Temporary Gastric Electrical Stimulation for Drug Refractory Gastroparesis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Temporary Gastric Electrical Stimulation for Drug Refractory Gastroparesis (NCT00432835), a randomized phase 3 study. The primary outcome is Symptom of Vomiting Associated With Gastroparesis.

2. Clinical Question

This is a question about a symptom score, not a direct measure of stomach emptying. The primary outcome is described as a mean on a patient-reported Likert scale, with higher values representing more severe symptoms. The crossover arrangement means that participants were assigned to different sequences of active and sham stimulation, rather than each group remaining in only one condition throughout. That design can support within-participant comparisons, but interpretation depends on the recorded outcome values, the analysis of the repeated observations, and how the crossover periods were handled. Those details and the primary comparison are not reported in the registry record.

3. Trial Design

The registry record describes a completed Phase 3 study with randomized allocation, quadruple masking, and a crossover model. Enrollment was 58. The sponsor was University of Mississippi Medical Center. The record lists the study start as 2005-08 and primary completion as 2006-10.

The intervention was a gastric electrical stimulator, named in the record as Gastric Electrical Stimulator, Enterra, Medtronics, Inc. The two arm descriptions indicate different sequences of active stimulation and sham or no stimulation. One sequence is described as active stimulation for 72 consecutive hours followed by a 1 day wash out and crossover. The other is described as no stimulation until Day 5, followed by crossover to active stimulation. The descriptions are truncated, so the complete sequence and all procedural details are not reported in the registry record.

In a crossover trial, participants receive more than one study condition in sequence. General explanation: each participant can therefore contribute observations under both conditions, which may make comparisons less dependent on differences between participants. The design also makes period effects and possible carryover relevant: symptoms may change over time for reasons other than the assigned condition, and effects from an earlier period may persist into a later one. A washout is intended to separate periods, but its adequacy cannot be assessed from the registry record alone.

The record does not report the sequence-generation method, allocation concealment procedures, the identities of the masked roles, or a full protocol. It also does not report the planned sample-size justification or a detailed statistical analysis plan. The enrollment figure describes the study overall; it does not establish how many participants contributed usable outcome data to each period or analysis.

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: No significant events or approaches for the overall study following participant enrollment were performed prior to group assignment.

Overall Study

Reasons for not completing this period:

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 Symptom of Vomiting Associated With Gastroparesis, measured over Study Day 0 (Baseline), Day 3, Day 7.

The primary endpoint is titled “Symptom of Vomiting Associated With Gastroparesis.” It is a patient self-reported symptom score measured with a patient-reported outcomes tool, on a Likert Scale 0-4, with 0 described as low and 4 as high. The listed time points are Study Day 0 (Baseline), Day 3, and Day 7. The endpoint is summarized as a mean, with standard error as the stated measure of dispersion.

A symptom score captures a patient’s report of how troublesome a symptom is, rather than measuring a physiological process directly. Vomiting is relevant to the stated study question because the trial concerns symptoms associated with gastroparesis and the record identifies this score as its primary outcome. Repeated measurements can describe how scores change over the study periods. In a crossover design, comparisons across active and sham periods are most informative when the analysis accounts for the within-participant structure and the sequence of exposure.

General explanation: the mean describes the average score in a group, while the standard error describes the precision of an estimated mean. Neither alone gives the spread of individual participants’ experiences. The registry record does not report the observed means, standard errors, a treatment contrast, or a confidence interval for the primary endpoint. It therefore does not establish the size or precision of any difference in vomiting scores.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the study as randomized, quadruple masked, and crossover. These terms describe separate features of a trial. Randomization assigns participants to a study sequence by chance. Masking aims to limit the influence of knowledge about assigned condition on participants, study personnel, or outcome assessment. The record does not specify which four roles were masked or the practical procedures used to preserve masking. Crossover means that participants are assigned to sequences in which the study conditions occur at different times, rather than being assigned to only one condition for the entire study.

Why does a crossover design change the comparison?

General explanation: when the same participant contributes measurements under more than one condition, an analysis can compare that participant with themself. Stable differences between participants may then contribute less to the condition comparison than they would in a parallel-group design. This benefit relies on suitable outcome data from the relevant periods and an analysis that respects the repeated measurements. The registry record does not report the primary analysis method or the number of participants with complete paired data.

Time and sequence matter in crossover trials. A period effect is a change associated with when a measurement is taken, rather than with the condition itself. A carryover effect occurs when exposure in an earlier period continues to influence outcomes in a later period. The arm descriptions mention a wash out, but the registry record does not provide a complete protocol or report how period, sequence, or carryover were assessed or handled. No conclusion about those design issues can be drawn from the listed schedule alone.

What does the endpoint summary describe?

