Efficacy and Safety Study to Evaluate MT-6548 in Peritoneal Dialysis Subjects With Anemia Associated With Chronic Kidney Disease in Japan: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety Study to Evaluate MT-6548 in Peritoneal Dialysis Subjects With Anemia Associated With Chronic Kidney Disease in Japan (NCT03402386), a na phase 3 study. The primary outcome is Mean Hb Level of Week 20 and Week 24.

2. Clinical Question

The clinical question is therefore about hemoglobin measurements during MT-6548 treatment in this study population, rather than about a difference between MT-6548 and another treatment or control. Because there was only one group, any reported change or level would describe the observed course in that group. It would not, by itself, establish what would have happened over the same period without MT-6548 or under an alternative treatment.

The record’s primary endpoint description also specifies who was included in its analysis: subjects needed a hemoglobin measurement at least one visit after baseline. It does not state how many subjects met that condition, how baseline values were handled, or what model produced the least-squares mean. Those details matter when interpreting the endpoint and are not reported in the registry record.

3. Trial Design

This was a Phase III, open-label, single-group study of MT-6548 in subjects receiving peritoneal dialysis who had anemia associated with chronic kidney disease in Japan. The registry lists enrollment of 42 and identifies Tanabe Pharma Corporation as the sponsor. The study status is completed. The recorded study start was 2018-01-03, and the primary completion date was 2018-11-22.

Allocation is listed as not applicable, and masking is listed as none. These details align with the single-group design: the record does not describe random assignment to MT-6548 and a control treatment, nor a blinded comparison. The registry’s own note cautions that this is not a randomized comparison and that arms should not be treated as like-for-like controls. There is no second arm against which to estimate a randomized treatment contrast.

The listed intervention is MT-6548, classified as a drug. The primary outcome concerns mean hemoglobin level at Week 20 and Week 24, in g/dL, with a least-squares mean and 95% confidence interval. Its stated timeframe is up to Week 24. The primary analysis population includes subjects with a hemoglobin measurement at least one visit after baseline. The registry does not report the numerical primary result or the number included in that analysis.

Five outcome measures are recorded, while the registry lists no analyses. A detailed protocol, operational description of the intervention, sample-size justification, and statistical analysis plan are not reported in the registry record. The sample-size assumptions associated with planning illustrations should not be mistaken for the original design rationale: the record identifies those illustrations as calculations based on an observed effect, rather than as the trial’s own design. The single-group structure is central to interpretation, because observed hemoglobin levels cannot isolate a treatment effect from time trends, concurrent care, or other influences.

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: This analysis was performed in subjects who measured Hb at least one visit after baseline.

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.

6. Primary Endpoint

The registry lists the primary outcome as Mean Hb Level of Week 20 and Week 24, measured over Up to Week 24.

The primary endpoint is titled “Mean Hb Level of Week 20 and Week 24.” Hemoglobin, abbreviated Hb in the endpoint title, is recorded in g/dL. The registry describes the parameter as a least-squares mean and gives a 95% confidence interval as the measure of dispersion. The stated endpoint timeframe is up to Week 24.

A mean describes the central level of a continuous measurement. A least-squares mean is generally a model-based mean, often adjusted for terms included in the analysis model. That general interpretation does not establish which covariates or model terms were used in this study: those details are not reported in the registry record. Likewise, the title does not make clear whether the reported endpoint combines measurements from the two named weeks or presents values at each; the endpoint result itself is not reported in the registry record.

A hemoglobin endpoint can describe the measured level of anemia-related status over the study timeframe. Its usefulness depends on clear definition of the measurement times, analysis population, and statistical model. The confidence interval would communicate the precision of the estimated mean under the analysis assumptions. However, the estimate and interval bounds are not reported in the registry record, so their magnitude and precision cannot be assessed.

