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 Prospective Study of Lens Performance of a Monthly Replacement Lens at Two Weeks and Four Weeks (NCT01293240), a na na study. The primary outcome is Overall Comfort.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01293240 |
| Phase | NA |
| Condition | Myopia, Astigmatism, Presbyopia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 117 |
| Arms in the primary outcome | n/a |
| Lead sponsor | CIBA VISION |
| Results posted | Yes |
2. Clinical Question
Population
The record identifies myopia, astigmatism, and presbyopia as the conditions of interest. Enrollment was 117. The primary outcome population was per protocol, with exclusions for reasons such as protocol deviations identified by masked review, discontinuations, and missing responses. Further eligibility details are not reported in the registry record.
Intervention
The device was a lotrafilcon B contact lens. The study purpose was to compare overall performance of a monthly replacement contact lens when worn for one month and when worn for two weeks. Additional details about the lens-wearing procedures are not reported in the registry record.
Comparator
The record describes a single-group study, not a randomized comparison. It does not identify a separate control arm or describe how observations at the two wear durations were paired or compared. The comparison intended by the study purpose should therefore not be read as evidence of randomized assignment to distinct groups.
Primary question
The primary measure was participant-reported overall comfort after two weeks, rated on a 10-point scale where 1 meant poor and 10 meant excellent. The registry record does not report the observed mean, standard deviation, number analyzed, or a numerical comparison between wear durations. Consequently, the direction and precision of the primary result cannot be determined from this record.
3. Trial Design
This was a prospective, completed, single-group device study sponsored by CIBA VISION. The registry lists enrollment of 117 and identifies the intervention as a lotrafilcon B contact lens. The study title and brief summary describe an intended comparison of lens performance at two weeks and four weeks, with the lens described as a monthly replacement lens. The record does not provide further details about the sequence of wear periods, participant assignment, or the operational meaning of the two wear durations.
Allocation is listed as NA, masking as NONE, and the model as SINGLE GROUP. The registry therefore does not describe random assignment or a masked comparison between treatment arms. Although the study purpose refers to comparing durations, the design information does not establish a separate randomized control group. The “arms” should not be interpreted as like-for-like randomized groups.
The primary outcome was overall comfort at two weeks. It was a participant-reported score collected through a questionnaire and described as a single retrospective evaluation of two weeks of wear. The analysis population was per protocol, with exclusions that could include protocol deviations determined through masked review, discontinuations, and missing responses. The number contributing to this primary analysis is not reported in the registry record.
The record lists 12 outcome measures and no analysis entries. It does not report a statistical analysis plan, a sample-size justification, interim analyses, or the detailed procedures used to compare the wear durations. The study is marked completed; the registry lists its start as 2010-12 and primary completion as 2011-04. Those administrative details do not supply the missing outcome estimates.
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 | Lotrafilcon B |
|---|---|
| STARTED | 117 |
| COMPLETED | 115 |
| NOT COMPLETED | 2 |
Reasons for not completing this period:
| Reason | Lotrafilcon B |
|---|---|
| Noncompliance | 2 |
Analysis population for the primary outcome, as defined in the registry: Analysis conducted per protocol, with exclusions due to reasons such as protocol deviations as determined by masked review; discontinuations; and/or missing responses.
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 | Lotrafilcon B |
|---|---|---|
| Participants analysed | 117 | |
| Age Continuous | years | 45.8 (SD 12.6) |
| Gender: Female | participants | 79 |
| Gender: Male | participants | 36 |
6. Primary Endpoint
The registry lists the primary outcome as Overall Comfort, measured over 2 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Units on a scale |
| Endpoint classification | Continuous Endpoint |
Overall comfort was the primary endpoint. Participants reported it on a questionnaire as a single retrospective assessment of two weeks of lens wear. The scale ran from 1, meaning poor, to 10, meaning excellent. The registry describes the outcome as a continuous measure and specifies that it would be summarized using a mean and standard deviation. The endpoint concerns the participant’s overall comfort judgment; it is not a direct measure of visual acuity, lens safety, or any other outcome unless separately specified elsewhere in the registry.
Comfort is relevant to a lens-performance study because it records the wearer’s own evaluation of the experience over the stated period. A retrospective rating combines the participant’s overall impression rather than reporting each moment of wear separately. As a general statistical point, a mean gives a central summary of scores, while a standard deviation describes how spread out individual scores are around that mean. Neither statistic alone shows how scores changed across wear durations or whether any difference is precise.
