Pioglitazone for Idiopathic Gastroparesis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pioglitazone for Idiopathic Gastroparesis (NCT04300127), a na early/phase 1 study. The primary outcome is Severity of Gastrointestinal Symptoms as Assessed by the American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index.

2. Clinical Question

This is a within-group question: the registry describes symptom measurement during treatment, not a randomized comparison of pioglitazone with another treatment or with a control group. Consequently, any change over time, if reported, would describe the participants’ measured symptoms across the study period. Without a concurrent comparator, such a change alone could not separate a treatment-associated pattern from other influences on symptoms or measurement.

The study is described as a pilot. Its principal objective is to evaluate whether treatment for 8 weeks will improve symptoms as measured by the GCSI. The primary outcome timeframe is described separately as baseline and later monthly measurements up to 3 months. The registry record does not explain the relationship between the 8-week objective and that stated outcome timeframe.

The record lists secondary measures covering upper gastrointestinal symptom severity, functional status, blood measures, and mood. These broaden the kinds of outcomes assessed, but the registry record reports no analyses for them. Thus, the stated clinical question can be identified from the objective and outcome descriptions, while the posted results do not provide an estimate of the observed symptom change or its precision.

3. Trial Design

The registry identifies NCT04300127 as a completed study titled Pioglitazone for Idiopathic Gastroparesis, also called the PIOGAS Study. Johns Hopkins University is listed as the sponsor. The study is classified as early phase 1, with a single-group model, allocation recorded as not applicable, and no masking. The registry lists enrollment as 14.

The intervention is pioglitazone 30 mg. The arm description says candidates who are eligible after the screening period receive pioglitazone. No separate control arm is described. This is therefore not a randomized comparison, and the registry record itself notes that the arms are not a like-for-like control comparison. With a single group, the design can describe measurements among participants over time but does not directly provide a between-group treatment contrast.

The study start is recorded as 2019-10-24, primary completion as 2025-03-15, and status as completed. The record’s objective refers to 8 weeks of treatment, while the primary outcome timeframe is stated as baseline and later monthly measurements up to 3 months. The registry record does not explain this difference in descriptions, so the measurement schedule should be understood as recorded rather than reconciled by inference.

The primary outcome is the mean GCSI score, with standard deviation identified as the dispersion measure. Participants who started a time point are reported. Listed secondary measures include the Patient Assessment of Upper Gastrointestinal Symptom Severity Index, functional status assessed by the SF-36v2 Health Survey, C-reactive protein, erythrocyte sedimentation rate, and mood assessed by the Beck Depression Inventory and the State-Trait Anxiety Inventory.

The registry record does not report the detailed protocol, eligibility criteria beyond the screening description, sample-size justification, or statistical analysis plan. It lists seven outcome measures and zero analyses. The completed status should therefore not be confused with a posted report of the primary or secondary outcome results.

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.

Baseline

First Intervention - 4 Weeks Treatment

Second Intervention - 4 Weeks Treatment

Third Intervention - 4 Weeks of Wash Out

Analysis population for the primary outcome, as defined in the registry: Participants who started time point are reported

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 Severity of Gastrointestinal Symptoms as Assessed by the American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index, measured over Baseline, later monthly up to 3 months..

The primary endpoint is severity of gastrointestinal symptoms assessed with the American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index. The registry describes the result as a mean participant scale choice and identifies standard deviation as the measure of dispersion. The symptoms named in the description are nausea, early satiety, postprandial fullness, and upper abdominal pain.

Each symptom is rated from none (0) through very severe (4), based on the worst severity during the last 24 hours. The measure is intended to capture participants’ reported symptom burden associated with gastroparesis. A symptom index is useful in a study with a symptom-focused objective because it turns participants’ reports into a defined measure that can be assessed at repeated time points. This is a general explanation of the role of a patient-reported symptom measure; it does not establish that the measure changed in this study.