The population description says that subjects had to have at least one hemoglobin measurement after baseline to enter this analysis. This qualification is important: the endpoint does not necessarily represent every enrolled subject. The number analyzed and the treatment of missing measurements are not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a continuous measure, because hemoglobin level is expressed on a numeric scale in g/dL. The registry names a least-squares mean as the summary parameter and a 95% confidence interval as the dispersion measure. These terms describe how a result is intended to be summarized, but they do not reveal the numerical result or the complete analytical procedure. The model specification and the exact method used to calculate the interval are not reported in the registry record.

What does a least-squares mean represent?

In general, a least-squares mean is an estimated mean from a statistical model. Depending on the model, it can account for specified factors or covariates and can differ from a simple arithmetic average of observed measurements. The interpretation depends on which model terms were included, how measurements were structured, and which population was analyzed. The registry does not identify those model details, so it is not possible to determine what adjustments were made or to reproduce the estimate from the record.

The endpoint title names Week 20 and Week 24, and the timeframe extends up to Week 24. This wording indicates the intended measurement period but does not fully describe whether the registry result is one combined estimate or separate estimates for the named weeks. The numerical results are not reported in the registry record. The measurement schedule and the method for handling repeated observations are also not reported.

How should a confidence interval be read?

In general, a confidence interval expresses uncertainty around an estimated quantity under the assumptions of the statistical method. A narrower interval indicates greater precision than a wider interval for the same type of estimate, while the interval’s location conveys the range of values compatible with the data and method. It does not guarantee that the true value lies within a particular interval, and it does not remove limitations in the design or analysis. Here, the 95% confidence interval is specified, but its bounds are not reported in the registry record. Therefore, precision cannot be evaluated.

A confidence interval for a mean is not itself a comparison against an untreated or alternative-treatment group. In a single-group study, it describes uncertainty around the estimated mean for the analysis population under the chosen model. It does not by itself estimate a causal treatment effect. A comparative treatment effect would require a defined contrast, and the registry does not describe a randomized comparator arm.

What does the analysis population mean?

The primary analysis population is described as subjects who measured hemoglobin at least one visit after baseline. This is a post-baseline measurement criterion. It means the analysis was not necessarily defined simply as everyone enrolled; subjects without any qualifying measurement would not meet the stated criterion. The record does not report the resulting analysis count, how baseline measurements were incorporated, or whether additional eligibility rules applied. It also does not explain the handling of subjects with some, but not all, follow-up measurements.

Missing-data methods can influence estimates when measurements are absent, especially if the probability of missingness is related to participants’ outcomes or circumstances. In general, complete-case summaries may represent a selected subset if missingness is informative. Model-based approaches can use incomplete repeated measurements under assumptions, but their validity depends on the model and missingness mechanism. No missing-data method or assumption is reported in the registry record, so it would be inappropriate to assert that a particular method was used.

Why does the design affect statistical interpretation?

In general, random assignment supports a fair comparison by balancing measured and unmeasured characteristics on average across groups. This study is listed as single-group, with allocation not applicable and no masking. It therefore does not offer a randomized between-group contrast. A change over time within one group can be described, but without an appropriate comparison it cannot by itself distinguish a treatment-related effect from natural changes, concurrent care, or other time-varying factors.

The open-label design also means treatment masking was absent. For a laboratory measurement such as hemoglobin, the extent to which this affects measurement depends on study procedures; those details are not reported. The absence of masking should be understood as a design feature, not as proof that measurements were biased.

The registry lists no analyses. It does not report a statistical analysis plan, hypothesis-testing procedure, covariate adjustment, multiplicity strategy, or sample-size justification. In general, multiple outcomes or time points can raise questions about which findings are confirmatory and how uncertainty is controlled. Without a specified plan and numerical results, the status of the Week 20 and Week 24 endpoint as a particular confirmatory test cannot be evaluated from this record.

Planning illustrations associated with the study are described as calculations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The record says these are planning illustrations, not the trial’s own design, and distinguishes participants per arm for non-time-to-event outcomes. Such illustrations are not observed power and do not establish that the single-group study was designed or analyzed according to those assumptions. Their relevance to the actual design is limited because the study had one group, not two equally allocated arms.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures but no analyses. It does not identify a multiplicity adjustment, a hierarchy of endpoints, or a prespecified testing sequence. In general, when several outcomes or time points are examined, the chance of a false-positive finding can depend on how testing is organized. A prespecified strategy can clarify which result is primary and how other results are interpreted. The registry record does not report whether such a strategy was used, so no multiplicity control should be assumed.

