Relationship among catheter insertions, vascular access infections, and anemia management in hemodialysis patients

Incidence and challenges in management of hemodialysis catheter-related infections

Catheter-related infections (CRI) are a major cause of morbidity and mortality in chronic hemodialysis (HD) patients. In this paper, we share our experience with CRI in HD patients. We recorded 49 cases of CRI among 167 patients during a period of 40 months (January 2018-April 2021). The incidence of CRI was 3.7 per 1000 catheter-days. The revealing symptoms were dominated by fever or chills (90%). Inflammatory signs were observed in 74% of cases with respectively concurrent exit-site (51%) and tunnel infection (6%). The biological inflammatory syndrome was found in 74% of patients (average CRP level = 198.9 mg/l). Blood cultures were performed in all cases and were positive in 65% of cases. Thirteen patients have been diagnosed with Infection complications, which were respectively infective endocarditis in 7 cases, septic arthritis in 3 cases, infective myositis in one case, cerebral thrombophlebitis in 1 case and mediastinitis in 1 case. The death occurred in eleven patients, it was due to septic shock in 9 cases, pulmonary embolism in one case and neurologic alterations related to cerebral thrombophlebitis. The mean seniority in HD was 16.5 months in the group with CRI and 3.7 months in the group without CRI (p < 0.04). We did not notice significant difference in mortality between tunnelled and non-tunnelled catheters. CRI does not seem to be more severe in patients with diabetes. Duration of use of the HD catheter (p < 0.007) and ferritin level (p < 0.0001) were independent factors that predispose to CRI in our population.

Clinical significance of a novel reticulocyte-based erythropoietin resistance index in HD patients: A retrospective study

INTRODUCTION

The erythropoietin resistance index (ERI) is an indicator of erythropoiesis-stimulating agent (ESA) responsiveness and is typically calculated using Hb. However, Hb does not directly reflect ESA-induced erythropoiesis because of its long-term nature. We thus designed a novel ERI calculated with reticulocyte Hb (RetHb), a real-time index, and investigated its association with mortality in HD patients.

METHODS

We calculated the ERI using the change in RetHb before and after ESA administration (ERI_ΔRetHb ) and retrospectively analyzed its association with 3-year all-cause mortality using Kaplan-Meier survival curves and Cox regression analyses.

RESULTS

A total of 102 patients were included. Patients with the highest ERI_ΔRetHb had the worst prognosis according to the Kaplan-Meier survival curves (Log-rank p = 0.02). Multivariate Cox regression analysis showed that the ERI_ΔRetHb was significantly and independently associated with all-cause mortality (hazard ratio: 9.82, 95% CI [1.50, 64.41], p = 0.02).

CONCLUSION

The ERI_ΔRetHb was significantly and independently associated with all-cause mortality in HD patients.

Effect of sutureless securement on hemodialysis catheter-related bloodstream infection

The use of sutureless securement devices during catheterization might reduce the risk of catheter-related bloodstream infection (CRBSI) by suppressing catheter-exit infection and catheter dislodgement. However, the effectiveness of these devices in reducing CRBSI risk when securing hemodialysis catheters has not been explored. This single-center retrospective observational study examined 211 non-tunneled hemodialysis catheters (NTHCs) from 110 hemodialysis inpatients, of which 121 were secured using conventional skin sutures (Suture group) and 90 with GRIP-LOK (GRIP-LOK group). The stabilized inverse probability of treatment (SIPT)-weighting method was used to generate a new population (SIPT-weighted model) without group differences for each of the 12 predictors of CRBSI development (i.e., age, sex, dialysis history, concomitant acute kidney injury or diabetes, concurrent use of immunosuppressant drugs or aspirin, NTHC insertion site, methicillin-resistant Staphylococcus aureus, carriage, bacteremia event within 3 months before catheterization, hemoglobin level, and serum albumin titer). The effect of GRIP-LOK compared with sutures on CRBSI in the SIPT-weighted model was evaluated using univariate SIPT-weighted Cox proportional regression analysis, which showed a significant CRBSI suppression effect of GRIP-LOK compared with sutures (hazard ratio: 0.17 [95% CI 0.04–0.78], p = 0.023).　GRIP-LOK affords a lower risk of CRBSI due to indwelling NTHCs than conventional securement using sutures.

Managing Anemia across the Stages of Kidney Disease in Those Hyporesponsive to Erythropoiesis-Stimulating Agents

BACKGROUND

Patients with CKD frequently have anemia that results from iron-restricted erythropoiesis and inflammation. Anemia of CKD is currently managed with iron supplements and erythropoiesis-stimulating agents (ESAs) to promote erythropoiesis and with RBC transfusion in severe cases. Hyporesponse to ESAs, or the need for larger than usual doses to attain a given hemoglobin (Hb) level, is associated with increased morbidity and mortality and presents a pressing clinical challenge, particularly for patients on dialysis. This paper reviews ESA hyporesponse and potential new therapeutic options in the management of anemia of CKD.

SUMMARY

The most common causes of ESA hyporesponse include iron deficiency and inflammation, and to a lesser degree, secondary hyperparathyroidism, inadequate dialysis, malnutrition, and concomitant medications. Management of ESA hyporesponse is multipronged and involves treating low level infections, ensuring adequate nutrition, and optimizing iron status and dialysis modality, although some patients can remain refractory. Inflammation directly increases production and secretion of hepcidin, contributes to an impaired response to hypoxia, and suppresses proliferation of erythroid progenitors. Coordination of renal and hepatic erythropoietin (EPO) production and iron metabolism is under the control of hypoxia-inducible factors (HIF), which are in turn regulated by HIF-prolyl hydroxylases (HIF-PHs). HIF-PHs and hepcidin are therefore attractive potential drug targets particularly in patients with ESA hyporesponse. Several oral HIF-PH inhibitors have been evaluated in patients with anemia of CKD and have been shown to increase Hb and reduce hepcidin regardless of inflammation, iron status, or dialysis modality. These sustained effects are achieved through more modest increases in endogenous EPO compared with ESAs. Key Messages: Treatments that address ESA hyporesponse remain a significant unmet clinical need in patients with anemia of CKD. New therapies such as HIF-PH inhibitors have the potential to address fundamental aspects of ESA hyporesponse and provide a new therapeutic option in these patients.

