Associations between changes in hemoglobin and administered erythropoiesis-stimulating agent and survival in hemodialysis patients

Iron therapy in chronic kidney disease: current controversies

Anaemia in chronic kidney disease (CKD) is a complex disease that requires an integrated approach to incorporate both diagnostic and therapeutic interventions and to address the different facets of its aetiology and pathophysiology. The advent of erythropoiesis stimulating agents (ESA) has revolutionised the therapy of anaemia of CKD, and has resulted in a significant decline in the need for blood transfusions in CKD patients. The routine application of ESA has also led to the need for concomitant iron supplementation. ESA and iron therapy now form the cornerstone of anaemia management in CKD. Intravenous iron administration is effective with acceptable safety, and may improve ESA responsiveness. However, less is known about the long-term safety of iron supplementation in CKD patients. Whereas maintenance (weekly to monthly) intravenous iron has been routinely used in maintenance dialysis patients, iron replacement in patients with non-dialysis-dependent CKD is less well studied, in spite of the much larger number of patients affected. This review discusses iron supplementation in CKD with an emphasis toward controversial issues that continue to pose dilemmas in clinical practice. Concerns related to both the optimal amount of iron supplementation and to the safety of various agents available in clinical practice are presented.

Hemoglobin and hematocrit at the end of hemodialysis: a better way to adjust erythropoietin dose?

A severe disadvantage of administration of recombinant human erythropoietin to hemodialysis patients has been reported. A significant correlation has been shown with hemoglobin values determined online by use of the blood volume monitor (BVM) and by laboratory measurement. Online hemoglobin and hematocrit were measured by use of the BVM during hemodialysis session. Data were analyzed by t test and statistical significance was defined as a P of <0.05. Increases in the mean values of hemoglobin and hematocrit from 11.6 +/- 1.9 to 13.9 +/- 2.4 g/dL (17.4 +/- 7.1%, P = 0.02) and from 34.4 +/- 6.8 to 42 +/- 8.3% (20.6 +/- 8.8%, P = 0.022), respectively, were observed from the beginning to the end of dialysis. We hypothesize that a new strategy for adjusting erythropoietin dose may be based on hemoglobin and hematocrit values evaluated at the end of hemodialysis, when patients are no longer hypervolemic. Inadvertent high levels of hemoglobin could be one explanation why patients present higher rates of cardiovascular and access-related events, especially when monitored online by use of the BVM to achieve the dry weight.

Endogenous Erythropoietin and Outcome in Heart Failure

Background— Endogenous erythropoietin is increased in patients with heart failure (HF). Previous small-scale data suggest that these erythropoietin levels are related to prognosis. This study aims to analyze the clinical and prognostic value of erythropoietin levels in relation to hemoglobin in a large cohort of HF patients.

Methods and Results— In patients hospitalized for HF, endogenous erythropoietin levels were measured at discharge and after 6 months. In anemic patients, the relation between erythropoietin and hemoglobin levels was determined by calculating the observed/predicted ratio of erythropoietin levels. We studied data from 605 patients with HF. Mean age was 71±11 years; 62% were male; and mean left ventricular ejection fraction was 0.33±0.14. Median erythropoietin levels were 9.6 U/L at baseline and 10.5 U/L at 6 months. Higher erythropoietin levels at baseline were independently related to an increased mortality at 18 months (hazard ratio, 2.06; 95% confidence interval, 1.40 to 3.04; P <0.01). In addition, persistently elevated erythropoietin levels (higher than median at baseline and at 6 months) were related to an increased mortality risk (hazard ratio, 2.24; 95% confidence interval, 1.02 to 4.90; P =0.044). The observed/predicted ratio was determined in a subset of anemic patients, 79% of whom had erythropoietin levels lower than expected and 9% had levels higher than expected on the basis of their hemoglobin. Multivariate Cox regression analysis revealed that a higher observed/predicted ratio was related to an increased mortality risk (hazard ratio, 3.52; 95% confidence interval, 1.53 to 8.12; P =0.003).

Conclusions— Erythropoietin levels predict mortality in HF patients, and persistently elevated levels have an independent prognostic value. In anemic HF patients, the majority had a low observed/predicted ratio. However, a higher observed/predicted ratio may be related to an independent increased mortality risk.

Initiation of anaemia management in patients with chronic kidney disease not on dialysis in the Veterans Health Administration

BACKGROUND

Erythropoiesis-stimulating agents (ESAs) are frequently used to treat anaemia of chronic kidney disease (CKD) in the dialysis setting; however, few data are available regarding factors influencing initiation of ESAs and other therapies in non-dialysis patients.

METHODS

A retrospective cohort study of Veterans Health Administration data from 2003 to 2005 for 89 585 patients identified as having CKD and anaemia based on two outpatient estimated glomerular filtration rates <60 ml/min/1.73 m(2) and at least one outpatient haemoglobin (Hb) <11 g/dL. Hb levels, patient demographics, clinical and provider characteristics and procedures predicted ESA treatment initiation over 1 year of follow-up. Multivariable logistic and pooled logistic survival models identified predictors of ESA initiation.

RESULTS

Overall, 6381 subjects (7.1%) initiated ESAs within 1 year of the index Hb; initiation was more common (8.6%) for patients with Hb <10 g/dL. Iron therapy use varied by initial Hb levels (27.6% to 52.4%) as did transfusions (12.5% to 42.8%); each was more common at lower Hb levels. Hbs rose to above 11 g/dL for 25-50% of patients in the absence of any treatment or by transfusion/iron therapy. Factors predicting time to ESA initiation included: nephrologist [odds ratio (OR = 2.3)] or haematologist care (OR = 2.2) and iron therapy (OR = 1.6). Transfusions increased for patients with increasing follow-up time.

