Frequent Hemodialysis Network Research Articles

Association of Diabetes with Changes in Blood Pressure during Hemodialysis: A Secondary Analysis of the Frequent Hemodialysis Network Daily Trial

Plain Language SummaryAmong patients requiring maintenance hemodialysis (HD), those with diabetes experience higher rates of cardiovascular mortality, compared to those without diabetes. Intra-dialytic hypotension is common among patients receiving maintenance HD, but data on differential patterns of peri-HD blood pressure (BP) control according to the presence or absence of diabetes remain sparse. In this post hoc analysis of the Frequent Hemodialysis Network Daily Trial, we observed that patients with diabetes (vs. none) had similar pre- and post-HD but lower nadir, systolic BP. Further, we observed that the risk of intra-dialytic hypotension associated with diabetes was higher among patients with higher pre-HD BP. Knowledge of diabetes status and assessment of the pre-HD systolic BP may help identify patients at higher risk for intra-dialytic hypotension.

Association of Bioimpedance Parameters with Increases in Blood Pressure during Hemodialysis.

Intradialytic hypertension, defined as an increase in BP from pre- to post-hemodialysis (HD), affects 5%-15% of patients receiving maintenance HD and is associated with cardiovascular and all-cause mortality. Hypervolemia is believed to be a major etiological factor, yet the association of more objective biomarkers of volume status with intradialytic hypertension is not well described. In a post hoc analysis of the Frequent Hemodialysis Network Daily Trial ( n =234), using data from baseline, 1-, 4-, and 12-month visits ( n =800), we used random-effects regression to assess the association of bioimpedance estimates of volume (vector length) with post-HD systolic BP (continuous) and any increase in systolic BP (categorical) from pre- to post-HD. We adjusted models for randomized group; age; sex; self-reported race; Quételet (body mass) index; vascular access; HD vintage; hypertension; history of heart failure; diabetes; residual kidney function (urea clearance); pre-HD systolic BP; ultrafiltration rate; serum-dialysate sodium gradient; and baseline values of hemoglobin, phosphate, and equilibrated Kt/V urea. The mean age of participants was 50±14 years, 39% were female, and 43% were Black. In adjusted models, shorter vector length (per 50 Ω/m) was associated with higher post-HD systolic BP (2.9 mm Hg; 95% confidence interval [CI], 1.6 to 4.3) and higher odds of intradialytic hypertension (odds ratio 1.66; 95% CI, 1.07 to 2.55). Similar patterns of association were noted with a more stringent definition of intradialytic hypertension (>10 mm Hg increase from pre- to post-HD systolic BP), where shorter vector length (per 50 Ω/m) was associated with a higher odds of intradialytic hypertension (odds ratio 2.17; 95% CI, 0.88 to 5.36). Shorter vector length, a bioimpedance-derived proxy of hypervolemia, was independently associated with higher post-HD systolic BP and risk of intradialytic hypertension.

Association of Bioimpedance Parameters with Changes in Blood Pressure During Hemodialysis: A Secondary Analysis of the Frequent Hemodialysis Network (FHN) Daily Trial

Association of Bioimpedance Parameters with Changes in Blood Pressure During Hemodialysis: A Secondary Analysis of the Frequent Hemodialysis Network (FHN) Daily Trial

Contextualizing the FHN Nocturnal Trial a Decade Later: How Nocturnal Home Hemodialysis Is Performed Matters to Outcomes.

Long, frequent hemodialysis (HD) was thought to be a sound treatment because of improved clearance of uremic toxins and control of extracellular fluid volume. After all, no solute or volume control is tantamount to no dialysis, and whatever its shortcomings, dialysis does keep people alive. The

The Predialysis Serum Sodium Level Modifies the Effect of Hemodialysis Frequency on Left-Ventricular Mass: The Frequent Hemodialysis Network Trials