The endpoint description gives a two-week timeframe, while the study purpose also refers to performance after one month. The numerical primary endpoint result, the number of participants included in its analysis, and any estimate comparing the two durations are not reported in the registry record. Thus the endpoint’s definition is available, but its observed value and comparative interpretation are not.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record establishes what the primary outcome was intended to measure: participant-reported overall comfort after two weeks of wear, using a 10-point scale with 1 for poor and 10 for excellent. It also specifies a per-protocol analysis population and identifies a mean and standard deviation as the outcome summary. These details define the measurement and intended summary, but they do not reveal the observed comfort level.
The primary mean and standard deviation are not reported in the registry record. Nor does the record report a confidence interval, a p-value, a comparison estimate, or the number of participants included in the primary analysis. Without these values, readers cannot determine the average score, the variability between participants, the precision of an estimate, or the direction and magnitude of any comparison between two weeks and one month. No conclusion about the comparative result can be drawn from the endpoint definition alone.
The distinction between a study purpose and a reported statistical contrast matters. The stated purpose was to compare lens performance at two wear durations, but the design is listed as single group, with allocation NA and no masking. The record does not explain whether participants contributed observations at both durations, how a within-participant comparison was handled, or whether another comparison approach was used. It would be inappropriate to assume those details or to describe the study as a randomized comparison.
In general, a confidence interval communicates the range of estimates compatible with the data under the analysis assumptions, and its width indicates precision. A p-value addresses how compatible the observed data are with a specified null model; it does not state the probability that a treatment works. Neither type of result is reported for the primary endpoint in this record. The completed status does not substitute for those missing results.
The record lists 12 outcome measures, but no analysis entries. This does not establish that no analysis was performed; it means that analyses are not described in the registry record. The available information supports a description of the planned endpoint and the broad study structure, not a quantitative account of the outcome or a claim about how the two wear durations compared.
9. Statistical Methods Explained
What does a mean and standard deviation describe?
The primary endpoint is continuous and is specified as a mean with a standard deviation. In general, the mean summarizes the center of a set of scores, while the standard deviation describes the dispersion of individual scores around that center. A mean should be interpreted alongside its scale: in this study, the endpoints of the 10-point scale are defined as poor and excellent. The mean and standard deviation for the observed comfort scores are not reported in the registry record, so neither the central score nor the observed spread can be assessed.
A standard deviation is not the same as the standard error. In general, the standard deviation describes variability among observations, whereas the standard error describes uncertainty in an estimated quantity such as a mean. Confidence intervals are often used to express uncertainty around an estimate. Their interpretation depends on the analysis and its assumptions. The registry record does not report a standard error or confidence interval for overall comfort.
What would a comparison need to clarify?
The study purpose names two wear durations, while the design is listed as single group. A comparison might involve repeated observations from the same participants or some other structure, but the registry record does not say which. As a general principle, repeated measurements from one participant are related rather than independent. An analysis should account for that relationship if participants contribute measurements at more than one time or duration. The registry does not describe whether such measurements were collected or how any correlation was handled.
The record also does not give the numerical estimate of a contrast, its uncertainty, or a test result. Therefore, there is no basis in the registry record for explaining a particular model, test, adjustment, or comparison procedure as the one used. The existence of a stated study objective is not evidence that a specific statistical procedure was carried out or registered.
What do significance level and allocation assumptions mean?
The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. These assumptions describe a planning exercise, not the observed study design: the actual study is listed as single group, and allocation is NA. The illustration is not a sample-size justification for this trial and should not be read as observed power. No numerical planning counts or effect fractions are reported in the registry record.
In general, a two-sided significance level sets a threshold for evaluating data under a null hypothesis while allowing departures in either direction. Equal allocation is an assumption about how participants would be distributed between two arms in a hypothetical planning scenario. A normal approximation is a mathematical simplification used in some planning calculations. These assumptions do not show that the trial itself used two arms, had that allocation, or applied that approximation in its primary analysis.
Planning calculations based on an observed effect depend on the effect estimate used and on the assumptions chosen. A smaller target effect generally requires more information to detect with a given design and analysis, but the record does not provide the numerical effect fractions or planning results. Any sample-size figures associated with such an illustration are planning quantities, not actual enrollment outcomes and not evidence that the study had a specified probability of detecting its result.
Why does the analysis population matter?