Longitudinal assessments of erythropoietin-stimulating agent responsiveness and the association with specific clinical outcomes in dialysis patients

BACKGROUND

Dose requirements of erythropoietin-stimulating agents (ESAs) can vary considerably over time and may be associated with cardiovascular outcomes. We aimed to longitudinally assess ESA responsiveness over time and to investigate its association with specific clinical end points in a time-dependent approach.

METHODS

The German Diabetes and Dialysis study (4D study) included 1,255 diabetic dialysis patients, of whom 1,161 were receiving ESA treatment. In those patients, the erythropoietin resistance index (ERI) was assessed every 6 months during a median follow-up of 4 years. The association between the ERI and cardiovascular end points was analyzed by time-dependent Cox regression analyses with repeated ERI measures.

RESULTS

Patients had a mean age of 66 ± 8.2 years; 53% were male. During follow-up, a total of 495 patients died, of whom 136 died of sudden death and 102 of infectious death. The adjusted and time-dependent risk for sudden death was increased by 19% per 5-unit increase in the ERI (hazard ratio, HR = 1.19, 95% confidence interval, CI = 1.07-1.33). Similarly, mortality increased by 25% (HR = 1.25, 95% CI = 1.18-1.32) and infectious death increased by 27% (HR = 1.27, 95% CI = 1.13-1.42). Further analysis revealed that lower 25-hydroxyvitamin D levels were associated with lower ESA responsiveness (p = 0.046).

CONCLUSIONS

In diabetic dialysis patients, we observed that time-varying erythropoietin resistance is associated with sudden death, infectious complications and all-cause mortality. Low 25-hydroxyvitamin D levels may contribute to a lower ESA responsiveness.

Pretransplantation erythropoiesis-stimulating agent hyporesponsiveness is associated with increased kidney allograft failure and mortality

BACKGROUND

Poor response to erythropoiesis-stimulating agents (ESA) is associated with morbidity and mortality among dialysis patients. It is unclear whether the risk associated with poor ESA response during dialysis extends beyond kidney transplantation. We examined pretransplantation ESA response and its effect on allograft failure and mortality.

METHODS

The cohort included all adult Medicare recipients from the U.S. Renal Data System who had received a kidney transplant during years 2000 to 2007 and had at least 6 months of hemodialysis immediately before transplantation. ESA hyporesponsiveness was primarily defined as a monthly ESA dose of 75,000 units or higher and hematocrit 33% or less for at least 3 consecutive months in the pretransplantation period. Crude and adjusted Cox proportional hazards models and Kaplan-Meier methods were used to estimate the effect of ESA hyporesponsiveness on allograft failure and all-cause mortality.

RESULTS

The study group consisted of 36,450 patients; 1004 exhibited hyporesponsiveness. The adjusted hazard ratios (95% confidence interval) for allograft failure and mortality after transplantation were 1.23 (1.10-1.42) and 1.61 (1.43-1.81), respectively, supporting that poor ESA response during hemodialysis is associated with adverse posttransplantation outcomes.

CONCLUSIONS

ESA hyporesponsiveness may be useful in identifying potential allograft recipients who are at high risk for subsequent morbidity and mortality and may benefit from more intensive pretransplantation and posttransplantation monitoring.

Iron and infection in hemodialysis patients

Intravenous iron is an important component of the treatment of anemia of end-stage renal disease (ESRD), but it is biologically plausible that iron could increase the risk of infection through impairment of neutrophil and T-cell function and promotion of microbial growth. Any such increase in risk would be particularly important because infection is a significant cause of mortality and morbidity in dialysis patients. The overall evidence favors an association between iron and infection in hemodialysis patients, but the optimal iron management strategy to minimize infection risk has yet to be identified. There is a need for further research on this topic, particularly in light of increased utilization of intravenous iron following implementation of the bundled ESRD reimbursement system.

Disparities in arteriovenous fistula placement in older hemodialysis patients

The benefits of an arteriovenous fistula (AVF) as the preferred vascular access for hemodialysis have been clearly demonstrated. However, only about 20% of patients in the United States initiate hemodialysis with an AVF. In this study, we assessed whether disparities exist in the type of first hemodialysis access placed prior to dialysis start (rather than that used at dialysis initiation), to detect whether certain disadvantaged groups might have lower likelihood of AVF placement. Study cohort of 118,767 incident hemodialysis patients ≥67 years of age (1/2005-12/2008) derived from the United States Renal Data System was linked with Medicare claims data to identify the type of initial access placed predialysis. We used logistic regression model with outcome being the initial predialysis placement of an AVF as opposed to an arteriovenous graft or a central venous catheter. Increasing age, female sex, black race, lower body mass index, urban location, certain comorbidities, and shorter pre-end-stage renal disease nephrology care are all associated with a significantly lower likelihood of AVF placement as initial access predialysis. Our study suggests the presence of significant disparities in the placement of an AVF as initial hemodialysis vascular access. We suggest that additional attention should be paid to these patient groups to improve disparities by patient education, earlier referral, and close follow-up.

A Novel Electrospun Nano-fabric Graft Allows Early Cannulation Access and Reduces Exposure to Central Venous Catheters

Purpose

The use of tunneled central venous catheters (CVC) as vascular access for hemodialysis treatment is increasing worldwide. We present a novel polycarbonate urethane nano-fabric graft, produced by electrospinning technology, which has self-sealing features that avoid seroma formation and allow puncturing within 48 hours. The aim of this study was to assess its advantages in a setting where late referral is common.

Methods

A retrospective single center study assessed 24 implanted grafts in 24 patients with maximal follow-up of 18 months; patency rates, time to first cannulation and post-operative complications were assessed.

Results

Successful access was achieved in all 24 patients within 48 hours. In 50% of the patients cannulation was performed within 24 hours without increasing the complication rate. Twelve month primary and secondary patencies were 50% and 70.8%, respectively. Excluding early failures (within 30 days) because of surgical problems, 12 month primary and secondary patencies were 75% and 81.2% respectively. Complication and infection rates were 10.94 and 0.49/1000 dialysis procedures, respectively. No pseudoaneurysms or seromas were documented at 18 months.

Conclusions

Early cannulation was successful in all patients with good 12-month primary and secondary patency rates, compared to data reported by others on polytetrafluoroethylene (PTFE) grafts. The infection rate was substantially lower than in tunneled CVCs. Therefore, the AVflo graft may improve the clinical status of dialysis patients by decreasing the exposure to CVCs.

