Intranasal Capsaicin Treatment for Non-Allergic Irritant Rhinitis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Intranasal Capsaicin Treatment for Non-Allergic Irritant Rhinitis (NCT02493257), a randomized phase 2 study. The primary outcome is Change in Total Symptom Score.

2. Clinical Question

3. Trial Design

This was a randomized, prospective, parallel-group phase 2 trial with quadruple masking. Its official title describes a double-blinded randomized prospective trial, while the registry classifies masking as quadruple. The registry does not specify which roles were masked, how masking was maintained, or how allocation was generated or concealed. The sponsor was The University of Texas Health Science Center, Houston.

The registry lists an enrollment of 22 and records 11 participants in each arm for the primary outcome. One arm received intranasal capsaicin and the other received vehicle solution. The vehicle is described as 100 μL of 1% ethanol in 0.9% saline solution. The arm description states that 5 consecutive intranasal applications of capsaicin or placebo were to be given, with 1 hour between applications. The capsaicin preparation description is incomplete in the registry record, so the full preparation and administration details cannot be established from that description.

The study start is recorded as 2014-10, and primary completion is recorded as 2019-08-02. The registry status is Completed. The study’s stated purpose was to investigate intranasal capsaicin treatment in people with nonallergic irritant rhinitis and to evaluate optical rhinometry as a way to quantify symptomatic improvement during and after treatment. The posted primary outcome is change in Total Symptom Score at baseline and 4 weeks. The registry record does not report a detailed protocol, the allocation ratio, the randomization procedure, or the planned statistical analysis.

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 Change in Total Symptom Score, measured over baseline and 4 weeks.

The primary endpoint was change in Total Symptom Score, measured at baseline and 4 weeks. The score uses a visual analog scale to rate sneezing, nasal irritation, nasal obstruction, and nasal congestion. Each symptom is rated from 0, meaning no distress, to 10, meaning agonizing or unbearable distress. The four ratings are summed, giving a total score from 0 to 40, with higher scores representing greater symptom distress.

A combined symptom score can provide a concise summary of several symptoms relevant to nonallergic rhinitis. The registry says this rating system is commonly used and recommended by the FDA for clinical trials on nonallergic rhinitis. That rationale explains the choice of symptom measure in the record; it does not establish that the score captures every aspect of the condition or that a particular change is important to patients.

The posted endpoint is expressed as a median change with an inter-quartile range for each arm. The registry does not define the sign convention for change or report the individual symptom components separately. Consequently, the direction of a change should be interpreted with care: a negative value indicates a lower follow-up score only if change was calculated as follow-up minus baseline, and that convention is not stated in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, parallel-group trial and posts a median change with an inter-quartile range for the primary outcome in each arm. Understanding these summaries requires separating descriptive statistics from comparative inference. The record identifies the endpoint timing and the arm summaries, but does not report the test or model used to compare the groups.

What does the median describe?

The median is the central value when observed scores are ordered. It is less influenced by unusually high or low values than the mean, which can be useful when outcomes are skewed or when a small sample makes extreme observations influential. A median is nevertheless a summary, not a display of every participant’s change. Distinct distributions can have the same median, and a median alone does not reveal the shape of the observations or how many values lie near it.

The registry identifies the outcome parameter as a median and the dispersion as an inter-quartile range. The reported capsaicin summary is -5, with an inter-quartile range from -12 to -2; the vehicle summary is 2, with an inter-quartile range from -4 to 3. An inter-quartile range describes the spread of the central portion of observed values. It is not a standard error and is not a confidence interval. It communicates variability among observed changes, rather than the precision of a population-level treatment contrast.

What would a confidence interval add?

In general, a confidence interval expresses the uncertainty around an estimated quantity under a specified statistical method. For a randomized comparison, an interval around the between-arm effect would help readers assess which comparative effects remain compatible with the data and method. It is distinct from the inter-quartile range: one describes uncertainty in an estimate, while the other describes the distribution of observations. The registry record does not report a confidence interval for a between-arm effect on the primary endpoint.

A p-value, when reported, addresses how compatible the data are with a specified null hypothesis under the assumptions of a test. It does not measure the size or clinical importance of an effect. No primary-endpoint p-value or test result is reported in the registry record. It is therefore not appropriate to infer statistical significance from the medians or from the inter-quartile ranges alone.

Why does the change definition matter?

A change score depends on the order of subtraction. If it is calculated as follow-up minus baseline, negative values represent lower scores at follow-up; if the order is reversed, the interpretation reverses. The registry specifies that the outcome is change from baseline and gives the measurement timeframe as baseline and 4 weeks, but does not state the subtraction convention. The total score’s scale direction is clear: higher scores represent more distress. The change direction is not fully interpretable without knowing how the subtraction was defined.

