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 Deep Brain Stimulation in Patients With Dystonia (NCT00773604), a na na study. The primary outcome is The Toronto Western Spasmodic Rating Scale (TWSTRS) Movement Scores Measured Before DBS Surgery (Baseline) and at 12 Months.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00773604 |
| Phase | NA |
| Condition | Dystonia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 9 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of California, San Francisco |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns patients with dystonia who were implanted and treated with deep brain stimulation. Its stated purpose refers to evaluating stimulation for primary dystonia. The registry lists an enrollment of 9, but the endpoint population is described specifically as patients implanted and treated; the registry record does not provide further eligibility details or a breakdown of who contributed data at each assessment.
Intervention
The intervention was deep brain stimulation using a Medtronic implantable system, targeting the subthalamic nucleus. The record identifies a treatment group receiving deep brain stimulation. It does not describe additional treatment procedures or a separate intervention group.
Comparator
There is no concurrent control group in this single-group study. The stated outcome compares the baseline TWSTRS movement score with the score at 12 months after treatment. This is a within-group before-and-after assessment, not a randomized comparison against another treatment or against no treatment.
Primary question
The primary question is how the TWSTRS movement score at 12 months compares with the score before surgery among patients implanted and treated with stimulation. The registry defines change as baseline minus the 12-month score, so a higher positive difference represents greater improvement on that score. The record does not report the numerical change or its uncertainty, so the magnitude and precision of the observed outcome cannot be assessed from the registry record.
3. Trial Design
This completed study is recorded as a single-group study of subthalamic nucleus deep brain stimulation in patients with dystonia. The registry lists an enrollment of 9 and identifies the intervention as a Medtronic implantable deep brain stimulation system. The group is described as receiving deep brain stimulation. The study began in 2008-06, and its primary completion is recorded as 2015-02.
There is no randomized allocation or masking: allocation is listed as NA and masking as NONE. The registry categorizes the model as SINGLE GROUP. Therefore, the primary endpoint is assessed by comparing participants’ measurements at baseline and 12 months, rather than by comparing outcomes between independently assigned treatment groups. A before-and-after comparison can describe change over time in the treated group, but by itself it cannot separate treatment-related change from other influences that may also change over time.
The registry lists one primary outcome measure: the TWSTRS movement score measured before surgery and at 12 months. The measure is described as a mean change with full-range dispersion, and the change is defined as baseline minus the 12-month score. The record’s stated purpose is to evaluate the safety and effectiveness of deep brain stimulation of the subthalamic nucleus for primary dystonia.
The record does not report a randomized control comparison, additional study arms, or a protocol-level account of the design rationale. The phase is listed as NA. Specific eligibility criteria, follow-up procedures beyond the stated endpoint timeframe, and the reasons for the study’s enrollment target are not reported in the registry record. The listed completion status is COMPLETED, but completion does not itself supply a numerical outcome or establish how many participants had data available for each assessment.
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 | Open Label Cohort |
|---|---|
| STARTED | 9 |
| COMPLETED | 9 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Patients implanted and treated with DBS
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 | Open Label Cohort |
|---|---|---|
| Participants analysed | 9 | |
| Age, Continuous | years | 48.95 (17 to 70) |
| Sex: Female, Male: Female | Participants | 4 |
| Sex: Female, Male: Male | Participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as The Toronto Western Spasmodic Rating Scale (TWSTRS) Movement Scores Measured Before DBS Surgery (Baseline) and at 12 Months, measured over Baseline and 12 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | TWSTRS total score change |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the change in the Toronto Western Spasmodic Rating Scale (TWSTRS) movement score from baseline to 12 months. The registry describes the total TWSTRS score as ranging from 0-88, with higher scores indicating worse symptoms. It defines the change as the baseline score minus the 12-month score. Under this direction of subtraction, a higher difference means a larger reduction in score and is interpreted in the registry description as more improvement.
A score collected before surgery provides the within-participant reference measurement, while the 12-month score describes the later assessment. Change scores are used to express how those measurements differ over time in the scale’s units. The registry characterizes the endpoint as a mean change and specifies full-range dispersion, which would describe the spread of observed changes rather than the precision of the mean estimate.
