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 The Stanford Parkinson's Disease Plasma Study (NCT02968433), a na phase 1 study. The primary outcome is Number of Related and Unrelated Adverse Events.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02968433 |
| Phase | Phase 1 |
| Condition | Parkinson Disease(PD) |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 16 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Stanford University |
| Results posted | Yes |
2. Clinical Question
Population
People with Parkinson disease were the study population. The official title specifies moderate Parkinson disease, and the registry lists Parkinson Disease(PD) as the condition. The study record describes neuropsychological, neuropsychiatric, and kinematic assessments before treatment. Further eligibility details and a fuller description of the enrolled population are not reported in the registry record.
Intervention
The intervention was intravenously administered plasma from young donors. The arm description states that participants received 1 unit of young plasma twice a week over a four week duration. The registry presents this as a single-group study, rather than a comparison of different treatment strategies.
Comparator
There was no concurrent comparator group in the registry record. Allocation is listed as NA, masking as none, and the model as single group. The treatment experience therefore cannot be contrasted with a control arm within this study. Comparisons with participants outside the study are not described in the record.
Primary question
The primary question concerned the number of adverse events across participants during the 8 weeks timeframe, including events that might be related to the infusion. The registry says events were categorized as probably, possibly, or not related to the study intervention. The primary outcome result itself is not reported in the registry record, so the effect estimate and its precision cannot be described. The record's safety summary lists serious and other adverse-event affected counts, but those figures do not supply the missing primary endpoint result.
3. Trial Design
The Stanford Parkinson's Disease Plasma Study is registered as a Phase 1, completed, single-group study sponsored by Stanford University. Its intervention was infusions of young plasma. The registry lists no allocation and no masking, and the study model is single group. These features identify the study as a treatment-exposure study without a concurrent randomized or other control arm. Its design can describe outcomes observed among participants receiving the intervention, but cannot estimate a treatment-versus-control contrast from within the trial.
The record describes pre-infusion neuropsychological, neuropsychiatric, and kinematic assessments. It states that participants would receive 1 unit of young plasma twice a week over a four week duration. The intervention is described in the official title as intravenous. Details beyond this excerpt of the post-infusion schedule and follow-up procedures are not reported in the registry record.
The registry lists enrollment of 16 and a primary completion date of 2019-12. The primary outcome timeframe is 8 weeks. Those are different pieces of study information: the outcome timeframe describes the period associated with that measure, while the completion date is a registry study milestone. No comparison group or masking procedure is reported. This design is suited to documenting the treatment experience and safety observations in the enrolled group, but it does not separate intervention effects from changes that could occur over time or other influences.
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 | Infusions of Young Plasma |
|---|---|
| STARTED | 16 |
| COMPLETED | 15 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Infusions of Young Plasma |
|---|---|
| Withdrawal by Subject | 1 |
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: Participants who completed the study
| Characteristic | Unit | Infusions of Young Plasma |
|---|---|---|
| Participants analysed | 15 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 8 |
| Age, Categorical: >=65 years | Participants | 7 |
| Age, Continuous | years | 63 (SD 8.3) |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 10 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 12 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Region of Enrollment: United States | Participants | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Related and Unrelated Adverse Events, measured over 8 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled “Number of Related and Unrelated Adverse Events.” It is defined as the number of adverse events across all participants that might be related to young plasma infusions as a novel treatment to Parkinson's Disease symptoms. The registry says events were categorized as probably, possibly, or not related to the study intervention. The timeframe is 8 weeks, and the unit is events.
Counting adverse events is a way to describe the safety experience during exposure and follow-up. Relationship categories can distinguish events judged more or less plausibly connected with the intervention, although the registry record does not describe the criteria or adjudication process used for those judgments. The measure is an event count, not a direct measure of symptom improvement, disease progression, or a treatment effect against a control group.
The primary endpoint's result is not reported in the registry record. The safety summary contains affected counts for serious and other adverse events, but these are not enough to recover the primary count of related and unrelated events. Nor does the record provide an event rate, uncertainty interval, or statistical comparison for this endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted record establishes the study's design and reports a limited set of safety counts, but it does not report the primary endpoint result. The endpoint was the number of related and unrelated adverse events over an 8 weeks timeframe. Without that result, readers cannot determine the total event count, how events were distributed across the relationship categories, or how precisely the endpoint was estimated. The registry also reports 0 affected in the serious adverse-event field and 13 affected in the other adverse-event field, each among 16 at risk in the single intervention group. These are descriptive safety figures; they do not provide a controlled comparison.
