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 Characterization of Brachial Arterial t-PA Release, Endothelial Function, Obesity and Inflammation (NCT00780481), a na na study. The primary outcome is Peak t-PA Release.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00780481 |
| Phase | NA |
| Condition | Obesity |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Vanderbilt University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns subjects in an obesity-related research context. The registry record does not report detailed eligibility criteria or a fuller description of the study population.
Intervention
The intervention is intrabrachial bradykinin, administered at 0, 10, 20, and 40 ng/100cc/min. The described assessments include flow mediated vasodilation, radial artery tonometry, strain gauge plethysmography and blood sampling.
Comparator
The record describes a single-group study, not a randomized comparison. The dose sequence includes a 0 dose, but the record does not establish a separate control group or a like-for-like between-group comparison.
Primary question
The primary endpoint is Peak t-PA Release. The study description frames the work as a mechanistic investigation relating t-PA release to vascular function and other measures, rather than as a treatment comparison.
The registry summary states that t-PA release is impaired in obese subjects and describes the goal of comparing t-PA release with Flow Mediated Vasodilation, Radial Artery Tonometry, and other markers of endothelial function and oxidative stress. This is the rationale recorded for the investigation, not a result established by the posted endpoint data.
The secondary outcomes include Peak FMD, Radial Artery Elasticity, and lipid levels, PAI-1 levels, CRP levels, F2 Isoprostanes and other biomarkers of inflammation and obesity. The record therefore describes a broad set of physiological and biomarker measurements around the main t-PA release question. It does not report detailed eligibility criteria, a separate comparator group, or a numerical result for the primary endpoint.
3. Trial Design
The registry record describes a single-group study with no masking. Allocation is listed as NA, and the record explicitly indicates that the study is not a randomized comparison. Its design should therefore be understood as a physiological or mechanistic investigation, not as a controlled estimate of treatment effect between assigned groups.
The intervention is bradykinin. According to the arm description, participants undergo flow mediated vasodilation and radial artery tonometry before receiving intrabrachial bradykinin at 0, 10, 20, and 40 ng/100cc/min. Strain gauge plethysmography and blood sampling at each dose are described as methods for evaluating t-PA release. The arm description also mentions blood draws for other measures, but the remaining text is incomplete in the registry record; additional details are not reported in the registry record.
The primary endpoint is Peak t-PA Release, with a timeframe of Single Study day. Secondary outcomes include Peak FMD, Radial Artery Elasticity, and measures concerning lipids, PAI-1, CRP, F2 Isoprostanes, inflammation and obesity. The registry record lists enrollment as 13. This is a registry enrollment figure; it does not establish how many participants contributed usable endpoint data.
The study began in 2007-01, has a primary completion date of 2011-01, and is marked TERMINATED. The reason for termination and the timing or circumstances of that decision are not reported in the registry record. The record does not report the planned statistical analysis, sample-size justification, interim analyses, or a fuller account of study conduct. No randomized control arm or masked assessment is described.
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.
Before assignment: The data for this study was lost. The total number of participants enrolled/completed was pulled from IRB records. Participant age was between 18-65 per protocol. All participants were enrolled in the United States. No other data is available
Overall Study
| Stage | Bradykinin |
|---|---|
| STARTED | 13 |
| COMPLETED | 13 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Data was lost
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: Data was lost, we do not have sex/gender
| Characteristic | Unit | Bradykinin |
|---|---|---|
| Participants analysed | 13 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 13 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | — |
| Sex: Female, Male: Male | Participants | — |
| Region of Enrollment: United States | participants | 13 |
6. Primary Endpoint
The registry lists the primary outcome as Peak t-PA Release, measured over Single Study day.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is Peak t-PA Release, described in the registry as tPA Release and assessed over a Single Study day. Tissue-type plasminogen activator (t-PA) is the biological measure at the center of the study's stated mechanistic question. The study description relates its release to vascular function and other markers, including flow mediated vasodilation and radial artery tonometry.
The intervention description says that strain gauge plethysmography and blood sampling at each bradykinin dose are used to evaluate t-PA release. In general, a peak endpoint is intended to capture the maximum recorded response under the specified assessment conditions. That makes it relevant to a question about how vascular responses and t-PA release relate during the described protocol. The registry record does not give a unit, a numerical value, a dispersion measure, or a detailed operational definition for the primary endpoint. The primary endpoint population field states “Data was lost.”
