Trental for the Treatment of Vertigo/Dizziness/Imbalance: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Trental for the Treatment of Vertigo/Dizziness/Imbalance (NCT02592863), a randomized na study. The primary outcome is Effect of Trental Treatment Using the Dizziness Handicap Inventory, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale.

2. Clinical Question

The study asked whether 12 weeks of Trental (pentoxifylline), taken 3 times per day, affected dizziness-related outcomes compared with placebo taken on the same schedule. The registry describes patients with reported dizziness and identifies imbalance secondary to insufficient microvascular perfusion as the condition of interest. Its summary frames the question around symptoms attributed to vestibular dysfunction and the possibility of increasing blood flow to the inner ear. Those statements describe the study rationale, not a result of the trial.

The primary outcome entry names the DHI, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale. The registry’s description explains the DHI, but outcome values and a single comparison across these measures are not reported in the registry record. The clinical question is therefore identifiable, while the answer cannot be assessed from posted outcome estimates.

3. Trial Design

The registry describes a randomized, double-blind, parallel-group trial with pentoxifylline and placebo arms. Randomization means assignment is intended to use chance rather than investigator choice; double masking means the record identifies masking at two levels, but does not state who was masked or how masking was maintained. A parallel design assigns participants to a study arm rather than having each participant receive both treatments in sequence. These are design labels in the registry, not evidence about how fully the design was implemented.

The intervention descriptions specify Trental (pentoxifylline) 3 times per day for 12 weeks and placebo 3 times per day for 12 weeks. The registry lists enrollment of 26. It identifies the sponsor as University of Missouri-Columbia, gives a start date of 2015-01, and lists primary completion as 2020-12-31. The overall status is TERMINATED. The reason for termination, actual treatment duration for participants, and the number who completed follow-up are not reported in the registry record. The listed dates alone do not establish why the trial ended or how much data were collected.

The phase entry is NA. The registry record does not report details of the allocation sequence, concealment, masking procedures, treatment adherence, eligibility criteria, recruitment flow, or the planned statistical analysis. Nor does it report a sample-size justification from the trial’s own design. The record includes planning assumptions for an illustration based on an observed effect; these assumptions should not be mistaken for the rationale used to plan or conduct this trial. Such distinctions matter because design labels describe broad features, while operational details determine how those features were carried out.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Determine the effect of 12 weeks of Trental compared to Placebo in patients with reported dizziness on the Dizziness Handicap Inventory

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: We only evaluated patients that completed the study

6. Primary Endpoint

The registry lists the primary outcome as Effect of Trental Treatment Using the Dizziness Handicap Inventory, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale, measured over 12 weeks.

The primary outcome entry concerns change in dizziness-related measures after 12 weeks. It names the Dizziness Handicap Inventory, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale. The registry describes the DHI as a self-report questionnaire with 25 questions about the effect of dizziness on daily life. Questions are grouped into physical, emotional, and functional domains. Responses are “Always,” “Sometimes,” or “No,” scored as 4, 2, or 0 points respectively. The total ranges from 0 to 100 points; a higher score indicates a more severe handicap.

A patient-reported measure is useful for capturing perceived limitations that may not be represented by a clinical observation alone. The DHI focuses on how dizziness affects daily functioning and well-being. The registry identifies a mean as the outcome parameter and standard deviation as the dispersion measure, which is a common way to describe a continuous score across participants. That description specifies the intended summary, not the actual outcome values: the means, standard deviations, and comparisons are not reported in the registry record.

The primary outcome title names three instruments, but the record does not reduce their categories or time points to one comparison. It also does not provide comparable descriptions of the Vestibular Activities and Participation measure or the European Evaluation of Vertigo Scale. Their scoring, direction, and interpretation are therefore not reported in the registry record. Without the posted outcome values and a defined comparison, the endpoint’s intended subject is clear but its observed effect cannot be interpreted.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the trial as randomized, double-blind, and parallel-group. General explanation: random allocation is intended to make treatment assignment independent of participants’ measured and unmeasured characteristics, on average. It does not guarantee that two small groups will have identical baseline characteristics. The record does not describe the randomization sequence or allocation concealment, so the methods used to implement randomization are not reported in the registry record. Likewise, the double-masking label does not specify which participants, clinicians, or outcome assessors were masked. A parallel design compares groups assigned to different arms; it is not a crossover comparison in which each participant receives both assignments.

The primary outcome is described as a mean of a continuous measure, with standard deviation as the dispersion statistic. General explanation: a mean summarizes the average score in a group, while a standard deviation describes how spread out individual scores are around that average. A between-arm difference in means can express the average separation between groups, but interpretation depends on the score scale, analysis population, and uncertainty around the estimate. No arm means, standard deviations, or treatment contrast are reported in the registry record, so none can be interpreted for this trial.

General explanation: a confidence interval gives a range of effect values that are reasonably compatible with the observed data under the specified model and procedure. Its width reflects precision; a wider interval indicates less precision than a narrower interval on the same scale. A p-value measures how incompatible data are with a specified null hypothesis under model assumptions; it is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. Neither confidence intervals nor p-values for the primary outcome are reported in the registry record.

