Peginesatide for Maintenance Treatment of Anemia in Participants on Hemodialysis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Peginesatide for Maintenance Treatment of Anemia in Participants on Hemodialysis (NCT00434330), a non-randomized phase 2 study. The primary outcome is Mean Hemoglobin Throughout the Trial and Mean Hemoglobin Change From Baseline Throughout the Trial..

2. Clinical Question

3. Trial Design

NCT00434330 is listed as a phase 2, open-label, multi-center, dose-finding study. Its official title describes safety, pharmacodynamics, and pharmacokinetics of peginesatide for maintenance treatment of anemia in hemodialysis patients previously treated with epoetin. The registry lists the study as completed, with enrollment of 91. The recorded start is 2006-12 and primary completion is 2008-04.

Allocation was non-randomized, masking was none, and the model was parallel. The registry identifies six cohorts: three with subcutaneous administration and three with intravenous administration. Cohort labels also distinguish Q4W scheduling and transition versus no-transition status. The record does not give the dose amounts, detailed allocation rules, or the reason for each cohort distinction. It therefore supports describing the structure, but not reconstructing the full dosing protocol.

The study purpose was to identify peginesatide dose ranges that maintained hemoglobin in people receiving dialysis whose hemoglobin values were stable on epoetin alfa or beta. Some participants had a one-week transition period, according to the definition of study start used for the baseline description; others did not. The exact procedure for transition and the allocation of participants to those approaches are not reported in the registry record.

Because assignment was not randomized and there is no described concurrent control arm, the cohorts should not be read as a like-for-like comparative trial. Differences between cohorts could reflect the cohort definitions or participant characteristics, in addition to the treatment features. The registry record does not report a prespecified statistical comparison among cohorts, and it contains no analysis records. The design is best understood as a dose-finding and descriptive assessment, rather than evidence from a randomized efficacy comparison.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Modified intent-to-treat (mITT) 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.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Mean Hemoglobin Throughout the Trial and Mean Hemoglobin Change From Baseline Throughout the Trial., measured over Baseline and Weeks 2-29.

The primary endpoint is described as mean hemoglobin throughout the trial and mean hemoglobin change from baseline throughout the trial. Hemoglobin is a continuous measure, recorded in g/dL. The timeframe is baseline and Weeks 2-29, and the listed summary statistic is the mean with standard deviation. The endpoint population is the modified intent-to-treat population.

Baseline was defined as the mean of the four most recent mid- or end-of-week predialysis hemoglobin values collected before study start. Study start differed according to transition status: it was the date of the first peginesatide injection for participants without a one-week transition, or the date epoetin treatment was first withheld for participants with a one-week transition. This definition matters because change from baseline depends on how the starting value and starting time are specified.

In general, repeated hemoglobin measurements can describe both the average level during follow-up and how that level changes relative to baseline. A mean summarizes the central level, while a standard deviation describes variability among measurements or participants, depending on the analysis unit. The registry record does not provide the numerical means, standard deviations, or change estimates. It also does not describe the specific method used to combine repeated measurements across the stated timeframe, so the endpoint label alone does not establish the exact analysis procedure.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins by separating the stated study question from the estimates needed to answer it. The stated question concerns maintaining hemoglobin, and the primary outcome is a continuous measure expressed in g/dL. The registry specifies mean hemoglobin and mean change from baseline across baseline and Weeks 2-29, with standard deviation as the dispersion measure. It does not provide numerical estimates for either measure, so no treatment effect or uncertainty can be described from the record.

What does a mean describe?

In general, a mean is a way to summarize the central level of a continuous measurement. For a repeated outcome such as hemoglobin, a mean may refer to measurements at a particular time, an average over time, or an average across participants; the interpretation depends on the analysis definition. The registry uses the phrase “throughout the trial,” but does not specify the calculation that turns repeated measurements into the reported mean. That detail is not reported in the registry record.

A standard deviation describes the spread of values around a mean. It is not the same as a confidence interval: a standard deviation describes variability in the data, while a confidence interval describes uncertainty in an estimated quantity under an analysis model. In general, confidence intervals help show which effect sizes are compatible with the data and analysis assumptions. No confidence intervals are reported for the primary endpoint, so the precision of the hemoglobin estimates cannot be judged.

Why does the baseline definition matter?

Change from baseline is calculated relative to a defined starting value. Here, baseline is the mean of the four most recent mid- or end-of-week predialysis hemoglobin values before study start. The registry also defines study start differently for participants with and without a one-week transition period. This makes the baseline specification part of the outcome definition, not merely a label. It establishes which prior measurements and which date anchor the subsequent change.

In general, using several pretreatment measurements can represent a participant’s starting level differently from relying on a single measurement. It can also make the meaning of change dependent on the timing and availability of those measurements. The record does not state how missing baseline values were handled or whether every participant contributed the same number of measurements. No additional assumptions about that process can be made from the endpoint description.

What can a parallel cohort structure establish?

