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

Duration of untreated psychosis and clinical outcomes of first episode psychosis: An observational and an instrumental variables analysis

AIM

Duration of untreated psychosis (DUP) is considered as a key prognostic variable in psychosis. Yet, it is unclear whether a longer DUP causes worse outcomes or whether reported associations have alternative explanations.

METHODS

Data from 2 cohorts of patients with first episode psychosis were used (n = 2134). Measures of DUP were assessed at baseline and outcomes at 12 months. Regression models were used to investigate the associations between DUP and outcomes. We also investigated whether any associations were replicated using instrumental variables (IV) analysis to reduce the effect of residual confounding and measurement bias.

RESULTS

There were associations between DUP per 1-year increase and positive psychotic symptoms (7.0% in symptom score increase 95% confidence interval (CI) 4.0%, 10.0%, P < .001), worse recovery (risk difference [RD] 0.78, 95%, CI 0.68, 0.83, P < .001) and worse global functioning (0.62 decrease in functioning score 95% CI -1.19, -0.04, P = .035). There was no evidence of an association with negative psychotic symptoms (1.0%, 95%, CI -2.0%, 5.0%, P = .455). The IV analysis showed weaker evidence of associations in the same direction between DUP per 1-year increase and positive psychotic symptoms, recovery and global functioning. However, there was evidence of an inverse association with negative psychotic symptoms (decrease of 15.0% in symptom score 95% CI -26.0%, -3.0%, P = .016).

CONCLUSIONS

We have confirmed previous findings of a positive association between positive psychotic symptoms, global functioning and recovery and DUP using regression analysis. IV analysis shows some support for these findings. Future investigation using IV analysis should be repeated in large data sets.

Methodologic considerations for noninterventional studies of switching from reference biologic to biosimilars

PURPOSE

As more biosimilars become available in the United States, postapproval noninterventional studies describing biosimilar switching and comparing effectiveness and/or safety between switchers and nonswitchers will play a key role in generating real-world evidence to inform clinical practices and policy decisions. Ensuring sound methodology is critical for making valid inferences from these studies.

METHODS

The Biologics and Biosimilars Collective Intelligence Consortium (BBCIC) convened a workgroup consisting of academic researchers, industry scientists, and practicing clinicians to establish best practice recommendations for the conduct of noninterventional studies of biosimilar and reference biologic switching. The workgroup members participated in eight teleconferences between August 2017 and February 2018 to discuss specific topics and build consensus.

RESULTS

This report provides workgroup recommendations covering five main considerations relating to noninterventional studies describing reference biologic to biosimilar switching and comparing reference biologic to biosimilars for safety and effectiveness in the presence of switching at treatment initiation and during follow-up: (a) selecting appropriate data sources from a range of available options including insurance claims, electronic health records, and registries; (b) study designs; (c) outcomes of interest including health care utilization and clinical endpoints; (d) analytic approaches including propensity scores, disease risk scores, and instrumental variables; and (e) special considerations including avoiding designs that ignore history of biologic use, avoiding immortal time bias, exposure misclassification, and accounting for postindex switching.

CONCLUSION

Recommendations provided in this report provide a framework that may be helpful in designing and critically evaluating postapproval noninterventional studies involving reference biologic to biosimilar switching.

A threshold trajectory was revealed by isolating the effects of hemoglobin rate of rise in anemia of chronic kidney disease

BACKGROUND

To assess cardiovascular risk among various hemoglobin (Hb) rates of rise (RoR) in chronic kidney disease (CKD) patients with anemia who have initiated therapy with erythropoiesis stimulating agents (ESAs).

METHODS

Observational cohort of CKD patients initiating ESA therapy from the Centricity® database, 1990-2011. Proportional hazards models tested the hypothesis that a slower Hb RoR (0 < g/dl/month ⩽ 0.125) is associated with a lower cardiovascular (CV) incidence [composite of fatal/nonfatal myocardial infarction (MI) and stroke] compared with faster RoR (0.125 < g/dl/month ⩽ 2.0, and >2.0 g/dl/month).