The outcome title includes three measures, and the registry notes that the primary outcome has several categories or time points rather than one reduced comparison. General explanation: when multiple outcomes, domains, time points, or statistical tests are considered, the chance of at least one apparently unusual result can increase if each is judged separately without a prespecified strategy. A statistical plan can identify a primary contrast, specify how secondary outcomes will be handled, and describe any adjustment for multiple testing. The plan and any multiplicity adjustment are not reported in the registry record. The record therefore does not establish which comparison would carry the primary inferential claim.

The sample-size illustration is described as using an observed effect, a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It is explicitly a planning illustration, not the trial’s own design calculation. General explanation: a planning calculation asks how much information a future study might need under stated assumptions about the effect and variability. Its answer depends on those assumptions and does not tell how likely this completed or terminated trial was to find an effect. Such a calculation is not “observed power,” and it does not replace an estimate of the effect and its confidence interval. No trial-specific sample-size justification or numerical effect estimate is reported in the registry record.

The record reports zero outcome analyses. It does not state whether an analysis was planned using change from baseline, an end-of-treatment score, an adjusted model, or an unadjusted comparison. General explanation: adjustment for baseline values can improve precision in some settings, while an unadjusted comparison may be easier to interpret; the choice should be prespecified and suited to the design and outcome. Neither approach can be attributed to this trial from the registry information. The analysis population—such as all randomized participants or only those with complete measurements—is also not reported in the registry record.

General explanation: missing data can affect both the number of participants contributing to an estimate and the validity of the comparison, especially if the likelihood of missingness is related to treatment or outcome. Analysts may describe the amount and pattern of missing data and state assumptions or methods used to address it. Here, withdrawals, missing outcome measurements, and imputation methods are not reported in the registry record. The enrollment figure and safety denominators do not resolve those questions for the primary outcome.

Finally, the outcome scale is continuous, while the safety entries are event counts. General explanation: continuous outcomes are often described with means and measures of spread, whereas event counts or proportions require methods appropriate to discrete events and the relevant observation period. Over-dispersion is a concern in count models when variability exceeds what a chosen model assumes; it cannot be assessed from zero event counts alone. The registry does not report a statistical method for either the primary outcome or safety comparisons.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome entry names the DHI, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale, and the registry notes multiple categories or time points rather than a single reduced comparison. The number of outcome measures is listed as 3. When several outcomes or time points are evaluated, general statistical practice is to define the main comparison in advance and explain how other comparisons will be interpreted. Otherwise, selective emphasis or multiple testing can make a result appear more conclusive than the full set of analyses warrants. The registry record does not report a multiplicity strategy, an adjustment, or a prespecified hierarchy among the listed measures.

The record lists zero analyses. It does not report an analysis population, participant flow, withdrawals, outcome completion, or missing-data handling. These omissions prevent assessment of whether all randomized participants were included, whether outcome data were available for both arms, or whether missingness could have influenced a comparison. The enrollment figure of 26 is not enough to establish the number analyzed for any outcome.

The adverse-event denominators are specific to the safety entries and should not be treated as primary-outcome denominators. No details about missing outcome data, exclusions, adherence-based analyses, or imputation are reported in the registry record. There is also no posted statistical analysis plan in the record. Consequently, the intended primary comparison, treatment of secondary measures, and assumptions used for incomplete data remain unclear. These are limits on interpretation, not evidence that a particular method was or was not used outside what the registry reports.

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.

The registry lists two safety groups. For pentoxifylline, 7 participants are recorded as at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. For placebo, 13 participants are recorded as at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. No serious adverse-event terms are listed. These entries describe the posted counts and their listed denominators; they do not provide a comparative statistical analysis.

Zero recorded events in these groups should be read narrowly. It means that the registry’s displayed counts contain no events in the categories recorded, not that the treatment arms have been shown to have identical safety or that risk has been ruled out. The reason that the safety denominators differ from the enrollment figure, the duration of safety observation, event definitions, collection procedures, and follow-up completeness are not reported in the registry record. The record also does not explain whether all participants were observed for the same period.

General explanation: an event count is easier to interpret when its denominator, observation window, and event-ascertainment method are clear. With no events recorded, the data do not reveal how common an event might be in a broader population, and small or incomplete groups can leave substantial uncertainty. The posted safety figures therefore describe recorded events only; they do not establish comparative safety.

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

The record establishes that a randomized, double-blind, placebo-controlled, parallel-group trial was registered to examine pentoxifylline for imbalance and dizziness-related outcomes. It specifies a 12-week treatment schedule and identifies the DHI, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale in the primary outcome title. It also records enrollment of 26, a TERMINATED status, and the listed safety counts. These registry entries characterize the study and what the registry contains.

