The Effect of Oral Guaifenesin on Pediatric Chronic Rhinitis: A Pilot Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Oral Guaifenesin on Pediatric Chronic Rhinitis: A Pilot Study (NCT01364467), a randomized phase 2 study. The primary outcome is Change in Subjective Nasal Scoring.

2. Clinical Question

The study’s stated aim was to assess relief of nasal symptoms in children with chronic rhinitis. Its summary also describes interest in nasal volume and nasal secretion properties, and lists nasal volume and nasal secretion collection as secondary outcomes. Those measures broaden the study’s assessment beyond reported symptoms, but the primary question concerns the subjective score.

The registry describes this as a phase 2 pilot study. The record does not establish why the study used the design or sample size it did, or how the investigators intended to interpret a pilot result. The posted endpoint and analysis can therefore be read as evidence about the recorded comparison, not as a complete account of the study’s scientific rationale or all of its planned analyses.

3. Trial Design

The registry identifies this as a completed phase 2 randomized, double-masked, parallel-group study sponsored by Virginia Commonwealth University. The two listed interventions are guaifenesin and placebo. In a parallel-group design, participants are assigned to one group and the groups are compared; the registry does not describe participants switching between interventions. The placebo description says it was identical in composition to the treatment except for the active drug.

The study summary describes a 14-day placebo-controlled trial in children ages 7 to 18 years. However, the enrollment field reports 30, whereas the summary describes 36 children. The registry record does not explain this difference, so those figures should not be treated as interchangeable or reconciled by assumption. The record also lists the primary outcome timeframe as baseline to 10 minutes. It does not explain how that short outcome timeframe relates to the stated 14-day study period.

The registry lists the study start as 2011-05, primary completion as 2018-03-05, and status as completed. These dates describe the record’s study timeline; they do not establish how long each participant was followed. The primary outcome is change in subjective nasal scoring. The record also lists nasal volume and nasal secretion collection as secondary outcomes, with three outcome measures and three analyses recorded.

Some design details that would help interpret the comparison are not reported in the registry record. These include the allocation procedure beyond the randomized label, the particular masking arrangements, the planned analysis population, handling of missing measurements, and the statistical plan. The number assigned to each group in the posted outcome data is available, but it should not be used to infer the number originally randomized or the number completing follow-up.

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:

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 Subjective Nasal Scoring, measured over Baseline to 10 Minutes.

The primary endpoint is titled Change in Subjective Nasal Scoring. It uses the Sinus and Nasal Quality of Life Survey, or SN-5, which the registry describes as assessing the impact of infection on nasal symptoms, emotion, and activity. The questionnaire contains five items. Each item is rated from 1, meaning none of the time, through 7, meaning all of the time. The items are averaged into a score ranging from 1, representing better outcomes, to 7, representing worse outcomes.

The endpoint is intended to capture a participant’s reported experience rather than a physical measurement of nasal function. Such a score can represent symptom burden and related effects that may not be fully characterized by a measurement of nasal volume or secretion properties. The registry says scores were used to assess disease severity and the impact of interventions on subjective complaints.

The listed timeframe is baseline to 10 minutes. The record does not clarify the exact timing or circumstances of the follow-up measurement, nor how this timeframe relates to the 14-day treatment period described in the summary. The posted arm values are 0.62 for placebo and 1.53 for guaifenesin, with standard deviations of 0.59 and 1.04, respectively. The registry does not provide a confidence interval or an explicitly stated numerical between-group contrast for this endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary outcome is continuous: it is a score averaged across questionnaire items. A mean summarizes the central value of such measurements, while a standard deviation describes their variability among participants. A mean and standard deviation can give a useful overview, but neither conveys the full distribution of individual scores. In particular, the standard deviation should not be mistaken for a confidence interval or for the uncertainty around the estimated difference between groups.

What does the reported t-test assess?