The primary outcome is described as per protocol. The record says that exclusions could arise from protocol deviations determined by masked review, discontinuations, and missing responses. A per-protocol analysis focuses on participants meeting specified protocol conditions, but the complete criteria and the number retained are not reported in the registry record. The resulting estimate, if reported, would describe that analysis population rather than necessarily every enrolled participant.
As a general statistical concern, excluding participants after enrollment can affect interpretation if the reasons for exclusion are related to outcomes or differ across measurement periods. The direction and size of any such effect cannot be determined without counts, reasons, and outcome data. The record does not give a flow of participants through the analysis or describe a method for handling missing questionnaire responses.
Can the analysis assumptions be checked?
For continuous outcomes, statistical methods may rely on assumptions about the score distribution, independence or correlation of observations, and the way missing measurements are handled. These are general considerations rather than claims about the method used in this study. The registry record does not report diagnostic checks, model details, or sensitivity analyses. With no numerical endpoint summaries or analysis results, readers cannot evaluate the fit of assumptions or reproduce the primary comparison from the registry information.
10. Confidence Intervals for Each Arm
No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Lotrafilcon B | 112 | 8.600 | 1.400 | 8.338 to 8.862 |
R code and output
arm <- c("Lotrafilcon B")
n <- c(112)
m <- c(8.6)
sp <- c(1.4)
sd <- sp # posted standard deviations
for (i in seq_along(n)) {
se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}
CARM Lotrafilcon B 112 8.600 1.400 8.338 8.86211. Multiplicity, Missing Data and Analysis Populations
The registry lists 12 outcome measures and identifies overall comfort at two weeks as the primary endpoint. It does not describe a multiplicity strategy, such as adjustment for testing several outcomes, or specify whether secondary outcomes were arranged in a formal testing sequence. The analysis-entry count is zero. This means analyses are not listed in the registry record; it does not establish that no analyses were conducted.
As a general statistical issue, testing many outcomes can increase the chance of obtaining at least one apparently unusual result by chance if each is interpreted independently. A prespecified primary endpoint can help distinguish the main question from other outcomes, but the registry record does not report whether or how multiplicity was addressed. No individual secondary outcome results are included in the registry record for this account.
The primary analysis population is described as per protocol. Exclusions could involve protocol deviations identified by masked review, discontinuations, and missing responses. The registry record does not provide the exclusion counts, the number analyzed, the full per-protocol definition, or a participant flow. It also does not state whether missing questionnaire values were imputed, omitted, or handled using another method. The missing-data mechanism and the relationship between missing responses and comfort scores are not reported in the registry record.
These omissions limit assessment of whether the analyzed participants represent the enrolled group and how robust an estimate might be to missing responses. They also prevent comparison of analysis populations or sensitivity checks. No assumptions about the unreported procedures should be inferred from the study’s completed status or its stated outcome definition.
12. 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 |
|---|---|---|---|
| Lotrafilcon B | 0 | 117 | 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 |
|---|---|
| Lotrafilcon B | 0 of 117 |
The registry lists one lotrafilcon B group, with 117 participants at risk for serious adverse events and 0 affected. For other adverse events, it likewise lists 117 at risk and 0 affected. The reported serious adverse event terms list is empty. These are the counts recorded in the registry; they should be read as reported event counts for the categories shown, not as proof that every possible safety outcome was assessed or that no unlisted event occurred.
The deaths field has no numerical value. Deaths are therefore not reported in the registry record; a missing value should not be interpreted as a reported count of zero. The record does not give further detail about event definitions, collection procedures, or the period covered by these safety counts. It also does not provide a comparison group, so the figures do not support a between-group safety comparison.
In general, adverse-event counts are descriptive and depend on how events are defined, collected, and reported. The number at risk indicates the group size used for the registry’s count, but it does not by itself describe duration of exposure or completeness of follow-up. The posted figures should be interpreted within those limits and alongside the missing details in the registry record.
13. What the Result Does, and Does Not, Mean
The registry record establishes that a prospective, completed, single-group study evaluated a lotrafilcon B contact lens and had a stated purpose of comparing performance at two weeks and one month of wear. Its primary endpoint was participant-reported overall comfort after two weeks, on a 10-point scale ranging from poor to excellent. The record also describes a per-protocol analysis population and lists 117 enrolled participants.
These design and measurement details do not provide the primary result. The mean comfort score, standard deviation, analyzed sample size, and a numerical comparison are not reported in the registry record. There is no reported confidence interval or p-value for the primary outcome. As a result, the available information cannot establish how participants rated comfort on average, how much individual ratings varied, or how precisely any duration comparison was estimated.
