The Second-Generation MCCG for Upper Gastrointestinal Tract.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Second-Generation MCCG for Upper Gastrointestinal Tract. (NCT03977935), a randomized na study. The primary outcome is Circumferential Visualization of the Z-line.

2. Clinical Question

This is a device-comparison question, not a comparison of capsule examination with another diagnostic approach. The registry’s stated rationale is to evaluate the clinical application of a second-generation device with higher image resolution and frame rate. The primary endpoint concerns how much of the Z-line is visualized. Other registered outcomes concern such measures as examination time, image quality, manipulation, lesion detection, and capsule transit.

The record does not post the participant counts in the Z-line categories for either group, nor does it report a statistical comparison of those categories. As a result, the central comparative question cannot be answered from the posted results. The design and endpoint can be described, but the direction, magnitude, and precision of any observed difference are not reported in the registry record.

3. Trial Design

The registry identifies this study as a randomized, double-blind, parallel-group clinical trial comparing second-generation with first-generation magnetically controlled capsule gastroscopy. Changhai Hospital is listed as the sponsor. The study status is completed. The recorded start date is 2019-05-10, and the primary completion date is 2019-07-18. The registry lists enrollment of 80 participants.

The two groups received different capsule generations. In the first-generation group, participants swallowed the capsule with a small amount of water in the left lateral decubitus position. The description says the capsule was guided after examining the esophagus, including movement toward the fundus and cardiac regions. The registry’s description of this procedure is truncated, so it does not permit a complete account of every examination step. For the experimental group, the record says the process was the same except that the second-generation capsule was used.

Random allocation is intended to create groups that are comparable on average, while a parallel design assigns participants to one group for the comparison. Double masking indicates that the record classifies the trial as masked, but it does not identify which people were masked or explain how masking was maintained. Those details are not reported in the registry record.

The registry lists 40 participants at risk in each group for the posted adverse-event categories. It does not give a participant flow account, the number analyzed for the primary endpoint, or details of exclusions and withdrawals. The phase is listed as not applicable. A sample-size justification, allocation-generation method, concealment procedures, and a full statistical analysis plan are 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.

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 Circumferential Visualization of the Z-line, measured over Through end of examination, up to 30 minutes.

The primary endpoint is circumferential visualization of the Z-line, measured as a count of participants in categories describing the portion of the Z-line observed. The registry defines the categories as less than 2 quadrants (< 50%), at least 2 quadrants (50%-75%), at least 3 quadrants (>75%), and the entire Z-line (100%). The timeframe is through the end of examination, up to 30 minutes.

In general, a visualization endpoint can describe how completely an anatomical landmark was seen during an examination. Categorizing the observed extent may preserve clinically relevant distinctions that would be lost if the outcome were reduced to a simple yes-or-no measure. A participant count in each category could show whether the examination more often achieved broader visualization, while retaining information about incomplete visualization.

The categories in the registry definition are not accompanied by posted category counts or an inferential comparison. The wording also uses overlapping threshold descriptions at the boundary between some categories, so the record does not make the operational assignment rule fully clear. It is not appropriate to resolve that ambiguity by assuming a particular categorization scheme. Without the group-level endpoint results and the category-assignment details, the endpoint’s observed distribution and comparative precision cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does randomization contribute?

Randomization assigns participants to study groups using a chance-based process. In general, this can reduce systematic differences between groups at the time of assignment and supports a fair comparison of outcomes. It does not guarantee that every characteristic will be balanced, especially in a trial of limited size. The registry labels this study randomized but does not report how the sequence was generated, whether assignments were concealed before enrollment, or whether any departures from assigned groups occurred. Those implementation details are not reported in the registry record.

What does the parallel-group design mean?

In a parallel-group trial, each participant is assigned to one comparison group rather than receiving both study conditions in sequence. Here, the registry describes a first-generation MCCG group and a second-generation MCCG group. This design can compare outcomes between groups during the same study period, but interpreting the comparison still depends on knowing who was analyzed, what outcome data were observed, and how the analysis handled missing observations. The registry record does not report those details for the primary endpoint.

How should the categorical endpoint be understood?

The primary measure is a count of participants classified according to the extent of Z-line visualization. General statistical practice treats a categorical outcome by examining the distribution across its categories, rather than presuming that category labels are a continuous numerical scale. A comparison might use a method suited to categorical counts, but the appropriate method depends on the analysis plan and data structure. The registry does not report an analysis method for this endpoint or provide the counts needed to assess a distribution.

