Clinical Evaluation of Two Monthly Replacement Silicone Hydrogel Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of Two Monthly Replacement Silicone Hydrogel Contact Lenses (NCT01629693), a randomized na study. The primary outcome is Change From Baseline in Likert Response: "I Can Comfortably Wear my Lenses" at Day 30.

2. Clinical Question

The trial asked whether comfort ratings at the end of a month differed between two silicone hydrogel contact lenses in habitual daily-wear users who experienced symptoms with soft contact lenses. The registry describes comfort as a participant-reported experience, rather than an objective measure of lens performance. Its stated focus was the response to the question about being able to wear the lenses comfortably.

This is an active comparison: the registry describes two lens products, rather than a lens group and a no-lens control group. The outcome is specific to participants’ reported comfort under the study’s wearing schedule. It should not be taken as a measure of every aspect of lens use or as a result for people outside the described study population.

3. Trial Design

The study was randomized and used a parallel-group design. Participants were assigned to Air Optix or Biofinity, and each group used its assigned lens during the study. The record describes the trial as single masked, but does not report who was masked or how masking was maintained. It does not describe the randomization sequence or allocation concealment.

The registry lists an enrollment of 398 and a completed status. The study start is recorded as 2013-07, and primary completion as 2013-11. The sponsor was Alcon Research. The phase is listed as NA. Myopia and astigmatism are the conditions named in the record; those entries alone do not establish that every participant had both conditions.

Both groups followed the same stated daily-wear schedule. Each lens was worn bilaterally, meaning in both eyes, for at least 4 hours a day, 5 days a week, for 4 weeks. Participants removed the lenses nightly for cleaning and disinfection. The study therefore compared the assigned lens products under a specified wearing routine; the record does not describe a comparison of different wearing schedules.

The primary outcome timeframe is baseline and Day 30. The stated analysis population includes participants who completed the protocol and had no major protocol violations. The registry does not report how many enrolled participants met those conditions, how many were assigned to each group, or how many contributed primary outcome data. Enrollment should therefore not be read as the number analyzed for the comfort outcome.

The record lists one outcome measure and no analysis entries. It does not give an outcome estimate, a between-group comparison, or a statistical analysis plan. The completed status indicates the trial’s recorded status, but by itself does not supply results or explain how the trial was conducted beyond the design details described in the 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.

Before assignment: Of the 398 enrolled, 17 participants were exited as screen failures. This reporting group includes all participants who provided informed consent, were randomized, and utilized the study lenses (381).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: This analysis population includes all participants who completed the protocol and had no major protocol violations.

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.

Population: This analysis population includes all randomized participants who utilized the study lenses.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Likert Response: "I Can Comfortably Wear my Lenses" at Day 30, measured over Baseline, Day 30.

The primary endpoint is the change from baseline in the participant’s response to the statement, “I can comfortably wear my lenses,” at Day 30. The response used a 10-point Likert scale, with 1=poor and 10=excellent. The record identifies the endpoint as a mean and lists standard deviation as its measure of dispersion.

A participant-reported comfort measure is relevant to a study whose stated purpose is to evaluate comfort near the end of the monthly replacement period. It captures the participant’s own assessment of wearing comfort, which may not be represented by a physical or clinical measurement alone. The endpoint is specific to the wording of the question, the response scale, and the assessment times stated in the registry.

Change from baseline is intended to describe how the response at follow-up relates to the initial response. The registry gives the endpoint title and assessment timeframe, but does not report the actual group means, the change estimates, or the calculation convention used for change. In particular, the direction in which the change was calculated is not specified. The scale anchors identify the meaning of the response values, but the registry record does not establish that equal steps on the scale correspond to equal changes in comfort for every participant.

No numerical primary-outcome result is reported in the registry record. It is therefore not possible from that record to describe the size or precision of either group’s change, or the difference between groups.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is continuous in the sense that the record summarizes it using a mean and standard deviation, although the underlying response is recorded on a 10-point Likert scale. A mean can summarize the central tendency of responses across participants. A standard deviation describes how dispersed those responses are around the mean. Both statistics would be needed to understand the group-level pattern and variation, but neither is reported for the primary outcome in the registry record.

What would a between-group estimate describe?

For a randomized comparison, the central statistical question is whether the change in comfort differs between the assigned groups. A between-group estimate would quantify that contrast using the analysis defined for the endpoint. It would be more informative than considering each group’s change in isolation: a change within one group does not by itself show that the change differs from the other group’s change. The registry record does not report such an estimate or specify the exact comparison method.

The endpoint title says “Change From Baseline,” and the timeframe is baseline and Day 30. The record does not say whether the calculation was Day 30 minus baseline or used another convention, nor does it specify whether the comparison used changes, follow-up values adjusted for baseline, or another approach. These choices can affect the interpretation of an estimate. They should not be inferred from the endpoint title alone.

How should uncertainty be understood?

