Safety of intravenous iron in hemodialysis patients.

Among end-stage renal disease patients maintained by hemodialysis, anemia has been managed primarily through erythropoiesis-stimulating agents (ESAs) and intravenous (IV) iron. Following concerns about the cardiovascular (CV) safety of ESAs and changes in the reimbursement policies in Medicare's ESRD program, the use of IV iron has increased. IV iron supplementation promotes hemoglobin production and reduces ESA requirements, yet there exists relatively little evidence on the long-term safety of iron supplementation in hemodialysis patients. Labile iron can induce oxidative stress and is also essential in bacterial growth, leading to concerns about IV iron use and risk of CV events and infections in hemodialysis patients. Existing randomized controlled trials provide little evidence about safety due to insufficient power and short follow-up; recent observational studies have been inconsistent, but some have associated iron exposure with increased risk of infections and CV events. Given the widespread use and potential safety concerns related to IV iron, well-designed large prospective studies are needed to assess to identify optimal strategies for iron administration that maximize its benefits while avoiding potential risks.

Dynamics of cinacalcet use and biochemical control in hemodialysis patients: a retrospective New-user cohort design.

BACKGROUND: Cinacalcet is used to treat secondary hyperparathyroidism among hemodialysis patients. Large-scale epidemiologic studies describing patterns of cinacalcet use, effects on parathyroid hormone (PTH), calcium, and phosphorous levels, and predictors of discontinuation have not been previously reported. METHODS: This retrospective cohort study used a clinical database of a large U.S. dialysis provider (2007-2010) merged with administrative data from the United States Renal Data System. Among new users of cinacalcet with Medicare coverage, trends in PTH, calcium, and phosphorus were measured in 30-day intervals following cinacalcet initiation. RESULTS: Seventeen thousand seven hundred sixty-three eligible initiators contributed 111,047 30-day follow-up intervals. Of these, 56 % discontinued cinacalcet by month 4. Of those discontinuing, 76.3 % reinitiated. Mean values of PTH, calcium, and phosphorus decreased to recommended levels within 4 months following initiation. Proximal PTH levels < 150 pg/mL were associated with discontinuation: HR = 1.23 (95 % CI: 1.12, 1.36), whereas low calcium (< 7.5 mg/dL) was suggestive of an association, HR = 1.09 (95 % CI 0.91, 1.32). Being in the Part D gap period increased discontinuation risk: HR = 1.09 (95 % CI: 1.03, 1.16). Low-income subsidy status decreased discontinuation risk: HR = 0.77 (95 % CI 0.69, 0.86). Predictors of reinitiation included low-income subsidy, HR = 1.32 (95 % CI 1.22, 1.43); higher albumin level, HR = 1.23 (95 % CI 1.10, 1.36) and higher calcium level, HR = 1.26 (95 % CI 1.19, 1.33). CONCLUSIONS: Substantial and expected declines in laboratory values occurred following cinacalcet initiation. Early discontinuation and reinitiation of cinacalcet were common and may have occurred for clinical and economic reasons.

Effectiveness and safety of dabigatran and warfarin in real-world US patients with non-valvular atrial fibrillation: a retrospective cohort study.

BACKGROUND: The recent availability of dabigatran, a novel oral anticoagulant, provided a new treatment option for stroke prevention in atrial fibrillation beyond warfarin, the main therapy for years. Little is known about their real-world comparative effectiveness and safety, even less among patient demographic and clinical subgroups. METHODS AND RESULTS: Using a cohort of non-valvular AF patients initiating anticoagulation from October 2010 to December 2012 drawn from a large US database of commercial and Medicare supplement claims, we applied propensity score weights to Cox proportional hazards regression to assess the comparative effectiveness and safety of dabigatran versus warfarin. Analyses were repeated among clinical and demographic subgroups using stratum-specific propensity scores as an exploratory analysis. Of the 64 935 patients initiating anticoagulation, 32.5% used dabigatran. Compared with warfarin, dabigatran was associated with a lower risk of ischemic stroke or systemic embolism (composite adjusted Hazard Ratio [aHR], 95% CI: 0.86, 95% CI: 0.79 to 0.93), hemorrhagic stroke (aHR: 0.51, 0.40 to 0.65), and acute myocardial infarction (aHR: 0.88, 95% CI: 0.77 to 0.99), and no relation was seen between dabigatran and the composite harm outcome (aHR: 0.94, 95% CI: 0.87 to 1.01). However, dabigatran was associated with a higher risk of gastrointestinal bleeding (aHR: 1.11, 95% CI: 1.02 to 1.22). Estimates of effectiveness and safety appeared to be mostly similar across subgroups. CONCLUSIONS: Dabigatran could be a safe and potentially more effective alternative to warfarin in patients with atrial fibrillation managed in routine practice settings.

