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 Tekturna on Endothelial Function and Endothelial Progenitor Cells in Patients With Early Atherosclerosis (NCT01067326), a randomized phase 3 study. The primary outcome is Endothelial Progenitor Cells (EPC).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01067326 |
| Phase | Phase 3 |
| Condition | Endothelial Dysfunction |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 22 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Mayo Clinic |
| Results posted | Yes |
2. Clinical Question
Population
Patients with early atherosclerosis; the listed condition is endothelial dysfunction. The registry record does not report further eligibility details in the trial information.
Intervention
Aliskiren, identified in the brief summary by the brand name Tekturna. The regimen is 150 mg once daily for 4 months.
Comparator
Placebo, described as 1 pill per day by mouth for 4 months.
Primary question
How do endothelial progenitor cell counts, measured in peripheral blood at baseline and 4 Months, compare in the aliskiren and placebo groups? Numerical results for this endpoint are not reported in the registry record.
The trial’s brief summary states a broader hypothesis: long-term Tekturna treatment would improve endothelial function and the production and function of endothelial progenitor cells, compared with placebo, alongside changes in inflammation and oxidative stress. It also describes an expected increase in Reactive Hyperemia Peripheral Arterial Tonometry indexes. Those statements describe the study rationale and hypothesis, not observed effects.
The listed primary endpoint is endothelial progenitor cell counts. Blood cells were assessed for the markers CD34, CD133, and KDR using flow cytometry. Systolic and diastolic blood pressure are listed as secondary outcomes. The registry record does not report numerical comparative results for these measures or explain how the broader proposed outcomes were related to the primary endpoint.
3. Trial Design
This was a randomized, parallel-group, phase 3 trial with quadruple masking. The listed interventions were aliskiren and placebo. The registry record reports enrollment of 22 and identifies Mayo Clinic as the sponsor. It records the start as 2010-02 and primary completion as 2011-12. The status is terminated.
Random allocation is intended to create groups whose measured and unmeasured characteristics are comparable on average, although it cannot guarantee balance in a small trial. A parallel-group design assigns participants to one study group for the intervention period rather than having each participant receive both treatments in sequence. The registry record does not describe the allocation sequence or how it was concealed.
Quadruple masking indicates that the record classifies the trial as masked at four levels, but the identities of those levels and the practical masking procedures are not reported in the registry record. The two listed regimens were aliskiren at 150 mg once daily for 4 months and placebo at 1 pill per day by mouth for 4 months.
The registry record does not report why the trial was terminated, whether the planned enrollment was reached, or whether termination affected follow-up or outcome collection. It also does not report a protocol, a sample-size justification from the trial’s original design, the planned statistical analysis, or details of participant flow. Those omissions limit assessment of how closely the completed trial followed its original plans.
The endpoint timeframe is baseline and 4 Months. The record does not explain whether measurements were collected at other times, how missing measurements were handled, or which analysis population was used. Without those details and numerical outcome results, the design features alone cannot establish the size or precision of any treatment-group difference.
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 | Aliskiren | Placebo |
|---|---|---|
| STARTED | 14 | 8 |
| COMPLETED | 12 | 5 |
| NOT COMPLETED | 2 | 3 |
Reasons for not completing this period:
| Reason | Aliskiren | Placebo |
|---|---|---|
| Adverse Event | 0 | 2 |
| Withdrawal by Subject | 1 | 0 |
| Early Study Termination | 1 | 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.
| Characteristic | Unit | Aliskiren | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 12 | 5 | 17 | |
| Age Continuous | years | 43.1 (SD 17.5) | 51.0 (SD 20.7) | 45.4 (SD 18.2) |
| Sex: Female, Male: Female | Participants | 7 | 1 | 8 |
| Sex: Female, Male: Male | Participants | 5 | 4 | 9 |
| Region of Enrollment: United States | participants | 12 | 5 | 17 |
6. Primary Endpoint
The registry lists the primary outcome as Endothelial Progenitor Cells (EPC), measured over Baseline, 4 Months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | counts per 100,000 gated events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is endothelial progenitor cells, abbreviated EPC. The registry describes peripheral blood mononuclear cells stained for the cell-surface antigens CD34, CD133, and KDR, then counted by flow cytometry. The measurement unit is counts per 100,000 gated events. Results are specified as medians with inter-quartile ranges, with measurements at baseline and 4 Months.
In general, EPC measurements are used to characterize cells identified by selected markers that are associated with the endothelial progenitor cell definition used in the assay. Flow cytometry classifies and counts cells according to their measured characteristics, including the markers applied in this trial. Reporting counts per 100,000 gated events expresses the count relative to a specified set of events selected for analysis; the registry record does not provide further gating details.
