Detachable String Magnetically Controlled Capsule Endoscopy for Completely Viewing of Esophagus and Stomach: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Detachable String Magnetically Controlled Capsule Endoscopy for Completely Viewing of Esophagus and Stomach (NCT03457909), a na na study. The primary outcome is Number of Participants With Successful Separation of Capsule and String, and Complete Viewing of Esophagus and Stomach.

2. Clinical Question

The clinical question is about procedural feasibility rather than a comparison of treatment effects. The primary endpoint combines two procedural conditions: the capsule enters the stomach while the string is pulled out, and the examination proceeds through swallowing the capsule, retrograde observation of the esophagus, and string withdrawal after separation from the capsule. The registry describes the endpoint as the number of participants completing the DS-MCE examination successfully.

This outcome can indicate whether the specified procedure was completed under the study conditions. It does not, by itself, establish how accurately the examination identifies disease, whether it changes clinical decisions, or whether it performs better than conventional endoscopy. Those questions would require outcomes and comparative analyses not reported in the registry record. The record also lists secondary outcomes concerning adverse events, time in the esophagus, Z-line visualization and image quality, and comfort, but their results are not reported in the registry record.

3. Trial Design

The registry describes a completed study of DS-MCE with an enrollment of 25. It identifies the model as single group and gives allocation as NA and masking as none. No randomized allocation or separate control arm is described. The arm description says that outpatients who have esophagus symptoms take DS-MCE and conventional endoscopy examination successively. This sequence does not make the study a randomized comparison: the record does not describe assignment to alternative groups or a like-for-like control comparison.

The study's stated purpose was to assess the safety and feasibility of DS-MCE for evaluating gastric and esophagus diseases. The named intervention is a device, DS-MCE. The primary outcome is a participant count for successful separation of capsule and string together with complete viewing of the esophagus and stomach. Its timeframe is up to 2 weeks. Secondary outcomes listed in the record include DS-MCE-associated adverse events, duration of time the capsule is within the esophagus, Z-line visualization, quality score of Z-line images, and degree of comfort.

The record gives a start date of 2018-03-07, a primary completion date of 2018-07-10, and a status of completed. Changhai Hospital is listed as sponsor. The phase field is NA, which is not a reported phase designation. The registry record does not report a detailed protocol, the sequence or conditions of all assessments beyond the successive examinations in the arm description, or a statistical analysis plan. It also does not report a rationale for the enrollment target.

Because the study has a single group and no described randomized comparator, its primary endpoint is best read as a feasibility count from participants undergoing the procedure. A count from this design does not estimate a between-group treatment effect. The record lists no analysis entries, and it does not report the primary outcome result. Consequently, the design can be described from the registry fields, but the magnitude and precision of the observed feasibility result cannot be assessed from this 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.

Before assignment: This study was a prospective, self-controlled, single-centered pilot study. After enrollment, each enrolled subject first underwent DS-MCE(detachable string magnetically controlled capsule endoscopy), and subsequently EGD(esophagogastroduodenoscopy) within one week.

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 Number of Participants With Successful Separation of Capsule and String, and Complete Viewing of Esophagus and Stomach, measured over up to 2 weeks.

The primary endpoint is the number of participants with successful separation of the capsule and string and complete viewing of the esophagus and stomach. The registry defines separation as the capsule entering the stomach while the string is pulled out. Complete viewing is described as completing the procedure from swallowing the capsule, to observing the esophagus retrograde, to pulling out the string after it separates from the capsule. The stated timeframe is up to 2 weeks.

This endpoint is used to address a practical feasibility question: whether participants complete the intended examination process. A participant count is a natural way to express how many people met the specified procedural definition. For interpretation, the definition matters: the endpoint combines capsule-string separation with completion of viewing, rather than reporting either procedural component as a separate primary outcome.

