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 Trial Comparing Functional Outcomes of Awake vs. Asleep Deep Brain Stimulation (DBS) for Parkinson's Disease (NCT02401308), a randomized na study. The primary outcome is Functional Outcomes.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02401308 |
| Phase | NA |
| Condition | Parkinson's Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | St. Joseph's Hospital and Medical Center, Phoenix |
| Results posted | Yes |
2. Clinical Question
Population
People with Parkinson's disease undergoing deep brain stimulation surgery were the intended population. The registry record reports enrollment of 1 and says the study was terminated due to lack of enrollment. It does not report further eligibility criteria or a description of the enrolled participant.
Intervention
The intervention was deep brain stimulation surgery performed under general anesthesia. In the registry description, intraoperative imaging was used to verify the stereotactic accuracy of electrode placement at the time of surgery.
Comparator
The comparator was traditional awake deep brain stimulation surgery using microelectrode recordings and intra-operative stimulation. The two approaches were assigned as parallel study arms, with randomized allocation and no masking reported.
Primary question
The study proposed to examine whether functional outcomes after asleep surgery were not inferior to those after awake surgery. The primary outcome was motor function measured with the Unified Parkinson's Disease Rating Scale (UPDRS) at 6 months post-operatively in three medication and device states. No analysis was completed, so the registry record does not report an estimate of the difference or a conclusion about non-inferiority.
3. Trial Design
This was a randomized, parallel-group clinical trial with no masking reported. Its registered title describes a comparison of functional outcomes after awake versus asleep deep brain stimulation surgery for Parkinson's disease. The two arms differed in the surgical approach: the awake arm used microelectrode recordings and intra-operative stimulation, while the asleep arm used general anesthesia and intraoperative imaging to verify electrode placement.
The registry record lists enrollment as 1 and status as terminated. It states that the study was terminated due to lack of enrollment and that no analysis was completed. The record lists a start date of 2015-01-15 and a primary completion date of 2015-10-05. These dates describe the record's study timeline; they do not establish that the planned follow-up and outcome assessments were completed.
The primary endpoint was scheduled for assessment at 6 months post-operatively. Neurocognitive function and quality of life were listed as secondary outcomes. The record lists 3 outcome measures, but does not provide completed outcome analyses. It also lists no analyses. Details such as the randomization procedure, allocation concealment, eligibility criteria, sample-size justification, and the protocol's full statistical plan are not reported in the registry record.
The trial's stated purpose was to assess whether functional outcomes with asleep surgery were not inferior to those reported for traditional awake surgery. That purpose identifies the intended comparison, but it is not itself evidence that a non-inferiority test was carried out. The registry record does not report a non-inferiority margin or an analyzed comparison.
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 | Awake DBS Surgery | Asleep DBS Surgery |
|---|---|---|
| STARTED | 0 | 1 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 0 | 1 |
Reasons for not completing this period:
| Reason | Awake DBS Surgery | Asleep DBS Surgery |
|---|---|---|
| Study was terminated by the PI due to lack of enrollment. | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Study was terminated due to lack of enrollment. No analysis was completed.
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: Study was terminated due to lack of enrollment. Only 1 subject was enrolled. No analysis was completed.
| Characteristic | Unit | Awake DBS Surgery | Asleep DBS Surgery | Total |
|---|---|---|---|---|
| Participants analysed | 0 | 1 | 1 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 | 1 | 1 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 0 | 1 | 1 |
| Region of Enrollment: United States | participants | — | 1 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Functional Outcomes, measured over 6 months post-operatively.
| 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 was functional outcome measured through motor-function outcomes using the Unified Parkinson's Disease Rating Scale (UPDRS). The registry specifies assessment at 6 months post-operatively in three states: medication off with the device on; medication off with the device off; and medication on with the device on. It does not provide endpoint values, a summary measure, or an analysis of these states.
In general, a standardized clinical scale can help make outcome assessments more consistent across participants and study arms. Measuring motor function under different medication and device conditions can describe function in the particular states named in the protocol. The registry record identifies the UPDRS as an accepted metric for Parkinson's disease, but does not specify which UPDRS version or components were used, how scores would be summarized, or which of the three states would anchor the primary statistical comparison.
The registered aim was non-inferiority: to assess whether functional outcomes with asleep surgery were not inferior to those reported for awake surgery. A non-inferiority conclusion ordinarily depends on a prespecified margin, an estimate of the contrast, and its uncertainty. The margin and analysis are not reported in the registry record, and no endpoint analysis was completed. Therefore the intended measurement is clear in broad terms, but neither the observed functional outcomes nor their comparative precision can be described.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the registry record reports no completed analysis. Although it describes a randomized comparison and identifies a primary motor-function outcome, it does not report an outcome estimate, confidence interval, hypothesis test, or non-inferiority conclusion. The posted record therefore does not establish whether the two surgical approaches had similar or different functional outcomes.
