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 Magnesium for Peroral Endoscopic Myotomy (NCT04638881), a randomized phase 2 study. The primary outcome is Esophageal Symptoms Questionnaire Score (ESQ).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04638881 |
| Phase | Phase 2 |
| Condition | Esophageal Spasm |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 92 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Stanford University |
| Results posted | Yes |
2. Clinical Question
Population
Participants undergoing peroral endoscopic myotomy in a trial focused on postoperative esophageal spasm-associated pain. The registry record lists esophageal spasm as the condition and records enrollment of 92 participants. Further eligibility details and the characteristics of the enrolled participants are not reported in the registry record.
Intervention
Magnesium sulfate given as a 50 mg/kg bolus at the start of mucosal incision, followed by a 25 mg/kg/hr infusion. The infusion was to stop at extubation.
Comparator
Normal saline 0.9%, given as a 50 mg/kg bolus at the start of mucosal incision, followed by a 25 mg/kg/hr infusion that was to stop at extubation. The registry describes the study as placebo-controlled.
Primary question
At 0 hours postoperatively, what esophageal symptoms questionnaire scores were observed in the magnesium sulfate and normal saline groups? The registry's hypothesis also refers to postoperative esophageal pain and perioperative opioid requirements, but the posted primary endpoint is the questionnaire score.
The clinical rationale recorded for the trial is that involuntary esophageal smooth muscle spasms can contribute to pain after peroral endoscopic myotomy, and that magnesium has antispasmodic properties. The trial tests whether the groups differ in the reported postoperative symptom score; the registry also lists opioid consumption and pain-related outcomes as secondary outcomes.
The primary endpoint is reported as a median and inter-quartile range for each group. Those summaries describe the observed score distributions, but they do not alone establish whether a group difference is statistically distinguishable from chance or how precisely the difference is estimated. An inferential comparison is not reported in the registry record.
3. Trial Design
This is a prospective, randomized, double-blind, placebo-controlled, parallel-group Phase 2 trial sponsored by Stanford University. The registry record lists the study as completed and reports enrollment of 92 participants. The magnesium sulfate group and the normal saline group each had 46 participants in the posted primary outcome results.
The assigned infusion began with a bolus at the start of mucosal incision, followed by a continuous infusion that was to end at extubation. The two groups had the same stated weight-based bolus and infusion schedule; the assigned substance differed. The registry describes double masking but does not report which people involved in the trial were masked or how masking was maintained.
The study start date is 2020-12-28, and the primary completion date is 2023-04-13. These dates describe the registry record and do not, by themselves, indicate when results were submitted or whether all planned analyses were completed. The registry lists the primary endpoint as the Esophageal Symptoms Questionnaire score at 0 hours postoperatively.
Four secondary outcomes are listed: the Esophageal Symptoms Questionnaire score, postoperative opioid consumption, postoperative day 1 opioid consumption, and an average visual acuity score pain score in the postanesthesia care unit. The record lists five outcome measures in total, but does not post an inferential analysis for the primary or secondary outcomes. Sample-size justification, the randomization procedure, allocation concealment, protocol deviations, and the detailed 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
| Stage | Magnesium Sulfate 50 mg/kg Bolus + 25 mg/kg/hr Infusion | Normal Saline 0.9% 50 mg/kg Bolus + 25 mg/kg/hr Infusion |
|---|---|---|
| STARTED | 46 | 46 |
| COMPLETED | 46 | 46 |
| NOT COMPLETED | 0 | 0 |
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 | Magnesium Sulfate 50 mg/kg Bolus + 25 mg/kg/hr Infusion | Normal Saline 0.9% 50 mg/kg Bolus + 25 mg/kg/hr Infusion | Total |
|---|---|---|---|---|
| Participants analysed | 46 | 46 | 92 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 27 | 27 | 54 |
| Age, Categorical: >=65 years | Participants | 19 | 19 | 38 |
| Age, Continuous | years | 59 (SD 18) | 58 (SD 18) | 58 (SD 18) |
| Sex: Female, Male: Female | Participants | 27 | 27 | 54 |
| Sex: Female, Male: Male | Participants | 19 | 19 | 38 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | participants | 46 | 46 | 92 |
| Body Mass Index (units: kg / m2) | kg/m^2 | 25.6 (SD 7.5) | 26.4 (SD 7.0) | 26.1 (SD 7.2) |
6. Primary Endpoint
The registry lists the primary outcome as Esophageal Symptoms Questionnaire Score (ESQ), measured over 0 hours postoperatively.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | score on a scale |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the Esophageal Symptoms Questionnaire score at 0 hours postoperatively. The registry describes the questionnaire as a validated survey addressing esophageal dysphagia, globus, and reflux. Participants answer 11 questions, each rated from 1 (Not severe) to 7 (Very severe); the responses are summed to produce a score ranging from 11 to 77, with higher scores indicating more severe dysphagia.