Introduction: The Frequent Hemodialysis Network (FHN) Daily and Nocturnal trials aimed to compare the effects of hemodialysis (HD) given 6 versus 3 times per week. More frequent in-center HD significantly reduced left-ventricular mass (LVM), with more pronounced effects in patients with low urine volumes. In this study, we aimed to explore another potential effect modifier: the predialysis serum sodium (SNa) and related proxies of plasma tonicity. Methods: Using data from the FHN Daily and Nocturnal Trials, we compared the effects of frequent HD on LVM among patients stratified by SNa, dialysate-to-predialysis serum-sodium gradient (GNa), systolic and diastolic blood pressure, time-integrated sodium-adjusted fluid load (TIFL), and extracellular fluid volume estimated by bioelectrical impedance analysis. Results: In 197 enrolled subjects in the FHN Daily Trial, the treatment effect of frequent HD on ∆LVM was modified by SNa. When the FHN Daily Trial participants are divided into lower and higher predialysis SNa groups (less and greater than 138 mEq/L), the LVM reduction in the lower group was substantially higher (−28.0 [95% CI −40.5 to −15.4] g) than in the higher predialysis SNa group (−2.0 [95% CI −15.5 to 11.5] g). Accounting for GNa, TIFL also showed more pronounced effects among patients with higher GNa or higher TIFL. Results in the Nocturnal Trial were similar in direction and magnitude but did not reach statistical significance. Discussion/Conclusion: In the FHN Daily Trial, the favorable effects of frequent HD on left-ventricular hypertrophy were more pronounced among patients with lower predialysis SNa and higher GNa and TIFL. Whether these metrics can be used to identify patients most likely to benefit from frequent HD or other dialytic or nondialytic interventions remains to be determined. Prospective, adequately powered studies studying the effect of GNa reduction on mortality and hospitalization are needed.

Equations to Estimate the Normalized Creatinine Generation Rate (CGRn) in 3/Week Dialysis Patients With or Without Residual Kidney Function

Normalized creatinine generation rate (CGRn) can be computed for a variety of dialysis schedules using a recently described kinetic modeling program. However, the availability of estimating equations might facilitate broader study of this metric. We developed equations to estimate CGRn based on modeling and then tested them against modeled CGRn values in the Frequent Hemodialysis Network Nocturnal Trial baseline (3/week) dataset. We used a "what-if" derivation of a previously published variable volume 2-pool creatinine kinetic model to generate predicted predialysis values of serum creatinine that would result from creatinine generation rates of 250-2000mg/day in patients with creatinine distribution volumes of 20 to 50L, dialyzed from 60 to 480min per treatment three times a week. Then, in patients with residual kidney function, we calculated an "anuric expected predialysis serum creatinine value" before applying the same equations. We then compared estimated CGRn values as predicted by this approach with modeled values in patient data from the Frequent Hemodialysis Network Nocturnal Trial. The estimating equations for CGRn yielded results similar to those obtained with formal modeling, in both anuric patients and those with residual kidney function, with mean percent error of 0.845±6.15 (SD) in anuric patients, and ‒0.29±4.90 in patients with a mean creatinine clearance of 5.44±4.82mL/min, with R-squared values of 0.96 in both anuric patients and those with residual renal clearance of creatinine. In patients dialyzed 3/week, CGRn can be estimated using prediction equations. Use of these equations may facilitate broader investigation of CGRn as a measure of nutritional status and outcome.

The effect of frequent hemodialysis on matrix metalloproteinases, their tissue inhibitors, and FGF23: Implications for blood pressure and left ventricular mass modification in the Frequent Hemodialysis Network trials.