The IMPACT (Incident Management of Patients, Actions Centered on Treatment) program: a quality improvement approach for caring for patients initiating long-term hemodialysis

BACKGROUND

Patients beginning dialysis therapy are at risk of death and illness. The IMPACT (Incident Management of Patients, Actions Centered on Treatment) quality improvement program was developed to improve incident hemodialysis patient outcomes through standardized care.

STUDY DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

Patients who started hemodialysis therapy between September 2007 and December 2008 at DaVita facilities using the IMPACT program (n = 1,212) constituted the intervention group. Propensity score-matched patients who initiated hemodialysis therapy in the same interval at DaVita facilities not using the IMPACT program (n = 2,424) made up the control group.

QUALITY IMPROVEMENT PLAN

IMPACT intervention included a structured intake process and monitoring reports; patient enrollment in a 90-day patient education program and 90-day patient management pathway.

OUTCOMES

Mean dialysis adequacy (Kt/V), hemoglobin and albumin levels, percentage of patients using preferred vascular access (arteriovenous fistula or graft), and mortality at each quarter.

RESULTS

Compared with the non-IMPACT group, the IMPACT group was associated with a higher proportion of patients dialyzing with a preferred access at 90 days (0.50 [95% CI, 0.47-0.53] vs 0.47 [95% CI, 0.45-0.49]; P = 0.1) and 360 days (0.63 [95% CI, 0.61-0.66] vs 0.48 [95% CI, 0.46-0.50]; P < 0.001) and a lower mortality rate at 90 days (24.8 [95% CI, 19.0-30.7] vs 31.9 [95% CI, 27.1-36.6] deaths/100 patient-years; P = 0.08) and 360 days (17.8 [95% CI, 15.2-20.4] vs 25.1 [95% CI, 20.7-25.2] deaths/100 patient-years; P = 0.01).

LIMITATIONS

The study does not determine the care processes responsible for the improved outcomes.

CONCLUSIONS

Intense management of incident dialysis patients with the IMPACT quality improvement program was associated with significantly decreased first-year mortality. Focused attention to the care of incident patients is an important part of a dialysis program.

Variant hemoglobin phenotypes may account for differential erythropoiesis-stimulating agent dosing in African-American hemodialysis patients

African-American patients with end-stage renal disease have historically lower hemoglobin concentrations and higher requirements of erythropoiesis-stimulating agent (ESA). While disparities in health-care access may partially explain these findings, the role of variant hemoglobin, such as sickle trait, has not been investigated. To clarify this, we evaluated 154 African-American patients receiving in-center hemodialysis with available hemoglobin phenotyping. The primary exposure was any abnormal hemoglobin variant and the primary outcome of higher-dose ESA was defined as a dose of 6500 or more units per treatment. Logistic regression assessed the association between variant hemoglobin and higher-dose ESA. Covariates included age, gender, diabetes, iron parameters, intravenous iron dose, parathyroid hormone, albumin, phosphorus, body mass index, vascular access type, hospitalization/missed treatments, smoking status, alcohol abuse, and gastrointestinal bleeding. Of 33 patients with variant hemoglobin, 24 had HbAS and 9 had HbAC. Univariate odds of higher-dose ESA among those with hemoglobin variants were twice that of those with the normal HbAA phenotype (odds ratio 2.05). In multivariate models, the likelihood of higher-dose ESA had an odds ratio of 3.31 and the nature of this relationship did not change in Poisson regression or sensitivity analyses. Hence, our findings may explain, in part, the difference in ESA dosing between Caucasians and African-Americans with end-stage renal disease but await further study.

The effect of altitude change on anemia treatment response in hemodialysis patients

Hemodialysis patients who live at high altitude use less exogenous erythropoietin but achieve higher hematocrit levels than those living at a lower altitude. The authors hypothesized that the effect of altitude would be strongest in hemodialysis patients with poor anemia treatment response. To explore this hypothesis, they studied anemia-related outcomes in US hemodialysis patients who move to higher altitudes. Using Medicare and US Geological Survey data, in 1992-2004 they identified instances in which a patient moved from a dialysis center at an altitude of <2,000 feet (600 m) to one at a higher elevation. Of these moves, 5,274 were ≥3,000 feet (900 m; the altitude group) and 25,345 were 250-500 feet (75-150 m; the control group). Among patients with poor treatment response at baseline, large increases in hematocrit and decreases in erythropoietin dosing were observed in the altitude relative to the control group. At 6 months, hematocrit had increased more in the altitude group (5.1%, 95% confidence interval (CI): 4.1, 6.2 vs. 3.7%, 95% CI: 3.5, 3.9), and erythropoietin dosing decreased more (4,600 units/week, 95% CI: 500, 8,700 vs. 1,700 units/week, 95% CI: 1,000, 2,400). No effect of altitude was observed in patients with better treatment response at baseline. These results support the hypothesis that altitude-induced hypoxia reduces erythropoietin requirements in hemodialysis patients with treatment-refractory anemia.

Hemoglobin variability and mortality: confounding by disease severity

BACKGROUND

Substantial variability in hemoglobin levels has been associated with increased mortality risk in hemodialysis patients. Variability also has been associated with concurrent comorbid conditions and hospitalization. Adequate adjustment for confounding by disease severity is needed to estimate the association of hemoglobin level variability with mortality risk.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Medicare hemodialysis patients in 3 groups: prevalent on July 1, 2006 (n = 133,246), prevalent on July 1, 1996 (n = 78,602), and incident between January 1, 2005, and June 30, 2006 (n = 24,999).

PREDICTOR

Hemoglobin level variability estimated using the residual deviation around the linear trend in hemoglobin levels during a 6-month entry period.

OUTCOME

Time to death.

MEASUREMENTS

We fit Cox models of 1-year mortality with and without adjustment for disease severity (comorbid conditions, hospitalization days, and months with hemoglobin level <10 g/dL), measured concurrently with hemoglobin level variability.

RESULTS

Disease severity was associated positively with hemoglobin level variability in all groups. Before adjustment for disease severity, HRs for hemoglobin level variability were 1.27 (95% CI, 1.24-1.31) per 1 g/dL for patients prevalent in 2006, 1.32 (95% CI, 1.27-1.38) for patients prevalent in 1996, and 1.08 (95% CI, 1.03-1.13) for patients incident in 2005-2006. After adjustment, HRs for hemoglobin level variability were 1.02 (95% CI, 0.99-1.05), 1.07 (95% CI, 1.03-1.12), and 1.01 (95% CI, 0.95-1.06), respectively.

