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 Compare a New Eye Drop Formulation With Refresh Contacts® (NCT01844388), a randomized phase 3 study. The primary outcome is Percentage of Participants With Contact Lens Distance Visual Acuity Change From Baseline.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01844388 |
| Phase | Phase 3 |
| Condition | Contact Lens Lubrication |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 365 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Allergan |
| Results posted | Yes |
2. Clinical Question
Population
The primary endpoint population is described as the intent-to-treat population, including all randomized participants. The registry record concerns contact lens lubrication and reports distance visual acuity using the worse eye at baseline. Further eligibility details are not reported in the registry record.
Intervention
Participants assigned to the carboxymethylcellulose-based eye drop formula were instructed to place 1-2 drops in each eye a minimum of 4 times a day for 90 days. One of those daily uses could be to prepare the contact lens for insertion.
Comparator
The comparator was REFRESH CONTACTS®, described as a carboxymethylcellulose sodium-based eye drop solution. Its instructions were also 1-2 drops in each eye a minimum of 4 times a day for 90 days, with one daily use permitted to prepare the contact lens for insertion.
Primary question
The stated primary question concerns the percentage of participants whose contact lens distance visual acuity was categorized as better, unchanged, or worse from baseline to Day 90. The registry record gives category definitions, but numerical results for these categories are not reported in the registry record. It therefore does not establish how the groups compared on this endpoint.
3. Trial Design
The registry record describes a randomized, double-masked, parallel-group Phase 3 study. Its stated enrollment is 365. The listed condition is contact lens lubrication, and the brief summary describes a comparison of a new carboxymethylcellulose-based eye drop formula with REFRESH CONTACTS® for lubricating and rewetting contact lenses. The record gives a study start date of 2013-05-29 and primary completion date of 2013-12-02, with status marked completed.
Both treatment descriptions specify use in each eye at a minimum frequency of 4 times a day over 90 days. Each permits one of the daily applications to be used to prepare a contact lens for insertion. These descriptions establish the assigned regimens, but do not report adherence, actual exposure, use outside the instructions, or whether participants completed the regimen.
Randomization is intended to allocate participants to study groups by chance, while masking is intended to limit knowledge of treatment assignment during the study. The registry labels the study double-masked but does not specify which individuals were masked or how masking was maintained. The parallel model indicates that the listed groups were studied as separate arms rather than in a crossover sequence.
The record does not report the randomization method, allocation concealment procedures, eligibility criteria, study sites, or a detailed protocol. It also does not provide numerical primary-endpoint results. The enrollment figure is a design-record figure and should not be mistaken for the denominator used in each endpoint analysis; endpoint-specific analyzed counts are not reported 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.
Overall Study
| Stage | Carboxymethylcellulose Based Eye Drop Formula | REFRESH CONTACTS® |
|---|---|---|
| STARTED | 244 | 121 |
| COMPLETED | 236 | 114 |
| NOT COMPLETED | 8 | 7 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-treat Population included all randomized participants.
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 | Carboxymethylcellulose Based Eye Drop Formula | REFRESH CONTACTS® | Total |
|---|---|---|---|---|
| Participants analysed | 244 | 121 | 365 | |
| Age, Customized: <40 years | participants | 170 | 90 | 260 |
| Age, Customized: ≥40 years | participants | 74 | 31 | 105 |
| Sex: Female, Male: Female | Participants | 182 | 90 | 272 |
| Sex: Female, Male: Male | Participants | 62 | 31 | 93 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Contact Lens Distance Visual Acuity Change From Baseline, measured over Baseline, Day 90.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants with a change in contact lens distance visual acuity from baseline to Day 90. Visual acuity was measured for each eye using a LogMAR visual acuity eye chart, and the worse eye at baseline was selected for analysis. Using a prespecified eye can provide a consistent basis for classifying change rather than selecting the eye after observing the outcome.
The registry translates changes on the LogMAR scale into lines on the visual-acuity chart: a change of 0.1 is equivalent to a 1 line change. It reports three categories. “Better” means an increase in 2 or more lines; “No Change” means a change of +/- 1 line; and “Worse” means a decrease of 2 lines or more.
