This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Patch Test of Benzalkonium Chloride Disinfectant Spray (NCT01762982), a randomized na study. The primary outcome is Proportion of Participants With Skin Irritation Scores at 24 Hours.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01762982 |
| Phase | NA |
| Condition | Wound Healing |
| Allocation | Randomized |
| Design model | Single Group |
| Masking | Single |
| Enrollment | 36 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with normal skin who received study treatments at baseline. The primary outcome description defines its analysis population as participants who received treatment and had at least one post-baseline skin irritation assessment. The registry record does not report further eligibility details or participant characteristics.
Intervention
The test treatment was benzalkonium chloride disinfectant spray at 0.13%. The intervention listing calls it “0.13% Benzalkonium Chloride”; the arm description specifies benzalkonium chloride (0.13%) disinfectant spray water.
Comparator
The listed controls were sodium lauryl sulfate (SLS) water solution at 0.3% w/w as the positive control, normal saline water at 0.9% w/v as a negative control, and an empty Finn Chamber as another negative control. The registry record does not explain how participants were assigned across these treatments or whether each participant received more than one treatment.
Primary question
The primary question was whether skin irritation was observed at 24 hours following product application, measured as the proportion of participants in the specified categories of a dermatologist-assessed skin irritation scale. The registry record gives criteria for considering a product non-irritant, but does not report the observed scores or proportions needed to assess those criteria.
3. Trial Design
The registry record describes a completed, randomized, single-centre, examiner-blind human patch test. Its official title refers to a patch test of Bactroban disinfectant liquid on normal skin, while the study title refers to a benzalkonium chloride disinfectant spray. The intervention and arm descriptions identify the test product as benzalkonium chloride at 0.13%. The record does not explain the difference in wording between the titles and the intervention description.
The record lists an enrollment of 36 and classifies the study model as single group. It also lists randomized allocation and four treatment descriptions: the test product, an SLS positive control, saline negative control, and an empty Finn Chamber negative control. The model label and the presence of several treatment descriptions do not, on their own, establish how treatment was administered. The allocation procedure, the number of participants assigned to each treatment, and whether individuals received multiple treatments are not reported in the registry record.
The study start and primary completion are both recorded as 2012-02, and the overall status is completed. The registry record lists skin irritation assessments at 24, 48, and 72 hours among the secondary outcomes. The primary outcome is skin irritation at 24 hours, from baseline to 24 hours following application. It describes a trained dermatologist assessing the skin reaction. The record does not report details such as the application procedure, the timing of assessments relative to one another, or how the examiner’s blinding was maintained.
The study is identified as phase NA and lists wound healing as its condition. Its stated aim is to evaluate the irritation potential of benzalkonium chloride disinfectant spray when it contacts normal human skin. No broader clinical treatment question or comparison of clinical outcomes is described 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.
Before assignment: Of 37 participants screened, 1 did not meet the study criteria. Remaining 36 were randomized to the study. Two negative controls, one positive control and one test product were used simultaneously and inserted into the patch (Finn chamber patch test device) as it was a 4-way split plot design study.
Overall Study
| Stage | Overall |
|---|---|
| STARTED | 36 |
| Received Saline Water | 36 |
| Received Benzalkonium Chloride | 36 |
| Received SLS | 36 |
| Received Empty Finn Chamber | 36 |
| COMPLETED | 36 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Intention to Treat (ITT) population: All randomized participants who received the study treatments at baseline and had at least one post baseline skin irritation scoring assessment.
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.
| Characteristic | Unit | All Randomized Participants |
|---|---|---|
| Participants analysed | 36 | |
| Age, Continuous | Years | 36.2 (SD 12.27) |
| Sex: Female, Male: Female | Participants | 22 |
| Sex: Female, Male: Male | Participants | 14 |
6. Primary Endpoint
The registry lists the primary outcome as Proportion of Participants With Skin Irritation Scores at 24 Hours, measured over Baseline to 24 hours following product application.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the proportion of participants with skin irritation scores at 24 hours following product application. It uses a dermatologist-assessed ordinal scale: 0 means no visible reaction; 1, weak erythema (redness); 2, erythema, infiltration, and papule; 3, erythema, edema, papule, and blister; and 4, erythema, edema, and extreme blistering. The endpoint is intended to describe how often reactions of differing recorded severity occur, rather than to measure a continuous quantity such as reaction size.
The registry record gives a specific rule for judging a product non-irritant to skin: the proportion with score 2 should not be more than 1 out of 15 participants, and there should be no cases of score 3 or 4. These criteria make the category definitions relevant to interpretation; a single overall percentage without the category details would not establish whether the rule was met.