Because the endpoint data were lost, there is no posted primary estimate to interpret for magnitude or precision. The endpoint's presence in the registry identifies what the study intended to assess; it does not supply evidence about the observed level of t-PA release or its relationship with the other measures.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the registry record does not contain usable primary endpoint data: its population field for Peak t-PA Release states “Data was lost.” No numerical result, unit, or measure of variability is reported for that endpoint. Consequently, the posted record cannot establish the observed peak t-PA release, how variable it was, or how precisely it was estimated.
The registry describes an intended mechanistic assessment. Participants were to undergo vascular function measurements and receive intrabrachial bradykinin at 0, 10, 20, and 40 ng/100cc/min, with plethysmography and blood sampling used to evaluate t-PA release. The stated rationale also relates t-PA release to flow mediated vasodilation, radial artery tonometry, and markers of endothelial function and oxidative stress. Those aims explain what the investigation sought to examine; they are not reported findings.
The record lists enrollment as 13, but the lost outcome data prevent interpreting that entry as the number of participants with analyzable primary endpoint measurements. The registry does not report how many observations were available for each endpoint, whether any measurements were excluded, or whether the missing endpoint data were lost for all or only part of the study. Those details are not reported in the registry record.
The design also limits the type of inference available. This is a single-group study, and the registry indicates that it is not a randomized comparison. The dose sequence is part of the intervention description, but the record does not describe a separate control group or provide a comparative estimate. A within-protocol observation would not, by itself, establish that bradykinin caused a difference in t-PA release or that any observed relationship generalizes beyond the study context.
The record lists secondary outcomes, but does not report numerical results for them. It therefore does not support conclusions about Peak FMD, Radial Artery Elasticity, lipid levels, PAI-1, CRP, F2 Isoprostanes, or other biomarkers. The registry's stated rationale that t-PA release is impaired in obese subjects should be read as background framing in the brief summary, not as a finding demonstrated by the posted outcome data.
Interpretation is further constrained by the lack of reported analysis details. The statistical model, handling of repeated dose measurements, treatment of missing observations, and any adjustment for multiple outcomes are not reported in the registry record. Without the endpoint values and analysis methods, neither effect magnitude nor statistical uncertainty can be assessed. The termination status is recorded, but its reason is not reported, so it should not be used to infer the study's results or operational history.
9. Statistical Methods Explained
The registry record identifies a single-group study and does not describe randomized allocation or masking. This matters because the design does not provide a randomized between-group contrast. The bradykinin dose sequence is described as part of a physiological protocol, but the presence of dose levels does not by itself make the study a randomized dose comparison. The record does not say whether dose order varied, whether measurements were analyzed as repeated observations, or what model was used.
What does a single-group design estimate?
In general, a single-group physiological study can describe measurements recorded under its protocol and examine patterns among those measurements. It does not automatically separate an intervention response from time effects, measurement variation, participant characteristics, or other influences. Randomization and a suitable comparator can help with some causal questions by making groups more comparable, but the registry record does not describe such a comparison for this study. Accordingly, the stated objective is best understood as mechanistic characterization and association, not a randomized treatment-effect estimate.
The protocol describes flow mediated vasodilation and radial artery tonometry, followed by intrabrachial bradykinin at 0, 10, 20, and 40 ng/100cc/min. It also describes strain gauge plethysmography and blood sampling at each dose for evaluating t-PA release. In general, measurements collected repeatedly during a protocol can be correlated within the same participant. An analysis that treats such observations as independent may misstate uncertainty; methods for repeated measures can account for within-participant dependence. Whether any such method was used is not reported in the registry record.
Why can variability affect inference?
General statistical interpretation depends on both the size of an estimated effect and its uncertainty. A confidence interval expresses a range of values compatible with the data and the analysis assumptions; a narrower interval generally indicates greater precision, while a wider interval indicates less precision. No confidence interval or other dispersion measure is reported for Peak t-PA Release. With the endpoint data lost, there is no posted estimate from which to assess precision.