These categories describe direction and size of change in a way that can be read alongside the scale-based measurement. Categorizing the measure can make the result easier to interpret in terms of improvement, stability, or decline, but it also means that the reported endpoint is a distribution across categories rather than a single continuous change value. The registry record does not report category counts or percentages, uncertainty intervals, or a numerical between-group comparison. The endpoint’s definition is available, but its observed results are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary visual-acuity endpoint and describes how change was classified, but it does not report the numerical outcome for either group. In particular, the percentage categorized as better, no change, or worse at Day 90 is not reported in the registry record. Without those results, the relative pattern between the assigned eye drop regimens cannot be assessed from this record.
The endpoint is categorical. That matters because the distribution across all three categories may carry information that a single contrast would not capture. A comparison based only on one category, or a collapse of categories, would require a specified analysis and a clear rationale. The registry notes that the primary outcome has several categories or time points and is not reduced to one comparison. As a result, there is no single primary contrast available in the record to interpret as an estimated difference between groups.
No confidence interval, p-value, or other inferential statistic for the primary endpoint is reported in the registry record. A confidence interval, in general, conveys the range of values compatible with the data under the analysis assumptions; its width reflects precision. Without an estimate and interval, readers cannot judge the magnitude or precision of a group difference. Nor can they distinguish a small, uncertain difference from a larger, more precisely estimated one.
The trial is marked completed, but completion status does not itself provide evidence about the outcome. The stated enrollment of 365 also does not reveal how many participants contributed data to the primary endpoint, whether data were missing, or how any missing measurements were handled. Those details are not reported in the registry record.
The safety information is separate from the primary efficacy endpoint. The record lists serious adverse events for both groups, as well as a serious-event term, but these figures do not fill the gap in the visual-acuity results. Safety counts and a visual-acuity comparison answer different questions and should not be substituted for each other.
Accordingly, the posted record supports a description of the design, assigned regimens, endpoint definition, and reported safety counts. It does not support a numerical conclusion about the primary endpoint or about the comparative effect on visual acuity. Such conclusions would require outcome results and analysis details not reported in the registry record.
9. Statistical Methods Explained
The study design is described as randomized, double-masked, and parallel-group. In general, random allocation is used to reduce systematic differences between treatment groups at assignment. Masking can limit the influence of treatment knowledge on care, outcome assessment, or reporting. These are general methodological purposes; the registry record does not detail the procedures used to achieve them or identify which study personnel were masked.
What does the primary endpoint measure?
The primary measure is the percentage of participants in each visual-acuity change category between baseline and Day 90. The worse eye at baseline was selected from measurements made for each eye. The scale is LogMAR, with a change of 0.1 corresponding to a 1 line change. The categories distinguish better, no change, and worse according to the line-change definitions in the record. Because these categories are mutually descriptive outcome states, a complete interpretation would consider their distribution by group rather than assume that any single category represents the whole endpoint.
Why does the category structure matter?
General statistical interpretation depends on how an outcome is encoded and compared. A continuous score preserves the measured scale, while categories summarize observations into groups. Categorization can make changes easier to communicate, but it may discard distinctions among values within a category. A comparison might analyze category proportions, use a model for categorical outcomes, or prespecify a particular category contrast. The registry record does not report which approach was used. It explicitly indicates that the primary outcome has several categories or time points and is not reduced to one comparison.
The outcome is expressed as a percentage of participants with an event, but the underlying category-specific counts and denominators are absent. Percentages require an analyzed denominator, and differences between percentages require a defined contrast. Neither should be inferred from the overall enrollment figure. The record does not state how many participants had an evaluable baseline and Day 90 measure, how incomplete observations were treated, or whether the analysis used all randomized participants as planned in the population description.
What can a confidence interval tell a reader?
In general, a confidence interval accompanies an estimated effect and expresses statistical uncertainty under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, while the location of the interval indicates which effect values remain compatible with the data. It does not indicate the probability that a particular treatment effect is true. Here, no primary-endpoint estimate or interval is reported in the registry record, so precision cannot be evaluated.
A p-value, in general, measures how unusual the observed data or more extreme data would be under a specified null hypothesis and model. It is not a measure of the size or clinical importance of an effect. The registry record reports no primary-endpoint p-value, and the multiple endpoint categories make it especially important not to invent a single comparison or its significance result.
How should planning assumptions be read?
The record describes a planning illustration framework using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It defines the effect to detect as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the study detected an effect. The record does not report the trial's own sample-size justification. Since the primary outcome is not reduced to one comparison and its numerical effect is not reported, these assumptions do not supply an interpretable primary-endpoint estimate.
