Determinants of phosphorus mobilization during hemodialysis.

Our recent work proposed a pseudo one-compartment model for describing intradialysis and postdialysis rebound kinetics of phosphorus. In this model, phosphorus is removed directly from a central distribution volume with the rate of phosphorus mobilization from a second, very large compartment proportional to the phosphorus mobilization clearance. Here, we evaluated factors of phosphorus mobilization clearance and postdialysis central distribution volume from 774 patients in the HEMO Study. Phosphorus mobilization clearance and postdialysis central distribution volume were 87 (65, 116) ml/min, median (interquartile range), and 9.4 (7.2, 12.0) liter, respectively. The phosphorus mobilization clearance was significantly higher for male patients than for female patients. Both the phosphorus mobilization clearance and the postdialysis central distribution volume were significantly associated with postdialysis body weight but negatively with the predialysis serum phosphorus concentration. The postdialysis central distribution volume was also significantly associated with age. Overall, the postdialysis central distribution volume was 13.6% of the postdialysis body weight. Thus, the phosphorus mobilization clearance during hemodialysis is higher when predialysis serum phosphorus concentration is low and higher in male patients than in female patients. The central distribution volume of phosphorus is a space approximating the extracellular fluid volume.

A phase 3, randomized, double-blinded, active-controlled, unblinded standard of care study assessing the efficacy and safety of intramyocardial autologous CD34+ cell administration in patients with refractory angina: design of the RENEW study.

Preclinical trials indicate that CD34+ cells represent an effective angiogenic stem cell component. Early-phase clinical trials suggest that intramyocardial administration of autologous CD34+ cells may improve functional capacity and symptoms of angina. RENEW is a pivotal phase 3 trial designed to determine the efficacy of granulocyte colony-stimulating factor (G-CSF)-mobilized CD34+ stem cells for the treatment for patients with refractory angina and chronic myocardial ischemia. Patients (n = 444) receiving maximally tolerated antianginal therapies and lacking conventional revascularization options with Canadian Cardiovascular Society class III or IV angina and ischemia on stress testing will be randomized 2:1:1 to cell therapy (G-CSF-mediated stem cell mobilization, apheresis, and intramyocardial injection of 1 × 10(5) autologous CD34(+) cells/kg), active control (G-CSF-mediated stem cell mobilization, apheresis, and intramyocardial placebo injection), or open-label standard of care. The primary efficacy end point is change in exercise treadmill time in the treated vs active control patients, with 90% power to detect a 60-second difference in exercise time between cell-treated (n = 200) and active control (n = 100) patients. Key secondary end points include total number of anginal episodes per week and the incidence of independently adjudicated major adverse cardiac events and serious adverse events. RENEW will be the first adequately powered study aimed at definitively determining the efficacy of a cell therapy (intramyocardially delivered autologous CD34+ cells) for improvement of functional capacity in patients with refractory angina.

A randomized, controlled pilot study of autologous CD34+ cell therapy for critical limb ischemia.

BACKGROUND: Critical limb ischemia portends a risk of major amputation of 25% to 35% within 1 year of diagnosis. Preclinical studies provide evidence that intramuscular injection of autologous CD34+ cells improves limb perfusion and reduces amputation risk. In this randomized, double-blind, placebo-controlled pilot study, we evaluated the safety and efficacy of intramuscular injections of autologous CD34+ cells in subjects with moderate or high-risk critical limb ischemia, who were poor or noncandidates for surgical or percutaneous revascularization (ACT34-CLI). METHODS AND RESULTS: Twenty-eight critical limb ischemia subjects were randomized and treated: 7 to 1 × 10(5) (low-dose) and 9 to 1 × 10(6) (high-dose) autologous CD34+ cells/kg; and 12 to placebo (control). Intramuscular injections were distributed into 8 sites within the ischemic lower extremity. At 6 months postinjection, 67% of control subjects experienced a major or minor amputation versus 43% of low-dose and 22% of high-dose cell-treated subjects (P=0.137). This trend continued at 12 months, with 75% of control subjects experiencing any amputation versus 43% of low-dose and 22% of high-dose cell-treated subjects (P=0.058). Amputation incidence was lower in the combined cell-treated groups compared with control group (6 months: P=0.125; 12 months: P=0.054), with the low-dose and high-dose groups individually showing trends toward improved amputation-free survival at 6 months and 12 months. No adverse safety signal was associated with cell administration. CONCLUSIONS: This study provides evidence that intramuscular administration of autologous CD34+ cells was safe in this patient population. Favorable trends toward reduced amputation rates in cell-treated versus control subjects were observed. These findings warrant further exploration in later-phase clinical trials. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00616980.