In general, biological measurements can show more variability than a simple statistical model assumes. Over-dispersion means that observed variability exceeds what the assumed model anticipates. If present and not addressed, standard errors and inferential statements may be unreliable. The record does not report a model, residual checks, a dispersion assessment, or an approach to any over-dispersion. This is a general methodological consideration, not a claim that over-dispersion occurred in this study.
What do the endpoint details allow?
The endpoint is named Peak t-PA Release, and its timeframe is Single Study day. The registry does not specify the endpoint unit, a detailed rule for identifying the peak, or a numerical summary. In general, a peak measure depends on how sampling times and dose-related observations are combined or selected. Those operational details can affect interpretation and reproducibility. They are not reported in the registry record, so the meaning of “peak” cannot be refined beyond the endpoint label and protocol description.
The registry record lists enrollment as 13, but the primary endpoint population field says “Data was lost.” Enrollment and analyzable endpoint data are not interchangeable. General analysis reporting distinguishes the number enrolled from the number with observed outcome data and from the number included in a particular analysis. The record does not report endpoint-specific analysis populations, missingness patterns, exclusions, or an imputation method. No recalculated estimate can be produced from the posted primary endpoint information.
How should planning calculations be read?
In general, sample-size planning asks how many participants might be needed under specified assumptions to detect a chosen effect with a chosen error rate and power. Such figures are planning illustrations, not observed evidence and not “observed power.” A calculation based on an observed effect can be especially difficult to interpret if that effect is not available for verification. The registry record does not report the trial's own sample-size justification, and the lost endpoint data prevent readers from checking a primary observed effect against any planning illustration.
The statistical analysis plan, significance threshold, confidence interval method, handling of the dose sequence, and any planned covariate adjustment are not reported in the registry record. The record also does not report interim analyses. These omissions do not prove that such methods were absent from study conduct; they mean the registry record does not document them. For this study, the missing primary values are the limiting issue: statistical methods cannot recover an endpoint result that is not available in the record.
10. Multiplicity, Missing Data and Analysis Populations
The study lists a primary endpoint and several secondary outcomes. When analyses cover multiple outcomes or multiple comparisons, the chance of at least one apparently unusual result can increase. In general, multiplicity methods may be used to control that risk, or an analysis may identify a primary comparison and treat other findings as exploratory. Whether the study used any multiplicity adjustment, hierarchy, or prespecified distinction between confirmatory and exploratory analyses is not reported in the registry record.
The primary endpoint population field states “Data was lost.” The record does not explain which measurements were lost, when the loss occurred, whether it affected all participants or only some, or whether any recovery or imputation procedure was attempted. The endpoint-specific number of observations and the analysis population are not reported in the registry record. Enrollment is listed as 13, but that figure does not establish how many primary endpoint observations were available for analysis.
The record does not report a missing-data analysis, an imputation method, or sensitivity analyses. In general, missing data can affect estimates when the likelihood of a measurement being missing relates to its value or to participant characteristics. Without details on the pattern and handling of missingness, the direction or size of any such effect cannot be assessed. The registry also lists no numerical results for the secondary outcomes, so their completeness and analysis populations cannot be evaluated.
These limitations are distinct from multiplicity: the lost outcome data prevent interpretation of the primary endpoint, while absent analysis details prevent assessment of how the study planned to handle multiple outcomes. Neither issue can be resolved from the registry record.
11. What the Result Does, and Does Not, Mean
The registry record documents an intended investigation of t-PA release, vascular function, and related biomarkers in an obesity-related study context. It describes bradykinin administration and measurements intended to characterize t-PA release across the protocol. That information clarifies the scientific question and planned measurements.
It does not provide a numerical primary endpoint result. The primary endpoint field states “Data was lost,” and the record does not report values or uncertainty for Peak t-PA Release. Numerical results for the listed secondary outcomes are also not reported. Therefore, the posted record cannot establish the size, direction, or precision of any observed relationship among t-PA release, vascular function, and the biomarkers.
The brief summary's statement that t-PA release is impaired in obese subjects is part of the registry's rationale. It should not be mistaken for a result from the posted outcome data. Likewise, listing an outcome or a measurement procedure establishes that it was an intended focus of the study, not that a particular association or response was observed.