A count of zero in the serious affected field means that no serious adverse event was recorded for that field in this group. It does not establish that the intervention has no serious risks. A study with a single group and limited enrollment can record observed events, but the absence of an event in the record is not proof that an event cannot occur. The other affected count indicates that adverse events were recorded in that category. The record does not give event-level detail or a breakdown of those events by relatedness in the primary outcome result.
Because the study has no concurrent comparator, these counts cannot show whether the observed events were more frequent or less frequent than they would have been without the infusion. Nor can they distinguish intervention-related events from events due to the underlying condition, background health, or other factors. The registry lists no masking, so outcome assessment could also be vulnerable to knowledge of treatment, depending on how outcomes were collected. Specific assessment procedures for adverse events are not reported in the registry record.
The study's stated purpose was to demonstrate that young plasma infusions could be performed safely in people with Parkinson disease, with secondary behavioral and laboratory outcomes intended to support a later study of cognitive, mood, motor, and disease-marker questions. That stated purpose is not itself a statistical result. No analysis results are registered, and no estimates, confidence intervals, or hypothesis tests are reported. Accordingly, the record supports a narrow description of recorded adverse-event counts, not a claim about causal effects, comparative safety, or the outcomes intended for later investigation.
Interpretation should also account for the distinction between participant counts and event counts. The safety summary is organized around participants at risk and affected, whereas the primary endpoint is explicitly an event count. A participant may experience more than one event, and the available safety figures do not show whether that occurred. The registry record does not report the information needed to reconcile the affected counts with the primary event-count endpoint.
9. Statistical Methods Explained
The registry describes a single-group Phase 1 study and reports no analyses. Statistical interpretation therefore rests on descriptive information in the record rather than a reported inferential analysis. The concepts below explain what would ordinarily be useful for evaluating such results; they do not imply that these methods were used in this trial.
What does a single-group design allow?
In a single-group study, outcomes can be described among participants receiving the intervention. The design does not produce a randomized contrast against a concurrent control group. A before-and-after comparison, if reported, would still be a within-person description rather than a controlled treatment effect. Natural changes over time, other care, and differences in how outcomes are assessed can influence such observations. No before-and-after estimate or analysis is reported in the registry record.
Allocation listed as NA and the single-group model are consistent with the absence of a treatment allocation comparison. Masking is listed as none. These are design details, not evidence that a particular bias occurred. They matter because expectations or knowledge of treatment may affect reporting, assessment, or interpretation, depending on the outcome and the procedures used. The record does not describe procedures that would establish how such influences were handled.
How should an event count be understood?
An event count records how many events occurred according to the endpoint definition. It differs from a count of participants affected: one participant can contribute more than one event. A count can also be divided into categories, such as the registry's relatedness categories, but useful interpretation depends on complete reporting of the counts and the classification rules. Here, the primary endpoint result and the category-specific counts are not reported in the registry record.
For event counts, analysts may consider whether events occur at a similar average rate or whether some participants experience many more events than others. Over-dispersion is a general statistical concept: it describes count data whose variability exceeds what a simple model assumes. If present, it can make standard errors from an overly restrictive model too small and uncertainty appear narrower than it is. Whether over-dispersion is relevant cannot be determined from the available registry results, and no count model is reported.
What would an uncertainty interval add?
A confidence interval is a general way to express statistical uncertainty around an estimate under a specified model and analysis. It is not a guarantee that the true value lies inside the interval, nor does it resolve limitations in study design. For a count endpoint, an interval could help show how imprecisely the event burden is estimated. No confidence interval or other precision estimate for the primary endpoint is reported in the registry record.
A p-value, in general, summarizes how compatible data are with a specified null hypothesis under the model used. It does not measure the size or clinical importance of an effect, and it does not repair the lack of a control group. No p-values or hypothesis tests are reported among the registered analyses.
