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 Vascular Reactivity in Chronic Kidney Disease (CKD) Patients Receiving Paricalcitol Versus Placebo (NCT00915876), a randomized na study. The primary outcome is Change in Circulating ICAM-1 Shown by Absolute Values at Baseline, Day 28 and Day 56.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00915876 |
| Phase | NA |
| Condition | Chronic Kidney Disease |
| Allocation | Randomized |
| Design model | Single Group |
| Masking | Single |
| Enrollment | 41 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Amy Barton Pai |
| Results posted | Yes |
2. Clinical Question
Population
People with chronic kidney disease were the population of interest. The record lists an enrollment of 41, but it does not report detailed eligibility criteria or describe the characteristics of participants who entered the outcome analysis. The study rationale concerns vascular health and circulating substances associated with blood-vessel stress in chronic kidney disease.
Intervention
The intervention was paricalcitol, a drug described in the registry summary as a form of vitamin D. The record states that it is approved to treat high parathyroid hormone levels and frames this study as an investigation of possible effects beyond that use. Dosing, route, adherence, and other treatment details are not reported in the registry record.
Comparator
The comparator was placebo. The study is identified as randomized and single-masked. The registry does not describe the randomization procedure, who was masked, or the precise contents and administration of the placebo. Arm descriptions are not reported in the registry record.
Primary question
The primary outcome concerns change in circulating ICAM-1, measured in nanogram/ml, with absolute values specified at baseline, Day 28 and Day 56. ICAM-1 is described as a measure of vascular reactivity. The clinical question is whether the recorded ICAM-1 measurements over these time points differed between participants assigned to paricalcitol and those assigned to placebo. The registry identifies the outcome but does not report numerical outcome values or a treatment comparison, so the direction and precision of any difference cannot be assessed from the registry record.
3. Trial Design
The registry describes a completed, randomized study comparing paricalcitol with placebo in chronic kidney disease. Enrollment is recorded as 41. The study is listed as single-masked, while the masking details—such as which participants or study personnel were masked—are not reported in the registry record. The phase is recorded as NA. The listed start is 2009-03, and primary completion is recorded as 2011-03.
Although two interventions are named and allocation is identified as randomized, the registered study model is SINGLE GROUP. The registry does not explain this model designation or reconcile it with the two named interventions. The arm descriptions are empty, and information about the allocation procedure, treatment schedule, treatment duration, and participant flow is not reported in the registry record. The outcome timeframe specifies measurement at baseline, Day 28 and Day 56, but does not by itself establish how long participants received treatment.
The total enrollment should not be treated as the number with complete primary-outcome data: the record does not state the analysis sample size for ICAM-1 or how many participants contributed measurements at each time point. Safety denominators are reported separately. The registry also does not describe an analysis population, such as all randomized participants or only participants with available measurements. These gaps matter because the design label alone does not establish how participants were handled in the reported analyses.
The record identifies one primary outcome measure and one analysis, but does not give an analysis method or numerical results. The reason for the study, according to its summary, was to investigate whether paricalcitol might affect blood-vessel response to stress and blood levels of substances associated with vessel blockage. The registry does not report a protocol, sample-size justification, interim analyses, or a fuller statistical plan.
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 | Paricalcitol | Placebo |
|---|---|---|
| STARTED | 20 | 21 |
| Moving Beyond First Dose | 20 | 20 |
| COMPLETED | 20 | 20 |
| NOT COMPLETED | 0 | 1 |
Reasons for not completing this period:
| Reason | Paricalcitol | Placebo |
|---|---|---|
| Adverse Event | 0 | 1 |
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.
Population: One placebo group patient dropped out due to an adverse event is not included in baseline measures or in outcome measures. Assuming 35% variability in circulating ICAM-1 concentrations,46 a sample size of 18 per group is adequate to detect a 50 percentage point difference in the percent in ICAM-1 with 80% power and an = 0.05.
| Characteristic | Unit | Placebo | Paricalcitol | Total |
|---|---|---|---|---|
| Participants analysed | 20 | 20 | 40 | |
| Age, Continuous | years | 67 (SD 11) | 64 (SD 14) | 66 (SD 13) |
| Sex: Female, Male: Female | Participants | 7 | 12 | 19 |
| Sex: Female, Male: Male | Participants | 13 | 8 | 21 |
| Region of Enrollment: United States | participants | 20 | 20 | 40 |
| estimated glomerular filtration rate | mL/min/1.73m2 | 36 (SD 11) | 30 (SD 9) | 35 (SD 10) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Circulating ICAM-1 Shown by Absolute Values at Baseline, Day 28 and Day 56, measured over Day 28 and Day 56.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | nanogram/ml |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is described as change in circulating ICAM-1, with absolute values recorded at baseline, Day 28 and Day 56. The measure is expressed in nanogram/ml, and the registry identifies the parameter as a mean with standard deviation. ICAM-1 is expanded in the record as intracellular adhesion molecule and described as a measure of vascular reactivity.
