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 PS128 May Improve Off Duration on Parkinson's Disease (NCT04389762), a na na study. The primary outcome is Change in Unified Parkinson's Disease Rating Scale (UPDRS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04389762 |
| Phase | NA |
| Condition | Parkinson Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 26 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Professor Lu Neurological Clinic |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns participants with Parkinson disease. The registry records enrollment of 26 participants and says that participants who completed the 12-week intervention were analyzed for the primary outcome. Other eligibility details and the number who completed the intervention are not reported in the registry record.
Intervention
Participants received daily Lactobacillus plantarum PS128 capsules. The study description frames this as an investigation of short-term effects over 12 weeks. The registry classifies the intervention as a dietary supplement. Further details about dose or adherence are not reported in the registry record.
Comparator
This is a single-group study, and the registry does not identify a control group or randomized allocation. A like-for-like comparison with placebo, usual care, or another treatment is therefore not part of the registered design. Change over time in the study group is not the same as a controlled treatment contrast.
Primary question
The primary outcome is change in the Unified Parkinson's Disease Rating Scale (UPDRS), assessed on medication from baseline to Week 12. The scale is used to gauge Parkinson's disease course; higher scores represent a worse outcome. The registry record does not report the observed change or its uncertainty, so it does not establish the size or direction of the study's primary result.
3. Trial Design
The registry describes a completed pilot study of daily Lactobacillus plantarum PS128 in Parkinson disease. It lists an enrollment of 26 and a single-group model. Allocation is recorded as NA, and masking is recorded as NONE. The study began on 2019-06-04, reached primary completion on 2020-05-13, and has a status of COMPLETED. These registration details describe the planned and recorded study structure; they do not supply outcome results.
With a single group, the primary outcome is framed as change within participants from baseline to Week 12, assessed on medication. The intervention is daily ingestion of PS128 capsules. The registry does not describe a concurrent comparator, randomization, or masking. Consequently, a change during the intervention period cannot by itself distinguish an intervention-associated change from other influences, such as changes over time or features of measurement and care. This is a design limitation, not evidence about whether the outcome changed.
The primary analysis population is described as participants who completed the 12-week intervention. The registry does not report how many participants completed it, how missing measurements were handled, or whether all enrolled participants contributed data to every outcome. It lists eight outcome measures and seven analyses, including secondary outcomes concerning nonmotor symptoms, the Parkinson's Disease Questionnaire, and Patient Global Impression of Change. Details linking each analysis to its outcome are not reported in the registry record.
The registry identifies the study as a pilot, but does not report a sample-size justification or enough design information to assess a prespecified target for precision. The posted record also does not report a protocol-based statistical analysis plan. Its planning illustration assumptions are not a substitute for the study's own design rationale.
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 | PS128 |
|---|---|
| STARTED | 26 |
| COMPLETED | 25 |
| NOT COMPLETED | 1 |
Analysis population for the primary outcome, as defined in the registry: Participants who completed the 12-week intervention were analyzed.
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.
Population: Parkinson's disease patients between ages of 40-80 years old, according to the record of ON / OFF diary for 3 consecutive days, the patient's daily off periods must be more than 3 hours a day.
| Characteristic | Unit | PS128 |
|---|---|---|
| Participants analysed | 25 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 22 |
| Age, Categorical: >=65 years | Participants | 3 |
| Sex: Female, Male: Female | Participants | 8 |
| Sex: Female, Male: Male | Participants | 17 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: Taiwan | participants | 25 |
| Age at onset | years | 51.72 (SD 6.59) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Unified Parkinson's Disease Rating Scale (UPDRS), measured over Baseline to Week 12 assessed on medication.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in the Unified Parkinson's Disease Rating Scale (UPDRS) from baseline to Week 12, assessed on medication. The registry describes UPDRS as a rating tool used to gauge the course of Parkinson's disease. The scale ranges from 0 to 199, and higher values represent a worse outcome. This makes the score a way to quantify clinical status on a common scale, while the change endpoint asks how the score differs between the stated assessments.
The registry characterizes the endpoint as a mean of a continuous measure and identifies standard deviation as its dispersion measure. A mean describes the average score or change in the analyzed group; a standard deviation describes how spread out individual values are around that average. Neither is reported as an observed primary result in the registry record. Thus the scale's meaning and the planned assessment interval are available, but the actual average change and variation are not.
