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 Using PET-CT to Target and Validate Low-frequency TMS as Treatment for Tinnitus (NCT00329524), a randomized na study. The primary outcome is Change in PET Asymmetry Index.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00329524 |
| Phase | NA |
| Condition | Tinnitus |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Double |
| Enrollment | 5 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Arkansas |
| Results posted | Yes |
2. Clinical Question
Population
The brief description concerns people with tinnitus severe enough to seek medical attention. It describes intended participants as right handed, male or female, and 19-65 years of age, with evaluation at the University of Arkansas Hearing and Balance Center. The record lists an enrollment of 5; it does not report the characteristics of those enrolled individually.
Intervention
Repetitive Transcranial Magnetic Stimulation (rTMS), described as a device intervention. The study concerns low-frequency TMS and PET-CT targeting and validation, but treatment settings and detailed procedures are not reported in the registry record.
Comparator
Sham treatment. The record says participants were randomly assigned to active and sham TMS, separated by a one-week interval. It does not describe how the sham was delivered or how treatment order was assigned.
Primary question
The primary outcome is change in the PET asymmetry index between the left and right temporal lobe, described as measured from baseline following active treatment. The registry record does not report numerical results for this outcome, so it does not establish the size or precision of any observed change.
3. Trial Design
This completed study is recorded as randomized, double masked, and crossover. In a crossover design, participants receive more than one study condition at different times, allowing outcomes under the conditions to be compared within the same participant. The registry describes active and sham treatment separated by a one-week interval. It does not report the treatment sequence, how randomization was carried out, or the details of the masking procedures.
The recorded enrollment is 5. The brief description refers to up to twenty (20) intended subjects and outlines characteristics of the planned population: right-handed people, male or female, 19-65 years old, with tinnitus severe enough to prompt medical attention. It also describes routine assessment at the University of Arkansas Medical Sciences Hearing and Balance Center, including a physical exam, hearing tests, evaluation of middle-ear status, and an MRI scan, with other possible causes to be ruled out. These details describe the study’s stated plans; the record does not confirm which procedures or eligibility characteristics applied to each enrolled participant.
The sponsor is the University of Arkansas. The recorded start is 2006-06, and primary completion is 2008-06. The phase is listed as NA. The intervention is repetitive transcranial magnetic stimulation, and the comparator is sham treatment. The primary outcome concerns PET asymmetry, while the secondary outcomes include psychomotor vigilance and the difference in Visual Analog Rating of Tinnitus following active and sham treatment.
Although the record identifies the crossover model, it does not report how the analysis accounted for repeated measurements, treatment period, treatment order, or possible carryover from one condition to the next. Those details matter because crossover comparisons depend on how within-participant observations and treatment timing are handled. The registry record also does not report the planned analysis population or explain whether all enrolled participants completed both conditions.
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 | Active Versus Sham TMS |
|---|---|
| STARTED | 5 |
| COMPLETED | 5 |
| NOT COMPLETED | 0 |
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 Versus Sham TMS |
|---|---|---|
| Participants analysed | 5 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 5 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 50 (SD 5.5) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 5 |
| Region of Enrollment: United States | participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Change in PET Asymmetry Index, measured over After active treatment week.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ratio |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in the PET asymmetry index, expressed as a ratio. The registry describes the index as calculated from the difference between the left and right temporal lobe and says the change is assessed from baseline following active treatment. The stated timeframe is after the active treatment week. The outcome is summarized as a mean with standard deviation.
In general, an imaging measure can be used to quantify a feature of brain activity or structure in a consistent numerical form. A mean describes the average observed value in the analyzed group, while a standard deviation describes how spread out individual values are around that average. These are general interpretations of the stated summary measures, not claims about the actual findings in this study.
The record does not provide the numerical baseline or follow-up values, the mean change, its standard deviation, or a confidence interval. It therefore does not allow readers to assess the direction, magnitude, or precision of the reported primary endpoint. Nor does the description establish that a change in this PET measure corresponds to a change in tinnitus symptoms. The relation between the imaging outcome and the secondary symptom rating is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the primary outcome and the study’s design, but it does not report a numerical result for the primary outcome. There is no posted estimate of the mean change in PET asymmetry, no standard deviation for that change, and no confidence interval or p-value. Consequently, the direction and size of the observed outcome, and the uncertainty around it, cannot be evaluated from the registry record.
