Prospective Study to Compare the Efficacy of E.G.Scan to Detect Barrett's Esophagus Compared With Standard Endoscopy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prospective Study to Compare the Efficacy of E.G.Scan to Detect Barrett's Esophagus Compared With Standard Endoscopy (NCT02066233), a non-randomized na study. The primary outcome is Median Tolerability Score on 10-point Visual Analog Scale (VAS).

2. Clinical Question

3. Trial Design

The study, NCT02066233, is titled “Prospective Study to Compare the Efficacy of E.G.Scan to Detect Barrett's Esophagus Compared With Standard Endoscopy.” Mayo Clinic is listed as the sponsor. The registry record gives a nonrandomized allocation, no masking, and a parallel model. The phase is listed as not applicable. The status is completed, with a recorded enrollment of 100.

The record describes two participant groups: subjects with Barrett’s esophagus and subjects with reflux and/or heartburn. In both group descriptions, all subjects are to receive EG Scan II transnasal endoscopy followed by standard endoscopy. Thus, the record’s group labels distinguish participant categories, while the listed procedure sequence is the same for both. It does not describe random assignment, blinding, or a group receiving only one of the procedures. Further detail on how the study operationalized the comparison is not reported in the registry record.

The study summary identifies visualization of the esophagus as the broad purpose of the evaluation. However, the posted primary endpoint is median tolerability score on a 10-point visual analog scale within 48 hours. A secondary outcome is participant preference for either EG II Scan or standard endoscopy. The registry record does not report results for either outcome, nor does it give a diagnostic accuracy result.

The recorded study start is 2014-03, and primary completion is listed as 2015-10. These dates describe the registry record; they do not establish when each participant underwent the procedures or completed the outcome assessment. The protocol’s detailed statistical plan, including how the two procedures’ results were intended to be compared, is not reported in the registry record.

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.

EG Scan II (Day 1)

Reasons for not completing this period:

Standard Endoscopy (Day 2)

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 Median Tolerability Score on 10-point Visual Analog Scale (VAS), measured over Within 48 hours.

The primary endpoint is the median tolerability score on a 10-point visual analog scale, assessed within 48 hours. The scale is described as ranging from 0 for the “worst experience” to 10 for the “best experience.” It is a participant-reported measure of how the procedure was experienced. The registry record does not specify whether participants gave a separate score for each procedure, whether the score represented the overall study experience, or how the median was to be calculated if scores were missing.

A median describes the middle of a set of observations when they are ordered. It can be useful for a bounded rating scale because it indicates a typical response without requiring the scores to follow a particular distribution. It does not, by itself, describe how widely participant scores vary. The registry record identifies the full range as the dispersion measure, but endpoint values and ranges are not reported.

Tolerability is relevant to a comparison of procedures because participants’ experiences may differ even when the procedures are being considered for the same clinical purpose. This endpoint does not directly measure visualization quality or the ability to detect Barrett’s esophagus. Those questions would require outcomes about diagnostic findings and an appropriate reference standard; such results are not reported in the registry record. The listed secondary outcome, participant preference, captures another aspect of experience, but its results are also not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the median represent?

In general, a median is the midpoint of ordered observations: half of the observed values are at or below it and half are at or above it, allowing for ties and the details of the calculation. Unlike a mean, the median is not pulled as strongly by especially high or low observations. That can make it a useful summary for a rating scale, particularly when the spacing between adjacent response categories cannot be assumed to represent equal increments in experience.

Here, the endpoint is defined as a median score on a 10-point visual analog scale, assessed within 48 hours. The scale anchors give direction to the rating: 0 is the worst experience and 10 the best. The registry record does not post the median or the full range, so neither the central rating nor the observed spread can be described. A median alone would not reveal whether most responses clustered near it or were widely dispersed; the range would give the lowest and highest observed scores but would not show the full distribution.

What would a procedure comparison require?

In general, a comparative analysis must match the structure of the observations. When different participants receive different procedures, a comparison typically treats the groups as independent. When each participant experiences both procedures, the two ratings are linked within each person; an analysis can account for this pairing. Pairing can reduce the influence of between-person differences, but it does not remove potential order effects, carryover, or other sources of bias.

The registry record labels the design nonrandomized and parallel, while both arm descriptions say participants receive EG Scan II followed by standard endoscopy. It does not clarify whether each person provides separate tolerability scores for both procedures, which score is summarized, or what statistical comparison is planned. The analysis methods and comparative result are not reported in the registry record. It is therefore not possible to determine whether a paired or independent-group method was used, or whether the analysis accounted for the procedure sequence.