Enrollment was reported as 1, and the study was terminated due to lack of enrollment. This is important context for interpreting the absence of a result: the study did not produce the planned comparative analysis in the registry record. The enrollment figure is not a basis for inferring what the outcome would have been, and it cannot support a reliable estimate of the comparison. The record does not say whether any planned endpoint measurements were collected before termination.
The study's stated non-inferiority purpose should not be mistaken for a finding. In a non-inferiority design, the question is whether the data rule out an amount of disadvantage larger than a prespecified acceptable margin. The registry record does not report such a margin or the statistical analysis, and it reports no analysis at all. Without those elements and an outcome estimate, the stated purpose remains a research question rather than a conclusion.
The adverse-event entries are also limited. The record lists zero serious adverse events, other adverse events, and deaths for the asleep arm, with 1 at risk in each of the two at-risk fields. It lists 0 at risk and 0 events in the corresponding fields for the awake arm. These entries are descriptive registry counts, not a comparative safety analysis. In particular, zero at risk in the awake arm does not offer an informative comparison of event occurrence between arms.
Any planning illustration based on an effect should be read as a hypothetical planning exercise, not as evidence of trial performance. The record's sample-size assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation, with a target effect defined as a fraction of an observed effect. These assumptions do not replace the absent trial analysis, and no observed power can be inferred. No estimated treatment contrast is reported in the registry record.
In general, estimates are more informative when paired with a confidence interval, which describes the range of values compatible with the data under the method used. Here, no such interval is reported. The absence of an interval is not evidence that the approaches are equivalent; it means that the registry record does not provide a quantified comparison. The findings are therefore best described as unavailable, rather than as positive, negative, or inconclusive evidence about functional outcomes.
9. Statistical Methods Explained
The study is described as randomized, parallel, and unmasked. Random allocation is intended, in general, to reduce systematic differences between arms at the point of assignment. A parallel design assigns participants to one study arm rather than having each participant receive both approaches as a crossover. The registry record does not describe the randomization sequence, allocation concealment, or procedures used to implement assignment, so those design features cannot be evaluated from this record.
What does the non-inferiority aim require?
The registry's brief summary says the proposed study aimed to demonstrate that functional outcomes with asleep surgery were not inferior to outcomes reported for traditional awake surgery. In general, a non-inferiority analysis compares an estimated difference with a prespecified margin. The margin defines how much disadvantage would be considered acceptable for the purpose of the study. A conclusion depends on both the direction and precision of the estimated contrast, as well as the chosen margin and analysis method. The margin, contrast definition, and analysis method are not reported in the registry record. Most importantly, no analysis was completed, so there is no estimate to compare with a margin.
Non-inferiority is not established merely by failing to detect a difference. In general, a wide interval can include both negligible differences and meaningful disadvantage, leaving the question unresolved. This distinction is especially important where there is little or no analyzed outcome information. The registry record does not report an interval or a test result for the primary outcome, so no statistical claim of non-inferiority can be assessed.
What do a confidence interval and a significance level mean?
In general, a confidence interval expresses uncertainty around an estimated effect under a specified statistical method. Its width reflects how precisely the effect has been estimated, among other factors. A significance level is a threshold used in some testing procedures to control the probability of a specified type of false-positive result under the model assumptions. The record mentions a two-sided significance level of 0.05 among assumptions for planning illustrations. This is not a reported significance test for the trial, and it does not indicate that the primary comparison was performed.
The sample-size assumptions also describe equal allocation and a normal approximation. In general, a normal approximation uses a distributional model to make calculations more tractable. Equal allocation refers to planning for the same number of participants in each arm. Neither assumption shows that the trial achieved the planned allocation or that an analysis using those methods was carried out. The registry record does not report the trial's own sample-size justification or a completed statistical analysis plan.
How should planning illustrations be read?
The registry record describes planning illustrations based on a fraction of an observed effect, with participants per arm for non-time-to-event outcomes and total events for time-to-event outcomes. Such illustrations can show how planning requirements change under stated assumptions. They are not observed trial outcomes, evidence of a trial's achieved power, or a substitute for a prespecified design calculation. The record says the illustrations are not the trial's own design. Because no primary-outcome analysis was completed, an illustration cannot be interpreted as a result of this randomized comparison.