What do planning calculations mean?
Any sample-size illustrations associated with the statistical material are planning calculations, not results observed in this completed study. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of an observed effect. Such assumptions describe a hypothetical future comparison and are not this study's single-group design. The record does not report a trial-specific sample-size justification, so the illustration should not be read as the protocol's planned enrollment rationale or as observed power.
Observed power is not a useful substitute for an estimate and its uncertainty after a study has been completed. A planning calculation can help explore what a future design might detect under its assumptions, but it cannot establish what this study found. The registry record reports enrollment of 16, while providing no inferential result from which to assess the primary endpoint's precision.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 4 outcome measures and 0 analyses. It does not report a multiplicity strategy, such as a hierarchy of outcomes, an adjustment to account for multiple testing, or a prespecified distinction between confirmatory and exploratory analyses. With several outcomes, repeated testing can increase the chance of finding an apparently notable result by chance. This is a general concern; because no analysis results are reported, the record does not allow an assessment of how multiplicity affected any conclusions.
Missing-data methods are not reported in the registry record. The record does not state how incomplete follow-up, missed assessments, withdrawals, or unavailable measurements were handled, or whether any outcome data were missing. It also does not identify an analysis population, such as all enrolled participants or participants with evaluable follow-up. Enrollment and safety denominators alone do not establish which population was used for each outcome.
These omissions matter for interpretation. If outcomes are missing, the observed data may not fully represent the experience of all enrolled participants, and the direction of any resulting bias cannot be assumed. In a single-group study, analysis choices cannot create the missing control comparison. The registry does not report a statistical analysis plan, interim analyses, or sensitivity analyses, so none should be inferred.
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 |
|---|---|---|---|
| Infusions of Young Plasma | 0 | 16 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Infusions of Young Plasma | 0 of 16 |
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 |
|---|---|
| Infusions of Young Plasma | 13 of 16 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Infusions of Young Plasma |
|---|---|---|
| Skin and subcutaneous tissue disorder | Skin and subcutaneous tissue disorders | 8 of 16 |
| Involuntary movement | General disorders | 5 of 16 |
| Nervous system disturbance | Nervous system disorders | 3 of 16 |
| Musculoskeletal and connective tissue disorder | Musculoskeletal and connective tissue disorders | 3 of 16 |
| Cough | Respiratory, thoracic and mediastinal disorders | 2 of 16 |
| Urinary frequency distrubance | Renal and urinary disorders | 2 of 16 |
| Flu-like symptoms | General disorders | 2 of 16 |
| Sleep disturbance | General disorders | 2 of 16 |
| Headache | General disorders | 2 of 16 |
| Bruising | Skin and subcutaneous tissue disorders | 1 of 16 |
The registry's safety summary lists 16 at risk for serious adverse events and 0 affected in the serious field. It lists 16 at risk for other adverse events and 13 affected in the other field. These are counts within the single intervention group, not comparisons with an untreated or control group. The record does not identify a serious adverse-event term in its listed top serious terms.
“Affected” counts should not be mistaken for the primary endpoint's total event count. The primary endpoint is measured in events and includes related and unrelated adverse events, while the safety summary is organized by affected status. The record does not report the number of events experienced by each affected participant or the relationship categories for the primary endpoint. It is therefore not possible to infer the total number of primary endpoint events from the safety summary.
The zero in the serious affected field describes what was recorded in this study group; it does not demonstrate that serious events cannot occur or establish comparative safety. The other affected count indicates that events in that category were recorded, but the registry does not provide further detail about their nature, severity, timing, or relatedness. Those details are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The registry record documents a completed, single-group Phase 1 study of young-plasma infusions in people with Parkinson disease. It states that the study's main purpose was to demonstrate that the infusions could be performed safely, while behavioral and laboratory outcomes could support a later study addressing cognitive, mood, motor, and disease-marker questions. Those statements describe the study's aims; they are not findings that those aims were achieved.
The record's posted safety figures report 0 affected in the serious adverse-event field and 13 affected in the other adverse-event field, each among 16 at risk. These observations describe the recorded experience in the intervention group. They do not establish what would have happened without the infusion, and they do not prove that an adverse event is caused by or unrelated to the intervention. The primary endpoint result—the number of related and unrelated adverse events—is not reported in the registry record.
