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 A Study to Evaluate the Duration of LASTACAFT® in Acute Allergic Conjunctivitis (NCT01470118), a randomized phase 4 study. The primary outcome is Ocular Itching Evaluated by the Subject at 3, 5, and 7 Minutes Post Challenge on Day 0 at Hour 16.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01470118 |
| Phase | Phase 4 |
| Condition | Conjunctivitis, Allergic |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 127 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Allergan |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerned people with allergic conjunctivitis. The primary outcome population is described as the Intent-to-Treat population, defined in the registry record as all randomized subjects. The record lists an enrollment of 127, but it does not report participant characteristics or outcome data by randomized group.
Intervention
The intervention was LASTACAFT® (alcaftadine 0.25% ophthalmic solution). The arm description specifies one drop in each eye at Day 0 and Day 14. The study was designed to evaluate the duration of action of this treatment in relation to ocular itching associated with allergic conjunctivitis.
Comparator
There were two comparator arms: Pataday™ (olopatadine 0.2% ophthalmic solution) and placebo, described as dextran 70 0.1%/hydroxypropyl methylcellulose 0.3%. Each description specifies one drop in each eye at Day 0 and Day 14. The registry record does not report results comparing these arms.
Primary question
The primary outcome was subject-evaluated ocular itching after challenge at 3, 5, and 7 minutes, on Day 0 at hour 16. Scores ranged from 0=None to 4=Incapacitating Itch with an Irresistible Urge to Rub, with 0.5 increments allowed; lower scores indicated less itching. The record does not report the group scores or statistical comparisons needed to establish how the groups differed.
3. Trial Design
This was a randomized, double-masked, parallel Phase 4 study sponsored by Allergan. Its registry title identifies the study as an evaluation of the duration of LASTACAFT® in acute allergic conjunctivitis. The brief summary describes a comparison of LASTACAFT® and Pataday™ with artificial tears, called placebo in the arm description, for prevention of ocular itching associated with allergic conjunctivitis.
The record lists an enrollment of 127 and the condition as allergic conjunctivitis. The study began in 2011-10, had primary completion in 2011-12, and is marked completed. These administrative details describe the registered trial; they do not establish how many participants contributed data to any particular outcome.
The three arms were LASTACAFT® (alcaftadine 0.25%), Pataday™ (olopatadine 0.2%), and placebo (dextran 70 0.1%/hydroxypropyl methylcellulose 0.3%). Each arm description specifies a drop in each eye at Day 0 and Day 14. The record does not report further details about allocation procedures, how masking was maintained, or whether participants completed both administrations.
The primary outcome is described at Day 0, hour 16, with itching assessed at 3, 5, and 7 minutes after challenge. Secondary outcomes cover redness, chemosis, eyelid swelling, and tearing at specified post-challenge times on Day 14 at hour 24. The registry record does not report a statistical analysis plan, a sample-size justification, or results for these outcomes.
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
| Stage | LASTACAFT® (Alcaftadine 0.25%) | Pataday™ (Olopatadine 0.2%) | Placebo (Dextran 70 0.1%/Hydroxypropyl Methylcellulose 0.3%) |
|---|---|---|---|
| STARTED | 43 | 43 | 41 |
| COMPLETED | 38 | 38 | 39 |
| NOT COMPLETED | 5 | 5 | 2 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-Treat: All randomized subjects
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 | LASTACAFT® (Alcaftadine 0.25%) | Pataday™ (Olopatadine 0.2%) | Placebo (Dextran 70 0.1%/Hydroxypropyl Methylcellulose 0.3%) | Total |
|---|---|---|---|---|---|
| Participants analysed | 43 | 43 | 41 | 127 | |
| Age Continuous | Years | 39.3 (SD 12.44) | 37.0 (SD 14.84) | 39.3 (SD 12.31) | 38.5 (SD 13.21) |
| Sex: Female, Male: Female | Participants | 31 | 33 | 28 | 92 |
| Sex: Female, Male: Male | Participants | 12 | 10 | 13 | 35 |
6. Primary Endpoint
The registry lists the primary outcome as Ocular Itching Evaluated by the Subject at 3, 5, and 7 Minutes Post Challenge on Day 0 at Hour 16, measured over Day 0 Hour 16.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Scores on a Scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint measures subject-reported ocular itching after challenge. Subjects rated itching on a numeric analog scale from 0=None to 4=Incapacitating Itch with an Irresistible Urge to Rub, allowing 0.5 increments. The description says that each subject’s scores for both eyes were averaged to make one score per subject. A lower score was defined as indicating less itching.
