This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Safety & Efficacy of Peginesatide for Treatment of Anemia in Participants on Dialysis Not Receiving an ESA (NCT00680043), a randomized phase 2 study. The primary outcome is Mean Change in Hemoglobin Between Baseline and the Evaluation Period.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00680043 |
| Phase | Phase 2 |
| Condition | Anemia, Chronic Renal Failure, Chronic Kidney Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 114 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Affymax |
| Results posted | Yes |
2. Clinical Question
Population
Participants had anemia and chronic renal failure, also described in the record as chronic kidney disease. They were undergoing hemodialysis and were not receiving erythropoiesis-stimulating agent treatment. The registry record identifies the primary analysis population as the Full Analysis Population. Further eligibility details are not reported in the registry record.
Intervention
Peginesatide was studied at doses of 0.04 mg/kg and 0.08 mg/kg. The record identifies both as drug interventions. Further details about how treatment was administered are not reported in the registry record.
Comparator
The active comparator was epoetin alfa. The study had three arms: peginesatide 0.04 mg/kg, peginesatide 0.08 mg/kg, and epoetin alfa. The allocation ratio and further treatment details are not reported in the registry record.
Primary question
The primary endpoint asks how mean hemoglobin changed from baseline to the evaluation period. The evaluation period was Study Weeks 21 through 28. The registry record describes this endpoint but does not report the arm-level values or a comparison result.
In statistical terms, the question is whether the observed mean change in hemoglobin differed among the assigned treatment groups over the stated assessment period. The study was randomized and used an active comparator, so its design was intended to compare assigned treatments rather than simply describe a single group. However, the registry record does not report the primary outcome estimates, measures of uncertainty, or a statistical test for this question. It therefore does not permit a quantitative conclusion about the relative hemoglobin changes.
3. Trial Design
This was a Phase 2, randomized, active-controlled, open-label, multicenter, parallel-group study. It enrolled 114 participants. The registry record lists three groups: peginesatide 0.04 mg/kg, peginesatide 0.08 mg/kg, and epoetin alfa. Randomization means participants were assigned to treatment groups by chance; the allocation ratio and the specific randomization procedure are not reported in the registry record.
The study focused on anemia in people with chronic renal failure who were undergoing hemodialysis and were not receiving erythropoiesis-stimulating agent treatment. Its stated purpose was to evaluate the safety and efficacy of peginesatide for treatment of anemia in this population. The primary endpoint was mean change in hemoglobin between baseline and the evaluation period, with the latter defined as Study Weeks 21 through 28. The registry record also lists outcomes concerning red blood cell or whole blood transfusions and hemoglobin response during the correction and evaluation periods.
Open-label means the study was not masked: treatment assignment was not concealed from participants and study personnel in the design described by the record. As a general consideration, awareness of assignment can influence care decisions, reporting, or assessment, depending on the outcome and study procedures. The record does not describe safeguards or procedures addressing those possibilities.
The study was sponsored by Affymax. Its status is listed as completed, with a start date of 2008-06 and primary completion in 2009-08. The registry record does not report details of the protocol, the allocation ratio, or the planned statistical analysis. It also does not report whether there were protocol amendments or interim analyses.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Peginesatide 0.04 mg/kg | Peginesatide 0.08 mg/kg | Epoetin Alfa |
|---|---|---|---|
| STARTED | 39 | 37 | 38 |
| COMPLETED | 37 | 36 | 34 |
| NOT COMPLETED | 2 | 1 | 4 |
Reasons for not completing this period:
| Reason | Peginesatide 0.04 mg/kg | Peginesatide 0.08 mg/kg | Epoetin Alfa |
|---|---|---|---|
| Withdrawal by Subject | 1 | 0 | 0 |
| Patient Not Compliant With Study Reqs. | 0 | 1 | 0 |
| Renal Transplant | 1 | 0 | 4 |
Analysis population for the primary outcome, as defined in the registry: Full Analysis Population
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Peginesatide 0.04 mg/kg | Peginesatide 0.08 mg/kg | Epoetin Alfa | Total |
|---|---|---|---|---|---|
| Participants analysed | 39 | 37 | 38 | 114 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 37 | 31 | 30 | 98 |
| Age, Categorical: >=65 years | Participants | 2 | 6 | 8 | 16 |
| Age Continuous | years | 48.8 (SD 11.71) | 48.8 (SD 13.55) | 51.4 (SD 14.16) | 49.7 (SD 13.10) |
| Sex: Female, Male: Female | Participants | 12 | 14 | 19 | 45 |
| Sex: Female, Male: Male | Participants | 27 | 23 | 19 | 69 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Change in Hemoglobin Between Baseline and the Evaluation Period, measured over Baseline and Weeks 21-28.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | g/dL |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the mean change in hemoglobin between baseline and the evaluation period, measured in g/dL. Hemoglobin is a continuous measurement, so the endpoint summarizes the average change across participants rather than counting how many participants fall into a response category. The registry record identifies the Full Analysis Population for this endpoint and describes the statistic as a mean with standard deviation.