A symptom questionnaire is used to represent the participant-reported experience across several esophageal symptoms, rather than relying on a single symptom or an objective measurement. The registry identifies the score as the primary outcome, making it the main posted endpoint for interpreting the trial's stated question. The record does not report why this specific postoperative time was selected or how the endpoint was chosen over the listed secondary outcomes.
Scores are summarized by median and inter-quartile range. The magnesium sulfate group had a median of 24, with an inter-quartile range from 18 to 31. The normal saline group had a median of 35, with an inter-quartile range from 28 to 42. These summaries describe central tendency and the middle spread of observed scores; they do not provide an adjusted effect estimate or a confidence interval for the between-group comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary posted summaries show a median Esophageal Symptoms Questionnaire score of 24 in the magnesium sulfate group and 35 in the normal saline group at 0 hours postoperatively. The corresponding inter-quartile ranges are 18 to 31 and 28 to 42. Because higher scores indicate more severe dysphagia, the observed group medians are positioned differently on the scale, with the magnesium group having the lower median. This is a descriptive comparison, not a test of whether the groups differ beyond what could occur by chance.
The inter-quartile ranges give information about the middle half of observed scores in each group. They are not confidence intervals for the median, and they do not quantify uncertainty about the treatment contrast. The ranges overlap, but overlap or non-overlap of inter-quartile ranges is not, on its own, a statistical test. The registry record does not post a confidence interval, p-value, adjusted estimate, or other inferential result for the primary endpoint.
The registry lists randomized allocation and double masking, which are design features intended to support a fair comparison. However, the posted outcome summaries do not show whether the groups were balanced on participant characteristics, whether all participants contributed data at the endpoint, or whether the analysis accounted for any missing observations. Those details are not reported in the registry record.
The sponsor's stated hypothesis also mentions perioperative opioid requirements, but the primary posted outcome is the questionnaire score. Opioid consumption and other pain-related measures are listed as secondary outcomes; results for those outcomes are not reported in the registry record. Thus, the posted primary summaries cannot answer the separate opioid-consumption questions.
The record reports zero participants with serious adverse events in each group, as well as zero participants with other adverse events and zero deaths. These are descriptive safety counts. Their interpretation depends on how events were defined, when they were monitored, and how completely they were captured; those details are not reported in the registry record. A zero count in the posted record is not evidence that no event could occur.
Overall, the reported medians and inter-quartile ranges describe the participants' postoperative symptom scores by assigned group. They do not establish a statistically significant difference, demonstrate a causal effect, or show how the results would apply to people outside the trial. No sponsor inferential analysis is posted for the primary endpoint, and the registry record does not give enough information to reconstruct one.
9. Statistical Methods Explained
What does a median describe?
A median is the midpoint of the observed values after they are ordered. It is a measure of central tendency that is less influenced by unusually high or low observations than the arithmetic mean. Here, the posted medians describe the score distribution in each randomized group. The magnesium sulfate group median is 24, and the normal saline group median is 35. Each is a group summary; neither gives the score of every participant or the range of all individual scores.
The inter-quartile range describes the middle half of the observations, from the first quartile to the third quartile. The registry reports 18 to 31 for the magnesium sulfate group and 28 to 42 for the normal saline group. It is a spread summary, not a measure of precision around the median or the treatment contrast. Readers should distinguish observed variability among participants from uncertainty about an estimated group difference.
What would an inferential comparison add?
An inferential analysis would estimate how compatible the observed group contrast is with random variation under a stated statistical model. A confidence interval would give a range of values compatible with the data and model at a specified confidence level; it would convey uncertainty about the effect estimate, rather than the spread of individual scores. A p-value would describe how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the analysis assumptions. Neither measure is reported for the primary endpoint in the registry record.
Because the endpoint is summarized with medians and inter-quartile ranges, a reader should not infer that the analysis necessarily used a particular test. The statistical test, model, covariate adjustment, and handling of ties or distributional features are not reported in the registry record. The posted descriptive summaries alone are insufficient to reconstruct a sponsor analysis.
Why does randomization matter?
Random assignment aims to make the treatment groups comparable, on average, with respect to factors that could influence the outcome. It supports interpreting an appropriately conducted between-group analysis as a comparison of assigned strategies rather than a simple comparison of self-selected treatments. Randomization does not guarantee that every measured or unmeasured characteristic will be balanced in a particular trial, especially when group sizes are limited. Baseline characteristics and the randomization method are not reported in the registry record.
Double masking is intended to reduce the risk that knowledge of assigned treatment influences care, outcome assessment, or participant reporting. Because this endpoint is a symptom questionnaire, expectations and assessment procedures can matter. The registry states that the study was double-blind but does not identify who was masked or describe whether masking was assessed.
