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 Mechanisms of Refractory Hypertension (Reserpine) (NCT03223272), a na phase 2 study. The primary outcome is Change Ambulatory Systolic Blood Pressure.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03223272 |
| Phase | Phase 2 |
| Condition | Refractory Hypertension |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 7 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Alabama at Birmingham |
| Results posted | Yes |
2. Clinical Question
Population
The registry describes people with refractory hypertension. The brief summary characterizes the participants as patients whose hypertension had not responded to other classes of antihypertensive agents. Further eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
The intervention was open-label reserpine, described as 0.1 mg daily for 4 weeks. The registry identifies reserpine as a drug intervention. It does not report additional details about treatment adherence or changes to treatment during follow-up.
Comparator
There was no separate comparator group. The study is recorded as single-group, with allocation listed as NA and masking listed as none. Baseline measurements provide a reference for the planned change outcome, but they are not a concurrent control group.
Primary question
The primary outcome was change in 24-hour ambulatory systolic blood pressure, measured in mmHg, with a stated timeframe of baseline and 8 weeks. The brief summary frames the investigation around whether heightened sympathetic tone may contribute to refractory hypertension, assessed by quantifying the blood-pressure response to reserpine. The registry record does not report the observed outcome values or an analysis answering that question.
3. Trial Design
This was a Phase 2, completed, single-group study sponsored by the University of Alabama at Birmingham. The registry lists enrollment of 7 participants and identifies refractory hypertension as the condition under study. The recorded start date is 2015-07-23, and the primary completion date is 2020-01-31.
All participants were assigned to the reserpine group; the registry describes open-label reserpine 0.1 mg daily for 4 weeks. There was no randomized allocation, and no separate control arm is listed. Masking is recorded as none. Consequently, the design does not support a like-for-like comparison between people receiving reserpine and people assigned to another treatment or to no treatment. A before-and-after change can describe measurements in the treated group, but by itself it cannot separate treatment-associated change from other influences over time.
The primary outcome is described as change in 24-hour ambulatory systolic blood pressure, with measurements at baseline and 8 weeks. The treatment description specifies 4 weeks, while the primary outcome timeframe names baseline and 8 weeks. The registry record does not explain this timing, so no further interpretation of the schedule is warranted.
The registry lists one primary outcome measure and no analyses. The detailed statistical analysis plan, any sample-size justification, and any interim analyses are not reported in the registry record. The recorded completion status indicates that the study is completed, but does not establish that outcome results were entered into the registry.
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 | Reserpine |
|---|---|
| STARTED | 7 |
| COMPLETED | 6 |
| NOT COMPLETED | 1 |
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 | Reserpine |
|---|---|---|
| Participants analysed | 7 | |
| Age, Continuous | years | 49.5 (SD 9.4) |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 2 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| 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 | 7 |
| Race (NIH/OMB): White | Participants | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 7 |
6. Primary Endpoint
The registry lists the primary outcome as Change Ambulatory Systolic Blood Pressure, measured over Baseline and 8 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mmHg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in 24-hour ambulatory systolic blood pressure, measured in mmHg. Systolic pressure is the higher pressure recorded during a heartbeat; ambulatory measurement refers to monitoring across a 24-hour period rather than relying on a single clinic reading. Repeated measurement across ordinary daily activity can characterize blood pressure over a broader interval. That is the general rationale for ambulatory monitoring, not a claim about the specific monitoring procedures used in this study beyond the registry description.
A change endpoint compares a participant’s follow-up measurement with a baseline measurement. In a single-group study, the resulting change describes how the measured outcome varied over time among participants receiving the intervention. Without a concurrent control group, that change does not by itself identify what would have happened over the same period without reserpine.
The registry specifies the outcome as a mean with standard deviation and gives the timeframe as baseline and 8 weeks. It does not report the mean change, the standard deviation, participant-level measurements, or an estimate of uncertainty for the change. Therefore, the magnitude and precision of the primary outcome cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record establishes the study’s question and design, but it does not provide the primary outcome results. Although the primary measure is identified as change in 24-hour ambulatory systolic blood pressure, the registry record does not report a mean change, standard deviation, confidence interval, or statistical test. There is therefore no posted estimate from which to describe the direction, size, or precision of the blood-pressure change.