Using proportions can make the frequency of reactions in the assessed group easier to interpret than reporting scores alone. However, the record does not report the observed category counts or proportions at 24 hours. It therefore does not show whether the stated non-irritant criteria were met. The primary outcome population is defined as participants who received treatments at baseline and had at least one post-baseline skin irritation scoring assessment; the record does not report how many participants met that definition.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the question, assessment scale, and decision criteria, but it does not provide the primary outcome results. In particular, no observed proportion for any irritation score at 24 hours is reported. Without those results, the recorded criteria cannot be applied to determine whether the test product met the stated definition of non-irritant to skin. The trial’s completed status does not substitute for the missing outcome findings.
The endpoint is categorical and includes more than one possible reaction level. A result expressed only as a combined proportion of participants with “irritation” would require a clear definition of which scores count as irritation. The record’s explicit criteria focus on score 2 and on whether any score 3 or 4 occurred, so category-specific information matters. The listed score descriptions indicate progressively different observed reaction features, but the record does not say that the categories were combined for analysis.
The comparator descriptions provide context for the intended assessment: SLS is identified as a positive control, while saline and the empty Finn Chamber are identified as negative controls. The record does not report their observed scores or proportions either. Consequently, it is not possible from the registry results to evaluate the test product’s reaction pattern relative to any of these controls. Nor does the record report a numerical contrast, confidence interval, or significance test for the primary endpoint.
The available population information also limits interpretation. The enrollment is recorded as 36, but the primary outcome population requires receipt of treatment and at least one post-baseline assessment. The number meeting that definition, the amount of missing outcome information, and the treatment-specific denominators are not reported in the registry record. Enrollment alone therefore cannot be treated as the denominator for every endpoint or treatment.
In general, proportions describe the frequency of an outcome in the group being assessed. Their precision depends on the number of observations and the number of observed events; a confidence interval, when reported, conveys uncertainty around an estimated proportion. No primary endpoint estimate or interval is reported in the registry record, so its magnitude and precision cannot be assessed. Any sample-size planning illustration based on an observed effect should be understood as a planning calculation, not as evidence of observed power or a replacement for outcome estimates.
Overall, the record supports a description of the study’s design and intended endpoint, but not a conclusion about the observed irritation response. The score definitions and non-irritant rule are available; the results needed to apply them are not reported in the registry record.
9. Statistical Methods Explained
What does the proportion measure?
The endpoint is described as a percentage of participants, with the outcome defined by skin irritation scores at 24 hours. In general, a proportion is the number of people meeting a stated outcome divided by the number assessed for that outcome. A percentage expresses that proportion on a scale of 100. The registry record does not give the observed numerator or denominator for each score, so no result can be reconstructed from the enrollment figure alone. The endpoint definition also makes clear that score categories should be considered: the non-irritant rule refers separately to score 2 and to the occurrence of scores 3 or 4.
Why do the score categories matter?
The scale is ordinal: its categories have a stated order, but the labels describe different kinds of visible reaction rather than equal increments on a numerical measurement. General statistical practice treats ordinal categories with care. Averaging category labels can imply that the gap between adjacent scores has a consistent quantitative meaning, which is not established by the category descriptions. Reporting the distribution across categories can retain information that a single average or combined percentage would conceal. In this trial, the stated decision rule specifically depends on the frequency of score 2 and the absence of scores 3 or 4.
What would a confidence interval add?
In general, a confidence interval describes uncertainty around an estimated quantity, such as a proportion. A narrow interval indicates greater statistical precision than a wide interval, while neither width nor location alone establishes clinical importance. For a proportion, precision is influenced by how many observations contribute and how many events occur. The registry record does not report a confidence interval for the primary endpoint, nor does it report the category counts needed to calculate one. No precision claim about the observed irritation proportions can therefore be made from the record.
How should the design labels be read?
Randomized allocation indicates that the record labels the study as randomized, and single masking indicates one level of masking. The official title further calls the test examiner-blind. These labels describe aspects of design, but do not reveal the allocation sequence, implementation, or who was unaware of treatment assignment beyond the examiner wording. The record also labels the model single group while listing a test treatment and controls. In general, design labels should be interpreted alongside the actual assignment and assessment procedures; those procedures are not reported in the registry record.
The controls have stated roles: SLS is the positive control, and saline and the empty Finn Chamber are negative controls. In general, a positive control can help establish whether an assessment detects a known response under study conditions, while a negative control can help characterize responses in the absence of the test ingredient or in the chamber alone. These are general purposes, not evidence that either control behaved as expected in this trial. The registry record does not report their observed results.