RESULTS

A total of 9220 patients receiving ESAs were followed for an average of 3.1 years. Slow (group B) RoR versus medium (group C') and fast (group D') RoR in Hb, throughout all Hb milestones, was associated with lower risk of the composite endpoint [B (slow) versus D' (fast) [hazard ratio (HR) = 0.20 (0.11, 0.39), p < 0.0001]; B versus C' (medium) [HR = 0.34 (0.19, 0.62), p = 0.0004], and C' versus D' [HR = 0.60 (0.42, 0.85), p = 0.005]]. Within achieved Hb milestones, HRs were: B versus D' at milestone ⩾ 14.1 g/dl [HR = 0.17 (0.05, 0.56); p = 0.004] and at milestone 12.6-14.0 [HR = 0.18 (0.07, 0.46), p = 0.0004].

CONCLUSION

Rapid Hb rise is associated with adverse CV outcomes, with markedly lower risk for rates below a threshold trajectory of 0.125 g/dl/month, even with complete correction.

Epoetin Alfa and Outcomes in Dialysis amid Regulatory and Payment Reform

Erythropoiesis-stimulating agents (ESAs) are commonly used to treat anemia in patients with CKD, including those receiving dialysis, although clinical trials have identified risks associated with ESA use. We evaluated the effects of changes in dialysis payment policies and product labeling instituted in 2011 on mortality and major cardiovascular events across the United States dialysis population in an open cohort study of patients on dialysis from January 1, 2005, through December 31, 2012, with Medicare as primary payer. We compared observed rates of death and major cardiovascular events in 2011 and 2012 with expected rates calculated on the basis of rates in 2005-2010, accounting for differences in patient characteristics and influenza virulence. An abrupt decline in erythropoietin dosing and hemoglobin concentration began in late 2010. Observed rates of all-cause mortality, cardiovascular mortality, and myocardial infarction in 2011 and 2012 were consistent with expected rates. During 2012, observed rates of stroke, venous thromboembolic disease (VTE), and heart failure were lower than expected (absolute deviation from trend per 100 patient-years [95% confidence interval]: -0.24 [-0.08 to -0.37] for stroke, -2.43 [-1.35 to -3.70] for VTE, and -0.77 [-0.28 to -1.27] for heart failure), although non-ESA-related changes in practice and Medicare payment penalties for rehospitalization may have confounded the results. This initial evidence suggests that action taken to mitigate risks associated with ESA use and changes in payment policy did not result in a relative increase in death or major cardiovascular events and may reflect improvements in stroke, VTE, and heart failure.

The greatly misunderstood erythropoietin resistance index and the case for a new responsiveness measure

Introduction The optimal use of erythropoiesis stimulating agents (ESAs) to treat anemia in end stage renal disease remains controversial due to reported associations with adverse events. In analyzing these associations, studies often utilize ESA resistance indices (ERIs), to characterize a patient's response to ESA. In this study, we examine whether ERI is an adequate measure of ESA resistance. Methods We used retrospective data from a nonconcurrent cohort study of incident hemodialysis patients in the United States (n = 9386). ERI is defined as average weekly erythropoietin (EPO) dose per kg body weight (wt) per average hemoglobin (Hgb), over a 3-month period (ERI = (EPO/wt)/Hgb). Linear regression was used to demonstrate the relationship between ERI and weight-adjusted EPO. The coefficient of variation was used to compare the variability of Hgb with that of weight-adjusted EPO to explain this relationship. This analysis was done for each quarter during the first year of dialysis. Findings ERI is strongly linearly related with weight-adjusted EPO dose in each of the four quarters by the equation ERI = 0.0899*(EPO/wt) (range of R(2)  = 0.97-0.98) and weakly linearly related to 1/Hgb (range of R(2)  = 0.06-0.16). These correlations hold independent of age, sex, hgb level, ERI level, and epo-naïve stratifications. Discussion ERI is strongly linearly related to weight-adjusted (and nonweight-adjusted) EPO dose by a "universal," not patient-specific formula, and thus is a surrogate of EPO dose. Therefore, associations between ERI and clinical outcomes are associations between a confounded EPO dose and those outcomes.

Variation between hospitals in inpatient admission practices for self-harm patients and its impact on repeat presentation

PURPOSE

Self-harm patient management varies markedly between hospitals, with fourfold differences in the proportion of patients who are admitted to a medical or psychiatric inpatient bed. The current study aimed to investigate whether differences in admission practices are associated with patient outcomes (repeat self-harm) while accounting for differences in patient case mix.

METHODS

Data came from the National Self-Harm Registry Ireland. A prospective cohort of 43,595 self-harm patients presenting to hospital between 2007 and 2012 were included. As well as conventional regression analysis, instrumental variable (IV) methods utilising between hospital differences in rates of hospital admission were used in an attempt to gain unbiased estimates of the association of admission with risk of repeat self-harm.