The study is described as parallel and non-randomized, with no masking. Its six cohort labels distinguish subcutaneous or intravenous administration, Q4W scheduling, and transition status. In general, a parallel design follows participants in assigned groups rather than having each participant receive every approach. Randomization, when used, helps balance measured and unmeasured factors on average between groups. Because allocation is non-randomized, cohort differences may reflect participant selection as well as the treatment features. The record does not report the allocation procedure or covariate-adjusted comparisons.

Open-label means that masking was absent as recorded. In general, knowledge of treatment assignment can affect how subjective outcomes are assessed or how participants and staff behave. Hemoglobin is a laboratory measure, but the registry does not describe laboratory blinding or other safeguards. It would therefore be inappropriate to claim that open-label status had no effect, or that it did affect the results.

How should repeated measurements be analyzed?

Repeated observations from the same participant are generally correlated: measurements from one person are not independent in the same way as measurements from different people. General approaches can account for this correlation and for variation in measurement timing, but the choice of method influences estimates and uncertainty. The registry record does not identify a model, a covariance structure, a method for handling time, or a rule for selecting measurements. It reports no analysis records, so the actual statistical approach cannot be reconstructed.

Over-dispersion is a general concern when observed variability exceeds what a chosen statistical model expects. For a continuous repeated outcome, the broader issue is whether the model adequately represents the observed spread and correlation. If those features are not handled well, standard errors and confidence intervals may be misleading. This is a general methodological point, not a claim that over-dispersion occurred in this study; the record does not report enough analysis detail to assess it.

What do the planning illustrations mean?

The registry describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. Such illustrations are hypothetical planning scenarios: they describe participant numbers under specified assumptions, not what was observed in the trial and not the probability that the study’s findings are true. The registry does not report the actual calculated participant numbers in the registry record described for this analysis. The trial’s own sample-size justification is not reported in the registry record.

General sample-size calculations depend on the assumed effect, variability, significance level, allocation, and target power. Changing any assumption can change the planning requirement. A planning estimate is not observed power, and it cannot substitute for an estimate with an uncertainty interval. Because the numerical outcome results and calculated planning values are not reported in the registry record, the planning assumptions alone cannot establish whether the study was adequately sized for a particular comparison.

How should safety counts be interpreted statistically?

Safety summaries count participants affected by serious and other events within each cohort. Such counts describe how many participants were recorded as affected, using the listed at-risk group as context. In general, these counts do not account for differences in follow-up time unless exposure time is explicitly incorporated, and they do not show causation. The registry does not report exposure-adjusted rates, event-level timing, or a comparative safety model. The listed serious-event percentages also lack a stated denominator in the registry record, so their exact basis cannot be confirmed from the information available.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and identifies the hemoglobin endpoint as primary. It does not report an analysis record, and the number of analyses is listed as zero. The statistical plan, including any prespecified hierarchy among outcomes or formal adjustment for multiple testing, is not reported in the registry record. It is therefore not possible to determine whether the outcome measures were treated as separate confirmatory questions, whether additional time points were tested, or how multiplicity was addressed.

In general, testing many outcomes, time points, or subgroup comparisons can increase the chance of obtaining an apparently notable result by chance. Prespecified testing strategies or multiplicity adjustments can address that issue, but the registry does not describe such procedures. No conclusion about whether multiplicity was controlled or ignored is warranted from the available record.

The modified intent-to-treat population is named for the primary outcome, but its operational definition and size are not reported. The registry does not explain which participants were included or excluded from that population, whether analysis followed original cohort assignment, or how protocol deviations were handled.

Missing-data methods are also not reported. The record does not state how absent hemoglobin measurements, withdrawal, or incomplete follow-up were handled, nor whether the amount or pattern of missingness was summarized. In general, missing-data assumptions can affect repeated-measure estimates, especially if the likelihood of a missing value is related to the participant’s health or prior measurements. Without the methods and numerical results, the robustness of the endpoint to missing data cannot be assessed. The registry also does not report interim analyses or stopping rules.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: arteriovenous fistula thrombosis (13.3%), pyelonephritis chronic (12.5%), pneumonia (6.7%), sudden death (6.7%), anaemia (6.7%).

The safety record gives, for each cohort, the number at risk and the number affected by serious and other events. For serious events, the listed at-risk and affected counts are 15 and 2 for Cohort 1, 15 and 1 for Cohort 2, 16 and 3 for Cohort 3, 15 and 1 for Cohort 4, 15 and 3 for Cohort 5, and 15 and 2 for Cohort 6. For other events, the corresponding counts are 15 and 10, 15 and 8, 16 and 7, 15 and 8, 15 and 10, and 15 and 9. These are cohort-level counts, not evidence of a treatment effect.

The registry lists arteriovenous fistula thrombosis at 13.3%, chronic pyelonephritis at 12.5%, and pneumonia, sudden death, anaemia, and keratitis each at 6.7% among the top serious-event terms. The record does not state the denominator for these percentages or provide event-level timing and participant details. A listed term does not by itself establish that peginesatide caused the event. Death counts are not reported in the registry record; a null entry should not be read as a count of zero.

These safety figures are descriptive. The record does not provide a randomized control comparison, exposure-adjusted rates, or a statistical comparison of the cohorts. Differences in counts should therefore not be interpreted as evidence that one route or cohort was safer.