The record does not report the primary outcome scores, between-arm estimates, confidence intervals, p-values, or analyses. It therefore cannot show whether scores favored either arm, how large any difference was, or how precise an estimate might be. The DHI’s scoring description explains how a score is intended to represent handicap, but does not supply observed scores. The registry’s note that several categories or time points were not reduced to a single comparison further limits a concise interpretation of the primary outcome.

General explanation: statistical significance and clinical importance are different questions. A small estimated difference can be precise, and a larger estimate can be uncertain; a p-value alone does not describe the magnitude or practical relevance of an effect. In this record, neither the effect estimate nor inferential statistics are reported, so neither question can be addressed. The absence of posted analyses should not be converted into a claim that the trial found no effect.

The zero event counts are also limited to the safety groups and categories recorded. They do not demonstrate equivalence between arms or establish an absence of risk. The reason for termination, completion status of participants, missing outcome data, and analysis populations are not reported in the registry record. Those gaps make it impossible to determine how much evidence the trial contributed to its clinical question.

The appropriate conclusion is descriptive: the registry records the design and intended outcomes, but does not report results adequate to estimate the treatment effect. Any stronger conclusion would require information not present in the registry record.

13. Why This Trial Matters Statistically

This trial illustrates an important distinction between a study’s registered question and the evidence needed to answer it. The registry provides a clear broad comparison—pentoxifylline versus placebo—and identifies patient-reported dizziness-related outcomes. Yet a design description alone cannot show what happened to participants’ scores. Without outcome estimates and uncertainty, readers cannot judge the direction, magnitude, or precision of a treatment contrast.

The case also shows why endpoint definition matters. The primary outcome title names three measures, while the record notes multiple categories or time points and does not reduce them to one comparison. When outcomes have several domains or assessment times, readers need to know which contrast is primary and how the remaining results are treated. That clarity is essential for understanding what a statistical test addresses and how to account for multiple comparisons. The relevant analysis details are not reported in the registry record.

Registry status and enrollment counts also cannot stand in for participant flow or completed analyses. A TERMINATED status and enrollment of 26 do not reveal why the trial ended, how many participants completed follow-up, or how many contributed outcome data. The safety denominators do not answer those questions for efficacy outcomes. Reporting analysis populations, missingness, and outcome estimates would allow readers to evaluate precision and potential bias.

Finally, the posted zero adverse-event counts demonstrate why event counts need context. Denominators are listed, but observation time and ascertainment details are not. For statistical interpretation, transparency about both positive findings and the limits of captured data is valuable. Here, the meaningful statistical point is not a conclusion about treatment efficacy; it is that the registry record does not contain the analysis needed to assess it.

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 main trial-specific limitation is the lack of posted outcome results. Although the primary outcome is described as a mean with standard deviation at 12 weeks, the registry does not report score summaries, treatment contrasts, confidence intervals, or p-values. The primary outcome entry also combines three named measures and indicates that several categories or time points were not reduced to one comparison. The values and scoring details for two of those measures are not reported in the registry record.

The registry lists enrollment of 26 and status TERMINATED, but does not state the reason for termination or provide participant flow. Completion, withdrawal, adherence, and the number contributing to each outcome are not reported in the registry record. The primary outcome analysis population and handling of missing data are also not reported. As a result, the available enrollment figure cannot establish the amount of outcome information or the representativeness of the analyzed group.

Several design and analysis details that would aid appraisal are absent: the randomization procedure, allocation concealment, who was masked, and the statistical analysis plan. The registry reports zero analyses, so no prespecified or completed analysis can be assessed from this record. The sample-size assumptions describe a planning illustration based on an observed effect, not the trial’s own design justification. No numerical planning result or trial-specific rationale is reported in the registry record.

The safety entries show zero events in listed groups, but do not report observation duration, event definitions, or collection procedures. The difference between the enrollment figure and safety risk sets is not explained. Together, these limitations mean the record supports a description of intended design and recorded safety counts, but not a robust estimate of efficacy or comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Trental for the Treatment of Vertigo/Dizziness/Imbalance — NCT02592863.
• Registry record last updated 2024-10-15; status last verified 2024-10.
• Results first posted 2024-10-15.
• 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

The registry record describes NCT02592863, “Trental for the Treatment of Vertigo/Dizziness/Imbalance,” as a randomized, double-blind, parallel-group placebo-controlled trial sponsored by University of Missouri-Columbia. It lists enrollment of 26, a start date of 2015-01, primary completion on 2020-12-31, and status TERMINATED. Pentoxifylline and placebo were each described as taken 3 times per day for 12 weeks.

The primary outcome entry names the DHI, Vestibular Activities and Participation, and European Evaluation of Vertigo Scale, with a 12-week timeframe. The DHI description explains its 25 questions and 0 to 100 score range, with higher scores indicating greater handicap. Outcome estimates and analyses are not reported in the registry record; the record lists zero analyses.

Safety entries list 7 participants at risk in the pentoxifylline group and 13 in the placebo group, with zero serious adverse events, other adverse events, and deaths in both groups. Reasons for termination, participant flow, missing data, and analysis populations are not reported in the registry record.