Assessment was scheduled at 3, 5, and 7 minutes post challenge on Day 0 at hour 16. These are multiple observations within the endpoint description, not a single reported value. The registry record does not specify how those observations were combined for an overall comparison, and no group means, standard deviations, or treatment comparisons are reported.
As a general statistical matter, a continuous score can describe the degree of a symptom rather than only whether it occurred. A mean summarizes the average score, while a standard deviation describes how spread out individual scores are around that mean. The endpoint is relevant to the stated question because it records the symptom the study sought to evaluate. However, without posted results, it is not possible to assess the observed itching scores, their variability, or the precision of any between-group difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies ocular itching as the primary outcome and specifies that it was assessed at several post-challenge times. It also identifies the intended primary population as all randomized subjects. However, the record reports no analysis results for this outcome. There are no posted group means, standard deviations, estimated differences, confidence intervals, or p-values from which to describe the direction, size, or precision of a treatment comparison.
This absence matters for interpretation. A study objective and an outcome definition establish what investigators intended to measure, but they do not show what the measurements were. The record’s description of the scale says that lower scores indicate less itching; it does not provide evidence that any arm had lower scores. It is therefore not possible to conclude from the registry record whether the groups differed, whether any difference was small or large, or how compatible the data were with different possible effects.
The primary outcome includes ratings at 3, 5, and 7 minutes after challenge. The registry record does not report a single comparison that combines these times, nor does it provide separate results by time. It also does not report the outcome’s observed sample sizes or explain how missing ratings, if any, were handled. Those omissions prevent an assessment of whether the planned population and measurement schedule were reflected in the analyzed data.
The trial is marked completed, but completion status is not a substitute for results. Similarly, its randomized, double-masked, parallel design describes important features of how the study was organized, not the magnitude or reliability of an outcome effect. Randomization can support fair comparisons when analyzed appropriately, and masking can reduce some forms of bias, but neither feature reveals results that are not reported.
The registry does report safety counts separately. Those counts are not evidence about the primary itching endpoint and cannot fill the gap in efficacy-related outcome reporting. The appropriate reading is therefore limited: the record documents a trial designed to compare three eye-drop regimens and defines how itching was to be scored, but it does not permit a statistical interpretation of the primary outcome.
9. Statistical Methods Explained
What does the primary measure represent?
The primary measure is a continuous symptom score. The registry record states that subjects rated ocular itching from 0=None to 4=Incapacitating Itch with an Irresistible Urge to Rub, permitting 0.5 increments. It also states that the two-eye scores were averaged for each subject, yielding one score per subject at an assessment. This produces a numerical summary of symptom intensity rather than a simple yes-or-no outcome.
The registry lists the mean as the outcome parameter and standard deviation as the dispersion measure. In general, a mean describes the average score in a group. A standard deviation describes how much individual scores tend to vary around that average. Neither is available as an observed result in the registry record, so the group averages and variability cannot be compared.
How should a treatment comparison be understood?
In general, a treatment comparison for a continuous outcome can be expressed as a difference between group means. The estimate describes the observed contrast, while a confidence interval describes the range of values reasonably compatible with the data under the method’s assumptions. A narrow interval indicates more precision than a wide interval, but an interval’s width depends on factors including the amount of information and variability in the outcome. No estimate or confidence interval for ocular itching is reported in the registry record.
A p-value, when reported, assesses how compatible the observed data are with a specified null hypothesis under a statistical model. It is not a measure of clinical importance, nor does it establish that an effect is absent when it is not small. No p-value or test result for the primary outcome is reported. Without the numerical results, neither statistical significance nor the practical size of a difference can be assessed.
Why do the assessment times matter?
The primary outcome description specifies ratings at 3, 5, and 7 minutes post challenge. Repeated measurements can be analyzed in different ways. Investigators might report each time separately or use a model that accounts for the relationship among measurements from the same subject. These approaches answer different questions and can require different assumptions. The record does not state which approach was used, whether a single time was designated for the main comparison, or how the multiple primary assessment times were handled.
As a general matter, measurements from the same person are not independent observations. A method that treats correlated observations as independent can give misleading estimates of uncertainty. A repeated-measures method can account for within-person correlation, but the choice of model and its assumptions should be specified. The analysis method is not reported in the registry record, so it cannot be evaluated for this endpoint.
