric and eccentric. This study evaluated possible differences in all-cause mortality, cardiovascular mortality and sudden death between prevalent ESKD patients with concentric and eccentric LVH.

METHODS

Participants of the CONvective TRAnsport STudy (CONTRAST) who underwent transthoracic echocardiography (TTE) at baseline were analyzed. In patients with LVH, a relative wall thickness of ≤0.42 was considered eccentric and >0.42 was considered concentric hypertrophy. Cox proportional hazards models, adjusted for potential confounders, were used to calculate hazard ratios (HRs) of patients with eccentric LVH versus patients with concentric LVH for all-cause mortality, cardiovascular mortality and sudden death.

RESULTS

TTE was performed in 328 CONTRAST participants. LVH was present in 233 participants (71%), of which 87 (37%) had concentric LVH and 146 (63%) eccentric LVH. The HR for all-cause mortality of eccentric versus concentric LVH was 1.14 (p = 0.52), 1.79 (p = 0.12) for cardiovascular mortality and 4.23 (p = 0.02) for sudden death in crude analyses. Propensity score-corrected HR for sudden death in patients with eccentric LVH versus those with concentric LVH was 5.22 (p = 0.03).

CONCLUSIONS

(1) The hazard for all-cause mortality, cardiovascular mortality and sudden death is markedly increased in patients with LVH. (2) The sudden death risk is significantly higher in ESKD patients with eccentric LVH compared to subjects with concentric LVH.

The Effect of Online Hemodiafiltration on Infections: Results from the CONvective TRAnsport STudy

BACKGROUND

Hemodialysis (HD) patients have a high risk of infections. The uremic milieu has a negative impact on several immune responses. Online hemodiafiltration (HDF) may reduce the risk of infections by ameliorating the uremic milieu through enhanced clearance of middle molecules. Since there are few data on infectious outcomes in HDF, we compared the effects of HDF with low-flux HD on the incidence and type of infections.

PATIENTS AND METHODS

We used data of the 714 HD patients (age 64 ±14, 62% men, 25% Diabetes Mellitus, 7% catheters) participating in the CONvective TRAnsport STudy (CONTRAST), a randomized controlled trial evaluating the effect of HDF as compared to low-flux HD. The events were adjudicated by an independent event committee. The risk of infectious events was compared with Cox regression for repeated events and Cox proportional hazard models. The distributions of types of infection were compared between the groups.

RESULTS

Thirty one percent of the patients suffered from one or more infections leading to hospitalization during the study (median follow-up 1.96 years). The risk for infections during the entire follow-up did not differ significantly between treatment arms (HDF 198 and HD 169 infections in 800 and 798 person-years respectively, hazard ratio HDF vs. HD 1.09 (0.88-1.34), P = 0.42. No difference was found in the occurrence of the first infectious event (either fatal, non-fatal or type specific). Of all infections, respiratory infections (25% in HDF, 28% in HD) were most common, followed by skin/musculoskeletal infections (21% in HDF, 13% in HD).

CONCLUSIONS

HDF as compared to HD did not result in a reduced risk of infections, larger studies are needed to confirm our findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00205556.

Treatment Time or Convection Volume in HDF: What Drives the Reduced Mortality Risk?

BACKGROUND/AIMS

Treatment time is associated with survival in hemodialysis (HD) patients and with convection volume in hemodiafiltration (HDF) patients. High-volume HDF is associated with improved survival. Therefore, we investigated whether this survival benefit is explained by treatment time.

METHODS

Participants were subdivided into four groups: HD and tertiles of convection volume in HDF. Three Cox regression models were fitted to calculate hazard ratios (HRs) for mortality of HDF subgroups versus HD: (1) crude, (2) adjusted for confounders, (3) model 2 plus mean treatment time. As the only difference between the latter models is treatment time, any change in HRs is due to this variable.

RESULTS

114/700 analyzed individuals were treated with high-volume HDF. HRs of high-volume HDF are 0.61, 0.62 and 0.64 in the three models, respectively (p values <0.05). Confidence intervals of models 2 and 3 overlap.

CONCLUSION

The survival benefit of high-volume HDF over HD is independent of treatment time.

High convection volume in online post-dilution haemodiafiltration: relevance, safety and costs

Increasing evidence suggests that treatment with online post-dilution haemodiafiltration (HDF) improves clinical outcome in patients with end-stage kidney disease, if compared with haemodialysis (HD). Although the primary analyses of three large randomized controlled trials (RCTs) showed inconclusive results, post hoc analyses of these and previous observational studies comparing online post-dilution HDF with HD showed that the risk of overall and cardiovascular mortality is lowest in patients who are treated with high-volume HDF. As such, the magnitude of the convection volume seems crucial and can be considered as the ‘dose’ of HDF. In this narrative review, the relevance of high convection volume in online post-dilution HDF is discussed. In addition, we briefly touch upon some safety and cost issues.

