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 The Effect of Paricalcitol on Creatinine Filtration, Secretion and Glomerular Filtration Rate (NCT01163162), a na phase 4 study. The primary outcome is 24-hour Urine Creatinine Excretion Rate.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01163162 |
| Phase | Phase 4 |
| Condition | Chronic Kidney Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 16 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Indiana University |
| Results posted | Yes |
2. Clinical Question
Population
The registry record identifies people with chronic kidney disease as the study population. Enrollment was 16. Further eligibility details, including kidney-disease stage and other inclusion or exclusion criteria, are not reported in the registry record.
Intervention
Participants received 2 mcg of paricalcitol, also identified as Zemplar, for 7 consecutive days after baseline measurements. Kidney-function measurements were repeated after treatment and after a 7-day period off paricalcitol.
Comparator
No separate comparator group is listed. The study is recorded as a single-group study, with allocation listed as NA and masking listed as none. Its measurement sequence includes baseline, treatment, and post-treatment observations within the same participants.
Primary question
The primary endpoint is the 24-hour urine creatinine excretion rate. The study description focuses on whether paricalcitol-related changes in serum creatinine might reflect altered creatinine secretion rather than a change in kidney function. The primary outcome description says that no differences between groups were expected, although a separate group comparison is not described in this single-group record.
3. Trial Design
This is a completed phase 4, single-group study sponsored by Indiana University. The registry lists enrollment of 16 and chronic kidney disease as the condition. Allocation is recorded as NA, and masking as none. These entries describe a study without a listed randomized allocation or a separate control arm; the registry record does not identify a like-for-like comparison group.
The planned measurement sequence was within participants. Kidney function was measured at baseline, after 7 days of paricalcitol treatment, and after 7 days off the treatment. The arm description specifies 2 mcg of paricalcitol for 7 consecutive days before the treatment-period measurement. The brief summary describes use of iothalamate clearance to measure kidney function. The registry record does not give further procedural detail about the measurements or the timing of each assessment beyond the stated intervals.
The record gives a start of 2010-08 and a primary completion of 2011-03, and lists the study status as completed. Those dates describe the registry timeline, not the timing of individual participant visits. The primary outcome timeframe is listed as 1 Week. Secondary outcomes are creatinine clearance and serum creatinine. The record lists 3 outcome measures but reports no analyses. It does not describe the statistical analysis plan, any interim analyses, or the approach to sample-size justification.
The within-participant sequence can describe changes across measurement periods, but it does not provide a concurrent untreated group for comparison. Therefore, changes over time cannot by themselves separate effects related to paricalcitol from other time-related influences. The registry record does not report a protocol for addressing such 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
| Stage | Paricalcitol |
|---|---|
| STARTED | 16 |
| COMPLETED | 16 |
| NOT COMPLETED | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Paricalcitol |
|---|---|---|
| Participants analysed | 16 | |
| Age Continuous | years | 69.6 (SD 9.8) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 16 |
| Region of Enrollment: United States | participants | 16 |
6. Primary Endpoint
The registry lists the primary outcome as 24-hour Urine Creatinine Excretion Rate, measured over 1 Week.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | mg/24hour/day |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the 24-hour urine creatinine excretion rate, with units recorded as mg/24hour/day. It is specified as a mean with a 95% confidence interval, and its timeframe is 1 Week. This measure concerns the amount of creatinine appearing in collected urine over the stated interval. The study description places it in the context of the hypothesis that an observed rise in serum creatinine in paricalcitol trials could be related to reduced creatinine secretion rather than a true reduction in kidney function.
As a general statistical and physiological point, serum creatinine reflects both its production and its removal from the body. A change in serum concentration alone does not identify which process changed. Urinary creatinine excretion and kidney-function measurements can therefore help examine possible explanations for a change in serum creatinine, although the interpretation depends on collection quality, timing, and the full measurement protocol. Those procedural details are not reported in the registry record.
The registry’s endpoint description says that no differences between groups were expected. However, the recorded design is single-group and no separate comparator is listed. The record does not resolve this wording or provide numerical primary-endpoint results. A stated endpoint and rationale explain what investigators intended to assess; they do not establish what the observed data showed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record supports a description of the study question and its measurement sequence, but not a conclusion about the observed effect. It identifies a primary endpoint, 24-hour urine creatinine excretion rate, and specifies a mean and 95% confidence interval. It does not report the endpoint’s observed mean, confidence interval, or any comparison estimate. Numerical results for this primary endpoint are not reported in the registry record.