The study rationale links vascular reactivity with blood-vessel health in chronic kidney disease. In general, a circulating biomarker can serve as a measurable indicator related to a biological process of interest. Its value as an indicator does not, by itself, establish that it fully captures that process or predicts a clinical outcome. The registry record does not provide further detail on the relationship between ICAM-1 and clinical outcomes in this study.
The endpoint title refers to change, while its description specifies absolute values at three time points. Assessing change requires a clearly defined comparison: for example, change from baseline at a specified follow-up or a comparison of trajectories across follow-up. The registry does not report which specific change contrast was used, how repeated measurements were analyzed, or numerical ICAM-1 values. It therefore does not support interpretation of the size, direction, or precision of an observed change.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a randomized comparison of paricalcitol and placebo and names circulating ICAM-1 as the primary outcome. It does not report the endpoint values, an estimated difference between groups, a confidence interval, or a p-value. Consequently, the posted registry information does not establish whether the groups had different ICAM-1 measurements, how large any difference might have been, or how precisely it was estimated. No conclusion about the study’s primary comparison can be drawn from the endpoint description alone.
The outcome is described using absolute values at baseline, Day 28 and Day 56, but the registry does not specify the exact contrast used to define change. A baseline-to-follow-up change, a difference between groups at follow-up, and a comparison of patterns across repeated measurements are distinct statistical questions. Without the analysis definition and results, the phrase “change in circulating ICAM-1” cannot be translated into a particular estimated effect.
In general, a confidence interval describes the range of effect values compatible with the data and the statistical method used. Its width conveys precision: a wider interval indicates less precision than a narrower interval. A p-value, when reported, addresses compatibility with a specified null model; it does not convey the size or clinical importance of an effect on its own. Neither measure is reported for the primary outcome in the registry record, so statistical uncertainty cannot be characterized from this record.
The registry lists a randomized allocation, but it also labels the model SINGLE GROUP while naming paricalcitol and placebo. The record does not explain that apparent design tension. Randomized allocation can support a comparative interpretation when the analysis follows the assigned groups and the outcome data are handled appropriately, but those analysis details are not reported. The record also does not give participant counts contributing to the ICAM-1 analysis or explain missing measurements.
The study summary describes the rationale as examining vascular response to stress and circulating substances associated with blood-vessel blockage. That rationale is not a reported result. In particular, it should not be read as evidence that either intervention changed ICAM-1 or affected clinical events. The registry provides no numerical primary-outcome results with which to assess direction, magnitude, or precision, and it reports no clinical outcome comparison in the material described.
Planning illustrations, where presented, should be distinguished from observed findings. The registry’s stated planning assumptions refer to a normal approximation, equal allocation, a two-sided significance level of 0.05, and effects defined as fractions of an observed effect. Such calculations are design illustrations, not observed power and not evidence of an effect. The registry record does not report a trial-specific sample-size justification, and the primary outcome values needed to independently understand an observed-effect-based illustration are not included in the record.
9. Statistical Methods Explained
The primary outcome is continuous: ICAM-1 is measured in nanogram/ml, and the registry identifies the summary parameter as a mean with standard deviation. The endpoint description specifies measurements at baseline, Day 28 and Day 56. The record does not report the numerical means or standard deviations, an estimated contrast, or the method used to analyze the repeated measurements.
What does a mean and standard deviation describe?
General statistical explanation: A mean describes the central value of a set of measurements. A standard deviation describes how dispersed individual measurements are around that mean. They answer different questions: the mean concerns the group’s average measurement, while the standard deviation concerns variability among measurements. Neither is a measure of uncertainty in the estimated mean by itself. A standard error or confidence interval is generally used to describe uncertainty in an estimate, but such quantities are not reported for this endpoint in the registry record.
Reporting absolute values at multiple time points can help describe how measurements are distributed over follow-up. However, a claim about change needs a defined comparison and an analysis that accounts for the structure of the observations. For example, an analysis might compare change from baseline between randomized groups or model measurements across time. These are general possibilities, not descriptions of the method used in this study. The registry record does not identify the specific contrast, repeated-measures method, or any adjustment for baseline values.
Why does the analysis definition matter?