What can be inferred from the analysis description?
The registry record lists 6 outcome measures and 3 analyses. It also indicates that the primary outcome has several categories or time points and is not reduced to one comparison. This means the record does not provide a single numerical treatment contrast for interpretation. The precise statistical model, any adjustment for covariates, and the handling of repeated observations are not reported in the registry record. It would be inappropriate to infer a particular method from the study’s design labels or outcome wording.
In general, when outcomes are assessed at multiple times, analyses need to clarify whether each time is treated separately, whether within-person dependence is accounted for, and which comparisons are intended. If categories are analyzed as categorical outcomes, the analysis should also specify whether categories are kept separate or combined. These choices affect what an estimate means and how uncertainty should be interpreted. The available record names assessment times and outcome categories but does not specify these analytical details.
Why can over-dispersion matter?
Over-dispersion is a general issue in count or proportion models when the observed variability is greater than a model assumes. If it is ignored, standard errors can be too small and confidence intervals or significance tests can appear more precise than warranted. Whether over-dispersion is relevant depends on the model and data structure. The registry record does not report a model for which this issue can be assessed, and it does not report the outcome data needed to evaluate variability. It should not be assumed that a particular correction was used.
What do planning calculations mean?
General sample-size calculations describe the amount of information a future study might need under stated assumptions. The planning illustration associated with this record is described as using the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For non-time-to-event outcomes, such illustrations are expressed as participants per arm for 80% power or another stated power level. They are planning illustrations, not an estimate of the power achieved in the completed study. The registry record does not report a trial-specific sample-size justification or the underlying observed effect needed to assess such planning assumptions.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary outcome at 24 hours and secondary skin irritation outcomes at 24, 48, and 72 hours. It also indicates 6 outcome measures and 3 analyses, while noting that the primary outcome involves several categories or time points and is not reduced to one comparison. This leaves the analysis family and the intended primary contrast unclear. The statistical plan for handling multiple outcomes, time points, categories, or comparisons is not reported in the registry record.
In general, examining multiple outcomes or comparisons can increase the chance of finding an apparently notable result by chance. Methods for addressing multiplicity depend on which tests are confirmatory and how they relate to one another. The record does not specify whether any adjustment was planned or used. Because the observed results and comparison structure are not reported, the practical effect of multiplicity cannot be evaluated.
The primary outcome population is defined as randomized participants who received study treatments at baseline and had at least one post-baseline irritation assessment. This is an eligibility definition for the analysis population, not a report of how many participants were analyzed. The number assessed at each time, treatment-specific denominators, missing scores, and reasons for missingness are not reported in the registry record. The record does not describe imputation or another missing-data method.
In general, missing outcomes can affect interpretation if the likelihood of missingness is related to participants’ reactions or other characteristics. A complete-case analysis may be less representative when missingness is informative. Without the missing-data counts and analysis approach, it is not possible to assess this concern for the study. The registry record also does not report whether analyses followed an intention-to-treat principle beyond its stated population definition.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Overall Study | 0 | 36 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Overall Study | 3 of 36 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Overall Study |
|---|---|---|
| Pruritus | Skin and subcutaneous tissue disorders | 3 of 36 |
The registry record reports serious adverse events for the overall study: 0 affected among 36 participants at risk. It reports other adverse events for the overall study: 3 affected among 36 participants at risk. These are counts of participants affected as recorded in the safety summary; they are not measures of the primary skin irritation endpoint, which has its own score definitions and assessment times.
The record lists no serious adverse event terms. The deaths field is null, so deaths are not reported in the registry record. A zero in the serious adverse event count means no affected participants were recorded in that field; it does not establish that every possible adverse effect was absent. Similarly, the other adverse event count does not by itself identify the event types, their severity, timing, relationship to treatment, or distribution across treatment groups. Those details are not reported in the registry record.
The safety figures are presented for the overall study rather than separately for the test product and each control. The record does not report treatment-specific safety denominators or comparisons. These figures should therefore be read as a limited overall summary, not as a comparative estimate of safety between the listed treatments.
12. What the Result Does, and Does Not, Mean
The study’s stated purpose was to evaluate the irritation potential of benzalkonium chloride disinfectant spray on normal human skin. It used a dermatologist-assessed scale and specified a non-irritant rule based on score 2 and the absence of scores 3 or 4. Those details define what the investigators intended to assess and how the recorded categories relate to their stated criterion.