LIMITATIONS

We did not adjust for time-varying confounding of hemoglobin level; an inclusion requirement introduces potential selection bias; our findings may not apply to incident hemodialysis patients younger than 65 years; assessment of comorbid conditions from claims is subject to misclassification, with possible residual confounding attributable to comorbid conditions; this observational study cannot prove causality.

CONCLUSIONS

After adjustment for concurrent disease severity, evidence supporting an association between hemoglobin level variability and mortality risk was weak and inconsistent. The clinical utility of hemoglobin level variability may be limited.

Greater Epoetin alfa (EPO) doses and short-term mortality risk among hemodialysis patients with hemoglobin levels less than 11 g/dL

PURPOSE

We examined the association between high doses of Epoetin alfa (EPO), which are used to raise and maintain hemoglobin (Hb) levels within target ranges for hemodialysis patients, and short-term mortality risk using multivariable regression and an instrumental variable (IV) analysis.

METHODS

We identified 32 734 patients receiving hemodialysis in 786 facilities from a large US dialysis provider between July 2000 and March 2002 who received care for >4 consecutive months, and had an Hb < 11 g/dL in the third month. We assessed dose titrations following the Hb < 11 g/dL and characterized facilities based on the percentage of patients with dose titrations >25% (instrument). We assessed deaths during the subsequent 90 days and evaluated the EPO dose-mortality association using conventional linear and IV regression.

RESULTS

The study population had a mean (SD) age of 60.4 (15.0) years; 48% were white, 42% were black and 51% were male. In unadjusted analyses, high EPO doses were associated with 90-day mortality risk (Risk Difference, RD = 3.0 per 100 persons, 95%CI:2.3-3.6); mortality risk was attenuated after adjustment for confounding (RD = 1.5 per 100 persons, 95%CI:0.8-2.2) and not associated with high EPO dose in the pooled IV analysis, though confidence intervals (CI) were wide (RD = -0.4 per 100 persons, 95%CI:-3.2-2.4).

CONCLUSIONS

The difference in risk estimates between the adjusted linear regression and the IV regression suggests that the short-term mortality related to EPO dosing may be largely attributable to confounding-by-indication for higher doses. The IV method, which was employed to address the possibility of residual confounding, yielded near null though imprecise effect estimates.

Relationship between epoetin alfa dose and mortality: findings from a marginal structural model

BACKGROUND AND OBJECTIVES

Observational studies relating epoetin alfa (EPO) dose and mortality frequently use analytic methods that do not control time-dependent confounding by indication (CBI). The relationship between EPO dose and 1-year mortality, adjusting for the effects of time-dependent CBI, was examined using a marginal structural model.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective cohort study included 27,791 hemodialysis patients between July 2000 and June 2002. Patients were grouped at successive 2-wk intervals into a zero-dose category or four nonzero-dose categories. Ordinal regression was used to calculate inverse probability of treatment weights of patients receiving their own dose level given their covariate and treatment history. Three treatment models with an increasing number of treatment predictors were evaluated to assess the effect of model specification. A small number of excessively large patient weights were truncated. Relative hazards for higher-dose groups compared with the lowest nonzero-dose group varied by treatment model specification and by level of weight truncation.

RESULTS

Results differed appreciably between the simplest treatment model, which incorporated only hemoglobin and EPO dosing history with 2% weight truncation (hazard ratio: 1.51; 95% confidence interval: 1.09, 1.89 for highest-dose patients), and the most comprehensive treatment model with 1% weight truncation (hazard ratio: 0.98; 95% confidence interval: 0.76, 1.74).

CONCLUSIONS

There is appreciable CBI at higher EPO doses, and EPO dose was not associated with increased mortality in marginal structural model analyses that more completely addressed this confounding.

Evolving statistical methods to facilitate evaluation of the causal association between erythropoiesis-stimulating agent dose and mortality in nonexperimental research: strengths and limitations

Findings from randomized controlled trials examining the efficacy of therapy with erythropoiesis-stimulating agents (ESAs) to normalize hemoglobin levels in patients with chronic kidney disease or kidney failure have raised questions regarding the safety of this class of drugs. However, no trial to date has specifically assessed the safety of ESA-dosing algorithms used to achieve the lower hemoglobin targets typically using in clinical practice. Although a wealth of nonexperimental data is available for dialysis patients, analyses based on these data are more susceptible to confounding bias than randomized controlled trials. Conducting valid pharmacoepidemiologic studies of drug effects in hemodialysis patients is complicated by the extent of their comorbidities, frequent hospitalizations, various concomitant medications, and an exceedingly high mortality rate. The need for greater ESA doses for the treatment of anemia in sicker patients potentially and plausibly generates confounding by indication, the control of which is complicated by the presence of time-dependent confounding. Here, we describe sources of bias in nonexperimental studies of ESA therapy in hemodialysis patients and critically appraise analytical methods that may help minimize bias in such studies.

Effect of Epoetin alfa dose changes on hemoglobin and mortality in hemodialysis patients with hemoglobin levels persistently below 11 g/dL

BACKGROUND AND OBJECTIVES

The mortality risk associated with attempting to raise hemoglobin (Hb) levels by increasing Epoetin alfa (EPO) doses in hemodialysis patients with persistently low Hb remains poorly understood. Design, setting, participants, & measurements. We included hemodialysis patients from a large dialysis provider between July 2000 and June 2001 who had EPO dose and Hb data for 6 consecutive months, and a mean Hb <11 g/dl in months 4 to 6 (sub-11 period). We identify predictors of EPO dose changes during the sub-11 period; evaluate the proportion of patients achieving a Hb >or=11 g/dl after the sub-11 period by dose-change categories; and evaluate the association between EPO dose changes and mortality risk.

RESULTS

Patients were more likely to receive greater EPO dose increases if they had lower EPO doses, higher Hb levels, or were recently hospitalized. Greater EPO dose increases elevated the likelihood of achieving an Hb >or=11 g/dl in the subsequent 3 mo. Larger EPO dose changes over the sub-11 period were not associated with an elevated mortality risk, but having an Hb <9 g/dl at the end of that period independent of dose change was associated with mortality risk. We found that patients receiving larger dose changes and whose resulting Hb level remained <9.5 g/dl at the end of the 3 mo were at elevated mortality risk.