The registry states that the timeframe is baseline and later monthly measurements up to 3 months. It also says that reported participants are those who started the time point. These details matter when interpreting any mean: a mean describes the participants whose measurements contribute at that time point, and differences in who contributes can affect comparisons across time. The record does not report the actual means, standard deviations, participant counts at each time point, or an analysis of change.

Although the study objective refers to evaluating symptoms after 8 weeks of treatment, the posted primary outcome result is not reported in the registry record. The endpoint’s definition and scale are available, but no numerical symptom result or estimate of its precision is given.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous primary outcome summarized as a mean, with standard deviation as its measure of dispersion. A mean represents the average scale value among the participants included at a given time point. A standard deviation describes how spread out individual measurements are around that average. These are general statistical interpretations of the stated summary measures; the record does not report the actual primary means or standard deviations.

What would a mean describe?

For the GCSI, each participant rates symptom severity using the stated scale, and the registry says reported values represent the mean participant scale choice. A mean can make a group’s overall symptom level easier to describe than a list of individual ratings. However, it does not show the full pattern of responses. Participants can have different symptom experiences even when their average score is the same. The standard deviation gives some information about that variation, but does not identify each participant’s experience or explain why participants differ.

The measure is collected at baseline and at later monthly time points up to 3 months, according to the outcome description. Repeated measurement can describe how scores vary over time among participants. In general, an analysis of repeated measurements should account for the fact that measurements from the same participant are related rather than independent. The registry record does not report whether a repeated-measures model, a change-score analysis, or another approach was planned or used.

How should uncertainty be understood?

In general, a confidence interval describes a range of values compatible with the data and the assumptions of the statistical method. It helps convey precision: a narrower interval indicates greater precision than a wider interval, while neither interval guarantees that an estimate is correct. No confidence interval for the primary outcome is reported in the registry record. Without an estimate and an interval, the precision of any symptom change cannot be assessed from the posted results.

A p-value, in general, measures how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the analysis assumptions were true. It is not the probability that a treatment works, and it does not measure the size or clinical importance of an effect. The registry record reports zero analyses and no primary p-value. It is therefore not possible to assess statistical evidence for a change using a posted test result.

Why does the single-group structure matter?

This study is listed as single-group, with allocation not applicable and no masking. General statistical interpretation of a single-group study differs from interpretation of a randomized comparison. A comparison of a group’s measurements across time can describe observed within-group change, but it does not directly estimate how those measurements would have differed under a separate comparator condition. Changes over time may reflect multiple influences. The record does not describe a comparator group, so a treatment-versus-control effect cannot be estimated from this design as recorded.

Masking is also relevant as a general design consideration for outcomes based on participant reports. Knowledge of receiving an intervention can influence expectations or reporting, and symptom ratings are reported by participants. This is a general possibility, not evidence that reporting was biased in this study. The registry lists masking as none and does not provide further detail about outcome assessment procedures.

What does over-dispersion mean in general?

Over-dispersion occurs when observed variability is greater than a statistical model assumes. It can make standard errors too small and confidence intervals too narrow if the model does not accommodate the extra variation. This issue is most directly relevant to models for counts or categorical outcomes, rather than a simple mean and standard deviation for a continuous score. The record does not report a model or indicate that over-dispersion was assessed; no claim about its presence in this study is possible.

How do the planning assumptions relate to the study?

The registry’s planning convention refers to a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes illustrations based on a stated fraction of an observed effect. In general, a sample-size calculation estimates how many participants would be needed under specified assumptions to detect a target effect with a chosen level of power. Such a calculation is prospective planning, not an observed trial result. It does not show that a study had a particular probability of finding a result after it was completed.

Those planning assumptions do not match the listed single-group design with allocation recorded as not applicable. The registry record does not report a study-specific sample-size justification or a statistical analysis plan, and it gives no resulting planning estimates. The sample-size convention therefore cannot be read as evidence that the study used a two-arm design or that a particular effect was detected.

