Effect of Velphoro on Serum Phosphate and Albumin in Peritoneal Dialysis Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Velphoro on Serum Phosphate and Albumin in Peritoneal Dialysis Patients (NCT04046263), a na phase 4 study. The primary outcome is Serum Phosphate at Baseline.

2. Clinical Question

3. Trial Design

This is a prospective pilot study registered as phase 4, with a single-group, open-label design. Enrollment was 17, and the registry status is completed. The sponsor is University of Colorado, Denver. The registered start date is 2020-02-01 and the primary completion date is 2021-07-31. The registry lists sucroferric oxyhydroxide chewable tablets as the intervention.

The intervention description states that participants received the drug three times daily and that its dose was titrated to keep serum phosphate at goal. The study summary describes a 6-month change in phosphate binder. The specific target phosphate concentration, actual treatment duration for each participant, adherence, and dose adjustments are not reported in the registry record.

Because this is a single-group study, there is no concurrent control group for separating a treatment-associated change from changes that might occur over time for other reasons. Open-label treatment also means participants and study personnel were not masked to intervention assignment. The registry does not report a masking procedure, and allocation is listed as not applicable.

The primary outcome is serum phosphate at baseline. Secondary outcomes listed are serum albumin, serum FGF23, serum PTH, and serum prealbumin. The record indicates 6 outcome measures overall, but gives no numerical outcome results or analysis entries. The details of the additional outcome measures, follow-up measurement schedule, participant flow, and analysis population are not reported in the registry record.

This design can describe measurements among enrolled participants, but the record does not establish a randomized treatment contrast. No protocol-level detail about statistical analysis, sample-size justification, interim analyses, or handling of missing observations is reported in the registry record.

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

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 Serum Phosphate at Baseline, measured over Baseline.

The registered primary endpoint is serum phosphate at baseline, measured in mg/dL and summarized as a mean with standard deviation. It is a continuous laboratory measure: the mean describes the average value in the measured group, while the standard deviation describes how dispersed individual measurements are around that average. The registry identifies the timing as baseline, rather than a change from baseline or a comparison between treatment groups.

As a general clinical-statistical point, serum phosphate is used to characterize phosphate balance, which is relevant to the study's focus on disordered mineral metabolism in peritoneal dialysis. A baseline measurement can describe participants when observation begins and can serve as a reference for later measurements if follow-up data are collected and reported. It does not, by itself, estimate an effect of treatment.

The registry record does not report the baseline mean or standard deviation, a follow-up value, a change estimate, or a confidence interval for serum phosphate. Thus the endpoint's definition and timing are available, but its observed numerical result and any estimate of change are not reported in the registry record. The study summary's stated interest in change over 6 months should not be confused with the registered baseline endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary endpoint as a continuous measure, serum phosphate at baseline, expressed in mg/dL and summarized by a mean and standard deviation. In general, a mean gives a measure of the group's central value. A standard deviation describes the spread of individual observations around that mean; it is not the uncertainty in the estimated mean. The registry record does not report either numerical statistic for this endpoint.

A confidence interval is a general way to express the uncertainty around an estimated quantity, such as a mean or a treatment-related change. It indicates a range of values compatible with the data and the estimation procedure. A narrow interval indicates greater precision than a wide interval, but an interval cannot be interpreted without knowing what quantity it estimates and how it was calculated. No confidence interval for the primary endpoint or other outcomes is reported in the registry record.

For a study with repeated measurements, an analysis might estimate the difference between a participant's baseline and follow-up values, or estimate an average change across participants. These are general statistical approaches, not analyses that can be attributed to this trial. The record specifies baseline serum phosphate as the primary measure, while its brief summary describes interest in improvement over 6 months. It does not report a follow-up time point for the primary endpoint, a change estimate, or the method used to model repeated measurements.

In a single-group study, a within-group change is not equivalent to a randomized comparison. As a general point, the observed change can reflect the intervention as well as other time-related or participant-related influences. A concurrent comparator can help distinguish these explanations when properly designed and analyzed; this trial is recorded as a single group, with allocation not applicable. The registry does not describe an adjusted analysis or another strategy for addressing this limitation.