The study’s stated hypothesis concerns interpretation of a serum creatinine increase: the investigators proposed that reduced creatinine secretion, rather than reduced kidney function, could account for it. The record describes measurements at baseline, following paricalcitol treatment, and after participants had been off treatment. It also identifies iothalamate clearance in the brief summary and lists creatinine clearance and serum creatinine as secondary outcomes. These registry entries describe the planned assessment, not evidence in favor of either explanation.
The single-group structure matters when interpreting any change across the measurement periods. A comparison of a participant with their own baseline can characterize within-participant change, but without a concurrent comparator it cannot control for all changes that might occur over time independently of the intervention. The registry lists no randomized allocation and no separate control arm. It does not report whether any statistical adjustment or other method was used to address this limitation.
The outcome description’s reference to differences “between groups” does not align clearly with the recorded single-group design. The registry record does not explain whether this wording was retained from another protocol description, refers to some other grouping, or reflects an intended comparison that is not represented in the arm listing. It is therefore not possible to identify a specific between-group estimand from the registry entry.
The record lists 3 outcome measures and 0 analyses. That reporting does not establish that no analyses were conducted; it means analyses are not listed in the registry record. No statistical test, effect estimate, p-value, or outcome-specific confidence interval is reported. The precision of any observed change therefore cannot be assessed from the registry entry. Likewise, the recorded enrollment does not establish how many participants contributed data to each measurement or outcome.
In short, the registry conveys a mechanistic question, a short treatment and washout sequence, and selected kidney-related measurements. It does not provide the numerical results needed to judge the size, direction, or precision of the primary endpoint or secondary outcomes. Any interpretation should remain at the level of the question and design rather than implying that the study confirmed or refuted the hypothesis.
9. Statistical Methods Explained
For the primary endpoint, the registry specifies a mean and a 95% confidence interval. A mean is a measure of the central level of a continuous outcome. A confidence interval expresses statistical uncertainty around an estimated quantity under the assumptions of the analysis. In general, a narrower interval indicates greater precision than a wider interval, while the interval’s location indicates which values are compatible with the estimate and its uncertainty. No observed mean or interval for this endpoint is reported in the registry record, so its direction, magnitude, and precision cannot be described.
What does the stated confidence interval mean?
In general, a confidence interval is not a guarantee that the true value lies within a particular calculated interval, nor does it describe the spread of individual participants’ measurements. It quantifies uncertainty in an estimate using a specified statistical procedure. Interpretation depends on the estimand, the analysis population, and the method used to calculate the interval. The registry identifies the intended interval level but does not report the calculation method, the analyzed sample size, or the interval itself. A confidence interval also cannot by itself establish clinical importance; that requires a meaningful context and a clearly defined target of inference.
How does the study’s design shape the analysis?
The design is recorded as single-group, with repeated measurements described at baseline, after treatment, and after the period off treatment. In general, repeated measurements can be analyzed by examining changes within participants, which uses the fact that observations from the same person are related. Such observations should not automatically be treated as independent. The registry record does not identify the statistical model or test used for the repeated measurements, whether the primary analysis compared particular time points, or how within-participant correlation was handled.
The stated outcome is continuous, and the endpoint parameter is the mean. General methods for continuous outcomes may estimate a mean at a particular time, a mean change, or a contrast between measurement periods. These answer different questions. The registry does not identify which contrast, if any, was the primary target, and the primary description’s wording about “between groups” is not reconciled with the single-group design. No specific analysis should be inferred from the endpoint label alone.
Why does dispersion matter?
As a general statistical concept, dispersion describes how much individual measurements vary around a central value. For a continuous outcome, uncertainty in a mean depends not only on the number of observations but also on the variability and the analysis structure. If measurements are repeated within participants, their correlation affects uncertainty as well. None of the observed variability, within-participant correlations, or analysis details are reported in the registry record. It is therefore not possible to reconstruct an interval or estimate from the listed design details.
Over-dispersion is a general concern when a chosen probability model allows less variability than the data actually show. In such a setting, standard errors may be too small and confidence intervals too narrow if the extra variability is not handled appropriately. This concept is not evidence that over-dispersion occurred in this study. The registry does not report a model, residual assessment, or variance diagnostics, and the listed primary endpoint is a continuous measure summarized as a mean.
