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 Function, Endothelin, and Inflammation in Pre-diabetic Obesity Versus Lean Healthy Controls (NCT00837590), a randomized phase 1 study. The primary outcome is Vascular Function.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00837590 |
| Phase | Phase 1 |
| Condition | Pre-diabetes, Obesity |
| Allocation | Randomized |
| Design model | Parallel |
| 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 study concerns people with pre-diabetes and obesity, alongside lean healthy controls. The acute arm description refers to nondiabetic lean and obese subjects; the chronic arms describe obese and lean subjects separately. The registry record does not report the detailed eligibility criteria, how pre-diabetes was defined, or the baseline characteristics of participants.
Intervention
The interventions are described as acute and chronic salsalate. The acute assessment compares vascular function at baseline and after a single oral dose. The chronic assessments compare baseline with measurements after 2 months' treatment with oral salsalate. The chronic lean arm also includes an acute fatty acid infusion to assess vascular function on both occasions. The registry record does not report dose details.
Comparator
The record describes comparisons over time within treatment arms and includes lean and obese groups. It does not identify a placebo or untreated control arm in the available arm descriptions. Although the study allocation is recorded as randomized, the registry record does not explain what was randomized, how allocation was performed, or whether a particular group served as the randomized comparator.
Primary question
The listed primary endpoint is vascular function, with flow-mediated vasodilation identified as the primary endpoint of interest. The study aims ask whether inflammation contributes to vascular and metabolic dysfunction in pre-diabetic obesity and whether anti-inflammatory strategies have benefits in the context of existing metformin or lisinopril treatment. The registry record does not report results that answer those questions.
3. Trial Design
The registry record describes a phase 1, randomized, unmasked, parallel study sponsored by Indiana University. Enrollment is listed as 16. The study began in 2009-03, with primary completion in 2010-06, and its status is terminated. The record does not explain why the study was terminated or whether enrollment reached the listed total.
Three arm descriptions distinguish an acute salsalate assessment from chronic assessments in obese and lean participants. In the acute arm, nondiabetic lean and obese subjects were to be measured at baseline and after a single oral dose. In the chronic obese arm, measurements were to be made at baseline and after 2 months' treatment. The chronic lean arm has the same treatment interval and also includes an acute fatty acid infusion during vascular function measurements on both occasions.
These descriptions indicate that the planned measurements include within-participant comparisons over time. The presence of lean and obese groups also permits comparisons between participant categories in principle, but the record does not state which comparisons were prespecified or how the randomized parallel allocation related to these groups. It does not provide a flow diagram, the number enrolled in each arm, or the number completing each assessment.
The record labels the study a pilot and says the primary outcome population includes all participants completing treatment. This does not establish how many participants completed treatment or whether all recorded participants contributed endpoint data. The allocation procedure, concealment, treatment adherence assessment, and detailed analysis plan are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: Subjects were excluded primarily for anemia based on screening labs or failure to return for clinic visits.
Overall Study
| Stage | Acute Salsalate | Chronic Salsalate - Obese | Chronic Salsalate - Lean |
|---|---|---|---|
| STARTED | 6 | 5 | 5 |
| COMPLETED | 6 | 4 | 4 |
| NOT COMPLETED | 0 | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: Pilot study. Analyzing data from all participants completing treatment.
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 | Acute Salsalate | Chronic Salsalate - Lean | Chronic Salsalate - Obese | Total |
|---|---|---|---|---|---|
| Participants analysed | 6 | 5 | 5 | 16 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 6 | 5 | 5 | 16 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 2 | 2 | 2 | 6 |
| Sex: Female, Male: Male | Participants | 4 | 3 | 3 | 10 |
| Region of Enrollment: United States | participants | 6 | 5 | 5 | 16 |
6. Primary Endpoint
The registry lists the primary outcome as Vascular Function, measured over Measured at baseline and after a single oral dose of salsalate (Acute) or 2 months' treatment with salsalate (Chronic).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ml/min |
| Endpoint classification | Continuous Endpoint |
The primary outcome is titled vascular function, measured in ml/min, and described as a mean with standard deviation. The primary endpoint of interest is flow-mediated vasodilation. This is a measure of change in vessel diameter or blood flow in response to a stimulus that increases flow; as a general statistical and physiological concept, it is used to characterize endothelial-dependent vascular function. The registry record does not give further measurement details, such as the exact procedure, timing, or operational definition used to derive the recorded value.
The stated assessment times are baseline and after a single oral dose for the acute assessment, or after 2 months' treatment for the chronic assessment. The lean chronic arm additionally includes measurements around an acute fatty acid infusion. These repeated measurements can describe change over time within participants, while group comparisons may address whether patterns differ between participant categories or study arms. The record does not specify the primary contrast or explain how the infusion measurements contribute to the primary endpoint analysis.