The study enrolled 7 participants in a single group receiving open-label reserpine. This design can describe measurements over time in that group if the measurements are available, but the registry record does not provide those measurements or analyses. Even when a before-and-after estimate is available, a single-group comparison does not provide the same evidence as a randomized comparison: without a concurrent control group, changes cannot be attributed solely to the intervention. Other explanations for change cannot be distinguished by the design alone.
The stated goal concerns whether refractory hypertension is attributable to heightened sympathetic tone, examined through the antihypertensive benefit of a sympatholytic agent. The registry description communicates that rationale; it is not evidence that the proposed mechanism was confirmed. The absence of posted primary outcome values means that the registry record does not allow assessment of whether blood pressure changed, or how uncertain any estimate might be.
Enrollment of 7 also means that estimates, if reported, would need to be interpreted in light of the small number of participants. In general, smaller studies often yield less precise estimates, though precision depends on the observed variability and analysis. Those outcome-specific quantities are not reported in the registry record, so the precision cannot be quantified for this study.
The record lists one serious adverse event among 7 participants at risk, with NSTEMI listed as a serious event term at 14.3%. It lists no other adverse events in the other-event category and no deaths. These are descriptive safety counts, not evidence that an event was or was not caused by reserpine. The single-group design and small enrollment limit what can be inferred about comparative safety.
Overall, the registry record documents a completed Phase 2 investigation and its intended endpoint, but does not report results sufficient to determine the observed blood-pressure response or its statistical uncertainty. No treatment-effect conclusion follows from the design description alone.
9. Statistical Methods Explained
The primary measure is continuous: it is a blood pressure value expressed in mmHg, and the registry specifies a mean and standard deviation. In general, a mean describes the average measurement in a group, while a standard deviation describes how dispersed individual measurements are around that average. Neither quantity, nor a mean change calculated from them, is reported in the registry record.
What does a change estimate represent?
A change estimate compares the follow-up value with the baseline value. It can be summarized as an average change across participants, but the interpretation depends on which participants have measurements at each time and how the analysis handles missing observations. Those analysis details are not reported in the registry record. The endpoint description gives baseline and 8 weeks as the timeframe, but does not provide the observed values or explain how measurements at those times were combined.
A confidence interval is a range of values compatible with the data under a specified statistical model and procedure. In general, a narrower interval indicates greater precision, while a wider interval indicates less precision. The registry record does not report a confidence interval or the information needed to evaluate one. A p-value, if reported, would address compatibility with a specified null hypothesis under the analysis assumptions; it would not itself express the size or clinical importance of an effect. No p-value or inferential analysis is reported in the registry record.
Why does the design matter?
This is a single-group study with no randomized control group. A baseline measurement is useful as a reference, but it does not serve as a concurrent control. General influences on measurements over time, including changes unrelated to the intervention, cannot be separated from intervention-associated change using a single-group before-and-after comparison alone. Open-label treatment also means masking is not part of the recorded design. The registry lists masking as none; other procedures intended to reduce measurement or assessment bias are not reported in the registry record.
Random allocation is not listed, and allocation is recorded as NA. The record explicitly identifies this as not a randomized comparison, with no like-for-like control comparison. Accordingly, the central statistical interpretation should remain descriptive unless a more detailed analysis and appropriate supporting information are reported elsewhere. Such information is not reported in the registry record.
How should planning illustrations be read?
The planning illustrations are described as calculations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They are planning illustrations, not observed power and not the design of this single-group trial. For non-time-to-event outcomes, their stated unit is participants per arm; time-to-event illustrations use total events. The registry record does not report the observed primary outcome effect, so its magnitude and the basis for the illustrations cannot be independently assessed from the record.
In general, a planning calculation asks how many participants might be required under specified assumptions to detect a chosen effect. Such a calculation is conditional on its assumptions and does not establish that a study has a particular probability of finding a result after data have been collected. It should not be confused with the actual enrollment, which was 7, or with evidence about the outcome. The registry describes the illustrations as using fractions of the observed effect, but no numerical values for the illustrations or the effect are reported in the registry record.
What cannot be checked from the record?
The registry lists one outcome measure and no analyses. The model used for the primary endpoint, any adjustment for baseline values, the handling of repeated or missing measurements, and the analysis population are not reported in the registry record. Nor are the distribution of measurements, the observed variability, or any diagnostic checks reported. These omissions prevent a reader from checking whether a particular model’s assumptions were considered or whether the reported estimate, if any, would be robust to alternative methods.
