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 Angiotensin II in the Perioperative Management of Hypotension in Kidney Transplant Recipients (NCT04529005), a na phase 4 study. The primary outcome is Duration of ATII Vasopressor Usage in the Intraoperative Setting.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04529005 |
| Phase | Phase 4 |
| Condition | Shock, Surgical, Shock, Hypotension and Shock |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Illinois Chicago |
| Results posted | Yes |
2. Clinical Question
Population
Kidney transplant recipients who developed a need for vasopressors during or after surgery were the population of interest. The study description says recipients who gave informed consent would receive angiotensin II if vasopressor support became necessary. The registry record lists an enrollment of 20, but does not report how many recipients started angiotensin II intraoperatively, which is the population specified for the primary endpoint.
Intervention
The intervention was angiotensin II, identified in the record as Giapreza. The study description says it would be used as the first vasopressor when vasopressor support was needed in the intraoperative or postoperative setting. The registry record does not provide outcome data that would show the hemodynamic response or describe safety beyond the posted adverse-event counts.
Comparator
There was no concurrent comparator arm. The study is registered as a single-group study, with no allocation specified and no masking. It therefore does not directly compare angiotensin II with catecholamine vasopressors, usual care, or another treatment. Statements in the study description about existing practice or earlier research do not constitute a control group within this trial.
Primary question
The stated primary objective was to evaluate safety and hemodynamic effects of angiotensin II in the renal transplant population. The primary endpoint focuses more narrowly on the duration of angiotensin II vasopressor use in the operating room, reported as a median with an inter-quartile range among those who started it intraoperatively. The endpoint result is not reported in the registry record.
In statistical terms, this study is intended to describe what happened after angiotensin II was used in a particular perioperative setting. It can report the duration of use and record safety outcomes, but the single-group design cannot separate treatment effects from the natural course of hypotension, other care, or patient characteristics. The clinical question is therefore descriptive and exploratory rather than a randomized estimate of comparative benefit or harm.
3. Trial Design
The registry record describes a completed Phase 4 study sponsored by University of Illinois Chicago. The study began on 2020-08-13, reached primary completion on 2021-08-01, and has a completed status. Enrollment is listed as 20. The record classifies the study model as single-group, with allocation listed as not applicable and masking listed as none.
The intervention was angiotensin II (Giapreza). According to the study description, consenting kidney transplant recipients would receive it as their first vasopressor if vasopressor support became necessary during or after the transplant operation. Because there is no concurrent control arm, the design does not support a direct treatment comparison. The stated objective is to evaluate safety and hemodynamic effects in the renal transplant population.
The primary outcome concerns the duration of angiotensin II use in the operating room. Its stated population is participants who started angiotensin II intraoperatively, and the planned summary is a median and inter-quartile range in hours. The record also lists safety outcomes involving arrhythmias, peripheral or visceral ischemia, thrombosis, fungal infections, hyperglycemia, and delayed graft function.
The registry record does not report a statistical analysis plan, an explanation of sample-size justification, or any analysis results. It lists no analyses. The record also does not report how many enrolled recipients started the drug intraoperatively or whether every listed outcome was assessed for every recipient. These omissions limit what can be concluded about the study’s implementation and the precision of its outcome estimates.
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 | Angiotensin II (Giapreza) |
|---|---|
| STARTED | 20 |
| COMPLETED | 20 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Started ATII intraoperatively
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 | Angiotensin II (Giapreza) |
|---|---|---|
| Participants analysed | 20 | |
| Age, Continuous | years | 56.3 (SD 10.7) |
| Sex: Female, Male: Female | Participants | 9 |
| Sex: Female, Male: Male | Participants | 11 |
| Race/Ethnicity, Customized: White | Participants | 6 |
| Race/Ethnicity, Customized: Black | Participants | 7 |
| Race/Ethnicity, Customized: Hispanic | Participants | 5 |
| Race/Ethnicity, Customized: Other | Participants | 2 |
| Region of Enrollment: United States | Participants | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Duration of ATII Vasopressor Usage in the Intraoperative Setting, measured over Duration of usage during the transplant surgery - presented in hours.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | hours |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the duration of angiotensin II vasopressor use in the intraoperative setting, measured in hours. It is defined for the population that started angiotensin II intraoperatively, rather than for all enrolled recipients. The registry specifies a median and inter-quartile range as the summary measures. The endpoint value and its inter-quartile range are not reported in the registry record.
