Neurobiological Similarities of Tinnitus and PTSD: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Neurobiological Similarities of Tinnitus and PTSD (NCT05981391), a registered phase not stated study. The primary outcome is Resting-State Functional MRI.

2. Clinical Question

The clinical rationale described in the registry is that PTSD-related distress may be associated with increased attention to tinnitus and greater perceived loudness or discomfort. The study seeks to characterize symptoms and brain activity in people with these conditions, including people who have both. Its focus is measurement and characterization; the listed procedures do not constitute a treatment trial.

The group structure allows the research question to be considered across different combinations of tinnitus and PTSD status. However, without reported outcome values and analysis results, it is not possible to describe whether the groups differed in resting-state activity, how large any differences were, or how precisely they were estimated. The stated aim should therefore be distinguished from a finding: the registry describes what the investigators intended to assess, not a reported answer to the comparison question.

3. Trial Design

The registry record identifies NCT05981391, titled “Neurobiological Similarities of Tinnitus and PTSD,” with The University of Texas Health Science Center at San Antonio as sponsor. Its status is COMPLETED. The recorded study start is 2021-02-04, and the primary completion date is 2024-11-01. Enrollment is listed as 64.

Participants are described in four groups defined by condition status: Tinnitus and PTSD, Tinnitus Only, PTSD Only, and Healthy Controls. Each group description refers to active duty service members and/or veterans. The record does not describe assignment to a treatment, and allocation is not stated. The groups are condition-defined rather than randomized arms, so differences between them would not by themselves establish that either condition caused a difference in the fMRI measure.

The listed procedures are diagnostic tests or assessments: resting-state functional MRI, the Clinician Administered PTSD Scale for the DSM-5, tympanometry, tinnitus assessment, otoscopy, pure tone air and bone-conduction testing, speech testing, and loudness discomfort assessment. They support characterization of brain activity and clinical or hearing-related status. No therapeutic intervention is listed.

The registry identifies one outcome measure and one analysis. The primary outcome is titled Resting-State Functional MRI, is expressed in Z-Score units, and is described as a mean with standard deviation as its dispersion measure. Its timeframe is “30 minutes of acquired data.” The outcome description refers to BOLD fMRI collected in an unstimulated state and assessment of activation within the Auditory Vigilance Network. The statistical plan, including the specific group-comparison model and any adjustment strategy, is not reported in the registry record.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Resting-State Functional MRI, measured over 30 minutes of acquired data.

The primary endpoint is a mean Z-score derived from resting-state functional MRI. The registry describes acquisition of BOLD images while participants are in an unstimulated state, with an extended time series of 300 whole-brain volumes over ~ 30 min. The activity of interest is within regions of the Auditory Vigilance Network. The stated timeframe is 30 minutes of acquired data.

The registry explains that BOLD levels were transformed to Z-scores. In general, a Z-score expresses a value in standard-deviation units relative to a reference distribution. The record states that a Z-score of 0 represents the population mean and that positive points represent values above that mean; positive scores are described as representing more brain activation within the reported regions. These statements explain the intended scale, not the observed score for any participant or group.

A resting-state measure is used to characterize activity without a task stimulus, which can be relevant when the research question concerns patterns of brain activity in an unstimulated state. The registry describes ongoing processing checks and control for white matter, cerebral spinal fluid, and movement. It does not report the actual mean Z-scores, standard deviations, region-specific estimates, or any group contrasts. Consequently, the endpoint definition is available, but the magnitude and precision of the measured results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous outcome summarized by a mean and standard deviation. In general, a mean describes the center of a set of measurements, while a standard deviation describes their spread around that center. These are descriptive summaries. They do not, on their own, show whether group means differ beyond what might be expected from sampling variability. For that, an analysis and an uncertainty measure such as a confidence interval would be needed. The group summaries and inferential results are not reported in the registry record.

What does the Z-score represent?

In general, standardization expresses an observation relative to a reference mean and standard deviation. A Z-score of 0 is identified in the registry as the population mean. A positive Z-score is described as activity above that mean, with each positive point representing one standard deviation above the population mean. This explanation helps interpret the scale, but the record does not state the observed scores for the study groups or report the details needed to independently evaluate the standardization reference.

The endpoint description concerns BOLD activity measured using resting-state fMRI. The acquisition is described as 300 whole-brain volumes over ~ 30 min, with the timeframe also stated as 30 minutes of acquired data. Data processing is described as ongoing to ensure integrity and as controlling for white matter, cerebral spinal fluid, and movement. These are features of the outcome acquisition and processing described in the record. Further processing specifications, quality-control thresholds, and the exact statistical procedure are not reported in the registry record.

How should group comparisons be interpreted?

In general, a group comparison estimates how an outcome differs across groups. When group membership is based on existing conditions rather than randomized assignment, observed differences may reflect both condition status and other differences among the people in each group. Randomization is a design feature that can help balance such factors across assigned groups; this registry record does not describe randomized allocation. The group labels distinguish combinations of tinnitus and PTSD status, and should not be interpreted as assigned treatments.

