A Multi-Center, Evaluation of the Onset and Duration of Action of AC-170 0.24% Compared to Vehicle: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Multi-Center, Evaluation of the Onset and Duration of Action of AC-170 0.24% Compared to Vehicle (NCT01881113), a randomized phase 3 study. The primary outcome is Ocular Itching at Duration of Action (8 Hours + 30 Minutes Post-Dose).

2. Clinical Question

The study also addressed onset and duration across several signs of allergic conjunctivitis. Its stated purpose was to evaluate the onset and duration of action of AC-170 0.24% compared with vehicle in preventing signs and symptoms in the conjunctival allergen challenge model. The registered primary endpoint focuses more narrowly on ocular itching at duration of action, rather than combining all signs or all time points into a single endpoint.

The registry record identifies a treatment efficacy challenge performed 8 hours + 30 minutes after drop instillation. It says itching was assessed by the patient and that the average score over both eyes was analyzed. Although the endpoint description gives a measurement scale and assessment timing, it does not report the observed scores or the estimated difference between treatment groups. The clinical question can therefore be described from the registered design, but the comparative answer cannot be determined from the registry record.

3. Trial Design

The registry record identifies NCT01881113 as a Phase 3, randomized, double-masked, vehicle-controlled, parallel study. The official title describes a multi-center evaluation of AC-170 0.24% ophthalmic solution compared with vehicle in the conjunctival allergen challenge model of acute allergic conjunctivitis. Enrollment is listed as 101, and the status is completed. The recorded start is 2013-06 and primary completion is 2013-10.

A parallel design assigns participants to treatment groups that remain separate for the comparison. Randomization is intended, in general, to support comparability between groups by allocating treatment without relying on clinical judgment. Double masking generally means that treatment assignment is concealed from participants and relevant study personnel; the registry record does not provide further details about who was masked or how masking was maintained. These are general descriptions of the design terms, not additional protocol details.

The interventions are AC-170 0.24% and AC-170 0%. The latter is the vehicle comparator identified in the official title. The arm descriptions themselves contain no further details in the registry record. The record does not report the randomization procedure, allocation ratio, or the number randomized to each arm as an enrollment result. Safety risk sets are listed separately and should not be treated as a substitute for a full participant disposition account.

The model uses allergen challenge to assess signs and symptoms of acute allergic conjunctivitis under a defined study setting. The registry record says a treatment efficacy challenge was performed 8 hours + 30 minutes after drop instillation for the primary duration-of-action assessment. It also lists secondary measures of redness, chemosis, and eyelid swelling at onset and duration time points. The detailed challenge procedures, timing beyond the registered descriptions, and operational conduct of the study are not reported in the registry record.

Enrollment is not the same as the number contributing data to every endpoint. The registry record identifies the primary outcome population as Intent to Treat (ITT), but does not report endpoint-specific denominators or participant flow. It also does not report a protocol, a sample-size justification, or further design details that would clarify the planning behind enrollment.

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: There were 101 subjects enrolled, 14 subjects discontinued, and 87 subjects completed the study. Participant flow and baseline characteristics are presented for the 101 subjects that met all inclusion criteria and none of the exclusion criteria and were randomized to receive AC-170 0.24% or Vehicle.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Intent to Treat (ITT)

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 Ocular Itching at Duration of Action (8 Hours + 30 Minutes Post-Dose), measured over 3, 5, 7 minutes post-CAC.

The primary endpoint is ocular itching at duration of action, identified as 8 hours + 30 minutes post-dose. It measures a symptom reported by the participant after a treatment efficacy conjunctival allergen challenge. The registry record states that itching was scored on a scale from 0 to 4, with 0 meaning none and 4 meaning severe. The average of the scores over both eyes was analyzed. The listed time frame for the recorded measure is 3, 5, 7 minutes post-CAC.

Itching is a symptom, while the other registered outcomes include visible or observable signs such as redness, chemosis, and eyelid swelling. Measuring a symptom can complement measures of physical signs because the two kinds of measures describe different aspects of the participant's experience. This is general context; the registry record does not explain the rationale for choosing itching as the primary endpoint or specify how the primary endpoint was selected.

A mean summarizes the average observed score in a group. The standard deviation describes how spread out individual scores are around that mean; it is not a measure of uncertainty in the mean itself. Those are general statistical interpretations of the registered mean and standard-deviation format. The registry record does not provide the group means, standard deviations, treatment contrast, confidence interval, or significance test for this endpoint. Thus, the endpoint's definition is available, but its estimated results and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes the primary outcome as a mean of ocular itching scores, with standard deviation as the measure of dispersion. A mean represents the average of the observations included in an analysis. A standard deviation describes the spread of those observations around their mean. In general, a larger standard deviation indicates greater variability among observed scores, while a smaller one indicates that scores are more clustered. Neither statistic alone tells how precisely the treatment-group difference has been estimated.