General statistical explanation: Repeated measurements on the same participant are related rather than independent observations. An analysis of follow-up measurements should account for that dependence where appropriate. Different valid approaches can yield estimates with different interpretations, so the effect definition and model are important for understanding what a result means. The registry’s outcome wording and time points do not identify the analysis model, and numerical results are not reported there.
Randomization is intended to allocate participants to treatment groups by chance. In general, comparisons that preserve randomized assignment can reduce bias from differences in measured and unmeasured characteristics at baseline. The registry records randomized allocation and names paricalcitol and placebo, but it does not report the randomization sequence, concealment procedures, or the analysis population. It also records a SINGLE GROUP model. The record does not clarify how that designation relates to the named interventions, so the analysis structure cannot be fully reconstructed from the registry entry.
The sample-size assumptions describe planning illustrations based on an observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not a statement of the trial’s own sample-size justification. The registry does not report that justification. Any sample-size illustration is a prospective planning calculation under its assumptions; it is not observed power and does not demonstrate that a treatment effect was present. Because the record does not include primary outcome values or an observed effect estimate, the outcome’s magnitude and precision cannot be evaluated from the registry entry.
General statistical explanation: A normal approximation uses a model in which an estimate is treated as approximately normally distributed for purposes such as inference or planning. Whether that approximation is adequate depends on the data and analysis. For continuous outcomes, distributional features and sample size can affect its suitability. The registry does not report diagnostic checks or alternative methods.
How should uncertainty be read?
General statistical explanation: A confidence interval combines an estimated effect with its uncertainty under a specified method. It can show which effect sizes are reasonably compatible with the data and how precisely the study estimates the contrast. A p-value addresses how unusual data would be under a specified null model and assumptions. Neither replaces the effect estimate, and neither alone conveys clinical relevance. The registry record does not report a confidence interval or p-value for the ICAM-1 outcome, so these aspects of the result cannot be assessed.
Over-dispersion is a general issue in statistical models for count data: variability greater than the model allows can make standard errors too small if not addressed. It is not a description of the primary endpoint in this study, which is a continuous measure, and the registry does not report a count-model analysis for ICAM-1. More generally, the choice of statistical model should follow the outcome type and data structure; the specific model used for this study’s primary endpoint is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary outcome measure and one analysis, but the measure includes observations at baseline, Day 28 and Day 56. It does not state whether each follow-up time point was tested separately, whether one time point was designated as the main contrast, or whether a single repeated-measures analysis was used. Because the precise contrast is not reported, the multiplicity implications of possible comparisons cannot be determined from this record.
Multiplicity is a general concern when several hypotheses or contrasts are tested: the chance of at least one apparently notable result can increase as the number of tests grows. Statistical plans may address this by defining a primary contrast in advance or adjusting inference across tests. The registry record does not report whether such a plan or adjustment was used. It also does not report interim analyses or other planned comparisons.
Missing-data handling is not reported in the registry record. The record does not give the number of participants with ICAM-1 measurements at each time point, explain whether any measurements were unavailable, or describe an approach to missing values. Without this information, it is not possible to assess whether the analysis used all randomized participants, only participants with observed measurements, or another population. The analysis population and participant flow for the primary outcome are not reported in the registry record.
These omissions limit interpretation even if numerical estimates are available elsewhere: the analysis population, missing-data assumptions, and handling of multiple time points help define what an estimate represents and how robust its uncertainty assessment may be.
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 |
|---|---|---|---|
| Placebo | 0 | 21 | 0.0% |
| Paricalcitol | 0 | 20 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo | 1 of 21 |
| Paricalcitol | 0 of 20 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | Paricalcitol |
|---|---|---|---|
| Weakness | Nervous system disorders | 1 of 21 | 0 of 20 |
The registry reports serious adverse events for the placebo group as 0 of 21 at risk and for the paricalcitol group as 0 of 20 at risk. It reports other adverse events as 1 of 21 at risk in the placebo group and 0 of 20 at risk in the paricalcitol group. Death counts are recorded as null for both groups. These are the posted counts and denominators; they are not a comparison adjusted for differences in follow-up or participant characteristics.
The registry does not define the “other” adverse-event category in the record described, and it does not provide event descriptions, severity information, timing, or follow-up details. A zero count in the posted category means that no events were recorded in that category for the listed group in this record; it does not establish the absence of every possible adverse event. The death entries are null, which is distinct from a reported numeric count of zero.
These safety figures should be read as descriptive counts. The registry does not report an inferential comparison of adverse events or enough detail to assess how completely events were collected. They should not be treated as evidence of a causal difference between groups.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed randomized study was registered to compare paricalcitol with placebo in chronic kidney disease, with circulating ICAM-1 as its primary outcome. It also specifies the measurement unit and the planned time points: baseline, Day 28 and Day 56. Those details identify the scientific question and the type of measurement under study.