An adjusted analysis can account for measured factors included in a statistical model, but it cannot automatically remove bias from unmeasured or poorly measured factors. The registry record does not report which factors, if any, were included in the analysis, how the groups were compared, or whether the reported endpoint was adjusted. The analysis details are therefore insufficient to assess model assumptions or the extent to which between-group contrasts account for other characteristics.

What would uncertainty estimates add?

In general, a confidence interval gives a range of estimates compatible with the data under the assumptions of the analysis. Its width conveys precision: a narrower interval indicates greater precision than a wider interval. A test statistic or p-value may address a specified null hypothesis, but does not indicate the size or practical importance of an effect. Interpretation is strongest when estimates and uncertainty are considered together rather than relying on a significance label alone. The registry record does not report confidence intervals, p-values, or test statistics for the primary endpoint.

The group means and standard deviations would describe the observed data, while an estimated contrast and its uncertainty would address how precisely a group difference was measured. Because those results are not reported in the registry record, no assessment of precision, compatibility with a null value, or magnitude is possible. The fact that the endpoint is continuous does not identify which analysis method was used; the method is not reported in the registry record.

What do planning calculations mean?

In general, a sample-size illustration based on an observed effect is a planning exercise. It estimates the number of participants per arm that would be needed under specified assumptions to detect a chosen fraction of that effect at a stated power and significance level. Such an illustration is not the same as the study’s original design justification, and it is not observed power. It should not be read as evidence that the completed study had a particular probability of detecting an effect.

The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. The record also distinguishes participant counts per arm from total event counts in time-to-event settings. These are generic assumptions for planning illustrations and do not establish the actual analysis plan for this study. The observed effect and calculated planning values are not reported in the registry record, and the record does not describe these calculations as the study’s own design rationale.

Why can dispersion matter?

In general, the standard deviation indicates how variable individual measurements are around a group mean. Greater variability can make a mean difference harder to estimate precisely for a given amount of information. If measurements are more variable than an analysis assumes, standard errors and uncertainty estimates may be unreliable. This is one reason that the distribution of continuous outcomes and the analysis assumptions matter. The registry record does not report distributional diagnostics or enough results to evaluate dispersion in this study.

Overall, the record supplies a clear endpoint definition and some acquisition and processing context, but not the numerical outcome summaries or model results needed to reproduce or evaluate the primary analysis. Explanations of means, standard deviations, confidence intervals, Z-scores, and planning calculations are general statistical context; they are not findings from this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and one analysis. That limited listing does not establish whether other exploratory analyses were conducted, whether multiple brain regions were examined, or whether any multiplicity adjustment was planned. The outcome description refers to regions within the Auditory Vigilance Network, but the exact number and handling of region-level tests are not reported in the registry record. The statistical plan, including any prespecified hierarchy of outcomes or adjustment for multiple comparisons, is not reported in the registry record.

Missing-data handling is also not described. The record does not report whether any participants lacked usable fMRI data or clinical assessments, how incomplete measurements were handled, or whether participants were excluded from particular analyses. It does not describe imputation, complete-case analysis, or sensitivity analyses. Without this information, the effects of missing or unusable measurements on the estimates cannot be assessed.

The analysis population is not specified beyond the group descriptions and overall enrollment. The record does not report whether all enrolled participants were included in the primary analysis, whether eligibility or data-quality criteria changed the analyzed sample, or how many observations contributed to each group estimate. The population used for analysis is therefore not reported in the registry record.

These omissions do not establish that multiplicity, missingness, or analytic populations were mishandled; they limit what can be evaluated from the registry entry. Assessing the robustness of results would require the analysis plan and outcome reporting, including the numbers analyzed and the handling of incomplete data. Those details are not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists serious adverse events as zero in each of the four groups: Tinnitus and PTSD, Tinnitus Only, PTSD Only, and Healthy Controls. It records other adverse events as 4 for Tinnitus and PTSD, 1 for Tinnitus Only, 2 for PTSD Only, and 0 for Healthy Controls. These are the counts displayed in the safety record; the entry does not provide event descriptions alongside these group figures.

These figures should be read as recorded counts, not as a comparison of risk. The group sizes differ, and the record does not provide the context needed to interpret the events, such as event definitions, timing, severity details for the other events, or whether an event was considered related to a study procedure. The registry also does not report a statistical comparison of adverse-event frequency between groups. No comparative safety conclusion can be drawn from these counts alone.

The absence of recorded serious adverse events in the group entries does not establish that no events occurred outside the registry’s reporting scope or observation period. The record does not describe the safety ascertainment period or provide additional explanatory detail. The counts are best treated as the safety information recorded in the registry, with those limitations in mind.

12. What the Result Does, and Does Not, Mean

The study addresses a question about resting-state fMRI activity in groups defined by tinnitus and PTSD status. The registry describes its rationale, assessment procedures, group definitions, and primary endpoint. These details establish the type of question studied, but they do not answer whether the groups differed. The primary outcome values and results of the stated analysis are not reported in the registry record.