Frequent hemodialysis modifies serum phosphorus, blood pressure, and left ventricular mass (LVM). We ascertained whether frequent hemodialysis is associated with specific changes in biomarker profile among patients enrolled in the frequent hemodialysis network (FHN) trials. This was a post hoc analysis of biomarkers among patients enrolled to the FHN trials. In particular, we hypothesized that frequent hemodialysis is associated with changes in a specific set of biomarkers which are linked with changes in blood pressure or LVM. Among 332 randomized patients, 243 had biomarker data available. Of these, 124 patients were assigned to 3-times-a-week hemodialysis (94 [Daily Trial] and 30 [Nocturnal Trial]) and 119 patients were assigned to 6-times-a-week hemodialysis (87 [Daily Trial] and 32 [Nocturnal Trial]). Frequent hemodialysis lowered phosphate, blood pressures, LVM, log fibroblast growth factor (FGF)23, and tissue inhibitors of metalloproteinase (TIMP)-2 levels. The fall in phosphate was associated with changes in FGF23 (r = 0.48, P < 0.001) [Daily Trial] and (r = 0.55, P < 0.001) [Nocturnal Trial]) and tended to be associated with changes in systolic blood pressure (r = 0.18, P = 0.057) [Daily Trial] and (r = 0.31, P = 0.04) [Nocturnal Trial]. Within the Daily Trial, changes in MMP2 (r = 0.20, P = 0.034) were associated with changes in LVM. In the Nocturnal Trial, changes in TIMP-1 (r = 0.37, P = 0.029) and MMP 9 (r = -0.38, P = 0.01) were associated with LVM changes. MMP2 changes were associated with changes in systolic blood pressure. Reduction of serum phosphate by frequent hemodialysis may modulate FGF23 levels and systolic blood pressure. Markers of matrix turnover are associated with LVM changes. Frequent hemodialysis may affect pathological mediators of chronic kidney disease-mineral bone-metabolism disorder.

The effect of increased frequency of hemodialysis on vitamin C concentrations: an ancillary study of the randomized Frequent Hemodialysis Network (FHN) daily trial

BackgroundReports on vitamin C in HD patients have shown effects of vitamin C deficiency in association with scurvy symptoms. Dialyzability of water soluble vitamins is high, and substantial losses in those who are dialyzed more frequently were hypothesized. The randomized FHN Daily Trial compared the effects of in-center HD six versus three times per week. We studied baseline correlations between vitamin C and potentially associated parameters, and the effect of more frequent HD on circulating vitamin C concentrations.MethodsWe studied vitamin C levels at baseline and months, 3, 5 and 11. Patients enrolled between 2007 and 2009 into the randomized FHN Daily trial in the East Coast consortium were approached for participation. Predialysis plasma samples were processed with metaphosphoric acid and frozen at − 70 °C for measurement with HPLC. Regression models between baseline log-transformed vitamin C and hemoglobin, CRP, eKt/V, ePCR and PTH, and a linear mixed-effects model to estimate the effect size of more frequent HD on plasma vitamin C, were constructed.ResultsWe studied 44 subjects enrolled in the FHN Daily trial (50 ± 12 years, 36% female, 29% Hispanics and 64% blacks, 60% anuric). Vitamin C correlated significantly with predialysis hemoglobin (r = 0.3; P = 0.03) and PTH (r = − 0.3, P = 0.04), respectively. Vitamin C did not significantly differ at baseline (6×/week, 25.8 ± 25.9 versus 3×/week, 32.6 ± 39.4 μmol/L) and no significant treatment effect on plasma vitamin C concentrations was found [− 26.2 (95%CI -57.5 to 5.1) μmol/L at Month 4 and − 2.5 (95%CI -15.6 to 10.6) μmol/L at Month 12.ConclusionsBased on data from this large randomized-controlled trial no significant effect of the intervention on circulating plasma vitamin C concentrations was found, allaying the concerns that more frequent HD would affect the concentrations of water-soluble vitamins and adversely affect patient’s well-being. Correlations between vitamin C and hemoglobin and PTH support the importance of vitamin C for normal bone and mineral metabolism, and anemia management.

The effect of increased frequency of hemodialysis on serum cystatin C and β2-microglobulin concentrations: A secondary analysis of the frequent hemodialysis network (FHN) trial.