A median describes the central position of a distribution, while the inter-quartile range describes its spread across the middle portion of observations. These summaries can be useful when measurements are skewed or include values that would strongly influence a mean. They do not, by themselves, show the treatment-group contrast, its uncertainty, or whether changes from baseline differed between groups.
The endpoint is relevant to the trial’s stated interest in EPC production and function, but the listed measure is a cell count. The registry record does not report a numerical result for the endpoint or a functional EPC assay result. The measurement description therefore identifies what was counted, not whether the groups differed or what such a difference would mean clinically.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary EPC endpoint and states that measurements were planned at baseline and 4 Months. It does not report numerical values for the EPC measurements by treatment group, a between-group estimate, a confidence interval, or a p-value. The endpoint is not reduced in the registry record to one comparison because it has several categories or time points. Consequently, the posted information does not support a numerical estimate of the treatment effect on EPC counts.
The brief summary expresses a hypothesis about endothelial function, EPC production and function, inflammation, oxidative stress, and Reactive Hyperemia Peripheral Arterial Tonometry indexes. A hypothesis is not a result. The registry record does not report numerical results for those proposed outcomes. Systolic and diastolic blood pressure are listed as secondary outcomes, but their comparative results are also not reported in the registry record.
Without a group contrast and a measure of its uncertainty, neither the magnitude nor the precision of an effect can be assessed. In general, a confidence interval describes a range of values compatible with the data and the method used to calculate it; a narrow interval indicates greater precision than a wide interval. No such interval is reported for the primary endpoint. Likewise, a p-value alone would not show the size or clinical importance of an effect, and no primary-endpoint p-value is reported.
Enrollment is reported as 22, while the adverse-event information gives group-specific numbers at risk of 12 for aliskiren and 5 for placebo. These figures describe different record elements and should not be combined or used to infer participant flow. The record does not state why the numbers differ, whether they refer to the same analysis population, or how many participants had evaluable primary-outcome measurements.
The trial’s terminated status is important context, but it does not identify the reason for termination or establish that the study stopped because of benefit, harm, or lack of effect. Those explanations are not reported in the registry record. In the absence of outcome results and termination details, the status should not be interpreted as evidence for any particular treatment conclusion.
Any planning illustrations based on an observed effect are not observed power and are not a substitute for trial results. The stated planning assumptions include a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect defined as a fraction of the observed effect. Such calculations describe hypothetical planning under assumptions; they do not demonstrate what the trial found, and the registry record does not provide enough outcome information to assess the observed effect itself.
9. Statistical Methods Explained
What does a median with an inter-quartile range describe?
The registered primary endpoint is summarized using a median and inter-quartile range. In general, the median is the midpoint of an ordered set of measurements: half of the observations lie at or below it and half at or above it, subject to ties and the conventions used. The inter-quartile range spans the middle half of the measurements. Together, these summaries describe a distribution’s center and spread without assuming that the measurements follow a symmetric, bell-shaped distribution.
This choice can be useful for biological measurements whose values may be unevenly distributed. A few unusually high or low observations have less influence on the median than they would on an arithmetic mean. However, a group median and inter-quartile range do not directly quantify a difference between groups, and overlap between inter-quartile ranges is not a formal test of that difference. The registry record does not provide the group summaries or a treatment contrast for EPC counts.
What is measured by flow cytometry?
The registry describes peripheral blood mononuclear cells stained for CD34, CD133, and KDR, followed by flow-cytometric counting. In general, flow cytometry measures features of individual cells as they pass through an instrument. Staining identifies selected markers, and analytical gates define which events are included in a particular count. The reported unit, counts per 100,000 gated events, relates the count to the events retained by the gating process.
Gating and marker definitions matter because they determine which events contribute to the measured endpoint. The registry record gives the named markers and unit, but does not report detailed gating rules, laboratory quality-control procedures, reproducibility, or whether laboratory personnel were masked to treatment assignment. Those details are relevant to understanding how consistently the cell count was obtained.
What does randomization contribute?
Randomization assigns treatment using a chance-based process. In general, its purpose is to reduce systematic differences in prognosis between groups, so that a properly analyzed treatment contrast can be interpreted as an estimate of the effect of assignment to the interventions. Randomization does not ensure identical groups, particularly in a small trial, and it cannot correct for missing outcomes or deviations from the planned analysis.
The registry identifies the trial as randomized and parallel-group. It does not report the sequence-generation method, allocation concealment, stratification factors, or any adjustments planned to account for baseline characteristics. It is therefore possible to describe the broad design, but not to evaluate the detailed implementation of randomization from the registry information.
What does masking mean for interpretation?