The design also does not answer whether young plasma improves or slows Parkinson disease symptoms or progression. The registry describes those questions as matters for a next study. No comparative outcome estimate, analysis result, or precision measure is reported. A single-group observation may provide information for planning and further investigation, but without a comparator it cannot isolate an intervention effect from other explanations for observed changes.
Thus, the record is informative about the study's structure, intervention schedule, stated safety focus, and limited adverse-event summary. It is not sufficient to establish efficacy, comparative safety, or the magnitude and precision of the primary endpoint. These limits reflect the design and the results reported in the registry, rather than a conclusion that an unreported outcome was favorable or unfavorable.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the distinction between documenting exposure and estimating a comparative effect. A single-group intervention study can record whether adverse events were observed among treated participants. It cannot, by design, provide a concurrent estimate of what would have occurred under a different treatment or without the intervention. The distinction is especially important when the motivating questions include whether a treatment changes symptoms or disease progression.
It also highlights the importance of matching the reported safety summary to the endpoint definition. The primary measure is an event count with relatedness categories; the safety summary reports affected counts for serious and other events. Those summaries answer different descriptive questions. Without the primary count and its categories, readers cannot substitute the affected figures for the endpoint or assess how the endpoint was assembled.
Finally, the record shows why results reporting is essential to statistical interpretation. A study can have a clearly stated objective, a defined timeframe, and recorded enrollment, yet still lack the endpoint estimate and uncertainty information needed to judge what the observations mean. The record's 0 serious affected count is a useful description of recorded events in this group, but it is not a precise estimate of risk or a comparative safety conclusion. The absence of registered analyses further limits what can be said about statistical evidence.
For future research, the registry's stated interest in behavioral and laboratory outcomes points to questions requiring prespecified definitions, transparent analysis methods, and a design able to support the intended comparison. Those elements cannot be assumed from this record. Its statistical importance lies in making clear which conclusions are descriptive and which would require more complete outcome reporting and a comparative design.
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 direct limitation is that the primary endpoint result is not reported in the registry record. Although the endpoint and timeframe are specified, the event count, relatedness-category counts, and measures of uncertainty are absent. The safety summary does not fill this gap because it reports affected counts rather than the primary endpoint's event count.
The study is single group, with no allocation comparison and no masking. Consequently, the reported safety counts have no concurrent control against which to interpret frequency, and the design cannot isolate a treatment effect. The absence of masking may matter for assessment or reporting, although the record does not describe the procedures well enough to determine whether or how this influenced outcomes.
The registry lists 16 enrolled, but the analysis population for each outcome is not reported. Missing-data handling, follow-up completeness, and reasons for any unavailable observations are not reported in the registry record. The record also lists 4 outcome measures and 0 analyses, without reporting a multiplicity plan, analysis methods, or sensitivity analyses. Further limitations include the lack of detail on adverse-event ascertainment, event-level descriptions, and the process used to classify relatedness. These gaps prevent a detailed assessment of the endpoint's reliability and precision.
Finally, the registry's stated purpose and intended future questions should not be treated as outcome findings. The posted information supports a limited description of design and safety counts, not a conclusion about efficacy, comparative safety, or the course of Parkinson disease.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Stanford Parkinson's Disease Plasma Study — NCT02968433.
- Registry record last updated 2020-12-30; status last verified 2020-12.
- Results first posted 2020-12-30.
- 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.
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18. Record Summary
The Stanford Parkinson's Disease Plasma Study is a completed Phase 1, single-group study sponsored by Stanford University. It enrolled 16 and evaluated infusions of young plasma in people with Parkinson disease. The arm description states that participants received 1 unit twice a week over a four week duration; the primary outcome timeframe is 8 weeks.
The primary endpoint was the number of related and unrelated adverse events. Its result is not reported in the registry record. The safety summary lists 0 affected in the serious adverse-event field and 13 affected in the other adverse-event field, each among 16 at risk. The record lists 4 outcome measures and 0 analyses. With no comparator group and no registered analysis results, the available information supports descriptive safety reporting but not a comparative treatment-effect estimate.