How should the sample-size illustrations be read?
Planning calculations based on an observed effect are hypothetical illustrations, not trial results and not evidence that the trial had adequate power. Such calculations depend on assumptions, including the target effect, allocation, significance level, and statistical approximation. A planning illustration based on the observed effect is especially dependent on the size of the effect seen in this particular sample; it does not establish that an effect of that size is true or reproducible. The trial's own sample-size justification is not reported in the registry record.
Power is a design-stage probability of detecting a specified effect under stated assumptions if that effect is present. It is not a measure of the probability that the observed result is true. A retrospective calculation using the observed effect should not be described as observed power. The registry record provides no sponsor analysis from which to assess the precision of the primary comparison.
What cannot be inferred from the posted summaries?
The primary results are group-level summaries. They do not show individual score values, score distributions in full, or the relationship between symptoms and other outcomes. The registry does not post the number of participants with endpoint data separately from the group sizes shown, nor does it explain how missing outcome data were handled. The analysis population and any exclusions are not reported in the registry record.
For these reasons, the posted results support a descriptive account of the endpoint and group summaries, but not a claim about statistical significance or an adjusted causal estimate. Any more specific inference would require the analysis methods and data that are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary questionnaire endpoint and four secondary outcomes. When a study evaluates multiple outcomes, the chance of at least one apparently notable result can increase if each is tested without accounting for the set of comparisons. Statistical plans may address this through a prespecified hierarchy, adjustment procedure, or other strategy. The registry record does not report whether any multiplicity strategy was planned or used. No inferential analyses are posted for the listed outcomes.
The registry identifies the primary endpoint and its postoperative time, but does not report a detailed statistical analysis plan, secondary endpoint timing beyond the named measures, or a testing hierarchy. It is therefore not possible to tell from the posted record whether the primary outcome was the sole confirmatory test, how secondary findings were intended to be interpreted, or whether any analyses were exploratory.
Missing data can affect both the estimated group summaries and the validity of a comparison, particularly if the likelihood or reasons for missingness differ between groups. The registry lists 46 participants in each group for the primary outcome, but does not report the number with observed endpoint data, any missing-data counts, reasons for missingness, or imputation methods. An analysis population, such as all randomized participants or only those with available measurements, is not reported in the registry record.
The record does not describe interim analyses, stopping rules, protocol deviations, or adjustments for them. These details are not reported in the registry record; their absence from the posted information should not be treated as evidence that a particular procedure was or was not used. Without these details, the descriptive endpoint summaries can be read as posted, but their inferential context remains limited.
11. 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 |
|---|---|---|---|
| Magnesium Sulfate 50 mg/kg Bolus + 25 mg/kg/hr Infusion | 0 | 46 | 0.0% |
| Normal Saline 0.9% 50 mg/kg Bolus + 25 mg/kg/hr Infusion | 0 | 46 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Magnesium Sulfate 50 mg/kg Bolus + 25 mg/kg/hr Infusion | 0 of 46 |
| Normal Saline 0.9% 50 mg/kg Bolus + 25 mg/kg/hr Infusion | 0 of 46 |
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 |
|---|---|
| Magnesium Sulfate 50 mg/kg Bolus + 25 mg/kg/hr Infusion | 0 of 46 |
| Normal Saline 0.9% 50 mg/kg Bolus + 25 mg/kg/hr Infusion | 0 of 46 |
The registry reports that, among 46 participants at risk in the magnesium sulfate group, zero had a serious adverse event, zero had another adverse event, and zero deaths were recorded. For the normal saline group, 46 participants were at risk; the corresponding counts were also zero, zero, and zero. These figures describe the event counts in the registry record, not a comparison demonstrating equal safety.
A zero count means no event in that category was recorded among the stated group at risk in the posted results. It does not show that the risk is absent, and it does not exclude events that were not captured or reported. Safety interpretation also depends on the event definitions, surveillance period, and completeness of reporting. The registry record does not report those details or list serious adverse event terms.
The record therefore supports a narrow description of the posted counts. It does not allow a precise estimate of event risk, a formal between-group safety comparison, or a conclusion about rare or later events. The reported death count is zero in both groups; no further details about cause or follow-up are reported in the registry record.
12. What the Result Does, and Does Not, Mean
The primary outcome results describe postoperative questionnaire scores in the randomized groups. The magnesium sulfate group had a median score of 24, with an inter-quartile range of 18 to 31; the normal saline group had a median score of 35, with an inter-quartile range of 28 to 42. Since higher scores indicate more severe dysphagia, the observed group summaries place the magnesium group's median lower on the score scale. This is the scope of what the posted primary endpoint directly shows.