CONCLUSION

Iron therapy is more common than ESA treatment in patients with CKD and Hbs <11 g/dL in the VA. Correction of anaemia in the absence of any ESA treatment was common at higher Hbs levels, but much less so when Hb levels fell below 10 g/dL.

Association of hemodialysis treatment time and dose with mortality and the role of race and sex

BACKGROUND

The association of survival with characteristics of thrice-weekly hemodialysis (HD) treatment, including dose or duration of treatment, has not been completely elucidated, especially in different race and sex categories.

STUDY DESIGN

We examined associations of time-averaged and quarterly varying (time-dependent) delivered HD dose and treatment time and 5-year (July 2001-June 2006) survival.

SETTING & PARTICIPANTS

88,153 thrice-weekly-treated HD patients from DaVita dialysis clinics.

PREDICTORS

HD treatment dose (single-pool Kt/V) and treatment time.

OUTCOMES & OTHER MEASUREMENTS

5-Year mortality.

RESULTS

Thrice-weekly treatment time < 3 hours (but > or = 2.5 hours) per HD session compared with > or = 3.5 hours (but < 5 hours) was associated with increased death risk independent of Kt/V dose. The greatest survival gain of higher HD dose was associated with a Kt/V approaching the 1.6-1.8 range, beyond which survival gain was minimal, nonexistent, or even tended to reverse in African American men and those with 4-5 hours of HD treatment. In non-Hispanic white women, Kt/V > 1.8 continued to show survival advantage trends, especially in time-dependent models.

LIMITATIONS

Our results may incorporate uncontrolled confounding. Achieved Kt/V may have different associations than targeted Kt/V.

CONCLUSIONS

HD treatment dose and time appear to have different associations with survival in different sex or race groups. Randomized controlled trials may be warranted to examine these associations across different racial and demographic groups.

Considering health insurance: how do dialysis initiates with Medicaid coverage differ from persons without Medicaid coverage?

BACKGROUND

Type of health insurance is an important mediator of medical outcomes in the United States. Medicaid, a jointly sponsored Federal/State programme, is designed to serve medically needy individuals. How these patients differ from non-Medicaid-enrolled incident dialysis patients and how these differences have changed over time have not been systematically examined.

METHODS

Using data from the United States Renal Data System, we identified individuals initiating dialysis from 1995 to 2004 and categorized their health insurance status. Longitudinal trends in demographic, risk behaviour, functional, comorbidity, laboratory and dialysis modality factors, as reported on the Medical Evidence Form (CMS-2728), were examined in all insurance groups. Polychotomous logistic regression was used to estimate adjusted generalized ratios (AGRs) for these factors by insurance status, with Medicaid as the referent insurance group.

RESULTS

Overall, males constitute a growing percentage of both Medicaid and non-Medicaid patients, but in contrast to other insurance groups, Medicaid has a higher proportion of females. Non-Caucasians also constitute a higher proportion of Medicaid patients than non-Medicaid patients. Body mass index increased in all groups over time, and all groups witnessed a significant decrease in initiation on peritoneal dialysis. Polychotomous regression showed generally lower AGRs for minorities, risk behaviours and functional status, and higher AGRs for males, employment and self-care dialysis, for non-Medicaid insurance relative to Medicaid.

CONCLUSIONS

While many broad parallel trends are evident in both Medicaid and non-Medicaid incident dialysis patients, many important differences between these groups exist. These findings could have important implications for policy planners, providers and payers.

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.

Fluctuations in haemoglobin levels in haemodialysis, pre-dialysis and peritoneal dialysis patients receiving epoetin alpha or darbepoetin alpha

AIM

To characterize the haemoglobin variability of haemodialysis, peritoneal dialysis and pre-dialysis patients treated with either epoetin alpha or darbepoetin alpha in a clinical setting where treatment was administered according to current standard Australian practice.

METHODS

Data on haemodialysis, pre-dialysis and peritoneal dialysis patients were extracted from the Renal Anaemia Management database (RAM) from 1 January 2001 to 31 December 2004. The variance in haemoglobin was calculated from patient records with more than five haemoglobin observations over a period of at least 4 weeks following 9 weeks of therapy. A mixed-model was fitted to the within-patient variances and weighting was based on the number of observations minus 1 for each record.

RESULTS

The mean within-patient variance in haemoglobin levels for i.v. administered erythropoietin-stimulating agents (IV) haemodialysis, s.c. administered erythropoietin-stimulating agents (SC) haemodialysis, predialysis (SC) and peritoneal dialysis (SC) patients receiving epoetin alpha were 9% (95% CI: 13% to 5%, P < 0.0001), 17% (95% CI: 32% to 0.2%, P = 0.047), 19% (95% CI: 27% to 11%, P < 0.0001) and 26% (95% CI: 33% to 18%, P < 0.0001) lower than that for patients receiving darbepoetin alpha. The mean haemoglobin levels for haemodialysis (IV), haemodialysis (sc) predialysis (SC) and peritoneal dialysis (SC) patients receiving darbepoetin alpha were 11.6 g/dL, 11.2 g/dL, 11.5 g/dL and 11.5 g/dL compared with 11.5 g/dL, 11.6 g/dL, 11.7 g/dL and 11.5 g/dL for patients receiving epoetin alpha.

CONCLUSION

There was 9-26% greater within-patient fluctuation in haemoglobin levels in patients receiving darbepoetin alpha compared with epoetin alpha. The causes of haemoglobin fluctuations and the implications for patient outcomes and resource use require further study.

Relative risk of death in UK haemodialysis patients in relation to achieved haemoglobin from 1999 to 2005: an observational study using UK Renal Registry data incorporating 30,040 patient-years of follow-up

BACKGROUND

Much controversy has been generated in recent times over the optimal target haemoglobin in chronic kidney disease patients receiving erythropoiesis-stimulating agent therapy. This has arisen from the paradoxical conclusions obtained from large retrospective or epidemiological studies versus interventional randomized controlled trials.