The registry reports a two-sided t-test comparing the placebo and guaifenesin groups, with p = 0.013. In general, a t-test evaluates whether the observed difference in group means is compatible with a null model in which the population means are equal, subject to the test’s assumptions. A two-sided test considers departures in either direction rather than testing only for a higher or lower score in advance. The p-value is calculated under that model; it is not a measure of the probability that the result is due to chance, nor is it an estimate of effect magnitude.

For a two-group t-test, interpretation depends on features of the data and the chosen test formulation, including the independence of observations and the behavior of the outcome distribution. The registry does not state which variance assumption or test variant was used beyond identifying the analysis as a two-sided t-test. It also does not report diagnostic checks. These details matter because a method’s assumptions affect how its uncertainty and p-value should be understood.

Why is an interval useful?

A confidence interval gives a range of effect estimates compatible with the observed data under a specified statistical procedure. It communicates precision as well as direction. A narrow interval would indicate more precise estimation than a wide interval, although neither alone determines clinical importance. The registry does not report a confidence interval for the primary comparison, and no numerical contrast is stated. Consequently, the p-value does not tell readers how large the group difference was or how precisely it was estimated.

What do the group summaries show?

The placebo group has a reported mean of 0.62 and standard deviation of 0.59; the guaifenesin group has a mean of 1.53 and standard deviation of 1.04. Since higher SN-5 scores correspond to worse outcomes, the summaries describe a higher average score in the guaifenesin group. They do not by themselves explain the cause of the difference. The registry’s outcome title and timeframe indicate a change measure from baseline to 10 minutes, but the record does not give a more detailed definition of the change calculation. The record also does not explain the relationship between that timeframe and the 14-day study duration described in the summary.

What does over-dispersion mean in general?

In general, over-dispersion means that observed variability is greater than a statistical model expects. It is particularly relevant to count outcomes modeled using distributions that assume a prescribed relationship between the mean and variance. When variability is greater than assumed, standard errors may be understated and tests can appear more certain than warranted unless the analysis accounts for that extra variability. The primary endpoint in this record is a continuous questionnaire score, and the registry does not report an over-dispersion assessment or a count model for it. This general concept should therefore not be mistaken for a finding about this trial.

What can be recalculated from the record?

The posted results include group means, standard deviations, and group counts, as well as the sponsor-reported test. However, the registry record does not present a recalculated between-group estimate or its confidence interval. The analysis notes that values are missing or not estimable for a two-arm comparison of this continuous endpoint. Accordingly, no independent numerical contrast should be inferred from the group summaries. The sponsor’s reported test remains the available inferential result in the registry record.

How should planning calculations be read?

Sample-size calculations, when presented, are planning illustrations based on assumptions about the effect to detect, significance level, allocation, and statistical approximation. They are not evidence that a study had a particular probability of detecting an effect after it was conducted. In particular, a planning illustration is not observed power. The registry describes an illustration based on a fraction of the observed effect and equal allocation, but no specific planning sample-size results are stated in the record for this analysis. The study’s actual design justification and sample-size rationale are not reported in the registry record.

The record identifies three outcome measures and three analyses, but it does not describe how the analyses were selected or whether they were prespecified in a statistical analysis plan. It also does not report adjustment for testing multiple outcomes or analyses. These omissions matter because interpreting a single p-value without knowing the wider analysis plan may not reflect the uncertainty associated with all the questions examined. The reported test is therefore best treated as the specific result recorded for the primary outcome, with its precision and broader multiplicity context not fully documented.

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.

R code and output

arm <- c("Placebo", "Guaifenesin")
n   <- c(9, 18)
m   <- c(0.62, 1.53)
sp  <- c(0.59, 1.04)
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  Placebo  9  0.620  0.590  0.166  1.074
CARM  Guaifenesin  18  1.530  1.040  1.013  2.047

11. Analyses Reported by the Sponsor

The registry reports the sponsor’s two-sided t-test for the primary outcome as p = 0.013. It does not report a confidence interval or a numerical between-group estimate. Although group means, standard deviations, and group counts are posted, no independently recalculated contrast is reported for this continuous endpoint. The recorded analysis note says values were missing or not estimable for a two-arm comparison.