A Comparison of 8 Nutrition-Related Tests to Predict Mortality in Hemodialysis Patients

OBJECTIVE

Protein-energy wasting (PEW) describes a state of decreased protein and energy fuels and is highly prevalent in hemodialysis patients. As PEW is associated with mortality, it should be detected accurately and easily. This study investigated which nutrition-related test predicts mortality and morbidity best in hemodialysis patients.

DESIGN AND SUBJECTS

Data were used from CONTRAST, a cohort of end-stage kidney disease patients. Subjective Global Assessment (SGA), Malnutrition Inflammation Score (MIS), Geriatric Nutritional Risk Index (GNRI), composite score of Protein-Energy Nutritional Status (cPENS), serum albumin, serum creatinine, body mass index, and normalized protein nitrogen appearance rate were assessed at baseline. End points were all-cause mortality, cardiovascular events, and infection. Discriminative value of every test was assessed with Harrell's C statistic and calibration tested using the Hosmer-Lemeshow goodness-of-fit test. Ultimately, in every test, 4 groups were created to compare (1) hazard ratios (HR; worst vs best group), (2) HR increase per group, and (3) HR of worst group versus other groups.

RESULTS

In total, 489 patients were analyzed. Median follow-up was 2.97 years (interquartile range, 1.67-4.47 years). MIS, GNRI, albumin, and creatinine discriminated all-cause mortality equally. SGA, cPENS, body mass index, and normalized protein nitrogen appearance were inferior. cPENS and creatinine were inadequately calibrated. Of the remaining tests, GNRI predicted mortality less when comparing HRs. MIS and albumin predicted mortality equally well. In a subanalysis, these also predicted infection equally well, but MIS predicted cardiovascular events better.

CONCLUSION

Of the 8 investigated nutrition-related tests, MIS and albumin predict mortality best in hemodialysis patients. As one has no added value over the other, we conclude that mortality is most easily predicted in hemodialysis patients by serum albumin.

Hepcidin in chronic kidney disease: not an anaemia management tool, but promising as a cardiovascular biomarker

Hepcidin is a key regulator of iron homeostasis and plays a role in the pathogenesis of anaemia of chronic disease. Its levels are increased in patients with chronic kidney disease (CKD) due to diminished renal clearance and an inflammatory state. Increased hepcidin levels in CKD patients are supposed to be responsible for functional iron deficiency in these patients and contribute to renal anaemia and resistance to erythropoiesis-stimulating agents. Therefore, hepcidin was purported to be useful as a management tool guiding treatment of renal anaemia. Furthermore, since hepcidin is associated with iron accumulation in macrophages in the vessel wall inducing oxidative stress and atherosclerosis, it has been speculated that hepcidin might function as a biomarker of cardiovascular disease. In this descriptive review, the merits of hepcidin with respect to its role in the pathophysiology of renal anaemia in CKD patients, its presumptive role as a practical diagnostic tool guiding management of renal anaemia, and its possible usefulness as a prognostic biomarker will be discussed.

Resistance to erythropoiesis stimulating agents in patients treated with online hemodiafiltration and ultrapure low-flux hemodialysis: results from a randomized controlled trial (CONTRAST)

Resistance to erythropoiesis stimulating agents (ESA) is common in patients undergoing chronic hemodialysis (HD) treatment. ESA responsiveness might be improved by enhanced clearance of uremic toxins of middle molecular weight, as can be obtained by hemodiafiltration (HDF). In this analysis of the randomized controlled CONvective TRAnsport STudy (CONTRAST; NCT00205556), the effect of online HDF on ESA resistance and iron parameters was studied. This was a pre-specified secondary endpoint of the main trial. A 12 months' analysis of 714 patients randomized to either treatment with online post-dilution HDF or continuation of low-flux HD was performed. Both groups were treated with ultrapure dialysis fluids. ESA resistance, measured every three months, was expressed as the ESA index (weight adjusted weekly ESA dose in daily defined doses [DDD]/hematocrit). The mean ESA index during 12 months was not different between patients treated with HDF or HD (mean difference HDF versus HD over time 0.029 DDD/kg/Hct/week [−0.024 to 0.081]; P = 0.29). Mean transferrin saturation ratio and ferritin levels during the study tended to be lower in patients treated with HDF (−2.52% [−4.72 to −0.31]; P = 0.02 and −49 ng/mL [−103 to 4]; P = 0.06 respectively), although there was a trend for those patients to receive slightly more iron supplementation (7.1 mg/week [−0.4 to 14.5]; P = 0.06).

In conclusion, compared to low-flux HD with ultrapure dialysis fluid, treatment with online HDF did not result in a decrease in ESA resistance.

