Hemoglobin variability and mortality in ESRD

Evaluation of maintenance of stable haemoglobin levels in haemodialysis patients converting from epoetin or darbepoetin to monthly intravenous C.E.R.A.: the MIRACEL study

BACKGROUND AND OBJECTIVES

C.E.R.A., a continuous erythropoietin receptor activator, offers once-monthly dosing without compromising haemoglobin control. This study was undertaken to examine whether monthly C.E.R.A. using pre-filled syringes maintains stable haemoglobin levels when administered according to local clinical judgement.

RESEARCH, DESIGN AND METHODS

MIRACEL was a prospective, open-label, single-arm, multicentre study performed at 90 nephrology centres in Germany. After a 2-month screening phase, haemodialysis patients receiving epoetin or darbepoetin were converted to monthly intravenous C.E.R.A., with a 5-month titration phase followed by a 2-month evaluation phase.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov: NCT00413894 RESULTS: Of 661 patients screened, 424 (64.1%) started C.E.R.A. therapy (previous treatment: 72.2% epoetin, 27.8% darbepoetin); 416 were eligible for inclusion in the intent-to-treat population. A mean of two C.E.R.A. dose changes were required during the 7-month treatment period. The primary efficacy variable, haemoglobin within 11-12.5 g/dL or 10-13 g/dL during the evaluation phase, was achieved in 109 (30.8%) and 265 (74.9%) of the 354 evaluable patients, respectively, with no differences observed between patients formerly receiving epoetin or darbepoetin or different dosing frequencies. During the screening, titration and evaluation phases, mean haemoglobin was 11.7 +/- 0.7 g/dL, 11.6 +/- 0.9 g/dL and 11.4 +/- 1.0 g/dL, respectively, and 90.6% (377/416), 70.4% (293/416) and 82.9% (345/416) of patients exhibited < or = 1 g/dL change from phase-specific individual means. C.E.R.A. was well-tolerated with a safety profile similar to that reported in phase III studies.

CONCLUSIONS

In this single-arm, open-label, multicentre study, conversion of a large population of haemodialysis patients from epoetin or darbepoetin to monthly C.E.R.A. administration using pre-filled syringes was shown to be practical, convenient and offer good control of haemoglobin levels, regardless of the previous type of therapy or dosing frequency.

Sex-specific association of time-varying haemoglobin values with mortality in incident dialysis patients

BACKGROUND

Previous studies in dialysis patients showed an association between haemoglobin levels and all-cause mortality, however, without addressing sex differences.

METHODS

We followed up 235 incident dialysis patients of the region of Vorarlberg in a prospective cohort study applying a time-dependent Cox regression analysis using all the measured laboratory values for up to more than 7 years. In total, 12 242 haemoglobin measurements with a median of 47 (range 3-270) per patient were available to evaluate the impact of haemoglobin levels and their variability on all-cause mortality in a sex-stratified analysis. Non-linear P-splines were used to allow a flexible modelling of the association with mortality.

RESULTS

We observed an inverse relationship between the increasing haemoglobin values and the decreasing risk of mortality. The linear component of the non-linear spline was highly significant for both men (P = 0.00005) and women (P = 0.0000000052). The non-linear component was also significant but less pronounced than the linear component. The inverse relationship was clear to see haemoglobin levels of up to 12-13 g/L in women, which reached a plateau for the higher values of haemoglobin. For men, an inverse trend was observed but clearly attenuated when compared to women. After adjustment for additional parameters of inflammation and malnutrition as well as diabetes, the linear component was more significant in women (P = 0.0018) than in men (P = 0.023).

CONCLUSIONS

This study applied for the first time a time-dependent Cox regression analysis over a long-term observation period of several years using all available measurements. Besides the methodological advantages, our data indicate a sex-specific linear as well as non-linear effect of haemoglobin levels on all-cause mortality, which was markedly more pronounced in women.

Hemoglobin variability in patients with chronic kidney disease in the Netherlands

PURPOSE

Hemoglobin cycling has been reported in hemodialysis patients treated with erythropoiesis-stimulating agents (ESA) and is associated with increased mortality. Information on hemoglobin cycling in Europe is limited. We investigated hemoglobin variability in the Netherlands. Hemodialysis and peritoneal dialysis patients were studied and pre-dialysis patients were enrolled.

