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 Characterization of Myocardial Blood Flow Measurements Using Lexiscan®™ (Regadenoson) (Lexiscan®™) Rubidium-82 Myocardial Perfusion PET: A Temporal-Dependency Investigation (NCT01919450), a randomized phase 4 study. The primary outcome is Measure Quantitated Myocardial Perfusion Reserve After a 4 Minute Delay in Lexiscan (Regadenoson).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01919450 |
| Phase | Phase 4 |
| Condition | Myocardial Blood Flow Reserve |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 80 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Timothy M. Bateman, MD |
| Results posted | Yes |
2. Clinical Question
Population
The registry record identifies myocardial blood flow reserve as the condition of interest. It does not describe the characteristics of the enrolled participants or give a more specific eligibility-defined population in the primary outcome record. Enrollment was 80, but the registry record does not report how those participants were distributed across the delay groups in the primary endpoint results.
Intervention
The study evaluates regadenoson followed by rubidium-82 myocardial perfusion PET imaging. Its central timing question is whether quantitative peak stress myocardial blood flow and myocardial blood flow reserve measurements vary with the delay between regadenoson injection and the start of the rubidium-82 infusion or imaging process. The four assigned delay times were 10 seconds, 1 minute, 2 minutes and 4 minutes.
Comparator
The comparator is the measurement obtained under another assigned delay condition. The registry describes randomized parallel groups for the 10 second, 1 minute, 2 minute and 4 minute delays. It does not report a separate usual-care or placebo comparison. The intended comparison concerns timing conditions, rather than a comparison of regadenoson with no regadenoson.
Primary question
The primary question is how myocardial blood flow reserve, defined in the record as the peak stress to rest ratio, is characterized after the different delays. The stated aim is to establish means and standard deviations for the four timing conditions and assess measurement consistency. The registry summary anticipates no or minimal difference, but that expectation is not a result. Numerical endpoint values and a statistical comparison are not reported in the registry record.
3. Trial Design
This is a randomized, parallel-group Phase 4 study listed as completed. The registry record lists enrollment of 80. Participants were assigned to one of four delay conditions: 10 seconds, 1 minute, 2 minutes or 4 minutes between regadenoson injection and the start of myocardial perfusion PET imaging. The record identifies regadenoson as a drug and rubidium-82 as radiation. It describes the assigned arms by their respective delay times.
The study is listed as having no masking. The registry record lists a start date of 2013-07 and a primary completion date of 2016-04. The sponsor is Timothy M. Bateman, MD. The record does not provide more detail about the randomization procedure, whether allocation was concealed, the practical conduct of imaging, or the number of participants who completed each measurement. Those details are not reported in the registry record.
The stated purpose was to evaluate the consistency of quantitative peak stress myocardial blood flow and myocardial blood flow reserve following the different delays. The primary endpoint is described as a continuous measure, with the mean and standard deviation intended to characterize the reserve ratio in each timing condition. Although the registry identifies a primary outcome, it lists zero analyses and does not post numerical results for that outcome. A randomized design can support comparisons between assigned conditions, but the design label alone does not establish that the analysis was conducted as randomized or indicate how missing measurements were handled.
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 | 10 Second Delay | 2 Minute Delay | 4 Minute Delay | 1 Minute Delay |
|---|---|---|---|---|
| STARTED | 20 | 20 | 20 | 20 |
| COMPLETED | 20 | 20 | 20 | 19 |
| NOT COMPLETED | 0 | 0 | 0 | 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 | 10 Second Delay | 2 Minute Delay | 4 Minute Delay | 1 Minute Delay | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 20 | 20 | 20 | 20 | 80 | |
| Age, Continuous | Years | 50.5 (SD 13.8) | 51.3 (SD 10.4) | 53.1 (SD 9.6) | 50.6 (SD 9.9) | 51.9 (SD 11.0) |
| Sex: Female, Male: Female | Participants | 14 | 6 | 10 | 15 | 45 |
| Sex: Female, Male: Male | Participants | 6 | 14 | 10 | 5 | 35 |
| Region of Enrollment: United States | participants | 20 | 20 | 20 | 20 | 80 |
6. Primary Endpoint
The registry lists the primary outcome as Measure Quantitated Myocardial Perfusion Reserve After a 4 Minute Delay in Lexiscan (Regadenoson), measured over 4 minutes.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Ratio |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is myocardial blood flow reserve, expressed as the peak stress to rest ratio. It is a continuous measure: a value represents the relationship between myocardial blood flow under stress and at rest. The registry record specifies the mean and standard deviation as the intended summary statistics and identifies the timeframe as 4 minutes. The outcome description also says the study aimed to establish these summaries for the 10 second, 1 minute, 2 minute and 4 minute delays.