Trial Registration

ClinicalTrials.gov NCT00205556

Clinical predictors of decline in nutritional parameters over time in ESRD

BACKGROUND AND OBJECTIVES

Inflammation and malnutrition are important features in patients with ESRD; however, data on changes in these parameters over time are scarce. This study aimed to gain insight into changes over time in serum albumin, body mass index, high-sensitivity C-reactive protein, and IL-6 in patients with ESRD and aimed to identify clinical risk factors for deterioration of these parameters.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data were analyzed from the Convective Transport Study, a randomized controlled trial conducted from June 2004 to January 2011, in which 714 patients with chronic ESRD were randomized to either online hemodiafiltration or low-flux hemodialysis. Albumin and body mass index were measured up to 6 years and predialysis C-reactive protein and IL-6 were measured up to 3 years in a subset of 405 participants. Rates of change in these parameters over time were estimated across strata of predefined risk factors with linear mixed-effects models.

RESULTS

Albumin and body mass index decreased and C-reactive protein and IL-6 increased over time. For every incremental year of age at baseline, the yearly excess decline in albumin was 0.003 g/dl (-0.004 to -0.002; P<0.001) and the excess decline in body mass index was 0.02 kg/m(2) per year (-0.02 to -0.01; P<0.001). In patients with diabetes mellitus, there was a yearly excess decline of 0.05 g/dl in albumin (-0.09 to -0.02; P=0.002). Compared with women, men had an excess decline of 0.03 g/dl per year in albumin (-0.06 to -0.001; P=0.05) and an excess increase of 11.6% per year in IL-6 (0.63%-23.6%; P=0.04).

CONCLUSIONS

Despite guideline-based care, all inflammatory and nutritional parameters worsened over time. The deterioration of some of these parameters was more pronounced in men, older patients, and patients with diabetes mellitus. Special focus on the nutritional status of at-risk patients by individualizing medical care might improve their prognosis.

A randomized trial of hemodiafiltration and change in cardiovascular parameters

BACKGROUND AND OBJECTIVE

Increased left ventricular mass (LVM), low ventricular ejection fraction (EF), and high pulse-wave velocity (PWV) relate to overall and cardiovascular mortality in patients with ESRD. The aim of this study was to determine the effect of online hemodiafiltration (HDF) versus low-flux hemodialysis (HD) on LVM, EF, and PWV.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Echocardiography was used to assess LVM and EF in 342 patients in the CONvective TRAnsport STudy followed for up to 4 years. PWV was measured in 189 patients for up to 3 years. Effect of HDF versus HD on LVM, EF, and PWV was evaluated using linear mixed models.

RESULTS

Patients had a mean age of 63 years, and 61% were male. At baseline, median LVM was 227 g (interquartile range [IQR], 183-279 g), and median EF was 65% (IQR, 55%-72%). Median PWV was 9.8 m/s (IQR, 7.5-12.0 m/s). There was no significant difference between the HDF and HD treatment groups in rate of change in LVM (HDF: change, -0.9 g/yr [95% confidence interval (95% CI), -8.9 to 7.7 g]; HD: change, 12.5 g/yr [95% CI, -3.0 to 27.5 g]; P for difference=0.13), EF (HDF: change, -0.3%/yr [95% CI, -2.3% to 1.8%]; HD: change, -3.4%/yr [95% CI, -5.9% to -0.9%]; P=0.17), or PWV (HDF: change, -0.0 m/s per year [95% CI, -0.4 to 0.4 m/s); HD: change, 0.0 m/s per year [95% CI, -0.3 to 0.2 m/s]; P=0.89). No differences in rate of change between treatment groups were observed for subgroups of age, sex, residual kidney function, dialysis vintage, history of cardiovascular disease, diabetes, or convection volume.

CONCLUSIONS

Treatment with online HDF did not affect changes in LVM, EF, or PWV over time compared with HD.

The cost-utility of haemodiafiltration versus haemodialysis in the Convective Transport Study

BACKGROUND

Despite the growing interest in haemodiafiltration (HDF), there is no information on the costs and cost-utility of this dialysis modality yet. It was therefore our objective to study the cost-utility of HDF versus haemodialysis (HD).

METHODS

A cost-utility analysis was performed using a Markov model. It included data from the Convective Transport Study (CONTRAST), a randomized controlled trial that compared online HDF with low-flux HD. Costs were estimated using a societal perspective. Probabilistic sensitivity analyses were performed to study uncertainty.

RESULTS

Total annual costs for HDF and HD were €88 622±19,272 and €86,086±15,945, respectively (in 2009 euros). When modelled over a 5-year period, the incremental cost per quality-adjusted life year (QALY) of HDF versus HD was €287,679. Sensitivity analyses revealed that this amount will not fall below €140,000, even under the most favourable assumptions like a high-convection volume (>20.3 L).