Duration is a measure of treatment exposure in this setting. It can describe how long the vasopressor was used during transplant surgery, but it is not itself a direct measure of blood pressure response, organ function, or a comparison with another treatment. A shorter or longer duration cannot be interpreted on its own as evidence of better or worse outcomes, particularly without the clinical context and other outcome data.
General statistical explanation: the median represents the middle of an ordered set of observations and is less sensitive to unusually long or short values than the arithmetic mean. The inter-quartile range describes the spread of the central portion of the observations. Together, these summaries can be useful when durations are unevenly distributed or have extreme values. However, they do not show the full distribution, and they do not indicate how precisely the study estimates a treatment effect. No confidence interval or other uncertainty measure for this endpoint is reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted registry information establishes the study’s purpose and design but does not provide the primary endpoint result. Although the endpoint is defined as intraoperative angiotensin II use duration summarized by a median and inter-quartile range, neither the median nor the inter-quartile range is reported in the registry record. The record therefore does not permit a numerical description of observed use duration or its variability.
The study is single-group and has no concurrent comparator. Any observed outcome in this design would describe what occurred among recipients receiving angiotensin II, but would not by itself establish what would have occurred under another vasopressor strategy or without angiotensin II. Differences in patient condition, clinical decisions, and other care could influence outcomes. The registry record does not report an analysis that adjusts for such factors.
For safety, the record lists 0 serious adverse events among 20 at risk, 1 other adverse event among 20 at risk, and 0 deaths. It does not list top serious adverse-event terms. The identity and clinical details of the other adverse event are not reported in the registry record. These counts are limited observations from this study; they do not establish that an event cannot occur, and they do not determine whether an event was caused by angiotensin II. Percentage values for these counts are not reported in the registry record.
The registry lists secondary safety outcomes concerning arrhythmias, peripheral or visceral ischemia, thrombosis, fungal infections, hyperglycemia, and delayed graft function. Outcome results for these measures are not reported in the registry record. Their inclusion as planned outcomes should not be mistaken for evidence that events were observed or absent.
The record lists no statistical analyses. It does not report estimates of effect, confidence intervals, hypothesis tests, or a statistical plan. As a result, there is no basis in the record for judging statistical precision or testing a treatment-related hypothesis. The enrollment figure alone cannot answer those questions. It is also not possible to assess whether missing observations, differing follow-up, or outcome ascertainment affected the reported counts.
Overall, the registry supports a description of the study as a small, completed, single-group evaluation with a defined intraoperative duration endpoint and recorded adverse-event counts. It does not provide the outcome information needed to characterize the primary endpoint or most listed secondary outcomes. The absence of a comparator and inferential results means the record cannot establish comparative effectiveness or causal safety conclusions.
9. Statistical Methods Explained
The registry identifies a median and inter-quartile range for the primary endpoint. It does not report a statistical analysis plan or a statistical analysis for any outcome. The following concepts explain how the specified summaries and the design relate to interpretation; they are general statistical explanations, not a claim about methods used by the investigators.
Why report a median and inter-quartile range?
A median describes the central observation after values are ordered. Unlike a mean, it is not pulled as strongly by an unusually long duration. The inter-quartile range describes the spread of the central half of the observations, with the lower and upper quartiles marking the boundaries of that range. These summaries can be appropriate for duration data when the distribution is skewed or includes extreme values.
These summaries still have limitations. They do not show every observation, reveal the shape of the distribution, or indicate the precision of the median. A confidence interval could express uncertainty in an estimated median, but no confidence interval for the primary endpoint is reported in the registry record. Since the endpoint result itself is also not reported, the planned summary cannot be evaluated from the record.
What does the single-group design permit?
A single-group study can describe outcomes among participants who receive the intervention. It can provide information about treatment exposure and recorded events in the study setting. Without a concurrent comparator, however, it cannot distinguish the outcome under angiotensin II from the outcome that would have occurred under another management strategy. The absence of random allocation also means that the study does not create randomized groups whose baseline characteristics can be compared.
General statistical explanation: randomization helps balance measured and unmeasured prognostic factors on average between treatment groups. In a single-group study, that balancing function is absent. A before-and-after comparison, if one were reported, would also need to account for changes over time and other simultaneous care. No such comparison or adjustment is reported in the registry record.
How should adverse-event counts be understood?
Counts describe how many events or affected participants were recorded under the registry’s categories. They are not, by themselves, estimates of comparative risk. A count of 0 serious adverse events in this study does not prove that serious events are impossible, and it cannot show whether the intervention changed their occurrence. Similarly, a count in the other adverse-event category does not identify its type or establish causation. The registry’s group figures list 20 at risk for serious and other events, with 0 serious events, 1 other event, and 0 deaths. The record does not report more detailed definitions, event narratives, or outcome-specific percentages.