Comparative short-term safety of bolus versus maintenance iron dosing in hemodialysis patients: a replication study.

BACKGROUND: Recent research has reported that patients receiving bolus (frequent large doses to achieve iron repletion) versus maintenance dosing of iron have an increased short-term risk of infection, but a similar risk of cardiovascular events. We sought to determine whether these findings could be replicated using the same methods and a different data source. METHODS: Clinical data from 6,605 patients of a small U.S. dialysis provider merged with Medicare claims data were examined. Iron dosing patterns (bolus, maintenance, no iron) were identified during 1-month exposure periods and cardiovascular and infection-related outcomes were assessed during 3-month follow-up periods. The effects of bolus versus maintenance dosing were assessed using Cox proportional hazards regression analyses to estimate hazard ratios and semiparametric additive risk models to estimate hazard rate differences, controlling for demographic and clinical characteristics, laboratory values and medications, and comorbidities. RESULTS: 48,050 exposure/follow-up periods were examined. 13.9 percent of the exposure periods were bolus dosing, 49.3 percent were maintenance dosing, and the remainder were no iron use. All of the adjusted hazard ratios were >1.00 for the infection-related outcomes, suggesting that bolus dosing increases the risk of these events. The effects were greatest for hospitalized for infection of any major organ system (hazard ratio 1.13 (1.03, 1.24)) and use of intravenous antibiotics (hazard ratio 1.08 (1.02, 1.15). When examining the subgroup of individuals with catheters, the hazard ratios for the infection-related outcomes were generally greater than in the overall sample. There was little association between type of dosing practice and cardiovascular outcomes. CONCLUSIONS: Results of this study provide further evidence of the association between bolus dosing and increased infection risk, particularly in the subgroup of patients with a catheter, and of the lack of an association between dosing practices and cardiovascular outcomes.

Trends in anemia care in older patients approaching end-stage renal disease in the United States (1995-2010).

IMPORTANCE: Anemia is common in patients with advanced chronic kidney disease. Whereas the treatment of anemia in patients with end-stage renal disease (ESRD) has attracted considerable attention, relatively little is known about patterns and trends in the anemia care received by patients before they start maintenance dialysis or undergo preemptive kidney transplantation. OBJECTIVE: To determine the trends in anemia treatment received by Medicare beneficiaries approaching ESRD. DESIGN, SETTING, AND PARTICIPANTS: Closed cohort study in the United States using national ESRD registry data (US Renal Data System) of patients 67 years or older who initiated maintenance dialysis or underwent preemptive kidney transplantation between 1995 and 2010. All eligible patients had uninterrupted Medicare (A+B) coverage for at least 2 years before ESRD. EXPOSURE: Time, defined as calendar year of incident ESRD. MAIN OUTCOMES AND MEASURES: Use of erythropoiesis-stimulating agents (ESA), intravenous iron supplements, and blood transfusions in the 2 years prior to ESRD; hemoglobin concentration at the time of ESRD. We used multivariable modified Poisson regression to estimate utilization prevalence ratios (PRs). RESULTS: Records of 466,803 patients were analyzed. The proportion of patients with incident ESRD receiving any ESA in the 2 years before increased from 3.2% in 1995 to a peak of 40.8% in 2007; thereafter, ESA use decreased modestly to 35.0% in 2010 (compared with 1995; PR, 9.85 [95% CI, 9.04-10.74]). Among patients who received an ESA, median time from first recorded ESA use to ESRD increased from 120 days in 1995 to 337 days in 2010. Intravenous iron administration increased from 1.2% (1995) to 12.3% (2010; PR, 9.20 [95% CI, 7.97-10.61]). The proportion of patients receiving any blood transfusions increased monotonically from 20.6% (1995) to 40.3% (2010; PR, 1.88 [95% CI, 1.82-1.95]). Mean hemoglobin concentrations were 9.5 g/dL in 1995, increased to a peak of 10.3 g/dL in 2006, and then decreased moderately to 9.9 g/dL in 2010. CONCLUSIONS AND RELEVANCE: Between 1995 and 2010, older adults approaching ESRD were increasingly more likely to be treated with ESAs and to receive intravenous iron supplementation, but also more likely to receive blood transfusions.