CONCLUSIONS

Based on accepted societal willingness-to-pay thresholds, HDF cannot be considered a cost-effective treatment for patients with end-stage renal disease at present. Apparently, minor additional costs of HDF are not counterbalanced by a relevant QALY gain.

Should we still focus that much on cardiovascular mortality in end stage renal disease patients? The CONvective TRAnsport STudy

Background

We studied the distribution of causes of death in the CONTRAST cohort and compared the proportion of cardiovascular deaths with other populations to answer the question whether cardiovascular mortality is still the principal cause of death in end stage renal disease. In addition, we compared patients who died from the three most common death causes. Finally, we aimed to study factors related to dialysis withdrawal.

Methods

We used data from CONTRAST, a randomized controlled trial in 714 chronic hemodialysis patients comparing the effects of online hemodiafiltration versus low-flux hemodialysis. Causes of death were adjudicated. The distribution of causes of death was compared to that of the Dutch dialysis registry and of the Dutch general population.

Results

In CONTRAST, 231 patients died on treatment. 32% died from cardiovascular disease, 22% due to infection and 23% because of dialysis withdrawal. These proportions were similar to those in the Dutch dialysis registry and the proportional cardiovascular mortality was similar to that of the Dutch general population. cardiovascular death was more common in patients <60 years. Patients who withdrew were older, had more co-morbidity and a lower mental quality of life at baseline. Patients who withdrew had much co-morbidity. 46% died within 5 days after the last dialysis session.

Conclusions

Although the absolute risk of death is much higher, the proportion of cardiovascular deaths in a prevalent end stage renal disease population is similar to that of the general population. In older hemodialysis patients cardiovascular and non-cardiovascular death risk are equally important. Particularly the registration of dialysis withdrawal deserves attention. These findings may be partly limited to the Dutch population.

Aspects of platelet disturbances in haemodialysis patients

Patients with mild-to-chronic kidney disease (CKD) exhibit a variety of haemostatic disorders, ranging from an increased clotting tendency and reductions in the levels of natural inhibitors of coagulation to defective fibrinolysis. In addition, platelet (PLT) abnormalities are common. In this minireview, we report on aspects of haemodialysis (HD)-induced PLT activation. It is demonstrated that PLTs from HD patients are exhausted due to repeated stimulation of HD treatment and recurrent release of PLT degranulation products. During HD, additional aberrations of the haemostatic process occur. Besides deviations of coagulation and fibrinolysis, PLT activation and a reduction in their granule content have been observed during HD treatment. As HD treatment is carried out three times per week, month after month, chronic HD patients may suffer persistently from coagulation defects and PLT disorders on top of the alterations induced by the uraemic state itself. PLT activation occurs together with thrombin and fibrin generation. However, macro fibrin depositions in clot devices are not demonstrated, microaggregates occur not only in the extracorporeal circuit (ECC) but are also present in the blood circulation. As vascular access thrombosis is a frequent complication in patients with HD treatment, it is believed that hypercoagulability could result from vascular changes combined with PLTs and activation of coagulation factors.

Premature aging of the microcirculation in patients with advanced chronic kidney disease

Background

Increasing age and advanced chronic kidney disease (CKD) are both associated with an attenuated vasodilator response of the skin microcirculation. In the present study, we investigated the effect of aging on microvascular reactivity in patients with advanced CKD.

Methods

Acetylcholine (ACh)-mediated endothelium-dependent vasodilation and sodium nitroprusside (SNP)-mediated endothelium-independent vasodilation were assessed by iontophoresis combined with laser Doppler flowmetry. Microvascular function was compared between 52 patients with advanced CKD (stage 4–5: n = 16; end-stage renal disease: n = 36) and 33 healthy control subjects. As aging has an important effect on microvascular function, both control subjects and CKD patients were divided in subgroups younger and older than 45 years. Linear regression analysis was applied to assess potential associations between microvascular function and various demographic and clinical parameters.

Results

There were three main findings. (1) In young patients with advanced CKD, both ACh- and SNP-mediated vasodilations were impaired if compared to young healthy controls (p = 0.04 and p = 0.056, respectively). (2) In young patients with advanced CKD, microvascular function was similar to old healthy controls and elderly patients with advanced CKD. (3) Whereas age was inversely associated with microvascular function in healthy controls (log ACh-mediated vasodilation R = −0.41; p = 0.02 and log SNP-mediated vasodilation R = −0.38; p = 0.03), no such relation was found in patients with advanced CKD.

Conclusions

Our results are consistent with premature aging of the microvascular vasodilatory capacity in patients with advanced CKD.