RESULTS

The proportion of self-harm patients admitted to a medical bed varied from 10 to 74 % between hospitals. Conventional regression and IV analysis suggested medical admission was not associated with risk of repeat self-harm. Psychiatric inpatient admission was associated with an increased risk of repeat self-harm in both conventional and IV analyses. This increased risk persisted in analyses stratified by gender and when restricted to self-poisoning patients only.

CONCLUSIONS

No strong evidence was found to suggest medical admission reduces the risk of repeat self-harm. Models of health service provision that encourage prompt mental health assessment in the emergency department and avoid unnecessary medical admission of self-harm patients appear warranted. Psychiatric inpatient admission may be associated with a heightened risk of repeat self-harm in some patients, but these findings could be biased by residual confounding and require replication.

Erythropoiesis-stimulating agent resistance and mortality in hemodialysis and peritoneal dialysis patients

Background

Responsiveness to erythropoiesis-stimulating agents (ESAs) varies widely among dialysis patients. ESA resistance has been associated with mortality in hemodialysis (HD) patients, but in peritoneal dialysis (PD) patients data is limited. Therefore we assessed the relation between ESA resistance in both HD and PD patients.

Methods

NECOSAD is a Dutch multi-center prospective cohort study of incident dialysis patients who started dialysis between January 1997 and January 2007. ESA resistance was defined as hemoglobin level < 11 g/dL with an above median ESA dose (i.e. 8,000 units/week in HD and 4,000 units/week in PD patients). Unadjusted and adjusted Cox regression analysis for all-cause 5-year mortality was performed for HD and PD patients separately.

Results

1013 HD and 461 PD patients were included in the analysis. ESA resistant HD patients had an adjusted hazard ratio of 1.37 (95% CI 1.04-1.80) and ESA resistant PD patients had an adjusted hazard ratio of 2.41 (1.27-4.57) as compared to patients with a good response.

Conclusions

ESA resistance, as defined by categories of ESA and Hb, is associated with increased mortality in both HD and PD patients. The effect of ESA resistance, ESA dose and hemoglobin are closely related and the exact mechanism remains unclear. Our results strengthen the need to investigate and treat causes of ESA resistance not only in HD, but also in PD patients.

Anaemia management and mortality risk in chronic kidney disease

Renal anaemia is a frequent complication in patients with chronic kidney disease (CKD). Severe anaemia (haemoglobin <90 g/l) is associated with increased risks of mortality and cardiac complications, such as left ventricular hypertrophy and cardiovascular disease, and impaired quality of life. Randomized controlled trials have tested the hypothesis that increasing haemoglobin level using erythropoiesis-stimulating agents (ESAs) lowers these risks and improves quality of life. Use of ESAs to normalize haemoglobin levels (to ≥130 g/l) versus the partial correction of anaemia (to haemoglobin levels of 90-110 g/l) has repeatedly been shown to have no cardiac benefit and to be associated with no incremental improvement in outcomes and quality of life (except fatigue), but has been shown to be associated with an increased risk of cardiovascular events and death. Use of more-intense iron dosing has been proposed in order to reduce ESA dosing but liberal intravenous iron therapy is also associated with complications, and its long-term safety has not yet been adequately investigated. For patients with CKD on dialysis, US medication labels recommend administering ESAs at doses sufficient to avoid transfusions, whereas European and Canadian labels recommend targeting haemoglobin levels of 100-120 g/l and 110-120 g/l, respectively. Treatment of anaemia to haemoglobin levels of 90-110 g/l in patients with CKD accomplishes what we want--a reduced need for transfusions and possible reductions in fatigue, while avoiding high doses of ESA or iron in order to achieve a specific haemoglobin goal.

Blood pressure levels and mortality risk among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study

