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 Non-dispensing Study to Check Prescription Equivalence of Two Daily Disposable Toric Contact Lens Types (NCT01120782), a randomized na study. The primary outcome is Prescription Equivalence.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01120782 |
| Phase | NA |
| Condition | Astigmatism |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Single |
| Enrollment | 45 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johnson & Johnson Vision Care, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
People with astigmatism were enrolled. The primary endpoint population is described as all completed subjects, but the number who completed the study is not reported in the registry record. Enrollment was 45; that figure should not be assumed to equal the completed-subject count.
Intervention
A daily disposable etafilcon A toric contact lens with a new wetting agent was one of the two lenses tested. Each lens was worn bilaterally for a maximum of 15 minutes.
Comparator
The comparator was a marketed etafilcon A toric contact lens. The study used a crossover arrangement: participants wore both lens types, with the order randomized.
Primary question
After 15 minutes of lens wear, for how many completed subjects was the prescription the same for the two lenses? The registry record defines this count but does not report the count, its denominator, or a statistical comparison. It also does not report a prespecified acceptable difference or an equivalence margin. Therefore, the record does not establish whether the prescriptions were judged equivalent under a formal statistical criterion.
The stated purpose was to determine whether the prescription found for the new lens would be a good match to the prescription found for the existing brand. That is a question about agreement between prescription determinations, rather than a reported comparison of long-term outcomes. The available record describes the procedures and endpoint, but not the endpoint result or the method used to analyze it. The interpretation must therefore remain limited to the question the study set out to address and the information the registry record actually contains.
3. Trial Design
The study was randomized, single-masked, and used a crossover model. In a crossover study, participants receive or experience each intervention in a planned sequence, so comparisons can be made within participants. Here, the two sequences were new lens followed by marketed lens, or marketed lens followed by new lens. The order was randomized. The registry record does not say who was masked, how masking was maintained, or how the random sequence was generated or concealed.
Each lens was worn bilaterally for a maximum of 15 minutes. The primary endpoint was assessed after 15 minutes of lens wear and counted subjects whose prescription was the same for both lenses. The endpoint population is stated as all completed subjects. The record does not report the number who completed the study, whether anyone discontinued, or how incomplete observations were handled.
Enrollment was 45, and the study status is completed. The start and primary completion dates are both recorded as 2010-02-01. These registry dates do not provide further detail about the order or timing of each participant’s visits. Washout procedures, the interval between lens wear, and other sequence-related procedures are not reported in the registry record.
The trial is listed as phase NA, which is consistent with the record describing device interventions rather than a drug phase. The sponsor was Johnson & Johnson Vision Care, Inc. The registry record identifies the study as non-dispensing and describes a brief wear period; it does not report additional protocol details, such as eligibility criteria beyond the condition listed, the setting, or how prescriptions were assessed.
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: Due to test article shipment error, one clinical site did not receive control test article in a required cylinder and all screened/enrolled subject were unable to be fitted according to the protocol and were discontinued.
Overall Study
| Stage | All Subjects |
|---|---|
| STARTED | 45 |
| COMPLETED | 34 |
| NOT COMPLETED | 11 |
Reasons for not completing this period:
| Reason | All Subjects |
|---|---|
| Test article shipping error | 11 |
Analysis population for the primary outcome, as defined in the registry: All completed 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 | All Subjects |
|---|---|---|
| Participants analysed | 45 | |
| Age, Continuous | years | 29.2 (SD 5.10) |
| Sex: Female, Male: Female | Participants | 13 |
| Sex: Female, Male: Male | Participants | 32 |
| Region of Enrollment: United States | participants | 45 |
6. Primary Endpoint
The registry lists the primary outcome as Prescription Equivalence, measured over after 15 minutes of lens wear.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of subjects whose prescription was the same for the two tested lenses, assessed after 15 minutes of lens wear. Its unit is participants, and the stated endpoint population is all completed subjects. The registry record does not give the observed count or the number of completed subjects contributing to that count.
This endpoint was selected to address whether prescription determinations for the new lens matched those for the marketed lens. Counting participants with the same prescription gives a direct description of exact agreement as defined by the registry. It can be easy to interpret, but it does not describe how far apart prescriptions were when they did not match, nor does it show the pattern of any differences. Those details are not reported in the registry record.