Means describe the central value of a group’s measurements, while standard deviations describe how spread out individual measurements are around that mean. Considering both can help characterize measurement distributions across timing conditions. Similar means alone would not establish that measurements are consistent for individual participants: group averages can be alike even when individual values vary. The endpoint is relevant to the study’s stated timing question because it focuses on the stress-to-rest reserve measurement after regadenoson and PET imaging.
The endpoint description does not give a numerical mean, standard deviation, between-group contrast or uncertainty interval. Those results are not reported in the registry record. The stated objective of characterizing measurements should therefore be distinguished from evidence that the timing conditions yielded similar values.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a randomized comparison of four imaging-delay conditions and identifies myocardial blood flow reserve as the primary outcome. It does not report numerical results for that endpoint. There are no posted means, standard deviations, contrasts between delay groups, confidence intervals or hypothesis-test results in the primary outcome record. Consequently, the posted information does not show whether the reserve measurements were similar across delays, how large any differences were, or how precisely those differences were estimated.
The registry summary says that no or minimal difference between the four delay times was anticipated. This is a statement of expectation, not an observed finding. Without the outcome estimates and their uncertainty, it is not possible to assess whether the results were compatible with that expectation. Nor can a reader determine whether any observed differences, if present, would be small enough to matter for the measurement question.
The record lists zero analyses. This does not, by itself, establish that no analysis occurred; it means that no analysis entries are reported in the registry record. The endpoint description says that means and standard deviations were to be established, but the corresponding numerical results are absent. A result cannot be inferred from the listed study design, completion status, enrollment or anticipated direction.
Safety entries show zero serious adverse events reported as affecting participants in the 10 Second Delay, 2 Minute Delay and 4 Minute Delay groups. The 1 Minute Delay group lists one participant affected by a serious adverse event. Other adverse event counts are zero in the listed groups. These counts are descriptive and do not provide a statistical comparison. The record also lists Neck Pain at 5.0% among the top serious terms, without explaining how that term relates to the group-level serious-event figures. Death counts are not reported.
Overall, the registry provides the design, endpoint definition and some safety counts, but not the primary outcome estimates needed to interpret the timing comparison. No conclusion about consistency or equivalence can be drawn from the posted endpoint information alone.
9. Statistical Methods Explained
What does a mean describe?
For a continuous outcome such as myocardial blood flow reserve, the mean is an average that describes the center of the measured values within a group. The standard deviation describes the spread of those values around the mean. Together, these summaries can offer a basic picture of each delay group: the typical measured reserve and the degree of variation among measurements. They do not show the full distribution, and they do not reveal whether particular values or subgroups differ.
The registry record identifies the mean and standard deviation as the endpoint summaries, but does not report their numerical values. Readers therefore cannot compare the centers or spreads across the delay groups from the posted primary results. Even if group means were available, similarity of means would not necessarily imply close agreement for individual measurements. Assessing individual-level consistency may require methods that examine paired measurements or agreement directly; the registry record does not report such methods.
What would a comparison estimate?
A comparison between delay conditions would describe how the outcome differs between groups, according to a specified statistical model or contrast. The estimate answers a different question from the group means themselves: it quantifies the contrast, while an uncertainty interval describes the range of values reasonably compatible with the data and model. A narrow interval indicates greater precision than a wide interval. The registry record does not report contrasts or confidence intervals, so neither the magnitude nor precision of any timing difference can be assessed.
Because four timing conditions are named, an analysis could involve multiple pairwise contrasts or an overall test of differences. Those approaches answer different questions. An overall test addresses whether there is evidence of variation across conditions; pairwise contrasts identify differences for particular pairs. Neither approach is reported in the registry record. It would be inappropriate to assume which contrast was primary beyond the outcome description or to infer a method from the randomized design.
How should the stated expectation be read?
The record anticipates no or minimal difference between the delay times. To establish that measurements are sufficiently similar, a study generally needs a prespecified definition of what counts as an acceptably small difference and an analysis designed to assess that criterion. A conventional test that fails to detect a difference does not, by itself, demonstrate equivalence or similarity: lack of evidence for a difference can result from imprecise data. The registry record does not report an equivalence margin, a noninferiority margin, or a statistical procedure for evaluating the stated expectation.
These are general statistical principles, not descriptions of analyses known to have been performed in this study. The registry record does not report the statistical analysis plan, the model used for the continuous endpoint, covariate adjustment, assumptions checks or the handling of repeated or incomplete measurements. Those details cannot be inferred from the endpoint’s use of means and standard deviations.
What role does uncertainty play?
Observed estimates are subject to sampling variation: a different set of participants could yield different means and contrasts. Confidence intervals express uncertainty around an estimate under the assumptions of the analysis. They help distinguish a precise estimate from one that leaves substantial uncertainty about the size or direction of a difference. A p-value, when reported, addresses compatibility of data with a specified null model; it does not measure the size or practical importance of an effect. No p-value or confidence interval for the primary outcome is reported in the registry record.