The endpoint is recorded on a 0-4 scale, from none to severe, and the average over both eyes was analyzed. The description does not report whether the score was treated as a continuous measure for all statistical purposes, beyond identifying the registered summary parameter as a mean. It does not give details about any transformations, model, covariate adjustment, or handling of repeated observations. Those analytic decisions are not reported in the registry record.

In general, comparing group means can be done with a model or test that estimates a difference and its uncertainty. The appropriate method depends on the study design, outcome distribution, and analysis plan. For a bounded symptom scale, the distribution may have limits or clustering at particular scores; that is a general consideration, not a claim about the observed scores in this trial. The registry record does not provide the score distributions or the statistical procedure used for the primary comparison, so it is not possible to assess whether a particular modeling choice was made or justified.

A confidence interval is a way to express uncertainty around an estimated effect under a specified method. It is useful because it conveys a range of effect estimates compatible with the data and method, rather than presenting only a point estimate. The registry record reports no confidence interval for the primary outcome. It also reports no standard error or other estimate from which the precision of the treatment contrast could be described. No recalculated comparison is available from the posted summary statistics.

Randomization is a design strategy that, in general, aims to make treatment groups comparable with respect to both measured and unmeasured factors at the point of allocation. The registry identifies random allocation and a parallel model, but does not report the allocation sequence method, concealment procedure, or group sizes at randomization. Double masking is registered, but the record does not state which people were masked or whether masking was assessed. These missing details prevent a more specific account of how the design was implemented.

The registry record lists a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. The actual planning illustration values are not reported in the registry record, and the record does not provide the observed primary-outcome effect needed to interpret such illustrations. These planning assumptions do not constitute observed power, and they are not a substitute for a reported sample-size justification. The trial's own sample-size justification is not reported in the registry record.

In general, power is a design concept describing the chance that a planned analysis will identify a specified effect under stated assumptions. A sample-size illustration can explore how the required number of participants changes when assumptions about the effect or analysis change. Such illustrations are conditional on those assumptions; they do not show the probability that a completed trial's result is true, nor do they establish that the study had adequate precision. No numerical sample-size result is available in the registry record for interpretation.

The term over-dispersion is relevant in general when observed variability exceeds what a chosen statistical model assumes. If a model understates variability, standard errors can be too small and uncertainty can appear less than it is. The registry record provides no outcome-level distributional information or model diagnostics, so over-dispersion cannot be assessed for this study. This general point does not imply that over-dispersion occurred.

The record lists 25 outcome measures and no analyses. The primary outcome description indicates several categories or time points, but the registry does not report the test structure, model, contrast selection, or inferential results. Consequently, no statistical estimate can be independently checked against a sponsor analysis, and there are no recalculated results to contrast with a sponsor's own analysis. The sponsor's analysis is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 25 outcome measures, including a primary measure and secondary measures covering redness, chemosis, and eyelid swelling at onset and duration assessments. It also records 0 analyses and notes that the primary outcome has several categories or time points and was not reduced to one comparison. These entries indicate that the outcome set includes multiple measures and assessment occasions, but do not describe how the statistical testing was organized.

In general, testing multiple hypotheses can increase the chance of at least one apparently notable result when each test is interpreted without accounting for the others. Methods for handling multiplicity may define a testing hierarchy, adjust significance thresholds, or identify a limited set of confirmatory comparisons. The registry record does not report whether any such approach was planned or used, and it does not identify a testing sequence or family of hypotheses. No conclusion about multiplicity control can therefore be drawn.

Missing-data methods can also affect interpretation. In general, an analysis may depend on how missing measurements are handled and on assumptions about why they are missing. The primary population is identified as Intent to Treat (ITT), but the registry record does not report the number of participants with missing endpoint data, the reasons for missingness, imputation methods, or sensitivity analyses. It is therefore not possible to assess the completeness of the primary endpoint data or the robustness of the analysis to missing observations.

The record does not explain how the ITT population was operationally defined, whether all randomized participants were included in every endpoint analysis, or whether any additional analysis populations were used. These details, the multiplicity strategy, and the missing-data plan are not reported in the registry record.

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 1% reporting threshold.

Most frequent non-serious adverse event terms

The registry record lists serious adverse events for the AC-170 0.24% group with 51 participants at risk and 0 affected. For the AC-170 0% group, it lists 50 participants at risk and 0 affected. These are counts as entered in the safety record; they are not a comparison adjusted for follow-up or differences in exposure.

For other adverse events, the record lists 3 affected among 51 at risk in the AC-170 0.24% group and 5 affected among 50 at risk in the AC-170 0% group. These figures describe the recorded counts, but the registry record does not define the event category further, state how events were collected, or provide event-specific details. The counts should not be interpreted as a complete account of the types, severity, timing, or duration of events.

The death figures are not reported in the registry record. No statistical safety comparison or confidence interval is given. In general, a count of zero observed serious events does not establish that the underlying risk is zero; interpretation depends on the number monitored, duration and completeness of follow-up, and event ascertainment. Those details are not reported in the registry record. The listed counts alone do not establish a comprehensive safety profile.