METHODS

This observational retrospective study was executed in a Dutch dialysis center. We studied 157 patients from 2005 to 2007: 56 hemodialysis, 12 peritoneal dialysis and 29 pre-dialysis patients, all treated with ESA; and 60 pre-dialysis patients without ESA. Patients were divided on the basis of their pattern of hemoglobin fluctuation around a range of 11-12 g/dL. In dialysis patients, the amount of time that hemoglobin remained within that range was calculated. For all patients, the magnitude of hemoglobin fluctuations was assessed (i.e. the difference between hemoglobin maximum and minimum) and data on ESA dose changes and hospitalizations were collected.

RESULTS

None of the ESA treated patients had hemoglobin levels stable within the target range over a one-year period. Pre-dialysis patients without ESA also showed variable hemoglobin levels. A stepwise decrease in the magnitudes of hemoglobin fluctuation was observed in the hemodialysis patients, peritoneal dialysis patients, pre-dialysis patients using ESA, and the pre-dialysis patients without ESA, respectively.

CONCLUSION

In the Netherlands, hemoglobin variability is common in hemodialysis and peritoneal dialysis patients, but also in pre-dialysis patients. The results of this study warrant further research into the relationship between hemoglobin variability and clinical outcomes.

Use of 12x/month haemoglobin monitoring with a computer algorithm reduces haemoglobin variability

BACKGROUND

Haemoglobin variability may be associated with increased death. Frequent haemoglobin monitoring may allow earlier detection of trends in haemoglobin slopes, alerting staff to intercurrent events. The more frequent haemoglobin values may provide early evidence of response to erythropoietin (EPO) doses, and allow more appropriate anaemia management. Our objective is to assess whether frequent haemoglobin monitoring data (12x/month) using a computer algorithm (AMIE, Leeds, UK) will reduce haemoglobin variability compared with 1x/month monitoring.

METHODS

We performed an observational case-control study of 44 unselected patients, comprising one dialysis facility measuring Crit-Line haemoglobin, lab haemoglobin, standard deviation of residuals as surrogate of haemoglobin variability and EPO dosing.

RESULTS

Haemoglobin variability and 'percent in target haemoglobin range' significantly improved with 12x/month haemoglobin results using a computer algorithm. There was also a non-significant trend toward for lower EPO doses.

CONCLUSION

Use of a computer algorithm to analyse 12x/month haemoglobin values provides early evidence of haemoglobin trends and allows more appropriate anaemia management, with decreased haemoglobin variability, lower EPO doses and more patients achieving target haemoglobin.

Iron, inflammation, dialysis adequacy, nutritional status, and hyperparathyroidism modify erythropoietic response

BACKGROUND AND OBJECTIVES

The erythropoietic response in hemodialysis patients depends on several physiologic factors. Most epidemiologic studies include the effect of these factors by representing them as confounders. This study tested the hypothesis that iron stores, inflammation, dialysis adequacy, nutritional status, and hyperparathyroidism act as nonlinear effect modifiers of the erythropoietic response and quantified the magnitude of those effects over clinically relevant ranges.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The following retrospective data from 209 hemodialysis patients receiving Epoetin alfa (Epo) were collected: monthly: predialysis hemoglobin (Hgb), transferrin saturation, serum albumin, dialysis adequacy (Kt/V); quarterly: predialysis serum ferritin and intact parathyroid hormone over a period of 13 to 69 months. The study analyzed the dynamic relationship between hemoglobin and Epo, considering nonlinear effect modification by ferritin, transferrin saturation, Kt/V, albumin, and parathyroid hormone individually.

RESULTS

Maximum Hgb response to Epo was achieved for serum ferritin between 350 and 500 ng/ml, transferrin saturation greater than 30%, Kt/V greater than 1.4, and albumin greater than 3.8 g/dl. Hgb sensitivity to Epo decreases by about 30% as parathyroid hormone increases from 0 through 1000 pg/ml.

CONCLUSIONS

Serum ferritin, transferrin saturation, Kt/V, serum albumin, and intact parathyroid hormone are markers of nonlinear effect modification of the erythropoietic response in hemodialysis patients.

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.

Maintaining over time clinical performance targets on anaemia correction in unselected population on chronic dialysis at 20 Italian centres. Data from a retrospective study for a clinical audit

BACKGROUND

The Italian and European Best Practice Guidelines (EBPG) recommend a target haemoglobin value greater than 11 g/dl in most patients with Chronic Kidney Diseases. However, it is still difficult to maintain these values at a steady rate. Thus, the main aim of the study was to evaluate, throughout 2005, how many patients steadily maintained the performance targets related to anaemia treatment.