The primary endpoint is described as the mean hemoglobin level at Week 20 and Week 24. The record does not clarify whether this represents one combined measure or separate week-specific estimates, and it does not provide numerical results or test statistics. Thus, it is not possible to determine how the named times were analyzed or whether any inferential adjustment was made.

For the primary analysis, subjects needed a hemoglobin measurement at least one visit after baseline. The number meeting this criterion is not reported in the registry record. Nor does the record explain how missing measurements were handled, whether a particular missing-data assumption was adopted, or whether sensitivity analyses assessed alternative assumptions. These omissions limit assessment of potential selection effects and the robustness of the estimated mean.

The record also does not provide a sample-size justification or detailed statistical analysis plan. The described planning illustrations are not a substitute for those materials and do not establish the planned analysis. With no reported primary estimate, confidence interval bounds, or analysis details, the evidence available in the registry record is insufficient to assess multiplicity, missing-data impact, or the prespecified status of individual findings.

11. Safety Results

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

Deaths

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: peritonitis (7.1%), peripheral arterial occlusive disease (4.8%), anaemia (2.4%), cardiac failure chronic (2.4%), myocardial ischaemia (2.4%).

The registry reports safety figures for the MT-6548 group, with 42 at risk for serious adverse events and 12 affected; for other adverse events, it reports 42 at risk and 21 affected. One death is recorded. These are descriptive counts for a single-group study, not estimates of excess risk compared with a control. The record does not establish that the reported events were caused by MT-6548.

The registry lists peritonitis at 7.1% and peripheral arterial occlusive disease at 4.8% among the serious-event terms. Anaemia, chronic cardiac failure, myocardial ischaemia, and gastric polyps are each listed at 2.4%. These are the percentages as recorded; the registry information does not specify the event-term denominators or provide comparative rates. The terms should therefore be read as reported safety listings, not as evidence that treatment caused those conditions.

Counts of affected participants and counts of event occurrences are not interchangeable: one participant can potentially experience more than one event. The registry record does not provide enough detail in these figures to reconstruct event totals, timing, severity beyond the serious classification, or causal assessments. In the absence of a comparison group, the figures describe what was recorded during the study but do not show how safety would compare with another treatment or with no study intervention.

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

The record establishes that a Phase III, open-label, single-group study evaluated MT-6548 in Japanese subjects receiving peritoneal dialysis who had anemia associated with chronic kidney disease. It defines the primary endpoint as mean hemoglobin level at Week 20 and Week 24, expressed in g/dL, with a least-squares mean and 95% confidence interval. It also describes the primary analysis population as subjects with a hemoglobin measurement at least one visit after baseline.

However, the numerical primary result and confidence interval are not reported in the registry record. Therefore, the record does not show the estimated hemoglobin level, its precision, or the direction and size of any change. It also does not allow an assessment of whether a result was statistically distinguishable from a specified value or clinically important. Such conclusions cannot be drawn from the endpoint label or study title.

The single-group design is another key boundary. Even if the primary mean were available, an estimate from this group alone would not provide a randomized comparison with another treatment or a control. The registry notes that arms are not a like-for-like control comparison. Descriptive findings can characterize the study group, but causal attribution requires more than an observed outcome during treatment.

The safety record reports serious adverse events in 12 of 42 at risk, other adverse events in 21 of 42 at risk, and one death. It also lists selected serious-event terms and percentages. These entries describe recorded safety information; they do not establish causation or comparative safety. The missing details on event timing, attribution, and comparison further limit interpretation.