A continuous endpoint can retain information about the size and direction of measured differences rather than reducing observations to categories. A mean describes the central value, and a standard deviation describes variation among observations. These summaries alone do not establish a treatment effect: interpretation also depends on the comparison, the number of observations contributing data, uncertainty around estimates, and the analysis method. The registry record lists the endpoint but does not post numerical endpoint results, standard deviations, confidence intervals, or an analysis estimate.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a biologically focused pilot study, not a completed efficacy analysis with posted estimates. It lists flow-mediated vasodilation as the primary endpoint of interest and describes measurements before and after acute or chronic salsalate exposure. However, it reports no primary outcome analysis, no group means, no changes from baseline, and no uncertainty estimates. Consequently, the posted record does not show the direction or magnitude of any vascular-function change.
The record’s study aims raise questions about inflammation, vascular and metabolic dysfunction, and anti-inflammatory strategies in the context of metformin or lisinopril. Those aims should not be confused with findings. The intervention descriptions identify salsalate assessments, but the record does not report whether participants were receiving metformin or lisinopril, how those treatments were handled, or results for either treatment context. It therefore cannot establish whether inflammation contributed to dysfunction or whether any anti-inflammatory strategy altered vascular or metabolic measures.
Enrollment is listed as 16, and the primary outcome population is described as participants completing treatment. This enrollment figure alone does not establish the number included in the endpoint analysis. The record does not report the number completing each arm or the number with usable measurements at each time point. In a small pilot, estimates can be imprecise, but the uncertainty cannot be quantified because outcome estimates and confidence intervals are absent. The record’s status is terminated; that status does not, by itself, explain why the study ended or what results were obtained.
The safety entries list no serious adverse events, other adverse events, or deaths in the groups shown. Those entries are counts in the registry record, not an analysis of comparative risk. The number at risk is listed separately by group, and the modest group counts mean that an absence of recorded events should be read as a description of the posted observations, not proof that events cannot occur.
Overall, the available record establishes the study’s stated endpoint, treatment schedules, broad design labels, and recorded safety counts. It does not provide the clinical outcome results needed to estimate the effect of salsalate on flow-mediated vasodilation. No conclusion about the presence, absence, size, or precision of an effect can be drawn from an outcome analysis that is not reported in the registry record.
9. Statistical Methods Explained
What does the endpoint summary represent?
The primary outcome is continuous and is described using a mean and standard deviation. As a general explanation, the mean locates the center of a set of measurements, while the standard deviation describes how dispersed individual measurements are around that center. A mean is not a complete account of the data: it does not show the distribution’s shape, whether there are unusual values, or how precisely the mean has been estimated. The registry record does not report endpoint values or standard deviations, so those features cannot be assessed for this study.
Flow-mediated vasodilation is the named primary endpoint of interest, with the outcome title giving ml/min as the unit. The record does not give enough measurement detail to determine how the named endpoint was translated into that unit, or whether the unit refers to the endpoint itself or a related flow measure. No clarification should be inferred from the title alone.
How do repeated measurements affect interpretation?
Measurements at baseline and after treatment create a paired structure when the same participant contributes data at both times. In general, paired analysis accounts for the fact that two measurements from one participant are related. A change-from-baseline analysis, a model of measurements over time, and a comparison of follow-up values can answer different questions and can yield different estimates. The registry record does not identify which method was used, whether baseline values were included as covariates, or how incomplete pairs were handled.
The design also includes distinct acute and chronic schedules, with lean and obese participant categories. These are not automatically interchangeable comparisons: an acute response to a single dose and a response after 2 months' treatment address different time scales. The acute fatty acid infusion in the chronic lean arm adds another measurement condition. The record does not state the planned contrasts among these assessments or how the infusion condition was incorporated into analysis.
What can randomization tell the reader?
Randomization can, in general, reduce systematic differences between assigned groups when implemented appropriately. The study is labeled randomized, but the registry record does not explain the allocation sequence, concealment, unit of randomization, or which arms or conditions were randomized. It also records masking as none. These labels are useful design descriptors, but they do not supply enough information to reconstruct the assignment process or determine the extent to which group comparisons are protected from bias.
The parallel model indicates that the record classifies the study as a parallel design. The arm descriptions nevertheless include baseline and follow-up measurements within arms. Repeated measurements within an arm do not by themselves specify a randomized control comparison. The record does not describe a placebo arm or a no-treatment group in the arm information available, so the role of any control condition is not reported in the registry record.
What do confidence intervals and significance tests mean?