Small molecular weight toxin clearance is the main method of assessment of hemodialysis efficiency. Middle molecules including cystatin C (CysC) and Beta-2 microglobulin (β2-M) are understudied. We hypothesized that lowering of predialysis CysC and β2-M serum concentrations would be affected by switching to more frequent hemodialysis. Predialysis CysC and β2-M serum concentrations were measured from serum samples of the Frequent Hemodialysis Network (FHN) Daily and Nocturnal Trials. The differences between predialysis concentrations at baseline (while on conventional thrice weekly dialysis) and those after 12-months of study (on more frequent dialysis) were compared separately by trial (Nocturnal, Daily). We tested the associations between predialysis serum CysC and β2-M concentrations and outcomes. Forty-nine percent and 52% of the patients from the FHN Daily and Nocturnal Trials respectively were included in this ancillary study. Predialysis serum CysC concentrations remained unchanged after intensifying hemodialysis dose by either modality. There was significant lowering of the serum β2-M concentrations in the frequent Daily Trial hemodialysis group at 12 months in all patients and in patients without residual renal function at baseline (-3.8 ± 12.62 μg/mL, P = 0.004; -5.9 ± 12.99 μg/mL, P = 0.02, respectively). There were no significant differences between the baseline and the 12-months predialysis β2-M serum concentrations in the two control groups (Daily 3× and Nocturnal 3× groups). No association between the changes in the two biomarkers between baseline and 12-months and in changes in left ventricular mass, physical-health composite scores, hospitalization rate, and death were found. The numbers of hospitalizations and deaths were small. β2-M may be a better biomarker of dialysis dose than CysC. Reduction in the concentration of potentially toxic long-lived proteins of the size of β-2M is one potential long-term benefit of more intensive dialysis that may be explored.

Changes in Biomarker Profile and Left Ventricular Hypertrophy Regression: Results from the Frequent Hemodialysis Network Trials

Background: Regression of left ventricular hypertrophy (LVH) is feasible with more frequent hemodialysis (HD). We aimed to ascertain pathways associated with regression of left ventricular mass (LVM) in patients enrolled in the Frequent HD Network (FHN) trials. Methods: This was a post hoc observational cohort study. We hypothesized LVH regression with frequent HD was associated with a different cardiovascular biomarker profile. Regressors were defined as patients who achieved a reduction of more than 10% in LVM at 12 months. Progressors were defined as patients who had a minimum of 10% increase in LVM at 12 months. Results: Among 332 randomized patients, 243 had biomarker data available. Of these, 121 patients did not progress or regress, 77 were regressors, and 45 were progressors. Mean LVM change differed between regressors and progressors by –65.6 (–74.0 to –57.2) g, p < 0.001. Regressors had a median (interquartile range) increase in dialysis frequency (from 3.0 [3.0–3.0] to 4.9 [3–5.7] per week, p = 0.001) and reductions in pre-dialysis systolic (from 149.0 [136.0–162.0] to 136.0 [123.0–152.0] mm Hg, p < 0.001) and diastolic (from 83.0 [71.0–91.0] to 76.0 [68.0–84.0] mm Hg, p < 0.001) blood pressures. Klotho levels increased in regressors versus progressors (76.9 [10.5–143.3] pg/mL, p = 0.024). Tissue inhibitors of metalloproteinase (TIMP)-2 levels fell in regressors compared to progressors (–7,853 [–14,653 to –1,052] pg/mL, p = 0.024). TIMP-1 and log (brain natriuretic ­peptide [BNP]) levels also tended to fall in regressors. Changes in LVM correlated inversely with changes in klotho (r = –0.24, p = 0.014). ­Conclusions: Markers of collagen turnover and changes in klotho levels are potential novel pathways associated with regression of LVH in the dialysis population, which will require further prospective validation.

More frequent hemodialysis does not effectively clear protein-bound azotemic solutes derived from gut microbiome metabolism

The 5-year survival rate for hemodialysis patients remains lower than that for some of the more common solid organ cancers. Trials of increasing urea clearance by hemodialysis have failed to demonstrate improved patient survival. Accumulating evidence suggests that protein-bound azotemic solutes derived from gut microbiome metabolism have greater potential for toxicity than urea. The Frequent Hemodialysis Network Trials group now report that increasing dialysis frequency to 6 times a week did not effectively improve clearance of these protein-bound azotemic solutes compared with standard thrice weekly sessions.

Thyroid function in end stage renal disease and effects of frequent hemodialysis.