METHODS

Data from haemodialysis patients in the UK Renal Registry from 1999 to 2005 were analysed year by year for the relative risk of death at different haemoglobin concentrations, compared with a reference of 10-11 g/dl. The population size varied from 2291 in 1999 to 8209 in 2005. The data were analysed by chi-square tests, and a multivariate analysis was performed.

RESULTS

Across the years 1999 to 2005, there was a consistent relationship between the haemoglobin achieved and the risk of death (P < 0.0001). In 2005, the relative risk (RR) of death = 1.32 for a haemoglobin (Hb) of 9-10 g/dl; RR = 0.44 for Hb > 13 g/dl. The relationship between Hb and the RR of death is nevertheless remarkably consistent across the 7 years of study, with an S-shaped correlation (polynomial) between an Hb range of <9 g/dl and an Hb range of >13 g/dl (P < 0.0001). Multivariate analysis also showed age, time on dialysis and diabetes to be strongly predictive of death across all 7 years analysed (P < 0.0001 in all cases).

CONCLUSION

There is a significant relationship between achieved haemoglobin and mortality across the 7 years analysed, with no increase in risk seen with higher Hb levels.

Anemia in renal disease: diagnosis and management

Chronic kidney disease (CKD) is a widespread health problem in the world and anemia is a common complication. Anemia conveys significant risk for cardiovascular disease, faster progression of renal failure and decreased quality of life. Patients with CKD can have anemia for many reasons, including but not invariably their renal insufficiency. These patients require a thorough evaluation to identify and correct causes of anemia other than erythropoietin deficiency. The mainstay of treatment of anemia secondary to CKD has become erythropoiesis-stimulating agents (ESAs). The use of ESAs does carry risks and these agents need to be used judiciously. Iron deficiency often co-exists in this population and must be evaluated and treated. Correction of iron deficiency can improve anemia and reduce ESA requirements. Partial, but not complete, correction of anemia is associated with improved outcomes in patients with CKD.

CMV seropositivity determines epoetin dose and hemoglobin levels in patients with CKD

Cytomegalovirus (CMV)-seropositive patients with ESRD may have more CD4(+) T cells lacking the co-stimulatory molecule CD28 (CD4(+)CD28null) than CMV-seronegative patients. Increased numbers of CD28null T cells associates with epoetin nonresponsiveness in patients with ESRD, but whether expansion of CD4+CD28null T cells in CMV-seropositive patients associates with demand for epoetin is unknown. In a cohort of 129 stable patients with ESRD, CMV seropositivity significantly associated with a lower hemoglobin level in predialysis patients (12.5 versus 11.5 g/dl; P < 0.02). CMV seropositivity did not associate with average hemoglobin level in hemodialysis patients, but CMV-seropositive patients required significantly more epoetin (median 12,000 versus 6300 U/wk; P = 0.02). Multivariate linear regression analysis identified CMV seropositivity as the only variable significantly associated with hemoglobin levels in predialysis patients and epoetin dosages in hemodialysis patients. In CMV-seropositive hemodialysis patients, the number of circulating CD4(+)CD28null T cells positively correlated with epoetin dosage. These CD4(+)CD28null T cells were proinflammatory; they were capable of producing large amounts of IFN-gamma and TNF-alpha. In conclusion, expansion of CD4(+)CD28null T cells in CMV-seropositive patients with ESRD associates with increased demand for epoetin.

Iron-refractory iron deficiency anemia: new molecular mechanisms

Iron deficiency anemia is a common complication in end-stage renal disease (ESRD) and impairs the therapeutic efficacy of recombinant erythropoietin. Oral or parental iron supplements usually are effective in treating iron deficiency anemia. Some patients, however, respond poorly to iron supplements and are diagnosed as having iron-refractory iron deficiency anemia. The condition exacerbates ESRD but its underlying mechanism was unclear. Hepcidin is a central player in iron homeostasis. It downregulates the iron exporter ferroportin, thereby inhibiting iron absorption, release, and recycling. In ESRD, plasma hepcidin levels are elevated, which contributes to iron deficiency in patients. Matriptase-2, a liver transmembrane serine protease, has been found to have a major role in controlling hepcidin gene expression. In mice, defects in the Tmprss6 gene encoding matriptase-2 result in high hepcidin expression and cause severe microcytic anemia. Similarly, mutations in the human TMPRSS6 gene have been identified in patients with iron-refractory iron deficiency. Thus, matriptase-2 is critical for iron homeostasis and may have an important role in ESRD.

Anemia management and association of race with mortality and hospitalization in a large not-for-profit dialysis organization

BACKGROUND

The optimal hemoglobin target and possible toxicity of epoetin therapy in hemodialysis patients are controversial. Previous studies suggest that African American patients use higher doses of epoetin and have better survival compared with white hemodialysis patients.

STUDY DESIGN

Retrospective longitudinal cohort.

SETTING & PARTICIPANTS

Epoetin-exposed incident hemodialysis patients (N = 12,733; African Americans, n = 4,801; white, n = 7,386) treated in Dialysis Clinic Inc facilities during 2000 to 2006.

PREDICTORS

Hemoglobin, epoetin, iron.

OUTCOMES

Mortality, hospitalization.

MEASUREMENTS

Proportional hazards models with time-varying covariates.