In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the analysis. Its width conveys precision: wider intervals indicate less precise estimates, while narrower intervals indicate greater precision. A significance test evaluates compatibility between observed data and a specified null hypothesis under a statistical model. Neither a confidence interval nor a p-value replaces consideration of the estimate’s size, design, measurement quality, and clinical context.
No endpoint estimate, confidence interval, or p-value is posted in the registry record. The record therefore supports no numerical assessment of statistical significance or precision for vascular function. The same limitation applies to any proposed comparison of lean and obese participants or of acute and chronic assessment results.
How should the planning illustration be understood?
The planning assumptions describe an illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is framed as a stated fraction of the observed effect. Such an illustration is a planning exercise, not a report of participants observed in an analysis and not a measure of the study’s observed power. The registry record does not report the numerical planning outputs or the underlying observed effect used for that illustration.
In general, planning calculations depend on assumptions about the effect size, variability, allocation, and analysis. If those assumptions differ from the study actually conducted, the resulting illustration may not reflect its design. The record does not report the original sample-size justification or state that the planning assumptions were used to choose enrollment. The listed enrollment of 16 should therefore be read as an enrollment figure, not as evidence that the study had adequate power for a particular effect.
Why does variation matter?
For continuous outcomes, participant measurements can vary for biological, measurement, and other reasons. In general, greater variability makes it harder to distinguish a systematic difference from random fluctuation at a fixed sample size. If variation is not adequately described, the precision of a mean difference cannot be judged. For count outcomes, over-dispersion means observed variation exceeds what a simple model assumes; this can make standard errors too small if ignored. That concept is general and is not evidence that over-dispersion occurred in this study. The registry record does not post outcome data that would permit assessment of variability or model fit.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one outcome measure and no analyses. It does not report a complete analysis plan, a hierarchy of endpoints, or a plan for handling multiple comparisons. The study descriptions include acute and chronic schedules, lean and obese categories, baseline and post-treatment measurements, and an infusion condition in the chronic lean arm. These features could produce several possible comparisons, but the record does not establish which were prespecified or how multiplicity was addressed. No adjustment method or testing hierarchy is reported in the registry record.
Missing-data handling is also not reported in the registry record. The primary outcome population is described as all participants completing treatment, but the record does not give the number completing treatment, define completion, or state how participants with incomplete measurement sets were treated. It does not say whether missing endpoint values were excluded, imputed, or handled in a repeated-measures model. Because the number with observations at each time point is not posted, the extent and pattern of missingness cannot be evaluated.
The record does not describe an intention-to-treat population or another analysis population beyond its statement about participants completing treatment. It does not report whether randomized participants were analyzed according to assignment, whether participants who stopped treatment remained in analyses, or how protocol deviations were managed. These omissions limit evaluation of the analysis population and the risk that the available results, if any, might differ from results among all enrolled participants. With no outcome analyses posted, the impact of multiplicity or missing data on an estimated treatment effect cannot be assessed.
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 |
|---|---|---|---|
| Acute Salsalate | 0 | 6 | 0.0% |
| Chronic Salsalate - Obese | 0 | 5 | 0.0% |
| Chronic Salsalate - Lean | 0 | 5 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Acute Salsalate | 0 of 6 |
| Chronic Salsalate - Obese | 0 of 5 |
| Chronic Salsalate - Lean | 0 of 5 |
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 |
|---|---|
| Acute Salsalate | 0 of 6 |
| Chronic Salsalate - Obese | 0 of 5 |
| Chronic Salsalate - Lean | 0 of 5 |
The registry record lists serious adverse events, other adverse events, and deaths by group. For Acute Salsalate, 6 were at risk for serious adverse events and 6 for other adverse events; the corresponding affected counts are 0 and 0, with 0 deaths. For Chronic Salsalate - Obese, 5 were at risk for each adverse-event category, with 0 affected in each category and 0 deaths. For Chronic Salsalate - Lean, 5 were at risk for each category, with 0 affected in each category and 0 deaths.
These are recorded counts, not proof of zero risk. As a general point, a group with no recorded events can still be compatible with a range of underlying event risks, especially when the number observed is limited. The record does not provide event descriptions, follow-up time for safety, definitions of the adverse-event categories, or a comparative safety analysis. The absence of listed serious-event terms is consistent with the reported serious-event counts, but does not establish that every possible event was assessed or reported. These figures should be read as the safety information posted in the registry record, not as a conclusion about treatment safety.
12. What the Result Does, and Does Not, Mean
The record describes a pilot investigation of vascular function in pre-diabetic obesity and lean controls, with acute and chronic salsalate assessments. It identifies flow-mediated vasodilation as the primary endpoint of interest and gives the broad measurement schedule. These details clarify the scientific questions and the kind of outcome the investigators intended to examine.
