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 Pilot Study of the Treatment of Vascular Endothelial Growth Factor(VEGF)Signaling Pathway Inhibitor-Induced Hypertension (NCT00607477), a non-randomized na study. The primary outcome is Magnitude of Change in Blood Pressure.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00607477 |
| Phase | NA |
| Condition | Treatment Induced Hypertension |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 2 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Chicago |
| Results posted | Yes |
2. Clinical Question
The study was intended to describe the length of time and extent of blood-pressure response to minoxidil and hydralazine among cancer patients with difficult-to-treat hypertension induced by VEGF inhibitors. Its registered primary outcome was the magnitude of change in blood pressure over 21 days. The record does not give a numerical blood-pressure result, and it states that no participants were analyzed because accrual was poor and the number of participants was insufficient.
Population
Cancer patients with difficult-to-treat VEGF-inhibitor treatment-induced hypertension were the intended population. The registry reports total enrollment of 2, but says no participants were analyzed for the primary outcome.
Intervention
One study arm was assigned to minoxidil, a direct vasodilator. The registry does not report dose or administration details.
Comparator
The other arm was assigned to hydralazine, also described as a direct vasodilator. The study was nonrandomized, so the arms were not established as like-for-like comparison groups.
Primary question
The intended question concerned the magnitude and duration of blood-pressure response to these drugs. The registered primary measure addresses magnitude over 21 days; no analyzed outcome result is reported.
The registry does not establish that the study could compare the drugs reliably. With no analyzed participants and no numerical endpoint result, the central clinical question remains unanswered by the posted results. The record is best read as documentation of the study’s purpose and early termination, rather than as evidence about comparative response.
3. Trial Design
This was a pilot study listed as phase NA, with nonrandomized allocation, no masking, and a parallel model. The two named arms were minoxidil and hydralazine. In a parallel design, different participants are assigned to separate arms rather than each participant receiving both interventions in sequence; however, the registry does not describe the assignment procedure beyond identifying allocation as nonrandomized.
The study was sponsored by the University of Chicago. The registry lists a start date of 2008-01 and a primary completion date of 2009-01, and records the study status as terminated. Total enrollment is listed as 2. The primary outcome description states that no participants were analyzed because of poor accrual and insufficient numbers of participants.
Nonrandomized allocation means the registry does not document random assignment as a way to balance participant characteristics across arms. Any observed difference between groups, if one had been reported, could therefore reflect differences between the participants as well as differences associated with treatment. In this record, there is no analyzed primary outcome with which to make even a descriptive arm comparison.
The two treatment arms do not constitute a placebo or untreated control group. Both are active drugs named in the study description, and the record does not identify a control arm. No masking was recorded, so the trial is listed as unmasked; details about who knew treatment assignment are not reported in the registry record.
The registry does not report a planned sample-size justification, detailed eligibility criteria, drug doses, treatment assignment process, or statistical analysis plan. It also does not describe interim analyses. These omissions limit reconstruction of the intended conduct, but they do not change the key reported outcome: no participants were analyzed for the primary blood-pressure measure.
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 | Hydralazine | Minoxidil |
|---|---|---|
| STARTED | 0 | 2 |
| COMPLETED | 0 | 2 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: No participants analyzed due to poor accrual and insufficient numbers of participants.
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 | Hydralazine | Minoxidil | Total |
|---|---|---|---|---|
| Participants analysed | 0 | 2 | 2 | |
| Age, Categorical: <=18 years | participants | — | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | participants | — | 1 | 1 |
| Age, Categorical: >=65 years | participants | — | 1 | 1 |
| Gender: Female | participants | — | 1 | 1 |
| Gender: Male | participants | — | 1 | 1 |
| Region of Enrollment: United States | participants | — | 2 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Magnitude of Change in Blood Pressure, measured over 21 days.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The registered primary endpoint is titled “Magnitude of Change in Blood Pressure,” with a timeframe of 21 days. Blood pressure is the measurement targeted by the study’s stated purpose: describing both the extent and duration of response to minoxidil and hydralazine in patients with VEGF-inhibitor treatment-induced hypertension. The registry’s primary endpoint title addresses magnitude; the record does not specify a separate numerical endpoint for duration.
The registry does not report the endpoint’s unit, statistical parameter, or dispersion measure. It also contains no numerical estimate or analysis for this outcome. Its population description says that no participants were analyzed because of poor accrual and insufficient numbers of participants.