In general, power is a design property conditional on assumptions about the effect, variability, allocation, and analysis. It is not a measure of whether a result is true, and it cannot rescue a study that has no reported outcome estimate. The record gives no trial-specific sample-size justification, and its enrollment was 1 before termination for lack of enrollment. No statement about observed power is warranted.
What can be inferred from the analysis status?
The registry record lists 0 analyses and states that no analysis was completed. It reports no primary outcome values, no group-level summary statistics, and no estimate of the awake-versus-asleep contrast. Consequently, no statistical model can be checked, no assumptions can be evaluated against residual or outcome patterns, and no sensitivity analysis can be reviewed.
Over-dispersion is a general issue for count outcomes when the observed variability exceeds that expected under a chosen count model; it can make standard errors too small if ignored. That concept does not yield a trial-specific conclusion: the registered primary outcome is a motor-function measure, and no outcome distribution or analysis is reported. More broadly, the statistical methods used for any completed analysis are not reported in the registry record because the record says no analysis was completed.
The registry names the UPDRS and its three medication/device states, but does not specify how repeated states, participant-level observations, or any potential missing assessments would be handled analytically. It also does not report a definition of the primary contrast or a method for calculating uncertainty. These details matter because different choices can target different statistical questions. Without the analysis details and results, the registered objective can be described, but its statistical answer cannot.
10. Multiplicity, Missing Data and Analysis Populations
The registry record identifies a primary outcome with measurements in three medication and device states and lists neurocognitive function and quality of life as secondary outcomes. It does not report a strategy for controlling multiplicity across the primary outcome states, the secondary outcomes, or any other comparisons. In general, testing multiple outcomes or contrasts can increase the chance of at least one apparently unusual result when each is assessed separately. A prespecified analysis strategy clarifies which comparisons are confirmatory and how results should be interpreted. No such strategy is reported in the registry record.
The record says that no analysis was completed and lists 0 analyses. It does not report outcome data, the number of participants assessed at each time point, or patterns of missing observations. The study's termination due to lack of enrollment does not by itself establish whether any outcome data were collected or lost. The extent and handling of missing data are not reported in the registry record.
The analysis population is also not described. In general, an analysis population specifies which participants contribute to a particular analysis and how departures from assigned treatment are handled. For non-inferiority questions, choices about analysis populations can be especially consequential, so the planned population and sensitivity analyses should be clear. The registry record does not report whether an intention-to-treat, per-protocol, or other population was planned or used. Because there is no completed analysis, none can be evaluated.
Details about interim analyses, multiplicity adjustment, missing-data methods, and analysis populations are not reported in the registry record. Their absence from the record should not be read as evidence that a particular method was or was not used outside the registry; it means these methods cannot be established from the record.
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 |
|---|---|---|---|
| Asleep DBS Surgery | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Awake DBS Surgery | 0 of 0 |
| Asleep DBS Surgery | 0 of 1 |
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 |
|---|---|
| Awake DBS Surgery | 0 of 0 |
| Asleep DBS Surgery | 0 of 1 |
The registry lists adverse-event counts by arm. For awake DBS surgery, it reports 0 at risk for serious adverse events and 0 serious adverse events, and 0 at risk for other adverse events and 0 other adverse events. It reports 0 deaths. For asleep DBS surgery, it reports 1 at risk in each of the serious and other adverse-event fields, with 0 serious adverse events, 0 other adverse events, and 0 deaths. No serious adverse-event terms are listed.
These are descriptive entries, not evidence from a powered comparison of safety between the procedures. The awake arm's reported at-risk counts are 0, so its zero event counts cannot be read as an estimate of event frequency among an observed at-risk group. The asleep arm's entries likewise represent very limited information. The record does not give event definitions, observation duration for adverse events, or further details about ascertainment.
In general, observing zero events does not establish that an event cannot occur, particularly when the amount of safety information is limited. The registry counts should therefore be read narrowly as the recorded counts, not as proof of absence of risk or as a comparison demonstrating one approach to be safer.
12. What the Result Does, and Does Not, Mean
The registry record establishes the study's intended comparison and reports its termination, but it does not establish a comparative functional outcome. Its primary endpoint was UPDRS motor function at 6 months post-operatively in three specified medication and device states. The record states that the study was terminated due to lack of enrollment and that no analysis was completed. There is consequently no reported estimate of the difference between awake and asleep surgery, and no uncertainty interval or statistical test to interpret.