The stated category definitions include less than 2 quadrants (< 50%), at least 2 quadrants (50%-75%), at least 3 quadrants (>75%), and the entire Z-line (100%). The category wording is not fully explicit about how boundary observations are assigned, including how the categories relate to each other. The registry record does not clarify this. A statistical interpretation should therefore avoid silently converting the outcome to a simpler binary measure or assigning boundary values to a category by assumption.

What would an effect estimate and interval add?

In general, an effect estimate describes the contrast between groups on a defined outcome. A confidence interval conveys uncertainty around that estimate, conditional on the analysis and assumptions used. For a categorical endpoint, the choice of effect measure and interval should match the scientific question and the analysis method. Without group counts or an analysis result, no effect estimate or confidence interval can be reconstructed from the registry record. No new comparison can be calculated from the enrollment figure alone.

A p-value, in general, summarizes how compatible the observed data are with a specified null hypothesis under a statistical model. It is not the probability that the null hypothesis is true, and it does not indicate the clinical importance of a result. The registry does not report a p-value or the statistical test for the primary outcome. There is consequently no inferential result to interpret, and no basis for substituting an assumed test.

What does the sample-size illustration represent?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. It says the illustration varies the fraction of the observed effect to detect; for time-to-event outcomes, totals refer to events, while other outcomes are expressed as participants per arm. These are planning assumptions, not a description of the trial’s original design justification. The record does not report a sample-size justification for the trial itself. A planning illustration is not observed power and does not show that a completed study had adequate precision for its primary question.

Because no primary endpoint effect is reported in the registry record, this description cannot be used to claim that the observed effect was large, small, or statistically detectable. Any sample-size values associated with a planning exercise should be understood as hypothetical requirements under its stated assumptions, not as evidence about the trial’s outcome or about the probability that the trial detected an effect.

Why can category counts matter for precision?

General statistical reasoning: the information available for a categorical comparison depends on how observations are distributed across categories, not only on the number enrolled. Sparse categories can make some model-based approximations less reliable, while combining categories may discard distinctions and change the question being answered. A method should be chosen with the outcome definition and observed counts in view. Since the record does not report those counts or the analysis method, it is not possible to evaluate whether any particular approximation or modeling choice was appropriate.

What can be inferred from the registry’s method labels?

The design labels communicate that allocation was randomized, masking was double, and the study used parallel groups. They do not specify the primary analysis population, handling of missing outcome data, adjustment for covariates, or management of multiple outcomes. The record reports zero analyses. It therefore does not present an analysis result from which model assumptions, diagnostics, or robustness can be assessed. In general, these details are important because choices about inclusion, missingness, and analysis can affect both the estimated contrast and its uncertainty. They are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and multiple secondary outcomes, but it does not report a statistical plan for controlling or interpreting multiplicity. In general, testing several outcomes can increase the chance of observing at least one apparently notable result by chance if all tests are treated as independent opportunities for a finding. Different strategies can address that issue, including prespecifying a hierarchy or adjusting inference, but the registry record does not state that any particular strategy was used.

The primary endpoint itself has several categories. The record does not report whether the planned comparison was an overall test of the category distribution, an ordinal analysis, a contrast between selected categories, or another approach. It also does not report whether any categories were to be combined. The stated category wording leaves some boundary assignment details unclear.

Missing-data handling and the primary analysis population are not reported in the registry record. There is no participant flow account or endpoint-specific denominator. Without this information, it is not possible to determine whether all randomized participants contributed to the primary analysis, how missing examinations were treated, or whether any exclusions were made after allocation. The record also does not report interim analyses or a stopping rule. Those omissions should not be filled by assuming common trial practices.

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.

The adverse-event entries report zero serious events, zero other events, and zero deaths for the first-generation MCCG group and for the second-generation MCCG group. The record lists 40 participants at risk in each group for both serious and other adverse events. These are the registry’s recorded counts, not a complete account of every possible safety outcome or of how events were collected and classified.

In general, observing no recorded events does not establish that the underlying risk is zero. The interpretation of a zero count depends on the amount and duration of observation, event definitions, ascertainment procedures, and completeness of reporting. Those details are not reported in the registry record. The timeframe attached to the primary endpoint is not a substitute for a stated safety follow-up period.

The registry lists no top serious-event terms. That means no such terms appear in the record; it does not establish that every potential event was assessed in the same way or that unreported outcomes were absent. The adverse-event figures should therefore be read narrowly as the counts posted for the listed categories, without a broader safety conclusion.