In general, a prespecified primary endpoint gives a study a focal outcome for assessing its stated research question. A clearly defined measurement and timeframe help readers understand what was to be measured and when. Here, the timeframe is reported, but details needed to interpret a change score—such as the unit, the precise parameter, and how variability would be summarized—are not reported in the registry record. Because the endpoint has no analyzed observations, it cannot quantify blood-pressure change or support a comparison between the two arms.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The most important result for interpretation is the absence of an analyzed primary outcome. The registry says that no participants were analyzed for the magnitude-of-change-in-blood-pressure endpoint because accrual was poor and the number of participants was insufficient. Consequently, there is no posted estimate of blood-pressure change, no measure of uncertainty around an estimate, and no result describing how long a response lasted.
Total enrollment is listed as 2, but this does not supply an analyzed outcome. Enrollment and analysis are distinct: a person may be enrolled without contributing to a particular endpoint analysis, and the record specifically says that no participants were analyzed for the primary measure. The available record does not explain participant flow in enough detail to determine further reasons or the distribution of enrollment between treatment arms.
The design also constrains what a treatment comparison could establish. Allocation was nonrandomized, and the arms were not a like-for-like control comparison. Even if numerical results had been posted, differences between the groups would need cautious interpretation because assignment was not random. In the actual record, the absence of primary outcome analyses means that there is no observed arm contrast to interpret in the first place.
The safety listings should also be read descriptively and in light of the small enrollment. For minoxidil, the registry records 2 participants at risk for serious adverse events and 0 affected; for hydralazine, it records 0 at risk and 0 affected. The record lists 2 participants at risk for other adverse events in the minoxidil group and 1 affected. It lists 0 at risk and 0 affected for other adverse events in the hydralazine group. These counts do not provide a basis for a reliable comparison between treatments, especially because the hydralazine group has no participants listed at risk. Death counts are not reported in the registry record.
The study status is terminated, and the registry attributes the absence of primary analyses to poor accrual and insufficient participant numbers. This explains why the intended question did not receive an outcome estimate in the posted results; it does not establish the direction or size of any blood-pressure response. No conclusion that either drug performed better, worse, or similarly is supported by these data.
9. Statistical Methods Explained
The registry identifies a primary endpoint but does not report a statistical analysis for it. The distinctions below explain how common statistical ideas relate to the record; they do not describe methods that the investigators are known to have used.
What an endpoint estimate would represent
In general, an endpoint estimate condenses observed measurements into a quantity that addresses the research question. For a change in blood pressure, the estimate would depend on the specific definition of change, the measurement unit, and the summary parameter chosen. The registry gives the endpoint title and a 21-day timeframe, but the unit, parameter, and dispersion measure are not reported. Without analyzed observations or a stated summary, there is no estimate to interpret.
A descriptive estimate and an inferential comparison are not the same thing. A description might characterize the observed change within an arm. A comparison would quantify how outcomes differed between arms and would require a defined contrast and an analysis approach. Neither kind of primary outcome result is reported for this study. The registry lists no analyses.
Why precision matters
In general, a confidence interval expresses the uncertainty around an estimate under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, while an interval that includes a range of plausible values should not be treated as a single known effect. No confidence interval is reported for the primary endpoint because no participants were analyzed for it. The reader therefore cannot assess precision, plausible response size, or whether an estimate would be compatible with different interpretations.
A small number of observations generally gives limited information about variability and can make estimates unstable. This is a general statistical point, not a calculated finding about the study. Here, the registry reports total enrollment of 2 and no analyzed participants for the primary endpoint. There is thus no observed endpoint sample from which to estimate response variability or uncertainty.
Nonrandomized allocation and comparison
In general, random assignment helps make treatment groups comparable in expectation with respect to both measured and unmeasured characteristics. Nonrandomized allocation does not provide that safeguard. Baseline differences or the process used to assign treatment may influence outcomes, so a between-arm difference can be difficult to attribute to treatment alone. The record identifies the allocation as nonrandomized and explicitly does not establish a like-for-like control comparison.
That design limitation is separate from the lack of outcome analysis. A nonrandomized study can still report descriptive observations, but this record reports no analyzed primary endpoint. It is therefore not possible to describe an arm-specific blood-pressure estimate or to evaluate a between-arm difference from the posted results.