The same limitation applies to the secondary outcomes. Psychomotor vigilance and the difference in Visual Analog Rating of Tinnitus following active and sham treatment are named, but their numerical results are not reported in the registry record. The record does not state whether these outcomes improved, worsened, or remained similar across conditions. No conclusion about a treatment effect should be drawn from the outcome names alone.
The study is recorded as completed, with enrollment of 5. Completion is a status description, not evidence that an intervention produced a particular result. The record does not state how many participants contributed data to each outcome or whether all participants completed both periods. Thus, the recorded enrollment cannot be assumed to equal the analysis sample for every outcome.
In general, a confidence interval would show a range of values compatible with the data and analysis assumptions, indicating the precision of an estimate. A p-value, if reported, would summarize how compatible the data are with a specified null hypothesis under a particular statistical model. Neither can substitute for the effect estimate itself, and neither is reported for the primary outcome in the registry record.
The description includes a sample-size planning illustration based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The resulting planning values are not included in the record details. Such illustrations are not observed power and should not be read as evidence about the actual trial results. The registry does not report the observed effect used for that illustration, so the planning assumptions cannot be connected to an observed estimate.
Because numerical outcome results are absent, the record does not support a quantitative comparison between active and sham treatment. It also does not provide enough information to assess whether the primary endpoint was analyzed according to a prespecified model or whether any reported estimate, if one exists elsewhere, accounts for the crossover structure. Interpretation is therefore limited to the trial’s recorded question, design, and outcome definitions rather than findings about the outcomes.
9. Statistical Methods Explained
The record labels the study randomized, double masked, and crossover. It does not report a statistical analysis plan, the statistical tests used, or details of the randomization and masking procedures. The explanations below describe general statistical concepts relevant to those design labels; they are not a description of unreported methods used in this trial.
What does a crossover design mean for analysis?
In general, a crossover study compares conditions experienced by the same participant at different times. Each participant can serve as their own comparison, which can reduce the influence of stable differences between people. The analysis must still account for the repeated observations from each person; treating those observations as independent would generally fail to reflect the design.
For this study, the registry says active and sham TMS were separated by a one-week interval. It does not report whether every participant received both conditions, how the order was assigned, or whether the analysis included treatment period or sequence. It also does not report whether a washout rationale or carryover assessment was specified. These omissions prevent readers from determining how the crossover structure was incorporated into the analysis.
What do mean and standard deviation describe?
The primary outcome is identified as a mean with standard deviation. In general, a mean is an average, and a standard deviation describes the variability of measured values around that average. They answer different questions: the mean locates the group’s average outcome, while the standard deviation describes spread among observations. Neither alone conveys the precision of an estimated treatment comparison. A confidence interval is commonly used to express that precision, but no interval is reported for this outcome.
The endpoint is described as change in a PET asymmetry index, but the registry record does not report the numerical observations or an analysis estimate. It also does not state whether the mean and standard deviation refer to participant-level changes, a comparison between conditions, or another summarized quantity. The wording identifies a summary measure, but not the complete calculation or model.
Why can over-dispersion matter?
In general, over-dispersion occurs when observed variability is greater than a statistical model expects. A model that understates variability can produce overly narrow uncertainty intervals or misleading significance tests. This is a general consideration rather than a reported issue in this study. The registry does not report a model or diagnostic assessment, and the primary endpoint is described as a continuous measure; no conclusion about over-dispersion can be made from the record.
What do the planning assumptions say?
The record describes planning illustrations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. It does not report the calculated planning values or the observed effect on which they depend. These assumptions describe planning illustrations only. They are not evidence of observed power, and they do not establish that the same assumptions governed the trial’s original design.
In general, a sample-size calculation estimates how much information a future study might need under stated assumptions about the effect, variability, significance level, and allocation. It is conditional on those assumptions. If an observed effect is used as a planning reference, the resulting illustration inherits uncertainty in that estimate. Here, the record does not report the observed effect or the planning outputs, so readers cannot evaluate the numerical implications.
