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 Unacylated Ghrelin to Improve FuncTioning in PAD: The GIFT Trial (NCT03358355), a na phase 1, phase 2 study. The primary outcome is Levels of Unacylated Ghrelin.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03358355 |
| Phase | Phase 1, Phase 2 |
| Condition | Peripheral Artery Disease, PAD, Peripheral Arterial Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 9 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Northwestern University |
| Results posted | Yes |
2. Clinical Question
Population
Older people with peripheral artery disease (PAD) who received an injection and had data available contributed to the primary outcome population. The registry record lists enrollment of 9, but does not report the number contributing data at each dose or time point.
Intervention
Subcutaneous unacylated ghrelin was given at doses of 10 ug/kg, 20 ug/kg, and 40 ug/kg. The study is described as a pilot investigating dose and safety.
Comparator
No separate control or comparator group is reported. The record describes a single-group model and no randomized comparison, so the dose groups should not be read as a like-for-like controlled comparison.
Primary question
The primary outcome concerns levels of unacylated ghrelin measured before and after every injection, at baseline and scheduled intervals up to 24 hours after baseline. The registry record does not report the observed levels or analyses needed to determine how they varied.
In practical terms, the study asks whether the administered compound can be assessed across the stated dose levels by measuring its level in participants after injection, while also recording safety. It does not set out, in the information reported, a controlled test of whether ghrelin changes PAD symptoms, function, or clinical outcomes. Brachial artery flow-mediated dilation (FMD) is listed as a secondary outcome, but its results are not reported in the registry record.
Because the record gives no primary outcome values, it is not possible to describe the size or direction of any measured change, compare levels across the dose groups, or assess the precision of an estimated response. The stated question and design are therefore best understood as exploratory rather than as evidence from a controlled treatment comparison.
3. Trial Design
GIFT is a phase 1 and phase 2 pilot trial sponsored by Northwestern University. Its registry record describes a single-group model, with no masking and allocation recorded as NA. The study status is completed. The record lists a start date of 2016-06-07 and a primary completion date of 2017-08-30, with enrollment of 9.
The intervention was subcutaneous unacylated ghrelin. The intervention description lists doses of 10 ug/kg, 20 ug/kg, and 40 ug/kg. The brief summary says that the pilot would investigate the optimal subcutaneous dose and safety in older people with PAD. The record does not report how participants were assigned to the dose levels, how long each participant was followed beyond the primary outcome timeframe, or whether participants received more than one dose. Those details should not be inferred from the dose descriptions.
This is not a randomized comparison, and the registry record does not identify a control group. Consequently, the listed dose groups do not provide a controlled estimate of what would have happened without the intervention. Differences between people or measurements across dose groups could not be separated from dose effects using a randomized between-group comparison, because such a comparison is not reported.
The primary outcome is continuous: levels of unacylated ghrelin, expressed in pg/ml, summarized as a mean with standard deviation. Measurements are described as occurring before and after every injection, at baseline and scheduled intervals up to 24 hours after baseline. The population is defined as participants who received the injection and had data available. The record also lists brachial artery FMD as a secondary outcome, and reports four outcome measures overall, but further outcome details are not reported in the registry record.
The registry record does not report a protocol-level statistical plan, a sample-size justification, or details of dose assignment. The planning assumptions included in the record are not evidence that those assumptions determined the trial's enrollment or analysis.
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 | Unacylated Ghrelin Intervention |
|---|---|
| STARTED | 9 |
| COMPLETED | 9 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Data originate from participants that received the injection and of which had data available
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 | Intervention |
|---|---|---|
| Participants analysed | 9 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 |
| Age, Categorical: >=65 years | Participants | 9 |
| Age, Continuous | years | 71.0 (SD 4.7) |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 8 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 9 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 3 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 6 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 9 |
| Ankle-Brachial Index (ABI) | ratio | 0.69 (SD 0.13) |
| Body Mass Index (BMI) | kg/m^2 | 30.4 (SD 4.6) |
| Six-minute walk distance | feet | 1254.6 (SD 531.8) |
6. Primary Endpoint
The registry lists the primary outcome as Levels of Unacylated Ghrelin, measured over Baseline and at scheduled intervals up to 24 hours after baseline.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | pg/ml |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the level of unacylated ghrelin, measured in pg/ml. The record describes measurements before and after every injection, at baseline and scheduled intervals up to 24 hours after baseline. It specifies a mean and standard deviation as the summary statistics, and limits the outcome population to participants who received the injection and had data available.