How should uncertainty be assessed?

In general, an estimate describes the size and direction of an observed effect, while a confidence interval describes the range of values reasonably compatible with the data under the model used. A narrow interval indicates greater precision than a wide interval, although interpretation also depends on the outcome and design. A p-value, when reported, measures how compatible the data are with a specified null model; it does not quantify the probability that the null hypothesis is true or the importance of an effect.

No confidence interval, p-value, test statistic, or comparative estimate for the primary outcome is reported in the registry record. Without these results, neither statistical uncertainty nor the strength of evidence for a difference can be evaluated. A statistical method cannot repair missing information about what was measured, how many observations were analyzed, or how outcomes from the two procedures were linked.

What do the planning illustrations mean?

In general, a sample-size calculation estimates how many observations might be needed under specified assumptions about an effect, variability, significance level, allocation, and statistical method. Such a calculation is a planning exercise; it is not a result observed in a trial and is not “observed power.” Planning illustrations associated with the posted material use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect set as a stated fraction of the observed effect. They are not the trial’s own design justification.

The registry record does not report the protocol’s sample-size assumptions or justification. It also does not report a primary outcome estimate from which a reader could assess the effect used in an illustration. Any planning number should therefore be read as conditional on the stated assumptions, not as an observed trial finding or evidence that the completed study had adequate precision. No extra sample-size calculation can be reconstructed from the registry record’s posted endpoint information.

Why does over-dispersion matter in general?

For outcomes that are counts, a statistical model may assume a particular relationship between the mean and the variability. Over-dispersion occurs when the observed variability is greater than that assumption allows. If it is ignored, standard errors can be too small and confidence intervals too narrow. This is a general consideration for count outcomes, not a method reported for this study. The primary outcome is a rating-scale median, and the registry record does not describe a count-outcome analysis.

More generally, statistical interpretation depends on the measurement scale, comparison structure, missingness, and prespecified analysis. In this study, those methodological details are not reported in the registry record. The outcome definition can be described, but no inferential conclusion can be drawn without the results and analysis details.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: median tolerability score as the primary outcome and participant preference for either EG II Scan or standard endoscopy as a secondary outcome. When a study evaluates multiple outcomes or multiple comparisons, there can be more than one opportunity to observe a result that appears statistically notable by chance. In general, a statistical plan may address multiplicity by specifying a hierarchy, adjusting inference, or treating some outcomes as exploratory. The approach used in this study is not reported in the registry record.

The record lists no analyses. It does not provide a missing-data method, an analysis population, or the number of participants with an observed primary endpoint. It also does not explain whether participants who did not complete both procedures, did not return a rating, or had incomplete records were included or excluded. These details matter because a median computed from a subset may differ from one based on a broader set of participants, and missingness can affect how representative the observed responses are.

The enrollment figure is 100, while the safety entries list 44 at risk in each participant group. The registry record does not reconcile these counts or state whether they correspond to the same analysis population. They should not be used to infer the number included in either outcome analysis. Without group-specific endpoint counts, a prespecified multiplicity approach, and a description of missing-data handling, the completeness and inferential status of the outcome assessment cannot be established.

11. 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.

Most frequent non-serious adverse event terms

The safety record lists two participant groups: subjects with Barrett’s esophagus and subjects with reflux and/or heartburn. For each group, 44 participants are listed as at risk for serious adverse events, with 0 affected; deaths are listed as 0. For other adverse events, 44 are listed at risk and 44 affected in each group. These are the figures recorded for the safety categories and groups, not a description of event types or severity beyond the serious-versus-other distinction.

No serious adverse event terms are listed. The record does not describe the specific other adverse events, their timing, duration, seriousness, relationship to either procedure, or whether the same participants contributed to both group entries. It also does not explain how these safety denominators relate to the total enrollment of 100 or to the primary endpoint population. The safety figures therefore should be read as registry counts, without assuming causation or using them to infer comparative risk between the procedures. The absence of listed serious events does not supply information about tolerability scores or diagnostic performance.

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

The registry record documents a prospective study intended to compare EG Scan II transnasal endoscopy with standard endoscopy. It describes both procedures as being performed in sequence for subjects with Barrett’s esophagus and subjects with reflux and/or heartburn. It identifies a primary tolerability outcome and a secondary preference outcome. These design and outcome descriptions clarify what the study set out to examine, but they are not evidence of the results.