The sample-size assumptions describe a planning illustration using a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. They state that the effect to detect is a stated fraction of an observed effect. This is a planning setup, not the design used in the registered single-group study and not evidence that the trial had a particular probability of detecting an effect. Any such sample-size figures are planning illustrations, not observed power. The registry does not report the trial's own sample-size justification or the numerical outcome estimate underlying the planning illustration.

The sample-size description distinguishes between participants per arm for ordinary outcomes and total events for time-to-event calculations. This is a general distinction in planning: the unit used depends on the type of outcome and calculation. It does not establish that a time-to-event endpoint was analyzed in this trial. No time-to-event analysis is reported in the registry record.

Multiple outcomes raise a general multiplicity question. If several outcomes are tested, the chance of at least one apparently notable result can increase unless the analysis plan accounts for multiple testing. The registry lists serum albumin, serum FGF23, serum PTH, and serum prealbumin as secondary outcomes, alongside the primary measure, and reports 6 outcome measures overall. It does not report a multiplicity adjustment, hierarchy among secondary outcomes, or a statistical analysis plan. The remaining outcome descriptions are not reported in the registry record.

For safety, counts of participants affected describe how many people were recorded with events, while counts of events can describe repeated events in the same person. The adverse-event information gives participant counts at risk and affected, but does not specify whether any participant experienced more than one event or whether the serious and other adverse-event categories overlap. The reported counts should therefore be read as separate registry entries rather than added together.

General statistical interpretation also depends on defining the analysis population and handling missing data. For example, analyses may include all enrolled participants, those who started the intervention, or those with measurements at specified visits; these choices can lead to different results. The registry record does not report an analysis population, missing-data method, or reasons for missing measurements. It also reports 0 analyses, so no inferential result or model specification is available to evaluate.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Intervention")
n   <- c(17)
m   <- c(7.47)
sp  <- c(1.76)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Intervention  17  7.470  1.760  6.565  8.375

11. Multiplicity, Missing Data and Analysis Populations

The registry lists serum albumin, serum FGF23, serum PTH, and serum prealbumin as secondary outcomes, and records 6 outcome measures overall. The primary measure is baseline serum phosphate. The record does not report a multiplicity strategy, such as a prespecified ordering of outcomes or an adjustment for testing multiple outcomes. It also does not report numerical results or analysis entries for the listed measures. The descriptions of the other outcome measures are not reported in the registry record.

Missing-data handling is important because outcome estimates may depend on which participants have measurements at each visit and how unavailable values are treated. This is a general statistical consideration. The registry record does not report the number of participants with outcome measurements, reasons for missing values, an imputation method, or another missing-data approach.

The analysis population is also not reported in the registry record. It is therefore unclear from the registry information which participants would contribute to each outcome analysis or whether the analyzed group differed from the enrolled group. The record reports 17 enrolled participants but does not report a participant-flow account or outcome-specific analysis denominators.

These omissions limit assessment of both the completeness and the interpretability of outcome reporting. They do not establish that data were missing, that a particular analysis population was used, or that multiplicity adjustments were omitted from all study materials; they mean those details are not reported in the registry record.

12. 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: death (11.8%).

The registry reports 2 participants with serious adverse events among 17 at risk and 9 participants with other adverse events among 17 at risk. It separately reports 2 deaths. Death is also the listed top serious adverse event term, at 11.8%. These are descriptive entries for the intervention group, not comparisons with a control group.

The counts do not show when events occurred, whether they were considered related to treatment, or what caused the deaths. The record does not clarify whether the participants counted under serious events, other events, and deaths overlap. The categories should not be added together to infer a total number of distinct affected participants. Nor do the entries establish whether every event was captured over the same observation period.

As a general point, safety counts from a small, uncontrolled group describe what was recorded in that group; they do not by themselves estimate how event rates compare with another treatment or with no treatment. The registry record does not report comparative safety estimates, event-level detail, or a formal assessment of causality.

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

The record identifies a prospective pilot of sucroferric oxyhydroxide in peritoneal dialysis patients and specifies baseline serum phosphate as its primary measure. It also lists albumin, FGF23, PTH, and prealbumin as secondary outcomes. These details describe what the study set out to measure, not what the measurements showed.

The brief study summary frames the purpose as assessing whether a 6-month change in phosphate binder improves disordered mineral metabolism and nutrition status. But the registry record does not report numerical outcome results, a change from baseline, or uncertainty around an estimated effect. It therefore does not establish the size, direction, or precision of any change in phosphate or the listed secondary measures.