For continuous outcomes, distributional assumptions matter because they influence how estimates and uncertainty are calculated. In general, unusually dispersed data or observations that differ markedly from the rest can affect means and standard errors. Over-dispersion is a concern in count data when observed variability exceeds what a chosen count model expects; it is not a basis for making claims about this continuous endpoint without relevant data. The registry record does not report information permitting assessment of the outcome distribution or model fit.
10. Confidence Intervals for Each Arm
No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Reserpine | 6 | -29.300 | 22.200 | -52.597 to -6.003 |
R code and output
arm <- c("Reserpine")
n <- c(6)
m <- c(-29.3)
sp <- c(22.2)
sd <- sp # posted standard deviations
for (i in seq_along(n)) {
se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}
CARM Reserpine 6 -29.300 22.200 -52.597 -6.00311. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure and no analyses. It does not report a statistical analysis plan, the tests performed, or whether any additional outcomes or subgroup analyses were examined. The approach to multiplicity is therefore not reported in the registry record. In general, testing multiple outcomes or hypotheses can increase the chance of obtaining at least one apparently notable result by chance; methods to address this depend on the analysis plan and the questions being tested. The record does not provide enough detail to determine whether such adjustments were relevant or used.
Missing-data methods are also not reported in the registry record. The entry does not state how many participants contributed baseline or 8-week measurements, whether any measurements were missing, or how missing observations were handled. These details matter because an analysis based only on participants with complete measurements can differ from one that uses other stated assumptions or methods. No particular missing-data procedure can be attributed to this study from the available registry information.
The analysis population is not reported in the registry record. It is not possible to determine whether the intended analysis included everyone enrolled, only participants who received treatment, or another defined group. The entry also does not report protocol deviations, treatment adherence, or exclusions from analysis. These omissions limit assessment of how closely any analysis population might correspond to the enrolled group.
Because no outcome analyses are listed, the record does not permit a review of multiplicity control, missing-data sensitivity analyses, or analysis-population choices. These are unknown rather than evidence that a particular method was or was not used outside the registry entry.
12. 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 |
|---|---|---|---|
| Reserpine | 1 | 7 | 14.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Reserpine | 0 of 7 |
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 |
|---|---|
| Reserpine | 0 of 7 |
Most frequent serious adverse event terms
| Event term | Organ system | Reserpine |
|---|---|---|
| NSTEMI | Cardiac disorders | 1 of 7 |
Serious events with the highest arm-level rate: nstemi (14.3%).
The registry lists 7 participants at risk for serious adverse events in the reserpine group and 1 participant affected. The serious event term listed is NSTEMI, with 14.3% recorded for that term. The record lists 7 participants at risk for other adverse events and 0 affected in that category. It lists 0 deaths.
These figures are descriptive counts from a group of 7 participants. A count of events or affected participants does not establish whether an event was caused by the intervention. The registry information presented does not report an assessment of causality or provide a comparator group for estimating a relative safety difference. The number at risk and the number affected should also be kept distinct: the former describes the group considered at risk, while the latter records the reported event count or affected participants.
The NSTEMI term and its recorded percentage describe the registry’s serious-event listing; they do not by themselves convey the full clinical course, timing, severity beyond the serious classification, or relationship to treatment. Further event details are not reported in the registry record. With a small single group and no control group, these counts should not be read as a comparative safety estimate.
13. What the Result Does, and Does Not, Mean
The registry record defines a focused research question: whether reserpine is associated with a change in 24-hour ambulatory systolic blood pressure among participants described as having refractory hypertension. It records an open-label, single-group intervention and a planned baseline-to-8-week outcome. These details explain what the study set out to measure, but they do not answer the question about the observed response.
The primary outcome values and statistical analyses are not reported in the registry record. As a result, the record does not show whether the measured blood pressure increased, decreased, or remained similar, and it provides no estimate of the magnitude or precision of a change. It also does not provide a basis for judging whether any observed change was compatible with random variation under a specified statistical model.