Over-dispersion and count outcomes
In general, over-dispersion occurs when count data vary more than a chosen statistical model expects. A model that does not account for such extra variability can give uncertainty estimates that are too small. That concept may be relevant in some studies of repeated events or count outcomes, but the registry does not report a count-based primary endpoint, a model, or an over-dispersion assessment for this trial. It should not be inferred that such a method was used.
Sample-size planning versus observed evidence
In general, sample-size planning specifies assumptions about a target effect, variability, allocation, and a desired operating characteristic before a study begins. A planning illustration based on an observed effect is a separate hypothetical calculation; it is not evidence that a study was designed to achieve a particular power, and it is not observed power. The registry does not report the trial’s own sample-size justification or the assumptions used to plan enrollment. Because the primary endpoint has no analyzed observations, the record also cannot provide an observed treatment effect for interpreting planning scenarios.
These distinctions matter because sample size does not repair an absent outcome analysis. An enrollment count alone cannot yield an effect estimate, precision interval, or valid comparison. The reported termination and lack of primary analysis should remain central when interpreting any statistical material associated with the study.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises in general when a study tests or estimates several outcomes, timepoints, treatment contrasts, or subgroups. If many statistical tests are interpreted together, the chance of apparently noteworthy findings can increase unless the analysis plan addresses the issue. The registry lists one outcome measure and no analyses. It does not report a multiplicity adjustment or a broader testing strategy, so it is not possible to determine whether multiplicity procedures were planned or needed for analyses beyond the listed endpoint.
The registry’s primary endpoint has a 21-day timeframe, but it does not report repeated measurement details or whether additional timepoints were planned. Although the study purpose mentions the length of time and extent of blood-pressure response, the record does not give a separate analyzed duration outcome. The relationship between that broader aim and any planned secondary outcomes is not reported in the registry record.
Missing-data handling cannot be evaluated from the posted results. The record says no participants were analyzed for the primary endpoint because of poor accrual and insufficient numbers of participants. It does not report a participant-level accounting of missing measurements, reasons for missingness beyond the stated accrual problem, or any imputation or sensitivity analysis. No analysis population is described, and the registry lists no analyses.
In general, an analysis population defines which participants contribute to a particular result. Different populations can answer different questions, so a report should make inclusion rules clear. Here, the absence of analyzed participants for the primary outcome means there is no reported population definition to assess. Enrollment of 2 should not be mistaken for an analyzed population of the same size.
The registry does not report a prespecified statistical plan, interim analysis procedures, or a method for handling multiplicity or missing outcome data. Those details should not be inferred from the endpoint listing or the safety counts.
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 |
|---|---|---|---|
| Minoxidil | 0 | 2 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Hydralazine | 0 of 0 |
| Minoxidil | 1 of 2 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Hydralazine | Minoxidil |
|---|---|---|---|
| diarrhea (grade 1) | Gastrointestinal disorders | 0 of 0 | 1 of 2 |
The safety record lists serious adverse events separately from other adverse events. In the minoxidil group, 2 participants are listed at risk for serious adverse events and 0 are listed as affected. In the hydralazine group, 0 are listed at risk and 0 are listed as affected. A group with no participants listed at risk does not provide an informative basis for judging the frequency of an event in that group.
For other adverse events, the minoxidil group lists 2 participants at risk and 1 affected. The hydralazine group lists 0 at risk and 0 affected. These are small descriptive counts, not a comparative safety analysis. They should not be converted into a conclusion about relative safety or treatment effects.
The registry does not list serious adverse-event terms. Death counts are not reported in the registry record. The safety figures should also be considered alongside the overall record: the study was terminated, enrollment was 2, and no participants were analyzed for the primary outcome. The posted safety counts cannot establish the full safety profile of either drug in the intended population.
12. What the Result Does, and Does Not, Mean
The record documents a pilot study intended to describe blood-pressure response to minoxidil and hydralazine in cancer patients with difficult-to-treat VEGF-inhibitor treatment-induced hypertension. It identifies the primary endpoint as magnitude of change in blood pressure over 21 days and records two parallel treatment arms. It also reports that the study was terminated and that no participants were analyzed for the primary outcome because accrual was poor and participant numbers were insufficient.