CONCLUSIONS

In patients with persistently low Hb levels, mortality risk was strongly associated with the patient's ability to achieve a hematopoietic response rather than the magnitude of EPO dose titrations.

Hyporesponsiveness to erythropoietin: causes and management

In patients with chronic kidney disease, erythropoietin resistance is common, costly, and has implications beyond the management of anemia because the presence of erythropoietin resistance portends mortal outcomes. Exploring the provenance of erythropoietin resistance may be facilitated by the consideration of the pathogenetic triad of iron-restricted erythropoiesis, inflammation, and bone marrow suppression. Challenging to diagnose because of difficulty in interpreting tests of iron deficiency, iron-restricted erythropoiesis should be considered in patients who require high doses of erythropoietin, have low transferrin saturation (eg, <20%-25%), and do not have very high ferritin (eg, <1,200 ng/mL); a therapeutic trial of intravenous iron may be worthwhile. Aluminum intoxication is a rare cause of iron-restricted erythropoiesis that may manifest as microcytic hypochromic anemia. A decrease in serum albumin concentration may signal the presence of inflammation, which may be manifest (such as because of a recent illness or infection) or occult; the latter include clotted synthetic angioaccess, failed renal allograft, dialysis catheter, periodontal disease, underlying malignancy, or uremia per se. Marrow hyporesponsiveness may be improved by increasing the delivered dialysis dose, using ultrapure dialysate, maintaining adequate vitamin B12 and folate stores, or by treating hyperparathyroidism. In summary, improving the outcomes of erythropoietin-resistant patients will require complete patient assessment that goes beyond considerations of iron and erythropoietin dose alone. Given that erythropoietin dose is associated with mortality, mitigating erythropoietin resistance has the potential to improve patient outcomes.

Analyses of age, gender and other risk factors of erythropoietin resistance in pediatric and adult dialysis cohorts

Previous studies often report lower responses to erythropoietin (EPO) therapy in pediatric patients on chronic dialysis than those of adults. Because of the greater capacity for hematopoiesis in the younger population, these studies may be confounded by poorly identified variables. Thus, we made parallel studies of pediatric and adult cohorts to explore the relationship between age, gender and other risk factors with EPO resistance. Thirty pediatric subjects (aged 8-20 years) and 66 adult subjects (aged 22-85 years) on chronic hemodialysis and EPO were enrolled. After stratification by 50th percentile of EPO response, the best predictive model was identified by backward elimination of the risk factors with the least contribution to the regression. Relationship between age, gender and EPO resistance was examined by analysis of covariance (ANCOVA). The most predictive model of EPO response for the pediatric cohort had, as the major variables, urea clearance x dialysis duration/total body water (Kt/V), urea reduction ratio (URR), intact parathyroid hormone (iPTH), blood loss, normalized protein catabolic rates (nPCR) and indices of malnutrition and inflammation, whereas adults had iron and folate deficiencies as the dominant variables. Although EPO resistance was more common in female subjects than in male subjects, relationship with neither age nor gender was significant. Furthermore, the prescription of a larger (initiating) EPO dose by pediatric physicians compared with adult nephrologists confounded the interaction between age and EPO resistance. In summary EPO resistance in the pediatric dialysis cohort was predicted by nutritional deficits, inflammation, poor dialysis, and hyperparathyroidism, while iron and folate deficits were the major determinants in adults. Although confounded by the pattern of EPO prescription, neither age nor gender was predictive of EPO resistance in the two study groups.

Facility hemodialysis vascular access use and mortality in countries participating in DOPPS: an instrumental variable analysis

BACKGROUND

Previously, the Dialysis Outcomes and Practice Patterns Study (DOPPS) has shown large international variations in vascular access practice. Greater mortality risks have been seen for hemodialysis (HD) patients dialyzing with a catheter or graft versus a native arteriovenous fistula (AVF). To further understand the relationship between vascular access practice and outcomes, we have applied practice-based analyses (using an instrumental variable approach) to decrease the treatment-by-indication bias of prior patient-level analyses.

STUDY DESIGN

A prospective observational study of HD practices.

SETTING & PARTICIPANTS

Data collected from 1996 to 2004 from 28,196 HD patients from more than 300 dialysis units participating in the DOPPS in 12 countries.

PREDICTOR OR FACTOR

Patient-level or case-mix-adjusted facility-level vascular access use. OUTCOMES/MEASUREMENTS: Mortality and hospitalization risks.

RESULTS

After adjusting for demographics, comorbid conditions, and laboratory values, greater mortality risk was seen for patients using a catheter (relative risk, 1.32; 95% confidence interval, 1.22 to 1.42; P < 0.001) or graft (relative risk, 1.15; 95% confidence interval, 1.06 to 1.25; P < 0.001) versus an AVF. Every 20% greater case-mix-adjusted catheter use within a facility was associated with 20% greater mortality risk (versus facility AVF use, P < 0.001); and every 20% greater facility graft use was associated with 9% greater mortality risk (P < 0.001). Greater facility catheter and graft use were both associated with greater all-cause and infection-related hospitalization. Catheter and graft use were greater in the United States than in Japan and many European countries. More than half the 36% to 43% greater case-mix-adjusted mortality risk for HD patients in the United States versus the 5 European countries from the DOPPS I and II was attributable to differences in vascular access practice, even after adjusting for other HD practices. Vascular access practice differences accounted for nearly 30% of the greater US mortality compared with Japan.

LIMITATIONS

Possible existence of unmeasured facility- and patient-level confounders that could impact the relationship of vascular access use with outcomes.

CONCLUSIONS

Facility-based analyses diminish treatment-by-indication bias and suggest that less catheter and graft use improves patient survival.