12. What the Result Does, and Does Not, Mean

The registry record establishes the purpose and broad design of a phase 2 dose-finding study: evaluating peginesatide dose ranges for maintenance of hemoglobin in people receiving hemodialysis who had been stable on epoetin. It also defines the intended endpoint, baseline construction, follow-up interval, and analysis population label. Those details help readers understand what was meant to be measured.

However, the numerical primary hemoglobin results are not reported in the registry record. Without means, changes from baseline, dispersion estimates, or confidence intervals, the amount of hemoglobin maintenance and its precision cannot be assessed. The missing numerical estimates do not imply either a positive or a negative result. They leave the primary outcome unanswered in the posted record.

The non-randomized, open-label structure also matters. Cohorts varied by route and transition features, and the record does not describe a concurrent control arm or randomized allocation. Consequently, even if cohort-level results were available, differences could not automatically be attributed to route or transition status. The registry does not report a formal comparative analysis to support such attribution.

The safety information provides counts and selected serious-event terms, but not a causal assessment. The absence of reported death counts is not evidence that no deaths occurred. Nor do the listed event percentages, without a stated denominator and comparative analysis, establish differences in risk.

In general, a useful treatment interpretation requires estimates, uncertainty, and a clear analysis population and method, considered alongside design limitations. The registry record gives some of the design and endpoint definitions but omits key outcome and analysis details. It therefore supports describing the research question and the structure of the study, not a conclusion about treatment benefit, lack of benefit, or comparative safety.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a dose-finding question differs from a randomized treatment comparison. The study considered peginesatide in participants on hemodialysis whose hemoglobin values were stable on epoetin, and its cohorts varied in route and transition status. The stated aim was to identify dose ranges associated with maintaining hemoglobin. That objective requires careful attention to the endpoint definition and to how repeated measurements are summarized.

The baseline definition is particularly important for a change outcome. It uses the mean of four recent predialysis measurements, while the study-start date depends on transition status. Those choices determine the reference point for change and influence how the outcome is interpreted. The registry gives these definitions, which is useful, but does not provide the numerical estimates or the analysis method needed to judge the observed pattern.

The trial also illustrates why design and results must be read together. Non-randomized cohorts can describe experience across approaches, but cohort differences are not automatically causal contrasts. This limitation is relevant when interpreting any apparent differences by route or transition. The absence of reported analysis records makes it especially important not to infer a comparative result from the cohort structure alone.

Finally, the record separates the presence of a planned endpoint from availability of its results. It names the outcome and population, while numerical hemoglobin findings and analysis details are not reported. This distinction is broadly important in clinical statistics: design intent, observed estimates, uncertainty, and causal interpretation are separate parts of the evidence. The available safety counts likewise offer descriptive information without establishing attribution or comparative risk.

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.

Several trial-specific limitations constrain interpretation. First, allocation was non-randomized and masking was absent. The cohorts therefore do not constitute a randomized comparison, and the registry itself cautions that they are not a like-for-like control comparison. Differences among cohorts may reflect factors other than route or transition status. The record does not report an adjustment strategy that might address measured differences.

Second, numerical primary outcome estimates are not reported in the registry record. Mean hemoglobin, mean change from baseline, standard deviations, confidence intervals, and p-values are not available in the outcome information. The absence of these values prevents assessment of magnitude and precision. The record also contains no analysis entries, so the statistical method used for the repeated measurements is not described.

Third, although the modified intent-to-treat population is named, its definition and size are not reported. Rules for handling withdrawals, protocol deviations, incomplete follow-up, and missing hemoglobin values are also not reported. These omissions limit assessment of the population represented by any endpoint estimate and the sensitivity of findings to missing data.

Fourth, details needed to interpret the cohort structure are incomplete. The registry lists intravenous and subcutaneous routes, Q4W scheduling, and transition labels, but does not report dose amounts or detailed cohort assignment rules. The sample-size planning assumptions are stated, but the trial’s own sample-size justification is not reported in the registry record.

Finally, safety counts lack comparative analysis, and the denominators for the listed serious-event percentages are not reported. Death counts are not reported. These data can be described, but they do not establish causation or comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Peginesatide for Maintenance Treatment of Anemia in Participants on Hemodialysis — NCT00434330.
• Registry record last updated 2012-06-29; status last verified 2012-06.
• Results first posted 2012-05-28.
• 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.

18. Record Summary

NCT00434330 is a completed phase 2, open-label, non-randomized, parallel dose-finding study of peginesatide in hemodialysis participants previously treated with epoetin. Registry enrollment was 91; the recorded start was 2006-12 and primary completion was 2008-04. Six cohort labels distinguish intravenous or subcutaneous administration, Q4W scheduling, and transition status.

The primary outcome was mean hemoglobin and mean change from baseline in g/dL at baseline and Weeks 2-29, for the modified intent-to-treat population. Numerical primary outcome results and analysis records are not reported in the registry record. Safety counts are listed by cohort, along with selected serious-event terms, but deaths are not reported. The non-randomized design does not support treating the cohorts as a like-for-like control comparison.