METHODS

The survey was conducted on 3283 patients on haemodialysis (HD) and peritoneal dialysis (PD) at 20 Italian dialysis centres. 540 patients were randomly selected; each centre provided a statistically significant sample proportional to its total number of patients. Maintenance of the following target levels was assessed over time: Haemoglobin (HB) 11-12 gr/dl; Iron: 60-160 mcg/dl; Ferritin: 30-400 mcg/l; Transferrin: 200-360 mg/dl; Transferrin saturation percentage (TSAT %):> 25 <50; Dialysis doses (KT/V): >1.2 <2.0 for non-diabetic HD patients; >1.5 <2.2 for diabetic HD patients; DP: >1.8 <2.5.Outcome included:1- Percentage of target maintenance for each parameter.2- Erythropoietin dose in relation to dialysis techniques, presence of cancer or myeloma, diabetic status, Vitamin B therapy.3- Erythropoietin dose (International Units/kg/week) (IU/kg/wk) depending on: haemoglobin values, hospitalization of more than 3 days.

RESULTS

Mean age was 65.1; mean haemoglobin concentration over the whole population was 11.3 gr/dl (Standard Deviation (SD): 0.91). The clinical performance targets were maintained over time as follows: HB: 4.3% (Mean 11.43 gr/dl) (SD: 0.42); Ferritin: 71.1% (Mean: 250.23 mcg/L (SD:104.07); Iron: 95.0% (Mean 59.79 mcg/dl)(SD:16.76); Transferrin: 44.8% (Mean 216.83 mg/dl) (SD: 19,50); TSAT %: in 8.4% (Mean: 34.33% (SD: 6.56); HD KT/V: 61.0% (Mean:1.46) (SD: 0.7); PD KT/V:31.4% (Mean: 2.10) (SD: 0.02). The average weekly dose of Erythropoietin (IU/Kg/Wk) was significantly lower for the peritoneal dialysis technique; the higher haemoglobin values, the lower the Erythropoietin dose (IU/Kg/Wk).

CONCLUSION

A very low percentage of patients maintained haemoglobin target values over time. We need to identify precise criteria to evaluate the stability over time of clinical performance targets proposed by the guidelines.

Use of agents stimulating erythropoiesis in digestive diseases

Anemia is the most common complication of inflammatory bowel disease (IBD). Control and inadequate treatment leads to a worse quality of life and increased morbidity and hospitalization. Blood loss, and to a lesser extent, malabsorption of iron are the main causes of iron deficiency in IBD. There is also a variable component of anemia related to chronic inflammation. The anemia of chronic renal failure has been treated for many years with recombinant human erythropoietin (rHuEPO), which significantly improves quality of life and survival. Subsequently, rHuEPO has been used progressively in other conditions that occur with anemia of chronic processes such as cancer, rheumatoid arthritis or IBD, and anemia associated with the treatment of hepatitis C virus. Erythropoietic agents complete the range of available therapeutic options for treatment of anemia associated with IBD, which begins by treating the basis of the inflammatory disease, along with intravenous iron therapy as first choice. In cases of resistance to treatment with iron, combined therapy with erythropoietic agents aims to achieve near-normal levels of hemoglobin/hematocrit (11-12 g/dL). New formulations of intravenous iron (iron carboxymaltose) and the new generation of erythropoietic agents (darbepoetin and continuous erythropoietin receptor activator) will allow better dosing with the same efficacy and safety.

Generics: need for clinical concern?

The market of generic drugs is in continuous development in all countries, including Belgium. Their low cost explains their success in western and developed countries. However, clinical concerns have been raised when generics are used. Indeed, various studies suggest that generic substitution can be associated with reduced efficacy or (and) increased side-effects, particularly with drugs used in severe diseases or pathological states such as epilepsy, cardiac arrhythmia, prevention of graft-rejection, ... The generic drugs must have systemic bioavailability similar to that of the original drug. Thus, they have supposed similar therapeutic bioequivalence. However, similar pharmacokinetics does not imply identical therapeutic activity, particularly with drugs having narrow therapeutic indices such as anti-epileptics, anti-arrythmics ... In this case, switchability rather than prescribability may cause problems. Low pharmaceutical quality is more frequent when drugs are produced in certain countries, in some cases causing a real concern when activity and safety are considered.

Hemoglobin variability in chronic kidney disease: a cross-sectional study

BACKGROUND

The ability to maintain dialysis patients' hemoglobin (Hgb) within narrow targets remains a significant clinical problem. This study was designed to determine the variability in Hgb values for patients with chronic kidney disease (CKD) receiving or not receiving erythropoiesis-stimulating agents (ESAs) compared with patients on dialysis receiving ESAs.