TWSTRS is used as the study’s specified measure of dystonia-related movement severity. The endpoint’s meaning depends on the scale direction and subtraction order: reading the raw score direction alone would not establish the direction of improvement. Although the registry defines the endpoint and timeframe, it does not report the mean change, its range, the number with paired measurements, or an interval estimate. The size and precision of the primary outcome therefore cannot be determined from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a relevant before-and-after outcome, but it does not give a numerical primary endpoint result. It specifies that TWSTRS movement scores were to be measured at baseline and 12 months, and that change is calculated as baseline minus the later score. It also states that higher difference scores represent more improvement. Without the mean change or the observed range, the direction and magnitude of the results for this study cannot be established from the registry record.
The record lists one primary outcome measure and zero analyses. It does not report an estimate of the mean change, a confidence interval, a p-value, or the number of participants with paired baseline and 12-month measurements. Consequently, the statistical precision of the endpoint estimate cannot be evaluated. A confidence interval, in general, describes the uncertainty around an estimated quantity under the assumptions of the analysis. No such interval is reported for this endpoint.
The design is single-group and unmasked, with no randomized comparator. The endpoint’s baseline measurement allows a within-person comparison over time, but a change from baseline does not by itself show what would have happened over the same period without the intervention. General sources of change over time, measurement variation, and other concurrent influences cannot be distinguished from an intervention effect using a single-group before-and-after contrast alone.
The registry’s enrollment is 9, while the endpoint population is described as patients implanted and treated. Enrollment does not establish that every enrolled participant contributed both measurements or was included in an endpoint analysis. The count with paired outcome data is not reported in the registry record. That distinction matters because a mean change based on incomplete follow-up may describe a subset rather than everyone enrolled.
The safety counts are separate from the primary outcome. The registry reports no serious adverse events among 9 at risk and no deaths among 9 at risk; it reports other adverse events affecting 9 of 9 at risk. These descriptive counts do not replace the missing primary outcome estimate, and they do not describe event severity, timing, or causal attribution in detail. Overall, the record specifies what was intended to be measured and reports selected safety counts, but it does not provide enough outcome detail to estimate the size or precision of the primary change.
9. Statistical Methods Explained
Statistical methods help connect an outcome definition to an estimate and clarify the uncertainty and assumptions behind that estimate. The registry describes a mean change in TWSTRS score, a full-range measure of dispersion, and a baseline-to-12-month timeframe. It does not report the numerical endpoint results or analysis details. The explanations below distinguish general statistical concepts from methods documented for this study.
What does a within-participant change measure?
In general, a change score is calculated by subtracting one measurement from another for the same participant. Here, the registry defines the subtraction as baseline minus the score at 12 months. This direction is important: the score itself is higher when symptoms are worse, but a higher baseline-minus-follow-up difference is described as more improvement. A negative difference would indicate that the later score was higher than baseline, while a difference near zero would indicate little change in the measured score. These are interpretations of the defined arithmetic, not reported findings for this study.
A mean change summarizes the average of individual changes among the participants included in that analysis. It does not show whether every participant changed in the same direction. Different individual patterns can produce the same average, so a measure of spread is useful alongside the mean. The registry calls for full-range dispersion, which generally conveys the lowest and highest observed values. Those values are not reported in the registry record.
How should precision be understood?
In general, an estimate describes the value calculated from the observed data, while its uncertainty describes how much that estimate may vary under repeated sampling and the analysis assumptions. A confidence interval is one common way to express uncertainty around an estimate. Its width is influenced by factors such as variability and the amount of usable information. A confidence interval for the primary mean change is not reported in the registry record, so readers cannot judge the precision of that estimate from the registered results.
A p-value, when reported, addresses how compatible the data are with a specified statistical null model; it is not a measure of clinical importance and does not describe the size of an effect. No primary endpoint p-value is reported. The registry lists zero analyses, so no sponsor analysis result is available in the record to interpret alongside the endpoint definition.
What can a single-group comparison establish?
In general, comparing baseline and follow-up measurements in the same group can describe observed change over time. Pairing can account for the fact that measurements from the same person are related. However, a within-group change is not equivalent to a controlled treatment contrast. In a randomized comparison, the control group can help characterize changes that might have occurred over time regardless of treatment assignment. This study has no such comparator, so the registry’s design cannot isolate the effect of the intervention from other possible explanations for change.
That limitation is about the design, not about whether a within-group change is useful to report. A before-and-after measure can describe participants’ observed trajectories. Its interpretation must remain tied to the group studied, the measurement schedule, and the absence of a concurrent control. The registry does not report adjustments for other variables or an alternative analysis intended to address this limitation.
What do the planning assumptions mean?
The registry includes a sample-size planning illustration based on a fraction of the observed effect. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration is not the trial’s own design rationale: the study is recorded as single-group, and the record does not report a protocol-based sample-size justification. The registry also states that planning values are illustrations, not observed power.