The record does not report numerical ICAM-1 results, an estimated treatment contrast, or uncertainty measures. Therefore, it does not show whether ICAM-1 increased, decreased, or remained similar in either group, nor whether the groups differed. It also does not establish the size or precision of any observed difference. The rationale in the study summary describes what investigators sought to investigate; it is not a report that the proposed effect occurred.
In general, a biomarker result and a clinical outcome are not interchangeable. A measured change in a biomarker, if reported, would describe that measurement under the analysis used; interpreting it as a change in broader health outcomes would require additional evidence. Here, even the numerical biomarker result is not reported in the registry record, and no clinical outcome comparison is given in the described entry.
The adverse-event counts provide limited descriptive information, but event definitions and follow-up details are not reported. The trial’s model designation, analysis population, missing-data methods, and statistical analysis are also not explained. These gaps mean the registry entry cannot support a complete appraisal of the primary comparison. It should be read as a record of the study question and selected design and safety details, not as a complete account of efficacy or safety findings.
13. Why This Trial Matters Statistically
This study illustrates why a clearly named endpoint is only one part of statistical interpretation. The record specifies ICAM-1, its measurement unit, the use of mean and standard deviation, and three time points. Yet without numerical values and a defined contrast, a reader cannot determine what change was estimated or how precisely it was estimated. An outcome label is not a substitute for results.
The record also illustrates the importance of consistency among design fields. Randomized allocation and two named interventions suggest a comparative question, while the model is recorded as SINGLE GROUP. The entry does not explain the relationship between those descriptions. Such ambiguity makes it harder to identify the intended analysis and the population to which its results would apply.
Repeated measurements raise a further statistical issue: results depend on how time points and within-participant measurements are handled. A defined primary contrast, an analysis plan, and clear reporting of missing data help readers distinguish a focused primary test from multiple possible comparisons. Those details are not reported in the registry record.
Finally, planning illustrations should remain separate from findings. The stated assumptions describe a way to calculate sample-size scenarios, but they do not establish observed power or an effect. For this record, the absence of numerical primary-outcome results makes that distinction especially important. Transparent reporting of estimates, uncertainty, analysis populations, and methods is essential for readers to judge what the study can and cannot establish.
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 the primary outcome is that numerical ICAM-1 results are not reported in the registry record. No group means, standard deviations, treatment contrast, confidence interval, or p-value are available in the entry described. The registry names the endpoint as change while specifying absolute values at baseline, Day 28 and Day 56, but it does not define the exact change comparison.
Several design and analysis details are also absent. Although allocation is described as randomized and masking as single, the randomization procedure and identity of the masked parties are not reported. The study model is listed as SINGLE GROUP despite the two named interventions; the record does not explain this. Arm descriptions, dosing and administration details, eligibility criteria, and treatment duration are not reported in the registry record.
The total enrollment is recorded as 41, but the number contributing primary-outcome data at each time point is not given. Participant flow, the analysis population, missing-data methods, and the statistical model are not reported. The registry also does not describe multiplicity handling, interim analyses, or a trial-specific sample-size justification. These omissions prevent a full assessment of precision, analysis choices, and the possibility of bias from unavailable measurements.
Safety reporting is limited to group counts and denominators for serious and other adverse events. Event descriptions and collection details are not reported, and death counts are null. These limitations are specific to the information in the registry record and do not establish whether fuller information exists elsewhere.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Vascular Reactivity in Chronic Kidney Disease (CKD) Patients Receiving Paricalcitol Versus Placebo — NCT00915876.
- Registry record last updated 2016-12-02; status last verified 2016-10.
- Results first posted 2016-12-02.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT00915876 is a completed study titled “Vascular Reactivity in Chronic Kidney Disease (CKD) Patients Receiving Paricalcitol Versus Placebo.” It concerns chronic kidney disease and lists paricalcitol and placebo as drug interventions. Allocation is recorded as randomized, masking as single, and the model as SINGLE GROUP. Enrollment is 41; phase is recorded as NA. The listed start is 2009-03, and primary completion is 2011-03.
The primary outcome is change in circulating ICAM-1, measured in nanogram/ml, with absolute values at baseline, Day 28 and Day 56. The registry identifies a mean and standard deviation but does not report numerical outcome results or the analysis method. Safety counts are reported for serious and other adverse events, while death counts are null. Important details about the primary analysis, missing data, participant flow, and the relationship between the model designation and randomized interventions are not reported in the registry record.