Baseline is defined as the mean of the two most recent hemoglobin values taken before randomization plus the value obtained on the day of randomization before Dose 1. The record then defines each participant’s evaluation-period hemoglobin as the mean of available values during Study Weeks 21 through 28. The endpoint compares these baseline and evaluation-period summaries.
As a general statistical point, a continuous endpoint can preserve information across the range of observed measurements. A group mean provides a concise summary, while a standard deviation describes how dispersed individual measurements are around that mean. Neither summary alone shows the full distribution or the precision of a treatment-group comparison.
The registry record does not report the mean changes, standard deviations, confidence intervals, or a test of the primary comparison. It therefore does not establish the size or precision of any observed difference between groups.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a primary endpoint but does not report its results. No group-specific mean change in hemoglobin, standard deviation, confidence interval, or statistical test is reported in the registry record. Consequently, the size and precision of the primary comparison cannot be assessed from this record. A missing result is not evidence that groups were alike, and it is not evidence that a difference was present.
The outcome was defined using a baseline summary and average hemoglobin values during Study Weeks 21 through 28. That definition establishes what the endpoint was intended to summarize, but it does not reveal the observed changes. Without the group estimates and an appropriate comparison, the direction and magnitude of the results remain unknown. The record also does not report the number of participants contributing evaluable hemoglobin measurements at each assessment.
The record lists two other outcome topics: the proportion of participants receiving red blood cell or whole blood transfusions during the correction and evaluation periods, and the proportion achieving hemoglobin response during those periods. It does not provide results for these outcomes in the information recorded. Their inclusion in the outcome list should not be taken as evidence about their observed frequency or about differences among treatment groups.
Safety data are reported separately. The record lists serious adverse-event counts of 6 among 39 at risk for peginesatide 0.04 mg/kg, 8 among 37 at risk for peginesatide 0.08 mg/kg, and 4 among 38 at risk for epoetin alfa. It also lists other adverse-event counts of 21 among 39, 26 among 37, and 27 among 38, respectively. These counts describe the registry’s adverse-event summaries; they do not supply a comparative statistical analysis or establish causation. The record does not report deaths for these groups.
As a general statistical principle, estimates are most informative when paired with uncertainty measures and clear information about the analyzed population. Those details are not reported for the primary endpoint in the registry record. The completed status of the study does not fill that gap: completion describes study status, not whether results are available in this record.
9. Statistical Methods Explained
The registry record identifies a continuous primary endpoint: mean change in hemoglobin from baseline to the evaluation period. It specifies the mean as the summary measure and standard deviation as the measure of dispersion. It does not report the statistical test, model, confidence interval method, or adjustment strategy used for the primary comparison. The following explanations describe general statistical concepts, not methods confirmed to have been used in this trial.
What does a mean change summarize?
In general, a mean change combines individual changes into a single average. It can be useful when the scientific question concerns average change in a continuous measure. The average does not show whether all participants changed by similar amounts: participants can have quite different individual values while producing the same group mean. The standard deviation describes the spread of observed measurements around a mean, but it is not the same as the uncertainty in the mean or in a difference between group means.
The endpoint definition uses a summary at baseline and a summary over an evaluation window. As a general matter, averaging measurements can reduce the influence of short-term fluctuation, but it also means the endpoint represents an average over the specified window rather than a single measurement at one visit. The registry record does not report how many measurements were available for each participant or how the analysis handled participants with incomplete measurements.
What does randomization contribute?
In general, random assignment helps make treatment groups comparable at the time of assignment by distributing measured and unmeasured participant characteristics through chance. It does not guarantee that the groups will be identical, particularly in a study of limited size. The record identifies the study as randomized but does not report the sequence-generation method, any stratification factors, the allocation ratio, or procedures for concealing assignment before randomization. Those details are not reported in the registry record.