Incidence and clinical significance of cardiac biomarker elevation during stem cell mobilization, apheresis, and intramyocardial delivery: an analysis from ACT34-CMI.

BACKGROUND: Cell therapy is a promising therapeutic for a variety of cardiovascular conditions including refractory angina. Elevation of cardiac biomarkers during cell delivery has been frequently described, but the clinical implications have never been studied. METHODS: ACT34-CMI was a randomized double-blind study assessing the use of intramyocardial delivery of autologous CD34(+) cells for the treatment of refractory angina. Patients (n = 167) underwent G-CSF-mediated (5 µg/[kg day] × 5 days) stem cell mobilization, apheresis, and intramyocardial injection of 1 × 10(5)/kg or 5 × 10(5)/kg CD34(+) cells or placebo. Troponin and creatinine kinase MB were assessed at baseline (n = 161), after cell mobilization and apheresis (n = 153 and 143, respectively), and post-intramyocardial injection (n = 155 and 141, respectively). Major adverse cardiac events (MACE) included death, myocardial infarction, acute congestive heart failure, urgent revascularization, or sustained ventricular arrhythmia. RESULTS: Seven (4.3%) subjects had troponin above the upper limits of normal (ULN) at baseline. Thirty-four (22.2%) and 11 (7.2%) subjects had troponin levels > ULN or >3× ULN after cell mobilization and apheresis, whereas 72 (46.1%) and 39 (25.2%) subjects had troponin elevations > ULN or >3× ULN, respectively, after intramyocardial injections. Age, but no other preprocedural factors, was predictive of troponin elevation. Periprocedural troponin elevation was not associated with an increased risk of MACE during 1 year, especially in cell therapy-treated patients. CONCLUSIONS: Troponin elevation is common during stem cell harvesting and intramyocardial administration, is usually asymptomatic, and does not appear to be associated with long-term MACE in subjects undergoing stem cell mobilization and intramyocardial injection.

Neighborhood location, rurality, geography, and outcomes of peritoneal dialysis patients in the United States.

BACKGROUND: The adjusted 5-year survival for dialysis patients in the United States is 33%-35%, and patients treated with peritoneal dialysis (PD) have a high risk of transfer to hemodialysis (HD). No data are available on the effect of neighborhood characteristics or regional differences on the outcomes of PD patients in the United States. METHODS: We analyzed the relationships of selected patient demographics, socio-economic characteristics of the dialysis unit's neighborhood, "rurality," and geographic location with transfer to HD and with a composite outcome of transfer to HD or death, for all PD patients in the United States who, between 2004 and 2009, used supplies manufactured by Baxter Healthcare (n = 58 700). RESULTS: Over a median follow-up of 18.7 months, 29% of patients transferred to HD (median time to HD transfer: 49 months), and 54% reached the composite outcome. More than 20% of the events occurred within the first 90 days of PD start. The risk for each of the study outcomes was higher for patients who had received any previous treatment with HD, for those treated in units located in areas with a higher proportion of black residents, and for those living in remote rural areas. Furthermore, the risk for reaching either of the study outcomes was consistently lower for patients treated in units located in California, Alaska, Hawaii, Guam, the Mariana Islands, and American Samoa. CONCLUSIONS: We observed significant regional differences in the outcomes of PD patients in the United States that have not previously been reported. Understanding the differences in clinical practice that underlie these regional differences might help to further improve PD outcomes.

