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 Treating H. Pylori in Parkinson's Patients With Motor Fluctuations (NCT00664209), a randomized phase 3 study. The primary outcome is "Off" Time.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00664209 |
| Phase | Phase 3 |
| Condition | Parkinson's Disease, Helicobacter Infections, Motor Fluctuations |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 64 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of California, Los Angeles |
| Results posted | Yes |
2. Clinical Question
Population
People with Parkinson’s disease, Helicobacter pylori infection, and motor fluctuations were the intended study population, according to the registry description. The registry lists enrollment as 64. The endpoint population entry says “Participants did not return symptom diaries”; the record does not clarify whether this describes participants without endpoint data, an analysis population, or another aspect of the outcome record.
Intervention
The active regimen is recorded as “clartihromycin, amoxicillin, and omeprazole,” described in the study summary as treatment for H. pylori. The active-placebo arm description says active triple therapy was followed by placebo therapy.
Comparator
The comparator was placebo therapy. The placebo-active arm description says placebo therapy was followed by active triple therapy. Those descriptions give treatment sequences, although the registry also classifies the study model as parallel.
Primary question
The primary outcome was average total daily “off” time, measured by patient symptom diaries in hours, at 2 months. The question was whether H. pylori treatment was associated with a change in that measure compared with placebo. The registry record does not post an estimated treatment effect or an analysis comparing the groups, so the clinical question cannot be answered from the posted results.
3. Trial Design
The registry describes a Phase 3 randomized trial with quadruple masking and a parallel model. The listed enrollment is 64. The sponsor is the University of California, Los Angeles. The recorded start was 2008-01, and primary completion was 2011-06. The current registry status is terminated. The reason for termination is not reported in the registry record.
The listed interventions are active triple therapy and placebo. The active regimen is spelled “clartihromycin, amoxicillin, and omeprazole” in the registry record. The arm descriptions specify active treatment followed by placebo in one arm and placebo followed by active treatment in the other. This sequence-based wording does not align clearly with the registry’s parallel-model classification. The record does not explain this distinction, so the design should not be characterized more specifically than the available descriptions allow.
Randomization means assignment to treatment groups is intended to reduce systematic differences between groups at the point of assignment. Masking is intended to limit the influence of treatment knowledge on care, reporting, or assessment. The registry states that masking was quadruple, but does not identify which roles were masked or describe how masking was maintained.
The primary outcome was “off” time over a timeframe of 2 months. Four secondary outcomes are listed: change in UPDRS total scores, change in UPDRS Part III, quality of life assessed by PDQ-39, and participants with side effects from study treatment. The record lists 5 outcome measures in total, but it does not provide results for these outcomes. No statistical analysis results are posted.
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: Of 64 enrolled, 13 positive for H. Pylori were screened for motor fluctuations (wearing off of the benefits of levodopa).
Motor Fluctuations Screen
| Stage | Active |
|---|---|
| STARTED | 13 |
| COMPLETED | 6 |
| NOT COMPLETED | 7 |
Reasons for not completing this period:
| Reason | Active |
|---|---|
| Negative for motor fluctuation | 7 |
Study Treatment Period
| Stage | Active |
|---|---|
| STARTED | 6 |
| COMPLETED | 0 |
| NOT COMPLETED | 6 |
Reasons for not completing this period:
| Reason | Active |
|---|---|
| Physician Decision | 4 |
| Withdrawal by Subject | 2 |
Analysis population for the primary outcome, as defined in the registry: Participants did not return symptom diaries
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Active |
|---|---|---|
| Participants analysed | 13 | |
| Age, Continuous | years | 62.4 (51 to 73) |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 10 |
| Region of Enrollment: United States | participants | 13 |
6. Primary Endpoint
The registry lists the primary outcome as "Off" Time, measured over 2 months.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is average total daily “off” time, expressed in hours and assessed using patient symptom diaries. In Parkinson’s disease, “off” time refers to periods when symptoms are not adequately controlled by the person’s medication regimen; the registry uses the term as the endpoint label but does not provide a more detailed operational definition. Diary measurement is intended to capture patients’ experiences across daily life rather than relying only on a brief clinic assessment.
Daily symptom diaries can be useful when an outcome varies over the day and when participants’ own records are needed to estimate how long those periods last. The resulting measure depends on diary completion, participants’ understanding of the recording instructions, and the timing and accuracy of entries. These are general considerations for diary-based endpoints, not additional details reported about this trial.