KDOQI practice guidelines recommend predialysis blood pressure <140/90 mm Hg; however, most prior studies had found elevated mortality with low, not high, systolic blood pressure. This is possibly due to unmeasured confounders affecting systolic blood pressure and mortality. To lessen this bias, we analyzed 24,525 patients by Cox regression models adjusted for patient and facility characteristics. Compared with predialysis systolic blood pressure of 130-159 mm Hg, mortality was 13% higher in facilities with 20% more patients at systolic blood pressure of 110-129 mm Hg and 16% higher in facilities with 20% more patients at systolic blood pressure of ≥160 mm Hg. For patient-level systolic blood pressure, mortality was elevated at low (<130 mm Hg), not high (≥180 mm Hg), systolic blood pressure. For predialysis diastolic blood pressure, mortality was lowest at 60-99 mm Hg, a wide range implying less chance to improve outcomes. Higher mortality at systolic blood pressure of <130 mm Hg is consistent with prior studies and may be due to excessive blood pressure lowering during dialysis. The lowest risk facility systolic blood pressure of 130-159 mm Hg indicates this range may be optimal, but may have been influenced by unmeasured facility practices. While additional study is needed, our findings contrast with KDOQI blood pressure targets, and provide guidance on optimal blood pressure range in the absence of definitive clinical trial data.

Confounding and control of confounding in nonexperimental studies of medications in patients with CKD

Confounding is an important source of bias in nonexperimental studies, arising when the effect of an exposure on the occurrence of an outcome is distorted by the effect of some other factor. In nonexperimental studies of patients with CKD or who are on chronic dialysis, confounding is a significant concern owing to the high burden of comorbid disease, extent of required clinical management, and high frequency of adverse clinical events in this patient population. Confounding can be addressed in both the design stage (restriction, accurate measurement of confounders) and analysis stage (stratification, multivariable adjustment, propensity scores, marginal structural models, instrumental variable) of a study. Time-dependent confounding and confounding by indication are 2 special cases of confounding that can arise in studies of treatment effects and may require more sophisticated analytic techniques to adequately address. The availability and expanded use of large health care databases have ensured greater precision and have now placed the focus on validity. Addressing the major threats to validity, such as confounding, should be a first-order concern.

Erythropoiesis-stimulating agent responsiveness and mortality in hemodialysis patients: results from a cohort study from the dialysis registry in Japan

BACKGROUND

Patient responsiveness to erythropoiesis-stimulating agents (ESAs), notoriously difficult to measure, has attracted attention for its association with mortality. We defined categories of ESA responsiveness and attempted to clarify their association with mortality.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Data from Japan's dialysis registry (2005-2006), including 95,460 adult hemodialysis patients who received ESAs.

PREDICTOR

We defined 6 categories of ESA responsiveness based on a combination of ESA dosage (low [<6,000 U/wk] or high [≥6,000 U/wk]) and hemoglobin level (low [<10 g/dL], medium [10-11.9 g/dL], or high [≥12 g/dL]), with medium hemoglobin level and low-dose ESA therapy as the reference category.

OUTCOMES

All-cause and cardiovascular mortality during 1-year follow-up.

MEASUREMENTS

HRs were estimated using a Cox model for the association between responsiveness categories and mortality, adjusting for potential confounders such as age, sex, postdialysis weight, dialysis duration, comorbid conditions, serum albumin level, and transferrin saturation.

RESULTS

Median ESA dosage (4,500-5,999 U/wk) was used as a cutoff point, and mean hemoglobin level was 10.1 g/dL in our cohort. Of 95,460 patients during follow-up, 7,205 (7.5%) died of all causes, including 5,586 (5.9%) cardiovascular deaths. Low hemoglobin levels and high-dose ESA therapy were both associated with all-cause mortality (adjusted HRs, 1.18 [95% CI, 1.09-1.27] for low hemoglobin level with low-dose ESA and 1.44 [95% CI, 1.34-1.55] for medium hemoglobin level with high-dose ESA). Adjusted HRs for high-dose ESA with low hemoglobin level (hyporesponsiveness) were 1.94 (95% CI, 1.82-2.07) for all-cause and 2.02 (95% CI, 1.88-2.17) for cardiovascular mortality. We also noted the interaction between ESA dosage and hemoglobin level on all-cause mortality (likelihood ratio test, P = 0.002).

LIMITATIONS

Potential residual confounding from unmeasured factors and single measurement of predictors.

CONCLUSIONS

Mortality can be affected by ESA responsiveness, which may include independent and interactive effects of ESA dose and hemoglobin level. Responsiveness category has prognostic importance and clinical relevance in anemia management.