Accordingly, no conclusion about the direction or magnitude of any association between tinnitus or PTSD status and Auditory Vigilance Network activity can be drawn from the posted results. The record also does not show how precisely such an association was estimated. A completed study status is not a substitute for numerical results, and it does not indicate whether an estimate was statistically significant.

Even if group differences were reported, the study’s condition-defined groups and lack of described randomization would matter to interpretation. In general, a comparison among groups with different clinical characteristics may reflect factors beyond the conditions used to define those groups. The registry record does not report the adjustment strategy or details needed to assess those potential influences. Thus, such a comparison would not automatically establish that tinnitus or PTSD caused a change in brain activity.

The registry’s clinical rationale links PTSD-related distress with attention to tinnitus and perceived loudness or discomfort as a motivation for studying both conditions. That proposed relationship should not be treated as an observed result. Although tinnitus assessment and hearing-related procedures are listed, their outcome findings are not reported in the registry record.

The most supportable interpretation is limited but clear: this completed study was designed to characterize resting-state fMRI and related clinical features across groups with different tinnitus and PTSD profiles. The record does not provide the primary endpoint results required to determine what the study found. It therefore supports neither a claim of a difference nor a claim that the groups were alike.

13. Why This Trial Matters Statistically

This study raises a statistical question that is relevant to clinical research: how to compare a continuous brain-activity measure across groups defined by overlapping conditions. Considering groups with tinnitus, PTSD, both, or neither can help frame questions about shared and distinct patterns. The registry record describes that structure and identifies resting-state fMRI as the primary outcome.

The statistical distinction between a study aim and a study result is particularly important. An outcome definition and a biological rationale do not establish an empirical difference. Means, variability, contrasts, and uncertainty estimates are needed to judge the direction, size, and precision of findings. Those numerical results are not reported in the registry record, so the central comparison cannot be evaluated from the posted results.

The study also illustrates why design affects interpretation. Groups defined by existing condition status are not equivalent to randomized treatment groups. Any observed difference would describe an association within the analyzed sample, while causal interpretation would require careful consideration of other group differences and the analysis used. The record does not report enough analytic detail to assess adjustment for potential confounding.

Finally, a continuous neuroimaging endpoint requires clarity about measurement, processing, and analysis. The record gives useful context about the resting-state acquisition, Z-score scale, and processing controls. At the same time, the absence of reported endpoint estimates and analysis details limits reproducibility and assessment of precision. The statistical importance of the record is therefore both in the question it defines and in the distinction between what the registry describes and what its posted results can substantiate.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most direct limitation for interpretation is that the registry record does not report the primary fMRI outcome values or the results of the stated analysis. Without group summaries, estimated contrasts, or uncertainty estimates, the primary question cannot be answered from the posted results. The record also does not report region-specific findings, despite describing assessment of activation within regions of the Auditory Vigilance Network.

The groups are defined by condition status, and allocation is not stated. The record does not describe randomization, so the groups should not be treated as randomized comparisons. It also does not report the analysis model or covariates, limiting assessment of how differences in participant characteristics may have been handled. The group sizes recorded in the safety entry vary, but the numbers contributing to the primary analysis are not reported in the registry record.

There is limited information about measurement and analysis beyond the endpoint description. The record gives acquisition and some processing details, including controls for white matter, cerebral spinal fluid, and movement, but does not report quality-control criteria, the reference used for the Z-score transformation in sufficient detail, or the precise method used to compare groups. It does not report missing-data procedures, analysis-population definitions, or approaches to multiplicity.

The registry’s stated rationale is not itself evidence that PTSD-related distress increases tinnitus attention, loudness, or discomfort in these participants. Findings from those assessments are not reported. Safety-event descriptions and ascertainment details are also absent, which limits interpretation of the counts. These are limitations of the information reported in the registry record; they do not establish that the underlying study lacked procedures addressing these issues.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Neurobiological Similarities of Tinnitus and PTSD — NCT05981391.
• Registry record last updated 2025-07-08; status last verified 2025-07.
• Results first posted 2025-07-08.
• 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.

18. Record Summary

NCT05981391, “Neurobiological Similarities of Tinnitus and PTSD,” is recorded as COMPLETED and sponsored by The University of Texas Health Science Center at San Antonio. The study start date is 2021-02-04, primary completion date is 2024-11-01, and enrollment is 64.

The record describes four condition-defined groups of active duty service members and/or veterans and lists diagnostic and assessment procedures, including resting-state functional MRI and PTSD, tinnitus, and hearing-related assessments. Its primary outcome is a mean resting-state fMRI Z-score for activity in regions of the Auditory Vigilance Network, with a timeframe of 30 minutes of acquired data. The record lists one outcome measure and one analysis.

The primary outcome values and analysis results are not reported in the registry record. Serious adverse-event counts are recorded as zero in each group; other adverse-event counts are also listed by group, without explanatory event details. The statistical plan, missing-data handling, and analysis-population details are not reported in the registry record.