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 Exploration of Pupil Dilation in Horner's Patients Taking Flomax (NCT03615508), a na phase 4 study. The primary outcome is Pupil Size Measurements.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03615508 |
| Phase | Phase 4 |
| Condition | Horner Syndrome |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Denver Health and Hospital Authority |
| Results posted | Yes |
2. Clinical Question
Population
Patients with Horner syndrome who had ever taken an alpha blocker, such as tamsulosin, were the intended population. The registry record says the study was incomplete, with one participant enrolled. Further eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
Participants were to receive 10% phenylephrine in each eye during an eye examination. The record describes this as the drug used to dilate the pupil, followed by measurement of pupil size.
Comparator
There was no separate comparator group. The study is listed as single-group, with allocation marked NA. The record does not describe a placebo, an untreated eye, or a comparison with another intervention.
Primary question
The primary outcome was pupil size measured in each eye 20-30 minutes after 10% phenylephrine was placed in each eye. The clinical question was whether pupil dilation measurements could be recorded in the intended population after administration. No measurements or analysis results are reported, so the record does not answer how much dilation was observed.
The study description frames the examination as similar to dilation during a yearly eye examination, with pupil measurements recorded. It concerns the response measured after phenylephrine in a specific population, not a comparison of treatments. The registry record does not report a prespecified threshold for interpreting a pupil-size measurement, nor does it state how measurements would be summarized across eyes or participants.
3. Trial Design
The registry identifies this as a Phase 4, single-group study sponsored by Denver Health and Hospital Authority. Allocation is listed as NA and masking as none. The intended design involved patients receiving 10% phenylephrine in both eyes, followed by pupil-size measurement. There was no randomized comparison, and the registry explicitly notes that any arms are not a like-for-like control comparison.
The study began on 2018-09-21, and its primary completion date is listed as 2019-05-01. Its current status is terminated. The registry does not report why the study was terminated, so the status alone does not establish why data collection stopped or whether a particular planned procedure was completed. The record describes the study as incomplete and reports one participant enrolled.
The primary outcome was pupil size measured in each eye 20-30 minutes after phenylephrine was placed in each eye. The record does not state the measurement unit, instrument, measurement procedure, or planned summary statistic. It also does not report the protocol, a sample-size justification, or a detailed statistical analysis plan.
Only one participant was enrolled, and the registry states that data are not reported for that participant for privacy reasons. No analyses are listed. As a result, the record contains a description of the intended design and endpoint but no posted outcome values with which to assess the pupil response. The study's single-group structure would in any case address a different question from a controlled trial: it could describe measurements after phenylephrine, but could not by itself estimate a treatment contrast against a concurrent control group.
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% Phenylephrine |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Study incomplete. Only 1 subject enrolled and data not reported for 1 participant for privacy reasons.
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.
Population: Study terminated, no patients analyzed; Data not reported for 1 participant for privacy reasons.
| Characteristic | Unit | 10% Phenylephrine |
|---|---|---|
| Participants analysed | 0 | |
| Age, Categorical: <=18 years | — | |
| Age, Categorical: Between 18 and 65 years | — | |
| Age, Categorical: >=65 years | — | |
| Sex: Female, Male: Female | — | |
| Sex: Female, Male: Male | — | |
| Region of Enrollment: United States | participants | — |
6. Primary Endpoint
The registry lists the primary outcome as Pupil Size Measurements, measured over 20-30 minutes after 10% phenylephrine has been placed in each eye..
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is pupil size measured in each eye at the eye examination, 20-30 minutes after 10% phenylephrine was placed in each eye. Pupil size is the direct measurement named in the study description: the intervention is intended to dilate the pupil, and the outcome records its size after administration. The endpoint therefore describes a physical measurement at a specified post-administration time, rather than a patient-reported outcome or a clinical event.
The registry record gives no unit for pupil size and does not report the instrument, measurement technique, baseline pupil size, or a rule for combining measurements from the two eyes. It also does not say whether the primary analysis would use each eye separately, summarize the two eyes for a participant, or compare post-dose measurements with another reference. Those details matter because the eye-level observations from one participant are not automatically independent of one another.