What the record does not show is a numerical response to either drug. It contains no primary endpoint estimate, no uncertainty interval, and no analyzed comparison. It therefore cannot answer how large a blood-pressure change occurred, how long a response lasted, or whether outcomes differed between minoxidil and hydralazine.
The trial’s nonrandomized design would have limited the interpretation of a comparison even if results had been available. Treatment allocation was not randomized, and there was no like-for-like control comparison. The reported safety counts are likewise too limited to support a comparative conclusion, particularly because no participants are listed at risk in the hydralazine group.
In general, an inconclusive or unavailable estimate should not be treated as evidence of no effect. At the same time, the study’s stated purpose cannot be treated as evidence that either treatment produced a response. The appropriate reading is that the registry records an intended research question but does not contain analyzed outcome data capable of resolving it.
The findings also do not establish that the study was designed with a particular statistical power or that any planned analysis was completed. The sample-size justification and detailed statistical plan are not reported in the registry record. The terminated status and lack of primary analyses are the defining limits on what can be concluded from the posted results.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the difference between a research question, a registered endpoint, enrollment, and an analyzed result. The registry specifies an intended question about blood-pressure response and names a primary outcome with a timeframe. But the endpoint description also states that no participants were analyzed because of poor accrual and insufficient numbers. A clearly stated objective does not by itself produce evidence about the objective.
The record also highlights why enrollment should not be confused with analysis. Total enrollment is listed as 2, but no primary endpoint observations were analyzed. Without an analyzed outcome, there is no estimate to summarize and no precision to evaluate. Reporting the enrollment figure alone cannot substitute for the missing endpoint result.
Design features matter as well. The study was nonrandomized and unmasked, with separate minoxidil and hydralazine arms. A nonrandomized allocation does not ensure comparable groups, while the absence of a reported analysis means there is no arm comparison to scrutinize. The safety counts, too, need to be interpreted in context rather than treated as a comparative result.
Finally, this record shows the importance of distinguishing a terminated study from a study that reports a null finding. No analyzed primary outcome is not the same as an estimate near zero. The registry supports the conclusion that the intended question was not answered in the posted results, but it does not establish what the treatment response would have been.
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 most consequential limitation is that no participants were analyzed for the primary blood-pressure outcome. The registry attributes this to poor accrual and insufficient participant numbers. Although total enrollment is listed as 2, the record does not report participant flow or explain how enrollment was distributed between the arms for the primary outcome.
The endpoint description is incomplete for statistical interpretation. The timeframe is 21 days, but the unit, parameter, and dispersion measure are not reported. There is no numerical outcome estimate, uncertainty measure, or description of blood-pressure response over time. The stated study purpose includes the length of time and extent of response, but the record does not provide analyzed duration results.
The design was nonrandomized, unmasked, and lacked a like-for-like control comparison. The registry does not describe the allocation process, baseline characteristics, treatment doses, or detailed eligibility criteria. These details are not reported in the registry record and should not be inferred.
The safety counts are limited, with no participants listed at risk in the hydralazine group. The record does not list serious adverse-event terms, and death counts are not reported in the registry record. These data cannot characterize comparative safety.
Finally, a sample-size justification, detailed statistical analysis plan, interim analysis procedures, and missing-data methods are not reported. The status is terminated. Together, these limitations mean the registry record offers no analyzed primary result and only a narrow descriptive account of safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pilot Study of the Treatment of Vascular Endothelial Growth Factor(VEGF)Signaling Pathway Inhibitor-Induced Hypertension — NCT00607477.
- Registry record last updated 2014-06-10; status last verified 2014-06.
- Results first posted 2011-02-16.
- 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
NCT00607477 is a University of Chicago pilot study of minoxidil and hydralazine for VEGF-inhibitor treatment-induced hypertension. The registry lists a nonrandomized, unmasked, parallel design, phase NA, enrollment of 2, and terminated status. It records a start date of 2008-01 and a primary completion date of 2009-01.
The primary outcome was magnitude of change in blood pressure over 21 days. The registry states that no participants were analyzed because of poor accrual and insufficient numbers. No primary outcome estimate or analysis is reported. Safety listings include 0 serious adverse events among 2 participants at risk in the minoxidil group and no participants listed at risk in the hydralazine group. For other adverse events, 1 of 2 participants at risk was affected in the minoxidil group; none were listed at risk in the hydralazine group. Death counts are not reported in the registry record.