In general, analyzing change scores is one way to compare outcomes measured at more than one time. Other approaches can model follow-up scores while accounting for baseline values. The choice can affect the estimate and its precision, depending on the data and assumptions. The statistical approach used for this endpoint is not reported in the registry record, so it cannot be determined whether the posted medians came from the trial’s primary analysis method or how a baseline-adjusted comparison was handled.

Why are arm summaries not the same as a randomized contrast?

Randomization assigns participants to intervention groups by chance according to a study procedure. The trial is classified as randomized, but the registry record does not provide the sequence-generation or allocation-concealment details. A direct comparison should estimate the difference between groups using an identified method and should report uncertainty around that estimate. Two separate arm summaries do not, by themselves, supply that contrast. In particular, the distance between medians must not be calculated and presented as though it were the trial’s reported effect estimate.

In general, small studies can yield imprecise estimates, and observed results can be sensitive to the values of individual participants. This is a statistical consideration, not a claim about what happened in this trial. The posted arm counts are 11 for capsaicin and 11 for vehicle. The registry does not report a confidence interval for the comparative effect, and the arm summaries alone do not show how much uncertainty surrounds a treatment contrast.

What should be inferred from the design labels?

The parallel model means the registry classifies participants as assigned to separate intervention arms rather than describing a crossover arrangement. The masking field is recorded as quadruple, and the official title uses the phrase double-blinded. The record does not identify which participant, investigator, assessor, or other roles were masked, nor does it explain the difference between the title wording and the masking classification. These labels describe the registry’s design entries; they do not give enough information to assess masking success.

In general, masking can reduce the influence of expectations on reporting, care, or assessment, but its protection depends on implementation and outcome measurement. Because the primary outcome is a symptom rating, how participants and assessors were masked may be relevant to interpreting it. The registry does not report whether masking was assessed or whether it remained intact.

What can the planning assumptions tell readers?

The registry’s general planning illustration is described as based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that a future study will produce the same result. The record does not provide the numerical planning outputs in the registry record for this analysis, so no participant target or power figure can be stated. It also does not report the trial’s own sample-size justification.

Overall, the posted summaries are useful for describing the observed arm-level changes, while the missing comparative estimate, uncertainty measure, sign convention, and analysis details limit inferential interpretation. General statistical concepts help explain these distinctions, but they cannot substitute for analysis details absent from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 4 outcome measures and indicates that no secondary outcomes are posted. It identifies change in Total Symptom Score as the primary outcome. The study’s stated purpose also mentions optical rhinometry, but the registry does not provide a posted secondary result for that measure. The other outcome details and their relationship to the stated primary question are not reported in the registry record.

Multiplicity arises when a study conducts several statistical tests or evaluates multiple outcomes, time points, or subgroups. In general, testing many hypotheses can increase the chance of at least one result appearing notable by chance. Approaches to multiplicity can include prioritizing a primary endpoint, adjusting inference, or clearly labeling analyses as exploratory. The registry record does not report a multiplicity strategy, a hierarchy of outcomes beyond identifying the primary outcome, or details of any secondary analyses. No adjustment should therefore be assumed.

Missing-data handling is also important because outcome summaries may depend on which participants had measurements at each time. The primary outcome summaries list 11 participants in each arm, but the registry record does not describe whether any measurements were missing, how missing values were handled, or whether all randomized participants were included in the analysis. The record does not identify an intention-to-treat, per-protocol, or other analysis population. The posted arm counts should not be used to infer these unreported analysis details.

The registry records 0 analyses. That entry does not provide a statistical plan or explain how the posted primary summaries were generated. The planned analysis method, any sensitivity analyses, and any interim analyses are not reported in the registry record. These omissions limit the ability to assess whether the posted results correspond to prespecified analyses or how robust they are to missing data and analytic choices.

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 reports no serious adverse events in either arm. For intranasal capsaicin, 0 serious events are recorded among 11 participants at risk; for vehicle solution, 0 serious events are recorded among 11 participants at risk. The registry also records 0 other adverse events among 11 participants at risk in each arm, and 0 deaths in each arm. No serious adverse event terms are listed.

These entries describe what the registry records for the groups and event categories. A zero count means that no events were reported in that category in the posted results; it does not establish that an event could not occur or that all possible harms were excluded. The record does not provide definitions for serious or other adverse events, details of safety surveillance, the duration of safety follow-up, or information about event attribution. Those details are not reported in the registry record.

Safety interpretation should also account for the scope of the posted data. The trial’s enrollment is recorded as 22, and the adverse-event groups list 11 participants at risk in each arm. A record of zero events in these groups is a descriptive finding, not a precise estimate of risk in a wider population. The registry’s event counts do not support a conclusion about comparative safety beyond the events recorded in this trial.

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

The registry reports a median Total Symptom Score change of -5 for intranasal capsaicin, with an inter-quartile range from -12 to -2. For vehicle solution, it reports a median change of 2, with an inter-quartile range from -4 to 3. The endpoint was measured at baseline and 4 weeks, and each arm’s posted summary includes 11 participants. These are the central observed changes and their reported spread within each arm.