The registry classifies the trial as quadruple-masked. In general, masking can reduce the chance that knowledge of treatment assignment influences participant behavior, clinical management, outcome assessment, or analytic choices. The potential value of masking depends on who was masked and whether the treatments could be distinguished in practice. The registry record does not identify the four masked roles or describe procedures for maintaining or assessing masking.
How should uncertainty and significance be understood?
In general, an effect estimate describes the magnitude and direction of a contrast, while a confidence interval communicates its statistical uncertainty under a specified method. A p-value addresses how compatible the data are with a particular null hypothesis under model assumptions; it does not measure the probability that the null hypothesis is true or the clinical importance of a result. Interpretation should consider the estimate and its uncertainty together, not rely on a significance threshold alone.
The registry record does not report an EPC treatment contrast, confidence interval, or p-value. It also does not report a statistical analysis plan, including the test or model used for the primary endpoint. No claim about statistical significance or precision can therefore be drawn from the endpoint description alone.
Why can over-dispersion matter?
In general, count outcomes may vary more than a simple statistical model expects. This is called over-dispersion. If a model assumes less variability than the data actually contain, standard errors can be too small and confidence intervals too narrow. Suitable methods can account for extra variability, but choosing a method requires information about the data and the planned analysis. The registry record does not report a model for the EPC counts or whether over-dispersion was assessed.
The endpoint is described using medians and inter-quartile ranges, but that description does not establish how a group comparison was tested. The registry record does not say whether analysis focused on measurements at 4 Months, changes from baseline, or another contrast. Those distinctions affect the interpretation of any treatment estimate.
What do the planning assumptions mean?
The record states that planning illustrations use a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It also describes the target effect as a stated fraction of the observed effect. In general, a planning calculation asks how much information a future study might need to detect an effect under assumptions about variability, allocation, and the statistical test. It is not an observed trial result.
Participants per arm for a stated power level are planning illustrations, not observed power. Observed power is not a useful replacement for an effect estimate and its confidence interval. Planning calculations based on an observed effect can also depend strongly on how stable that estimate is. The record’s stated assumptions do not constitute the original trial’s sample-size justification, which is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 4 outcome measures and 4 analyses. The primary endpoint has several categories or time points and is not reduced to one comparison in the record. Systolic and diastolic blood pressure are listed as secondary outcomes. The brief summary also discusses endothelial function, EPC function, inflammation, oxidative stress, and Reactive Hyperemia Peripheral Arterial Tonometry indexes as part of the study hypothesis.
When a study examines multiple outcomes, time points, or comparisons, the chance of at least one apparently unusual result can increase if each is evaluated separately. In general, a multiplicity strategy may define a primary comparison, adjust significance thresholds, or use a prespecified sequence of tests. The registry record does not report whether such a strategy was planned or used, how the listed analyses were grouped, or which analyses were considered confirmatory.
The record does not report missing-data counts or methods for handling missing outcomes. It also does not identify the analysis population, such as whether the primary analysis included all randomized participants or only participants with an available measurement. The numbers at risk listed for adverse events do not establish the population used for the EPC analysis.
These omissions prevent assessment of whether the analysis respected a prespecified outcome hierarchy, how missing measurements could have influenced estimates, or whether results were robust to alternative analysis populations. No assumptions about the missingness mechanism or analysis choices can be made from the registry record.
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 |
|---|---|---|---|
| Aliskiren | 0 | 12 | 0.0% |
| Placebo | 0 | 5 | 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 |
|---|---|
| Aliskiren | 0 of 12 |
| Placebo | 2 of 5 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Aliskiren | Placebo |
|---|---|---|---|
| Rash | Skin and subcutaneous tissue disorders | 0 of 12 | 1 of 5 |
| Irritated bowel | Gastrointestinal disorders | 0 of 12 | 1 of 5 |
The registry’s adverse-event information lists aliskiren with 12 participants at risk and placebo with 5 participants at risk. Serious adverse events affected 0 participants in each group. Other adverse events affected 0 participants in the aliskiren group and 2 participants in the placebo group. These are the recorded counts; they do not, on their own, establish a comparative safety effect.
The number at risk is the denominator associated with the adverse-event record for that group. It is not necessarily the same as the enrollment figure or the population analyzed for the primary endpoint. The registry record does not explain the group-specific numbers at risk, provide event descriptions for the other adverse events, or report how long participants were observed for safety. Deaths are not reported in the registry record.
Zero recorded serious adverse events in these groups does not establish that serious events could not occur, and the other-event counts do not establish that one intervention caused or prevented those events. Safety interpretation depends on the event definitions, follow-up, completeness of reporting, and the number of participants observed. These details are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, quadruple-masked, parallel-group trial compared aliskiren with placebo in patients with early atherosclerosis. It identifies EPC counts as the primary endpoint, measured at baseline and 4 Months, and describes the cell markers and assay approach. It also records blood pressure as a secondary outcome and includes an adverse-event summary.