In general, a confidence interval expresses uncertainty around an estimate under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, while the interval’s location indicates which effect sizes are compatible with the data and model. A p-value, in general, measures how unusual the observed data would be under a specified null hypothesis and statistical model. It does not give the probability that a treatment effect is true, and it is not a measure of the size or importance of an effect. No confidence interval or p-value for comfort is reported in the registry record.

Randomization is intended to make assigned groups comparable on average, but the record does not describe the sequence-generation method or allocation concealment. The term single masked is recorded, but who was masked and how masking was implemented are not reported. These details can inform assessment of possible bias in assignment, outcome reporting, and conduct; they cannot be filled in from the design labels alone.

What do the planning illustrations represent?

The planning illustrations use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. They are described as illustrations based on the observed effect, with the effect to detect expressed as a fraction of that observed effect. For non-time-to-event outcomes, the intended quantity is participants per arm for a stated power level. These are planning calculations, not the trial’s own design justification and not observed power. The registry record does not report the trial’s sample-size justification or provide numerical primary-outcome results from which to assess the observed effect directly.

In general, sample-size planning depends on the target effect, variability, significance level, desired power, allocation, and analysis assumptions. A planning illustration answers a conditional question: how much information might be needed under its assumptions to detect a specified effect. It does not show whether the trial actually achieved that power, and it does not establish what the trial found. No sample-size justification from the investigators is reported in the registry record.

Why can over-dispersion matter?

As a general concept, over-dispersion occurs when data vary more than a statistical model assumes. If a model understates the variability, its standard errors and uncertainty intervals may be too small, making evidence appear more precise than it is. The primary endpoint is reported as a mean with standard deviation, but the registry record does not describe a model, a variance assessment, or any adjustment for over-dispersion. This concept therefore explains a general modeling concern; it is not a finding about this trial.

Other methodological details are also absent. The record does not report the statistical model, covariates, handling of repeated observations, missing-data approach, or sensitivity analyses. The baseline and Day 30 timeframe suggests repeated measurement of comfort, but it does not establish how those observations were incorporated in an analysis. Nor does the record state whether the primary comparison was adjusted for any baseline characteristics.

The record lists one outcome measure, while its reporting note says that the primary outcome has several categories or time points and was not reduced to one comparison. This leaves the outcome’s result structure unclear. Without results for the relevant categories or times, and without a defined comparison, there is no single numerical estimate to interpret. The registry record also gives no multiplicity adjustment or testing hierarchy. In general, testing multiple outcomes, times, or categories can increase the chance of finding a nominally notable result by chance, so the analysis plan is important to interpretation.

The serious adverse event counts are descriptive safety summaries, not a substitute for a model-based comparison. The record gives at-risk counts and affected counts for each group, but does not describe inferential comparisons or provide detail on event timing, severity beyond the serious classification, or attribution. No inferential safety analysis is reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, the change in the comfort response from baseline to Day 30. Its reporting note also states that the primary outcome has several categories or time points and was not reduced to one comparison. The record does not explain which categories or times are involved, how they relate to the stated baseline and Day 30 timeframe, or which comparison was intended to be primary. It therefore does not provide a single numerical primary-outcome result for interpretation.

Multiplicity refers, in general, to the statistical issue created when multiple outcomes, time points, categories, or comparisons are tested. Without a prespecified testing strategy, considering many results can increase the chance that at least one appears notable by chance. The registry record does not report a multiplicity adjustment, a hierarchy of tests, or an analysis plan that would clarify how multiple results were to be interpreted. No specific correction or testing procedure should be assumed.

The stated primary analysis population consists of protocol completers without major protocol violations. This is a population definition, but the record does not report its size or how many participants were excluded for each reason. It also does not report participant flow by group or the number with available baseline and Day 30 responses.

Missing-data handling is not reported in the registry record. There is no description of imputation, use of available observations, or sensitivity analysis for missing comfort responses. Consequently, the potential influence of incomplete follow-up on the primary outcome cannot be assessed from this record. The enrollment count should not be treated as the analysis denominator.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: chest pain (0.5%), acanthamoeba keratitis (0.5%).

The registry reports one serious adverse event among 193 participants at risk in the Air Optix group and one among 188 participants at risk in the Biofinity group. It reports zero other adverse events in each group. These are counts as recorded, not a complete account of every possible safety outcome or a basis by themselves for a comparative safety conclusion.

The serious-event terms listed are Chest pain at 0.5% and Acanthamoeba keratitis at 0.5%. The record does not assign those listed terms to a specific group in the information presented, so they should not be attributed to Air Optix or Biofinity. The registry also does not describe event timing, relatedness to the lens, or additional clinical context for those terms.

Deaths are not reported in the registry record. A missing death value should not be interpreted as evidence that no deaths occurred. The at-risk counts and affected counts give a limited descriptive view of the posted safety data; the record does not report an inferential comparison or enough detail to evaluate differences in risk. These safety figures should be read separately from the unreported primary comfort results.