Randomization supports comparison of assigned groups, but the interpretation depends on how the analysis treats participants after assignment. For example, analyses that retain participants in their assigned groups answer a different practical question from analyses restricted to participants who completed treatment. The registry record names the Full Analysis Population for the primary endpoint but does not define its membership or explain how departures from assigned treatment were handled.
How should uncertainty be understood?
In general, a confidence interval gives a range of values compatible with the data under the assumptions of the statistical method. Its width reflects uncertainty: a narrower interval indicates greater precision, while a wider interval indicates less precision. A confidence interval for a treatment contrast would help readers judge both the plausible size and direction of a difference. The primary endpoint’s confidence intervals are not reported in the registry record.
A p-value, when used, measures how unusual data at least as incompatible with a specified null hypothesis would be under the assumptions of the test. It does not measure the probability that a treatment is effective, nor does it describe the size or clinical importance of a difference. The primary endpoint’s p-value and test are not reported in the registry record. A result should not be characterized as statistically significant or nonsignificant without a reported analysis.
Why does the analysis population matter?
In general, an analysis population defines which randomized participants contribute to an estimate. Different definitions can lead to different estimates, especially when participants discontinue treatment, have missing measurements, or do not follow the assigned treatment. The record’s reference to the Full Analysis Population is useful as a label, but its operational definition, the number analyzed in each arm, and the handling of missing measurements are not reported in the registry record.
Missing outcome data can affect both precision and validity. If measurements are absent for reasons related to participants’ health or their observed outcomes, analyzing only available values may produce a biased estimate. Statistical approaches can make assumptions about missingness, but those assumptions need to be stated and assessed. The registry record does not report a missing-data method, sensitivity analyses, or the amount and pattern of missing primary outcome data.
What does an open-label design imply?
As a general consideration, lack of masking can influence decisions and assessments when people know treatment assignment. A laboratory measurement may be less subjective than a judgment-based outcome, but open-label status can still matter through treatment changes, follow-up, or availability of measurements. The record states that masking was none; it does not describe whether laboratory assessment or outcome processing used any independent safeguards.
Finally, the registry record does not report the primary statistical plan, model assumptions, multiplicity procedures, interim analyses, or sample-size justification. Those details should not be inferred from the design label or from the fact that the study enrolled 114 participants. Any sample-size figures elsewhere intended as planning illustrations based on an observed effect would not be observed power, and they would not substitute for the trial’s own design rationale. No such calculated sample-size result is reported in this record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary endpoint and additional outcome topics, but it does not report a multiplicity strategy. Multiplicity arises when several outcomes, treatment comparisons, time periods, or analyses are examined: the more opportunities there are to identify a result, the greater the general risk of a chance finding if each is interpreted separately. This is a general statistical consideration, not a statement that a particular procedure was or was not used in the trial. The statistical plan and any adjustment for multiple comparisons are not reported in the registry record.
The record identifies the Full Analysis Population for the primary endpoint. It does not provide a detailed definition of that population, the number included in each arm, or the number contributing data to the primary analysis. A population label alone does not establish how participants with missing visits, treatment discontinuation, or protocol deviations were handled.
Baseline and evaluation-period measurement definitions are described, but missing-data procedures are not. The record does not report how missing hemoglobin values were handled when forming participant averages, whether imputation was used, or whether sensitivity analyses assessed assumptions about missingness. These omissions limit assessment of how robust any primary estimate would be to incomplete follow-up.