METHODS

This cross-sectional review of anemia management in CKD and dialysis patients analyzed Hgb variability by patient-year, defined as the coefficient of variability calculated for individual patients. One hundred thirty-seven CKD patient-years and 350 dialysis patient-years were available for analysis. Hgb variability was defined as the coefficient of variability calculated as the individual patient's Hgb standard deviation divided by the patient's mean Hgb times 100.

RESULTS

The coefficient of variability in Hgb values were significantly less in patients with CKD not treated with ESAs than in patients with CKD treated with ESAs whether they were receiving dialysis (medians: 3.96 versus 8.53%, P < 0.05) or not receiving dialysis (medians: 3.96 versus 7.37%, P < 0.05).

CONCLUSION

CKD and hemodialysis patients receiving treatment with ESAs have significantly greater Hgb variability than patients with CKD not receiving ESAs. This finding suggests that the current practice pattern for the administration of exogenous ESAs is partly responsible for the observed Hgb variability.

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.

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.

Epoetin therapy and hemoglobin level variability in nondialysis patients with chronic kidney disease

BACKGROUND AND OBJECTIVES

Intrapatient variability of hemoglobin (Hb) is a newly proposed determinant of adverse outcome in chronic kidney disease (CKD). We evaluated whether intensity of epoetin therapy affects Hb variability and renal survival in nondialysis CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We calculated the individual therapeutic index (TI) for epoetin (EPO; difference between rates of visits that required EPO dosage change and those with effective EPO change) from 1198 visits during the first year of EPO in 137 patients. Renal death was registered in the subsequent 18.1 mo. Analysis was made by TI tertile (lower, middle, and higher; i.e., from more to less intensive therapy).

RESULTS

Main features and visit number were similar in tertiles. Lower Hb response to first EPO dosage was an independent predictor of higher TI (P = 0.002). The area under the curve for Hb (11.56 +/- 0.87, 11.46 +/- 1.20, and 10.95 +/- 1.48 g/dl per yr; P = 0.040) decreased from lower to higher tertile. Hb variability increased in parallel, as shown by the reduction of time with Hb at target (time in target, from 9.2 +/- 2.0 to 3.0 +/- 2.2 mo; P < 0.0001) and the wider values of within-patient Hb standard deviation (from 0.70 to 0.96; P = 0.005) and Hb fluctuations across target (P < 0.0001). In Cox analyses (hazard ratio [95% confidence interval]), risk for renal death was increased in the middle and higher tertiles (2.79 [1.36 to 5.73] and 2.94 [1.40 to 6.20]) and reduced by longer time in target (0.90 [0.83 to 0.98]).

CONCLUSIONS

Lack of adjustment of EPO worsens Hb variability in CKD. Hb variability may be associated with renal survival, but further studies are needed to explore the association versus causal relationship.

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.

Inflammation and its impact on anaemia in chronic kidney disease: from haemoglobin variability to hyporesponsiveness

The availability of erythropoiesis-stimulating agents (ESAs) has revolutionized the treatment of anaemia in patients with chronic kidney disease. However, maintaining patients at haemoglobin (Hb) levels that are both safe and provide maximal benefit is a continuing challenge in the field. Based on emerging data on the potential risks of Hb treatment targets >13 g/dL, treatment targets have recently been lowered. In the latest revision (March 2008) of the European product labelling for the ESA class of drugs, the target treatment range was lowered to 10–12 g/dL. Fluctuation of Hb levels or ‘Hb variability’ during treatment with ESAs is a well-documented phenomenon. Hb levels that are either too high or too low may have an adverse effect on patient outcomes; thus, it is important to understand the causes of Hb variability in order to achieve optimal treatment. Several factors are believed to contribute to variation in the Hb level, including patient comorbidities and intercurrent events. Inflammation is also an important factor associated with Hb variability, and the consequences of persistent inflammatory activity are far-reaching in affected patients. This review addresses the complex role of inflammation in chronic kidney disease, as evidenced by the apparent state of deranged inflammatory markers. The mechanisms by which inflammatory cytokines may affect the response to ESAs, the development of anaemia and poor treatment outcomes are also examined. In addition, various options for intervention to enhance the response to ESAs in haemodialysis patients with inflammation are considered.