The study's stated aim was to assess whether asleep surgery was not inferior to traditional awake surgery. That aim should not be converted into a claim that non-inferiority was demonstrated, nor into a claim that it was not demonstrated. The registry does not report a non-inferiority margin or an analysis. Without a completed comparison, the evidence does not resolve the registered question.
The enrollment figure of 1 and the adverse-event entries do not supply a substitute for the missing efficacy analysis. The registry reports zero recorded events in the listed categories, but the risk counts differ by arm and are small. Those entries cannot support a meaningful comparative safety conclusion. Nor do they establish the absence of possible events beyond the counts recorded.
In general, a lack of a reported result is different from a result showing no difference. A null finding would require outcome data and an analysis yielding an estimate, with uncertainty that could be considered in light of the study question. Here, the record offers no such estimate. The appropriate interpretation is that the registered comparison remains unanswered by the posted results.
Planning calculations, when available, describe hypothetical requirements under stated assumptions. They do not show what participants experienced and do not establish the performance of an incomplete trial. The record explicitly distinguishes its planning illustrations from the trial's own design. Those illustrations cannot be treated as observed power or as evidence for either approach.
13. Why This Trial Matters Statistically
This trial matters statistically because its stated question was a non-inferiority question, while the registry record contains no completed analysis. Non-inferiority questions require more than a general comparison of outcomes: the acceptable margin and the precision of the estimated contrast are central to interpretation. The record does not report the margin, and no contrast or uncertainty estimate is available. The example illustrates why a study's stated objective cannot be confused with a statistical conclusion.
The record also highlights the role of enrollment in producing interpretable estimates. It lists enrollment as 1 and says termination followed lack of enrollment. Randomized allocation is useful in a completed comparison, but the design label alone cannot generate evidence when no analysis is reported. A randomized trial can answer its question only to the extent that outcomes are observed and analyzed under an appropriate plan.
The endpoint was described across three medication/device states, alongside secondary outcomes for neurocognitive function and quality of life. Those multiple outcomes and states make prespecification important. The record does not report how comparisons would be prioritized or how multiplicity would be addressed. In general, transparent plans help readers distinguish the main confirmatory question from additional exploratory comparisons.
Finally, the adverse-event counts demonstrate why denominators and context are essential. Recorded zeros do not automatically mean that an arm experienced no risk, especially where the listed at-risk counts are limited or zero. Reporting the counts as descriptive entries, without overstating them as a safety comparison, preserves the distinction between absence of recorded events and evidence of comparable safety.
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 trial-specific limitation is that the registry says the study was terminated due to lack of enrollment and that no analysis was completed. Enrollment was listed as 1. No outcome values or comparative estimates are reported, leaving the primary question unanswered in the registry record.
The primary outcome description identifies UPDRS motor function at 6 months post-operatively in three medication and device states, but does not explain how those states would be combined or prioritized for the principal comparison. It does not specify the UPDRS version, scoring details, or analysis contrast. The non-inferiority margin is also not reported, which prevents assessment of the intended decision criterion even apart from the absent analysis.
The record describes randomization, no masking, and a parallel design, but does not report the randomization procedure, allocation concealment, or analysis populations. It does not provide a trial-specific sample-size justification, detailed statistical plan, missing-data strategy, or multiplicity procedure. Interim analyses are not reported in the registry record.
Secondary outcomes are named, but no results or analysis details are provided for neurocognitive function or quality of life. Safety entries have very limited at-risk counts and no further description of adverse-event ascertainment or observation. The record does not indicate whether any assessments were collected before termination, so it is not possible to characterize the completeness of outcome follow-up.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Trial Comparing Functional Outcomes of Awake vs. Asleep Deep Brain Stimulation (DBS) for Parkinson's Disease — NCT02401308.
- Registry record last updated 2021-10-26; status last verified 2021-09.
- Results first posted 2021-10-26.
- 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 record describes a randomized, parallel, unmasked trial comparing awake and asleep deep brain stimulation surgery for Parkinson's disease. Its stated objective was to assess whether functional outcomes with asleep surgery were not inferior to those with traditional awake surgery. The primary outcome was UPDRS motor function at 6 months post-operatively in three medication and device states.
The record lists enrollment as 1, status as terminated, and says the study ended due to lack of enrollment. It states that no analysis was completed and lists 0 analyses. No primary or secondary outcome estimates are reported. Neurocognitive function and quality of life were listed as secondary outcomes.
The adverse-event entries report zero events in the listed categories, with at-risk counts of 0 for the awake arm and 1 in each of the asleep arm's at-risk fields. These counts do not establish a comparative safety result. The registry record does not provide a statistical conclusion about functional outcomes or non-inferiority.