In general, a planning calculation estimates the amount of information that might be needed to detect a specified effect under chosen assumptions. It is not evidence that the study achieved that power, and it cannot replace the observed estimate and its uncertainty. Because the primary numerical result is not reported in the registry record, the size of the effect used in the illustration and the resulting planning values cannot be interpreted from the record.
The planning note distinguishes illustrations for time-to-event outcomes, expressed as total events, from other outcomes, expressed as participants per arm. The primary endpoint in this study is a score change, not a time-to-event outcome. The stated assumptions are planning conventions and should not be read as proof that the single-group study had a two-arm design.
What can be concluded from the registered methods?
The documented information supports a clear reading of the endpoint’s scale direction, subtraction order, assessment timeframe, and intended summary. It does not identify a detailed statistical analysis plan, handling of missing measurements, model specification, or inferential result. Those details are not reported in the registry record. As a result, a full assessment of analytic choices, assumptions, and robustness is not possible from the registered information.
10. Multiplicity, Missing Data and Analysis Populations
The record lists one primary outcome measure but does not report how multiplicity was addressed. In general, multiplicity arises when several outcomes, timepoints, or analyses are tested and can increase the chance of a statistically notable finding occurring by chance. A prespecified primary outcome can help focus interpretation, but the registry record does not describe any adjustment strategy, testing hierarchy, or protocol rules for selecting analyses. It is therefore not possible to determine whether additional outcomes or analyses were considered or how they were handled.
Missing-data methods are not reported in the registry record. The endpoint requires a baseline and a 12-month measurement to calculate within-participant change. The record does not state how missing follow-up measurements were handled, whether any imputation was used, or whether analyses included only participants with both measurements. The listed enrollment of 9 should not be treated as the number with complete endpoint data.
The endpoint population is described as patients implanted and treated with deep brain stimulation. The record does not further define the analysis population, describe exclusions after enrollment, or state whether all treated participants were analyzed. It also does not report a participant flow for the primary endpoint.
These omissions limit assessment of whether the analyzed group matched the intended population and whether missing observations could have affected the result. They do not establish that data were missing or that any particular method was used. The registry record simply does not report those details, and it provides no primary endpoint analysis result with which to assess them.
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 |
|---|---|---|---|
| Treatment | 0 | 9 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Treatment | 0 of 9 |
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 |
|---|---|
| Treatment | 9 of 9 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Treatment |
|---|---|---|
| Dyskinesia | Nervous system disorders | 8 of 9 |
| Depression, transient worsening | Psychiatric disorders | 5 of 9 |
| Weight gain | Metabolism and nutrition disorders | 4 of 9 |
| Anxiety, worsened | Psychiatric disorders | 2 of 9 |
| Dysarthria | Nervous system disorders | 2 of 9 |
| Dysphasia | Nervous system disorders | 2 of 9 |
| Confusion | Psychiatric disorders | 1 of 9 |
| Transient erythema around parietal incision site | Skin and subcutaneous tissue disorders | 1 of 9 |
| Subgaleal cerebral fluid collection around burr-hole cap | Surgical and medical procedures | 1 of 9 |
| Persistent pain at IPG site | Surgical and medical procedures | 1 of 9 |
The registry reports that 0 serious adverse events occurred among 9 participants at risk, and that 0 deaths occurred among 9 at risk. It also reports other adverse events affecting 9 of 9 participants at risk. These are descriptive counts recorded for the treatment group. The record lists no top serious adverse event terms.
These figures should be read as counts within the registry’s stated at-risk group, not as a complete account of each event’s nature or clinical significance. The record does not provide event descriptions, timing, duration, severity details, or an assessment of whether events were related to the device or procedure. It also does not describe how adverse events were collected or whether the same participant could contribute more than one event.
A reported count of 0 serious events does not establish that serious harms are impossible; it describes what the record reports for this study. Likewise, the other-adverse-event count does not by itself indicate severity or causality. The safety figures should therefore be kept separate from the unreported numerical primary outcome and interpreted within the limits of the registry information.
12. What the Result Does, and Does Not, Mean
The record establishes that a single-group study evaluated subthalamic nucleus deep brain stimulation in patients with dystonia and specified a baseline-to-12-month TWSTRS movement score change as its primary outcome. It defines the direction of the change so that higher baseline-minus-follow-up values mean greater improvement on the score. It also reports selected safety counts for the treatment group.