Statistical significance and measurement consistency are not interchangeable. A statistically detectable difference might be small, while an inconclusive test might still leave important differences plausible. For a timing study whose stated aim is consistency, estimates and their precision, interpreted against a prespecified criterion for acceptable variation, would be central. That criterion and the necessary estimates are not reported in the registry record.
What do the safety counts convey?
Adverse-event counts are descriptive entries. The group-level figures indicate how many participants were listed as at risk and how many were listed as affected for serious and other adverse events. They are not adjusted comparisons and do not establish that one delay condition has a different safety profile from another. A zero count means no affected participants were entered for that category in the listed group; it does not establish that an event was impossible or that all events were captured. The registry record does not report methods for event collection, attribution, or comparative safety analysis.
The safety record includes a serious-term entry for Neck Pain at 5.0%, while the group-level affected counts differ across delay conditions and include zero entries in several groups. The record does not explain the relationship between the term-level percentage and the group counts. The percentage should therefore be read as a registry entry, not used to reconstruct an unreported group comparison.
The registry also describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Such sample-size calculations, when displayed, are planning illustrations and not observed power. The record does not report the trial’s own sample-size justification or enough numerical primary outcome results to interpret any recalculated planning values. No planning calculation can substitute for the missing endpoint estimates.
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 |
|---|---|---|---|---|
| 4 Minute Delay | 18 | 2.570 | 0.710 | 2.217 to 2.923 |
R code and output
arm <- c("4 Minute Delay")
n <- c(18)
m <- c(2.57)
sp <- c(0.71)
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 4 Minute Delay 18 2.570 0.710 2.217 2.92311. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary endpoint description and lists four outcome measures overall, but it lists zero analyses. The endpoint description concerns mean and standard deviation summaries of myocardial blood flow reserve under four delays. It does not report which comparisons, if any, were formally tested, whether there was an overall test followed by pairwise comparisons, or whether a particular contrast was designated as the principal inferential comparison. A multiplicity strategy is not reported in the registry record.
Multiplicity matters when several statistical questions are examined. Repeated testing can increase the chance of obtaining at least one apparently notable result by chance. Possible approaches include specifying a single primary comparison in advance, adjusting inference across a family of comparisons, or treating secondary comparisons as exploratory. These are general options, not methods attributed to this study. The record does not report a multiplicity adjustment or an analysis plan from which one could determine how multiple comparisons were handled.
The registry record does not report primary endpoint values by group, analysis populations, participant flow for the outcome, or the number of missing measurements. It also does not describe an intention-to-treat, per-protocol or other analysis population for the endpoint. Handling of missing data, exclusions after randomization, and sensitivity analyses are not reported in the registry record. Completion status and enrollment do not supply those details. Without them, readers cannot evaluate whether the reported endpoint results, if available elsewhere, would represent all randomized participants or a selected subset.
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 |
|---|---|---|---|
| 10 Second Delay | 0 | 20 | 0.0% |
| 2 Minute Delay | 0 | 20 | 0.0% |
| 4 Minute Delay | 0 | 19 | 0.0% |
| 1 Minute Delay | 1 | 20 | 5.0% |
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 |
|---|---|
| 10 Second Delay | 0 of 20 |
| 2 Minute Delay | 0 of 20 |
| 4 Minute Delay | 0 of 19 |
| 1 Minute Delay | 0 of 20 |
Most frequent serious adverse event terms
| Event term | Organ system | 10 Second Delay | 2 Minute Delay | 4 Minute Delay | 1 Minute Delay |
|---|---|---|---|---|---|
| Neck Pain | Musculoskeletal and connective tissue disorders | 0 of 20 | 0 of 20 | 0 of 19 | 1 of 20 |
Serious events with the highest arm-level rate: neck pain (5.0%).
The registry lists group-level counts for serious and other adverse events. For the 10 Second Delay group, 20 participants are listed as at risk and 0 as affected for serious events; the other-event count is also 0. For the 2 Minute Delay group, 20 are listed as at risk, with 0 affected for serious events and 0 for other events. For the 4 Minute Delay group, 19 are listed as at risk, with 0 affected for serious events and 0 for other events. For the 1 Minute Delay group, 20 are listed as at risk, 1 is listed as affected for a serious event, and 0 for other events.
These registry counts are not a comparative safety analysis. The record lists Neck Pain at 5.0% among the top serious terms, but does not explain how this term-level entry corresponds to the group counts. Death counts are not reported in the registry record. A zero listed count should be read as no affected participants recorded in that entry, not as proof that no event could occur or that the event was absent under every method of ascertainment.