Peritoneal dialysis technique success during the initial 90 days of therapy.

Comparisons of technique success by peritoneal dialysis (PD) modality have typically excluded the initial 90 days of therapy. We analyzed a database of 51,469 new PD starts from 2004 to 2008 in the United States. The analysis concentrated on the initial 90 days of therapy to determine technique success and the impact of the continuous ambulatory PD (CAPD) and automated PD (APD) modalities. Overall, 13.3% of patients stopped PD within 90 days. Of patients starting directly on APD, 14.3% stopped PD within 90 days. Of patients starting on CAPD, 12.6% stopped PD within 90 days, and 63.4% changed to APD within 90 days. Only 3.3% of the latter patients failed to reach 90 days of therapy. By comparison, technique failure occurred in 28.8% of those initiating with and remaining on CAPD. We conclude that initial training to perform CAPD, with timely transfer to APD within the first 3 months, was associated with the greatest technique success at 90 days. The reasons for that success are unclear, and further research should be directed to determining factors responsible. It is possible that patients trained initially to CAPD but converted to APD have a greater understanding of the total therapy, which improves confidence. Those converted to APD may be more appreciative of the lifestyle benefits of APD, which translates into improved compliance; alternatively, technical factors associated with APD may be responsible. Those technical factors may include improved catheter function in the recumbent position during APD or the reduced infection risk associated with just 2 connect/disconnect procedures in APD compared with 8 in CAPD.

Intramyocardial, autologous CD34+ cell therapy for refractory angina.

RATIONALE: A growing number of patients with coronary disease have refractory angina. Preclinical and early-phase clinical data suggest that intramyocardial injection of autologous CD34+ cells can improve myocardial perfusion and function. OBJECTIVE: Evaluate the safety and bioactivity of intramyocardial injections of autologous CD34+ cells in patients with refractory angina who have exhausted all other treatment options. METHODS AND RESULTS: In this prospective, double-blind, randomized, phase II study (ClinicalTrials.gov identifier: NCT00300053), 167 patients with refractory angina received 1 of 2 doses (1×10(5) or 5×10(5) cells/kg) of mobilized autologous CD34+ cells or an equal volume of diluent (placebo). Treatment was distributed into 10 sites of ischemic, viable myocardium with a NOGA mapping injection catheter. The primary outcome measure was weekly angina frequency 6 months after treatment. Weekly angina frequency was significantly lower in the low-dose group than in placebo-treated patients at both 6 months (6.8±1.1 versus 10.9±1.2, P=0.020) and 12 months (6.3±1.2 versus 11.0±1.2, P=0.035); measurements in the high-dose group were also lower, but not significantly. Similarly, improvement in exercise tolerance was significantly greater in low-dose patients than in placebo-treated patients (6 months: 139±151 versus 69±122 seconds, P=0.014; 12 months: 140±171 versus 58±146 seconds, P=0.017) and greater, but not significantly, in the high-dose group. During cell mobilization and collection, 4.6% of patients had cardiac enzyme elevations consistent with non-ST segment elevation myocardial infarction. Mortality at 12 months was 5.4% in the placebo-treatment group with no deaths among cell-treated patients. CONCLUSIONS: Patients with refractory angina who received intramyocardial injections of autologous CD34+ cells (10(5) cells/kg) experienced significant improvements in angina frequency and exercise tolerance. The cell-mobilization and -collection procedures were associated with cardiac enzyme elevations, which will be addressed in future studies.

Health-related quality of life and hemoglobin levels in chronic kidney disease patients.