General statistical explanation: uncertainty around event rates can be substantial when the number of observed events is small. Confidence intervals can convey this uncertainty, while comparative analyses require a suitable comparator and an explicit method. Neither an inferential safety analysis nor confidence intervals are reported in the registry record. It is therefore more accurate to describe the posted counts than to infer a rate difference or treatment effect.
What can be said about the planning assumptions?
The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also distinguishes planning for participants per arm from total event counts for time-to-event outcomes. These are stated assumptions for illustrations, not evidence that the study itself was designed as a two-arm trial. The registered study is single-group, and the record does not report a design justification or any observed effect value on which to base an interpretation.
General statistical explanation: a sample-size calculation depends on assumptions about the effect to detect, outcome variability or event frequency, significance level, allocation, and analysis method. Changing those assumptions changes the resulting planning estimate. Such calculations are prospective illustrations and do not measure the probability that a completed study has found a real effect. The record does not report an inferential analysis or an observed primary endpoint estimate, so no observed power conclusion is warranted.
Why does the lack of analysis detail matter?
The registry lists no analyses and does not describe how incomplete outcomes, repeated measurements, protocol deviations, or analysis populations were handled. Those choices can affect estimates and their interpretation. The primary endpoint is restricted to recipients who started angiotensin II intraoperatively, but the number in that endpoint population is not reported in the registry record. The record also does not report whether secondary outcomes were assessed for the same population or under another definition.
General statistical explanation: a prespecified analysis plan helps clarify which outcomes and populations are primary, how missing data are addressed, and how uncertainty is quantified. Without that information, readers cannot assess whether analytic decisions were made before results were known or determine the sensitivity of conclusions to alternative choices. In this record, the more fundamental limitation is that primary and secondary outcome results are largely not reported, so no analysis method can be evaluated against the observed data.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary duration outcome and secondary outcomes concerning arrhythmias, peripheral or visceral ischemia, thrombosis, fungal infections, hyperglycemia, and delayed graft function. It records 7 outcome measures, but lists no analyses. Results for the secondary outcomes are not reported in the registry record.
Multiplicity arises when several outcomes or statistical tests are considered. If each is tested separately, the chance of at least one apparently unusual result can increase, depending on the testing strategy. General statistical approaches include prespecifying a primary outcome, adjusting for multiple comparisons, or treating secondary findings as exploratory. The registry record does not report a multiplicity strategy, so it is not possible to assess how multiple outcomes were handled or whether any inferential results would account for them.
The record does not report missing-data methods, outcome-specific denominators beyond the adverse-event figures, or analysis populations beyond the stated primary-endpoint population of recipients who started angiotensin II intraoperatively. It does not report how many recipients belonged to that population or whether all planned outcome measurements were complete. These details matter because incomplete or differently assessed outcomes can affect both estimates and their interpretation.
Without reported analyses and outcome results, readers cannot determine whether missingness was present, how it was handled, or whether it could have influenced conclusions. These matters are not reported in 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 |
|---|---|---|---|
| Angiotensin II (Giapreza) | 0 | 20 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Angiotensin II (Giapreza) | 0 of 20 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 4% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Angiotensin II (Giapreza) | 1 of 20 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Angiotensin II (Giapreza) |
|---|---|---|
| Thrombocytopenia | Blood and lymphatic system disorders | 1 of 20 |
The adverse-event record lists 20 at risk for serious events, with 0 serious events reported and 0 deaths. It separately lists 20 at risk for other adverse events and 1 affected. The identity, severity details, timing, and outcome of that other adverse event are not reported in the registry record. The record lists no top serious adverse-event terms.
These are counts, not a comparative safety analysis. Because the study has a single group, the counts cannot show whether event occurrence differs from another treatment or from usual care. A count of 0 serious events does not establish that serious events cannot occur, especially beyond the observation captured in this study. The registry does not report percentage values, confidence intervals, or a causal assessment of the event.
The listed secondary safety outcomes include arrhythmias, peripheral or visceral ischemia, thrombosis, fungal infections, hyperglycemia, and delayed graft function, but their results are not reported in the registry record. Their presence on the outcome list does not show that any particular event occurred or did not occur. The posted adverse-event counts should therefore be read narrowly, as recorded counts in this single-group study.