13. What the Result Does, and Does Not, Mean
This study is relevant to a measurement question: whether the interval between regadenoson injection and rubidium-82 PET imaging is associated with the reported myocardial blood flow reserve measurement. The registry describes four timing conditions and defines reserve as the peak stress to rest ratio. Its stated aim is to characterize means and standard deviations under those conditions. That focus makes the design distinct from a trial asking whether a treatment improves a clinical outcome.
The record does not report numerical primary outcome results or a statistical comparison. It therefore does not establish that the measurements were consistent across delays, that one delay yielded a higher or lower value, or that any differences were negligible. The anticipated absence of or minimal difference is an expectation described in the registry summary, not evidence that the expectation was borne out.
Even when group averages are close, the degree of individual-level agreement and the uncertainty around the comparison matter. Conversely, a difference between group averages would need to be interpreted in light of its precision and a prespecified criterion for an acceptable difference. The registry record does not provide those estimates or criteria. Thus, the posted information does not support a claim of equivalence, noninferiority or practical interchangeability of the timing conditions.
The available safety entries describe recorded event counts, not the primary measurement question. They do not resolve whether timing affects the quantitative reserve measurement. The registry record is best read as documenting the study design, intended endpoint and limited safety information while leaving the main numerical results unavailable.
14. Why This Trial Matters Statistically
Timing can be an important part of quantitative imaging because the measurement is taken within a process that includes an administered agent and image acquisition. This study’s stated statistical question is whether myocardial blood flow reserve measurements are characterized consistently when imaging follows regadenoson after different delays. A randomized parallel design can structure a comparison of those timing conditions, while a continuous endpoint allows the magnitude and spread of measurements to be described.
The study also illustrates why a declared expectation of little or no difference is not enough to establish similarity. A useful statistical interpretation requires numerical estimates, uncertainty, and a definition of how much variation would be acceptable for the measurement purpose. A nonsignificant result, if one were reported, would not by itself demonstrate that the timing conditions produce sufficiently similar measurements. The registry record does not report the results or an equivalence criterion, so that distinction remains important.
There is also a distinction between group-level summaries and individual-level consistency. Means and standard deviations can describe central tendency and dispersion, but may not fully characterize how closely measurements agree for individuals. The record specifies those summaries but does not describe an agreement analysis. This makes the endpoint definition and the chosen analysis especially consequential for the stated consistency objective.
Finally, the record demonstrates the limits of interpreting trial registration entries when outcome results are absent. Design information can clarify what question was planned, but cannot replace estimates and their precision. Readers can identify the timing comparison and the intended endpoint, yet cannot determine the observed measurement pattern from the posted primary outcome information.
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 primary limitation for interpretation is that numerical results for the main endpoint are not reported in the registry record. Means, standard deviations, contrasts, confidence intervals and hypothesis-test results are absent, so the central timing comparison cannot be evaluated. The registry’s stated expectation of no or minimal difference cannot serve as evidence of similarity.
The record does not report the statistical analysis plan, the method used for comparisons, or whether the study used an equivalence or noninferiority framework. It also does not give a margin defining an acceptable difference. Although the outcome description calls for means and standard deviations, those summaries alone would not necessarily establish participant-level agreement. No agreement method is reported.
Participant characteristics, group-specific primary outcome counts, participant flow, missing endpoint data, analysis populations and handling of missingness are not reported in the registry record. The record lists enrollment of 80, but does not provide enough information to assess how many participants contributed measurements to each primary outcome analysis. Randomization is listed, but the randomization procedure and allocation concealment are not described.
The safety entries also have interpretive limits. The relationship between the Neck Pain term listed at 5.0% and the group-level serious-event counts is not explained, and death counts are not reported. These entries cannot support a comparative safety conclusion. Finally, the registry record does not report the trial’s own sample-size justification or whether interim analyses were conducted. Those details should not be inferred from completion status or the posted design information.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Characterization of Myocardial Blood Flow Measurements Using Lexiscan®™ (Regadenoson) (Lexiscan®™) Rubidium-82 Myocardial Perfusion PET: A Temporal-Dependency Investigation — NCT01919450.
- Registry record last updated 2018-08-16; status last verified 2018-07.
- Results first posted 2017-03-27.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
The registry record describes a completed, randomized, unmasked, parallel-group Phase 4 study of regadenoson and rubidium-82 myocardial perfusion PET. Enrollment is listed as 80. The assigned timing conditions were 10 seconds, 1 minute, 2 minutes and 4 minutes. The primary endpoint is myocardial blood flow reserve, defined as the peak stress to rest ratio, with mean and standard deviation specified as summaries.
The record states that the study aimed to characterize reserve measurements across delays and anticipated no or minimal difference. It lists zero analyses and does not report numerical primary endpoint results. Safety entries report serious and other adverse-event counts by group, and list Neck Pain at 5.0% among the top serious terms; death counts are not reported. The registry information therefore defines the question and design but does not permit assessment of the observed primary outcome comparison.