The single-group, open-label design has no randomized control comparison. As a general statistical point, an observed change over time in a single group cannot, by itself, distinguish an intervention-associated effect from other influences that may change over time. The registry record does not report an adjusted analysis or design feature that would support a controlled causal comparison.

The reported safety entries describe participants affected by serious and other adverse events and deaths, but lack event timing, causality, and details about overlap among categories. They should not be read as comparative risks or as proof about whether the intervention caused any event.

Accordingly, the registry supports a description of the study design, intended measures, enrollment, and recorded safety counts. It does not support a claim that treatment did or did not improve phosphate, albumin, nutrition status, or other outcomes. Such conclusions would require reported outcome estimates, their uncertainty, and enough information about analysis populations and missing data to assess how the estimates were obtained.

14. Why This Trial Matters Statistically

This trial is statistically notable as a pilot with a focused clinical question but a single-group design. Such studies can characterize how an intervention is administered and what measurements are collected, and may motivate further study. Their observations do not provide the same treatment contrast as a randomized comparison. This is a general distinction in study design rather than a conclusion about the outcome of this particular trial.

The registry makes an important distinction between an intended treatment-period question and the registered primary endpoint, which is serum phosphate at baseline. Baseline description can characterize the starting group, but treatment-related change requires follow-up data and an analysis that estimates that change. The registry record does not report those numerical outcomes.

The listed secondary measures span mineral metabolism and nutrition-related measurements, while the record indicates 6 outcome measures overall. When multiple outcomes are considered, prespecified priorities and clear reporting help readers understand which findings were central and how uncertainty was handled. The multiplicity approach and details for all outcome measures are not reported in the registry record.

Finally, the record's safety counts illustrate why event descriptions need context: participant counts, event categories, timing, causal attribution, and a comparator each affect interpretation. The registry provides some participant counts but not the contextual detail or comparative estimates. Statistical interpretation is therefore constrained not only by the small pilot enrollment but also by the absence of reported outcome analyses and safety detail.

15. 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 trial enrolled 17 participants and used a single-group, open-label design. It had no like-for-like control group, so the design does not offer a randomized estimate of treatment effect. This limitation is especially relevant because the study summary describes assessing change over 6 months, while the registry's primary endpoint is serum phosphate at baseline.

Most importantly, numerical results for the primary and secondary outcomes are not reported in the registry record, and the record lists 0 analyses. There is consequently no reported estimate of mean serum phosphate, change from baseline, uncertainty interval, or statistical test to interpret. The registry identifies 6 outcome measures overall, but the description of all measures and any analysis hierarchy are not reported in the registry record.

The record does not report the eligible population criteria in detail, participant characteristics, outcome-specific denominators, measurement schedule beyond the baseline primary endpoint, adherence, dose changes, or handling of missing data. These details matter for determining who contributed to each analysis and how representative the measurements may be.

For safety, the record includes counts of participants affected and deaths but does not report timing, causes, relatedness, or overlap among categories. It therefore provides limited context for interpreting the adverse-event entries. Sample-size justification, interim analyses, and the statistical analysis plan are not reported in the registry record. These limitations restrict interpretation of the study's intended clinical question and do not establish what the study's unreported findings were.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effect of Velphoro on Serum Phosphate and Albumin in Peritoneal Dialysis Patients — NCT04046263.
• Registry record last updated 2022-08-31; status last verified 2022-08.
• Results first posted 2022-08-31.
• 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.

19. Record Summary

NCT04046263 is a completed phase 4, prospective pilot sponsored by University of Colorado, Denver. The registry lists a start date of 2020-02-01, a primary completion date of 2021-07-31, and enrollment of 17. The study is recorded as single-group and open-label, with allocation not applicable.

Participants received sucroferric oxyhydroxide chewable tablets three times daily, with dose titration to keep serum phosphate at goal. The summary describes a 6-month treatment period. The primary measure is serum phosphate at baseline, in mg/dL, summarized as a mean and standard deviation. Secondary outcomes include serum albumin, FGF23, PTH, and prealbumin.

Numerical outcome results and analyses are not reported in the registry record. Safety entries report 2 participants with serious adverse events, 9 with other adverse events, and 2 deaths; the serious event term Death is listed at 11.8%.