There is therefore no second numerical estimate to compare with the sponsor’s test in the registry record. The sponsor’s result is the available inferential comparison, and should not be replaced by a value reconstructed from the group summaries. The record does not provide enough detail to evaluate the test formulation beyond identifying it as a two-sided t-test, or to assess its assumptions and handling of missing data.

The reported p-value addresses compatibility with a null model under the test assumptions; it does not supply the absent effect estimate or confidence interval. Readers should distinguish the sponsor-reported test from any claims about magnitude, precision, or clinical meaning, which are not established by that p-value alone.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and three analyses. It identifies the primary outcome as change in subjective nasal scoring and lists nasal volume and nasal secretion collection as secondary outcomes. However, the statistical plan is not reported in the registry record. The record does not say whether the analyses were prespecified in detail, whether other comparisons were planned, or how the primary and secondary outcomes were prioritized in the analysis.

Multiplicity arises when several hypotheses are tested. In general, as more tests are considered, the chance of at least one apparently notable result can increase if each test is interpreted separately without accounting for the set of tests. Adjustment methods and analysis hierarchies can address that issue, but no multiplicity procedure or testing hierarchy is reported. The p-value for the primary comparison should therefore be read as the reported result for that test, not as a result explicitly adjusted for all outcomes or analyses.

Missing-data handling is also not reported in the registry record. The posted group counts for the primary outcome are 9 for placebo and 18 for guaifenesin, while the enrollment field states 30 and the summary describes 36 children. Those discrepancies do not identify the analysis population or explain why the figures differ. The record does not state how many participants were randomized, whether all randomized participants contributed outcome data, or how unavailable measurements were treated.

The analysis population is not reported in the registry record. It is therefore not possible to determine from the posted description whether the comparison follows an intention-to-treat approach, a per-protocol approach, or another definition. Nor does the record explain whether participants were excluded from the analysis or whether any data were imputed. These omissions limit the assessment of potential bias and the scope of inference from the posted comparison.

13. 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 5% reporting threshold.

The registry reports no serious adverse events in either posted group: 0 among 9 participants at risk in the placebo group and 0 among 18 at risk in the guaifenesin group. It also reports no other adverse events in those same at-risk groups and no deaths in either group. No top serious-event terms are listed.

These figures describe the adverse-event information recorded for the groups and at-risk counts stated in the registry. They do not establish that adverse events could not occur, or that the interventions have equivalent safety profiles. The record does not provide event definitions, collection procedures, follow-up details for safety, or additional context for interpreting the absence of reported events. The discrepancy between the enrollment field and the study summary also remains unresolved; the adverse-event at-risk counts should not be used to reconcile it.

Zero reported events in a limited study can coexist with uncertainty about uncommon events and about how completely events were captured. The registry figures should therefore be read as the reported counts, not as proof of absence of risk or as a broad safety conclusion.

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

The posted result describes a randomized, double-masked comparison of guaifenesin and placebo on a subjective nasal symptom score. The reported mean was 1.53 in the guaifenesin group and 0.62 in the placebo group, with the registry reporting a two-sided t-test p-value of 0.013. Because higher SN-5 scores represent worse outcomes, the group summaries show a higher average score in the guaifenesin group for the recorded endpoint.

That description is not the same as establishing a causal or clinically important effect. A p-value does not measure the size of a difference or the likelihood that an intervention caused it. The registry does not report a confidence interval or a numerical between-group estimate, so the precision and magnitude of the comparison cannot be judged directly from the inferential result. The posted means and standard deviations provide context, but do not replace an explicit contrast and interval.

Several record-level uncertainties also matter. The study summary describes a 14-day trial, while the primary outcome timeframe is baseline to 10 minutes, and the relationship between these descriptions is not explained. The registry’s enrollment field states 30, whereas the summary describes 36 children. The record does not state how missing data were handled, define the analysis population, or report a multiplicity plan. These limitations constrain interpretation of both the primary test and the wider study.