Likewise, the record does not report an interim-analysis plan, stopping rules, or a sample-size justification. Their absence from this record should not be read as evidence that the study did or did not use such procedures. The registry record also does not report the planned statistical model or whether covariates were included.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Peginesatide 0.04 mg/kg | 6 | 39 | 15.4% |
| Peginesatide 0.08 mg/kg | 8 | 37 | 21.6% |
| Epoetin Alfa | 4 | 38 | 10.5% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Peginesatide 0.04 mg/kg | 21 of 39 |
| Peginesatide 0.08 mg/kg | 26 of 37 |
| Epoetin Alfa | 27 of 38 |
Most frequent serious adverse event terms
| Event term | Organ system | Peginesatide 0.04 mg/kg | Peginesatide 0.08 mg/kg | Epoetin Alfa |
|---|---|---|---|---|
| Arteriovenous fistula thrombosis | Injury, poisoning and procedural complications | 3 of 39 | 1 of 37 | 2 of 38 |
| Vitreous haemorrhage | Eye disorders | 2 of 39 | 0 of 37 | 0 of 38 |
| Haemorrhagic anaemia | Blood and lymphatic system disorders | 0 of 39 | 1 of 37 | 0 of 38 |
| Pancreatitis chronic | Gastrointestinal disorders | 1 of 39 | 0 of 37 | 0 of 38 |
| Pyrexia | General disorders | 0 of 39 | 0 of 37 | 1 of 38 |
| Appendicitis | Infections and infestations | 0 of 39 | 0 of 37 | 1 of 38 |
| Bronchitis | Infections and infestations | 1 of 39 | 0 of 37 | 0 of 38 |
| Hepatitis C | Infections and infestations | 1 of 39 | 0 of 37 | 0 of 38 |
| Pneumonia | Infections and infestations | 0 of 39 | 1 of 37 | 0 of 38 |
| Pyelonephritis | Infections and infestations | 1 of 39 | 0 of 37 | 0 of 38 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Peginesatide 0.04 mg/kg | Peginesatide 0.08 mg/kg | Epoetin Alfa |
|---|---|---|---|---|
| Procedural hypotension | Injury, poisoning and procedural complications | 9 of 39 | 4 of 37 | 8 of 38 |
| Hypertension | Vascular disorders | 9 of 39 | 6 of 37 | 5 of 38 |
| Muscle spasms | Musculoskeletal and connective tissue disorders | 3 of 39 | 7 of 37 | 6 of 38 |
| Procedural hypertension | Injury, poisoning and procedural complications | 5 of 39 | 4 of 37 | 6 of 38 |
| Headache | Nervous system disorders | 3 of 39 | 3 of 37 | 5 of 38 |
| Hyperparathyroidism secondary | Endocrine disorders | 3 of 39 | 1 of 37 | 4 of 38 |
| Hypotension | Vascular disorders | 1 of 39 | 1 of 37 | 6 of 38 |
| Respiratory tract infection | Infections and infestations | 3 of 39 | 3 of 37 | 1 of 38 |
| Osteoarthritis | Musculoskeletal and connective tissue disorders | 3 of 39 | 2 of 37 | 2 of 38 |
| Arteriovenous fistula operation | Surgical and medical procedures | 1 of 39 | 1 of 37 | 5 of 38 |
Serious events with the highest arm-level rate: arteriovenous fistula thrombosis (7.7%), vitreous haemorrhage (5.1%), haemorrhagic anaemia (2.7%), pneumonia (2.7%), sinusitis (2.7%).
The registry record lists participants at risk and participants affected for serious adverse events and for other adverse events. For serious adverse events, it reports 6 among 39 at risk in the peginesatide 0.04 mg/kg group, 8 among 37 in the peginesatide 0.08 mg/kg group, and 4 among 38 in the epoetin alfa group. For other adverse events, it reports 21 among 39, 26 among 37, and 27 among 38, respectively. These are descriptive counts, not results of a reported statistical comparison.
The record also lists serious adverse-event terms with percentages: arteriovenous fistula thrombosis, 7.7%; vitreous haemorrhage, 5.1%; haemorrhagic anaemia, 2.7%; pneumonia, 2.7%; sinusitis, 2.7%; and fluid overload, 2.7%. The record does not identify the treatment group associated with each listed term, so these terms cannot be assigned to a particular arm from the recorded information.
As a general point, adverse-event counts describe events recorded under a study’s definitions; they do not by themselves establish that treatment caused an event. The record does not report deaths for the listed groups. It also does not provide further detail about event severity definitions, exposure duration, statistical comparisons, or causal assessment. The counts should therefore be read as the registry’s descriptive safety information, not as a complete comparative safety analysis.
12. What the Result Does, and Does Not, Mean
The registry record identifies the study question, treatment groups, and primary endpoint, but it does not report the primary endpoint results. As a result, the record does not show how mean hemoglobin changed in any group or how the groups compared. It does not support a conclusion about the direction, magnitude, or precision of a primary treatment difference.
The same caution applies to the listed secondary outcomes. The registry record names transfusion and hemoglobin-response outcomes but does not report their results. An outcome listed in a registry is not itself evidence that a particular result occurred. The endpoint definitions and the observed findings are separate pieces of information.