[Hemoglobin variability in chronic renal failure patients]

In recent years, the question of hemoglobin (Hb) stability in patients with chronic renal failure has attracted the interest of medical experts. One of the most important reasons behind this interest is that maintaining the hemoglobin level within the new narrower target range is highly challenging in clinical practice. According to the results available from observational trials, instability of inter-patient hemoglobin levels may be associated with increased morbidity and mortality. To clarify the questions and answers related to this topic and to prepare an updated summary, we reviewed the scientific literature. With the help of the PubMed portal, the incidence, clinical importance, and reasons of Hb variability were summarized according to the available scientific literature. Hb variability is affected by multiple factors which are connected to the general condition of the patient as well as medical interventions and treatments. Also the fluctuation of serum Hb level is a physiological process and is a healthy sign of the capability of the normal human body to adapt. The characteristics and extent of Hb variability vary in patients with chronic renal failure and this topic requires further clinical research. More precise studies are needed in order to explore the differences in possible Hb variability as well as the change in variability caused by particular treatment methods. Finally, based on the available data, the results of future research, and on board scientific consensus, in a strategy for treatment of renal anemia, we should take into account the questions related to Hb stability and variability.

Impact of elevated C-reactive protein levels on erythropoiesis- stimulating agent (ESA) dose and responsiveness in hemodialysis patients

BACKGROUND

Inflammation in an ESRD patient may impact responsiveness to erythropoiesis-stimulating agent (ESA) therapy. We sought to investigate the association between C-reactive protein (CRP) levels and average per-administration epoetin alfa (EPO) dose over 3 months following a CRP measurement.

METHODS

The study is a retrospective cohort study of hemodialysis patients >or=18 years of age receiving care at a Fresenius Medical Care-North America facility between 1 July 2000 and 30 June 2002 who had no history of peritoneal dialysis. All patients had >or=1 CRP measurement and >or=3 months of recorded information before the CRP measurement (entry period). We evaluated the association between CRP levels and average hemoglobin (Hb) and per-administration EPO dose over the 3 months following the CRP measurement.

RESULTS

We identified 1754 patients with a CRP measurement; mean age was 62.6 years (SD 14.1), 51.5% were male, 56.2% were white and the median CRP value was 2.04 mg/dL (20.4 mg/L). Patients in the upper CRP quartiles were more likely to be older, recently hospitalized; have a catheter vascular access; have lower albumin, Hb and transferrin saturation levels and greater EPO doses. In the subsequent 3 months, EPO doses but not Hb levels were significantly higher for patients in the highest CRP quartile [3.21 mg/dL (32.1 mg/L)] (P = 0.01).

CONCLUSIONS

Inflammation as measured by an elevated CRP level appears to be an independent predictor of greater ESA dose requirements. Patients with the highest CRP levels required significantly higher ESA doses to achieve comparable Hb levels even after controlling for potential confounding variables.

Catheter-related mortality among ESRD patients

Hemodialysis access-related complications remain one of the most important sources of morbidity and cost among persons with end-stage renal disease, with total annual costs exceeding $1 billion annually. In this context, the creation and maintenance of an effective hemodialysis vascular access is essential for safe and adequate hemodialysis therapy. Multiple reports have documented the type of vascular access used for dialysis and associated risk of infection and mortality. Undoubtedly, the central venous catheter (CVC) is associated with the greatest risk of infection-related and all-cause mortality compared with the autogenous arteriovenous fistula (AVF) or synthetic graft (AVG). The AVF has the lowest risk of infection, longer patency rates, greater quality of life, and lower all-cause mortality compared with the AVG or CVC. It is for these reasons that the National Kidney Foundation's Kidney Disease Outcome Quality Initiative Clinical Practice Guidelines for Vascular Access recommend the early placement and use of the AVF among at least 50% of incident hemodialysis patients. This report presents catheter-related mortality and calls for heightened awareness of catheter-related complications.

Vascular access-related infections: definitions, incidence rates, and risk factors

Hemodialysis is associated with a high risk of morbidity and mortality, often caused by infections. Infections account for approximately 15% of all deaths in this patient population (the second leading cause after cardiovascular events) and for about one-fifth of admissions. Approximately one-fourth of infection-related admissions are caused by dialysis-associated peritonitis or vascular access infection that may lead to such significant complications as endocarditis or death. Published studies that assessed the determinants of hemodialysis-related vascular infections reported inconsistent findings. Variations in the definitions of infection among these studies despite the existence of standard guidelines proposed by at least 3 major work groups may explain, at least in part, these inconsistencies. A comprehensive in-depth review of those studies is needed to examine the inconsistencies in the published results. We first revised the existing vascular access-related infection definitions, then conducted a narrative review of the published literature that examined predictors of vascular access-related infections, highlighting the heterogeneity in methods and findings. Better understanding of the risk factors for vascular access-related infections may inform efficacious prevention strategies and lead to early detection of infections and improved patient care.

Predictors of central venous catheter use at the initiation of hemodialysis

Central venous catheter (CVC) use at hemodialysis (HD) initiation remains high, despite reports of CVC-associated morbidity and mortality, and efforts at early arteriovenous fistula placement. In order to determine predictors of CVC use at the start of HD, data from the end-stage renal disease (ESRD) Clinical Performance Measures (CPM) Project was linked to the Centers for Medicare & Medicaid Services Medical Evidence (2728) Form. Of the 4071 incident hemodialysis patients in study years 1999-2003, 71.6% used a CVC at dialysis initiation. After controlling for demographic and co-morbid variables, patients with a CVC were 24% more likely to be female (p = 0.006), and 38% more likely to have ischemic heart disease (p = 0.002), while those with obesity (BMI > or = 30) were 24% less likely to start dialysis with a CVC (p = 0.006). Pre-ESRD hypoalbuminemia (< 3.5 g/dl) was associated with a twofold higher risk of CVC use (p = < 0.001), while patients with pre-ESRD anemia (hgb < 11 g/dl) were 29% more likely to use a CVC at dialysis initiation (p = 0.006) compared to those with hemoglobin > or = 11 g/dl. Patients receiving predialysis erythropoietin had a 41% lower odds of CVC use at dialysis initiation (p = < 0.001). Finally, dialysis year was predictive of CVC use; in 2002, 76% of patients initiated dialysis with a CVC compared with 66% in 1998 (p < 0.001). Overall, female gender, ischemic heart disease, lack of obesity, factors suggesting poor pre-ESRD care, and successive year of dialysis initiation were predictive of CVC use at hemodialysis initiation.