The study summary mentions nasal volume and nasal secretion properties, but those outcome results are not included in the record details available for this analysis. The primary symptom result should not be used to claim a finding for those separate measures. Nor do the reported adverse-event counts establish an absence of risk. The results are best understood as a limited record of a particular group comparison, with unresolved design and analysis details and no basis for medical advice.

15. Why This Trial Matters Statistically

This trial illustrates why interpreting a clinical comparison involves more than reading a p-value. The registry provides group means, standard deviations, group counts, and a two-sided test for a subjective score. Yet it does not provide a confidence interval or a numerical between-group estimate. Without those, the precision and magnitude of the comparison are difficult to assess, even though a p-value is reported.

The record also highlights how the definition and timing of an endpoint shape its interpretation. The SN-5 measures self-reported symptoms and related effects, while the study summary describes a 14-day treatment period and the endpoint is listed as baseline to 10 minutes. The registry does not explain how those details fit together. This makes transparent endpoint specification important: readers need to know what was measured, when it was measured, and how the value was derived.

Other statistical considerations are visible in the record’s limits. It lists three outcome measures and three analyses but does not report a multiplicity plan, missing-data method, or analysis population. Those details influence what a single test can support. The mismatch between the enrollment field and study summary further shows why registry entries should be read as a record with fields that may need clarification, rather than as a fully reconciled account.

As a pilot study, this record can be useful for understanding the kinds of outcomes and comparisons examined. It does not, by itself, answer every question about study planning, statistical assumptions, or the precision of effects. Its statistical value lies partly in showing what was recorded and also which key details remain unreported.

16. 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.

Several limitations are specific to the information recorded for this trial. The enrollment field states 30, while the study summary describes 36 children ages 7 to 18 years. The registry record does not explain the discrepancy. The counts posted for the primary outcome are 9 in the placebo group and 18 in the guaifenesin group, but those figures do not resolve the enrollment difference or show how many participants were originally randomized.

The timing descriptions are also difficult to reconcile. The summary calls the study a 14-day trial, while the primary outcome timeframe is baseline to 10 minutes. The record does not specify the context of the 10-minute measurement or explain its relation to the stated treatment period. The endpoint is titled as a change score, but the registry does not give further detail about how that change was calculated.

For the primary comparison, the registry reports group means, standard deviations, and a two-sided t-test p-value. It does not report a confidence interval or a numerical between-group estimate. It also does not document the t-test variant, assessment of assumptions, missing-data handling, or analysis population. A statistical analysis plan and multiplicity procedure are not reported in the registry record.

The study summary discusses nasal volume and secretion characteristics, but numerical results for those outcomes are not available in the record details used for this interpretation. Safety figures are limited to the reported adverse-event counts, without further information about ascertainment or duration of safety follow-up. These gaps limit conclusions about the broader outcome set, the robustness of the primary analysis, and the scope of the reported safety information.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: The Effect of Oral Guaifenesin on Pediatric Chronic Rhinitis: A Pilot Study — NCT01364467.
• Registry record last updated 2020-04-24; status last verified 2020-04.
• Results first posted 2020-04-24.
• 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.

20. Record Summary

The registry describes a completed phase 2 randomized, double-masked, parallel-group pilot study of oral guaifenesin versus placebo for pediatric chronic rhinitis. Virginia Commonwealth University is listed as the sponsor. The study summary describes a 14-day trial in children ages 7 to 18 years; the enrollment field reports 30, while the summary describes 36 children.

The primary outcome is change in subjective nasal scoring using the SN-5, with a stated timeframe of baseline to 10 minutes. The posted mean scores are 0.62 for placebo and 1.53 for guaifenesin, and the registry reports a two-sided t-test p-value of 0.013. No confidence interval or numerical between-group estimate is reported. The record lists nasal volume and nasal secretion collection as secondary outcomes, but their numerical results are not available for this analysis.

The registry reports no serious adverse events, other adverse events, or deaths in either posted group. The statistical plan, missing-data approach, analysis population, and multiplicity handling are not reported in the registry record.