General planning calculations depend on the endpoint, the target effect, variability or event frequency, allocation, and the analysis method. For binary or categorical outcomes, the assumed group proportions and the exact contrast matter. If assumptions do not reflect the eventual analysis or observed data, the resulting planning figure may not describe the precision achieved. No additional planning inputs or trial-specific justification are reported in the registry record.
Why can over-dispersion matter?
In general, over-dispersion means that observed variability is greater than a statistical model expects. If a model assumes less variability than the data contain, standard errors can be too small and uncertainty can be understated. Appropriate methods can account for extra variation. The registry endpoint is categorical and no over-dispersion model or variance adjustment is described; there is no basis to say that over-dispersion was present or that a particular adjustment was used.
The registry also lists no analyses in its analysis count. That does not establish that no analysis was conducted outside the record; it means analysis details and numerical inferential results are not reported in the registry record. The reported endpoint definition, design labels, and safety counts should therefore be distinguished from a complete statistical analysis report.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome includes three categories and is described over baseline and Day 90. The registry record notes that it is not reduced to one comparison. When an outcome has multiple categories or when several comparisons are considered, general statistical practice requires clarity about which contrast is primary and how multiplicity is handled. Testing multiple hypotheses without an appropriate plan can increase the chance of a misleading positive finding. The registry record does not report a multiplicity strategy, a hierarchy of comparisons, or whether any adjustment was made.
Missing outcome data can affect both the estimated category percentages and the comparison between groups. The primary population is described as intent-to-treat and includes all randomized participants, but that population definition does not specify how participants without an observed Day 90 measure were handled. The record does not report missingness by group, reasons for missing measurements, imputation, sensitivity analyses, or the endpoint-specific analysis denominators.
The record reports an enrollment of 365, but the primary endpoint result and analyzed counts are not reported. Enrollment cannot be substituted for the number contributing endpoint data. It is therefore not possible to assess attrition, the impact of missing data, or whether the analysis followed a particular missing-data strategy. These omissions limit interpretation of both the estimated outcome and its uncertainty.
Analysis populations beyond the stated intent-to-treat description are not reported in the registry record. The record also does not provide a statistical analysis plan or details about interim analyses. No conclusions about those procedures should be inferred from the completed status or the listed design.
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 |
|---|---|---|---|
| Carboxymethylcellulose Based Eye Drop Formula | 1 | 244 | 0.4% |
| REFRESH CONTACTS® | 0 | 121 | 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 |
|---|---|
| Carboxymethylcellulose Based Eye Drop Formula | 0 of 244 |
| REFRESH CONTACTS® | 0 of 121 |
Most frequent serious adverse event terms
| Event term | Organ system | Carboxymethylcellulose Based Eye Drop Formula | REFRESH CONTACTS® |
|---|---|---|---|
| Abortion spontaneous | Pregnancy, puerperium and perinatal conditions | 1 of 182 | 0 of 90 |
Serious events with the highest arm-level rate: abortion spontaneous (0.5%).
The safety record lists serious adverse events among participants at risk in each group. For the carboxymethylcellulose-based eye drop formula, the listed serious-event count is 1 among 244 at risk. For REFRESH CONTACTS®, it is 0 among 121 at risk. Other adverse events are listed as 0 among 244 at risk in the formula group and 0 among 121 at risk in the comparator group. These figures are descriptive counts as recorded, not a complete safety analysis.
The registry lists “Abortion spontaneous” at 0.5% among the top serious terms. It does not provide enough detail in the record to establish the term's arm-specific context or its relationship to the listed serious-event counts. Deaths are not reported in the registry record.
These counts should be interpreted with attention to the recorded at-risk denominators and the limited information about event definitions, follow-up, and ascertainment. A count of zero in a group does not establish that an event is impossible, and a small count cannot by itself characterize comparative risk. The record does not report a formal between-group safety comparison, uncertainty intervals, or a detailed account of adverse-event monitoring. Safety findings do not answer the primary visual-acuity question.
12. What the Result Does, and Does Not, Mean
The registry record establishes that the study was designed to compare a carboxymethylcellulose-based eye drop formula with REFRESH CONTACTS® and that its primary endpoint concerned categorized change in contact lens distance visual acuity from baseline to Day 90. It also defines how the three categories were assigned and identifies the worse eye at baseline for analysis. These details make the intended question understandable.