It does not establish whether aliskiren changed EPC counts, endothelial function, blood pressure, inflammation, oxidative stress, or any other proposed measure. Numerical primary and secondary outcome comparisons are not reported in the registry record. Without effect estimates and uncertainty, the direction, size, and precision of any between-group difference cannot be assessed.
The trial’s terminated status does not by itself explain what happened to the planned study or its participants. The reason for termination, completeness of follow-up, and relationship between enrollment and the adverse-event populations are not reported in the registry record. These gaps make it especially important not to treat the record’s hypothesis or design as evidence of an outcome.
In general, a trial’s statistical results should be interpreted alongside its design, analysis population, missing-data handling, and prespecified analysis plan. Those details are not reported in the registry record. The available information is therefore useful for understanding the clinical question and measurement approach, but it does not support a conclusion about efficacy or a definitive comparison of safety.
Planning illustrations are hypothetical calculations, not observed power or trial findings. Their assumptions may help frame future study design, but they cannot substitute for reporting the actual treatment contrast and its uncertainty.
13. Why This Trial Matters Statistically
This trial is statistically notable because its stated biological hypothesis is broader than its registered primary measurement. The brief summary discusses endothelial function, EPC production and function, inflammation, oxidative stress, and Reactive Hyperemia Peripheral Arterial Tonometry indexes, while the primary endpoint is a marker-based EPC count. Distinguishing a rationale from a defined endpoint is essential: a proposed mechanism does not become a measured result unless the relevant outcomes and analyses are reported.
The endpoint uses a median and inter-quartile range, which describe the distribution without assuming that the data are symmetric. That summary choice is relevant for cell-count measurements, but it does not reveal the comparative effect or how uncertainty was estimated. The registry record does not provide those results or the statistical method used for a group comparison.
The trial also illustrates why design and outcome reporting must be considered together. Randomization and masking are recorded, but details about implementation, analysis populations, missing data, and multiplicity are not reported in the registry record. Its terminated status and the differing group-specific adverse-event populations add context that cannot be resolved from the record alone.
For researchers, the central statistical lesson is to separate trial intent, measurement, and evidence. The hypothesis identifies what investigators expected; the endpoint description identifies what was to be measured; comparative estimates and their uncertainty would show what the observed data support. Without the latter, neither a positive nor a negative treatment effect can be inferred.
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 registry record identifies a primary endpoint but does not report its numerical results, treatment contrast, confidence interval, or p-value. It therefore does not permit assessment of effect magnitude, direction, or precision. The endpoint is described at baseline and 4 Months, but the record does not specify the intended comparative estimand or statistical test.
The trial is marked terminated, but the reason for termination is not reported in the registry record. Participant flow, completion of follow-up, and the relationship between enrollment of 22 and the group-specific adverse-event populations are also not described. The adverse-event entries list 12 at risk for aliskiren and 5 for placebo, but the record does not explain these denominators.
Details that would support evaluation of the endpoint include the gating procedure, laboratory quality control, missing-measurement handling, and the analysis population. These are not reported in the registry record. The record also does not provide the allocation procedure, concealment details, identities of the masked groups, or a statistical analysis plan.
The brief summary describes several biological and functional outcomes, while the primary endpoint is a cell count. The registry record does not report numerical results for the broader proposed measures or clarify how the 4 listed outcome measures and 4 analyses were prioritized. It also does not report a multiplicity strategy.
These are limitations of what can be interpreted from the registry information; they do not establish that the underlying study lacked these procedures or data. They mean that the available record cannot resolve those methodological questions or support a quantitative conclusion about the interventions.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Effect of Tekturna on Endothelial Function and Endothelial Progenitor Cells in Patients With Early Atherosclerosis — NCT01067326.
- Registry record last updated 2013-02-13; status last verified 2013-01.
- Results first posted 2013-02-13.
- 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
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18. Record Summary
NCT01067326 is a phase 3, randomized, quadruple-masked, parallel-group trial sponsored by Mayo Clinic. It enrolled 22 and is listed as terminated. The record gives a start of 2010-02 and primary completion of 2011-12.
The interventions were aliskiren, 150 mg once daily for 4 months, and placebo, 1 pill per day by mouth for 4 months. The primary endpoint was EPC counts per 100,000 gated events, measured at baseline and 4 Months using flow cytometry for CD34, CD133, and KDR. Systolic and diastolic blood pressure were listed as secondary outcomes.
Numerical primary- and secondary-outcome comparisons, the reason for termination, and key analysis details are not reported in the registry record. Serious adverse events were recorded for 0 participants in each adverse-event group; other events were recorded for 0 in the aliskiren group and 2 in the placebo group. Deaths are not reported in the registry record.