However, the primary endpoint results are not reported in the registry record. No observed proportion by irritation score, treatment-specific result, or comparison with the positive and negative controls is available. It is therefore not possible to determine from this record whether the non-irritant rule was met, how often each reaction category occurred, or how the test product’s results compared with the controls.
Even if outcome estimates were available, a proportion from a human patch test would describe the assessed participants and conditions. General statistical interpretation distinguishes a study estimate from a universal statement about all people or all circumstances. Precision would depend on the data and would be better understood with uncertainty intervals and clear denominators. The registry record does not report the primary endpoint estimates, interval estimates, or treatment-specific analysis populations.
The record also does not establish a clinical effect on wound healing. Wound healing is listed as a condition, but the stated study aim and primary endpoint concern skin irritation after product application to normal skin. The available information does not support conclusions beyond that specified assessment question. The completed status indicates that the study is recorded as completed, but it does not provide the missing outcome findings.
Accordingly, the defensible interpretation is limited: the registry documents a randomized, examiner-blind patch-test design, its treatments, assessment scale, and criterion, but not the observed primary results. No conclusion about the observed irritation response or comparative treatment effects can be drawn from the outcome information in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable for the gap between a clearly described decision rule and the absence of the outcome data needed to apply it. The record defines score categories and states that score 2 should not occur in more than 1 out of 15 participants, with no score 3 or 4 cases, for a product to be deemed non-irritant. Yet the proportions and category counts are not reported. A threshold is useful only when the corresponding observations and denominators are available for evaluation.
The endpoint also illustrates why categorical outcomes should not be reduced casually to a single number. A summary that combines reaction categories could obscure the distinction between a mild response and the score levels explicitly addressed by the criterion. Statistical reporting should preserve the category information needed to answer the study question and make the analysis population clear.
The design labels invite another useful lesson: a registry can identify randomization, masking, and a study model without documenting enough operational detail to reconstruct treatment assignment or analysis. Here, the single-group model label appears alongside several treatment descriptions. Without an account of how participants received those treatments, the intended comparison structure cannot be determined from the record alone.
Finally, enrollment and completion status are not substitutes for endpoint reporting. They do not reveal the analyzed denominators, the distribution of outcomes, or the precision of an estimate. This record therefore highlights the statistical value of reporting category-specific results, denominators, missingness, and the planned comparison structure alongside a stated criterion.
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 principal limitation is that the registry record does not report the observed primary endpoint scores or proportions. As a result, the stated non-irritant criterion cannot be evaluated, and no primary estimate or its precision can be described. Results for the listed controls are also not reported, so the test product cannot be compared with them using the registry information.
The treatment assignment structure is unclear. Randomized allocation is recorded, but the study model is labeled single group and the record lists a test treatment plus three controls. The allocation procedure, group sizes, and whether participants received one or multiple treatments are not reported in the registry record. This limits assessment of the intended comparisons and of dependence between observations if multiple treatments or times were assessed within participants.
The primary outcome population is defined by treatment receipt and at least one post-baseline assessment, but the number meeting that definition is not reported. Treatment-specific denominators, missing assessments, and reasons for missingness are also not reported. Without these details, the completeness and representativeness of the analyzed observations cannot be evaluated.
The registry record does not report the statistical model, handling of the ordinal categories, multiplicity approach, confidence intervals, or a trial-specific sample-size justification. It also does not give participant characteristics or detailed application and assessment procedures. These omissions constrain evaluation of precision, analytical choices, and generalizability. The study’s single-centre designation and normal-skin focus further describe its setting and target context, but the record does not provide enough information to assess how results might vary in other settings or populations.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Patch Test of Benzalkonium Chloride Disinfectant Spray — NCT01762982.
- Registry record last updated 2014-01-22; status last verified 2013-07.
- Results first posted 2014-01-22.
- 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.
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18. Record Summary
NCT01762982 is recorded as a completed, randomized, single-centre, examiner-blind human patch test with enrollment of 36. Its stated aim was to assess irritation potential on normal human skin. The test treatment was benzalkonium chloride disinfectant spray at 0.13%; listed controls were SLS solution at 0.3% w/w, normal saline at 0.9% w/v, and an empty Finn Chamber.
The primary outcome was the proportion of participants with skin irritation scores at 24 hours. The registry record defines scores from 0 through 4 and gives criteria for deeming a product non-irritant. It also lists assessment times at 24, 48, and 72 hours. The observed primary scores and proportions, treatment-specific results, analysis denominators, and statistical methods are not reported in the registry record. Overall safety reporting lists 0 serious adverse events and 3 other adverse events among 36 participants at risk.