As a general statistical point, an endpoint that counts exact matches answers a different question from a continuous measure of average difference or a formal equivalence analysis. A formal equivalence conclusion ordinarily depends on a prespecified margin defining what differences are acceptable and an analysis that evaluates uncertainty against that margin. The registry record does not report such a margin or the analysis. The endpoint definition alone therefore identifies what was to be counted, but cannot establish a formal equivalence result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record states a clear primary outcome concept: count the completed subjects whose prescriptions were the same for the two lenses after 15 minutes of wear. It does not include the observed count, the completed-subject denominator, an effect estimate, a confidence interval, or a p-value. It also lists no primary statistical analyses. Consequently, the posted record does not permit readers to quantify the observed degree of prescription agreement or its precision.
The study’s crossover structure means that the intended comparison was within participants, because participants wore both lens types. Randomization determined which lens was worn first. This design can account for stable participant characteristics in a within-person comparison, but its interpretation may also depend on period, sequence, and carryover effects. Whether these issues were assessed, and how, is not reported in the registry record. The brief maximum wear period is described, but procedural details beyond that are not included.
The word “equivalence” in the outcome title should not be read by itself as a statistical finding. The recorded endpoint is an exact-match count. A count can describe how many prescriptions matched, but an equivalence claim requires an analysis against a defined criterion and attention to uncertainty. Neither an equivalence margin nor a result from such an analysis is reported. No conclusion about equivalence can be drawn from the endpoint title or study objective alone.
The adverse-event entry records zero serious adverse events among 45 subjects at risk and zero other adverse events among 45 subjects at risk. These safety counts describe the registry entry; they do not fill the gap in the primary efficacy result. The death count is not reported in the registry record. The study’s completed status and enrollment figure likewise do not supply the missing endpoint result.
In short, the record describes the comparison and the planned endpoint but offers no reported primary outcome estimate or analysis. Any interpretation of the magnitude, statistical uncertainty, or formal equivalence of the prescription comparison would require information not reported in the registry record.
9. Statistical Methods Explained
Design and comparison. The study is described as randomized, single-masked, and crossover. As a general statistical explanation, randomization of treatment order is intended to reduce systematic differences in which intervention is experienced first. A crossover design allows each participant to contribute observations under both interventions, which can make within-person comparisons informative when measurements from the same person are related. The registry record does not describe the randomization method, the identity of the masked party, or procedures for maintaining masking.
For a crossover comparison, sequence and period can matter. Sequence describes the order in which the lenses are worn; period refers to the position of a measurement in that order. Carryover is a possible influence of an earlier intervention on a later measurement. These are general design concepts, not claims that such effects occurred in this study. The record does not say whether the analysis accounted for sequence, period, or carryover, or whether a washout was used.
Endpoint scale. The primary outcome is a count of participants with the same prescription for both lenses, and the registry classifies it as binary. As a general explanation, an individual participant’s result can be represented as a match or no match, while the reported endpoint count aggregates the number of matches in the analysis population. A proportion would require both that count and its denominator. Neither is reported as an outcome result in the registry record, so no proportion or uncertainty estimate can be stated.
Agreement and equivalence. Exact agreement is one way to summarize whether two assessments coincide. It does not express the size or direction of disagreements, and it may not distinguish small from large differences when both are classified as non-matches. As a general statistical point, formal equivalence testing asks whether the data are sufficiently compatible with differences lying within a prespecified acceptable range. It requires a defined margin and a suitable analysis. The registry record does not report a margin, an equivalence test, or the result of any such analysis. The term in the endpoint title should therefore be understood as the topic of the outcome, not as evidence that a formal equivalence criterion was met.
Precision and uncertainty. A confidence interval is a range of values compatible with the data under a statistical model and procedure; it communicates uncertainty around an estimate. It does not guarantee that the true value lies in the interval, and its interpretation depends on the analysis assumptions. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record. Without the outcome count and denominator, the precision of the observed agreement cannot be assessed.