End-stage renal disease (ESRD) is associated with perturbations in thyroid hormone concentrations and an increased prevalence of hypothyroidism. Few studies have examined the effects of hemodialysis dose or frequency on endogenous thyroid function. Within the Frequent Hemodialysis Network (FHN) trials, we examined the prevalence of hypothyroidism in patients with ESRD. Among those with endogenous thyroid function (without overt hyper/hypothyroidism or thyroid hormone supplementation), we examined the association of thyroid hormone concentration with multiple parameters of self-reported health status, and physical and cognitive performance, and the effects of hemodialysis frequency on serum thyroid stimulating hormone (TSH), free thyroxine (FT4), and free tri-iodothyronine (FT3) levels. Conventional thrice-weekly hemodialysis was compared to in-center (6 d/wk) hemodialysis (Daily Trial) and Nocturnal (6 nights/wk) home hemodialysis (Nocturnal Trial) over 12 months. Among 226 FHN Trial participants, the prevalence of hypothyroidism was 11% based on thyroid hormone treatment and/or serum TSH ≥8 mIU/mL. Among the remaining 195 participants (147 Daily, 48 Nocturnal) with endogenous thyroid function, TSH concentrations were modestly (directly) correlated with age (r = 0.16, P = 0.03) but not dialysis vintage. Circulating thyroid hormone levels were not associated with parameters of health status or physical and cognitive performance. Furthermore, frequent in-center and nocturnal hemodialysis did not significantly change (baseline to month 12) TSH, FT4, or FT3 concentrations in patients with endogenous thyroid function. Among patients receiving hemodialysis without overt hyper/hypothyroidism or thyroid hormone treatment, thyroid indices were not associated with multiple measures of health status and were not significantly altered with increased dialysis frequency.

Limited reduction in uremic solute concentrations with increased dialysis frequency and time in the Frequent Hemodialysis Network Daily Trial

The Frequent Hemodialysis Network Daily Trial compared conventional three-times weekly treatment to more frequent treatment with a longer weekly treatment time in patients receiving in-center hemodialysis. Evaluation at one year showed favorable effects of more intensive treatment on left ventricular mass, blood pressure, and phosphate control, but modest or no effects on physical or cognitive performance. The current study compared plasma concentrations of uremic solutes in stored samples from 53 trial patients who received three-times weekly in-center hemodialysis for an average weekly time of 10.9 hours and 30 trial patients who received six-times weekly in-center hemodialysis for an average of 14.6 hours. Metabolomic analysis revealed that increased treatment frequency and time resulted in an average reduction of only 15 percent in the levels of 107 uremic solutes. Quantitative assays confirmed that increased treatment did not significantly reduce levels of the putative uremic toxins p-cresol sulfate or indoxyl sulfate. Kinetic modeling suggested that our ability to lower solute concentrations by increasing hemodialysis frequency and duration may be limited by the presence of non-dialytic solute clearances and/or changes in solute production. Thus, failure to achieve larger reductions in uremic solute concentrations may account, in part, for the limited benefits observed with increasing frequency and weekly treatment time in Frequent Hemodialysis Daily Trial participants.

Intensive Hemodialysis and Potential Risks With Increasing Treatment

Although intensive hemodialysis (HD) can address important clinical problems, increasing treatment also introduces risks. In this review, we assess risks pertaining to 6 domains: vascular access complications, infection, mortality, loss of residual kidney function, solute balance, and patient and care partner burden. In the Frequent Hemodialysis Network (FHN) trials, short daily and nocturnal schedules increased the incidence of access complications, although the incidence of access loss was not statistically higher. Observational studies indicate that infection-related hospitalization is an ongoing challenge with short daily HD. Excess risk may be catalyzed by poor infection control practices in the home setting in which intensive HD is typically delivered, but with fixed probability of bacterial contamination per cannulation, greater treatment frequency necessarily increases the risk for infectious complications. Buttonhole cannulation may increase the risk for metastatic infections. However, intensive HD in the home setting is associated with lower risk for infection than peritoneal dialysis. Data regarding mortality are equivocal. With extended follow-up of individuals in the FHN trials, short daily HD was associated with lower risk relative to the usual schedule, whereas nocturnal HD was associated with higher risk. In many, but not all, observational studies, short daily HD has been associated with lower risk than both in-center HD and peritoneal dialysis; however, observational studies are subject to unmeasured confounding. Intensive HD can accelerate the loss of residual kidney function in new dialysis patients with substantial urine output and can deplete solutes (eg, phosphorus) to the extent that supplementation is necessary. Finally, intensive HD may increase burden on patients and caregivers, possibly leading to technique failure. Some of these problems might be addressed with careful monitoring, so that relevant interventions (eg, antibiotics, retraining, and respite care) can be delivered. Ultimately, intensive HD is not a panacea for end-stage renal disease. Potential benefits and risks of treatment should be jointly considered.