The primary outcome is a continuous patient-reported score summarized as a mean, with standard error. Its scale is described as a Likert Scale 0-4, low to high, for vomiting symptoms. General explanation: a mean summarizes the average observed score, while the standard error reflects the precision of that estimated mean under the statistical model. A standard error is not the same as the spread of scores among individual participants. To interpret a condition contrast, readers would also need the estimated difference, its uncertainty, and a clear account of which observations and participants entered the analysis. Those results are not reported in the registry record.

The listed time points are Study Day 0 (Baseline), Day 3, and Day 7. A baseline measurement can describe starting symptom scores, while later measurements can describe scores during the study. For a randomized crossover comparison, however, a change from baseline alone is not necessarily the same as a contrast between active and sham conditions. The record does not state how the time points were mapped to the treatment periods in the primary analysis or how the treatment contrast was defined.

How should precision and significance be understood?

General explanation: an effect estimate describes the size and direction of a comparison. A confidence interval expresses uncertainty around that estimate under the chosen model and assumptions. A p-value is a measure of how compatible the observed data are with a specified null hypothesis, also conditional on the analysis assumptions. These quantities answer related but different questions; statistical significance does not by itself describe the magnitude or practical importance of an effect. The registry record does not report a primary effect estimate, confidence interval, or p-value, so these concepts cannot be applied to a numerical primary result.

Over-dispersion is relevant in general when count data vary more than a model assumes; it can make standard errors too small if the extra variation is ignored. The primary endpoint in this trial is described as a continuous mean score, not a count outcome. No model or dispersion assessment is reported, so it would be inappropriate to claim that over-dispersion was present or that a particular model was used.

What can planning illustrations establish?

General explanation: a sample-size calculation can show how many participants per arm might be needed under stated assumptions about the target effect, significance level, allocation, and model. The planning assumptions recorded for this trial describe an illustration based on the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They also describe evaluating specified fractions of the observed effect. The registry record does not report the trial’s own sample-size justification, and no planning illustration should be read as observed power or as proof that a comparison was adequately powered.

For a crossover design, a planning calculation also depends on the analysis and on how measurements within a participant relate to one another. The assumptions in the record describe a two-arm illustration, but do not establish the original design calculation or its suitability for the crossover structure. No additional sample-size assumptions should be inferred.

Finally, the registry lists no analyses and does not provide an analysis plan. It is not reported whether the primary analysis was prespecified in a protocol, how multiple time points or outcomes were handled, or whether any adjusted analyses were planned. Accordingly, the design terms and endpoint description explain what was intended, but not how the primary comparison was ultimately estimated.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome lists measurements at Study Day 0 (Baseline), Day 3, and Day 7, and the registry lists 3 outcome measures overall. Considering multiple outcomes or time points can create multiplicity: when several hypotheses are tested, the chance of at least one apparently notable result can increase. General explanation: statistical plans often specify which comparison is primary and whether adjustments or a hierarchy are used. The registry record does not report a multiplicity strategy, the planned contrasts, or a detailed statistical analysis plan. It is therefore not possible to determine which comparisons were intended to be confirmatory or how multiple testing was addressed.

The record lists 0 analyses. It does not report the methods used to handle missing outcome measurements, the number of missing observations, or whether the analysis followed an intention-to-treat, per-protocol, or other population definition. It also does not report participant flow through the crossover periods or how incomplete sequences were handled. These omissions matter because a crossover comparison may depend on having observations from both conditions, and missingness can affect both the amount of information and the interpretation of a comparison.

The registry record does not report whether any imputation, sensitivity analysis, or missing-data model was used. The 58 enrolled participants should not be assumed to be the number analyzed for every endpoint. The safety denominators do not establish the primary-outcome analysis population. Without these details, the robustness of any unreported primary estimate to missing data or alternative analysis populations cannot be assessed.

11. Safety Results

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

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 adverse-event record lists 0 serious adverse events among 51 participants at risk in the “Gastric Stimactivated” group and 0 among 52 participants at risk in the “Gastric StimulationNotActivated” group. These are the registry’s reported serious adverse event counts and denominators. They are not the primary symptom outcome, and they do not by themselves establish a comparison of overall safety between conditions.

The record also lists other adverse events for 6 of 51 participants in the activated group and 7 of 52 in the nonactivated group. These are separate from the serious adverse event counts and should not be described as serious events. The record does not give further details of those events in the listed summary, nor does it identify their types or timing. Death counts are not reported in the registry record.

General explanation: an observed count of zero serious events means that none were recorded in the stated group and denominator; it does not establish that the underlying risk is zero. Safety interpretation also depends on the event definitions, follow-up, ascertainment, and completeness of reporting. The registry record does not provide enough detail to evaluate those features or to infer whether the groups differed in safety.

