24-hour Blood Pressure Measurements and Ischemic Conditioning: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for 24-hour Blood Pressure Measurements and Ischemic Conditioning (NCT03303404), a na na study. The primary outcome is Change From Baseline in Flow Mediated Dilation After 24 Hour Ischemic Conditioning With Blood Pressure Cuff.

2. Clinical Question

In plain terms, the study was intended to examine whether endothelial function, assessed using flow-mediated dilation, differed after participants had undergone ambulatory blood pressure monitoring. The registry describes the before-and-after measurement plan, but it does not provide numerical baseline or post-monitoring values. Consequently, the direction and size of any observed change cannot be described from the registry record.

The single-group structure matters to the question. A baseline measurement can serve as a participant’s reference, but it does not provide the same information as a separate control group observed over the same period. Without a listed control group, the record cannot establish how measurements might have changed over that period in the absence of the monitoring procedure. The clinical question is therefore limited to the reported before-and-after assessment; the registry does not document a randomized comparison or a treatment-effect estimate.

3. Trial Design

The registry identifies this as a completed, single-group study of ambulatory 24-hour blood pressure monitoring. Enrollment is listed as 22. Allocation is recorded as NA, and masking is recorded as none. The intervention is a device named Ambulatory (24-hour) Blood Pressure. No separate comparator arm is described, and the arm description is blank.

The study start date is 2017-09-12, and the primary completion date is 2018-09-20. The status is COMPLETED. The phase is recorded as NA. These registry entries describe the administrative design and status; they do not establish what analyses were ultimately performed or whether all planned measurements were obtained.

The brief summary says the study was intended to determine whether 24-hour ambulatory blood pressure monitoring affects endothelial function, with flow-mediated dilation measured before and after the monitoring period. The primary outcome timeframe is listed as baseline and post 24 hour conditioning. The record therefore frames the endpoint as a change over time within the single group. It does not describe a randomized assignment, masking, or a like-for-like control comparison.

The registry lists one outcome measure and zero analyses. Numerical outcome results are not reported in the registry record. A protocol, detailed statistical analysis plan, sample-size justification, interim-analysis plan, and account of deviations from the planned design are not reported in the registry record. The planning assumptions attached to sample-size illustrations describe equal allocation between two arms, while the registered study model is single group. Those assumptions should not be read as a description of the actual study allocation or as evidence that the study had a two-arm design.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Flow Mediated Dilation After 24 Hour Ischemic Conditioning With Blood Pressure Cuff, measured over Baseline, Post 24 hour conditioning.

The primary endpoint is change from baseline in flow-mediated dilation after 24-hour ischemic conditioning with a blood pressure cuff. The registry describes flow-mediated dilation as a common, non-invasive way to assess vascular endothelial function. It measures the brachial artery’s responsiveness through the percentage increase in diameter following a brief period of occlusion.

The outcome is classified as continuous, and its stated parameter is the mean, with standard deviation as the listed measure of dispersion. Its unit is recorded as percentage of baseline. The timeframe is baseline and post 24 hour conditioning. In broad terms, this endpoint uses an observable change in artery diameter as an indicator of vascular responsiveness; it is not itself a direct measurement of every aspect of endothelial function.

General statistical interpretation: a before-and-after endpoint is intended to characterize how measurements in the study group differ across the specified time points. The mean describes the group’s central value, while the standard deviation describes the spread of individual values around that mean. A mean change alone would not show how consistent individual responses were, and a standard deviation alone would not quantify the precision of the mean estimate.

The registry record does not report baseline or post-conditioning means, standard deviations, an estimated change, or a confidence interval. It also does not provide a numerical result for the primary endpoint. The endpoint definition explains what was intended to be measured, but it does not establish the size or direction of the observed change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General statistical explanation: the endpoint is continuous, meaning it is expressed on a measurement scale rather than as a count of events. The registry specifies a mean and standard deviation as the intended descriptive summaries. The mean gives a central group value. The standard deviation conveys how dispersed participant measurements are around that group value. Neither statistic is available numerically in the registry record for this endpoint.

What would a change estimate describe?

For a before-and-after question, a change estimate describes the contrast between measurements taken at the specified time points. Because the study is single group, the central question is framed around measurements at baseline and after 24-hour conditioning, not around a difference between two randomized arms. General statistical explanation: when the same participants contribute measurements at both time points, the within-participant relationship can matter. An analysis that uses that pairing may have different precision from one that treats the measurements as if they came from unrelated groups. The registry record does not report the statistical method used to analyze the endpoint, so it is not possible to say whether or how the within-participant structure was incorporated.