The summaries do not establish that the observed difference is statistically significant, clinically important, or caused by the assigned infusion. The registry record does not report an inferential analysis, confidence interval, p-value, or criteria for interpreting a meaningful score difference. It also does not provide a minimally important difference for the questionnaire in this trial.
The primary endpoint measures reported esophageal symptoms at 0 hours postoperatively. It does not by itself answer whether opioid consumption differed, whether symptoms persisted, or whether there were differences in other postoperative outcomes. Although those measures appear among the secondary outcomes, their results are not reported in the registry record.
The trial is randomized and double-blind according to the record, but interpretation also depends on details not posted, including participant characteristics, missing observations, outcome ascertainment, and the prespecified analysis. Likewise, the safety counts of zero in both groups are limited to the events recorded and do not establish the absence of risk.
Accordingly, these results are best read as descriptive evidence from the enrolled participants, rather than a definitive conclusion about treatment effects or safety. The record does not report enough analysis detail to determine the precision or robustness of a between-group effect estimate.
13. Why This Trial Matters Statistically
This trial is statistically interesting because it places a participant-reported symptom outcome at the center of a randomized, double-blind comparison. Such outcomes capture experiences that may not be represented by physiological measures alone, but their interpretation depends on a clear scoring rule, consistent administration, and attention to measurement variability. The registry describes the questionnaire content, response scale, score range, and direction of interpretation, which makes the reported medians easier to understand.
The endpoint is reported with a median and inter-quartile range rather than a mean and standard deviation. That choice conveys a central summary and the spread of the middle half of observed scores. It also underscores an important distinction for clinical researchers: descriptive distribution summaries are not substitutes for an effect estimate with uncertainty. The record's lack of a posted inferential analysis limits what can be concluded from the group comparison.
Randomization and masking are relevant design features for a symptom outcome, since assignment and expectations may influence participant reporting or outcome assessment. Yet registry descriptions of those features do not remove the need for transparent reporting of allocation methods, analysis populations, missing data, and prespecified comparisons. Those details are not reported in the registry record.
The study also illustrates why the primary outcome must be kept distinct from the broader hypothesis. Opioid consumption and additional pain-related measures are listed as secondary outcomes, while the posted primary result concerns the questionnaire at a specified postoperative time. Separate outcome results and analyses are needed to answer each question. The posted record therefore offers a clear endpoint definition and descriptive group summaries, while leaving key inferential and reporting questions unresolved.
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 most important limitation in interpreting this trial record is that it posts descriptive primary outcome summaries without a statistical comparison. There is no reported confidence interval, p-value, adjusted estimate, or analysis method for the primary endpoint. The observed medians can be described, but the precision and inferential strength of a between-group contrast cannot be assessed from the registry record.
The record does not report baseline participant characteristics, eligibility criteria, the randomization sequence method, allocation concealment, or the people included in double masking. It also does not report whether all randomized participants contributed to the primary endpoint, the number of missing scores, reasons for missingness, or how missing data were handled. These gaps limit assessment of comparability and potential bias.
Although four secondary outcomes are listed, their results are not reported in the registry record. The record also does not describe a multiplicity plan, a detailed statistical analysis plan, interim analyses, or protocol deviations. Consequently, it is unclear how the outcome set was intended to support confirmatory or exploratory conclusions.
The safety results are limited to zero recorded serious adverse events, zero other adverse events, and zero deaths in each group. Event definitions, surveillance duration, and completeness of reporting are not described. The record's adverse-event counts should therefore be interpreted narrowly, rather than as a complete characterization of safety.
Finally, the posted primary endpoint is a questionnaire score at 0 hours postoperatively. Results at later times and details about the clinical interpretation of score differences are not reported in the registry record. The extent to which these findings apply beyond the enrolled study population cannot be assessed without participant and setting details.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Magnesium for Peroral Endoscopic Myotomy — NCT04638881.
- Registry record last updated 2024-05-21; status last verified 2024-04.
- Results first posted 2024-05-21.
- 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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18. Record Summary
The registry record describes a completed, prospective, randomized, double-blind, placebo-controlled, parallel-group Phase 2 trial sponsored by Stanford University. It lists enrollment of 92 participants and compares magnesium sulfate with normal saline during peroral endoscopic myotomy. Each group had 46 participants in the posted primary outcome results.
The primary endpoint is the Esophageal Symptoms Questionnaire score at 0 hours postoperatively. The magnesium sulfate group had a median score of 24 and an inter-quartile range of 18 to 31; the normal saline group had a median of 35 and an inter-quartile range of 28 to 42. No inferential analysis for this endpoint is reported in the registry record.
Four secondary outcomes are listed, but their results are not reported in the registry record. The posted adverse-event counts are zero serious adverse events, zero other adverse events, and zero deaths in each group. Details of missing data, analysis populations, and the statistical analysis plan are not reported in the registry record.