What do randomization and masking contribute?
Randomization is intended to make treatment assignment independent of participant characteristics, on average, and thereby support comparisons between arms. It does not guarantee that groups will be identical, nor does it correct problems arising after assignment, such as missing outcome data or departures from the analysis plan. The record identifies the trial as randomized but does not report details of the randomization procedure or the number analyzed for the primary outcome.
Double masking is intended to limit the influence of treatment knowledge on participant reports, investigator assessments, or trial conduct. That can be especially relevant when an outcome is reported by participants. The record states that masking was double but does not describe who was masked or how masking was maintained. These details are not reported in the registry record.
What can be inferred from the posted statistical information?
The registry record identifies the planned outcome type and its mean and standard deviation summaries, but it contains no reported analyses for the trial. The primary endpoint is not reduced to one comparison because it has several categories or time points, according to the record’s outcome note. There is consequently no reported treatment-effect estimate to interpret or recalculate. Any general discussion of means, variability, confidence intervals, or repeated-measures analysis explains statistical concepts only; it does not describe an analysis performed in this trial.
Sample-size planning is also distinct from an observed result. A planning illustration estimates the number of participants that might be needed under stated assumptions, whereas observed power is not a measure that can be recovered from a result after the fact. The registry describes general planning assumptions, but does not report a trial-specific sample-size justification or analysis results that would support a planning illustration for a single primary comparison. Such planning information cannot replace the missing endpoint results.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when several outcomes, assessment times, or treatment comparisons are examined. In general, testing many hypotheses can increase the chance that at least one result appears statistically notable by chance. Common approaches include specifying a hierarchy, adjusting significance thresholds, or treating analyses as exploratory. The registry record does not report a multiplicity strategy or analysis plan.
The primary endpoint includes itching scores at 3, 5, and 7 minutes post challenge. The record also lists secondary outcomes for conjunctival, ciliary, and episcleral redness; chemosis; eyelid swelling; and tearing. These outcomes are assessed at 7, 15, and 20 minutes post challenge on Day 14 at hour 24. The record does not report which comparisons were prioritized, how repeated time points were handled, or whether any adjustment was made for multiple testing. No outcome analyses are reported, so the impact of multiplicity on results cannot be assessed.
The primary population is described as Intent-to-Treat: all randomized subjects. That definition indicates an intended analysis population, but the record does not report the number of subjects contributing primary outcome data or whether all randomized subjects were included in an analysis. The approach to missing scores, incomplete follow-up, or other exclusions is not reported in the registry record. These details matter because missingness can affect both the representativeness of the analyzed participants and the validity of statistical uncertainty estimates.
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 |
|---|---|---|---|
| LASTACAFT® (Alcaftadine 0.25%) | 0 | 43 | 0.0% |
| Pataday™ (Olopatadine 0.2%) | 0 | 42 | 0.0% |
| Placebo (Dextran 70 0.1%/Hydroxypropyl Methylcellulose 0.3%) | 0 | 41 | 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 |
|---|---|
| LASTACAFT® (Alcaftadine 0.25%) | 0 of 43 |
| Pataday™ (Olopatadine 0.2%) | 0 of 42 |
| Placebo (Dextran 70 0.1%/Hydroxypropyl Methylcellulose 0.3%) | 0 of 41 |
The registry record lists serious adverse events as affecting 0 participants in the LASTACAFT® group, 0 in the Pataday™ group, and 0 in the placebo group. The corresponding numbers listed at risk are 43, 42, and 41. It also lists other adverse events as affecting 0 participants in each group, with the same group-specific numbers at risk.
These entries are counts in the registry safety record. They should be read as reported event counts for the listed groups, not as a statistical comparison or as proof that no adverse events occurred outside the categories or reporting captured in the record. The list of top serious adverse event terms is empty. Death counts are not reported in the registry record.
Safety counts do not describe the primary itching outcome, and the registry record does not provide statistical comparisons for the adverse-event counts. The listed numbers at risk should not be treated as the number analyzed for the primary endpoint unless that is reported separately; it is not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, double-masked, parallel study was designed to compare LASTACAFT®, Pataday™, and placebo in people with allergic conjunctivitis. It identifies the primary symptom, the scale used to rate it, and the times at which ratings were scheduled. It also identifies secondary symptom and sign assessments and provides group-specific adverse-event counts.