A non-experimental study of oral anticoagulation therapy initiation before and after national patient safety goals.

OBJECTIVES: The Joint Commission revised its National Patient Safety Goals (NPSGs) to include oral anticoagulation therapy (OAT) in 2008. We sought to examine the effect of including OAT in The Joint Commission's NPSGs on historically low rates of OAT initiation for individuals with incident atrial fibrillation (AF). SETTING: Southeastern state in the USA. PARTICIPANTS: North Carolina State Health Plan claims data from 944 500 individuals enrolled between 1 January 2006 and 31 December 2010, supplemented with data from the Area Resource File and Online Survey, Certification and Reporting data network. We evaluated OAT initiation before and after the 2008 NPSGs revisions in a retrospective cohort new user design with an AF intervention group and two control groups: a positive control-patients estimated to be at very high risk of thromboembolism (mechanical heart valve and pulmonary embolism); and a negative control-patients with very low perceived risk of thromboembolism (paroxysmal AF). We developed multivariable models using a difference-in-difference parameterisation. Effects were estimated with generalised estimating equations. PRIMARY OUTCOME MEASURE: OAT initiation, a binary outcome defined as having a prescription drug claim for warfarin within 30 days of the index claim. RESULTS: OAT initiation was low (26.8%) for eligible individuals with incident AF in 2006-2008 but increased after NPSGs implementation (31.7%, p=0.022). OAT initiation was high but decreased in the positive control group (67.5% vs 62.0%, p=0.003). Multivariate analysis resulted in a relative 11% (95% CI (4% to 18%), p<0.01) increase in OAT initiation for incident AF patients. CONCLUSIONS: We document a substantial increase in guideline concordant OAT initiation in incident AF after the establishment of NPSGs, suggesting that regulatory healthcare agency initiatives can influence clinical practice.

Intravenous iron supplementation practices and short-term risk of cardiovascular events in hemodialysis patients.

BACKGROUND & OBJECTIVES: Intravenous iron supplementation is widespread in the hemodialysis population, but there is uncertainty about the safest dosing strategy. We compared the safety of different intravenous iron dosing practices on the risk of adverse cardiovascular outcomes in a large population of hemodialysis patients. DESIGN SETTINGS PARTICIPANTS & MEASUREMENTS: A retrospective cohort was created from the clinical database of a large dialysis provider (years 2004-2008) merged with administrative data from the United States Renal Data System. Dosing comparisons were (1) bolus (consecutive doses ≥ 100 mg exceeding 600 mg during one month) versus maintenance (all other iron doses during the month); and (2) high (> 200 mg over 1 month) versus low dose (≤ 200 mg over 1 month). We established a 6-month baseline period (to identify potential confounders and effect modifiers), a one-month iron exposure period, and a three-month follow-up period. Outcomes were myocardial infarction, stroke, and death from cardiovascular disease. RESULTS: 117,050 patients contributed 776,203 unique iron exposure/follow-up periods. After adjustment, we found no significant associations of bolus dose versus maintenance, hazards ratio for composite outcome, 1.03 (95% C.I. 0.99, 1.07), or high dose versus low dose intravenous iron, hazards ratio for composite outcome, 0.99 (95% C.I. 0.96, 1.03). There were no consistent associations of either high or bolus dose versus low or maintenance respectively among pre-specified subgroups. CONCLUSIONS: Strategies favoring large doses of intravenous iron were not associated with increased short-term cardiovascular morbidity and mortality. Investigation of the long-term safety of the various intravenous iron supplementation strategies may still be warranted.

Infection risk with bolus versus maintenance iron supplementation in hemodialysis patients.