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

The record shows that a randomized, double-blind, parallel-group comparison of second-generation and first-generation MCCG was completed, with enrollment of 80 participants. It identifies a primary endpoint based on the extent of Z-line visualization through the end of examination, up to 30 minutes. It also lists a set of secondary outcomes and posts adverse-event counts for each group.

Those details establish what the study set out to compare, but they do not reveal the comparative outcome. The registry does not report the distribution of participants across the primary endpoint categories, an effect estimate, an uncertainty interval, or a statistical test. It is therefore not possible to say whether visualization differed between groups, how large any difference was, or how precisely the study estimated it.

In general, a study design can make a comparison interpretable only when its outcome data and analysis are also available. Randomization helps frame a group comparison, but it does not supply missing results. Likewise, an outcome definition does not tell readers whether the endpoint was achieved more often in one group. The listed secondary outcomes also cannot be interpreted as findings without their results.

The posted safety counts show no recorded serious events, other events, or deaths in either group’s listed categories. They do not establish absence of risk, completeness of event ascertainment, or a safety advantage. The registry does not report the additional follow-up and collection details needed for broader interpretation.

Accordingly, the record supports a cautious account of design and reporting, rather than a conclusion about comparative effectiveness or safety. The missing outcome and analysis information is central: without it, the study’s main statistical question remains unanswered in the registry record.

13. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between a clearly stated research question and a reportable result. The registry identifies a randomized comparison and a primary endpoint, but does not provide the endpoint data or analysis. Readers can understand the intended comparison while recognizing that the central estimate and its uncertainty are unavailable.

The endpoint is categorical, with levels intended to describe increasing extent of Z-line visualization. Such outcomes require attention to the category definitions and the analysis target. A comparison of the full distribution answers a different question from a comparison that combines categories or focuses on a selected threshold. The registry’s boundary wording is not fully clarified, making transparent operational definitions particularly important.

The record also illustrates why outcome reporting should include more than a headline result. Group counts, analysis populations, missing-data handling, effect estimates, uncertainty intervals, and the statistical method would allow readers to assess both the magnitude and precision of the comparison. None of those primary endpoint analysis details is reported in the registry record.

Finally, the registry names a broad set of secondary outcomes alongside the primary measure. Without an account of the analysis plan, readers cannot tell how the study intended to interpret multiple outcomes or whether any multiplicity strategy was used. The trial is therefore statistically informative as an example of a defined device comparison whose posted record does not include enough results for the intended comparison to be evaluated.

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 for interpreting this trial is that the registry record does not report primary endpoint results. No category counts, group comparison, effect estimate, confidence interval, or p-value are available. The primary question therefore cannot be evaluated from the posted results.

The record reports enrollment but does not provide a participant flow account, endpoint-specific denominators, or the primary analysis population. Withdrawals, exclusions, missing examinations, and handling of missing endpoint data are not reported in the registry record. This prevents assessment of how completely the randomized groups contributed to the primary outcome.

The outcome definition gives category thresholds but does not fully clarify category assignment at boundaries or how overlapping wording should be resolved. The record does not report a statistical method for comparing categories. It also does not provide a protocol-level statistical plan, multiplicity approach, interim-analysis information, or sample-size justification. The stated planning assumptions do not establish the original design rationale.

Masking is identified as double, but the record does not identify who was masked or describe implementation. The first-generation procedure description is truncated, and the second-generation description is limited to the device substitution. These reporting gaps restrict assessment of procedural detail and potential sources of bias. They should be treated as omissions in the registry record, not grounds for assumptions about what occurred.

Finally, adverse-event entries are limited to the posted categories and counts. Safety observation duration and collection procedures are not reported. These gaps limit both outcome interpretation and assessment of how comprehensively safety was documented.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Second-Generation MCCG for Upper Gastrointestinal Tract. — NCT03977935.
• Registry record last updated 2020-10-27; status last verified 2019-06.
• Results first posted 2020-10-27.
• 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.

18. Record Summary

NCT03977935 is a completed randomized, double-blind, parallel-group trial sponsored by Changhai Hospital. The registry reports enrollment of 80 participants and compares second-generation with first-generation magnetically controlled capsule gastroscopy for the upper gastrointestinal tract.

The primary endpoint is circumferential visualization of the Z-line, recorded in categories through the end of examination, up to 30 minutes. Secondary outcomes include measures of detection, examination time, manipulation, image quality, lesions, transit, and cleansing. The record reports 40 participants at risk in each group for the posted adverse-event categories, with zero serious events, zero other events, and zero deaths in each.

Primary outcome counts and statistical comparisons are not reported in the registry record. The posted information therefore describes the trial’s design and measures but does not establish a comparative result.