Hepcidin-25 is related to cardiovascular events in chronic haemodialysis patients

BACKGROUND

The development of atherosclerosis may be enhanced by iron accumulation in macrophages. Hepcidin-25 is a key regulator of iron homeostasis, which downregulates the cellular iron exporter ferroportin. In haemodialysis (HD) patients, hepcidin-25 levels are increased. Therefore, it is conceivable that hepcidin-25 is associated with all-cause mortality and/or fatal and non-fatal cardiovascular (CV) events in this patient group. The aim of the current analysis was to study the relationship between hepcidin-25 and all-cause mortality and both fatal and non-fatal CV events in chronic HD patients.

METHODS

Data from 405 chronic HD patients included in the CONvective TRAnsport STudy (NCT00205556) were studied (62% men, age 63.7 ± 13.9 years [mean ± SD]). The median (range) follow-up was 3.0 (0.8-6.6) years. Hepcidin-25 was measured with mass spectrometry. The relationship between hepcidin-25 and all-cause mortality or fatal and non-fatal CV events was investigated with multivariate Cox proportional hazard models.

RESULTS

Median (interquartile range) hepcidin-25 level was 13.8 (6.6-22.5) nmol/L. During follow-up, 158 (39%) patients died from any cause and 131 (32%) had a CV event. Hepcidin-25 was associated with all-cause mortality in an unadjusted model [hazard ratio (HR) 1.14 per 10 nmol/L, 95% CI 1.03-1.26; P = 0.01], but not after adjustment for all confounders including high-sensitive C-reactive protein (HR 1.02 per 10 nmol/L, 95% CI 0.87-1.20; P = 0.80). At the same time, hepcidin-25 was significantly related to fatal and non-fatal CV events in a fully adjusted model (HR 1.24 per 10 nmol/L, 95% CI 1.05-1.46, P = 0.01).

CONCLUSION

Hepcidin-25 was associated with fatal and non-fatal CV events, even after adjustment for inflammation. Furthermore, inflammation appears to be a significant confounder in the relation between hepcidin-25 and all-cause mortality. These findings suggest that hepcidin-25 might be a novel determinant of CV disease in chronic HD patients.

Effect of hemodiafiltration on quality of life over time

BACKGROUND AND OBJECTIVES

It is unclear if hemodiafiltration leads to a better quality of life compared with hemodialysis. It was, therefore, the aim of this study to assess the effect of hemodiafiltration on quality of life compared with hemodialysis in patients with ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study analyzed the data of 714 patients with a median follow-up of 2 years from the Convective Transport Study. The patients were enrolled between June of 2004 and December of 2009. The Convective Transport Study is a randomized controlled trial on the effect of online hemodiafiltration versus low-flux hemodialysis on all-cause mortality. Quality of life was assessed with the Kidney Disease Quality of Life-Short Form. This questionnaire provides data for a physical and mental composite score and describes kidney disease-specific quality of life in 12 domains. The domains have scales from 0 to 100.

RESULTS

There were no significant differences in changes in health-related quality of life over time between patients treated with hemodialysis (n=358) or hemodiafiltration (n=356). The quality of life domain patient satisfaction declined over time in both dialysis modalities (hemodialysis: -2.5/yr, -3.4 to -1.5, P<0.001; hemodiafiltration: -1.4/yr, -2.4 to -0.5, P=0.004).

CONCLUSIONS

Compared with hemodialysis, hemodiafiltration had no significant effect on quality of life over time.

Poor compliance with guidelines on anemia treatment in a cohort of chronic hemodialysis patients

BACKGROUND/AIMS

Guidelines for the management of anemia and iron deficiency in chronic hemodialysis (HD) patients have been developed to standardize therapy and improve clinical outcome. The present study evaluated compliance with anemia guidelines and investigated whether differences between centers were present.

METHODS

Data on anemia management from patients in the baseline cohort of the CONTRAST study (NCT00205556) were analyzed. 598 chronic HD patients (62% male, age 63.6 ± 14.0 years) from 26 Dutch dialysis centers were included.

RESULTS

Mean hemoglobin (Hb) level was 11.9 ± 1.3 g/dl and Hb was ≥11.0 g/dl in 81% of the patients. Compliance with all anemia targets (Hb 11.0-12.0 g/dl, transferrin saturation ratio ≥20%, ferritin 100-500 ng/ml) was reached in 11.6% (95% CI 7.8-17.0) of the patients, with a wide range among centers (4-26%, adjusted for case mix, treatment-related factors and center-specific characteristics).

CONCLUSION

Compliance with anemia targets in stable HD patients was poor and showed a wide variation between treatment facilities.