What do standard deviation and confidence interval mean?

General statistical explanation: a standard deviation describes variability among measurements, while a confidence interval describes uncertainty around an estimated quantity under the assumptions of the method used. They answer different questions. A wide spread of individual values does not by itself determine the precision of a group estimate; the amount of information and the analysis method also matter. The registry lists standard deviation as the dispersion measure but reports no numerical standard deviation or confidence interval. It therefore offers no basis for judging the precision of the endpoint estimate.

What would a significance test tell a reader?

General statistical explanation: a significance test assesses how compatible the observed data are with a specified null hypothesis under the test’s assumptions. A p-value is not a measure of effect size, clinical importance, or the probability that a hypothesis is true. Interpretation also depends on the analysis plan, endpoint definition, and data quality. The registry record lists zero analyses and does not report a p-value, test statistic, or named statistical test. No conclusion about statistical significance can be drawn from the posted record.

How should the planning assumptions be read?

The registry describes sample-size planning illustrations as based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the target effect is a stated proportion of the observed effect. These are planning assumptions, not findings from the enrolled participants. They do not represent observed power, and they do not change the registered single-group design into a two-arm trial. The numerical planning outputs and the observed effect used for them are not reported in the registry record.

General statistical explanation: planning calculations estimate how much information may be needed to detect a prespecified effect under selected assumptions. A calculation based on an effect observed in the same study can be especially dependent on that estimate. It should not be presented as a measure of the study’s observed ability to detect an effect. Here, the record explicitly characterizes the calculations as planning illustrations, and no numerical outputs are available in the record for interpretation.

Why does over-dispersion matter?

General statistical explanation: over-dispersion arises when count data vary more than a model assumes, which can make uncertainty appear too small if the extra variability is ignored. That issue is principally relevant to count outcomes and count-based models. The primary endpoint in this study is continuous flow-mediated dilation, not a count outcome. The registry record does not identify an over-dispersion analysis or a count model for the primary endpoint, so this concept should not be treated as a reported feature of the study analysis.

The registry also does not report the analysis population, the handling of missing measurements, model covariates, distributional checks, or sensitivity analyses. These details would help readers assess how the endpoint was analyzed and how robust a result might be. Without the numerical results and analysis methods, statistical interpretation must remain descriptive of the registered question and limited to what the record documents.

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.

R code and output

arm <- c("Intervention")
n   <- c(22)
m   <- c(6.6)
sp  <- c(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  Intervention  22  6.600  2.000  5.713  7.487

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. The listed primary outcome concerns change in flow-mediated dilation after 24-hour conditioning. The record does not report additional outcome analyses, multiple comparisons, or a multiplicity adjustment. Because no analysis results or detailed statistical analysis plan are reported in the registry record, it is not possible to determine whether any adjustment was planned or used outside the information recorded there.

Missing-data handling is also not reported in the registry record. There is no account of how many participants contributed measurements at each time point, whether any measurements were unavailable, or how missing values would be handled in an analysis. Enrollment is listed as 22, but that number alone does not establish how many paired baseline and post-conditioning observations were available for the primary endpoint.

The analysis population is not reported in the registry record. The record does not state whether the primary analysis included all enrolled participants, only those with complete measurements, or another defined group. It also does not describe protocol deviations, exclusions, or sensitivity analyses. These omissions limit assessment of possible selection effects and of how closely any analysis might reflect the enrolled group.

These are reporting gaps, not evidence that missing data or multiplicity problems occurred. The record does not provide enough detail to evaluate those issues, nor does it provide an endpoint analysis to interpret.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry lists an intervention group with 22 participants at risk for serious adverse events and zero affected. It also lists 22 participants at risk for other adverse events and zero affected. Deaths are listed as zero. No serious adverse event terms are listed.

These entries describe the safety counts recorded in the registry. They do not provide event-level descriptions, timing, severity beyond the serious-versus-other categories, or information about how events were collected or assessed. The counts should be read as the posted record, not as proof that no unrecorded events occurred.

General statistical explanation: an event count and its denominator are descriptive. A count of zero in a study group does not by itself establish that an event is impossible or that a procedure is free of risk; interpretation depends on the size and follow-up of the observed group and the completeness of event ascertainment. The registry does not report further details needed to assess those matters. The safety entries therefore summarize what was recorded but do not support broader conclusions about safety.

13. What the Result Does, and Does Not, Mean

The record documents a completed, single-group study intended to examine flow-mediated dilation before and after 24-hour ambulatory blood pressure monitoring. It identifies the primary endpoint, its measurement concept, and the planned descriptive form as a mean with standard deviation. It also records enrollment of 22 participants and the study status as COMPLETED.

