Safety and Efficacy Study of TNX-201 Capsules for Treatment of Single Tension-Type Headache: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy Study of TNX-201 Capsules for Treatment of Single Tension-Type Headache (NCT02423408), a randomized phase 2 study. The primary outcome is Number of Subjects Pain Free.

2. Clinical Question

The clinical question concerns short-term response after treatment of one qualifying headache, rather than repeated treatment or prevention. The registry describes a randomized, parallel-group comparison, with placebo as the comparator. Random assignment is intended to make the groups comparable on average, while masking is intended to limit the influence of treatment knowledge on care and outcome assessment. The record lists quadruple masking but does not specify which roles were masked.

The primary endpoint is a count of participants meeting a pain-free definition at the specified assessment time. The endpoint description defines pain free as an NRS score of 0 and as a VAS score <= 5. It also identifies a binary yes/no question as an assessment method, but does not state its response rule. The registry record does not provide the observed counts by treatment group, an effect estimate, or a statistical test. Therefore the clinical question is identifiable, but its answer cannot be inferred from the posted results described in the record.

3. Trial Design

The registry identifies this as a phase 2, randomized, multicenter, double-blind, placebo-controlled, parallel-group study. The official title describes it as a proof-of-concept study. The listed enrollment is 165. The study status is completed, with the start listed as 2015-06 and primary completion listed as 2016-02.

Participants were assigned to TNX-201 or placebo according to the intervention descriptions. TNX-201 was posted as four 35 mg capsules, and the placebo arm received four placebo capsules. Both were to be taken when a qualifying tension-type headache occurred. The brief summary describes a single 140 mg dose of TNX-201. The record identifies the masking as quadruple, but does not identify the masked roles or describe how masking was maintained.

A parallel-group design compares the assigned groups over the study period rather than having each participant receive both study treatments. Randomization can reduce systematic differences between groups at assignment, but the registry record does not report the allocation procedure or whether allocation was concealed. It also does not report group sizes at randomization, a protocol-level analysis plan, or details of the participating centers.

The primary endpoint is the number of participants pain free at 2 hours after dosing. Listed secondary outcomes include pain-free assessments at other times, use of rescue medication during the 24-hour post-dose period, and improvement in VAS severity category at 2 hours. These additional outcomes involve more than one time point or outcome definition. The record does not report results for these outcomes or describe how they were incorporated into a statistical testing strategy.

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

Analysis population for the primary outcome, as defined in the registry: LOCF Analysis 8 subjects in the TNX-201 group and 10 subjects in the placebo group who did not take a dose during the double-blind treatment period and/or did not report data 2-hour post-dose were excluded from analyses.

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 Number of Subjects Pain Free, measured over 2 hours.

The primary endpoint counts participants who were pain free 2 hours after dosing. Pain was assessed using a 4-point NRS, a VAS, and a binary yes/no question. On the NRS, grades range from 0, none, to 3, severe; the registry defines pain free as a score of 0. On the VAS, anchored from No Pain at 0 to Worst Imaginable Headache Pain at 100, pain free is defined as a score <= 5. The record does not give the response rule for classifying a participant as pain free from the binary yes/no question.

A pain-free count is a binary outcome summarized as the number of participants who meet the endpoint definition, rather than a measurement of average pain intensity. It can be clinically interpretable as a count of participants who reached a specified state at the assessment time. The definition and assessment method matter: different instruments or thresholds can classify responses differently, and the registry lists more than one assessment method.

The registry record does not report the pain-free counts by group, a between-group estimate, or a confidence interval. It therefore does not establish the size or precision of any treatment contrast for this endpoint. The outcome description also notes that participants who did not take a dose during the double-blind treatment period and/or did not report data 2-hour post-dose were excluded from analyses. The effects of these exclusions on the endpoint comparison cannot be assessed from the record alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study uses a randomized parallel-group comparison, with TNX-201 and placebo as the two interventions. In general, randomization assigns participants by chance and is intended to reduce systematic differences between groups at the start of a trial. It does not guarantee identical groups, particularly for characteristics that occur infrequently. The registry record identifies randomization but does not describe the sequence generation or allocation concealment procedures.

What does a binary endpoint count?

The primary outcome is expressed as a number of participants who are pain free at the specified assessment. This is a binary endpoint at the participant level: each person either meets the definition or does not. Counts are commonly interpreted alongside the number of participants assessed in each group. A comparison can then estimate how the outcome differs between assigned groups. The registry record gives neither the primary counts nor a comparative estimate, so no such comparison can be interpreted.