Finally, the registry identifies seven outcome measures and zero analyses. A statistical method cannot be reconstructed from outcome definitions alone. Details such as the model, handling of repeated observations, covariate adjustment, missing-data method, and criteria for interpreting results are not reported in the registry record. As a result, statistical interpretation must remain limited to the design and measurement information that is recorded.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures: the primary GCSI measure and secondary measures of upper gastrointestinal symptom severity, functional status, C-reactive protein, erythrocyte sedimentation rate, and mood assessed with two instruments. It lists zero analyses. No results for these measures, testing sequence, multiplicity adjustment, or prespecified hierarchy among secondary outcomes are reported in the registry record.

Multiplicity is a general concern when several outcomes or comparisons are examined. The more statistical tests that are conducted, the more opportunities there may be to observe a seemingly unusual result by chance. Methods such as prespecifying a primary outcome, controlling an overall error rate, or treating secondary findings as exploratory can help frame interpretation. The registry record does not report which, if any, of these approaches was used. No claim about multiplicity adjustment can be made.

Missing-data handling is also not reported in the registry record. The primary outcome description says that participants who started a time point are reported, but it does not specify how unavailable measurements were handled, why measurements might be unavailable, or whether the same participants contributed at each time point. In general, incomplete follow-up can affect both the representativeness of a mean and comparisons over time, especially if the probability of having a measurement is related to symptoms or other participant characteristics.

The analysis population is not defined in the registry record beyond the statement about participants who started a time point. It does not say whether analyses were intended to include all enrolled participants, only participants with available outcome measurements, or another group. With no reported outcome analyses or participant counts by time point, the influence of missing measurements and population selection cannot be evaluated from the posted results.

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 2% reporting threshold.

Most frequent non-serious adverse event terms

The registry’s safety figures list the Pioglitazone group as having 14 participants at risk for serious adverse events and 0 participants affected. For other adverse events, it lists 14 participants at risk and 1 participant affected. The death count is 0. These are counts in the registry record, not estimates of comparative risk: the study has no separate control group.

The serious adverse-event count should be read as a reported count, not as evidence that serious events are impossible or that the intervention caused no serious harm. The record lists no serious adverse-event terms, so it does not identify the event types or provide further event-level detail. The other-adverse-event figure indicates one participant affected, but the specific event is not reported in the registry record.

Adverse-event counts describe what the registry reports under its categories. They do not, on their own, establish whether an event was related to the intervention, how long participants were observed for safety, or whether all events were captured. Those details are not reported in the registry record. Because the study is single-group, these figures also cannot be compared with a control-group rate.

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

The registry record documents a completed pilot study of pioglitazone in idiopathic gastroparesis, with a planned focus on participant-reported gastrointestinal symptoms. It identifies the intervention, the primary measure, the stated measurement timeframe, and several secondary measures. It also records limited adverse-event counts. These details describe what the study set out to assess and what the registry reports about safety counts.

What the record does not provide is the primary symptom result. The GCSI means, standard deviations, changes from baseline, confidence intervals, and statistical tests are not reported in the registry record. It therefore does not establish the direction, magnitude, or precision of any symptom change. The absence of a posted analysis should not be treated as evidence that symptoms improved, worsened, or stayed the same.

Even if within-group measurements were available, the single-group design would not provide a direct randomized comparison with another treatment or a control condition. General interpretation of change over time must account for influences other than treatment, including natural variation and changes in participant reporting. The record does not provide evidence that separates such influences.

The study is described as a pilot, and its listed enrollment is 14. A pilot study can contribute information about the feasibility of conducting an assessment and can inform questions for later research, depending on the information collected and reported. The registry record does not report a sample-size justification, feasibility outcomes, or the results needed to evaluate those questions. The enrollment figure alone does not show the precision of an unreported symptom estimate.