What analysis details remain unknown?
The registry record does not report the statistical model, the test used for the primary outcome, whether estimates were adjusted for baseline values, or how repeated observations were handled. It does not report the analysis population, missing-data approach, treatment of incomplete crossover periods, or any sensitivity analyses. It also does not explain how the primary outcome’s relationship to the secondary outcomes was handled in analysis.
These are distinct methodological questions. For example, an analysis population defines which participants’ data enter a particular estimate; a missing-data method describes what happens when an expected measurement is unavailable. In crossover work, methods for incomplete periods can affect which within-person comparisons contribute. The record’s silence on these points should not be taken as evidence that a particular method was or was not used. It means the method is not reported in the registry record.
10. Confidence Intervals for Each Arm
No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Active Versus Sham TMS | 5 | 1.200 | 2.300 | -1.656 to 4.056 |
R code and output
arm <- c("Active Versus Sham TMS")
n <- c(5)
m <- c(1.2)
sp <- c(2.3)
sd <- sp # posted standard deviations
for (i in seq_along(n)) {
se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}
CARM Active Versus Sham TMS 5 1.200 2.300 -1.656 4.05611. Multiplicity, Missing Data and Analysis Populations
The registry names one primary outcome, change in PET asymmetry index, and lists psychomotor vigilance and the difference in Visual Analog Rating of Tinnitus following active and sham treatment as secondary outcomes. It also records 3 outcome measures and 2 analyses. The record does not explain how those counts correspond to the named outcomes, or identify which analyses correspond to each measure.
When several outcomes or statistical tests are examined, general statistical practice considers multiplicity: the chance of finding an apparently notable result can increase as more comparisons are made. Methods such as prespecifying a primary outcome or adjusting for multiple tests can address different aspects of this issue. The registry record does not report a multiplicity strategy, an adjustment method, or whether any secondary analyses were designated exploratory. It is therefore not possible to determine how multiple outcomes were considered in the reported analysis.
The registry does not report missing-data counts or methods. It does not state whether participants missed an assessment, whether any crossover period was incomplete, or how unavailable measurements were handled. The number enrolled should not be treated as the number analyzed for every outcome without those details.
The analysis population is also not reported in the registry record. There is no description of whether analyses included all randomized participants, only participants completing both conditions, or another defined group. These gaps limit assessment of how representative the analyzed data are of the randomized study population and how robust any estimate would be to missing observations.
12. 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 Versus Sham Treatment | 0 | 5 | 0.0% |
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 Versus Sham Treatment | 0 of 5 |
Under the registry’s group label Active Versus Sham Treatment, the serious-event figures list 5 at risk and 0 affected. The figures for other adverse events list 5 at risk and 0 affected. These are the counts recorded for the group; the record does not define the risk period or clarify how the at-risk counts relate to participants across the two treatment periods.
The zero affected counts mean that no affected cases are recorded in those fields. They should not be interpreted as proof that no events occurred outside the registry’s specified reporting categories, observation period, or data collection. The record lists no serious event terms. The deaths value is not reported in the registry record.
In general, adverse-event counts are descriptive. Their interpretation depends on the event definitions, collection procedures, follow-up period, and denominator. Those details are not reported. The figures also do not provide a comparative estimate or an uncertainty interval for a difference between active and sham treatment. They should therefore be read narrowly as the recorded counts, not as a complete characterization of safety.
13. What the Result Does, and Does Not, Mean
The record establishes that a randomized, double-masked crossover study of active and sham rTMS was completed and that its primary outcome concerned change in PET asymmetry after active treatment. It identifies secondary outcomes related to psychomotor vigilance and tinnitus ratings. It does not include numerical outcome results, so the magnitude, direction, and precision of the observed findings are not available from the registry record.
The study design can frame a comparison, but the design label alone does not reveal what that comparison found. A crossover structure may support within-participant comparisons in general, yet assessing the validity of such a comparison requires information about treatment order, completion of both periods, period effects, and the analysis model. These details are not reported in the registry record.