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

The registry record establishes that a randomized, single-masked, parallel-group trial compared Air Optix and Biofinity lenses in habitual daily-wear symptomatic soft contact lens wearers. It specifies a bilateral daily-wear schedule and identifies a participant-reported comfort change from baseline to Day 30 as the primary outcome. It also reports serious adverse event counts for the two groups.

It does not report the numerical comfort results. There is no reported mean change for either group, no between-group estimate, and no measure of uncertainty for that comparison. The record therefore cannot establish the direction or size of a difference in comfort, or how precisely any difference was estimated. A completed study status and an enrollment count do not supply those missing outcome results.

The endpoint concerns responses to a particular comfort statement on a 10-point scale. Even if numerical results were available, they would need to be interpreted in relation to that question, the study population, the wearing schedule, and the stated analysis population. The registry record does not report enough detail to extend any possible result to other lens types, schedules, populations, or outcomes.

The serious adverse event counts are descriptive. The record does not provide context sufficient to establish causation, compare event risk with precision, or assign the listed serious-event terms to an arm. The reported counts do not resolve the missing primary comfort comparison.

These boundaries are important: the registry supports a description of what was planned and which limited safety figures were posted, but it does not support a numerical conclusion about comparative comfort. General statistical ideas such as confidence intervals and multiplicity can explain how results would be assessed, but they cannot replace the absent estimates or analysis details.

13. Why This Trial Matters Statistically

This trial illustrates the difference between a clearly named endpoint and a reportable result. The registry identifies a participant-reported comfort question, its scale anchors, and its assessment timeframe. Those details help readers understand what investigators intended to measure. Without the group summaries and comparison, however, the endpoint description does not answer the statistical question about comparative change.

It also illustrates why the analysis population matters. The stated population includes protocol completers without major violations, while enrollment refers to all participants enrolled. Those are not interchangeable quantities. Without participant flow, analysis denominators, or missing-data information, readers cannot judge how closely the analyzed group represents the randomized participants or how much incomplete follow-up may matter.

The record’s note that the outcome has several categories or time points, but was not reduced to one comparison, highlights the importance of defining the analysis target. A clear plan identifies which outcome, time, and contrast carries the primary interpretation and how other results will be handled. The registry does not report those details or a multiplicity strategy.

Finally, planning calculations and observed trial results answer different questions. Planning illustrations based on an effect and assumptions do not demonstrate that the trial had a particular observed effect or precision. Likewise, enrollment alone does not show how informative the primary outcome data were. For this record, the key statistical lesson is that design and endpoint information can be described, while the comparative comfort result remains unavailable in the registry record.

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 does not report numerical results for the primary comfort endpoint. Group means, standard deviations, changes, a between-group estimate, confidence intervals, and p-values are not reported. The primary result therefore cannot be quantified from this record.

The outcome reporting is also unclear. One outcome measure is listed, while the registry note says that the primary outcome has several categories or time points and was not reduced to one comparison. The record does not explain those categories or times or identify a single contrast. This makes it difficult to determine what result would directly answer the stated study question.

The analysis population is defined as protocol completers without major protocol violations, but its size and group composition are not reported. Participant flow, exclusions, missing responses, and the handling of missing data are also not reported. Thus, the extent to which the analysis population differs from those enrolled or randomized cannot be assessed.

Important design and analysis details are absent. The record does not identify who was masked, describe the randomization procedure or allocation concealment, or report the statistical model, baseline adjustment, repeated-measures handling, multiplicity strategy, or sensitivity analyses. It also does not report the investigators’ sample-size justification.

The safety information is limited to posted counts, at-risk numbers, and two serious-event terms with percentages. The record does not identify the group for each term or report additional event context, and deaths are not reported. These limitations constrain interpretation of safety as well as efficacy, without establishing that any particular bias or problem occurred.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Evaluation of Two Monthly Replacement Silicone Hydrogel Contact Lenses — NCT01629693.
• Registry record last updated 2014-11-06; status last verified 2014-10.
• Results first posted 2014-11-06.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT01629693 is a completed randomized, single-masked, parallel-group trial sponsored by Alcon Research. The registry records enrollment of 398, a start of 2013-07, and primary completion in 2013-11. It compared bilateral daily wear of Lotrafilcon B (Air Optix) with Comfilcon A (Biofinity) for the stated schedule of at least 4 hours a day, 5 days a week, for 4 weeks.

The primary endpoint was change from baseline to Day 30 in a participant response to “I can comfortably wear my lenses,” rated on a 10-point scale from 1=poor to 10=excellent. The stated analysis population was protocol completers without major violations. Numerical primary-outcome results and analysis details are not reported in the registry record.

The record reports one serious adverse event in each group, no other adverse events in either group, and the serious-event terms Chest pain and Acanthamoeba keratitis at 0.5% each. It does not assign those terms to a group. Deaths are not reported in the registry record.