BACKGROUND: The relationship between quality of life (QofL) and anemia has been the subject of recent debates; it has been suggested that the QofL changes associated with the treatment of anemia of chronic kidney disease (CKD) or ESRD patients should not be used in making decisions to treat anemia in CKD patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study examines the relationship between Kidney Disease Quality of Life (KDQofL) questionnaire domains and hemoglobin (Hgb) levels in 1200 patients with stage 3, 4, and 5 CKD followed in seven centers. QofL measures were compared in a stepwise fashion for hemoglobin levels of <11, 11 to <12, 12 to <13, and > or =13. ANOVA was used to examine the relationship between QofL scores and Hgb level, age, CKD stage, and albumin level; a history of diabetes, congestive heart failure, or myocardial infarction; use of erythropoetic-stimulating agents (ESA); and the interaction of hemoglobin level and ESA. RESULTS: The results demonstrate that with increasing Hgb levels there is a statistically significant increase in all four physical domains, the energy/vitality domain, and the physical composite score of the SF-36, and the general health score on the kidney disease component of the questionnaire. The most dramatic improvements in these various domains occurred between the <11 and the 11 to 12 group. CONCLUSIONS: Higher Hgb levels are associated with improved QofL domains of the KDQofL questionnaire. These findings have implications for the care of CKD patients in terms of the initiation of and the Hgb target of ESA therapy.

Perceived knowledge among patients cared for by nephrologists about chronic kidney disease and end-stage renal disease therapies.

The need to educate patients in order to enable them to participate in making appropriate choices for all therapeutic options in end stage renal disease would seem obvious yet there are many barriers to providing such information. We measured 'perceived knowledge' of the therapeutic options for end stage renal disease in a cohort of patients with chronic kidney disease in established treatment programs. A self administered questionnaire was given to 676 patients with stage 3-5 chronic kidney disease as part of the CRIOS study designed to identify trends in practice patterns and outcomes over a 4 year period. The median patient age was 66, about three-fourths were Caucasian and almost half were diabetic. When patients were asked to rate their level of knowledge, about one-third reported limited or no understanding of their chronic kidney disease and no awareness regarding their treatment options. A significant and substantial number of patients indicated they had no familiarity with transplant, hemodialysis, and continuous ambulatory or automated peritoneal dialysis. Perceived knowledge improved with the progression of kidney disease and frequency of nephrology visits; however, only about half of patients with 4 or more nephrology appointments in the prior year reported knowing of hemodialysis, continuous ambulatory peritoneal dialysis or transplant. Age, gender and disease had no impact on levels of patient knowledge, but African-Americans reported having significantly less understanding than Asians or Caucasians. These findings suggest that the lack of perception concerning the treatment options chronic kidney and end stage renal disease reflects, in part, problems with the education of patients by nephrologists and not a lack of referral of these patients to nephrologists for care. The discrepancy of perceived knowledge between African-Americans and other races needs special attention.

Modeling of icodextrin in PD Adequest 2.0.

OBJECTIVE: To validate the use of a modified three-pore model for predicting fluid transport during long dwell exchanges that use a 7.5% icodextrin solution. DESIGN: A nonrandomized, single group, repeated measures study. PATIENTS: Ten peritoneal dialysis patients underwent a single 8-hour exchange of a 7.5% icodextrin solution. All patients were naive to icodextrin. MAIN OUTCOME MEASURES: A modified three-pore model was used to model solute and fluid transport during each 8-hour exchange. Concordance correlation coefficients were used to estimate the level of agreement between modeled and measured values of net ultrafiltration (UF) and intraperitoneal volume. METHODS: Each patient underwent a modified 8-hour standard peritoneal permeability analysis using a 2-L 7.5% icodextrin exchange. Dextran 70 was added to the icodextrin solution as volume marker to estimate fluid transport kinetics. Transcapillary UF, fluid absorption, and intraperitoneal volumes were assessed via the volume marker at 0, 5, 15, 30, 60, 120, 240, 300, 360, 420, and 480 minutes. RESULTS: There was strong agreement (concordance correlation = 0.9856) between net UF as measured by the volume marker data and net UF as modeled using the modified three-pore model implemented in PD Adequest (Baxter Healthcare, Deerfield, Illinois, USA). CONCLUSIONS: Net UF and intraperitoneal volumes for long dwell exchanges using a 7.5% icodextrin solution can be accurately modeled with a modified three-pore model. Steady state icodextrin plasma levels are needed to accurately predict net UF for chronic users of icodextrin.