RESULTS

Hemoglobin concentrations less than 10 g/dL in whites and less than 11 g/dL in African Americans were associated with increased mortality and hospitalization versus the referent hemoglobin level of 11 to 11.9 g/dL. Hemoglobin levels of 13 g/dL or greater in whites were associated with decreased noncardiovascular mortality. Six-month cumulative epoetin doses of 20,000 U/wk or greater were associated with increased mortality and hospitalization versus the referent group (8,000 to 12,499 U/wk). Epoetin doses less than 8,000 U/wk were associated with decreased risk. Higher epoetin doses were associated with increased mortality at hemoglobin concentrations of 10 to 12.9 g/dL and with increased hospitalization at all hemoglobin concentrations of 10 g/dL or greater. Higher epoetin doses were associated with increased mortality and hospitalization within each tertile of serum albumin concentration. These patterns did not differ by race.

LIMITATIONS

Treatment-by-indication bias and unidentified confounders cannot be excluded. Small sample sizes in the highest and lowest hemoglobin strata decrease statistical power.

CONCLUSIONS

Relationships between hemoglobin concentration and mortality differed between African Americans and whites. Additionally, the relationship of lower mortality with greater achieved hemoglobin concentration seen in white patients was observed for all-cause, but not cardiovascular, mortality. A higher cumulative epoetin dose was associated with worse outcomes, even in patients with albumin levels greater than 4 g/dL. There were no statistically significant interactions between race and epoetin dose. Further studies are needed to confirm and to define the mechanism of these findings.

Posttransplant anemia: the role of sirolimus

Posttransplant anemia is a common problem that may hinder patients' quality of life. It occurs in 12 to 76% of patients, and is most common in the immediate posttransplant period. A variety of factors have been identified that increase the risk of posttransplant anemia, of which the level of renal function is most important. Sirolimus, a mammalian target of rapamycin inhibitor, has been implicated as playing a special role in posttransplant anemia. This review considers anemia associated with sirolimus, including its presentation, mechanisms, and management.

Drug safety profile of darbepoetin alfa for anemia of chronic kidney disease

Anemia of chronic kidney disease due to deficiency of erythropoietin is common and has clinical consequences. Erythropoiesis stimulating agents including darbepoetin alfa (DA) are effective in correcting anemia. DA is generally well tolerated and has side effect profile similar to recombinant human erythropoietin. It has a long half-life permitting infrequent dosing. DA has been tested extensively in preclinical and clinical studies and significant experience has accumulated in clinical practice. Global safety profile of DA must consider recent data indicating worse survival, poor cardiovascular outcomes and thrombotic risks of targeting near normal hemoglobin levels and administering high doses of erythropoiesis stimulating agents. Strategies to achieve and maintain a reasonable, individualized target hemoglobin level with minimal variations in hemoglobin level are needed.

Review article: Biomarkers of clinical outcomes in advanced chronic kidney disease

Chronic kidney disease (CKD) is a complex condition, where the decrease in kidney function is accompanied by numerous metabolic changes affecting virtually all the organ systems of the human body. Many of the biomarkers characteristic of the individually affected organ systems have been associated with adverse outcomes including higher mortality in advanced CKD, whereas in persons without CKD these biomarkers may have no bearing on survival. It is believed that the high mortality seen in CKD is a result of several abnormalities conspiring to induce or aggravate a heightened degree of cardiovascular morbidity and predisposition to wasting syndrome. Not all the biomarkers may, however, be causally responsible for the adverse outcomes associated with them. We review various biomarkers of protein-energy wasting, inflammation, oxidative stress, potassium disarrays, acid-base disorders, bone and mineral disorders, glycemic status, and anemia. Although all of these biomarkers have shown associations with worsened outcomes in CKD, markers of protein-energy wasting, especially serum albumin, remain the strongest predictor of survival in CKD patients, especially those undergoing maintenance dialysis treatment. We also review the putative pathophysiologic mechanisms behind these associations, and present potential therapeutic interventions that could result in remedies to improve poor clinical outcomes in CKD, pending the results of current and future controlled trials.

Hemoglobin variability in nondialysis chronic kidney disease: examining the association with mortality

BACKGROUND AND OBJECTIVES

Anemia and hemoglobin (Hb) variability are associated with mortality in hemodialysis patients who are on erythropoiesis-stimulating agents (ESA). Our aim was to describe the degree of Hb variability present in nondialysis patients with chronic kidney disease (CKD), including those who were not receiving ESA, and to investigate the association between Hb variability and mortality.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Hb variability was determined using 6 mo of "baseline" data between January 1, 2003, and October 31, 2005. A variety of definitions for Hb variability were examined to ensure consistency and robustness.

RESULTS

A total of 6165 patients from 22 centers in seven countries were followed for a mean of 34.0 +/- 15.8 mo; 49% were prescribed an ESA. There was increased Hb variability with ESA use; the residual SD of Hb was 4.9 +/- 4.4 g/L in patients who were not receiving an ESA, compared with 6.8 +/- 4.8 g/L. Hb variability was associated with a small but significantly increased risk for death per g/L residual SD, irrespective of ESA use. Multivariate linear regression model explained only 11% of the total variance of Hb variability.

CONCLUSIONS

Hb variability is increased in patients who have CKD and are receiving ESA and is associated with an increased risk for death (even in those who are not receiving ESAs). This analysis cannot determine whether Hb variability causally affects mortality. Thus, the concept of targeting Hb variability with specific agents needs to be examined within the context of factors that affect both Hb variability and mortality.

Predictors of hyporesponsiveness to erythropoiesis-stimulating agents in hemodialysis patients

BACKGROUND

Identification of predictors of hyporesponsiveness to erythropoietin-stimulating agents (ESAs) in hemodialysis (HD) patients may help improve anemia management and reduce hemoglobin level variability.

STUDY DESIGN

We conducted repeated-measure and logistic regression analyses in a retrospective cohort of long-term HD patients to examine the association of iron markers and measures of renal osteodystrophy with ESA responsiveness. The ESA response coefficient at the individual level, ie, the least confounded dose-response association, was separated from the population level, assumed to represent confounding by medical indication.