12. What the Result Does, and Does Not, Mean
The record describes a completed single-group study of angiotensin II use in kidney transplant recipients with perioperative hypotension. It specifies an intraoperative duration endpoint and lists several safety outcomes. The posted safety counts are 0 serious adverse events among 20 at risk, 1 other adverse event among 20 at risk, and 0 deaths. These observations describe the registry’s reported event categories, not a comparison with another treatment.
The primary endpoint result is not reported in the registry record. Nor are results reported for the listed secondary outcomes. Consequently, the record does not allow readers to determine the observed duration of intraoperative use, the spread of those durations, or the frequency of the specified secondary outcomes. It also does not give confidence intervals or statistical tests that would quantify uncertainty in outcome estimates.
The results do not establish that angiotensin II is more effective, less effective, safer, or less safe than another vasopressor strategy. There is no concurrent comparator and no reported causal analysis. The counts also cannot establish that a reported event was caused by the intervention. These limits apply even though the record identifies a completed study and a defined enrollment.
General statistical explanation: descriptive observations can help characterize what was recorded in a study, while comparative conclusions require a design and analysis that support comparison. Precision is also important: an estimate without an uncertainty measure may be compatible with a wide range of underlying values. Here, the primary estimate and its uncertainty are not reported. The most defensible interpretation is therefore limited to the design, endpoint definition, and adverse-event counts stated in the registry record.
13. Why This Trial Matters Statistically
This study is statistically notable because its clinical question concerns vasopressor use in a focused perioperative setting, while its registered design is single-group. That design can describe use and observed events, but it does not provide a concurrent counterfactual for estimating what would have happened under another vasopressor approach. Recognizing this distinction is central to interpreting a pilot evaluation without turning descriptive observations into comparative claims.
The primary endpoint is duration of intraoperative use, summarized using a median and inter-quartile range. This choice focuses on treatment exposure and can be informative when durations are not symmetrically distributed. Yet the registry record does not report the summary values. The endpoint definition alone cannot show the typical duration or its variability.
The safety information also illustrates why event counts need context. The registry reports no serious adverse events and no deaths in the listed group, alongside one other adverse event. These are useful descriptive details, but the record does not provide event details, uncertainty intervals, or comparative estimates. The listed secondary outcomes have no reported results.
More broadly, the record shows why registration fields and outcome reporting serve different purposes. A specified endpoint and completed status document the intended study and its administrative progress; they do not substitute for analysis results. The absence of a reported analysis plan also leaves methods for missing data, multiplicity, and analysis populations unclear. Statistically, the study’s value as a descriptive investigation should be distinguished from evidence that could support a comparative treatment conclusion.
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 primary limitation for interpreting outcomes is that the registry record does not report the primary endpoint result. The median and inter-quartile range for intraoperative duration are absent, as are results for the listed secondary outcomes. This prevents assessment of the observed hemodynamic-use pattern and the recorded frequency of those outcomes.
The design is single-group, with no comparator, no allocation, and no masking. Outcomes therefore cannot be interpreted as comparative treatment effects. The study description identifies the primary endpoint population as recipients who started angiotensin II intraoperatively, but the size of that population is not reported in the registry record. The record does not explain how outcome availability or missing data were handled.
The safety information is limited to counts. The nature of the one other adverse event is not reported, no serious-event terms are listed, and no percentage values or uncertainty estimates are reported. The record does not describe event ascertainment or provide enough detail to evaluate causal attribution.
Finally, the registry lists no analyses and does not report a statistical analysis plan, multiplicity approach, or sample-size justification. The study’s enrollment figure cannot replace those details or establish the precision of an unreported endpoint estimate. Together, these limitations make the record informative about the registered design and selected event counts, but insufficient for a complete statistical assessment of outcomes.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Angiotensin II in the Perioperative Management of Hypotension in Kidney Transplant Recipients — NCT04529005.
- Registry record last updated 2022-12-21; status last verified 2022-11.
- Results first posted 2022-12-21.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT04529005 is a completed Phase 4, single-group study sponsored by University of Illinois Chicago. The record lists enrollment of 20, no allocation, and no masking. Angiotensin II (Giapreza) was the intervention. The study description concerns use as a first vasopressor when support was needed during or after kidney transplant surgery.
The primary endpoint is intraoperative duration of angiotensin II use, summarized as a median and inter-quartile range among recipients who started treatment intraoperatively. Its result is not reported in the registry record. Listed secondary outcomes concern adverse events and delayed graft function, but their results are not reported. The record lists 0 serious adverse events, 1 other adverse event, and 0 deaths, and lists no analyses. The single-group design does not provide a direct comparison with another treatment.