The posted record does not report numerical results for the primary endpoint. It does not show whether flow-mediated dilation changed, the direction or magnitude of any change, or the precision of an estimate. No significance test or confidence interval is reported. Thus, the registry record does not support a conclusion about the observed endpoint result.

The design is single group, not a randomized comparison with a control arm. General statistical interpretation: a before-and-after observation can describe change over time among measured participants, but it cannot by itself separate the effect of the intervention from other influences that may also vary over time. Without a separate comparison group, causal interpretation is more limited than in a randomized controlled comparison. In this record, the absence of outcome results further prevents even a descriptive account of the direction of change.

The safety entries list zero serious adverse events, zero other adverse events, and zero deaths among the recorded group. Those figures are registry counts and should not be extended into a general claim about risk beyond the recorded observations.

Overall, the record establishes what question was registered and how the endpoint was described, but it does not report the numerical outcome or analysis needed to determine what the measurements showed. It should not be read as evidence for or against an effect on flow-mediated dilation.

14. Why This Trial Matters Statistically

This study illustrates why a clearly named endpoint and a reported result are both necessary for statistical interpretation. The registry defines flow-mediated dilation as a measure of brachial artery responsiveness and specifies baseline and post-conditioning measurements. Those details identify the intended question. But without the numerical values and an analysis, readers cannot assess the direction, size, variability, or precision of the observed change.

The single-group structure is also important. A before-and-after design can be useful for describing within-group measurements, but it does not provide a separate control trajectory. General statistical explanation: change over time can reflect the intervention, measurement variability, or other time-related influences. A comparison group can help distinguish these possibilities when it is appropriately designed and analyzed. The registry does not list such a group, so a causal contrast is not available from the registered design.

The record further demonstrates the distinction between a study’s design and planning assumptions. Its sample-size illustrations use assumptions about equal allocation between two arms, while the trial is registered as single group. Planning calculations are not observed power and do not substitute for observed endpoint results. Keeping those ideas separate prevents a hypothetical design calculation from being mistaken for evidence about the trial’s findings.

Finally, zero listed analyses and the lack of reported outcome values make transparent reporting especially consequential. Readers need the actual estimates, uncertainty, analysis methods, and information about missing measurements to judge the evidence. In this case, the registry record communicates the intended measurement and basic design, while leaving the result and its statistical interpretation unavailable.

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 principal limitation for interpreting this trial from the registry record is that numerical primary outcome results are not reported. Baseline and post-conditioning values, the estimated change, variability, and uncertainty are unavailable. The record also lists zero analyses, so it does not provide a statistical test or explain how the endpoint was analyzed.

The registered design is single group, with no separate comparator. As a result, the study is not described as a randomized, like-for-like comparison. A baseline measurement may provide a reference for a later measurement, but it does not supply the counterfactual information that a control group could provide. This limits causal interpretation independently of the missing numerical results.

The record lists 22 enrolled participants but does not report participant characteristics, the number with measurements at both time points, or the analysis population. Missing-data handling, protocol deviations, and sensitivity analyses are not reported in the registry record. These omissions make it difficult to assess completeness of the endpoint data and the population represented by any analysis.

The primary endpoint is described as a percentage of baseline and as a mean with standard deviation, but the record does not provide the corresponding values or define further analysis details. The statistical analysis plan, model, and assumptions used for any endpoint analysis are not reported in the registry record. The planning assumptions describe a two-arm calculation, which should not be confused with the registered single-group design. These limitations leave the study question identifiable but the outcome evidence and its precision unassessable from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: 24-hour Blood Pressure Measurements and Ischemic Conditioning — NCT03303404.
• Registry record last updated 2020-12-22; status last verified 2020-12.
• Results first posted 2020-12-22.
• 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.

19. Record Summary

NCT03303404 is a completed, single-group study of ambulatory 24-hour blood pressure monitoring and flow-mediated dilation. Enrollment is listed as 22. Allocation is recorded as NA, masking as none, and phase as NA. The study start date is 2017-09-12, and primary completion is recorded as 2018-09-20.

The primary endpoint is change from baseline in flow-mediated dilation after 24-hour ischemic conditioning with a blood pressure cuff. The registry describes the measure as brachial artery diameter responsiveness following brief occlusion and specifies a mean with standard deviation. Numerical endpoint results and analyses are not reported in the registry record.

The registry lists zero serious adverse events, zero other adverse events, and zero deaths in the intervention group. It does not report detailed missing-data handling or the analysis population.