The registry gives a timeframe of 2 months and describes the measure as average total daily “off” time in hours. It also records “Participants did not return symptom diaries” in the endpoint population information. This makes the availability or interpretation of the endpoint data uncertain from the registry record. The record does not state how many diaries were missing, how missing entries were handled, or whether an endpoint estimate could be calculated. No group estimates or comparison results are posted.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the registry record contains no posted analysis results. It lists the primary outcome and its timeframe, but does not give an outcome estimate, a difference between treatment groups, a confidence interval, a test statistic, or a p-value. The posted record therefore does not establish the size, direction, or precision of any treatment-group contrast in daily “off” time.
The outcome description also flags symptom-diary non-return. A diary-based endpoint can only be interpreted when the amount and pattern of missing information are understood. The record does not report how many participants did not return diaries, whether missingness differed between groups, or how the analysis addressed missing data. Without those details and without an outcome analysis, it is not possible to determine whether the registered primary endpoint was analyzed or what the result would mean.
The trial is registered as terminated, but the reason for termination is not reported in the registry record. Termination alone does not explain whether the study stopped because of recruitment, operational, safety, funding, or other considerations. None of those explanations should be inferred. The registry lists enrollment as 64; that number does not by itself show how many participants completed treatment, returned diaries, or entered an outcome analysis.
The registry lists four secondary outcomes, including motor assessment scores, quality of life, and side effects. No outcome results are posted for these measures either. The record also lists 0 analyses. That means the registry entry does not supply analysis findings that can be used to compare the treatments. It does not mean that no analysis was ever performed outside the registry.
Consequently, the information supports a description of the intended clinical question and the registered design, not a conclusion about whether the active regimen changed “off” time or any secondary outcome. In general, an estimate is more informative when accompanied by a confidence interval, because the interval communicates uncertainty about the effect’s magnitude. Neither an effect estimate nor such an interval is reported in the registry record. The same limitation applies to statistical significance: no p-value is posted, and statistical significance cannot be inferred from the trial’s design, status, or enrollment listing.
The arm descriptions identify treatment sequences, while the registry classifies the model as parallel. That unresolved design wording further limits a precise reconstruction of the intended comparison. A reader should avoid treating the registry description as proof of a particular sequence analysis or assuming that the record provides a simple parallel-group contrast. The available information does not resolve the issue.
9. Statistical Methods Explained
Statistical methods determine how outcomes are summarized, how treatment groups are compared, and how uncertainty is communicated. The registry record gives design labels and an outcome description, but does not report the analysis methods used for this trial. The explanations below are general statistical context; they should not be read as a description of methods documented for this study.
What does randomization contribute?
In general, random assignment is used to make treatment groups comparable in expectation with respect to both measured and unmeasured characteristics. It does not guarantee identical groups in a particular trial, especially when the available sample is limited. The value of randomization depends on preserving the assigned groups in the analysis and reporting how participants were handled after assignment. The registry identifies the trial as randomized but does not describe the randomization procedure, allocation concealment, analysis population, or handling of deviations from assigned treatment.
What does masking contribute?
Masking is intended to reduce the risk that knowledge of treatment assignment affects behavior, reporting, assessment, or analysis. The registry classifies masking as quadruple. It does not specify which participants, clinicians, investigators, assessors, or other roles were masked. Nor does it report whether masking was maintained or assessed. The label alone cannot establish how masking operated in practice.
How should a treatment contrast be interpreted?
For a continuous measure such as daily “off” time in hours, a treatment comparison would commonly report a group-level estimate and a contrast between groups. In general, the contrast describes how the groups differ on the outcome according to a specified analysis. Its interpretation depends on the outcome definition, the timepoint, the analysis population, and any adjustment or repeated-measure approach. The registry does not report a contrast or the method used to estimate one.
A confidence interval gives a range of values compatible with the data and the chosen statistical procedure. It communicates uncertainty about the magnitude of an estimate; it is not a guarantee that the true effect lies within the interval. A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under model assumptions. It does not describe the size or clinical importance of an effect. The registry record supplies neither a confidence interval nor a p-value for the primary endpoint.
Why can variation matter?
General statistical models make assumptions about outcome variation. If variability is greater than a model expects, the estimated uncertainty can be understated unless the analysis accounts for that extra variation. This is often discussed as over-dispersion in settings where a model assumes a particular relationship between the mean and the variance. The primary outcome is described as hours of “off” time, but the registry does not report its distribution, variability, or modeling approach. It would therefore be inappropriate to claim that over-dispersion occurred or that a particular correction was used.