General statistical context: an endpoint should correspond closely to the question a study intends to answer and should be measured in a defined way. A stated measurement time can make results more interpretable by clarifying when the observation is taken. Here, the specified timing is 20-30 minutes after administration, but the absence of reported measurements means the endpoint's observed distribution, variability, and precision cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted registry information establishes the study's purpose and planned measurement, but it does not contain pupil-size results. The study enrolled one participant, and the record says data for that participant are not reported for privacy reasons. Consequently, there is no posted estimate of pupil dilation, no measure of variability, and no statistical comparison to interpret. The absence of results is not evidence that a particular amount of dilation did or did not occur.
The record lists no analyses. It therefore contains no reported confidence interval, p-value, or other inferential result for the primary endpoint. No recalculated result can be derived from the posted information because there is no outcome summary to recalculate. Similarly, the record does not provide an estimated effect that could be used to assess its magnitude or precision.
General statistical context: an estimate describes the observed quantity in a sample, while a confidence interval expresses uncertainty around an estimate under specified assumptions. A p-value, when calculated as part of a defined analysis, addresses compatibility between data and a statistical model; it does not by itself describe the size or clinical importance of an effect. None of these concepts can substitute for unreported outcome data. Without an observed pupil measurement or an analysis population, there is no basis for assessing sampling uncertainty or distinguishing a stable pattern from a chance observation.
The single-group design also limits the kind of inference that could be made even if measurements were available. Measurements after phenylephrine could describe the observed response in enrolled participants, but without a concurrent comparison group they would not isolate a contrast between phenylephrine and an alternative. No baseline measurement or untreated comparison is described in the registry record. These limitations concern the design; they are separate from the immediate absence of reported outcome data.
Planning assumptions associated with sample-size illustrations describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of an observed effect. Those assumptions are not a description of this single-group study's design or a report of its analysis. Since no observed effect is reported, such planning illustrations cannot be read as evidence about the study's precision or as observed power. The registry does not report the study's own sample-size justification.
The adverse-event record lists zero participants at risk and zero affected for serious and other events, as well as zero deaths. It does not explain the zero-at-risk entries alongside the reported enrollment. Those entries should not be treated as a complete safety assessment or as proof that no events occurred. The data available in the record are too limited to support that interpretation.
9. Statistical Methods Explained
General statistical context: statistical methods are useful only when their inputs, target question, and assumptions align with the design and reported data. The registry describes a single-group study, a measurement-based primary endpoint, and one enrollee, but lists no analysis. It does not provide values on which to demonstrate an endpoint analysis. The concepts below explain how such data are commonly considered; they do not describe analyses reported for this study.
What does a single-group design estimate?
A single-group study can describe measurements among participants who receive the study intervention. If outcome values and a prespecified summary are available, an analysis might describe the observed pupil size or its distribution at the specified time. A single-group result does not, on its own, estimate the difference between receiving an intervention and receiving no intervention or an alternative. That contrast requires a defensible comparison. The record lists no comparator and no randomized allocation.
In a controlled study, random allocation can help make groups comparable on average, subject to the study's conduct and size. This study is not described as randomized, and its allocation is NA. It would therefore be inappropriate to interpret it as a randomized comparison or to infer a between-group treatment effect. No arm-to-arm effect estimate is reported.
How should measurements from both eyes be considered?
The outcome description calls for a pupil measurement from each eye. General statistical context: two measurements from the same participant may be correlated because they share participant characteristics and study conditions. Treating correlated eye measurements as if they came from unrelated participants can make uncertainty appear smaller than it is. Appropriate analysis depends on the scientific target and the measurement plan; options in general include a participant-level summary or a method that accounts for within-participant dependence. The registry record does not say which approach was planned, and no eye-level results are reported.
The record also does not identify a baseline measurement or a comparison eye. Therefore, a change-from-baseline analysis or a paired-eye contrast cannot be assumed. The stated endpoint is pupil size after administration, not a reported change score. The instrument, measurement unit, and procedure for resolving repeated or inconsistent readings are also not reported in the registry record.