Influence of vascular access type on outcome measures in patients on maintenance hemodialysis

BACKGROUND

Previous studies postulate that end-stage renal disease (ESRD) patients dialyzed with central venous catheters (CVC) have poorer outcomes compared to patients using arteriovenous fistulae (AVF) or arteriovenous grafts (AVG). Clinical practice guidelines should obviate these differences if access was not important. This study compared clinical measures of adequacy, anemia, and nutrition/inflammation in prevalent hemodialysis patients in 2003 by access type.

METHODS

Data from The Renal Network Data System were analyzed by univariate analysis of variance to compare Kt/V, URR, albumin, hemoglobin (Hb) and recombinant human erythropoietin (EPO) dose by access type, while adjusting for pertinent factors.

RESULTS

12,501 patients were included. The access type distribution was AVF 36%, AVG 41%, and CVC 23%. CVC patients had lower mean URR, Kt/V, albumin concentration (p < 0.001) than other accesses. Serum Hbs were similar (p = 0.416), however EPO dose (U/kg/week) was higher in those dialyzed with CVC compared to AVF/AVG (p < 0.001).

CONCLUSIONS

Despite practice guidelines, patients dialyzed via CVC have poorer outcome measures compared to other accesses. This suggests that AVF should be used and/or appropriate adjustments need to be made for those dialyzed with CVC to achieve equal outcomes. Further studies defining barriers need to be conducted.

Exploring relative mortality and epoetin alfa dose among hemodialysis patients

BACKGROUND

Confounding-by-indication is a bias in nonexperimental studies that occurs when outcomes are compared for treated and untreated patients and the treatment or medication dose is related to predictors of the outcome. Two recent publications reported that greater epoetin alfa (EPO) doses were associated with increased mortality rates. We assessed whether confounding-by-indication might account for these results.

STUDY DESIGN

We used a retrospective cohort study design.

SETTING & PARTICIPANTS

Hemodialysis patients were randomly selected from a large dialysis organization from July 2000 to June 2002 and were required to have completed a 9-month baseline period.

PREDICTOR

EPO dose assessed during months 7 to 9 of the baseline period and monthly throughout the follow-up period. Hemoglobin (Hb) was assessed as average value during months 4 to 6 of the baseline period and monthly throughout the follow-up period. All other covariates were assessed during months 1 to 6 of the baseline period.

OUTCOME

All-cause mortality during the 1 year of follow-up. Baseline Cox models were fitted with log EPO and Hb with and without adjustment for baseline patient characteristics. Time-dependent models were fitted with time-varying log EPO and Hb and, separately, lagged log EPO and Hb, with adjustment for baseline patient characteristics.

RESULTS

22,955 patients met our inclusion criteria. In the unadjusted model, we observed increased mortality risk with increasing EPO dose (hazard ratio [HR], 1.31 per log unit increase; 95% confidence interval [CI], 1.26 to 1.36). Adjustment for baseline patient characteristics resulted in an appreciably decreased HR (HR, 1.21; 95% CI, 1.15 to 1.28). In the lagged time-dependent analyses, estimates ranged from HR of 0.93 (95% CI, 0.92 to 0.95) to HR of 1.01 (95% CI, 0.99 to 1.03) for the 1- and 2-month lagged models, respectively.

LIMITATIONS

This analysis was limited to prevalent hemodialysis patients, and inhospital EPO dosing information was unavailable.

CONCLUSIONS

The observed mortality risk estimates associated with EPO dose in nonexperimental studies in dialysis patients may be highly sensitive to the analytic method used. This highlights the complexity of evaluating the association between EPO dose, Hb level, and mortality in these studies.

Erythropoiesis-stimulating agent hyporesponsiveness

Approximately 5-10% of patients with chronic kidney disease demonstrate hyporesponsiveness to erythropoiesis-stimulating agents (ESA), defined as a continued need for greater than 300 IU/kg per week erythropoietin or 1.5 mug/kg per week darbepoetin administered by the subcutaneous route. Such hyporesponsiveness contributes significantly to morbidity, mortality and health-care economic burden in chronic kidney disease and represents an important diagnostic and management challenge. The commonest causes of ESA resistance are non-compliance, absolute or functional iron deficiency and inflammation. It is widely accepted that maintaining adequate iron stores, ideally by administering iron parenterally, is the most important strategy for reducing the requirements for, and enhancing the efficacy of ESA. There have been recent epidemiologic studies linking parenteral iron therapy to an increased risk of infection and atherosclerosis, although other investigations have refuted this. Inflammatory ESA hyporesponsiveness has been reported to be improved by a number of interventions, including the use of biocompatible membranes, ultrapure dialysate, transplant nephrectomy, ascorbic acid therapy, vitamin E supplementation, statins and oxpentifylline administration. Other variably well-established causes of ESA hyporesponsiveness include inadequate dialysis, hyperparathyroidism, nutrient deficiencies (vitamin B12, folate, vitamin C, carnitine), angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aluminium overload, antibody-mediated pure red cell aplasia, primary bone marrow disorders, myelosuppressive agents, haemoglobinopathies, haemolysis and hypersplenism. This paper reviews the causes of ESA hyporesponsiveness and the clinical evidence for proposed therapeutic interventions. A practical algorithm for approaching the investigation and management of patients with ESA hyporesponsiveness is also provided.

Association of initial hemodialysis vascular access with patient-reported health status and quality of life

BACKGROUND

Although the arteriovenous fistula (AVF) is the recommended form of vascular access for patients with ESRD, its impact on patient perception of health status, quality of life (QOL), or satisfaction is unknown.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

This study compared patient-reported health status and QOL scores and vascular access type among a national random sample of 1563 patients at dialysis initiation and day 60 of ESRD during 1996 to 1997. Patients were stratified into five categories: AVF at first dialysis and day 60 of ESRD, arteriovenous graft (AVG) at first dialysis and day 60, central venous catheter (CVC) at first dialysis and AVF at day 60, CVC at first dialysis and AVG at day 60, and CVC at first dialysis and day 60.

RESULTS

Ten percent (n = 154) of patients had an AVF, 21% (n = 326) had an AVG, and 69% (n = 1083) had a CVC at dialysis initiation; those who were most likely to use an AVF were white and male. After statistical adjustment, patients with persistent AVF use reported greater physical activity and energy, better emotional and social well-being, fewer symptoms, less effect of dialysis and burden of kidney disease, and better sleep compared with patients with persistent CVC use, whereas measures such as cognitive and sexual function did not differ by access type.