The registry record does not report the observed number of participants meeting this definition. It also does not state a separate rule for handling an incomplete examination, missing assessment, or ambiguous procedural result. Without the observed count and its analysis details, the endpoint's result and its precision cannot be judged. Even when reported, successful completion would address feasibility under the study conditions, not diagnostic accuracy or comparative performance unless those are evaluated separately.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a single-group study and lists no analysis entries. It does not report the statistical methods used to analyze the primary endpoint, the secondary outcomes, or safety data. The explanations below describe general statistical concepts relevant to the stated outcomes; they should not be read as a description of an analysis confirmed by the registry record.

What does a participant count convey?

For a binary procedural endpoint, each participant is classified according to whether the defined success condition was met. A count tells how many participants had the event of interest, but a count alone does not express the uncertainty around the underlying probability of success. A proportion and a confidence interval can help communicate that uncertainty, provided the numerator, denominator, and analysis are reported. The primary result needed for such an interpretation is not reported in the registry record. No success proportion or interval should therefore be inferred from the enrollment figure alone.

A confidence interval is a range of values compatible with the observed data under a specified statistical method. It communicates precision, not certainty that the true value lies within that particular calculated range. When the number of observations is limited or outcomes are uncommon, intervals may be wide, and the choice of method can matter. The registry record does not report an interval or the method used to calculate one for this endpoint.

Why does the endpoint definition matter?

The primary endpoint joins successful separation of the capsule and string with complete viewing of the esophagus and stomach. A participant must meet the defined procedural conditions to count as a successful completion. This makes the endpoint clinically interpretable as a complete-procedure measure, but it does not reveal which component caused failure if the composite condition is not met. Separate component counts could clarify whether difficulties occurred during separation, visualization, or another part of the procedure, but those results are not reported in the registry record.

The outcome's timeframe is up to 2 weeks. A timeframe indicates the window within which an outcome is assessed; it does not, on its own, explain exactly when or how each participant was evaluated. Detailed assessment timing, rules for incomplete examinations, and handling of missing outcome data are not reported in the registry record.

What can a single-group design establish?

A single-group result describes what was observed among participants who underwent the procedure. It does not, by itself, estimate what would have happened to comparable participants under an alternative procedure. A causal comparison generally needs a valid comparator and a design and analysis that address differences between groups. Here, conventional endoscopy is described as an examination performed successively, not as a separately randomized control group. The registry record does not describe a comparative analysis. Any claim about relative performance would therefore go beyond the design information recorded.

Successive examinations can raise questions about order, timing, and whether the findings or experience from one examination influence the other. The registry record does not provide enough detail to determine how such issues were handled, and no comparative results are reported. These are design considerations, not evidence that a particular bias occurred.

How should safety counts be interpreted?

Adverse-event counts describe events recorded under the study's reporting process. A count of zero means that no affected participants are entered for that category in the registry data; it does not prove that an event is impossible or that all events would necessarily have been detected. Interpretation also depends on the definitions, observation period, completeness of follow-up, and event-collection procedures. Those details are not reported in the registry record. Counts should not be converted into broader safety conclusions without this context.

For rare or serious events, absence of an observed event can coexist with uncertainty about the underlying risk. A confidence interval can express uncertainty around an event rate when the relevant count and denominator are available, but no interval or event-rate analysis is reported. No additional safety estimate should be inferred.

What does a planning illustration mean?

A sample-size planning illustration is a hypothetical calculation for designing a future study. The assumptions recorded for the illustration are 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. These are planning assumptions, not a report of the trial's actual design, because the study is recorded as single group and allocation is NA. A planning calculation is not observed power and does not show that the study detected an effect. The registry record does not provide a sample-size justification for this study.

In general, a planning calculation depends on the outcome, the target effect, the chosen error rate, the allocation structure, and the statistical method. Changing those assumptions changes the required sample size. If a planning illustration is based on an observed effect, it is conditional on that effect estimate and should not be treated as independent confirmation of the finding. No additional calculation or trial-specific sample-size conclusion is available from the registry record.

What can be concluded from the analysis record?