What do uncertainty measures require?
General statistical context: a confidence interval combines an estimate with an assessment of uncertainty, based on a statistical model and assumptions about the observations. Its width depends on factors such as the amount and variability of data and the analysis structure. A p-value is calculated relative to a null model and an analysis specification. Neither measure can be recovered from a study description alone. Because the registry reports no pupil values and no analyses, there is no estimate or uncertainty interval to interpret and no p-value to report.
With a very small amount of data, estimates can be highly sensitive to individual observations, and assumptions about the outcome distribution are difficult to evaluate. Here, no outcome values are available, so even a descriptive assessment of the measurement's range or variability is not possible. General statistical context: over-dispersion refers to variability greater than a model assumes. It matters when a model's uncertainty calculation depends on a variance assumption, but there is no reported outcome distribution in this record with which to assess over-dispersion or choose a model on that basis.
What are the planning illustrations?
The stated planning assumptions describe a hypothetical two-arm calculation using a two-sided significance level of 0.05, equal allocation, and a normal approximation. The target effect is described as a fraction of the observed effect. For non-time-to-event outcomes, the stated convention is participants per arm; time-to-event calculations use a total event count. These are planning conventions, not results from this study. The study itself is listed as single-group, not as an equally allocated two-arm trial.
A planning illustration based on an observed effect is sensitive to that effect estimate. It is not an observed power calculation, and it does not establish that the study had a particular probability of detecting an effect. In this record, the primary outcome values and observed effect are not reported, so the planning assumptions cannot be connected to an observed pupil-size result. The registry record does not report the trial's own sample-size justification or enough information to assess how its enrollment target was chosen.
What can the posted analysis establish?
The record lists zero analyses and gives no results for the primary endpoint. It therefore supports description of the intended measurement and study structure, not estimation of a pupil response. General statistical context: analysis decisions are most interpretable when specified before results are examined, including the outcome summary, analysis population, handling of missing data, and any adjustment for multiple comparisons. Those decisions are not reported in the registry record. They should not be reconstructed from the study title or the fact that the trial was terminated.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure and no analyses. It does not report a multiplicity plan, such as how multiple outcomes, time points, or comparisons would be handled. Although one primary endpoint is listed, the record does not establish whether additional exploratory outcomes or analyses were planned. It would be inappropriate to infer an adjustment method or to assume that no other analyses were intended.
Missing data are central to interpreting this record. The study is described as incomplete, and the registry states that one participant was enrolled but that data for that participant are not reported for privacy reasons. Thus, enrollment is documented, but no primary outcome value is available in the posted results. The record does not report whether the measurement was collected, whether it was withheld only from public reporting, or how the missing result would be treated in an analysis.
The record does not specify an analysis population, imputation method, missing-data assumption, or sensitivity analysis. General statistical context: missing-data methods rely on assumptions about why values are unavailable and on the role of the outcome in the analysis. Those assumptions cannot be checked. It is not possible to distinguish a measurement that was never collected from one that was collected but not released, based on the registry description alone.
The adverse-event entries list zero participants at risk and zero affected for serious and other events, with zero deaths. The relationship of those entries to the reported enrollment is not explained. The record also does not describe adverse-event collection methods or an analysis population for safety outcomes. Accordingly, the entries do not support a conclusion about the frequency or absence of adverse events.
11. What the Result Does, and Does Not, Mean
The registry record documents an intended measurement of pupil size after 10% phenylephrine in patients with Horner syndrome who had ever taken an alpha blocker. It identifies a measurement time of 20-30 minutes after the drug was placed in each eye and reports that one participant enrolled. These details clarify the study question and planned observation, but they do not provide an observed outcome.
No pupil-size data are reported for the participant, for privacy reasons, and the study is described as incomplete. The posted results therefore do not establish the amount of dilation observed, the variation in measurements, or the precision of any estimate. They do not show a statistical test or comparison. No conclusion about the direction or size of an effect can be drawn from the absence of outcome values.