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

The registry record establishes that a randomized, quadruple-masked crossover study was conducted to examine temporary gastric electrical stimulation in people with drug-refractory gastroparesis. It identifies a patient-reported vomiting symptom score as the primary outcome and lists baseline and later study measurements. The study summary states a hypothesis about a decrease in gastrointestinal symptoms when the device was on.

Those design and outcome descriptions do not establish what the study found. Numerical primary-outcome results, a condition contrast, and measures of uncertainty are not reported in the registry record. The stated hypothesis must not be mistaken for a result. It is not possible to say from this record whether the vomiting score improved, worsened, or was similar across conditions, or how precisely any difference was estimated.

General explanation: even when a trial reports an observed difference, interpretation requires attention to its size, uncertainty, outcome definition, analysis population, and design. A score change over time is not necessarily evidence of a condition effect, especially when the timing and period structure matter. In this crossover study, the record does not describe the primary analysis sufficiently to assess how those features were addressed.

The safety summary reports zero serious adverse events in each listed group, alongside other adverse event counts. Those figures describe the registry’s recorded events in the stated denominators; they do not answer the primary efficacy question or rule out unrecorded or uncommon harms. Overall, the record provides information about the trial’s intended design and some safety counts, but not the primary results needed to quantify symptom differences.

13. Why This Trial Matters Statistically

This study illustrates why a registry description and a result are not interchangeable. The record identifies a specific clinical question, a randomized crossover design, masking, and a patient-reported endpoint. Those details allow readers to understand the intended comparison, but without the numerical outcome results they cannot evaluate its magnitude or precision. The distinction is important whenever a study summary states a hypothesis: a hypothesis describes what investigators expected to examine, not what the data demonstrated.

The crossover structure also highlights statistical questions that are easy to overlook. Repeated observations from the same participant can be useful, but the analysis must account for the relationship among those observations and the order in which conditions occur. Period effects, carryover, and incomplete data can influence interpretation. The registry record mentions a wash out but does not report the analysis choices or the handling of these issues.

The endpoint further shows why outcome definition matters. A patient-reported vomiting score is not interchangeable with a measure of stomach emptying or with a broader measure of gastrointestinal symptoms. The record names a specific symptom score while the stated hypothesis refers to gastrointestinal symptoms more broadly. Without reported results and analysis details, the connection between those descriptions cannot be assessed.

Finally, the safety counts and enrollment total answer different questions. Enrollment does not identify the number analyzed for the primary outcome, and zero recorded serious adverse events does not establish zero risk. Reading these elements separately helps keep the conclusions proportionate to what the registry record actually reports.

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 for interpretation is that the registry record does not report numerical primary-outcome results or an analysis. No observed mean scores, treatment contrast, confidence interval, or p-value are available for the listed vomiting symptom endpoint. As a result, the effect’s direction, size, and precision cannot be described.

The arm descriptions are truncated. They indicate active and sham or nonactivated periods, including a 72 consecutive hours of active stimulation, a 1 day wash out, and a crossover, but they do not provide a complete account of the protocol. The record does not report details needed to assess sequence generation, allocation concealment, the masking procedures, or how the washout was justified.

The record lists 3 outcome measures and multiple time points for the primary symptom measure, but it does not report a multiplicity plan or identify the specific primary contrast. It lists 0 analyses and does not describe the statistical model, handling of period or carryover effects, missing-data methods, or analysis populations. Participant flow and the number contributing outcome data are not reported in the registry record.

The overall enrollment of 58 does not show how many participants completed each crossover period or contributed paired observations. The adverse-event denominators differ from the enrollment figure, but the record does not explain that difference. Safety reporting also lacks event-level details in this summary, and death counts are not reported in the registry record. These limitations mean that neither the primary comparison nor the completeness of outcome and safety ascertainment can be evaluated from the recorded information alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Temporary Gastric Electrical Stimulation for Drug Refractory Gastroparesis — NCT00432835.
• Registry record last updated 2012-12-03; status last verified 2012-11.
• Results first posted 2012-12-03.
• 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

The registry record describes a completed Phase 3, randomized, quadruple-masked crossover study of temporary gastric electrical stimulation for drug-refractory gastroparesis. Enrollment was 58. The primary outcome was a patient-reported vomiting symptom score on a Likert Scale 0-4, with measurements listed for Study Day 0 (Baseline), Day 3, and Day 7.

The record describes active and sham or nonactivated stimulation sequences, including a wash out and crossover. It does not report numerical primary-outcome results, a primary analysis, or a detailed statistical analysis plan. The safety summary lists 0 serious adverse events among 51 participants in the activated group and 0 among 52 in the nonactivated group, with other adverse events reported for 6 and 7 participants, respectively. Death counts are not reported in the registry record.