Analysis plan and recalculation. The registry record lists no primary analyses. It does not report whether an adjusted analysis, a test of treatment order, or a specific method for paired binary observations was used. There is consequently no sponsor analysis to compare with a recalculation from posted summary statistics, and no recalculated result is stated. If the registry record does not give the underlying count and denominator, a simple unadjusted re-analysis cannot be independently reconstructed from the information recorded.
Planning calculations. A planning illustration is not an observed study result and is not evidence that a study had a particular probability of detecting an effect. The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. The record’s general note distinguishes participants per arm for non-time-to-event outcomes from total events for time-to-event calculations. These are planning conventions, not reported design justifications for this crossover study. The registry record does not report the trial’s own sample-size justification or an observed primary effect on which to base a trial-specific interpretation.
Over-dispersion and model choice. As a general statistical explanation, over-dispersion occurs when observed variation exceeds what a chosen model assumes. It can make standard errors too small if ignored, leading to intervals that are too narrow or tests that appear more decisive than warranted. This is a general consideration for count or binary data modeling, not a reported feature of these data. The registry record does not identify a fitted model or provide data with which to assess dispersion.
What the design description supports. The registry information supports a description of a randomized comparison of prescription determinations in a crossover sequence, with each lens worn bilaterally for a maximum of 15 minutes. It supports no particular inferential conclusion because the endpoint result and analysis are absent. Design labels describe how a study was organized; they do not substitute for estimates, uncertainty, or analysis details.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one outcome measure and no primary analyses. It does not report a multiplicity adjustment, a hierarchy of outcomes, or a strategy for controlling the chance of false-positive findings across multiple tests. With no reported primary analysis or result, the role of multiplicity in the actual inference cannot be assessed. The existence of one listed outcome measure does not establish that only one analysis was conducted.
The primary endpoint population is described as all completed subjects. Enrollment was 45, but the number of completed subjects contributing to the endpoint is not reported. The adverse-event entry gives 45 subjects at risk; that safety denominator should not be substituted for the missing primary endpoint denominator without confirmation that the populations coincide.
Missing-data methods are not reported in the registry record. It does not state whether any endpoint observations were missing, whether any participants withdrew, or how incomplete paired measurements were handled. In a crossover study, a participant may have information for one lens but not the other; as a general point, the handling of such incomplete pairs can affect the analysis population and estimate. There is no basis in the record to determine whether that situation occurred or how it was addressed.
The record does not describe an intention-to-treat, per-protocol, or other analysis population for the primary outcome. It also does not state whether exclusions were made after randomization. These omissions limit assessment of the population represented by any intended treatment comparison, quite apart from the absence of a posted endpoint result.
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 |
|---|---|---|---|
| All Subjects | 0 | 45 | 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 |
|---|---|
| All Subjects | 0 of 45 |
The adverse-event entry lists the group as “All Subjects.” It records 45 subjects at risk for serious adverse events and 0 affected, and 45 subjects at risk for other adverse events and 0 affected. These are registry counts for the recorded safety categories. The record does not list serious adverse-event terms.
The death count is not reported in the registry record. It should not be interpreted as zero. The available entry also does not give event definitions, collection procedures, observation duration for safety, or whether adverse events were assessed by lens sequence. Thus, the counts should be read as the safety information recorded, rather than as a complete account of every possible safety outcome or as a comparison establishing a difference between lenses.
As a general statistical point, zero recorded events does not prove that the underlying event risk is zero. The observed count is limited by the number of people assessed, the duration and intensity of observation, and how events were sought and recorded. This study describes brief lens wear, with each lens worn for a maximum of 15 minutes; the registry record does not provide additional safety follow-up detail. The counts do not address outcomes beyond the categories and period recorded.
12. What the Result Does, and Does Not, Mean
The registry record establishes the study question and the broad design: participants with astigmatism wore a new daily disposable etafilcon A toric lens and a marketed etafilcon A toric lens in randomized order, and the primary outcome concerned whether their prescriptions matched after 15 minutes of wear. It does not report the number of participants whose prescriptions matched, the completed-subject denominator, or an analysis of the comparison.