Diary outcomes can also have within-person variation across days. General approaches may summarize repeated daily measurements or model them while accounting for their dependence within the same participant. The registry does not describe how daily diary records were combined into the average total daily endpoint, how many diary days were required, or how incomplete diary periods were treated. Those details are important because measurements from one person are not necessarily independent observations.
What do the planning assumptions mean?
The record describes a sample-size planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. Such calculations are planning illustrations, not evidence about the trial’s observed power and not necessarily the design rationale used by investigators. The registry record does not report the trial’s own sample-size justification. A planning calculation cannot substitute for an analysis of the results, and a target number of participants does not show whether an effect was observed.
In general, planning calculations depend on assumptions about the effect size, outcome variability, significance level, allocation, and desired power. If those assumptions do not match the study data or intended analysis, the resulting planning values may not describe the study’s actual operating characteristics. For an outcome requiring a time-to-event method, the record notes that planning tables use a total event count; other planning tables use participants per arm. These are conventions for the stated illustration, not outcome findings.
What can be concluded from the registered methods information?
The registry’s design labels and planning assumptions do not reveal which model was ultimately fitted or what estimates it produced. The analysis methods, adjustment factors, treatment of missing diary data, and definitions of analysis populations are not reported in the registry record. Because the registry lists 0 analyses and provides no outcome estimates, there is no posted statistical result to interpret. Statistical concepts can clarify what a complete analysis would ordinarily report, but cannot fill in the trial’s absent results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and four secondary outcomes. When a trial evaluates several outcomes or performs multiple comparisons, the chance of at least one apparently notable finding can increase if each is assessed independently without an appropriate strategy. General approaches include identifying a primary outcome in advance, specifying a hierarchy, or adjusting inference across a defined family of tests. The registry record does not report a multiplicity strategy, so it is not possible to say whether or how the trial addressed this issue.
The entry lists 5 outcome measures and 0 analyses. It does not post results for the primary or secondary outcomes, nor does it describe an analysis population. The registry record does not state whether an intention-to-treat, per-protocol, or other population was used. These labels have different implications for interpreting randomized comparisons, and none should be assigned to this trial without documentation.
Missing data are especially relevant because the primary endpoint population information says participants did not return symptom diaries. The record does not report the number of missing diaries, reasons for non-return, whether missingness differed between arms, or whether diaries were partly completed. It also does not describe any imputation, exclusion, sensitivity analysis, or other missing-data method. In general, missingness can affect an estimate if the participants with observed data differ systematically from those without observed data. The extent of any such effect cannot be assessed from the registry record.
The record does not report interim analyses, stopping rules, or a detailed statistical analysis plan. These details are not inferable from the listed design or terminated status.
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 |
|---|---|---|---|
| Active | 0 | 6 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Active | 0 of 6 |
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 |
|---|---|
| Active | 0 of 6 |
The adverse-event figures listed in the registry are limited to a group titled “Active.” For that group, 6 participants are listed as at risk for serious events and 0 as affected; 6 are listed as at risk for other events and 0 as affected. Deaths are listed as 0. These are the recorded figures for the displayed group and should not be read as a complete safety comparison between active therapy and placebo.
The registry record does not list corresponding figures for a placebo group, does not provide serious-event terms, and does not explain the adverse-event collection period or definitions in the information available for this record. A count of 0 affected participants in a displayed category does not establish that no events occurred in the full trial or that the treatment has no safety concerns. It describes only the entries and denominators recorded for that group. The listed at-risk counts do not establish how many participants received each treatment over the whole study or completed follow-up.
In general, safety counts are interpreted alongside the number exposed, follow-up duration, event definitions, and comparison groups. Here, the record does not provide enough detail for a balanced between-group safety assessment. The figures also cannot be used to estimate the frequency of events beyond the exact counts recorded.
12. What the Result Does, and Does Not, Mean
The registry record helps identify the study’s intended question: whether treating H. pylori in people with Parkinson’s disease and motor fluctuations would affect average daily “off” time measured by symptom diaries. It records a randomized, quadruple-masked trial, a parallel model, a listed enrollment of 64, and a 2-month primary-outcome timeframe. It also lists motor, quality-of-life, and side-effect outcomes.
Those design details are not themselves evidence of an outcome. The registry posts no treatment-effect estimate, no uncertainty interval, and no statistical test for the primary endpoint. It also posts no results for the secondary outcomes. As a result, the posted record does not show the direction or size of any difference between active treatment and placebo, or how precisely any difference was estimated.