High doses of epoetin do not lower mortality and cardiovascular risk among elderly hemodialysis patients with diabetes

A randomized trial had suggested that high doses of erythropoiesis-stimulating agents (ESAs) might increase the risk of cardiovascular outcomes in predialysis diabetic patients. To evaluate this risk in diabetic patients receiving dialysis, we used data from 35,593 elderly Medicare patients on hemodialysis in the US Renal Data System of whom 19,034 were diabetic. A pooled logistic model was used to estimate the monthly probability of mortality and a composite cardiovascular end point. Inverse probability weighting was used to adjust for measured time-dependent confounding by indication, estimated separately for diabetic and non-diabetic cohorts. The adjusted 9-month mortality risk, significantly different between an ESA dose of 45,000 and 15,000 U/week, was 13% among diabetics and 5% among non-diabetics. In diabetic patients, the hazard ratio (HR) for more than 40,000 U/week was 1.32 for all-cause mortality and 1.26 for a composite end point of death and cardiovascular events compared with patients receiving 20,000 to 30,000 U/week. The corresponding HRs in non-diabetic patients were 1.06 and 1.10, respectively. A smaller effect of dose was found in non-diabetic patients. Thus, higher ESA doses, which are often necessary to achieve high hemoglobin levels, are not beneficial, and possibly harmful, to diabetic patients receiving dialysis. Our findings support a Food and Drug Administration advisory recommending that the lowest possible ESA dose be used to treat hemodialysis patients.

Association of mean weekly epoetin alfa dose with mortality risk in a retrospective cohort study of Medicare hemodialysis patients

BACKGROUND/AIMS

Randomized trials of hemoglobin targeting in chronic kidney disease suggest that erythropoiesis-stimulating agent (ESA) dosing increases mortality risk, but dosing intensity is confounded by hemoglobin concentration. Appropriately designed observational studies are needed to clarify the association of ESA dosing with mortality risk.

METHODS

Using Medicare claims, we conducted a retrospective cohort study of mortality risk associated with epoetin alfa (EPO) dosing in prevalent hemodialysis patients (n = 137,918), 2000-2004. We used marginal structural modeling to account for time-varying confounding attributable to recent history of blood transfusion and catheter insertion for vascular access, hemoglobin, hospital admission and days, and intravenous iron dosing. We stratified mortality analyses according to hemoglobin level (<10, 10-10.9, 11-11.9, and ≥12 g/dl).

RESULTS

With adjustment for serial correlation in EPO dosing, hemoglobin, hospital admission and days, and intravenous iron administration were the strongest predictors of outpatient EPO dosing. With hemoglobin <10 g/dl, mean weekly EPO dose in a 3-month period was negatively associated with subsequent mortality risk. With hemoglobin 10-10.9 and 11-11.9 g/dl, EPO dose and mortality risk were associated in a U-shaped form. With hemoglobin ≥12 g/dl, mean weekly EPO dose >20,000 IU was positively associated with mortality risk.

CONCLUSIONS

ESA dosing may be directly associated with risk of death, but the nature of the association likely varies according to hemoglobin concentration. Small doses with hemoglobin ≤12 g/dl and large doses with hemoglobin ≥10 g/dl may both be associated with poor outcomes.

Quality of original and biosimilar epoetin products

PURPOSE

To compare the quality of therapeutic erythropoietin (EPO) products, including two biosimilars, with respect to content, aggregation, isoform profile and potency.

METHODS

Two original products, Eprex (epoetin alpha) and Dynepo (epoetin delta), and two biosimilar products, Binocrit (epoetin alpha) and Retacrit (epoetin zeta), were compared using (1) high performance size exclusion chromatography, (2) ELISA, (3) SDS-PAGE, (4) capillary zone electrophoresis and (5) in-vivo potency.

RESULTS

Tested EPO products differed in content, isoform composition, and potency.

CONCLUSION

Of the tested products, the biosimilars have the same or even better quality as the originals. Especially, the potency of originals may significantly differ from the value on the label.

Instrumental variable methods in comparative safety and effectiveness research

Instrumental variable (IV) methods have been proposed as a potential approach to the common problem of uncontrolled confounding in comparative studies of medical interventions, but IV methods are unfamiliar to many researchers. The goal of this article is to provide a non-technical, practical introduction to IV methods for comparative safety and effectiveness research. We outline the principles and basic assumptions necessary for valid IV estimation, discuss how to interpret the results of an IV study, provide a review of instruments that have been used in comparative effectiveness research, and suggest some minimal reporting standards for an IV analysis. Finally, we offer our perspective of the role of IV estimation vis-à-vis more traditional approaches based on statistical modeling of the exposure or outcome. We anticipate that IV methods will be often underpowered for drug safety studies of very rare outcomes, but may be potentially useful in studies of intended effects where uncontrolled confounding may be substantial.