SETTING/PARTICIPANTS

The national database of a large dialysis organization (DaVita Inc, El Segundo, CA) with 38,328 surviving prevalent HD patients during 12 months who received ESA for at least 3 consecutive calendar quarters was examined.

PREDICTORS

Serum levels of ferritin, iron saturation ratio, intact parathyroid hormone, and alkaline phosphatase. OUTCOMES/OTHER MEASUREMENTS: The main outcome was case-mix-adjusted hemoglobin response to quarterly averaged ESA dose at the individual level. The odds ratio (OR) of the greatest versus poorest ESA-response quartile at the patient level was calculated. OR less than 1.0 indicated ESA hyporesponsiveness, and OR greater than 1.0, enhanced responsiveness.

RESULTS

Mean ESA-response coefficients of the least to most responsive quartiles were 0.301 +/- 0.033 (SD), 0.344 +/- 0.004, 0.357 +/- 0.004, and 0.389 +/- 0.026 g/dL greater hemoglobin level per 1,000 U/wk greater ESA dose in each quarter, respectively. The ORs of greatest versus poorest ESA responsiveness at the patient level were serum ferritin level less than 200 ng/mL (0.77; 95% confidence interval [CI], 0.70 to 0.86; reference, 200 to 500 ng/mL), iron saturation ratio less than 20% (0.54; 95% CI, 0.49 to 0.59; reference, 20% to 30%), intact parathyroid hormone level of 600 pg/mL or greater (0.54; 95% CI, 0.49 to 0.60; reference, 150 to 300 pg/mL), and alkaline phosphatase level of 160 IU/L or greater (0.64; 95% CI, 0.58 to 0.70; reference, 80 to 120 IU/L). Lower estimated dietary protein intake and serum levels of nutritional markers were also associated with greater risk of ESA hyporesponsiveness.

LIMITATIONS

Our results may incorporate uncontrolled confounding. Achieved hemoglobin level may have different associations than targeted hemoglobin level.

CONCLUSIONS

In long-term HD patients, low iron stores, hyperparathyroidism, and high-turnover bone disease are associated with significant ESA hyporesponsiveness. Prospective studies are needed to verify these associations.

Maintenance of target hemoglobin level in stable hemodialysis patients constitutes a theoretical task: a historical prospective study

Maintenance of target hemoglobin (Hb) values in hemodialysis patients treated with erythropoiesis-stimulating agents (ESAs) remains difficult. We examined Hb variability in the clinical setting in hemodialysis patients. Hemodialysis patients treated with ESAs who maintained the recommended Hb range of 11-13 g per 100 ml over 3 months and were not admitted to hospital, did not require transfusion, and did not experience any major clinical event during this period were followed prospectively for 1 year. Anemia events, Hb variation events (any value out of +/-1.5 g per 100 ml of the median Hb level in the total follow-up period for the individual patient), risk factors for anemia, and Hb variation events were assessed. We studied 420 patients (63% males, mean age 61 years), 222 received short-acting erythropoietin (EPO) and 198 long-acting darbepoetin. A total of 4654 blood samples (mean 11.1 per patient-year) were analyzed. Only 3.8% of patients were maintained within the target Hb levels (11-13 g per 100 ml) during 1 year. Hb variation events occurred in 20.8% of laboratory values and anemia events in 14.7%, with a median time to the first event of 3 months. Treatment with short-acting EPO (vs long-acting darbepoetin), change of ESA dose in the previous visit, resistance index, and hospitalization were significant risk factors for both anemia events and Hb variation events. Our results show that Hb values are rarely maintained within the recommended guidelines even in more stable hemodialysis patients. Hb variability is frequently associated with clinical events or ESA dose changes. Long-acting darbepoetin achieved better Hb stability than short-acting EPO.

Factors that condition the response to erythropoietin in patients on hemodialysis and their relation to mortality

The response to erythropoietin-stimulating agents (ESA) can vary among different patients and according to the different circumstances over time within a given individual. The aim of this study was to analyze the factors that can modify the response to epoetin in patients on hemodialysis (HD) and its influence on early mortality. Prospective and observational study including 1710 patients from 119 HD units in Spain with a follow-up of 12 months. To evaluate the dose-response effect of EPO therapy, we used the erythropoietin resistance index (ERI), calculated as the weekly weight-adjusted dose of EPO divided by the hemoglobin level. Patients were stratified in three groups according to ERI: group A, ERI <5; group B, ERI=5-15; group C, ERI>15 U/kg/week/g per 100 ml. Mean ERI for the entire group was 10.2+/-7.3 U/kg/week/g per 100 ml. ERI was directly related with incident comorbidity (Charlson Index), age, female gender and low body mass index with no relationship with etiology of chronic kidney disease. Patients with antecedents of heart failure, acute infection or malignant neoplasm had significantly higher ERI than those without. Transferrin saturation index, but not serum ferritin, was inversely related with ERI. Serum levels of albumin and cholesterol were related with lower ERI, but no relation was found with normalized protein catabolic rate. Patients with a permanent catheter for HD had significant higher values of ERI than those with native fistula (P=0.012). One year survival in all three groups of patients according to ERI was 0.916 in group A, 0.877 in group B and 0.788 in group C (log-rank=20.7, P<0.001). The resistance to ESA is directly related with incident comorbidity in patients on hemodialysis and it can be interpreted as a useful marker of early mortality.

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.