The posted record does not include analyzed vascular-function results. It therefore does not show whether measurements increased, decreased, or stayed similar after salsalate, nor whether any patterns differed between lean and obese participants. It also does not provide results addressing inflammation, metabolic dysfunction, or the contexts of metformin and lisinopril mentioned in the study aims. The stated aims are questions, not evidence that those questions were answered.
Enrollment of 16 and the group-specific safety counts describe the scale and recorded events in the registry entry. They do not establish the number of participants contributing outcome data or the precision of any effect estimate. The absence of posted estimates, confidence intervals, and analyses means the magnitude and uncertainty of any vascular-function difference cannot be assessed. The terminated status supplies no explanation of why the study ended and should not be treated as a result.
In general, a pilot study can help characterize feasibility, measurement procedures, or preliminary patterns, but the label alone does not establish what the study accomplished. Here, the registry record does not report feasibility outcomes, an analysis of the primary endpoint, or a rationale for termination. Accordingly, the record can support a description of the intended design and the information posted, but not a conclusion that salsalate did or did not affect vascular function. It also cannot establish whether an observed difference, if one occurred, would be clinically important.
13. Why This Trial Matters Statistically
This study is statistically noteworthy because its questions span distinct time frames and participant categories. An acute assessment after a single oral dose and a chronic assessment after 2 months' treatment do not represent the same estimand: they concern responses over different exposure periods. The lean and obese groups also make the choice of comparison important. Clear identification of the primary contrast would be needed to interpret any estimate, but that contrast is not reported in the registry record.
The repeated baseline and follow-up measurements create opportunities to use within-participant information. In general, such designs can account for stable differences between participants, but the analysis must reflect the paired structure and clarify how missing follow-up observations are handled. The registry record identifies the measurement schedule without reporting the analysis method or the amount of complete data.
The pilot designation and listed enrollment of 16 also underscore why precision is important. A numerical estimate without an uncertainty measure could be misleading, and an absence of statistical significance would not by itself show that an effect is absent. The posted registry record contains no outcome estimate or confidence interval, so neither the direction nor the precision of a vascular-function result can be evaluated.
Finally, a record can describe a scientific aim and planned endpoint without reporting a result. Keeping those elements separate prevents the study rationale from being mistaken for evidence. The available entry documents the questions, arm descriptions, and safety counts, while leaving the primary outcome analysis and several design details unreported. That distinction is central to statistically responsible interpretation.
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 outcome information is the main limitation for interpretation: the registry record identifies the primary endpoint but posts no analysis estimates, group summaries, confidence intervals, or p-values. As a result, the size, direction, and precision of any measured change cannot be described. The record also does not identify the specific primary comparison, which matters because the study includes acute and chronic assessments and lean and obese categories.
Important design details are not reported in the registry record. These include the exact randomization procedure and target of allocation, the role of any control condition, treatment dose, detailed eligibility criteria, baseline participant characteristics, and the number assigned to and completing each arm. The record labels the study unmasked and parallel but does not explain how those design features were implemented across the described assessment schedules.
The outcome measurement description is limited. Flow-mediated vasodilation is named as the primary endpoint of interest, and the outcome title gives ml/min, but the operational definition and measurement procedure are not reported. The record does not state how the fatty acid infusion condition relates to the primary endpoint analysis.
Analysis details, including handling of repeated measurements, missing data, multiplicity, and analysis populations, are not reported. The status is terminated, but the reason is not reported in the registry record. The posted safety counts are small and lack event definitions and comparative analysis. These gaps constrain interpretation of both efficacy-related outcomes and safety; they should not be filled by assumptions about the original protocol or conduct.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Vascular Function, Endothelin, and Inflammation in Pre-diabetic Obesity Versus Lean Healthy Controls — NCT00837590.
- Registry record last updated 2019-08-01; status last verified 2013-05.
- Results first posted 2019-08-01.
- 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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18. Record Summary
NCT00837590 is a phase 1, randomized, unmasked, parallel pilot study sponsored by Indiana University, with enrollment listed as 16 and status recorded as terminated. It concerns vascular function in pre-diabetic obesity compared with lean healthy controls and describes acute and chronic salsalate assessments.
The primary endpoint of interest is flow-mediated vasodilation, measured at baseline and after a single oral dose or 2 months' treatment, depending on the arm. The registry record does not report primary outcome analyses, treatment-effect estimates, or uncertainty intervals. Safety entries list no serious adverse events, other adverse events, or deaths in the groups recorded. Reasons for termination, detailed allocation procedures, analysis methods, and missing-data handling are not reported in the registry record.