Intensive Hemodialysis, Mineral and Bone Disorder, and Phosphate Binder Use

Mineral and bone disorder is a common complication of end-stage renal disease. Notably, hyperphosphatemia likely promotes calcification of the myocardium, valves, and arteries. Hyperphosphatemia is associated with higher risk for cardiovascular mortality and morbidity along a gradient beginning at 5.0mg/dL. Among contemporary hemodialysis (HD) patients, mean serum phosphorus level is 5.2mg/dL, although 25% of patients have serum phosphorus levels of 5.5 to 6.9mg/dL; and 13%, >7.0mg/dL. Treatment of hyperphosphatemia is burdensome. Dialysis patients consume a mean of 19 pills per day, half of which are phosphate binders. Medicare Part D expenditures on binders for dialysis patients approached $700 million in 2013. Phosphorus removal with thrice-weekly HD (4 hours per session) is ∼3,000mg/wk. However, clearance is unlikely to counterbalance dietary intake, which varies around a mean of 7,000mg/wk. Dietary restriction and phosphate binders are important interventions, but each has limitations. Dietary control is complicated by limited access to healthy food choices and unclear labeling. Meanwhile, adherence to phosphate binders is poor, especially in younger patients and those with high pill burden. Multiple randomized clinical trials show that intensive HD reduces serum phosphorus levels. In the Frequent Hemodialysis Network (FHN) trial, short daily and nocturnal schedules reduced serum phosphorus levels by 0.6 and 1.6mg/dL, respectively, relative to 3 sessions per week. A similar effect of nocturnal HD was observed in an earlier trial. In the daily arm of the FHN trial, intensive HD significantly lowered estimated phosphate binder dose per day, whereas in the nocturnal arm, intensive HD led to binder discontinuation in 75% of patients. However, intensive HD appears to have no meaningful effects on serum calcium and parathyroid hormone concentrations. In conclusion, intensive HD, especially nocturnal HD, lowers serum phosphorus levels and decreases the need for phosphate binders.

Intensive Hemodialysis and Treatment Complications and Tolerability

Hemodialysis (HD) treatment can be difficult to tolerate. Common complications are intradialytic hypotension (IDH) and long time to recovery after an HD session. IDH, as defined by nadir systolic blood pressure <90mmHg and intradialytic decline > 30mmHg, occurs in almost 8% of HD sessions. IDH may be caused by aggressive ultrafiltration in response to interdialytic weight gain, can lead to myocardial stunning and cardiac arrhythmias, and is associated with increased risk for death. Long recovery time after a treatment session is also common. In DOPPS (Dialysis Outcomes and Practice Patterns Study), recovery time was 2 to 6 hours for 41% of HD patients and longer than 6 hours for 27%; recovery time was linearly associated with increased risks for death and hospitalization. Importantly, both decreases in blood pressure and feeling washed out or drained have been identified by patients as more important outcomes than death or hospitalization. Intensive HD likely reduces the likelihood of IDH. In the Frequent Hemodialysis Network trial, short daily and nocturnal schedules reduced the per-session probability of IDH by 20% and 68%, respectively, relative to 3 sessions per week. Due to lower ultrafiltration volume and/or rate, intensive HD may reduce intradialytic blood pressure variability. In a cross-sectional study, short daily and nocturnal schedules were associated with slower ultrafiltration and less dialysis-induced myocardial stunning than 3 sessions per week. In FREEDOM (Following Rehabilitation, Economics, and Everyday-Dialysis Outcome Measurements), a prospective cohort study of short daily HD, recovery time was reduced after 12 months from 8 hours to 1 hour, according to per-protocol analysis. Recovery time after nocturnal HD may be minutes. In conclusion, intensive HD can improve the tolerability of HD treatment by reducing the risk for IDH and decreasing recovery time after HD. These changes may improve the patient centeredness of end-stage renal disease care.