Managing Anemia of Chronic Kidney Disease

Anemia begins early in the course of declining kidney function and is a frequent complication of chronic kidney disease. Both anemia and chronic kidney disease are underdiagnosed and undertreated. Anemia is associated with significantly increased risk of morbidity and mortality, including increased risks of left ventricular hypertrophy and heart failure. Although the detrimental effects of anemia are more common in patients with advanced chronic kidney disease, it has been suggested that correcting anemia in early stage kidney disease may improve health-related quality of life and also delay the progression to end-stage kidney disease. The identification of anemia in early stage chronic kidney disease and its aggressive management may also improve cardiovascular complications. Anemia of chronic kidney disease is predominantly a result of abnormal erythropoietin production and iron deficiency. Anemia may be the result of kidney failure itself, blood losses, nutritional deficiencies, and endocrine disorders. Guidelines and protocols for treating anemia can assist practitioners in identifying patients with anemia, treating anemia, evaluating response to treatment, and modifying treatment based on response. Erythropoeisis-stimulating agents have been shown to be effective in treating anemia in predialysis and dialysis patients. Iron supplementation is usually required in patients receiving erythropoeisis-stimulating agent therapy or with iron deficiency. Successfully managing anemia of chronic kidney disease with treatment strategies that accommodate patient lifestyle and improve compliance is paramount. Primary care physicians play an important role in the care of patients with kidney disease, as does collaboration with other medical professionals involved in their care.

What is so bad about a hemoglobin level of 12 to 13 g/dL for chronic kidney disease patients anyway?

Randomized controlled trials (RCTs) clearly indicate a possible cardiovascular morbidity and mortality risk when deliberately targeting a normal hemoglobin (Hb) concentration of 13 to 15 g/dL. By contrast, observational studies point to greater hospitalization and mortality at Hb levels <11 g/dL. There are no direct data to help us determine where, within this broad range, the optimal Hb lies. In RCTs and observational studies, significant confounding from the interrelationships of anemia and epoetin resistance occurs in patients with a serious illness. Patients with comorbidities such as malnutrition and inflammatory processes are more resistant to epoetin and, invariably, require greater cumulative epoetin doses. The effect of a higher erythropoiesis-stimulating agent (ESA) dose on increasing mortality has been noted repeatedly in post hoc analyses of RCTs. It is therefore too simplistic to solely attribute the outcomes achieved in RCTs to "target Hb." We discuss various mechanisms for potential harm at higher Hb levels as opposed to those that may be obtained from higher epoetin doses. For the individual patient, the therapeutic decision should center on what Hb is most appropriate at a "safe" ESA dose. Consequently, an Hb of 12 to 13 g/dL may be totally appropriate in some patient populations.

Intravenous iron versus erythropoiesis-stimulating agents: friends or foes in treating chronic kidney disease anemia?

Patients with chronic kidney disease (CKD), especially those requiring maintenance hemodialysis treatments, may lose up to 3 g of iron each year because of frequent blood losses. Higher doses of erythropoiesis-stimulating agents (ESAs) may worsen iron depletion and lead to an increased platelet count (thrombocytosis), ESA hyporesponsiveness, and hemoglobin variability. Hence, ESA therapy requires concurrent iron supplementation. Traditional iron markers such as serum ferritin and transferrin saturation ratio (TSAT) (ie, serum iron divided by total iron-binding capacity [TIBC]), may be confounded by non-iron-related conditions. Whereas serum ferritin <200 ng/mL suggests iron deficiency in CKD patients, ferritin levels between 200 and 1,200 ng/mL may be related to inflammation, latent infections, malignancies, or liver disease. Protein-energy wasting may lower TIBC, leading to a TSAT within the normal range, even when iron deficiency is present. Iron and anemia indices have different mortality predictabilities, in that high serum ferritin but low iron, TIBC, and TSAT levels are associated with increased mortality, whereas hemoglobin exhibits a U-shaped risk for death. The increased mortality associated with targeting hemoglobin above 13 g/dL may result from iron depletion-associated thrombocytosis. Intravenous (IV) iron administration may not only decrease hemoglobin variability and ESA hyporesponsiveness, it may also reduce the greater mortality associated with the much higher ESA doses that have been used in some patients when targeting higher hemoglobin levels.

Hemoglobin variability and hyporesponsiveness: much ado about something or nothing?

Hemoglobin (Hb) variability is considered a discrete clinical entity that when present may presage poor clinical outcomes. However, Hb variability is an intrinsic property of biological systems and is present in all patients, those with and without the anemia of chronic kidney disease. Taken together, variability actually represents the integration of multiple influences at multiple levels in the life of a red cell, namely the summation of positive and negative influences on erythropoiesis. Thus, Hb variability may be interpreted as a mathematic function of time and is the result of a host of influences including definition of the normal Hb range, native erythron responsiveness/hyporesponsiveness, temporal changes in endogenous and exogenous erythropoiesis-stimulating agent (ESA) levels, the algorithms used to dose ESAs and their duration of action, the presence of biologically available iron, red cell turnover, and recyclable and non-recyclable blood loss and gain. When viewed within this construct of matrixed determinants, the source of hemoglobin variability is more readily identified. When variability is present but the etiology is not easily discerned, erythropoietic hyporesponsiveness must be considered and evaluated. Finally, integration of all of these concepts is possible within the context of an anemia management protocol.

Hemoglobin variability in anemia of chronic kidney disease

Hemoglobin levels in individuals with chronic kidney disease fluctuate frequently above or below the recommended target levels within short periods of time even though the calculated mean hemoglobin remains within the target range of 11 to 12 g/dl. Both pharmacologic features and dosing of erythropoiesis-stimulating agents may lead to cyclic pattern of hemoglobin levels within the recommended range. Several longitudinal studies highlight the complexity of maintaining stable hemoglobin levels over time. As a consequence, patients may risk increased hospitalization and mortality, because both low and high hemoglobin levels are associated with increased cardiovascular events and death. The duration of time that hemoglobin remains higher or lower than the target thresholds may be important to adverse outcomes. It is not clear whether adverse effects of hemoglobin variability are because of the therapy with erythropoiesis-stimulating agents and/or iron or despite such a therapy. Several factors affect hemoglobin variability, including those that are drug related, such as pharmacokinetic parameters, patient-related differences in demographic characteristics, and factors affecting clinical status, as well as clinical practice guidelines, treatment protocols, and reimbursement policies. Strategies that consider each of these factors and reduce hemoglobin variability may be associated with improved clinical outcomes.