Those design details do not establish the results of the trial. The registry record does not report the primary outcome scores or analyses, so it cannot support a conclusion about the direction or magnitude of differences among the groups. It also does not provide confidence intervals or other measures of precision. A description of a lower score as indicating less itching defines how the scale should be read; it is not evidence that a group achieved a lower score.
The absence of reported primary outcome results should not be interpreted as evidence of no difference. Without estimates and their uncertainty, the record cannot distinguish a small effect from a larger one, or a precise estimate from an imprecise one. Nor can it establish whether the secondary outcomes support or contradict the stated study objective, because their results are not reported.
The trial’s completed status and its enrollment figure are administrative and design details, not evidence of treatment effect. Likewise, the zero adverse-event counts in the registry record are limited to the reported categories and groups. They do not answer the primary symptom question and should not be generalized beyond the recorded safety information.
Accordingly, the record is informative about what the trial set out to measure and how the arms were described, but it is insufficient for judging comparative outcome effects or their precision. Any broader interpretation would require results and analysis details that are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between a registered design and a reported analysis. The record specifies a randomized, double-masked, parallel comparison and defines a participant-reported continuous outcome. These details clarify the intended question and measurement, but they are not substitutes for observed group results.
The endpoint has multiple post-challenge assessment times. That structure raises an important general design and analysis issue: conclusions can depend on whether investigators focus on a particular time, report each time separately, or analyze the measurements jointly. The registry record does not report the method used to address those observations. Without that information and the resulting estimates, readers cannot judge how the outcome was summarized or how uncertainty was calculated.
The trial also lists several secondary outcomes with multiple assessment times. In general, a set of outcomes can create multiplicity concerns if many comparisons are tested. A prespecified statistical strategy helps readers distinguish primary evidence from secondary or exploratory findings. The registry record does not report such a strategy, and it contains no outcome analyses to assess.
These limitations do not negate the value of defining an outcome clearly. The scale, scoring direction, averaging of both eyes, and assessment schedule give readers a basis for understanding what the planned measure represents. They also make clear what information would be necessary for a full statistical interpretation: group summaries, treatment contrasts, uncertainty estimates, analysis populations, and methods for repeated measurements and missing data.
The central statistical lesson is that design features can support trustworthy inference only when results and analysis methods are available for scrutiny. Here, the registry record documents the comparison and its measurements, but not the evidence needed to estimate comparative effects.
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.
A central limitation for interpretation is that the registry record reports no primary outcome analysis. It does not include group means, standard deviations, treatment-effect estimates, confidence intervals, or p-values. Consequently, the direction, size, and precision of any differences in ocular itching cannot be assessed.
The primary outcome is described at 3, 5, and 7 minutes post challenge, but the record does not state how these observations were combined or whether a particular time was the principal comparison. It also does not report the analysis method for repeated observations, or how multiplicity was addressed across primary and secondary assessments.
Although the primary population is identified as all randomized subjects, the record does not provide the number contributing primary outcome data or the handling of missing observations. Details of participant characteristics, allocation procedures, masking implementation, adherence, and departures from the planned regimen are not reported in the registry record. These omissions limit assessment of the trial’s conduct and of how representative the analyzed population would be, if an analysis were available.
The registry describes the study as completed and lists an enrollment of 127, but those details do not establish the number included in each outcome analysis. The safety counts are reported separately and cannot be assumed to describe the primary outcome analysis population. The registry record also does not report a trial-specific sample-size justification or statistical plan.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Evaluate the Duration of LASTACAFT® in Acute Allergic Conjunctivitis — NCT01470118.
- Registry record last updated 2013-02-21; status last verified 2013-01.
- Results first posted 2013-02-21.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes a completed, randomized, double-masked, parallel Phase 4 study sponsored by Allergan. It lists allergic conjunctivitis as the condition, an enrollment of 127, a start in 2011-10, and primary completion in 2011-12. The three arms were LASTACAFT® (alcaftadine 0.25%), Pataday™ (olopatadine 0.2%), and placebo.
The primary outcome was subject-evaluated ocular itching at 3, 5, and 7 minutes post challenge on Day 0 at hour 16. The scale ranged from 0=None to 4=Incapacitating Itch with an Irresistible Urge to Rub, allowing 0.5 increments; lower scores indicated less itching. Secondary outcomes covered redness, chemosis, eyelid swelling, and tearing.
The registry record reports zero serious and other adverse events in each listed group, but it does not report primary outcome analyses, estimates, or uncertainty intervals. Statistical conclusions about comparative itching outcomes therefore cannot be drawn from the record.