Intensive Hemodialysis, Left Ventricular Hypertrophy, and Cardiovascular Disease

The prevalence of cardiovascular disease, including cardiac arrhythmia, coronary artery disease, cardiomyopathy, and valvular heart disease, is higher in hemodialysis (HD) patients than in the US resident population. Cardiovascular disease is the leading cause of death in HD patients and the principal discharge diagnosis accompanying 1 in 4 hospital admissions. Furthermore, the rate of hospital admissions for either heart failure or fluid overload is persistently high despite widespread use of β-blockers and renin-angiotensin system inhibitors and attempts to manage fluid overload with ultrafiltration. An important predictor of cardiovascular mortality and morbidity in dialysis patients is left ventricular hypertrophy (LVH). LVH is an adaptive response to increased cardiac work, typically caused by combined pressure and volume overload, resulting in cardiomyocyte hypertrophy and increased intercellular matrix. In new dialysis patients, the prevalence of LVH is 75%. Regression of LVH may reduce cardiovascular risk, including the incidence of heart failure, complications after myocardial infarction, and sudden arrhythmic death. Multiple randomized clinical trials show that intensive HD reduces left ventricular mass, a measure of LVH. Short daily and nocturnal schedules in the Frequent Hemodialysis Network trial reduced left ventricular mass by 14 (10%) and 11 (8%) g, respectively, relative to 3 sessions per week. Comparable efficacy was observed in an earlier trial of nocturnal HD. Intensive HD also improves cardiac rhythm. Clinical benefits have been reported only in observational studies. Daily home HD is associated with 17% and 16% lower risks for cardiovascular death and hospitalization, respectively; admissions for cerebrovascular disease, heart failure, and hypertensive disease, which collectively constitute around half of cardiovascular hospitalizations, were less likely with daily home HD. Relative to peritoneal dialysis, daily home HD is likewise associated with lower risk for cardiovascular hospitalization. In conclusion, intensive HD likely reduces left ventricular mass and may lead to lower risks for adverse cardiacevents.

Intensive Hemodialysis, Blood Pressure, and Antihypertensive Medication Use

Hypertension is a cardinal feature of end-stage renal disease (ESRD). Hypertensive nephropathy is the primary cause of ESRD for nearly 30% of patients, and the prevalence of hypertension is >85% in new patients with ESRD. In contemporary hemodialysis (HD) patients, mean predialysis systolic blood pressure (SBP) is nearly 150mmHg, and about 70%, 50%, and 40% use β-blockers, calcium channel blockers, and renin-angiotensin system inhibitors, respectively. Predialysis SBP generally exhibits a U-shaped association with mortality risk. Interdialytic ambulatory SBP is more strongly associated with risk. Hypertension is multifactorial; key causes include persistent hypervolemia and elevated peripheral resistance. With 3 HD sessions per week, blood pressure (BP) climbs during the interdialytic interval, in step with interdialytic weight gain, particularly among elderly patients and those with higher dry weight. Elevated peripheral resistance can be attributed to inappropriate activation of the sympathetic nervous system due to higher plasma norepinephrine concentrations. Multiple randomized clinical trials show that intensive HD reduces BP and the need for oral medications indicated for hypertension. In the first 2 months of the Frequent Hemodialysis Network trial, the short daily schedule reduced predialysis SBP by 7.7mmHg, whereas the nocturnal schedule reduced predialysis SBP by 7.3mmHg, both relative to 3 sessions per week. Improvements were sustained after 12 months. Both schedules reduced antihypertensive medication use relative to 3 sessions per week. In FREEDOM (Following Rehabilitation, Economics, and Everyday-Dialysis Outcome Measurements), a prospective cohort study of short daily HD, the mean number of prescribed antihypertensive agents decreased from 1.7 to 1.0 in 1 year, whereas the percentage of patients not prescribed antihypertensive agents increased from 21% to 47%. Nocturnal HD appears to markedly reduce total peripheral resistance and plasma norepinephrine and restore endothelium-dependent vasodilation. In conclusion, intensive HD reduces BP and the need for antihypertensive medications.