Hemoglobin control, ESA resistance, and regular low-dose IV iron therapy: a review of the evidence

Anemia management in hemodialysis patients has progressed following the introduction of erythropoiesis-stimulating agents (ESAs) and intravenous (IV) iron. However, maintaining a stable hemoglobin (Hb) level can be challenging. Patient comorbidities and variable dosage administrations of ESA therapy can lead to great variability in Hb concentrations over time. Fluctuating Hb levels is associated with increased complications. This article reviews factors that affect Hb control, with a focus on management practices (e.g., regular low-dose administration of IV iron) that can help improve anemia management.

Route of epoetin administration influences hemoglobin variability in hemodialysis patients

BACKGROUND

Compared to the intravenous route, subcutaneous administration of epoetin requires lower dose and will be an attractive option for cost containment when bundling for dialysis is implemented. Hemoglobin variability defined as fluctuation of hemoglobin over time has not been well studied with respect to the route of administration.

METHODS

157 prevalent-hemodialysis subjects were analyzed from an open-label, randomized study that compared the intravenous to the subcutaneous route of epoetin with identical weight-based dosing algorithm. Hemoglobin variability was defined as the number of weeks hemoglobin is outside the target range of 10-11 g/dl. Sensitivity analysis was performed.

RESULTS

78 subjects in the intravenous and 79 in the subcutaneous group entered the 24-week dose maintenance phase. Baseline covariates were similar in both groups except for the dose of epoetin (lower in subcutaneous) and dialysis vintage (longer in intravenous). Patients on subcutaneous epoetin were outside the target range more weeks (p = 0.04) and had higher standard deviation of hemoglobin (p = 0.01) compared to the intravenous group.

CONCLUSIONS

The subcutaneous route of epoetin was associated with modestly higher hemoglobin variability, probably reflecting greater sensitivity of the subcutaneous route and/or identical epoetin-dosing algorithm employed in both the arms. This study could serve as an important guide when bundling for dialysis services is implemented as switching from intravenous to subcutaneous administration is likely to occur.

Association of hemoglobin variability and mortality among contemporary incident hemodialysis patients

BACKGROUND AND OBJECTIVES

Evidence exists that variability in hemoglobin may be an independent risk factor for mortality among hemodialysis patients. These observations were based on a 1996 cohort, a time when anemia management differed greatly from present. Design, settings, participants and measurements: A retrospective cohort study of patients incident to Fresenius Medical Care units between 2004 and 2005 (n = 6644). Hemoglobin variability (Hgb-Var) was defined for each subject as the residual SD of a linear regression model of time on hemoglobin.

RESULTS

The mean (SD) of Hgb-Var was 1.13 (0.55) g/dl. In the primary analysis, each g/dl increase of Hgb-Var was associated with an adjusted hazard ratio (95% confidence interval) for all-cause mortality of 1.11 (0.92 to 1.33). No significant interaction with Hgb-Var and mortality was found on the basis of age (P = 0.22), arterial disease (P = 0.45), Hgb slope (P = 0.68), or mean Hgb (P = 0.78). When Hgb-Var was defined by a regression model that included a quadratic term for time (enabling descriptions of curvilinear hemoglobin trajectories), model fit was greatly improved (P for difference <0.001). The corresponding adjusted hazard ratio (95% confidence interval) for all-cause mortality was 1.17 (0.93 to 1.49).

CONCLUSIONS

Hgb-Var was not found to be associated with all-cause mortality when examined in a contemporary incident hemodialysis population. More research is needed to determine whether differences in these findings compared with prior analyses relate to temporal trends in anemia management or from differences in the relationship between Hgb-Var and outcomes among incident versus prevalent hemodialysis patients.

[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.

The effect of altitude on dosing and response to erythropoietin in ESRD

For poorly understood reasons, patients with end-stage renal disease (ESRD) differ substantially in their response to treatment with recombinant erythropoietin (EPO). Because hypoxia influences many of the biologic pathways involved in erythropoiesis, the altitude at which a patient lives may affect the dose-response relationship of EPO. In this retrospective cohort study, clinical data from 341,737 incident hemodialysis patients registered in the U.S. Renal Data System were combined with elevation data from the U.S. Geological Survey to address this question. Higher altitude was associated with smaller EPO doses and higher hematocrit levels. For example, compared with patients at sea level, patients living above 6000 ft received 19% less EPO (12.9 versus 15.9 thousand units/wk) but had hematocrit levels 1.1 points higher (35.7% versus 34.6%). These associations were found within subgroups defined by sex, race, age, calendar time, cause of ESRD, and dialysis center profit status, and persisted after adjustment for various potential confounding factors. Furthermore, resistance to EPO decreased with elevation. Our results suggest that ESRD patients living at high altitude either increase endogenous EPO production or respond better to endogenous and exogenous EPO.