In short, the record conveys the trial’s setting, intervention, endpoint definition, and selected safety counts, but not the primary efficacy estimate. It supports a description of what was studied and what safety counts were recorded, not a conclusion about treatment benefit or comparative risk. The study’s own statistical plan, sample-size rationale, analysis details, and missing-data approach are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically informative first as an example of how design determines the question a result can answer. A single-group study can describe the hemoglobin levels observed among participants during follow-up. It cannot supply the same causal contrast as a randomized comparison, because no concurrent randomized control group is recorded. The registry explicitly warns against treating arms as like-for-like controls.

The endpoint definition also illustrates why the analysis population and measurement schedule matter. The primary measure concerns hemoglobin at Week 20 and Week 24, and only subjects with at least one post-baseline measurement are described as eligible for the primary analysis. Without the analysis population size, model details, and missing-data approach, readers cannot fully evaluate how the reported estimate would relate to all enrolled subjects. In this case, the numerical estimate and interval are not reported either, making assessment of both magnitude and precision impossible.

The safety information offers a separate descriptive perspective. Serious and other adverse-event counts are reported for the treatment group, alongside selected serious-event terms. These data can identify what the registry recorded, but the single-group design and absent comparative rates prevent a controlled comparison of risks. The distinction between recording an event and establishing its cause is essential.

Finally, the record underscores the difference between planning illustrations and a trial’s actual design or observed findings. The planning assumptions are explicitly described as illustrations based on an observed effect, not as the trial’s own design. Such calculations should not be read as observed power or as a replacement for a reported statistical plan. For biostatisticians and clinical researchers, the key lesson is to align every interpretation with the available design, endpoint definition, analysis population, and reporting completeness.

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 largest limitation for interpreting efficacy is that the primary numerical result is not reported in the registry record. Although the endpoint, unit, summary parameter, confidence interval type, timeframe, and analysis-population description are available, the estimate and confidence interval bounds are not. The effect’s magnitude and precision therefore cannot be assessed.

The study is single-group and open-label, with allocation listed as not applicable and masking absent. There is no randomized control group for a like-for-like comparison. This limits causal interpretation of any within-group hemoglobin level or change. The record itself cautions against treating arms as comparable controls.

The primary analysis population includes subjects with at least one hemoglobin measurement after baseline, but the number analyzed is not reported. The registry does not describe how missing measurements were handled, whether all scheduled measurements were required, or whether sensitivity analyses were conducted. The model behind the least-squares mean and confidence interval is also not reported, so adjustment and repeated-measure handling cannot be evaluated.

The endpoint title names Week 20 and Week 24, but the record does not clarify whether the result is a combined estimate or separate week-specific values. The registry lists five outcome measures and no analyses; the multiplicity strategy and statistical analysis plan are not reported. A sample-size justification for the actual design is likewise not reported in the registry record.

Safety interpretation is limited by the absence of a comparison group and by the descriptive nature of the listed counts. The record does not establish event causality or supply enough information to evaluate timing and event-level details. These limitations mean that the registry supports a design and reporting description, but not a complete statistical assessment of efficacy or comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Efficacy and Safety Study to Evaluate MT-6548 in Peritoneal Dialysis Subjects With Anemia Associated With Chronic Kidney Disease in Japan — NCT03402386.
• Registry record last updated 2026-04-06; status last verified 2026-03.
• Results first posted 2021-07-06.
• 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

NCT03402386 is a completed Phase III, open-label, single-group study sponsored by Tanabe Pharma Corporation. It evaluated MT-6548 in subjects in Japan receiving peritoneal dialysis who had anemia associated with chronic kidney disease. Enrollment was 42. The recorded study start was 2018-01-03, and primary completion was 2018-11-22.

The primary endpoint was mean hemoglobin level at Week 20 and Week 24, in g/dL, summarized as a least-squares mean with a 95% confidence interval, up to Week 24. The primary analysis population was described as subjects with at least one post-baseline hemoglobin measurement. The numerical endpoint result and analysis details are not reported in the registry record.

The registry reports serious adverse events in 12 of 42 at risk, other adverse events in 21 of 42 at risk, and one death. These safety figures are descriptive, with no randomized comparator for estimating relative risk. The record lists five outcome measures and no analyses.