The reported adverse-event counts allow a descriptive account of participants affected in each treatment group, and the record lists several serious adverse-event terms with percentages. These data do not, on their own, show whether differences between groups are meaningful or whether an event was caused by a treatment. The record does not report deaths for the groups and does not provide a comparative safety analysis.
In general, evidence about a treatment comparison requires estimates, uncertainty measures, and clear descriptions of the analysis population and methods. Those elements are not reported for the primary endpoint in the registry record. The study’s randomized design is relevant to how a complete analysis could be interpreted, but randomization cannot replace missing results.
The status listed as completed indicates that the study is recorded as completed; it does not imply that outcome findings are available in the registry record. The information recorded can establish what was planned or measured at a broad level and what adverse-event summaries were posted. It cannot establish treatment benefit, lack of benefit, or a definitive comparative safety profile.
13. Why This Trial Matters Statistically
This trial is statistically notable as a randomized comparison with an active comparator and two peginesatide dose groups in a defined dialysis population not receiving an erythropoiesis-stimulating agent. Its primary endpoint is a continuous measure summarized as mean change, which raises familiar questions about group estimates, variability, uncertainty, and missing measurements.
The registry record offers a clear operational description of the endpoint. It defines baseline using recent hemoglobin values and defines the evaluation-period value using available measurements during Study Weeks 21 through 28. That specificity helps identify what the outcome was intended to represent. However, without the observed means, standard deviations, and comparison estimates, readers cannot evaluate the treatment contrasts or their precision.
The study also illustrates why a design description and a result are not interchangeable. Randomization can strengthen the basis for comparing assigned groups, while open-label conduct may matter for processes surrounding treatment and assessment. Neither feature resolves the absence of reported primary findings. Likewise, naming an analysis population does not tell readers how missing measurements or treatment changes were handled.
For biostatisticians and clinical researchers, the record highlights the importance of complete reporting: outcome estimates, uncertainty intervals, analysis-population definitions, missing-data methods, and multiplicity plans all affect interpretation. Safety counts are useful descriptive information, but they are not a substitute for a comparative analysis and should be interpreted in light of the information available about event definitions and follow-up.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpreting efficacy is that the registry record does not report the primary endpoint results. Group-specific mean changes, standard deviations, confidence intervals, and statistical tests are not reported in the registry record. The listed secondary outcomes also lack reported results in the information recorded. Thus, the magnitude and precision of the treatment comparisons cannot be assessed.
The registry record names the Full Analysis Population but does not define it in detail or report how many participants were analyzed for the primary endpoint. It does not state how missing hemoglobin observations were handled, how participant-level averages were formed when values were incomplete, or whether sensitivity analyses were conducted. These details matter because incomplete follow-up can affect both precision and the validity of an estimate.
The record identifies the design as randomized and open-label but does not report the allocation ratio, randomization procedure, concealment process, or safeguards against assessment effects. The planned model, assumptions, covariate adjustment, multiplicity strategy, interim analyses, and sample-size justification are not reported in the registry record. These are unknowns, not evidence that any particular procedure was omitted from the study.
Safety reporting is also limited in the record. Counts and selected serious adverse-event terms are listed, but a comparative statistical analysis, further event definitions, exposure-adjusted summaries, and deaths are not reported. The treatment group for each listed serious event term is not specified in the recorded information. These limitations preclude a complete comparative evaluation of safety from this record alone.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety & Efficacy of Peginesatide for Treatment of Anemia in Participants on Dialysis Not Receiving an ESA — NCT00680043.
- Registry record last updated 2012-06-29; status last verified 2012-06.
- Results first posted 2012-05-30.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry record describes NCT00680043 as a completed, randomized, open-label, active-controlled, multicenter, parallel Phase 2 study sponsored by Affymax. It enrolled 114 participants with anemia and chronic renal failure who were undergoing hemodialysis and not receiving erythropoiesis-stimulating agent treatment. The groups received peginesatide 0.04 mg/kg, peginesatide 0.08 mg/kg, or epoetin alfa.
The primary endpoint was mean change in hemoglobin from baseline to Study Weeks 21 through 28, analyzed in the Full Analysis Population and summarized with a standard deviation. The endpoint definition is reported, but its results are not reported in the registry record. The record lists transfusion and hemoglobin-response outcomes without results in the information recorded.
Descriptive adverse-event counts and selected serious-event terms are reported. The record does not report deaths for the groups or a comparative safety analysis. Details of the statistical plan, missing-data handling, and multiplicity procedures are not reported in the registry record.