The endpoint definition uses multiple assessments. The NRS definition classifies a score of 0 as pain free, and the VAS definition classifies scores <= 5 as pain free. The record also names a binary yes/no question, without stating its decision rule. In general, an outcome definition should specify which measurement determines classification, especially when multiple instruments are listed. The record does not explain how the three assessment approaches were combined or whether they were analyzed separately.

How should uncertainty be understood?

In general, a confidence interval describes the uncertainty around an estimated effect under the chosen statistical model and assumptions. A narrow interval indicates greater precision than a wide interval, while an interval that includes no difference may be compatible with both little or no difference and effects in either direction, depending on the measure used. A p-value addresses compatibility between data and a specified null hypothesis under a statistical model; it does not measure the size or clinical importance of an effect. Neither a confidence interval nor a p-value for the primary comparison is reported in the registry record.

For binary outcomes, statistical methods may model the probability of an event or compare counts between groups. The choice of effect measure and model affects interpretation. The record does not identify a method for estimating the primary treatment contrast, state an adjustment strategy, or describe the assumptions used for inference. These details are not reported in the registry record, so it is not possible to assess whether any particular model was used or whether its assumptions were checked.

Why do multiple outcomes matter?

The primary and secondary outcome descriptions include several assessment times and types of measurement. In general, testing many outcomes or time points can increase the chance of obtaining at least one apparently notable result by chance if each is tested separately. A multiplicity plan can define which comparisons are confirmatory and whether or how statistical thresholds are adjusted. The registry record does not report such a plan or any analysis results. The listed outcomes therefore should not be treated as a set of statistically confirmed findings.

General statistical interpretation also distinguishes a planned sample-size calculation from observed evidence. A planning illustration estimates the sample size needed under specified assumptions; it is not a measure of the probability that an observed result is true, and it is not observed power. The registry record notes that any sample-size illustrations are based on an observed effect and are not the trial's own design calculation. It does not report the original sample-size justification. No numerical planning estimates are needed to interpret the primary endpoint, for which no group comparison is reported.

What do the missing-data notes establish?

The primary outcome description labels the analysis as LOCF, or last observation carried forward. In general, this approach uses a participant's last recorded measurement as a substitute for a later missing measurement. Such substitution relies on assumptions about what the unobserved measurement would have been; those assumptions may not hold in every setting. The registry record does not detail how LOCF was applied or explain its implications for the endpoint results.

The same description says that 8 participants in the TNX-201 group and 10 participants in the placebo group who did not take a dose during the double-blind treatment period and/or did not report 2-hour post-dose data were excluded from analyses. This specifies an exclusion condition but does not provide a complete participant flow or the number included in the primary outcome analysis. The record also does not report sensitivity analyses that might assess how missing or excluded data affect interpretation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple secondary outcomes, including pain-free status at several post-dose times, rescue medication use during the 24-hour post-dose period, and VAS severity-category improvement at 2 hours. The primary outcome description also names three assessment approaches. In general, examining multiple outcomes and times can raise a multiplicity issue: without a prespecified strategy, isolated findings may be difficult to distinguish from chance variation. The registry record does not report a multiplicity adjustment, hierarchy, or testing strategy.

The primary endpoint is labeled as a LOCF analysis. The record also states that participants who did not take a dose during the double-blind treatment period and/or did not report data 2-hour post-dose were excluded. It does not explain how these statements relate in practice, how LOCF was applied, or whether any other missing-data procedures were used. General interpretation of LOCF depends on assumptions about the unobserved outcome, which cannot be checked from the posted description.

The registry does not report a full analysis population definition, participant flow by outcome, or sensitivity analyses for missing data. It also does not report an intention-to-treat analysis or another named primary analysis population. These details are not reported in the registry record. With no reported analysis results, it is not possible to assess the consequences of exclusions or missing observations for the estimated treatment contrast.

11. Safety Results

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

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 safety summary lists 0 serious adverse events among 78 participants at risk in the TNX-201 group and 0 among 73 participants at risk in the placebo group. It also lists other adverse events affecting 5 participants in the TNX-201 group and 6 in the placebo group. These are counts, not adjusted comparisons, and the registry record does not report a statistical test or uncertainty interval for them.

The record does not identify the specific other adverse events, their severity, timing, duration, or relationship to study treatment. It also does not report deaths; the death fields are not populated with a count. That should not be interpreted as evidence that no deaths occurred. The list of serious adverse-event terms is empty, so specific serious-event terms are not reported in the registry record.