The safety counts are similarly limited. The registry records 0 participants affected by serious adverse events, 1 affected by other adverse events, and 0 deaths. Those figures are descriptive and do not establish causation or comparative safety. Taken together, the record gives a clear outline of the study’s intent and design, but the absence of outcome analyses means it cannot support a quantitative conclusion about symptom change or treatment effects.

13. Why This Trial Matters Statistically

This trial is statistically notable because its central question concerns change in a patient-reported symptom measure, while the recorded design is single-group. That pairing makes it especially important to distinguish description from causal comparison. Repeated symptom measurements can characterize participants’ scores over time, but without a comparator they cannot by themselves isolate the effect of treatment from other changes occurring during the same period.

The endpoint description is useful because it specifies the symptom domains, the response scale, and the intended timing. Clear outcome definitions make it possible to understand what a future analysis would need to summarize. At the same time, the absence of posted means, variability measures, participant counts at time points, and analyses prevents readers from evaluating the actual symptom pattern or its precision.

The stated planning convention also illustrates why design and planning assumptions must be kept distinct. The convention describes two-arm equal allocation and a normal approximation, whereas the listed study is single-group with allocation not applicable. Planning illustrations are hypothetical tools and do not establish that a particular design was used, or that a study had a given observed probability of detecting an effect.

Finally, the record lists several secondary domains in addition to the primary symptom measure. Multiple outcome domains can broaden what a study assesses, but they also make the analysis plan important for interpreting any findings. The registry record does not report results, a hierarchy of outcomes, or a multiplicity approach. The statistical value of the record is therefore mainly in documenting the design and measurement framework, while also making clear that the posted information is insufficient for outcome-level inference.

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 statistical interpretation is that the registry record reports no analyses. The primary outcome is described in detail, but its results are not reported: there are no posted GCSI means, standard deviations, changes, confidence intervals, or test results. The secondary outcome results are also not reported in the registry record.

The study has a single-group design, no masking, and no separate comparator. These features limit what can be inferred from any change over time and make it impossible to estimate a randomized between-group contrast from the recorded design. The record does not describe procedures that might address alternative explanations for within-group change.

The registry lists an enrollment of 14 but does not report participant counts at each outcome time point. Its statement that participants who started a time point are reported leaves unclear how many measurements contributed at each time and whether the same participants were included across time points. Missing-data methods and the analysis population are not reported in the registry record.

The primary objective describes 8 weeks of treatment, while the primary outcome timeframe says baseline and later monthly measurements up to 3 months. The registry record does not explain this difference. It also does not report a sample-size justification, detailed statistical analysis plan, multiplicity strategy, or specific handling of repeated measurements.

Safety information is limited to registry counts. Serious adverse-event terms are not listed, and the type of the other adverse event is not reported in the registry record. Event attribution, observation details, and comparison rates are also not reported. These limitations restrict interpretation to the record’s descriptive design and counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pioglitazone for Idiopathic Gastroparesis — NCT04300127.
• Registry record last updated 2025-04-30; status last verified 2025-04.
• Results first posted 2025-04-30.
• 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

NCT04300127 is a completed early-phase 1, single-group study sponsored by Johns Hopkins University. The registry lists enrollment of 14, no masking, and pioglitazone 30 mg as the intervention. The objective describes assessing symptoms during 8 weeks of treatment.

The primary outcome is mean severity on the Gastroparesis Cardinal Symptom Index, with standard deviation as the stated dispersion measure. Its timeframe is baseline and later monthly measurements up to 3 months. Secondary outcomes include upper gastrointestinal symptom severity, functional status, blood measures, and mood measures.

The registry lists seven outcome measures and zero analyses. The primary and secondary outcome results are not reported in the registry record. Safety counts list 0 participants affected by serious adverse events, 1 affected by other adverse events, and 0 deaths. The record does not provide a separate comparator, a sample-size justification, or detailed statistical analysis methods.