The primary population is described as participants who completed the 12-week intervention. Restricting an analysis to completers can make the analyzed group differ from the enrolled group if completion is related to symptoms, tolerability, or other factors. Whether that occurred, and how any missing endpoint values were addressed, is not reported in the registry record. The endpoint definition therefore tells readers what was intended to be measured, but not how complete or representative the resulting data were.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted registry record does not report a numerical result for change in UPDRS. It does not give the group mean change, a standard deviation for change, a confidence interval, or a p-value. As a result, the primary outcome's direction, magnitude, and precision cannot be assessed from this record. A description of the measure and the assessment schedule is not itself evidence of an observed change.
The design also limits what a within-group comparison could establish. Participants were assessed at baseline and Week 12 in a single-group study, with no registered control group. Even if a before-and-after change were reported, that pattern alone would not isolate an intervention effect. General influences on scores over time, changes in care, expectations, measurement variation, and selective completion can also contribute to observed change. The registry information does not allow those possibilities to be separated.
The analysis population is stated to include participants who completed the 12-week intervention, but the number analyzed is not reported in the registry record. Enrollment of 26 is not interchangeable with the number contributing endpoint data. Without the analyzed count and information about missing data, readers cannot judge how much data support the endpoint or whether attrition could affect its interpretation.
The registry lists secondary outcomes involving the NMS-Quest total score, PDQ-39, and PGI-C, and records eight outcome measures and seven analyses. It does not report results for those outcomes in the information available in the record. Their presence signals that the study considered more than the primary endpoint, but no conclusion about those measures can be drawn from their names alone.
The adverse-event figures are also descriptive registry entries, not a comparison with another group. The single PS128 group records no serious adverse events, no other adverse events, and no deaths among the participants listed as at risk. With no control group and no further safety detail reported, these entries should not be interpreted as demonstrating comparative safety or excluding harms. They describe what the registry reports for this group.
In short, the record establishes the study question, intervention, design, endpoint definition, and some safety counts. It does not provide enough outcome information to characterize the observed primary effect or its uncertainty. Any interpretation should distinguish the registered plan and group description from unreported outcome findings.
9. Statistical Methods Explained
The methods information in the registry record is limited. It identifies a continuous primary endpoint summarized as a mean with standard deviation, an assessment from baseline to Week 12 on medication, and an analysis population of participants who completed the 12-week intervention. It does not report the statistical test or model used, whether baseline and follow-up values were analyzed as paired observations, how covariates were handled, or how uncertainty was estimated. Those details should not be inferred from the endpoint label.
What does a mean change describe?
In general, a mean change represents the average difference between measurements at two times for the people included in an analysis. It gives a concise description of the group's direction and typical magnitude, but can conceal variation among individuals. The registry indicates that UPDRS change is the primary outcome and that the measure is continuous. It does not state the mean change, so readers cannot tell whether the posted average moved toward higher or lower scores.
In general, a standard deviation describes the spread of individual observations around a mean. It is not the same as the precision of the estimated mean. Precision is often conveyed by a confidence interval, which gives a range of estimates compatible with the data under the method's assumptions. A confidence interval for the primary change is not reported in the registry record. Neither the spread of individual changes nor the precision of the mean can therefore be evaluated from the primary result information in this record.
Why does the single-group structure matter?
A before-and-after analysis can describe how a measured group changed between two assessments. A treatment effect, however, is a comparative concept: it asks what happened with the intervention relative to what would have happened without it, or relative to another assigned condition. The registry identifies a single-group model and does not identify a comparator. General changes over time, measurement variability, and participant expectations are among the reasons an observed before-and-after pattern cannot automatically be attributed to the intervention. The record does not state that any particular method was used to address these issues.
The registry says the endpoint was assessed on medication at baseline and Week 12. Keeping the medication status consistent at assessments can be relevant to interpreting scores, but the record does not provide further details about assessment procedures or medication management. It also does not report whether timing, assessors, or other conditions were standardized. No additional procedure should be assumed.
What does the analysis population tell readers?
The stated primary population consists of participants who completed the 12-week intervention. In general, a completer analysis describes people with the required follow-up information, but it may not represent everyone enrolled if completion is related to outcome or participant characteristics. The registry reports enrollment of 26, but does not report the number of completers or the number with observed primary endpoint data. It also does not report reasons for noncompletion or whether any imputation, sensitivity analysis, or other missing-data approach was used.