Even if a before-and-after change were available, the design would not isolate the effect of reserpine from other influences over time. There is no randomized control group, and masking is listed as none. The intended mechanistic interpretation about heightened sympathetic tone therefore cannot be established by the design description alone. No conclusion that the proposed mechanism was supported or refuted is warranted from the registry entry.
The enrollment of 7 further limits the scope of any generalization. A result in a small study group may be sensitive to the individual measurements, and the record does not report the participant characteristics needed to assess how closely this group represents other people with refractory hypertension. That does not invalidate the study’s question; it does mean that broader conclusions would require evidence beyond the design details recorded.
The safety listing provides a descriptive account of reported events, including 1 serious adverse event and no deaths. It cannot establish comparative risk or causality. The appropriate reading is therefore limited: the registry records a completed study and its intended endpoint, but not the outcome evidence needed to characterize efficacy, mechanism, or comparative safety.
14. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between a clearly stated research question and a result that can be evaluated from a registry entry. The record names a continuous primary outcome, its measurement unit, the summary measure, and a measurement timeframe. It also makes the single-group, open-label design apparent. Those features help readers understand what was intended, while the absence of outcome results and analyses places a firm boundary on interpretation.
The design matters because within-group change and treatment effect are not interchangeable. A baseline-to-follow-up comparison can describe change among participants, but a concurrent comparator is needed to distinguish that pattern from changes that might have occurred without the intervention. Randomization can support a more credible comparison by balancing influences across groups on average; no randomized comparison is recorded for this study. This is a general design principle, not a claim about unreported procedures.
The small enrollment also highlights the role of precision. In general, limited participant numbers can leave estimates uncertain, especially when outcome variability is substantial. Without the observed mean change, standard deviation, or confidence interval, the precision of this study’s primary endpoint cannot be assessed. A statistical planning illustration does not fill that gap and should not be mistaken for an observed result or observed power.
Finally, the safety counts illustrate the distinction between describing events and estimating comparative risk. A small single group can document reported events, but without a comparator and sufficient event information it cannot establish whether the intervention changed risk. The registry record therefore supports understanding of the study’s design and reporting gaps, rather than a conclusion about benefit, mechanism, or comparative safety.
15. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most direct limitation of the registry record is that it does not report the primary outcome results or any analyses. The planned measure is clear, but no mean change, standard deviation, confidence interval, or test result is available. This prevents evaluation of both the observed direction and the precision of the outcome.
The single-group design has no concurrent control group, and the study is recorded as open-label. A change from baseline, if available, would not by itself establish that reserpine caused the change. The lack of a like-for-like comparison also limits interpretation of safety counts as comparative evidence.
Enrollment was 7. The registry does not report participant characteristics, detailed eligibility criteria, adherence, withdrawals, or the number with outcome measurements at each timepoint. These omissions limit assessment of who was studied and whether the analyzed participants, if any, represent everyone enrolled.
The treatment description specifies daily reserpine for 4 weeks, while the primary outcome timeframe states baseline and 8 weeks. The reason for this timing is not reported in the registry record. The entry also does not report the measurement schedule in further detail or explain how the change outcome was calculated.
The statistical analysis plan, sample-size justification, missing-data methods, analysis population, multiplicity approach, and interim analyses are not reported in the registry record. The entry lists no analyses. These gaps prevent readers from evaluating model choices, exclusions, or the handling of uncertainty. The planning illustrations described in the record are not a substitute for observed results or a control group.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Mechanisms of Refractory Hypertension (Reserpine) — NCT03223272.
- Registry record last updated 2021-11-30; status last verified 2021-11.
- Results first posted 2021-11-30.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
NCT03223272 is recorded as a completed Phase 2, single-group study sponsored by the University of Alabama at Birmingham. It enrolled 7 participants with refractory hypertension and studied open-label reserpine 0.1 mg daily for 4 weeks. The primary outcome was change in 24-hour ambulatory systolic blood pressure, measured in mmHg, with a timeframe of baseline and 8 weeks.
There was no randomized comparator group, and masking was listed as none. The registry lists 1 serious adverse event among 7 participants at risk, identifies NSTEMI at 14.3%, reports 0 affected in the other-event category, and lists 0 deaths.
The primary outcome results, statistical analyses, and further details of the analysis plan are not reported in the registry record. The entry therefore describes the study question and design but does not provide evidence to estimate the blood-pressure change or its precision.