The effect of frequent hemodialysis on self-reported sleep quality: Frequent Hemodialysis Network Trials.

Many patients who receive maintenance hemodialysis experience poor sleep. Uncontrolled studies suggest frequent hemodialysis improves sleep quality, which is a strong motivation for some patients to undertake the treatment. We studied the effects of frequent in-center ('daily') and nocturnal home hemodialysis on self-reported sleep quality in two randomized trials. Participants were randomly assigned to frequent (six times per week) or conventional (three times per week) hemodialysis in the Frequent Hemodialysis Network Daily (n = 245) and Nocturnal (n = 87) Trials. We used the Medical Outcomes Study Sleep Problems Index II (SPI II), a validated and reliable instrument in patients with end-stage renal disease, to measure self-reported sleep quality. The SPI II is scored from 0-100, with a higher value indicating poorer quality of sleep. A mean relative decline in SPI II would suggest improved sleep quality. The primary sleep outcome was the change in the SPI II score over 12 months. In the Daily Trial, after adjustment for baseline SPI II, subjects randomized to frequent as compared with conventional in-center hemodialysis experienced a 4.2 [95% confidence interval (CI) 0.4-8.0] point adjusted mean relative decline in SPI II at 4 months and a 2.6 (95% CI -2.3-7.5) point adjusted mean relative decline at 12 months. In the Nocturnal Trial, subjects randomized to frequent nocturnal as compared with conventional home hemodialysis experienced 2.9 (95% CI -3.4-9.3) and 4.5 (95% CI -3.2-12.2) point mean relative declines at Months 4 and 12, respectively. Although a possible benefit of frequent in-center hemodialysis was observed at 4 months, neither frequent in-center hemodialysis nor home nocturnal hemodialysis demonstrated significant improvements in self-reported sleep quality compared with conventional hemodialysis at 12 months.

Cognitive changes associated with switching to frequent nocturnal hemodialysis or renal transplantation.

BackgroundIt is uncertain whether switching to frequent nocturnal hemodialysis improves cognitive function in well-dialyzed patients and how this compares to patients who receive a kidney transplant.MethodsWe conducted a multicenter observational study with longitudinal follow-up of the effect on cognitive performance of switching dialysis treatment modality from conventional thrice-weekly hemodialysis to frequent nocturnal hemodialysis, a functioning renal transplant or remaining on thrice-weekly conventional hemodialysis. Neuropsychological tests of memory, attention, psychomotor processing speed, executive function and fluency as well as measures of solute clearance were performed at baseline and again after switching modality. The change in cognitive performance measured by neuropsychological tests assessing multiple cognitive domains at baseline, 4 and 12 months after switching dialysis modality were analyzed using a linear mixed model.ResultsSeventy-seven patients were enrolled; 21 of these 77 patients were recruited from the randomized Frequent Hemodialysis Network (FHN) Nocturnal Trial. Of these, 18 patients started frequent nocturnal hemodialysis, 28 patients received a kidney transplant and 31 patients remained on conventional thrice-weekly hemodialysis. Forty-eight patients (62 %) returned for the 12-month follow-up. Despite a significant improvement in solute clearance, 12 months treatment with frequent nocturnal hemodialysis was not associated with substantial improvement in cognitive performance. By contrast, renal transplantation, which led to near normalization of solute clearance was associated with clinically relevant and significant improvements in verbal learning and memory with a trend towards improvements in psychomotor processing speed. Cognitive performance in patients on conventional hemodialysis remained stable with the exception of an improvement in psychomotor processing speed and a decline in verbal fluency.ConclusionsIn patients on conventional thrice-weekly hemodialysis, receiving a functioning renal transplant was associated with improvement in auditory-verbal memory and psychomotor processing speed, which was not observed after 12 months of frequent nocturnal hemodialysis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-016-0223-9) contains supplementary material, which is available to authorized users.