These figures describe events recorded in the listed safety groups. They do not, by themselves, establish whether an event was caused by treatment or provide a complete assessment of safety. Differences in the counts should not be treated as a comparative effect without the fuller event definitions, follow-up information, and analysis.

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

The registry record establishes that a completed phase 2 randomized comparison was designed to evaluate a single dose of TNX-201 for one qualifying tension-type headache. It also establishes the stated primary endpoint: the number of participants pain free at 2 hours after dosing, assessed with named pain measures. These details clarify the question the trial was intended to address.

The record does not report the primary outcome counts, an effect estimate, confidence interval, or statistical test. As a result, the posted information does not establish whether pain-free outcomes differed between the TNX-201 and placebo groups, how large any difference might have been, or how precisely it was estimated. The absence of a reported result is not evidence of no effect, just as the study's completed status is not evidence of a particular effect.

The adverse-event summary gives limited descriptive information: no serious adverse events are listed in either group, while other adverse events are recorded for participants in both groups. These counts do not establish causation or provide detail about the events. The record does not report deaths or a complete safety analysis.

Any interpretation should also account for the endpoint's multiple assessment methods and the stated exclusions for participants without a dose or 2-hour data. The record does not explain the full analysis procedure or provide sensitivity analyses. In general, statistical evidence depends on both the estimated effect and its uncertainty, along with the design and analysis assumptions. Those elements are not available for the primary comparison in the registry record.

13. Why This Trial Matters Statistically

This trial illustrates an important distinction in clinical-trial reporting: a record can describe a randomized design and prespecified outcomes without reporting the outcome estimates needed to answer the research question. The design information identifies the intended comparison, but it does not itself show what happened in either group.

The primary endpoint also highlights how outcome definition affects analysis. Pain-free status is expressed using NRS and VAS thresholds, while a binary question is also named. Clear rules for combining or separately analyzing these measures are important when results are interpreted. The registry record does not explain that relationship or report the endpoint counts.

The study lists several secondary outcome times and measures. In general, multiple comparisons call for a transparent analysis strategy so readers can distinguish primary evidence from exploratory findings. No such strategy or analysis results are reported in the registry record. The description of exclusions and LOCF also makes the analysis population and missing-data handling important to assess, but the necessary detail is not reported.

For biostatistical interpretation, the central lesson is that design, endpoint definition, analysis methods, and numerical results are all needed. The record gives useful information about the first two, but leaves the primary effect and its precision unavailable. The safety counts add descriptive context, but are not a substitute for a complete safety analysis.

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 limitation for interpreting this trial from the registry record is that no primary outcome comparison is reported. There are no group-specific pain-free counts, effect estimates, confidence intervals, or p-values. The record also lists zero analyses, leaving the reported design without corresponding inferential results.

The endpoint is described using multiple assessment methods, but the record does not state how the NRS, VAS, and binary yes/no assessments were combined or handled in analysis. The threshold is stated for the NRS and VAS, but not for the binary question. This makes the exact operational outcome definition less clear than a single prespecified measure would be.

The record identifies LOCF and exclusions for participants who did not take a dose and/or did not report 2-hour post-dose data. It does not provide a complete participant flow, a full analysis-population definition, or sensitivity analyses. The impact of missing observations and exclusions therefore cannot be evaluated.

The study is described as a proof-of-concept phase 2 trial of a single dose for a single qualifying headache. Results from that setting, if available, would address that specific treatment episode and endpoint; the record does not describe repeated dosing or prevention questions. Eligibility details, the statistical analysis plan, sample-size justification, multiplicity strategy, and detailed adverse-event information are not reported in the registry record. These gaps limit both clinical interpretation and assessment of statistical robustness.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy Study of TNX-201 Capsules for Treatment of Single Tension-Type Headache — NCT02423408.
• Registry record last updated 2017-04-11; status last verified 2016-12.
• Results first posted 2017-02-17.
• 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 describes a completed phase 2, randomized, multicenter, double-blind, placebo-controlled, parallel-group study of TNX-201 for a single qualifying tension-type headache. Listed enrollment is 165. The TNX-201 intervention is four 35 mg capsules, described in the brief summary as a single 140 mg dose; the comparator is four placebo capsules.

The primary endpoint is the number of participants pain free at 2 hours after dosing, assessed using a 4-point NRS, VAS, and binary yes/no question. The record labels the analysis LOCF and notes exclusions for participants who did not take a dose and/or did not report 2-hour post-dose data.

No primary outcome comparison or statistical analysis results are reported. The safety summary lists no serious adverse events in either group and records other adverse events affecting 5 participants in the TNX-201 group and 6 in the placebo group. Further event details and death information are not reported in the registry record.