As a general statistical concept, measuring the level of a compound after administration can describe exposure over the scheduled measurement period. Repeated measurements can also show how observed levels vary over time within the recorded schedule. The mean describes the average level in the analyzed observations, while the standard deviation describes the spread of those observations around the mean. The standard deviation is not a measure of how precisely the mean has been estimated; a confidence interval would address uncertainty in an estimate, but one is not reported in the registry record.
This endpoint is distinct from a clinical outcome such as function or symptoms. It characterizes measured ghrelin levels; by itself it does not establish a change in PAD, demonstrate a functional benefit, or identify a preferred dose. Those interpretations would require relevant outcome results and an appropriate analysis, neither of which is reported for the primary endpoint. Although brachial artery FMD is listed as a secondary outcome, its role and results are not described in further detail in the registry record.
No observed means, standard deviations, or other primary outcome values are reported in the registry record. It is therefore not possible to summarize the measured levels, their variability, or any pattern across the scheduled measurements.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a completed pilot study with a defined primary measurement and three dose levels, but it does not report the primary outcome values or analyses. In particular, it provides no mean ghrelin levels, standard deviations, estimated changes, confidence intervals, or statistical tests. The numerical outcome effect and its precision therefore cannot be assessed from the record.
The primary endpoint is measured before and after injections at baseline and scheduled intervals up to 24 hours after baseline. That schedule describes what was intended to be measured; it does not establish that every scheduled measurement was available for every participant. The record defines the analysis population as participants who received an injection and had data available, but does not report how many observations were available at each time point or how missing measurements were handled.
The record also does not provide a controlled comparator. It describes a single-group study with allocation recorded as NA and identifies that the study is not a randomized comparison. The dose levels should therefore not be treated as if they were arms in a randomized trial. Without reported assignment details, outcome results, and a suitable comparison, the record cannot support a causal interpretation of differences associated with dose.
Safety is described separately through adverse-event figures. The record lists serious events and other adverse events for the dose groups, along with deaths and a serious-event term. These figures are descriptive registry entries. They do not, on their own, show whether an event was caused by the intervention, and the record does not provide enough information to assess comparative risk or uncertainty around these counts.
Phase 1 and phase 2 status and the pilot description indicate an exploratory study context, but they do not substitute for outcome data or a reported analysis. The registry record does not state a sample-size justification or a statistical analysis plan. It also reports zero analyses. Accordingly, no conclusion about a dose response, treatment effect, clinical benefit, or lack of effect can be drawn from the primary endpoint information recorded.
Any sample-size illustrations associated with the record are planning calculations, not observed trial findings. The stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and detection of a stated fraction of the observed effect. The record's single-group design is not a two-arm randomized comparison, and numerical planning results are not reported in the registry record for this analysis. Such illustrations should not be mistaken for the trial's own design rationale or for evidence of observed power.
9. Statistical Methods Explained
What does the primary summary describe?
The primary measure is continuous: levels of unacylated ghrelin in pg/ml. The registry specifies a mean and standard deviation. In general, a mean summarizes the center of a set of measurements, while the standard deviation describes how dispersed individual measurements are around that center. They answer different questions: the mean concerns the average level, and the standard deviation concerns variability among observations.
A standard deviation is not the uncertainty interval for the mean. A confidence interval is a general statistical method for expressing uncertainty about an estimated quantity, such as a mean or a difference. No confidence interval is reported for the primary outcome in the registry record. Nor are the observed means or standard deviations reported, so neither the central values nor the observed spread can be interpreted.