Association of quarterly average achieved hematocrit with mortality in dialysis patients: a time-dependent comorbidity-adjusted model

BACKGROUND

Recent publications suggest that increased mortality is associated with high hematocrit targets in erythropoietin-stimulating agent-treated patients with chronic kidney disease. We aim to further inform the debate about optimal hematocrit targets, advancing the hypothesis that the current hematocrit target may not optimize the survival of patients with end-stage renal disease.

STUDY DESIGN

Cross-sectional observational study.

SETTING & PARTICIPANTS

Medicare dialysis patients from 2002 to 2004 (n = 393,967).

FACTORS

Quarterly average hematocrit and erythropoietin alfa (EPO) dose.

OUTCOMES

Mortality hazard ratios from time-dependent Cox proportional hazard models, adjusting for comorbidities.

RESULTS

N = 2,712,197 patient-facility quarters. During the study, 100,086 deaths were identified. Percentages of patient quarters within each hematocrit category: hematocrit less than 27% (2.0%), 27% to 28.49% (1.7%), 28.5% to 29.9% (2.9%), 30% to 31.49% (5.2%), 31.5% to 32.99% (9.0%), 33% to 34.49% (14.9%), 34.5% to 35.99% (19.2%), 36% to 37.49% (18.0%), 37.5% to 38.99% (12.0%), 39% to 40.49% (6.4%), 40.5% to 41.99% (3.0%), and 42% or greater (3.1%). Mortality hazard ratios from the fully adjusted model: hematocrit less than 27% (3.11), 27% to 28.49% (2.60), 28.5% to 29.9% (2.14), 30% to 31.49% (1.80), 31.5% to 32.99% (1.44), 33% to 34.49% (1.17), 34.5% to 35.99% (reference), 36% to 37.49% (0.98), 37.5% to 38.99% (1.01), 39% to 40.49% (1.13), 40.5% to 41.99% (1.32), and 42% or greater (1.57).

LIMITATIONS

First, potential confounding by indication related to associations between underlying illness and mortality, anemia, and EPO responsiveness. Second, Medicare claims data reflect a range of conditions and degrees of severity not easily translated into the clinical context. Third, for Medicare claims, EPO reporting is not required if EPO is not billed. Greater than 95% of "missing hematocrit" quarters are "EPO = 0" patient quarters. Interpretation of results for the missing hematocrit and EPO = 0 use categories is complicated by data source limitations.

CONCLUSIONS

We show an association between mortality and low hematocrit in dialysis patients, in part reflecting the presence of comorbidities. We also show an association between increased mortality and high hematocrit. Additional interventional trials should be undertaken to better define the optimal target for anemia management in patients with end-stage renal disease, with careful prospective identification of underlying comorbidities and clinical factors contributing to high erythropoietin-stimulating agent requirement.

Use of darbepoetin alfa in the treatment of anaemia of chronic kidney disease: clinical and pharmacoeconomic considerations

The introduction of erythropoiesis-stimulating agents (ESAs) into everyday clinical practice has greatly improved the care of patients with chronic kidney disease. ESAs have reduced the need for blood transfusions, improved survival, decreased cardiovascular complications and enhanced patient quality of life. The longer acting ESA, darbepoetin alfa (Aranesp®), which can be administered less frequently than traditional ESAs, provides further benefits to both patients and healthcare professionals relative to the epoetins. Clinical studies have shown that darbepoetin alfa administered once every 2 weeks or once every month allows enhanced convenience and cost savings with no compromise in efficacy, while maintaining patients within target haemoglobin ranges.

The controversy surrounding hemoglobin and erythropoiesis-stimulating agents: what should we do now?

Treatment of the anemia of chronic kidney disease (CKD) with erythropoiesis-stimulating agents (ESAs) has been intensely debated during the past 2 years. Treatment with ESAs has transformed the lives of millions of patients with CKD, with fewer blood transfusions and improved quality of life. However, randomized trials have suggested that targeting greater hematocrits/hemoglobin levels and/or exposure to high doses of ESAs is associated with a greater risk of cardiovascular complications and mortality. The US Food and Drug Administration has inserted a boxed warning for ESAs and, along with the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (KDOQI), decreased recommended target hemoglobin ranges for ESA therapy. The Centers for Medicare & Medicaid Services has decreased ESA dosing recommendations in the Medicare claims policy for ESAs. Managing the anemia of CKD in the era of the hemoglobin level and ESA controversy has required aiming for appropriate hemoglobin levels, using the lowest effective ESA dose, and better managing the problem of ESA hyporesponsiveness.

Combined high serum ferritin and low iron saturation in hemodialysis patients: the role of inflammation

BACKGROUND

Serum ferritin, frequently used as a marker of iron status in individuals with chronic kidney disease, is also an inflammatory marker. The concurrent combination of high serum ferritin and low iron saturation ratio (ISAT) usually poses a diagnostic dilemma. We hypothesized that serum ferritin > or =500 ng/ml, especially in the seemingly paradoxical presence of ISAT level <25%, is more strongly associated with inflammation than with iron in maintenance hemodialysis (MHD) patients.