Accordingly, the record does not show how often exact prescription agreement occurred, how uncertain that estimate would be, or whether a prespecified equivalence criterion was satisfied. The word “equivalence” in the outcome title and the study’s stated purpose are not themselves results. No conclusion about the magnitude or statistical significance of a difference can be made from the endpoint description alone.
The outcome also has a specific scope. It concerns matching prescription determinations in the described brief wear assessment. It does not, on its own, measure longer-term wear, comfort, satisfaction, or other outcomes. Those outcomes are not reported in the registry record. Nor does the endpoint reveal the size or direction of any mismatches.
The safety entry records no serious or other adverse events among the listed subjects at risk, while the death count is not reported. Those recorded safety counts are separate from the unreported primary endpoint and should not be treated as evidence of prescription agreement.
The most defensible interpretation is therefore descriptive of the study’s design and intended measurement, not of its comparative result. The registry record does not provide enough primary outcome or analysis information to support a statistical conclusion about prescription equivalence.
13. Why This Trial Matters Statistically
This trial illustrates why an outcome’s name and a study’s objective are not interchangeable with a reported finding. The registry identifies prescription equivalence as the topic and defines a count of subjects with matching prescriptions. Without the observed count, denominator, and uncertainty, readers cannot assess how much agreement was observed or how precisely it was estimated.
It also highlights the distinction between agreement and formal equivalence. Exact matching is a clear endpoint definition, but a formal equivalence conclusion ordinarily depends on an acceptable difference specified in advance and an analysis that evaluates the data against that margin. The registry record does not describe such a margin or analysis. Statistical interpretation must follow the reported method and result, not the wording of the endpoint title alone.
The crossover design provides a useful setting for studying paired measurements because each participant wears both lenses. At the same time, understanding the analysis requires attention to order, period, and the handling of incomplete pairs. Those details are not reported in the registry record. The design label alone cannot establish that these considerations were addressed.
Finally, the record separates what is known from what is missing. It gives enrollment and safety counts, but the primary endpoint result is absent. A completed study can still have an incomplete public statistical record. Recognizing that distinction prevents enrollment or safety information from being mistaken for evidence about the primary comparison.
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 the primary outcome result. It gives neither the number of completed subjects with matching prescriptions nor the denominator used for the endpoint. No effect estimate, confidence interval, or p-value is reported, and no primary analysis is listed. The magnitude and precision of the comparison therefore cannot be evaluated.
The record does not report a formal equivalence margin or explain how equivalence was assessed. It also omits details about the statistical model, handling of paired binary outcomes, adjustment for sequence or period, and assessment of possible carryover. These omissions are especially relevant to interpreting a randomized crossover comparison, though the record does not establish that any particular bias occurred.
The endpoint population is described as all completed subjects, but the completion count, withdrawals, missing observations, and missing-data methods are not reported. The enrollment figure of 45 does not establish the number contributing to the primary endpoint. The safety denominator cannot be assumed to be the endpoint denominator.
Other procedural details are also absent, including who was masked, how masking was maintained, the randomization method, and whether a washout was used. The endpoint describes prescription matching after 15 minutes of wear, while broader outcomes and longer-term follow-up are not reported in the registry record. These limits restrict what can be inferred from the recorded study description, rather than demonstrating that the study procedures were inadequate.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Non-dispensing Study to Check Prescription Equivalence of Two Daily Disposable Toric Contact Lens Types — NCT01120782.
- Registry record last updated 2018-06-19; status last verified 2017-09.
- Results first posted 2011-12-08.
- 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
NCT01120782 is a completed, randomized, single-masked crossover study of two daily disposable etafilcon A toric contact lens types in people with astigmatism. Enrollment was 45. Participants wore both lens types in randomized order, with each lens worn bilaterally for a maximum of 15 minutes.
The primary endpoint was the number of completed subjects whose prescriptions were the same for both lenses after 15 minutes of wear. The registry record does not report the endpoint result, its denominator, or a statistical analysis. It does not report an equivalence margin or a formal equivalence conclusion.
The safety entry records 0 serious adverse events and 0 other adverse events among 45 subjects at risk in each category. The death count is not reported in the registry record. Overall, the record describes the question and design, but does not contain the primary result needed to assess prescription agreement statistically.