The diary non-return note makes the primary endpoint record harder to interpret. The registry does not explain how many participants lacked diaries or how their data were handled. It also does not reconcile the treatment-sequence descriptions with the parallel-model label. These gaps limit understanding of both the available endpoint information and the intended comparison.
The record’s terminated status does not determine what the results would have been, and the reason for termination is not reported. Likewise, the listed enrollment cannot stand in for the number of participants with complete outcome data. A sample-size planning illustration is not an observed-power analysis and does not establish that a clinically important effect was present or absent.
The appropriate statistical conclusion is therefore narrow: the registry record describes a trial and its planned primary measure, but it does not provide the analysis needed to judge the treatment contrast. No conclusion about benefit, lack of benefit, or the balance of risks can be drawn from the posted outcome information alone. That is a limitation of the available record, rather than evidence in favor of either treatment.
13. Why This Trial Matters Statistically
This trial is statistically notable because its central outcome depends on patient symptom diaries, while the endpoint population information explicitly refers to participants who did not return those diaries. Diary-based measures can capture experiences that may not be represented by a single clinic assessment, but they also require a transparent account of completion and missing-data handling. Without those details, readers cannot judge how much information contributed to the endpoint or whether missing records could have influenced the comparison.
The registry also illustrates why design labels and analysis results answer different questions. Randomization and masking describe features intended to support a fair comparison; they do not reveal the result. A listed enrollment figure does not show how many observations were analyzed, and a trial status does not indicate the direction or precision of an effect. Interpreting clinical evidence requires the estimated contrast and its uncertainty, not design descriptors alone.
The coexistence of a parallel-model label and arm descriptions that specify treatment sequences is another reason to distinguish registered summaries from a fully documented protocol and analysis. The record does not explain the discrepancy. It is not possible to determine from the entry how the sequence wording was intended to relate to the study model.
Finally, this record shows the limits of a registry entry with no posted analyses. Outcomes and study characteristics can be identified, but there are no numerical treatment-effect findings to assess, and the listed secondary outcomes cannot be used to fill that gap. Statistically, the absence of estimates and missing-data details prevents evaluation of both effect magnitude and precision. The record is useful for defining what was intended to be studied, but not for judging the results.
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 registry record leaves several trial-specific uncertainties unresolved. It classifies the study as parallel, while the descriptions of the two arms refer to active therapy followed by placebo and placebo followed by active therapy. The record does not explain whether these descriptions represent treatment periods, a sequence, or another design feature. The intended structure of the comparison therefore cannot be reconstructed confidently from the entry alone.
The primary endpoint information says participants did not return symptom diaries, but it does not clarify the meaning of that statement or report the number of participants affected. There is no description of diary completion requirements, missing entries, endpoint derivation, or missing-data handling. These omissions matter because the endpoint depends on diary records.
The registry lists 64 for enrollment but does not report how many participants were randomized, treated, retained, or included in an outcome analysis. It does not identify analysis populations or provide a participant flow. The terminated status is recorded, but the reason is not reported in the registry record. The record also does not give the trial’s own sample-size justification, detailed statistical analysis plan, or multiplicity strategy.
No analysis results are posted for the primary or secondary outcomes. There is no estimate, measure of variability, confidence interval, or p-value available for interpretation. Safety information is also limited: the displayed adverse-event figures cover only a group titled “Active,” with no corresponding placebo figures or serious-event terms listed. Taken together, these gaps prevent a complete assessment of efficacy, endpoint completeness, and comparative safety from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Treating H. Pylori in Parkinson's Patients With Motor Fluctuations — NCT00664209.
- Registry record last updated 2017-12-02; status last verified 2017-10.
- Results first posted 2017-12-02.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry identifies NCT00664209 as a Phase 3 randomized trial sponsored by the University of California, Los Angeles. It lists quadruple masking, a parallel model, enrollment of 64, and a current status of terminated. The recorded start was 2008-01, with primary completion in 2011-06.
The study concerned H. pylori treatment in people with Parkinson’s disease and motor fluctuations. The primary outcome was average daily “off” time in hours, assessed by symptom diaries at 2 months. Listed secondary outcomes include UPDRS total scores, UPDRS Part III, PDQ-39 quality of life, and side effects. The endpoint population information mentions participants who did not return symptom diaries.
The registry record lists 0 analyses and does not post outcome estimates or a treatment-group comparison. It does not report the reason for termination, the handling of missing diaries, or how the treatment-sequence arm descriptions relate to the parallel-model classification. The posted information therefore describes the intended study question and selected design features, but does not establish the trial’s results.