CONCLUSIONS

Compared with persistent CVC use, early persistent AVF use is associated with the perception of improved health status and QOL among patients with ESRD. Future longitudinal studies may help to clarify further the association between QOL and vascular access.

Central venous catheter-related bacteremia in chronic hemodialysis patients: epidemiology and evidence-based management

Central venous catheter-related blood stream infection (CRBSI) is a major cause of morbidity and mortality in patients with end-stage renal disease treated with chronic hemodialysis. Risk factors include Staphylococcus aureus nasal colonization, longer duration of catheter use, previous bacteremia, older age, higher total intravenous iron dose, lower hemoglobin and serum albumin levels, diabetes mellitus and recent hospitalization. Symptoms that raise clinical suspicion of bacteremia in chronic hemodialysis patients are fevers and chills. When CRBSI is suspected, blood cultures should be obtained and empirical therapy with broad spectrum intravenous antibiotics initiated. The diagnosis of CRBSI is confirmed by isolation of the same microorganism from quantitative cultures of both the catheter and the peripheral blood of a patient that has clinical features of infection without any other apparent source. Gram-positive cocci, predominantly S. epidermidis and S. aureus, cause bacteremia in two-thirds of cases. Among the various approaches to management of CRBSI, removal and delayed replacement of the catheter, catheter exchange over a guidewire in selected patients, and the use of antimicrobial/citrate lock solutions have all been found to be promising for treatment and/or prevention; however, resolution of issues regarding selection, dose, duration and emergence of antibiotic-resistant organisms with chronic use of antibiotic lock solutions, as well as the safety of long-term use of trisodium citrate lock solutions, await further randomized, multicenter trials involving larger samples of hemodialysis patients.

Biofilm: its relevance in kidney disease

Biofilm/bioslime is a complex, dynamically interactive multicellular community protected within a heterogeneous exopolysaccharide matrix. Its formation results in the genesis or perpetuation of infection, enhancement of inflammation, and tissue damage or death. Industrial financial losses result from biofilm/bioslime formation; however, the consequences in the medical realm are equally devastating. The relation of biofilm to patients with chronic kidney disease is often covert and extends beyond the colonization of hemodialysis circuits and vascular accesses. Urinary tract device- and vascular access-related biofilms may also increase the burden of cardiovascular risk borne by chronic kidney disease patients, synergizing with the chronic inflammatory state already incurred by these individuals. Current anti-infective strategies are aimed at rapidly killing planktonic forms of microorganisms without specifically targeting the sessile forms that perpetuate their planktonic brethren. Future treatments of infections must ultimately target these reservoirs of infection aiming for their complete eradication. Presently, included among these novel weapons of microdestruction are molecular blockading techniques, electrical enhancement of anti-infectives, and bacterial interference. Nonetheless, the best approach against biofilm formation remains the prevention of microbial colonization, which can be largely by sterile handling of patient-related devices, the most well-established biofilm reservoirs.

Factors Influencing Route of Administration for Epoetin Treatment Among Hemodialysis Patients in the United States

BACKGROUND

Published clinical guidelines advocate subcutaneous (SC) administration for epoetin therapy, although this is practiced among only 7% of all hemodialysis patients. Despite this disparity, few studies have examined factors associated with route of epoetin administration in hemodialysis patients.

METHODS

Data from the Centers for Medicare & Medicaid Services End-Stage Renal Disease Clinical Performance Measures Project were used to identify 13,854 patients receiving hemodialysis in 3,069 dialysis facilities from October to December in 1999 and 2000. Unadjusted associations were examined by using t-test and chi-square test. Adjusted associations were estimated by using generalized estimating equations to control for clustering of patients within the same dialysis facility.

RESULTS

In the United States, use of the SC route of epoetin administration varies widely across the country. After adjusting for patient sociodemographics and comorbidities, the greatest rates of SC therapy are found in the Midwest and West, in providers not affiliated with chains, and in hospital-based and not-for-profit freestanding units. Previous exposure to SC administration (as a predialysis or peritoneal dialysis patient) predicted subsequent SC use, for-profit and large chains were significantly less likely to use SC administration, and increased use of injectable drugs overall (to maximize income) was associated with less SC use.

CONCLUSION

In addition to regional variation in SC use, study findings indicate that physician decision making for epoetin administration route is influenced primarily by type of ownership and financial incentives. Adherence to published clinical guidelines was not a consistent predictor of SC use. Given the similar effectiveness, but significantly decreased dose associated with SC epoetin, these findings suggest an enormous opportunity for cost savings for the Medicare program.

Hemoglobin cycling in hemodialysis patients treated with recombinant human erythropoietin

BACKGROUND

Treatment with recombinant human erythropoietin (rHuEPO) has been a major advance for the management of anemia in patients on hemodialysis. Therapy, however, is often observed to be associated with recurrent cyclic fluctuations in hemoglobin levels. The purpose of this analysis was to describe the phenomenology of hemoglobin cycling during rHuEPO treatment.

METHODS

Data were analyzed for 281 hemodialysis patients treated at Winthrop-University Hospital Dialysis Centers between 1998 and 2003. Eligible patients' first full 1-year period with less than 10 hospital days was studied. Hemoglobin cycling (cycles with amplitude >1.5 g/dL and duration >8 weeks) and excursions (half of one full cycle) were analyzed.

RESULTS

Greater than 90% of patients experienced hemoglobin cycling. The mean number of hemoglobin excursions was 3.1 +/- 1.1 per patient/year. The mean amplitude per hemoglobin excursion was 2.51 +/- 0.89 g/dL. The mean duration of hemoglobin excursions was 10.3 +/- 5.1 weeks. Factors associated with initiation of up excursions included increases in rHuEPO dose (84%), intravenous iron treatment initiation or increase in dose (27%), posthospital discharge (36%), factors associated with down excursions included rHuEPO dose hold (15%) or dose reduction (62%), infection (6%), discontinuation of intravenous iron therapy (5%), and hospitalization (14%). Patients with frequent hemoglobin cycling (>two full cycles per year) were characterized as being more responsive to rHuEPO [index of EPO responsiveness (ERI) 1036 +/- 659 compared to 1992 +/- 701 for other patients] (P = 0.02).

CONCLUSION

Hemoglobin cycling is a common occurrence in rHuEPO-treated hemodialysis patients. It is most closely associated with frequent rHuEPO dose changes, hospitalization, and iron treatment practices.