The single-group design means that even a reported post-administration measurement would primarily describe observations in the enrolled participants. Without a comparator, the design would not by itself estimate how measurements differ from those under another intervention or no intervention. The registry does not report a baseline measurement, so a change from baseline should not be inferred either.
The record's adverse-event entries show zero at risk and zero affected in the listed categories, but the denominator is not reconciled with the enrollment count. These entries are not enough to establish that no adverse events occurred or to characterize safety. The terminated status likewise does not reveal why the study stopped, and no reason is reported in the registry record.
General statistical context: a small or unavailable dataset can leave a question unresolved; it is not equivalent to a finding of no effect. Likewise, planning assumptions are not observed results, and a hypothetical sample-size calculation is not evidence that a study was adequately powered. The appropriate interpretation is limited to the study's documented design, enrollment, status, and absence of publicly reported outcome data.
12. Why This Trial Matters Statistically
This study illustrates the distinction between a clearly stated measurement question and an answer supported by analyzable data. The registry names the population, intervention, outcome, and measurement timing, but reports one enrollee and no pupil measurements. A precise endpoint description is useful for understanding what investigators intended to observe, yet it cannot replace the observations themselves.
The design also highlights why the target of inference matters. A single-group study can describe outcomes in participants who receive the intervention, while a comparative claim requires an appropriate comparator and analysis. The record lists no comparator and no randomized allocation. Even if measurements had been posted, those design features would constrain interpretation to the observed group rather than a treatment contrast.
Measurement structure matters as well. The endpoint calls for observations from each eye, which belong to the same participant. General statistical context: analyses should account for the dependence among observations when measurements are clustered within a person. The registry does not report a plan for combining or modeling the two eye measurements, making it impossible to assess the intended handling of that structure.
Finally, the record demonstrates the importance of distinguishing enrollment, outcome availability, and analysis. Enrollment does not mean a result is available for interpretation. Here, the stated privacy reason for not reporting participant data leaves the primary outcome unevaluable from the public record. No analyses are listed, and the termination reason is not reported. Statistically, the main conclusion is a limit on what can be learned from this record, rather than an estimate of pupil response.
13. 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 main limitation is that the primary outcome is not reported. The registry describes one participant as enrolled and says that data for that participant are not reported for privacy reasons. Because the study is also described as incomplete, the available record does not establish whether the measurement was collected, whether other planned study procedures were completed, or whether the absent public result reflects data collection or reporting.
Enrollment of one participant leaves little basis for describing variation across participants, and no outcome values are available in any case. The record provides no pupil-size unit, measurement instrument, detailed measurement procedure, baseline value, or rule for summarizing the two eyes. These omissions prevent assessment of measurement precision and of how an eye-level observation would map to a participant-level endpoint.
The study has no comparator and is not randomized. This limits what the design could establish about differences attributable to the intervention, even if outcome values were available. The registry does not report a prespecified analysis plan, analysis population, missing-data approach, multiplicity strategy, or sample-size justification. The reason for termination is also not reported in the registry record.
The adverse-event entries list zero at risk and zero affected, but the registry does not explain those entries in relation to the reported enrollment. They should not be read as a complete account of safety outcomes. Collectively, these limitations mean the posted record supports a description of study intent and conduct, but not an estimate of the primary outcome or a conclusion about effects.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Exploration of Pupil Dilation in Horner's Patients Taking Flomax — NCT03615508.
- Registry record last updated 2022-03-03; status last verified 2022-02.
- Results first posted 2020-10-14.
- 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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17. Record Summary
NCT03615508 is a Phase 4, single-group study sponsored by Denver Health and Hospital Authority. It concerns pupil dilation in patients with Horner syndrome who had ever taken an alpha blocker, with 10% phenylephrine placed in each eye and pupil size measured 20-30 minutes later. The registry lists no comparator, no masking, and one participant enrolled. The study began on 2018-09-21, had a primary completion date of 2019-05-01, and is listed as terminated.
The study is described as incomplete. Data for the one participant are not reported for privacy reasons, and no analyses are listed. The registry does not report pupil-size results, a reason for termination, or a detailed analysis plan. The record therefore defines the intended measurement but does not provide an outcome estimate to interpret.