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

The registry record establishes that a randomized, double-masked, vehicle-controlled study was conducted to evaluate AC-170 0.24% in the conjunctival allergen challenge model. It identifies ocular itching at duration of action as the primary outcome and describes how the symptom was scored and summarized. It also lists signs assessed at onset and duration time points. These details explain what the study was designed to measure.

They do not establish the comparative result. The registry record does not report the group-level primary endpoint scores, the estimated treatment contrast, a confidence interval, or a statistical test. As a result, the posted information cannot show whether the groups' itching scores differed, by how much, or with what precision. It also cannot support an interpretation of the secondary outcome comparisons.

The study's challenge model is a specific research setting. In general, a finding in a controlled allergen challenge model may not answer every question about symptoms or signs in other settings. The registry record does not provide results that could be considered for broader interpretation, nor does it report details needed to assess how the study population compares with other populations.

The safety counts describe recorded events among the listed risk sets, not a full benefit-risk assessment. The absence of reported serious adverse events in these groups does not demonstrate an absence of risk. The record does not provide event definitions, complete follow-up information, or a full narrative of safety findings.

The distinction is between a registered research question and an interpretable result. The design and endpoint definitions are recorded, but the numerical outcome estimates and statistical analyses needed to answer the primary comparison are not reported in the registry record. No claim about treatment efficacy or lack of efficacy can be based on the available outcome information.

13. Why This Trial Matters Statistically

This trial is statistically notable as a randomized, double-masked, vehicle-controlled evaluation using a challenge model and a symptom score measured on a bounded scale. The primary endpoint is described as a mean score, with a standard deviation, and the registry identifies the ITT population. These details make clear the intended outcome type and the general form of its summary.

At the same time, the record illustrates why endpoint definitions alone are not enough to interpret a trial. An estimate of the contrast between groups, together with a measure of uncertainty, is needed to describe the magnitude and precision of a primary finding. The registry record does not report these results. The study's stated aim and completed status cannot substitute for outcome data.

The record also lists 25 outcome measures and notes that the primary outcome has several categories or time points. This makes the missing analysis description especially relevant: readers cannot determine which comparisons were analyzed, how repeated or multiple assessments were treated, or whether a multiplicity strategy was used. These statistical details affect how evidence across outcomes should be read, but are not reported in the registry record.

Finally, safety counts need context beyond a simple event tally. Risk-set counts and affected-participant counts are useful descriptive information, but definitions, follow-up, and analysis methods shape their interpretation. This record gives some counts while leaving those details unreported. The statistical lesson is that transparent results require outcome estimates, uncertainty, analysis methods, and sufficient reporting of the population and data contributing to each 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 principal limitation for statistical interpretation is that the registry record does not report primary outcome values or a comparative analysis. It provides no arm-level means or standard deviations, treatment contrast, confidence interval, or p-value. Consequently, the primary endpoint cannot be quantitatively interpreted from this record, and the direction and precision of any observed difference are unknown.

The record lists 25 outcome measures and 0 analyses, and notes that the primary outcome includes several categories or time points. It does not report the analysis plan, the specific comparisons performed, or any multiplicity procedure. This leaves uncertainty about how the multiple measures and assessment occasions were handled. The protocol and statistical analysis plan are not reported in the registry record.

The primary population is identified as ITT, but participant flow, endpoint-specific denominators, missing-data counts, and missing-data methods are not reported in the registry record. The record also does not explain how the ITT population was defined in practice. Without this information, completeness and analysis-population details cannot be evaluated.

The design is described as randomized, double-masked, and parallel, but the randomization method, masking details, and group allocation at randomization are not reported. The sample-size assumptions for a planning illustration are described, but its numerical output and the trial's own sample-size justification are not reported in the registry record. The listed safety counts lack further details on event definitions and follow-up, and death counts are not reported in the registry record.

These are limitations of the information available in the registry record, not evidence that the study did not perform analyses or collect additional data. The record alone does not establish whether further analyses or documentation exist outside it.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Multi-Center, Evaluation of the Onset and Duration of Action of AC-170 0.24% Compared to Vehicle — NCT01881113.
• Registry record last updated 2017-11-09; status last verified 2017-10.
• Results first posted 2017-11-09.
• 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

NCT01881113 is recorded as a completed Phase 3, randomized, double-masked, vehicle-controlled, parallel study of AC-170 0.24% versus AC-170 0% in the conjunctival allergen challenge model of allergic conjunctivitis. Enrollment is listed as 101, with a recorded start of 2013-06 and primary completion in 2013-10.

The primary outcome is ocular itching at duration of action, identified as 8 hours + 30 minutes post-dose. It is a patient-assessed score on a 0-4 scale, averaged over both eyes, with mean and standard deviation specified and ITT identified as the population. The registry record does not report primary outcome estimates or a comparative analysis.

Safety counts list 0 serious adverse events among 51 at risk in the AC-170 0.24% group and among 50 at risk in the AC-170 0% group. Other adverse events are listed for 3 and 5 participants, respectively. Death figures, analysis details, and the trial's sample-size justification are not reported in the registry record.