What can planning calculations tell readers?
Sample-size illustrations based on an observed effect are planning exercises, not evidence that the study had a particular probability of detecting an effect. The assumptions recorded for the planning illustration include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as fractions of an observed effect. Those assumptions do not describe the actual single-group design listed in the registry. The registry record does not report the trial’s own sample-size justification. Planning estimates should not be read as observed power, and a planning illustration cannot replace an outcome estimate or its uncertainty.
In general, observed power is not a useful substitute for presenting an effect estimate and confidence interval. A study’s estimate and precision directly describe what the data say under the analysis, whereas post hoc power largely restates information already reflected in the estimate and its uncertainty. No numerical outcome estimate or interval is registered for this study, so neither an effect-based interpretation nor a precision assessment is possible from the registry entry.
10. Multiplicity, Missing Data and Analysis Populations
The record lists 3 outcome measures: the primary 24-hour urine creatinine excretion rate and the secondary outcomes of creatinine clearance and serum creatinine. Considering multiple outcomes or multiple time-point comparisons can raise a multiplicity issue. As a general concept, repeated opportunities to identify a statistically notable result can increase the chance of a false-positive finding unless the analysis plan defines how results will be interpreted or adjusted. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or which contrasts were intended to be confirmatory.
The record lists 0 analyses. It does not report outcome estimates, p-values, or analysis populations. Thus, it is not possible to determine which outcomes were analyzed, whether all planned outcomes were reported, or whether any multiplicity procedure was applied. The presence of 3 listed outcome measures alone does not establish that each was tested or that a particular adjustment was necessary or used.
Missing-data methods are also not reported in the registry record. Enrollment was 16, but the record does not state the number of participants with completed measurements at each time point, the amount or pattern of missing observations, or how missing measurements were handled. General approaches can differ in the assumptions they make about why data are missing; those assumptions affect interpretation. No approach should be attributed to this study without registry documentation.
The registry record does not define an analysis population, such as whether all enrolled participants or only participants with complete measurements were included in an outcome analysis. It also does not report protocol deviations or exclusions. Consequently, the enrolled number should not be treated as the analyzed number for every outcome.
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 |
|---|---|---|---|
| Paricalcitol | 0 | 16 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Paricalcitol | 3 of 16 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Paricalcitol |
|---|---|---|
| Dizziness | General disorders | 2 of 16 |
| Skin irritation | General disorders | 1 of 16 |
The registry lists 16 participants at risk for serious adverse events in the paricalcitol group and 0 participants affected by serious adverse events. It lists 16 at risk for other adverse events and 3 affected. These are registry counts for the recorded group; they do not, by themselves, establish whether an event was caused by paricalcitol.
The record does not list any serious adverse-event terms. It also does not provide details about the nature, timing, severity, or outcomes of the 3 other adverse events. Deaths are recorded as null, so death information is not reported in the registry record; null should not be interpreted as a reported count of zero.
Adverse-event counts are descriptive safety information. Their interpretation depends on what events were collected, how they were defined, how long participants were followed, and whether events were assessed consistently. The registry entry does not provide those details or a comparison group. Because this was a single-group study with 16 enrolled participants, the listed counts alone cannot establish comparative risk or rule out uncommon harms. The record’s adverse-event figures should be read as reported counts, not as a complete account of safety or a causal assessment.
12. What the Result Does, and Does Not, Mean
The study addresses a specific statistical and physiological distinction: a change in serum creatinine might reflect altered creatinine secretion, or it might reflect a change in kidney function. The registry describes measurements intended to explore that question during paricalcitol treatment and after treatment ended. It names 24-hour urine creatinine excretion as the primary endpoint and identifies iothalamate clearance in the brief summary, alongside secondary outcomes of creatinine clearance and serum creatinine.
That design description does not reveal the study’s findings. Numerical results for the primary and secondary outcomes are not reported in the registry record. There are no registered estimates, confidence intervals, or analysis results with which to assess how much any measure changed, in which direction, or how precisely it was estimated. The stated expectation of no differences between groups is an expectation in the outcome description, not a result.
The single-group structure also limits what can be concluded from changes observed across time. A within-participant sequence can be informative about how measurements differ across periods, but it does not supply a concurrent comparison group. Without registered results and a clear analysis description, even the within-participant pattern cannot be characterized. The record does not establish that a particular mechanism was confirmed or excluded.