Hepcidin-25 in chronic hemodialysis patients is related to residual kidney function and not to treatment with erythropoiesis stimulating agents

Hepcidin-25, the bioactive form of hepcidin, is a key regulator of iron homeostasis as it induces internalization and degradation of ferroportin, a cellular iron exporter on enterocytes, macrophages and hepatocytes. Hepcidin levels are increased in chronic hemodialysis (HD) patients, but as of yet, limited information on factors associated with hepcidin-25 in these patients is available. In the current cross-sectional study, potential patient-, laboratory- and treatment-related determinants of serum hepcidin-20 and -25, were assessed in a large cohort of stable, prevalent HD patients. Baseline data from 405 patients (62% male; age 63.7 ± 13.9 [mean SD]) enrolled in the CONvective TRAnsport STudy (CONTRAST; NCT00205556) were studied. Predialysis hepcidin concentrations were measured centrally with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Patient-, laboratory- and treatment related characteristics were entered in a backward multivariable linear regression model. Hepcidin-25 levels were independently and positively associated with ferritin (p<0.001), hsCRP (p<0.001) and the presence of diabetes (p = 0.02) and inversely with the estimated glomerular filtration rate (p = 0.01), absolute reticulocyte count (p = 0.02) and soluble transferrin receptor (p<0.001). Men had lower hepcidin-25 levels as compared to women (p = 0.03). Hepcidin-25 was not associated with the maintenance dose of erythropoiesis stimulating agents (ESA) or iron therapy. In conclusion, in the currently studied cohort of chronic HD patients, hepcidin-25 was a marker for iron stores and erythropoiesis and was associated with inflammation. Furthermore, hepcidin-25 levels were influenced by residual kidney function. Hepcidin-25 did not reflect ESA or iron dose in chronic stable HD patients on maintenance therapy. These results suggest that hepcidin is involved in the pathophysiological pathway of renal anemia and iron availability in these patients, but challenges its function as a clinical parameter for ESA resistance.

Effect of online hemodiafiltration on all-cause mortality and cardiovascular outcomes

In patients with ESRD, the effects of online hemodiafiltration on all-cause mortality and cardiovascular events are unclear. In this prospective study, we randomly assigned 714 chronic hemodialysis patients to online postdilution hemodiafiltration (n=358) or to continue low-flux hemodialysis (n=356). The primary outcome measure was all-cause mortality. The main secondary endpoint was a composite of major cardiovascular events, including death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, therapeutic coronary intervention, therapeutic carotid intervention, vascular intervention, or amputation. After a mean 3.0 years of follow-up (range, 0.4-6.6 years), we did not detect a significant difference between treatment groups with regard to all-cause mortality (121 versus 127 deaths per 1000 person-years in the online hemodiafiltration and low-flux hemodialysis groups, respectively; hazard ratio, 0.95; 95% confidence interval, 0.75-1.20). The incidences of cardiovascular events were 127 and 116 per 1000 person-years, respectively (hazard ratio, 1.07; 95% confidence interval, 0.83-1.39). Receiving high-volume hemodiafiltration during the trial associated with lower all-cause mortality, a finding that persisted after adjusting for potential confounders and dialysis facility. In conclusion, this trial did not detect a beneficial effect of hemodiafiltration on all-cause mortality and cardiovascular events compared with low-flux hemodialysis. On-treatment analysis suggests the possibility of a survival benefit among patients who receive high-volume hemodiafiltration, although this subgroup finding requires confirmation.

Differences in quality of life of hemodialysis patients between dialysis centers

PURPOSE

Hemodialysis patients undergo frequent and long visits to the clinic to receive adequate dialysis treatment, medical guidance, and support. This may affect health-related quality of life (HRQOL). Although HRQOL is a very important management aspect in hemodialysis patients, there is a paucity of information on the differences in HRQOL between centers. We set out to assess the differences in HRQOL of hemodialysis patients between dialysis centers and explore which modifiable center characteristics could explain possible differences.

METHODS

This cross-sectional study evaluated 570 hemodialysis patients from 24 Dutch dialysis centers. HRQOL was measured with the Kidney Disease Quality Of Life-Short Form (KDQOL-SF).

RESULTS

After adjustment for differences in case-mix, three HRQOL domains differed between dialysis centers: the physical composite score (PCS, P = 0.01), quality of social interaction (P = 0.04), and dialysis staff encouragement (P = 0.001). These center differences had a range of 11-21 points on a scale of 0-100, depending on the domain. Two center characteristics showed a clinical relevant relation with patients' HRQOL: dieticians' fulltime-equivalent and the type of dialysis center.

CONCLUSION

This study showed that clinical relevant differences exist between dialysis centers in multiple HRQOL domains. This is especially remarkable as hemodialysis is a highly standardized therapy.

Capillary rarefaction in advanced chronic kidney disease is associated with high phosphorus and bicarbonate levels

BACKGROUND

In patients with chronic kidney disease (CKD), disorders of mineral metabolism are associated with vascular calcifications and mortality. Microvascular dysfunction, by affecting flow resistance and tissue perfusion, may explain the cardiovascular sequelae of CKD-associated disorders of mineral metabolism. We investigated whether advanced CKD is associated with a decrease in the functional and structural number of capillaries in skin and subsequently whether capillary rarefaction is related to mineral metabolism.