The study’s stated comparison should not be mistaken for a randomized treatment contrast. The design is listed as single group, allocation as NA, and masking as NONE. Details of the actual comparison structure and analysis are not reported in the registry record. A planning illustration that assumes equal allocation between two arms is not evidence that this trial enrolled two randomized arms, and any planning sample sizes are not observed power.
The safety record lists zero participants affected by serious adverse events and zero affected by other adverse events among 117 at risk in the listed group. The deaths value is not reported. These entries are descriptive registry counts and do not fill the gap in the primary comfort results.
In general, statistical interpretation requires an estimate and information about its uncertainty, as well as an understanding of the analyzed population and methods. Here, the endpoint definition and broad design can be described, but the numerical effectiveness comparison cannot. No conclusion about whether comfort differed between the wear durations should be drawn from the information reported in the registry record.
14. Why This Trial Matters Statistically
This study is statistically informative as an example of the difference between a clearly named research objective and a fully interpretable reported result. The title and summary describe a comparison between two wear durations, while the listed model is single group and allocation is NA. That makes the structure of the intended contrast important: readers need to know whether observations came from the same participants at both durations or from another arrangement. The registry record does not supply that detail.
The primary measure is defined with useful specificity: participant-reported overall comfort, assessed retrospectively for two weeks of wear on a 10-point scale with stated endpoints. Yet a well-defined outcome is only one part of statistical interpretation. Without its mean, standard deviation, analyzed sample size, and an estimate of the intended comparison, readers cannot evaluate the observed level, variability, or precision.
The per-protocol population also matters. Excluding participants for deviations, discontinuations, or missing responses can shape which experiences contribute to a result. The registry identifies these possible exclusions but does not report their counts or the number included in the primary analysis. This illustrates why participant flow and missing-data procedures are not merely administrative details: they help readers judge what population an estimate represents.
Finally, the planning assumptions described for a hypothetical two-arm calculation are distinct from the single-group study design. Planning figures, even when based on an observed effect, are not observed power and do not replace a reported effect estimate with uncertainty. The record therefore supports discussion of endpoint definition, design labels, analysis-population limits, and safety counts, while leaving the core numerical comparison unresolved.
15. 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.
Several limitations specific to this record restrict interpretation. First, the study is identified as single group, with allocation listed as NA and masking as NONE, even though its purpose describes comparing wear durations. The registry record does not explain the comparison structure, whether observations at different durations came from the same participants, or how the contrast was estimated. A randomized comparison should not be inferred.
Second, the primary outcome is defined but its numerical results are absent. The registry record does not report the mean, standard deviation, number analyzed, comparison estimate, confidence interval, or p-value for overall comfort. The 10-point scale endpoints are specified, but no observed score distribution is available to assess.
Third, the primary analysis is per protocol, with potential exclusions for protocol deviations, discontinuations, and missing responses. The record does not give the numbers excluded for each reason, the full analysis criteria, or the handling of missing questionnaire responses. This limits assessment of selection and missing-data effects.
Fourth, the registry lists 12 outcome measures but no analysis entries. A multiplicity approach and detailed statistical analysis plan are not reported in the registry record. The planning description concerns a hypothetical equal-allocation two-arm setting and cannot establish the trial’s own design or analysis.
Finally, safety detail is limited to the listed adverse-event counts and an unreported deaths value. Event definitions, follow-up details, and further safety reporting are not present. These limitations mean the registry record is more informative about the study’s stated question and measurement than about its numerical findings.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Prospective Study of Lens Performance of a Monthly Replacement Lens at Two Weeks and Four Weeks — NCT01293240.
- Registry record last updated 2012-07-10; status last verified 2012-05.
- Results first posted 2012-06-01.
- 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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19. Record Summary
NCT01293240 is a completed prospective study sponsored by CIBA VISION. It enrolled 117 participants and evaluated a lotrafilcon B contact lens. The listed conditions are myopia, astigmatism, and presbyopia. The study purpose was to compare overall lens performance at two weeks and one month of wear. The design is listed as single group, allocation NA, and masking NONE.
The primary endpoint was participant-reported overall comfort after two weeks, assessed retrospectively on a 10-point scale from poor to excellent. Its analysis population was per protocol, with exclusions potentially involving protocol deviations, discontinuations, or missing responses. The registry lists 12 outcome measures and no analysis entries.
Numerical primary results and the comparison method are not reported in the registry record. The listed group had 0 serious adverse events and 0 other adverse events among 117 at risk; deaths are not reported.