The record lists no analysis entries. It does not identify an analysis population, a missing-data method, an adjustment strategy, or a method for secondary-outcome testing. General methods such as exact procedures for binary data, regression adjustment, or correction for multiple testing cannot be attributed to this study without documentation. The safest statistical reading is to separate what the registry describes—the endpoint definition, design, and entered safety counts—from the analyses and results that it does not report.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("DS-MCE")
n      <- c(25)
events <- c(25)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  DS-MCE  25  25  100.0  86.3  100.0  86.7  100.0  86.8  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists secondary outcomes covering DS-MCE-associated adverse events, time the capsule is within the esophagus, Z-line visualization, Z-line image quality, and degree of comfort. It reports 6 outcome measures, but the registry record does not provide results for the listed secondary outcomes. It also does not identify a hierarchy of outcomes, a prespecified testing order, or a method for addressing multiple statistical tests. These details are not reported in the registry record.

Multiplicity is a general statistical concern when several outcomes or comparisons are tested: the more questions are examined, the greater the chance that at least one result appears notable by chance if each is interpreted without regard to the others. A prespecified primary endpoint can focus interpretation, while a stated testing strategy can clarify how secondary findings are to be treated. The record names a primary endpoint but does not report a multiplicity strategy. This does not establish that no such strategy existed; it means the registry record does not report one.

The registry record does not explain how missing or unevaluable outcome data were handled. It does not report an analysis population, exclusions from analysis, imputation, or sensitivity analyses. For a procedural endpoint, incomplete examinations and unavailable assessments can affect how a participant is classified; the record does not state the rules applied. The enrollment figure alone cannot establish the denominator used for any outcome analysis.

These omissions limit assessment of whether the analysis followed a prespecified plan and how robust the reported results would be to missingness or multiple testing. Since no analysis entries or primary outcome result are reported, the record does not support a reconstructed analysis or a judgment about the impact of missing data.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The DS-MCE safety record lists 0 serious adverse events among 25 participants at risk and 0 other adverse events among 25 participants at risk. The death count is 0. These are the registry's entered counts for the study group; they should be read as reported event data, not as proof that the procedure has no risk.

A zero count can mean that no events in a category were recorded in the registry data. It does not establish that every possible event was captured or that the chance of an event is zero. Interpretation depends on how events were defined, whether they were actively monitored, how long participants were followed, and how completely events were recorded. The registry record does not report these details or list serious adverse-event terms.

The safety figures are not a comparison with a control group. The study is recorded as single group, and conventional endoscopy is described as a successive examination rather than a randomized control arm. The counts therefore do not estimate a comparative safety effect. The record also does not report an uncertainty interval or a detailed safety analysis. The most precise reading is limited to the counts entered in the registry and the absence of further safety details in the registry record.

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

This record documents a study designed to assess the feasibility and safety of DS-MCE for viewing the esophagus and stomach. Its primary endpoint has a concrete procedural definition: successful separation of the capsule and string together with complete viewing of both organs. The record also lists outcomes for adverse events, time in the esophagus, Z-line visualization and image quality, and comfort. These details clarify what the study intended to examine.

The record does not report the observed primary endpoint count. It therefore does not establish how many participants completed the procedure successfully, how precise that result was, or whether the endpoint met any prespecified threshold. The missing result cannot be interpreted as either successful completion by everyone or failure by everyone. The posted safety counts show no serious or other adverse events entered for the group, but they do not prove an absence of risk.

The study's single-group design also limits what can be inferred. Although conventional endoscopy is described as occurring successively, the registry does not describe a randomized comparison or a like-for-like control group. The record consequently does not provide a comparative estimate of feasibility, safety, diagnostic accuracy, or patient experience. It does not report a result showing whether DS-MCE identifies disease accurately or performs better or worse than another examination.

In general, feasibility findings can support understanding of whether a procedure can be carried out under the conditions studied. They do not automatically establish diagnostic value, effects on clinical decisions, or broader applicability. Those conclusions require relevant outcomes, adequately described methods, and reported analyses. The registry record does not provide those results or details. Its contribution is therefore a description of the research question and recorded design, accompanied by limited safety counts, while the main feasibility outcome remains unavailable in the record.