These omissions matter because missing measurements can affect both the estimated average and its uncertainty. A complete-case result, if that was the method, would rely on the observed data of those included. Other approaches require assumptions about the unobserved values. Since the registry does not identify the method or its assumptions, readers cannot assess whether missingness was addressed or how robust the result would be to alternative assumptions. Moreover, no numerical primary result is reported for any population in the record.
How should multiplicity be understood?
Multiplicity arises when several outcomes, comparisons, or analyses are considered. In general, conducting multiple statistical tests can increase the chance that at least one result appears noteworthy by chance, unless the analysis plan addresses that issue. The record lists eight outcome measures and seven analyses, and names secondary measures concerning NMS-Quest, PDQ-39, and PGI-C. It does not describe a multiplicity adjustment, hierarchy among outcomes, or a prespecified strategy for interpreting multiple findings. The counts alone do not establish how the analyses were organized or whether any adjustment was planned.
What can planning assumptions establish?
The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect, and distinguishes participants per arm for non-time-to-event outcomes from total events for time-to-event outcomes. Those are assumptions for an illustration, not evidence that the pilot used that design or had a particular power. The registry record does not report the illustration's calculated sample sizes in the information available for this analysis, nor a trial-specific sample-size justification. Such planning calculations should never be treated as observed power or as a substitute for the observed treatment estimate and its uncertainty.
Overall, the record supports a limited methodological description: a single-group pilot, a continuous UPDRS change endpoint, a stated completer population, and several registered outcome measures. The model, test, variance estimation, missing-data procedures, multiplicity handling, and numerical outcome results are not reported in the registry record. General statistical concepts can clarify what those methods would mean, but cannot fill in the study-specific details that are absent.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists eight outcome measures and seven analyses. It names secondary outcomes covering change in NMS-Quest total score, change in PDQ-39, and PGI-C. The record does not explain the mapping between outcomes and analyses, identify a hierarchy among endpoints, or report whether statistical tests were adjusted for multiplicity. In general, when multiple outcomes are examined, the chance of a chance finding can increase; a prespecified strategy helps clarify how findings should be interpreted. No such strategy is reported in the registry record.
The primary analysis population is described as participants who completed the 12-week intervention. Enrollment is recorded as 26, but the number completing the intervention and the number with primary outcome data are not reported in the registry record. Reasons for missing data, withdrawal information, and methods for handling missing measurements are also not reported. The record does not state whether analyses were limited to observed cases, used imputation, or included sensitivity analyses.
These gaps constrain interpretation. In general, excluding participants without follow-up data can affect the estimated change if those participants differ systematically from completers. Methods for addressing missing values also depend on assumptions that should be described. Without the analysis count, missingness details, and outcome results, the reader cannot evaluate the potential impact of incomplete follow-up or how uncertainty was handled. The record also does not report a statistical analysis plan that would clarify whether choices were set before outcome data were examined.
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 |
|---|---|---|---|
| PS128 | 0 | 26 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| PS128 | 0 of 26 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| PS128 | 0 of 26 |
The registry's safety entries list the PS128 group as having 26 participants at risk for serious adverse events and 0 affected. It also lists 26 at risk for other adverse events and 0 affected, with 0 deaths. No top serious adverse-event terms are listed. These are the registered counts for the study group; they are not a comparison with a control group.
Zero recorded events in these entries means that the registry reports no events in the specified categories for the participants it lists as at risk. It does not establish that risk is absent or that an intervention is safer than an alternative. In general, safety interpretation depends on the amount and completeness of follow-up, how events were defined and collected, and the precision of estimates. The registry record does not report further details about event ascertainment, exposure duration for safety assessment, or uncertainty around these counts.
The study is single-group, and the record does not provide a comparative safety estimate. The listed figures should therefore be read as descriptive registry reporting, not proof of no harm and not a basis for a treatment recommendation.
12. What the Result Does, and Does Not, Mean
The registry record establishes that this completed pilot study investigated daily Lactobacillus plantarum PS128 capsules in people with Parkinson disease. It identifies change in UPDRS from baseline to Week 12, assessed on medication, as the primary outcome and defines higher scores as worse. It also records the intended analysis population as participants who completed the intervention.