DESIGN, SETTING, AND PARTICIPANTS

In 789 MHD patients in the Los Angeles area, the association of serum ferritin > or =500 ng/ml with inflammatory markers, including IL-6 (IL-6) and C-reactive protein levels, and malnutrition-inflammation score (MIS) was examined.

RESULTS

After multivariate adjustment for case-mix and other measures of malnutrition-inflammation complex, MHD patients with serum ferritin > or =500 ng/ml and ISAT <25% had higher odds ratio for serum C-reactive protein > or =10 mg/L. The area under the receiver operating characteristic curves for the continuum of ISAT and IL-6 in detecting a serum ferritin > or =500 ng/ml were identical (0.57 versus 0.56, P = 0.7). The combination of IL-6 with ISAT yielded a higher area under the receiver operating characteristic curve (0.61) than either ISAT or IL-6 alone (P = 0.03 and P = 0.02, respectively).

CONCLUSION

In MHD patients, ferritin values above 500 ng/ml, especially in paradoxical conjunction with low ISAT, are associated with inflammation. Strategies to dissociate inflammation from iron metabolism to mitigate the confounding impact of inflammation on iron and to improve iron treatment responsiveness may improve anemia management in chronic kidney disease.

[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.

Intravenous versus oral iron supplementation for the treatment of anemia in CKD: systematic review and meta-analysis

BACKGROUND

Iron supplementation is essential for the treatment of patients with anemia of chronic kidney disease (CKD). It is not clear which is the best method of iron administration.

STUDY DESIGN

Systematic review and meta-analysis. A search was performed until January 2008 of MEDLINE, Cochrane Central Register of Controlled Trials, conference proceedings in nephrology, and reference lists of included trials.

SETTING & POPULATION

Patients with CKD (stages III to V). We included dialysis patients and patients with CKD not on dialysis therapy (hereafter referred to as patients with CKD).

SELECTION CRITERIA FOR STUDIES

We included all randomized controlled trials regardless of publication status or language.

INTERVENTION

Intravenous (IV) versus oral iron supplementation.

OUTCOMES MEASURES

Primary outcomes assessed: absolute hemoglobin (Hb) level or change in Hb level from baseline. We also assessed all-cause mortality, erythropoiesis-stimulating agent requirement, adverse events, ferritin level, and need for renal replacement therapy in patients with CKD.

RESULTS

13 trials were identified, 6 including patients with CKD and 7 including dialysis patients. Compared with oral iron, there was a significantly greater Hb level in dialysis patients treated with IV iron (weighted mean difference, 0.83 g/dL; 95% confidence interval, 0.09 to 1.57). Meta-regression showed a positive association between Hb level increase and IV iron dose administered and a negative association with baseline Hb level. For patients with CKD, there was a small but significant difference in Hb level favoring the IV iron group (weighted mean difference, 0. 31 g/dL; 95% confidence interval, 0.09 to 0. 53). Data for all-cause mortality were sparse, and there was no difference in adverse events between the IV- and oral-treated patients.

LIMITATIONS

There was significant heterogeneity between trials. Follow-up was limited to 2 to 3 months.

CONCLUSIONS

Our review shows that patients on hemodialysis therapy have better Hb level response when treated with IV iron. For patients with CKD, this effect is small.

Erythropoietin, iron depletion, and relative thrombocytosis: a possible explanation for hemoglobin-survival paradox in hemodialysis

BACKGROUND

High doses of human recombinant erythropoietin (rHuEPO) to achieve hemoglobin levels greater than 13 g/dL in patients with chronic kidney disease appear to be associated with increased mortality.

STUDY DESIGN

We conducted logistic regression and survival analyses in a retrospective cohort of long-term hemodialysis patients to examine the hypothesis that the induced iron depletion with resultant relative thrombocytosis may be a possible contributor to the link between the high rHuEPO dose-associated hemoglobin level of 13 g/dL or greater and mortality.

SETTING & PARTICIPANTS

The national database of a large dialysis organization (DaVita) with 40,787 long-term hemodialysis patients during July to December 2001 and their survival up to July 2004 were examined.

PREDICTORS

Hemoglobin level, platelet count, and administered rHuEPO dose during each calendar quarter.

OUTCOMES & OTHER MEASUREMENTS

Case-mix-adjusted 3-year all-cause mortality and measures of iron stores, including serum ferritin and iron saturation ratio.

RESULTS

Higher platelet count was associated with lower iron stores and greater prescribed rHuEPO dose. Compared with a hemoglobin level of 12 to 13 g/dL, a hemoglobin level of 13 g/dL or greater was associated with increased mortality in the presence of relative thrombocytosis, ie, platelet count of 300,000/microL or greater (case-mix-adjusted death-rate ratio, 1.21; 95% confidence limits, 1.02 to 1.44; P = 0.03) as opposed to the absence of relative thrombocytosis (death-rate ratio, 1.04; 95% confidence limits, 0.98 to 1.08; P = 0.1). A prescribed rHuEPO dose greater than 20,000 U/wk was associated with a greater likelihood of iron depletion (iron saturation ratio < 20%) and relative thrombocytosis (case-mix-adjusted odds ratio, 2.53; 95% confidence limits, 2.37 to 2.69; and 1.36; 95% confidence limits, 1.30 to 1.42, respectively; P < 0.001) and increased mortality during 3 years (death-rate ratio, 1.59; 95% confidence limits, 1.54 to 1.65; P < 0.001).

LIMITATIONS

Our results may incorporate uncontrolled confounding. Achieved hemoglobin level may have different mortality predictability than targeted hemoglobin level.

CONCLUSIONS

Iron depletion and associated relative thrombocytosis might contribute to increased mortality when administering high rHuEPO doses to achieve hemoglobin levels of 13 g/dL or greater in long-term hemodialysis patients. Randomized trials are needed to test these observational associations.