Why does the measurement schedule matter?
The record describes baseline measurement and scheduled measurements up to 24 hours after baseline, including measurements before and after every injection. Repeated measurements taken from the same participant are generally related rather than independent. As a general statistical principle, analyses of repeated measurements should account for that within-participant relationship; treating all measurements as independent can give misleading uncertainty estimates. The registry record does not report the model or method used to analyze repeated measurements, or whether such an analysis was conducted.
It is also important to distinguish a schedule from completeness. A stated measurement plan does not show how many measurements were actually collected at each scheduled time. The primary population includes participants who received the injection and had data available. The record does not report the number of missing values, their timing or reasons, or any method for handling them.
What would a dose comparison require?
The intervention description lists 10 ug/kg, 20 ug/kg, and 40 ug/kg. Those are dose levels, not evidence of a randomized comparison. The record describes a single-group model, allocation as NA, and no randomized comparison. It does not report how participants came to receive a dose or whether the same participants received multiple doses. Consequently, a reader cannot assume that a difference between recorded dose groups is attributable to dose.
For a controlled estimate, a comparison needs a defined comparator and an analysis that reflects the assignment and measurement structure. Neither a separate control group nor a comparative primary analysis is reported. The record also does not report a statistical model for estimating change over time or differences among dose levels. Any statistical explanation of what such a model might do would be general, not a description of the method used in this trial.
How should uncertainty and planning be understood?
In general, a confidence interval communicates the range of values compatible with an estimate under the model and assumptions used. A p-value, when reported, addresses compatibility of data with a specified null hypothesis under an analysis; it does not measure the probability that a treatment works. Neither a primary endpoint confidence interval nor a primary endpoint p-value is reported in the registry record. No inferential result can therefore be reconstructed from the outcome description alone.
The registry record includes sample-size assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. It says that non-time-to-event planning figures are participants per arm, while time-to-event figures are total events. These are planning assumptions, not the reported design of this single-group trial. The numerical illustration results are not included in the registry record for this analysis, and no observed power should be inferred from them. The record does not report the trial's own sample-size justification.
Why can over-dispersion matter?
As a general concept, over-dispersion occurs when observed variability exceeds what a statistical model assumes. If a model underestimates variability, its uncertainty estimates can be too narrow and tests can appear more conclusive than warranted. The primary measure is continuous and summarized by a mean and standard deviation, but the registry record does not report a model or enough outcome data to assess whether over-dispersion was relevant. No claim that it occurred in this trial is justified.
What can be concluded from the listed analysis status?
The record lists zero analyses. This is not equivalent to evidence that a particular effect was absent; it means that analysis results are not recorded in the information available for this account. The record lists four outcome measures, but the detailed results and analysis methods needed to interpret them are not reported. Statistical interpretation must therefore remain at the level of design, endpoint definition, and descriptive safety figures.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists four outcome measures, identifies levels of unacylated ghrelin as the primary outcome, and names brachial artery FMD as a secondary outcome. It does not report how many time points or comparisons were included in the intended primary analysis, whether separate tests were planned for each dose or time, or whether a prespecified hierarchy or multiplicity adjustment was used. A multiplicity plan is therefore not reported in the registry record.
As a general statistical matter, evaluating multiple outcomes, times, or comparisons can increase the chance of obtaining apparently notable results by chance if each is tested independently. Prespecification and suitable methods can help control that issue. This general concern cannot be quantified for this trial because the registry record does not give the analysis plan or results.
The primary outcome population is defined as participants who received an injection and had data available. This definition does not state how many participants or measurements were excluded for missing data. Reasons for missingness, methods for handling incomplete repeated measurements, imputation, and sensitivity analyses are not reported in the registry record. The record therefore does not establish whether missing data could have influenced the reported outcome; it does not include outcome analyses with which to assess that possibility.