METHODS

Capillary density was measured by nailfold microscopy in 19 predialysis and 35 CKD Stage 5 (CKD5) patients and 19 controls. In CKD patients, calcium, phosphorus, parathyroid hormone, 25-hydroxyvitaminD3 (25vitD3) and 1,25-dihydroxyvitaminD3 (1,25vitD3) were analysed as well.

RESULTS

Capillary density at baseline was 42 ± 15/mm(2) in predialysis patients, 45 ± 17/mm(2) in CKD5 patients and 56 ± 20/mm(2) in controls (patients versus controls, respectively, P < 0.05 and P = 0.05). Absolute capillary recruitment during post-occlusive reactive hyperaemia was 17 ± 7/mm(2), 14 ± 6/mm(2) and 23 ± 8/mm(2), respectively (P < 0.05 for both patients and controls). Capillary density during venous occlusion was 59 ± 20/mm(2), 59 ± 21/mm(2) and 77 ± 21/mm(2), respectively (P < 0.05 for both patients and controls). In multiple regression analysis, both serum phosphorus and bicarbonate values were independently and inversely associated with capillary density at baseline (r(2) of model = 19%) as well as during venous occlusion (r(2) of model = 28%). Furthermore, both serum phosphorus and bicarbonate were inversely and female gender positively correlated with capillary density during recruitment (r(2) of model = 37%).

CONCLUSION

Advanced CKD is characterized by an impaired functional and structural capillary density in skin, which is related to both high phosphorus and bicarbonate values.

Changes in quality of life over time--Dutch haemodialysis patients and general population compared

BACKGROUND

Improving the health-related quality of life (HRQOL) for haemodialysis patients is a considerable challenge. The aim of the present study was to compare changes in HRQOL in haemodialysis patients with those observed in the general population over a 10-year period and explore factors that might explain possible differences.

METHODS

We compared 126 haemodialysis patients assessed in 1995 in the Netherlands Cooperative Study on the Adequacy of Dialysis-1 (NECOSAD-I) with 515 patients enrolled in 2006 in the ongoing Convective Transport Study (CONTRAST). Changes in HRQOL in these cohorts were compared with two representative samples from the general Dutch population, assessed in 1992 (n = 1,063) and 2001 (n = 10,600). HRQOL was measured with the SF-36 questionnaire. Differences in HRQOL were analysed with ANCOVA to adjust for demographic variables. To assess possible differences, we used multivariable regression analysis.

RESULTS

HRQOL in haemodialysis patients in 2006 [CONTRAST, mean age 63 ± 14 years (SD), 62% male] was significantly better than in 1995 (NECOSAD-I, 59 ± 16 years, 53% male) in four domains of the SF-36: bodily pain (+ 5 points, P = 0.009), vitality (+ 7, P < 0.001), role-emotional (+ 14, P < 0.001) and mental health (+ 8, P < 0.001), after adjusting for demographic variables. This increment could partly be explained by improved haemoglobin and phosphate levels. Compared to the general population, HRQOL improvement was most outspoken in two domains: bodily pain (+ 6, P = 0.01) and role-emotional (+ 8, P = 0.007).

CONCLUSIONS

This study showed an improvement of HRQOL in haemodialysis patients over an 11-year period of time, independent of global changes in the general population.

Role of residual renal function in phosphate control and anemia management in chronic hemodialysis patients

BACKGROUND AND OBJECTIVES

There is increasing awareness that residual renal function (RRF) has beneficial effects in hemodialysis (HD) patients. The aim of this study was to investigate the role of RRF, expressed as GFR, in phosphate and anemia management in chronic HD patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Baseline data of 552 consecutive patients from the Convective Transport Study (CONTRAST) were analyzed. Patients with a urinary output≥100 ml/24 h (n=295) were categorized in tertiles on the basis of degree of GFR and compared with anuric patients (i.e., urinary output<100 ml/24 h, n=274). Relations between GFR and serum phosphate and erythropoiesis-stimulating agent (ESA) index (weekly ESA dose per kg body weight divided by hematocrit) were analyzed with multivariable regression models.

RESULTS

Phosphate levels were between 3.5 and 5.5 mg/dl in 68% of patients in the upper tertile (GFR>4.13 ml/min per 1.73 m2), as compared with 46% in anuric patients despite lower prescription of phosphate-binding agents. Mean hemoglobin levels were 11.9±1.2 g/dl with no differences between the GFR categories. The ESA index was 31% lower in patients in the upper tertile as compared with anuric patients. After adjustments for patient characteristics, patients in the upper tertile had significantly lower serum phosphate levels and ESA index as compared with anuric patients.