The record's single-group design also does not support a randomized comparison between bradykinin and a separate control group. The 0 dose is described in the dose sequence, but the record does not define it as a separate comparator arm. Consequently, the study description does not establish a comparative treatment effect.
The termination status is recorded, but the reason is not reported in the registry record. It cannot be used to infer whether results were favorable, unfavorable, inconclusive, or affected by operational difficulties. The appropriate conclusion is limited: the registry describes the study's question and procedures, while the primary result and the analysis details needed to assess it are unavailable.
12. Why This Trial Matters Statistically
This study matters statistically because it illustrates the difference between a clearly stated scientific question and an interpretable outcome result. The record names Peak t-PA Release as the primary endpoint and describes procedures intended to measure it, including blood sampling during the bradykinin dose sequence. Yet the endpoint population field reports that data were lost. Without endpoint values, a statistical analysis cannot establish the magnitude or precision of the primary result.
The record also illustrates why enrollment should not be treated as equivalent to endpoint completeness. Enrollment is listed as 13, but the number of usable primary endpoint observations is not reported. Statistical interpretation depends on knowing which participants and measurements contribute to an estimate, not simply the enrollment entry.
Another important distinction is between mechanistic characterization and randomized comparison. The registry describes a single-group study and does not identify a separate control arm. Associations among physiological measures may motivate further research, but they do not alone establish a causal effect. The protocol and outcome labels help define what was intended to be studied; they cannot substitute for a reported analysis.
Finally, the record lists multiple outcomes without reporting results or analysis details. Transparency about missing data, endpoint definitions, repeated measurements, and multiplicity helps readers judge whether findings are robust and how narrowly they should be interpreted. In this record, those details are not reported, so the statistical contribution that can be assessed is primarily the study's intended framework and the limits imposed by unavailable outcome data.
13. 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 direct limitation is that the primary endpoint data are recorded as lost. No numerical value, unit, or measure of variability is reported for Peak t-PA Release. As a result, the central endpoint cannot be evaluated for magnitude, direction, or precision. The record also does not report numerical results for the secondary outcomes, limiting assessment of the broader mechanistic aims.
The registry identifies enrollment as 13 but does not report how many participants had usable measurements for any outcome. It does not describe the extent or pattern of missing data, exclusions, or the analysis population. This prevents distinguishing a complete loss of the endpoint from partial missingness and prevents evaluating the possible consequences of missing observations.
The study is described as single-group, with allocation listed as NA and masking as NONE. No randomized control group is described. The dose sequence includes 0, 10, 20, and 40 ng/100cc/min, but its assignment and analysis procedures are not reported. The record does not specify whether dose order was fixed or varied, how the peak was defined, or how repeated measurements were modeled.
Further limitations are incomplete reporting of statistical methods and study conduct. The analysis plan, sample-size justification, interim analyses, multiplicity procedures, missing-data methods, and endpoint-specific populations are not reported in the registry record. The arm description is truncated after mentioning blood draws for other measures, so those procedural details are not fully available. The study is marked TERMINATED, but the reason is not reported. These gaps restrict interpretation without establishing why the data were lost or why the study ended.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Characterization of Brachial Arterial t-PA Release, Endothelial Function, Obesity and Inflammation — NCT00780481.
- Registry record last updated 2017-07-14; status last verified 2017-07.
- Results first posted 2017-07-14.
- 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.
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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
17. Record Summary
The registry record describes a single-group, unmasked study of bradykinin and vascular physiology in an obesity-related research context. It lists enrollment as 13, identifies Peak t-PA Release as the primary endpoint, and describes flow mediated vasodilation, radial artery tonometry, plethysmography, and blood sampling. The bradykinin dose sequence is 0, 10, 20, and 40 ng/100cc/min.
Secondary outcomes include Peak FMD, Radial Artery Elasticity, and biomarkers related to lipids, PAI-1, CRP, F2 Isoprostanes, inflammation, and obesity. The primary endpoint population field states “Data was lost,” and the record does not report numerical results for the primary or secondary outcomes. The study is marked TERMINATED; its reason for termination is not reported in the registry record. The design is not a randomized comparison, and statistical analysis details are not reported.