The registry record reports zero analyses. It does not describe an intention-to-treat population, a per-protocol population, or other analysis populations beyond the available-data description for the primary measure. Interim analyses, stopping rules, and any prespecified statistical analysis plan are also not reported in the registry record. These omissions limit assessment of how outcomes and analysis choices were specified, but they do not prove that a particular method was or was not used outside the 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 |
|---|---|---|---|
| Intervention(10 ug/kg) | 1 | 6 | 16.7% |
| Intervention(20 ug/kg) | 0 | 6 | 0.0% |
| Intervention(40 ug/kg) | 0 | 6 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Intervention(10 ug/kg) | 0 of 6 |
| Intervention(20 ug/kg) | 0 of 6 |
| Intervention(40 ug/kg) | 0 of 6 |
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 |
|---|---|
| Intervention(10 ug/kg) | 0 of 6 |
| Intervention(20 ug/kg) | 1 of 6 |
| Intervention(40 ug/kg) | 0 of 6 |
Most frequent serious adverse event terms
| Event term | Organ system | Intervention(10 ug/kg) | Intervention(20 ug/kg) | Intervention(40 ug/kg) |
|---|---|---|---|---|
| Cardiovascular event | Cardiac disorders | 1 of 6 | 0 of 6 | 0 of 6 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Intervention(10 ug/kg) | Intervention(20 ug/kg) | Intervention(40 ug/kg) |
|---|---|---|---|---|
| New lightheadedness or dizziness | General disorders | 0 of 6 | 1 of 6 | 0 of 6 |
| New headaches | General disorders | 0 of 6 | 1 of 6 | 0 of 6 |
| New symptoms | General disorders | 0 of 6 | 1 of 6 | 0 of 6 |
| New swelling | General disorders | 0 of 6 | 0 of 6 | 0 of 6 |
Serious events with the highest arm-level rate: cardiovascular event (16.7%).
The registry lists serious adverse-event figures separately for the three intervention dose groups. For 10 ug/kg, 1 serious adverse event was listed among 6 at risk; for 20 ug/kg and 40 ug/kg, 0 serious adverse events were listed among 6 at risk in each group. Deaths were listed as 0 in each group. The record also lists other, non-serious adverse events: 0 among 6 at risk for 10 ug/kg, 1 among 6 at risk for 20 ug/kg, and 0 among 6 at risk for 40 ug/kg.
The serious-event term listed is “Cardiovascular event” at 16.7%. The record does not give further detail about the event, its timing, severity beyond its serious classification, or its relationship to the intervention. The term and percentage should be read as registry descriptions, not as proof of causation or as a dose-specific rate.
These figures are descriptive counts, not a controlled estimate of comparative safety. The record does not report a comparator group or provide uncertainty estimates for the event figures. It also does not explain whether the listed at-risk denominators correspond to the same participants across dose groups or how events were attributed if participants received more than one dose. The counts should not be added across groups or interpreted as a randomized dose comparison.
With a pilot study and sparse event counts, the absence of a listed event in a group does not establish that an event cannot occur. Conversely, a listed event does not establish that the intervention caused it. The registry record does not report a causal assessment.
12. What the Result Does, and Does Not, Mean
The GIFT registry record documents a completed pilot study of subcutaneous unacylated ghrelin in older people with PAD. It specifies three dose levels and a primary measure of ghrelin levels assessed before and after injection, from baseline through scheduled intervals up to 24 hours after baseline. It also lists a safety focus and brachial artery FMD as a secondary outcome.
Those design details explain what the study set out to examine, but the primary outcome values and analyses are not reported in the registry record. No observed mean levels, standard deviations, changes, confidence intervals, or statistical tests are available in the record. It is therefore not possible to say what levels were observed, how they varied over time, or whether they differed across doses.
The design also does not provide a reported randomized control comparison. The registry identifies a single-group model, allocation as NA, and no randomized comparison. Even if outcome differences among dose groups had been reported, this design description would not justify treating them as causal dose effects without further information about assignment and analysis. The record does not report those details.