14. Why This Trial Matters Statistically

This study raises a clear statistical distinction between a feasibility question and a comparative-effectiveness question. Counting participants who complete a defined procedure can describe whether the process was accomplished in the study group. It cannot, without a suitable comparison, determine whether one examination performs better than another. The record's description of successive examinations should not be mistaken for randomized allocation or a controlled comparison.

The endpoint also illustrates why operational definitions are important. Successful completion is not simply a general impression that the examination worked: the record specifies capsule entry into the stomach, string withdrawal after separation, and complete viewing through the described procedure. That definition makes the target outcome more concrete. At the same time, because the primary measure combines these procedural elements, separate component results would be needed to explain which part of the process contributed to an incomplete examination.

Statistical precision is as important as the observed count. A feasibility count is most informative when accompanied by its analysis denominator and an uncertainty interval. The primary result and its precision are not reported in the registry record, so readers cannot assess how much uncertainty surrounds the intended feasibility estimate. The enrollment figure alone does not supply the missing endpoint count.

The safety figures offer another useful lesson: zero recorded events are data, but they are not proof of zero risk. Their interpretation depends on event definitions, surveillance, follow-up, and reporting completeness, details not reported in the registry record. Clear reporting of these elements is particularly important when a study is intended to assess safety and feasibility.

Finally, the listed secondary outcomes point to several distinct aspects of the examination, but their results and the approach to multiple testing are not reported. Separating a prespecified primary question from exploratory secondary questions helps readers judge how strongly each finding should be interpreted. Here, the registry record leaves both the main result and the statistical analysis details unavailable, making transparent reporting central to any further interpretation.

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 most consequential limitation for interpreting the posted record is that the primary outcome result is not reported. Although the endpoint and timeframe are described, the registry does not state the number of participants who achieved successful capsule-string separation and complete viewing. Without that result, feasibility cannot be quantified and precision cannot be assessed.

The design is recorded as single group, with allocation NA and no masking. The arm description reports successive DS-MCE and conventional endoscopy examinations, but the registry does not describe a randomized control group or a comparative analysis. The record therefore cannot support conclusions about relative performance. It also does not give enough detail to assess the implications of examination order or the relationship between the successive assessments.

The registry does not report detailed eligibility criteria, a fuller account of the enrolled population, procedural training or operator experience, or the rules used to classify incomplete examinations. Generalizability beyond the described outpatient setting and participants with esophagus symptoms cannot be judged from the available information. The record does not report diagnostic accuracy findings or results for the secondary outcomes.

Statistical limitations include no analysis entries, no reported analysis population, no missing-data method, and no described multiplicity strategy. A sample-size justification is not reported in the registry record. The safety figures include zero serious and zero other adverse events entered, but event definitions, collection procedures, follow-up detail, and uncertainty estimates are not reported. These gaps do not prove that the study lacked methods or procedures; they limit what can be assessed from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Detachable String Magnetically Controlled Capsule Endoscopy for Completely Viewing of Esophagus and Stomach — NCT03457909.
• Registry record last updated 2019-09-23; status last verified 2019-08.
• Results first posted 2019-09-23.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT03457909 is a completed, single-group study sponsored by Changhai Hospital, with an enrollment of 25. It evaluated detachable string magnetically controlled capsule endoscopy in outpatients with esophagus symptoms. The arm description states that participants underwent DS-MCE and conventional endoscopy successively. The primary endpoint was the number of participants with successful capsule-string separation and complete viewing of the esophagus and stomach, assessed within up to 2 weeks.

The registry record does not report the primary outcome result or results for the listed secondary outcomes. It lists 0 serious adverse events and 0 other adverse events among 25 participants at risk, with 0 deaths. No analysis entries are listed. The record does not describe a randomized comparison, a detailed statistical analysis plan, or methods for missing data and multiplicity. The design and posted safety counts can be described, but the primary feasibility result and its precision cannot be assessed from the registry record.