The registry’s completed status does not establish a benefit, a lack of benefit, or a particular safety profile. The listed adverse-event counts are limited registry entries and are not accompanied by enough information about definitions, observation, or analysis to support a broader safety conclusion. The brief summary describes the intended population, but the record does not provide individual participant characteristics or outcome data that would establish how broadly any result applies.
In general, a treatment effect is interpreted using an estimate and its uncertainty, along with the study design and outcome definition. Since the primary and secondary numerical results are absent, there is no basis in this record for estimating a treatment contrast or judging its precision. The record documents the research question and design, but does not show whether the measured imaging outcome or symptom outcomes differed between active and sham conditions.
14. Why This Trial Matters Statistically
This trial is statistically notable for combining a randomized, double-masked design with a crossover comparison and an imaging-based primary outcome. That combination raises clear methodological questions: how repeated measurements were modeled, how the treatment periods were handled, and how the imaging measure relates to the symptom outcomes. The registry identifies the design and outcomes, but does not report the analysis details needed to answer those questions.
The recorded enrollment is 5, while the brief description refers to up to twenty (20) intended subjects. This contrast is relevant when considering how much information the study could contribute, but the registry does not report outcome estimates or their precision. It is therefore not possible to quantify the uncertainty of the primary comparison or determine whether the data were adequate for a particular inference.
The record also illustrates why outcome definitions and outcome results are different kinds of information. Naming a PET asymmetry measure tells readers what investigators intended to assess; it does not show the observed change or establish that the measure tracks tinnitus symptoms. The secondary outcomes provide additional questions, but their numerical findings are not reported either.
Finally, planning calculations and observed findings must be kept distinct. The record describes planning assumptions based on a fraction of an observed effect, but the effect and resulting planning values are absent. Those illustrations cannot stand in for outcome estimates, and they are not observed power. Statistically, the most important contribution available from this record is the documented design and measurement framework, alongside substantial limits on interpretation caused by the absence of numerical results and analysis details.
15. 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 main limitation for interpreting this study is that the registry record does not report numerical results for the primary or secondary outcomes. Without estimates and measures of uncertainty, readers cannot assess the magnitude, direction, or precision of the outcome comparisons. The record also does not report p-values or confidence intervals.
Although the study is identified as a crossover trial, details that affect analysis are absent. The record does not describe treatment order, the randomization procedure, the masking procedures, completion of both periods, or how time and possible carryover were handled. It does not report the model used to account for repeated observations or the analysis population.
The brief summary describes intended participant characteristics and planned clinical evaluation, but individual characteristics of enrolled participants are not reported. The record does not state how many participants contributed data to each outcome or how missing observations were handled. The recorded enrollment should not be assumed to be the analysis count for every measure.
The primary endpoint is described as change in a PET asymmetry index, but the record does not give the calculation details, baseline values, or numerical follow-up findings. It also does not report how the imaging outcome was expected to relate to symptom outcomes. The relationship between the primary measure and the secondary outcomes therefore cannot be assessed from the registry record.
Safety interpretation is limited by the absence of event definitions, collection details, and a stated observation period. The registry reports counts, but not a comparative analysis or the context needed to interpret those counts beyond their recorded categories. Taken together, these limitations mean the record documents the study framework more fully than its statistical findings.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Using PET-CT to Target and Validate Low-frequency TMS as Treatment for Tinnitus — NCT00329524.
- Registry record last updated 2015-05-04; status last verified 2015-04.
- Results first posted 2009-08-07.
- 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.
19. Record Summary
The University of Arkansas sponsored this completed randomized, double-masked crossover study of repetitive transcranial magnetic stimulation for tinnitus. The registry records enrollment of 5 and describes active and sham treatment separated by a one-week interval. The brief description outlines an intended population with tinnitus severe enough to seek medical attention.
The primary endpoint is change in PET asymmetry index, expressed as a ratio and summarized as a mean with standard deviation. Secondary outcomes include psychomotor vigilance and the difference in Visual Analog Rating of Tinnitus following active and sham treatment. Numerical results for these outcomes are not reported in the registry record.
The record lists 5 at risk and 0 affected for both serious and other adverse-event figures under the Active Versus Sham Treatment label. The deaths value is not reported in the registry record. Statistical analysis details, missing-data methods, and the analysis population are also not reported.