The safety entries are likewise limited. They give counts by dose group and identify a serious-event term, but do not establish that the intervention caused any event or permit a controlled comparison. The available information should not be read as a conclusion that the intervention is safe or unsafe.
Overall, the record supports a description of the study's intended measurements, design, and recorded adverse-event figures. It does not support a conclusion about clinical benefit, lack of benefit, an optimal dose, or a dose response. Such conclusions would require outcome results and analyses that are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically instructive because its endpoint and design need to be kept distinct. Measuring levels of unacylated ghrelin after injection is a way to describe the measured compound over the scheduled period. It is not, by itself, a measure of improvement in PAD. The registry record separately lists brachial artery FMD as a secondary outcome, but does not report its results.
The study is described as a single-group pilot with three dose levels, rather than a randomized comparison with a control group. That distinction affects what can be inferred: a set of dose descriptions does not automatically create a valid comparative experiment. Assignment details, a defined comparator, and an appropriate analysis would be needed to interpret group differences as effects of dose, and those details are not reported in the registry record.
The record also illustrates why endpoint results and analysis details matter alongside a protocol description. Means and standard deviations could characterize the primary outcome, while uncertainty estimates and a suitable repeated-measures analysis could help convey how precise and interpretable those estimates are. The registry record supplies the endpoint definition but not its observed values, uncertainty, or analysis results.
Finally, the event counts show why descriptive safety entries should not be mistaken for causal evidence. With no reported controlled comparison and no detailed event assessment, the counts are a record of what was listed, not an estimate of comparative risk. The value of examining this trial statistically lies in recognizing the boundary between a useful pilot question and conclusions that the available results cannot establish.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
Several limitations are specific to what the registry record reports for this trial. The most consequential is that it defines the primary endpoint but does not report primary outcome values or analyses. The stated mean and standard deviation format cannot be interpreted without the observed summaries, and no estimate of precision is available.
The study is described as a single-group model with no randomized comparison and no separate comparator reported. The record does not describe how participants were assigned to 10 ug/kg, 20 ug/kg, or 40 ug/kg, whether exposure to more than one dose occurred, or how any such structure was handled analytically. This restricts interpretation of differences between dose descriptions.
The outcome population is limited to participants who received an injection and had data available. The record does not report the number of observations available at each scheduled time, the reasons for missing measurements, or methods for handling them. Because the primary schedule includes measurements up to 24 hours after baseline, completeness over time is relevant, but cannot be assessed from the information reported.
The record lists enrollment of 9 and safety denominators of 6 at risk for each dose group, but does not explain the relationship between these figures or give further detail about exposure and follow-up by participant. No sample-size justification or statistical analysis plan is reported in the registry record. Nor are details of multiplicity control, interim analyses, or analysis populations reported.
These limitations concern the information available in the registry record. They should not be taken as proof that unreported procedures were not performed; their details are simply not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Unacylated Ghrelin to Improve FuncTioning in PAD: The GIFT Trial — NCT03358355.
- Registry record last updated 2020-03-12; status last verified 2020-02.
- Results first posted 2020-03-12.
- 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
NCT03358355, titled “Unacylated Ghrelin to Improve FuncTioning in PAD: The GIFT Trial,” is listed as a completed phase 1 and phase 2 pilot trial sponsored by Northwestern University. The record describes a single-group model, no masking, and allocation recorded as NA. Enrollment is 9. The listed start date is 2016-06-07, and the primary completion date is 2017-08-30.
The intervention is subcutaneous unacylated ghrelin at doses of 10 ug/kg, 20 ug/kg, and 40 ug/kg. The primary outcome is unacylated ghrelin levels in pg/ml, summarized by mean and standard deviation, with measurements before and after every injection at baseline and scheduled intervals up to 24 hours after baseline. Brachial artery FMD is listed as a secondary outcome.
The record lists four outcome measures and zero analyses. Primary outcome values and analyses are not reported in the registry record. Safety entries list serious and other adverse events by dose group and 0 deaths in each group. These entries are descriptive and do not provide a controlled comparison.