Intravenous iron may promote bacterial growth and impair host defense, but the risk of infection associated with iron supplementation is not well defined. We conducted a retrospective cohort study of hemodialysis patients to compare the safety of bolus dosing, which provides a large amount of iron over a short period of time on an as-needed basis, with maintenance dosing, which provides smaller amounts of iron on a regular schedule to maintain iron repletion. Using clinical data from 117,050 patients of a large US dialysis provider merged with data from Medicare's ESRD program, we estimated the effects of iron dosing patterns during repeated 1-month exposure periods on risks of mortality and infection-related hospitalizations during the subsequent 3 months. Of 776,203 exposure/follow-up pairs, 13% involved bolus dosing, 49% involved maintenance dosing, and 38% did not include exposure to iron. Multivariable additive risk models found that patients receiving bolus versus maintenance iron were at increased risk of infection-related hospitalization (risk difference [RD], 25 additional events/1000 patient-years; 95% confidence interval [CI], 16 to 33) during follow-up. Risks were largest among patients with a catheter (RD, 73 events/1000 patient-years; 95% CI, 48 to 99) and a recent infection (RD, 57 events/1000 patient-years; 95% CI, 19 to 99). We also observed an association between bolus dosing and infection-related mortality. Compared with no iron, maintenance dosing did not associate with increased risks for adverse outcomes. These results suggest that maintenance iron supplementation may result in fewer infections than bolus dosing, particularly among patients with a catheter.

The comparative short-term effectiveness of iron dosing and formulations in US hemodialysis patients.

BACKGROUND: Intravenous iron is used widely in hemodialysis, yet there are limited data on the effectiveness of contemporary dosing strategies or formulation type. METHODS: We conducted a retrospective cohort study using data from the clinical database of a large dialysis provider (years 2004-2008) merged with administrative data from the US Renal Data System to compare the effects of intravenous iron use on anemia management. Dosing comparisons were bolus (consecutive doses ≥100 mg exceeding 600 mg during 1 month) versus maintenance (all other iron doses during the month); and high (>200 mg over 1 month) versus low dose (≤200 mg over 1 month). Formulation comparison was administration of ferric gluconate versus iron sucrose over 1 month. Outcomes were hemoglobin, epoetin dose, transferrin saturation, and serum ferritin during 6 weeks of follow-up. RESULTS: We identified 117,050 patients for the dosing comparison, and 66,207 patients for the formulation comparison. Bolus dosing was associated with higher average adjusted hemoglobin (+0.23 g/dL; 95% confidence interval [CI], 0.21-0.26), transferrin saturation (+3.31%; 95% CI, 2.99-3.63), serum ferritin (+151 µg/L; 95% CI, 134.9-168.7), and lower average epoetin dose (-464 units; 95% CI, -583 to -343) compared with maintenance. Similar trends were observed with high-dose iron versus low-dose. Iron sucrose was associated with higher adjusted average hemoglobin (+0.16 g/dL; 95% CI, 0.12-0.19) versus ferric gluconate. CONCLUSIONS: Strategies favoring large doses of intravenous iron or iron sucrose lead to improved measures of anemia management. These potential benefits should be weighed against risks, which currently remain incompletely characterized.

Changing patterns of anemia management in US hemodialysis patients.

BACKGROUND: Erythropoiesis-stimulating agents and adjuvant intravenous iron have been the primary treatment for anemia in chronic kidney disease. Recent clinical and policy-related events have challenged this traditional paradigm, particularly in regard to erythropoiesis-stimulating agents. Less is known about the impact of these events on intravenous iron use. METHODS: United States Renal Data System data (2002-2008) on Medicare hemodialysis patients were examined. For each patient, monthly intravenous iron dose, erythropoiesis-stimulating agent dose, and hemoglobin values were determined. Data were summarized by calendar quarter and plotted for the entire sample and by demographic, clinical, and facility-level subgroups. Marginal means for these variables also were computed to account for changes in patient characteristics over time. RESULTS: Quarterly iron use increased from 64% in 2002 to 76% in 2008. Mean quarterly iron dose increased from 500 mg in 2002 to 650 mg in 2008. Mean monthly erythropoiesis-stimulating agent dose (per quarter) increased from 2002 to 2006 and then declined. Mean hemoglobin values followed a pattern similar to erythropoiesis-stimulating agent dose. The same patterns in iron, erythropoiesis-stimulating agent dose, and hemoglobin were generally observed across demographic, clinical, facility, and geographic subgroups, with some important differences between subgroups, specifically race and dialysis vintage. CONCLUSIONS: Anemia management patterns have changed markedly between 2002 and 2008, with a steady increase in intravenous iron use even after declines in erythropoiesis-stimulating agent dose and hemoglobin. The clinical impacts of these changes need further evaluation.