The posted primary endpoint is a median rating on a scale with stated anchors, assessed within 48 hours. The numerical median and full range are not reported in the registry record. Preference results are also not reported. Consequently, the record does not show which procedure participants found more tolerable, whether preferences differed, or how precise any observed comparison was. It does not report diagnostic accuracy or establish how well either procedure visualized the esophagus.

In general, a study’s title, rationale, and completion status do not replace outcome estimates. A useful interpretation of comparative results would require the observed scores, their variability or uncertainty, participant counts, and a clear account of how the procedure sequence was analyzed. The registry record does not report those details. The nonrandomized designation and absence of masking are relevant design features, but without results and methods they do not establish the direction or magnitude of any bias.

The safety counts record no serious adverse events among the listed participants at risk, while other adverse events are recorded for all participants at risk in each group. Specific event descriptions and attribution are absent, so these entries cannot be interpreted as evidence that an event was caused by either procedure or as a comparison of procedure-related risk.

In short, the registry record describes the study question, sequence of procedures, and intended outcomes, but does not provide the outcome analyses needed to answer the comparison. It supports no conclusion about whether the procedures differ in tolerability, participant preference, or diagnostic performance.

13. Why This Trial Matters Statistically

This study raises a useful statistical distinction between the question named in a study’s title and the endpoint reported as primary. The stated purpose concerns whether EG Scan II visualizes the esophagus as well as standard endoscopy, whereas the posted primary endpoint is a tolerability rating. These outcomes address different questions. A participant’s rating can inform a comparison of experience, but it is not itself a measure of diagnostic performance.

The record also illustrates why design labels should be read alongside procedural descriptions. It identifies a nonrandomized parallel model, yet describes participants in both groups as receiving EG Scan II followed by standard endoscopy. That sequence makes it important to know whether outcomes were measured separately for each procedure and how the comparison accounted for within-participant pairing and order. The statistical analysis is not reported in the registry record, so those issues cannot be resolved from the design label alone.

Finally, a completed status and an enrollment figure do not make a study’s findings interpretable when outcome estimates are absent. Readers need endpoint values, participant counts, measures of uncertainty, and a clear analysis population to judge the precision and scope of a comparison. The registry record lists the outcomes and safety counts, but not the primary or secondary outcome analyses. This makes the distinction between a study being registered as completed and results being available especially important for statistical interpretation.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation of the registry record for interpreting this study is the absence of numerical results for the primary and secondary outcomes. No median tolerability score, full range, preference result, effect estimate, confidence interval, or p-value is reported. The stated diagnostic purpose is not accompanied by a diagnostic accuracy result. These omissions prevent assessment of the direction, magnitude, and precision of any comparison.

Design and analysis details are also sparse. The record describes nonrandomized allocation and no masking, and it lists a parallel model. Yet both participant groups are described as receiving both procedures in sequence. The record does not explain how this structure was analyzed, whether distinct ratings were recorded for each procedure, or how sequence effects were addressed. The analysis plan, analysis populations, and missing-data methods are not reported.

The enrollment count of 100 is not reconciled with the safety entries of 44 participants at risk in each group. The number contributing to each outcome is not reported, and the record does not explain whether all enrolled participants completed the procedures or the assessment. The specific non-serious adverse events are also not described. Finally, the registry record does not include the study’s sample-size justification or detailed statistical plan. These gaps limit what can be inferred from the record; they do not establish that the study itself lacked those procedures or analyses.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Prospective Study to Compare the Efficacy of E.G.Scan to Detect Barrett's Esophagus Compared With Standard Endoscopy — NCT02066233.
• Registry record last updated 2017-07-06; status last verified 2017-06.
• Results first posted 2017-07-06.
• 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.

18. Record Summary

NCT02066233 is a completed, nonrandomized study sponsored by Mayo Clinic, with enrollment listed as 100. The recorded start is 2014-03 and primary completion is 2015-10. The study concerns EG Scan II transnasal endoscopy and standard endoscopy in subjects with Barrett’s esophagus and subjects with reflux and/or heartburn. Both group descriptions specify EG Scan II followed by standard endoscopy.

The primary outcome is median tolerability score on a 10-point visual analog scale within 48 hours; the secondary outcome is preference for either procedure. The registry record lists two outcome measures and no analyses. Outcome values and comparative results are not reported in the registry record. Safety entries list 44 participants at risk in each group, 0 serious adverse events, 0 deaths, and 44 affected by other adverse events in each group.