The record does not report the numerical primary outcome estimate, the range of observed changes, an interval estimate, or a p-value. It is therefore not possible to quantify the observed score change or determine how precisely it was estimated from the registry record. The listed enrollment cannot be assumed to equal the number with complete endpoint measurements or the number included in an analysis.
Even if a numerical within-group change were available, general interpretation of a single-group before-and-after result would remain limited. Changes over time may reflect the intervention, but they may also reflect other influences, and no concurrent randomized comparator is recorded. The design does not by itself distinguish among those explanations. In addition, the registry does not describe adjustment for other factors or provide analysis details that could refine interpretation.
The serious-event and death counts are descriptive, and the other adverse event count is not accompanied by details about event type or causal attribution. These counts do not establish a broader safety profile. They also do not resolve the absence of the primary outcome estimate.
Accordingly, the registry record supports a description of the study design, intended endpoint, and reported safety counts, but not a conclusion about the size or precision of the TWSTRS change. It should not be read as establishing that the intervention did or did not produce a particular clinical effect.
13. Why This Trial Matters Statistically
This trial is statistically instructive because its primary outcome is a within-participant change rather than a contrast between randomized groups. That distinction shapes what an estimate would mean. A baseline-to-follow-up change can describe the course of the treated group, while a controlled contrast is needed to compare that course with an alternative under the study design. Keeping those questions separate prevents a before-and-after result from being interpreted as though it were a randomized treatment effect.
The endpoint also illustrates why subtraction direction matters. The raw TWSTRS score is described as worse at higher values, but the registered change is baseline minus the 12-month score. With that definition, a higher change value corresponds to more improvement. Clear interpretation depends on stating both the scale direction and the calculation used.
Precision is another important issue. A mean alone would not show the variability of individual changes, while an estimate without an interval would not convey its uncertainty. The record specifies full-range dispersion but does not report the endpoint’s numerical estimate or uncertainty. This leaves a gap between an outcome definition and an interpretable result.
The record also illustrates why enrollment, analysis population, and endpoint completion should not be treated as interchangeable. The listed enrollment is 9, but the number with paired measurements and the analysis population are not reported. Missingness and analysis-population details matter because they affect which participants the estimate describes.
Finally, planning illustrations are distinct from evidence of observed precision or power. The registry describes assumptions for planning but does not report a numerical primary endpoint analysis. The statistical lesson is to read design, outcome definition, estimate, uncertainty, and analysis population as separate pieces of evidence, and to recognize when some of those pieces are not reported.
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 principal limitation for interpreting the primary outcome is that the registry record defines the TWSTRS change but does not report its numerical value. The mean change, full range, confidence interval, and p-value are not reported in the registry record. Without those results, the size, direction, and precision of the outcome cannot be assessed.
The single-group design has no randomized comparator. A baseline-to-12-month comparison can describe change in the treated group, but it cannot on its own distinguish intervention-related change from other changes over time. The study is also recorded as unmasked. The record does not report additional procedures or analysis methods that might address these design limitations.
The enrollment is listed as 9, but the number with paired baseline and 12-month scores is not reported. The endpoint population is described as patients implanted and treated, while the analysis population and missing-data handling are not reported in the registry record. This leaves uncertainty about how closely an analyzed group, if available elsewhere, would correspond to the enrolled group.
Other details needed for a fuller assessment are not reported in the registry record, including eligibility criteria, a detailed analysis plan, multiplicity procedures, and the rationale for the enrollment target. The record lists zero analyses. Safety information is also limited to event counts without detailed descriptions, timing, or causal attribution. These limitations define what can be concluded from the registry information; they do not imply that unreported methods or results were absent from other study materials.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Deep Brain Stimulation in Patients With Dystonia — NCT00773604.
- Registry record last updated 2019-02-19; status last verified 2019-02.
- Results first posted 2019-02-19.
- 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 registry describes a completed, single-group study of subthalamic nucleus deep brain stimulation in patients with dystonia. The intervention is identified as a Medtronic implantable deep brain stimulation system, and the listed enrollment is 9. The primary outcome is TWSTRS movement score change from baseline to 12 months, calculated as baseline minus follow-up; higher change scores are defined as greater improvement.
The registry reports 0 serious adverse events among 9 at risk, other adverse events affecting 9 of 9 at risk, and 0 deaths among 9 at risk. It lists one primary outcome measure and zero analyses. A numerical primary outcome result, its uncertainty, the analysis population, and missing-data methods are not reported in the registry record.