These limitations do not make the research question unimportant. They define what the registry can support: an account of the intended measurements, treatment sequence, and listed adverse-event counts. They do not support a claim that paricalcitol did or did not change kidney function, creatinine secretion, or any clinical outcome. Nor do the listed safety counts provide a comparative safety estimate. The meaningful distinction is between a study designed to investigate a question and a registry entry that reports enough results to answer it. This record describes the former but does not report the numerical evidence needed for the latter.
13. Why This Trial Matters Statistically
This study is statistically interesting because its question concerns the interpretation of a biomarker rather than simply a change in one measurement. The brief summary states the hypothesis that an increase in serum creatinine could arise from reduced creatinine secretion rather than an actual reduction in kidney function. Examining more than one related measure can help distinguish possible explanations, provided the measurements and their relationships are reported clearly.
The repeated-measurement sequence is also relevant. Baseline, treatment-period, and post-treatment observations can make within-participant patterns available for analysis. In general, using repeated measurements requires attention to the dependence between observations from the same participant, the chosen time contrasts, and the uncertainty of estimates. The registry does not report the statistical model or numerical results, so it is not possible to assess how those issues were addressed in the analysis.
The registry’s single-group designation illustrates why design and endpoint wording must be read together. The primary outcome description refers to differences between groups, while no separate comparator group is listed. That mismatch leaves the intended comparison unclear. Clear definition of the target comparison is essential for interpreting an estimate: an average at a time point, a within-participant change, and a between-group difference are not interchangeable quantities.
Finally, the entry distinguishes planned measurement from reported evidence. It records outcomes and a hypothesis, but lists no analyses and provides no numerical results for the primary endpoint. This makes the record useful for understanding the study’s question and structure while leaving the statistical evidence unresolved. For clinical researchers, that distinction is central: design features can explain what a study sought to learn, but only reported estimates and their uncertainty show what the collected data support.
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 most important limitation of the registry entry for interpreting this trial is the absence of numerical outcome results. Although a primary endpoint and secondary outcomes are named, their observed values and uncertainty estimates are not reported in the registry record. This prevents assessment of the size, direction, and precision of any change.
The design is listed as single-group, with allocation NA and no masking. No separate comparator is identified, yet the primary endpoint description refers to differences between groups. The registry does not clarify this inconsistency or define the primary contrast. As a result, the estimand—the specific quantity the analysis was intended to estimate—cannot be identified confidently from the entry.
The record also provides limited information about participant eligibility, the measurement procedures, adherence, follow-up completeness, and the analysis population. It does not state how missing measurements were handled, how repeated observations were analyzed, or whether any adjustments were made. These omissions constrain assessment of both potential bias and statistical precision. Enrollment of 16 does not show how many participants contributed data to each outcome.
The listed safety information is similarly limited. The registry gives counts for serious and other adverse events but does not provide event terms, timing, duration of observation, or an assessment of causality. Death information is null rather than a reported count. There is no concurrent group against which to compare the recorded counts.
The registry record does not report the trial’s sample-size justification, an interim-analysis plan, a detailed statistical analysis plan, or a multiplicity strategy. These absences should not be filled with assumptions. They mean the design and analysis cannot be fully audited from the registry entry alone, not that any particular procedure was or was not used.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Effect of Paricalcitol on Creatinine Filtration, Secretion and Glomerular Filtration Rate — NCT01163162.
- Registry record last updated 2013-05-21; status last verified 2013-04.
- Results first posted 2013-05-21.
- 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
NCT01163162 is a completed phase 4, single-group study sponsored by Indiana University. The record lists 16 participants with chronic kidney disease and describes 2 mcg of paricalcitol for 7 consecutive days, with kidney-function measurements at baseline, after treatment, and after 7 days off treatment. The listed primary endpoint is 24-hour urine creatinine excretion rate, summarized as a mean with a 95% confidence interval. Creatinine clearance and serum creatinine are listed as secondary outcomes.
The registry lists no analyses and does not report numerical results for the primary endpoint or secondary outcomes. Its primary outcome description refers to differences between groups, but no separate comparison group is listed. The adverse-event record lists 0 affected by serious adverse events and 3 affected by other adverse events among 16 at risk; event details are not reported. The entry describes the research question and measurement plan, but does not provide enough statistical results to determine the observed outcome pattern or its precision.