The record does not report the numerical results for the primary endpoint. It therefore cannot show how many participants in either group were classified as better, unchanged, or worse, nor can it quantify a between-group difference. No confidence interval or primary-endpoint p-value is reported. The result's magnitude and precision are consequently unknown from this record.
The study's completed status and stated enrollment do not resolve that uncertainty. They describe the record's status and planned or recorded enrollment, not the observed visual-acuity outcome or the number of participants included in its analysis. Without endpoint denominators and missing-data details, the completeness of the primary outcome data cannot be assessed.
The reported serious adverse-event counts are limited safety information and should be read separately from efficacy. They do not establish a comparative visual-acuity result or provide a comprehensive account of safety. The registry's serious-event term listing also lacks detail needed for an arm-specific interpretation.
In general, statistical evidence is best interpreted through an estimated effect, its uncertainty, the analysis population, and a clear description of how outcomes and missing data were handled. Those elements are not available for the primary endpoint in the registry record. No conclusion about the direction, size, precision, or statistical significance of the visual-acuity comparison is justified from the posted results alone.
13. Why This Trial Matters Statistically
This trial illustrates an important distinction between a well-described endpoint and a reported result. The record specifies the visual-acuity scale, the eye selected for analysis, the assessment time points, and the categories used to classify change. That supports understanding what the endpoint was intended to capture, but it does not provide the data needed to judge the comparison between groups.
The category structure is statistically consequential. Better, unchanged, and worse are not interchangeable summaries: their proportions describe different patterns of outcome. A single contrast would need to be defined and justified, particularly when an endpoint is reported across several categories. The record explicitly does not reduce the outcome to one comparison, so a reader should not treat it as though a single effect estimate had been reported.
The record also makes clear why enrollment alone cannot answer questions about precision. Precision depends on the analyzed data and the variation in outcomes, as well as the statistical method. Without category counts, analysis denominators, an effect estimate, or an uncertainty interval, the stated enrollment cannot show how accurately the primary comparison was estimated.
Finally, the record separates descriptive safety counts from the primary visual-acuity outcome. Each has a different interpretation and information need. This is a useful reminder that completing a trial and recording selected safety figures do not substitute for reporting the primary endpoint and its analysis. Transparent reporting of estimates, uncertainty, analysis populations, and missing-data handling is necessary for readers to assess what the study's results mean.
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 primary limitation for interpretation is that numerical results for the primary visual-acuity endpoint are not reported in the registry record. The category-specific percentages and counts, group comparison, and uncertainty measures are unavailable. The record therefore allows assessment of the endpoint definition but not the observed efficacy result.
Additional analysis details are not reported: the exact statistical method for the categorical outcome, the contrast selected, the handling of multiple categories, the endpoint-specific denominators, and how missing measurements were addressed. Although the intent-to-treat population is defined as including all randomized participants, the record does not explain how that population description was implemented for participants without endpoint data.
The record does not report a trial-specific sample-size justification, a statistical analysis plan, interim analyses, or detailed procedures for randomization and masking. It also does not describe eligibility criteria or provide sufficient safety-analysis detail to interpret the serious-event term by group. These omissions should not be filled by assumptions about usual trial practice.
The listed serious-event counts are limited descriptive information and do not include a formal comparative analysis or uncertainty estimates. The registry's completed status does not remove these reporting limitations. Consequently, conclusions about the primary endpoint's direction, magnitude, precision, or significance cannot be drawn from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Compare a New Eye Drop Formulation With Refresh Contacts® — NCT01844388.
- Registry record last updated 2019-04-16; status last verified 2019-04.
- Results first posted 2014-09-29.
- 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
NCT01844388 is a completed Phase 3 randomized, double-masked, parallel-group study comparing a carboxymethylcellulose-based eye drop formula with REFRESH CONTACTS®. The record lists enrollment of 365, with a start date of 2013-05-29 and primary completion date of 2013-12-02. Both regimens specify 1-2 drops in each eye a minimum of 4 times a day for 90 days.
The primary endpoint is the percentage of participants in visual-acuity change categories from baseline to Day 90, assessed using the worse eye at baseline. Category definitions are reported, but numerical primary-endpoint results, analysis details, and endpoint denominators are not reported in the registry record. Serious adverse-event counts are listed as 1 among 244 at risk for the formula group and 0 among 121 at risk for REFRESH CONTACTS®; other adverse events are listed as 0 in both groups. The record does not report deaths.