CONCLUSIONS

This study suggests a strong relation between RRF and improved phosphate and anemia control in HD patients. Efforts to preserve RRF in HD patients could improve outcomes and should be encouraged.

Effect of hemodiafiltration on mortality, inflammation and quality of life

Online hemodiafiltration may improve clinical outcome in end-stage kidney disease. The supposed mechanism is the improved clearance of uremic toxins by the convective transport which is added to the standard diffusive transport. This review summarizes the effects of hemodiafiltration on mortality, inflammation and health-related quality of life.

Role of residual kidney function and convective volume on change in beta2-microglobulin levels in hemodiafiltration patients

BACKGROUND AND OBJECTIVES

Removal of beta2-microglobulin (beta2M) can be increased by adding convective transport to hemodialysis (HD). The aim of this study was to investigate the change in beta2M levels after 6-mo treatment with hemodiafiltration (HDF) and to evaluate the role of residual kidney function (RKF) and the amount of convective volume with this change.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Predialysis serum beta2M levels were evaluated in 230 patients with and 176 patients without RKF from the CONvective TRAnsport STudy (CONTRAST) at baseline and 6 mo after randomization for online HDF or low-flux HD. In HDF patients, potential determinants of change in beta2M were analyzed using multivariable linear regression models.

RESULTS

Mean serum beta2M levels decreased from 29.5 +/- 0.8 (+/-SEM) at baseline to 24.3 +/- 0.6 mg/L after 6 mo in HDF patients and increased from 31.9 +/- 0.9 to 34.4 +/- 1.0 mg/L in HD patients, with the difference of change between treatment groups being statistically significant (regression coefficient -7.7 mg/L, 95% confidence interval -9.5 to -5.6, P < 0.001). This difference was more pronounced in patients without RKF as compared with patients with RKF. In HDF patients, beta2M levels remained unchanged in patients with GFR >4.2 ml/min/1.73 m2. The beta2M decrease was not related to convective volume.

CONCLUSIONS

This study demonstrated effective lowering of beta2M levels by HDF, especially in patients without RKF. The role of the amount of convective volume on beta2M decrease appears limited, possibly because of resistance to beta2M transfer between body compartments.

Post-dilution haemodiafiltration and low-flux haemodialysis have dissimilar effects on platelets: a side study of CONTRAST

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in patients with end-stage renal disease (ESRD). Platelet (PLT) dysfunction, which is a well-known phenomenon in advanced chronic renal failure, corresponds positively with CVD in these patients. The accumulation of retained uraemic toxins might play an important role in this respect. During haemodialysis (HD), both an increase in the expression of the platelet (PLT) cell surface molecule P-selectin (CD62p) and the release of intra-granular substances, such as platelet factor 4 (PF4) and ss-thromboglobulin (BTG), have been described. As the removal of uraemic toxins is superior during haemodiafiltration (HDF), this form of treatment may have quite another impact on PLTs than HD.

METHODS

Nineteen chronic HD patients who were treated with low-flux HD for at least 2 months were included in the Dutch CONvective TRAnsport STudy (CONTRAST). After randomization, 10 patients continued low-flux HD and 9 patients switched to post-dilution HDF. The present study describes various parameters of PLT activation and degranulation at baseline (during HD) and after 3 months (during HDF) in the latter group of patients. At both time points, multiple blood samples were drawn. During the first 30 min of treatment, differences over the extracorporeal circuit (ECC) were calculated by taking samples from both afferent (arterial) and efferent (venous) lines. Correlations between various parameters were calculated in the total group of patients after 3 months.

RESULTS

Immediately after the start of HD, PLT counts dropped over the ECC. During HDF, PLT counts decreased even more and reached a nadir at t30. CD62p expression increased early during HD and returned to baseline thereafter. During HDF, these changes were more pronounced and more protracted. With respect to degranulation, rather dissimilar results were obtained. During HD, both PF4 and BTG increased over time, whereas during HDF, PF4 increased but BTG did not change. Haemoconcentration and transmembrane pressure (TMP) within the dialyser were, respectively, approximately 10 and 3x higher during HDF than during HD. There was a striking correlation between the changes in haemoconcentration and the changes in both PLT counts and CD62p over the ECC.

SUMMARY AND CONCLUSIONS

PLT activation, as measured by the expression of CD62p, was more pronounced and more protracted during HDF than during HD. During HDF, PLTs were trapped abundantly within the ECC, not only after first passage, but also thereafter. The degranulation product BTG increased during HD, but did not change during HDF. These observations may well be explained by the greater haemoconcentration and/or higher TMP during HDF on the one hand, and superior convective transport at the other. Whether the potential harmful effects of enhanced PLT activation are counterbalanced by the beneficial effects of an increased convective transport of degranulation products remains to be established.