What the record does not establish is the actual primary outcome result. The mean change, standard deviation, confidence interval, and p-value are not reported in the registry record. Without those findings, it is not possible to describe the observed direction or size of change, or how precisely it was estimated. Endpoint definitions and study completion status do not substitute for outcome data.
The design also does not provide a registered control-group comparison. In general, change within a single group cannot by itself show that an intervention caused the change. Other influences over time, measurement variability, and selective completion may contribute. This limitation remains even if a before-and-after difference is eventually reported; a comparative design is needed to directly assess outcomes under different assigned conditions.
The registry lists secondary outcomes and descriptive safety counts, but does not report results for the secondary outcomes in the information. The safety entries record no serious adverse events, other adverse events, or deaths in the listed PS128 group. Those counts are not a comparison, and the record does not include enough follow-up or ascertainment detail to treat them as evidence that risk is absent.
Accordingly, the record supports conclusions about what was studied and how the primary endpoint was defined, but not a conclusion about the intervention's efficacy or comparative safety. This is not medical advice; it is a boundary on what can be inferred from the registry information.
13. Why This Trial Matters Statistically
This study is statistically relevant because it illustrates the distinction between a registered question and a reported result. The registry identifies a clinically meaningful rating scale, an assessment interval, and a target analysis population, but does not report the primary estimate or its uncertainty. Readers need the numerical outcome information to judge the magnitude and precision of any observed change. A completed status alone does not answer the study question.
The single-group design also highlights the difference between describing change and estimating a comparative effect. Within-group change can be informative as a descriptive observation, but without a control group it cannot separate the intervention from other influences on measurements over time. This distinction is important when interpreting pilot studies and when deciding what further evidence a design would need to provide.
The record's statement that completers were analyzed brings attention to analysis populations and missing data. Enrollment does not reveal how many participants contributed to the primary outcome, and the registry does not state how missing measurements were handled. These details affect how readers assess representativeness and precision. The list of multiple outcomes also raises questions about prespecification and multiplicity that the record does not resolve.
Finally, the safety counts demonstrate why descriptive zero-event entries should be interpreted cautiously. They record what was reported for a single group, without a comparator or further ascertainment detail. The statistical lesson is to distinguish the scope of registry reporting from the strength of the conclusions it can support.
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.
Several limitations are specific to the information recorded for this study. It is a single-group pilot with allocation recorded as NA and masking recorded as NONE. The registry does not identify a comparator, so the design does not support a direct between-group treatment contrast. Any within-group change, if reported elsewhere, would remain open to explanations other than the intervention.
The primary outcome is described as baseline-to-Week 12 UPDRS change assessed on medication, but the registry record does not report the numerical result. It also does not report an uncertainty interval, p-value, or the number of completers contributing to the endpoint. The stated analysis population is limited to participants who completed the intervention, and missing-data handling is not reported. These omissions prevent assessment of outcome precision and the potential influence of incomplete follow-up.
The record lists eight outcome measures and seven analyses, but does not describe the analysis plan, how analyses correspond to outcomes, or whether multiplicity was addressed. It also does not report a trial-specific sample-size justification. The planning assumptions recorded for an illustration do not establish the study's design rationale or observed power.
For safety, the registry records no serious or other adverse events and no deaths in the PS128 group, but provides no control group or further event-collection and follow-up details. The absence of listed events should not be generalized beyond those registry entries. These limitations concern what the record can establish; they do not determine what unreported study materials may contain.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: PS128 May Improve Off Duration on Parkinson's Disease — NCT04389762.
- Registry record last updated 2025-08-17; status last verified 2025-07.
- Results first posted 2025-06-25.
- 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
NCT04389762 is a completed pilot study of daily Lactobacillus plantarum PS128 capsules in Parkinson disease. The registry records enrollment of 26, a single-group model, allocation NA, and masking NONE. The primary outcome is change in UPDRS from baseline to Week 12, assessed on medication, with higher scores indicating a worse outcome. The primary analysis population is described as participants who completed the 12-week intervention.
The record lists eight outcome measures and seven analyses and names secondary outcomes involving NMS-Quest, PDQ-39, and PGI-C. It records no serious adverse events, other adverse events, or deaths in the PS128 group. The numerical primary outcome result, its uncertainty, the number of completers, and the methods for missing data and multiplicity are not reported in the registry record. The single-group design does not provide a registered control comparison.