The results do not, on their own, establish a causal or statistically precise difference between the randomized groups. The registry does not report a comparative effect estimate, a confidence interval for that estimate, or a p-value for the primary outcome. The medians cannot be substituted for a formal randomized contrast, and the inter-quartile ranges are not confidence intervals. The change sign convention is also not stated, which constrains directional interpretation.

The study record describes the rationale for assessing symptom change and optical rhinometry, but the posted primary result addresses the symptom score. No secondary results are posted in the registry record. The reported outcome therefore does not show whether optical rhinometry tracked symptom change or whether other outcomes differed between groups.

These findings should be understood as registry-reported descriptive summaries from a completed phase 2 trial, not as a complete account of the trial’s statistical evidence. Important information—including the analysis method, missing-data handling, analysis population, and detailed participant characteristics—is not reported in the registry record. A small study can be informative about the observed data while still leaving considerable uncertainty about the size and reproducibility of a comparative effect. The record supports describing the posted numbers, but not a broader conclusion about treatment efficacy or clinical importance.

13. Why This Trial Matters Statistically

This trial is statistically notable for the contrast between a randomized design and the limited form of the posted primary results. Randomization is intended to support comparisons between assigned groups, while the registry reports a median and inter-quartile range separately for each arm. Those summaries describe the observed changes, but they do not replace an estimate of the randomized between-arm contrast or its uncertainty.

The endpoint also illustrates why scale definitions and change conventions matter. The Total Symptom Score combines four symptom ratings, each on a 0-to-10 visual analog scale, into a total ranging from 0 to 40. The scale direction is described, but the subtraction order for the change score is not. Without that convention, even the direction of a change requires a qualification. Clear reporting of the calculation would make the numerical summaries easier to interpret.

The study’s stated aim included evaluating optical rhinometry as a way to quantify symptomatic improvement. Yet no secondary results are posted in the registry record. This leaves an important part of the study’s stated measurement question unanswered by the available results. It also illustrates why registering an outcome or objective is not the same as reporting its findings.

For biostatisticians and clinical researchers, the record highlights the importance of reporting the analysis population, missing-data approach, comparison method, and uncertainty around estimates. Those details allow readers to distinguish descriptive summaries from inferential results and to judge whether the stated design question has been answered. Their absence does not change the numbers that are posted, but it narrows what can responsibly be concluded from them.

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 registry record contains limited information for evaluating this trial’s methods and results. It does not report detailed eligibility criteria, participant characteristics, the diagnostic process, or the setting in which participants were recruited. The external applicability of the results therefore cannot be assessed from the record alone.

The capsaicin arm description is truncated, so its full preparation and administration details are not available. The vehicle is described as 100 μL of 1% ethanol in 0.9% saline solution, and the record states that 5 consecutive applications were to be administered with 1 hour between applications. The record does not provide a complete account of adherence, deviations from the intended administration, or the timing of outcome assessment relative to treatment beyond the baseline and 4 weeks timeframe.

The primary outcome is a symptom score, but the registry does not report the individual symptom results, baseline and follow-up distributions, or the sign convention for change. It posts medians and inter-quartile ranges by arm, without a reported comparative estimate, confidence interval, or p-value. The analysis method, missing-data approach, and analysis population are not reported in the registry record.

The registry identifies the study as randomized and quadruple-masked, but does not explain sequence generation, allocation concealment, which roles were masked, or whether masking was assessed. It also does not report protocol deviations, reasons for withdrawal, or the handling of participants with incomplete measurements. These gaps prevent a full assessment of potential bias and result robustness. The record’s completed status does not resolve these limitations in the available reporting.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Intranasal Capsaicin Treatment for Non-Allergic Irritant Rhinitis — NCT02493257.
• Registry record last updated 2020-08-17; status last verified 2020-07.
• Results first posted 2020-08-17.
• 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

NCT02493257 is a completed randomized, parallel-group phase 2 trial of intranasal capsaicin versus vehicle solution for nonallergic irritant rhinitis. The registry classifies the study as quadruple-masked. The sponsor was The University of Texas Health Science Center, Houston; the recorded start was 2014-10, and primary completion was 2019-08-02.

The primary outcome was change in Total Symptom Score at baseline and 4 weeks. The registry reports a median change of -5, with an inter-quartile range from -12 to -2, for capsaicin, and a median change of 2, with an inter-quartile range from -4 to 3, for vehicle solution. Each arm’s posted primary summary includes 11 participants. The record does not report a formal between-arm estimate or its uncertainty.

No serious adverse events, other adverse events, or deaths are recorded in either arm. The analysis method, missing-data handling, and analysis populations are not reported in the registry record. No secondary results are posted.