Clinical Evaluation of Lapsed Contact Lens Wearers Who Are Re-fit Into Senofilcon A Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of Lapsed Contact Lens Wearers Who Are Re-fit Into Senofilcon A Contact Lenses (NCT01990664), a randomized na study. The primary outcome is Proportion of Successfully Re-fitted Subjects.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group, open-label, multi-center clinical evaluation. Masking is listed as none. The listed device interventions are senofilcon A and senofilcon A for Astigmatism, while the arm titles identify Control (Senofilcon A) and Test (Senofilcon A). Both arm descriptions say that lenses were to be worn in a daily wear modality. The brief summary describes spherical and toric designs and a duration of approximately four weeks. The primary outcome timeframe is 4 weeks.

The registry enrollment field reports 199. The brief summary separately states that the total number of subjects was 200. These figures are not reconciled in the registry record, so they should not be treated as interchangeable descriptions of the analysis population. The endpoint data give group sizes of 93.0 for the control arm and 76.0 for the test arm. The primary endpoint population is defined as subjects completing all study visits without a major protocol deviation; the record does not report how that definition relates to all enrolled or randomized subjects.

The study status is completed. The recorded start is 2013-11 and primary completion is 2014-04. The phase entry is NA. The registry names Johnson & Johnson Vision Care, Inc. as sponsor. The record does not state the randomization method, allocation concealment procedures, number or locations of centers, or whether anyone involved in outcome assessment was kept unaware of group assignment. Those details are not reported in the registry record.

The control and test arm labels do not fully clarify the contrast: both include Senofilcon A, while the listed interventions distinguish Senofilcon A and Senofilcon A for Astigmatism. The record therefore supports describing the comparison using its recorded arm titles, but not inferring a more specific contrast than the arm descriptions establish. This matters when interpreting an observed group difference, because it is not possible from the record alone to attribute that difference to a particular lens feature.

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: A total of 199 subjects were enrolled in the study; 7 subjects were enrolled but not randomized. 18 subjects were discontinued and 174 subjects completed the study. Of those 174 completed subjects, 5 subjects had major protocol deviations; 169 subjects were included in the analysis.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The analysis population includes all subjects who have completed all study visits without a major protocol deviation.

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: The analysis population consists of all subjects that were enrolled into the study

6. Primary Endpoint

The registry lists the primary outcome as Proportion of Successfully Re-fitted Subjects, measured over 4 weeks.

The primary endpoint is the proportion of lapsed contact lens wearers judged successfully refitted. The registry defines the relevant lapse as stopping contact lens use more than 6 months before the date of enrollment. Success was based on an eye care practitioner’s judgment of acceptable physiology. The outcome is recorded as a percentage of subjects, with a timeframe of 4 weeks.

A proportion is useful for this question because it expresses how often a specified binary outcome—successful refitting—was observed in each arm. It can be compared across groups without implying that all participants had the same experience beyond the success criterion. The endpoint is clinically interpretable in that it represents a practitioner’s assessment of whether the fit was acceptable at the evaluation, but it is not a direct measure of comfort, continued wear, preference, or use beyond the stated timeframe. Those outcomes are not reported as secondary results in the registry record.

The analysis population is defined as subjects who completed all study visits without a major protocol deviation. This definition makes clear that the primary proportion is not explicitly described as an all-randomized analysis. The registry does not report the number of participants who failed to complete visits, had major deviations, or were otherwise omitted. The endpoint should therefore be read as a result for the stated analysis population, with the relationship to all enrolled participants left unclear.

7. Results Posted in the Registry

• Test (Senofilcon A): 96.1% (73/76) versus 100.0% (93/93) on control; risk difference -3.9 percentage points (95% CI -8.3 to 0.4), risk ratio 0.96 (0.92–1.01); unadjusted two-proportion z-test p = 0.053.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary at the participant level: a subject is classified as successfully refitted or not under the recorded definition. A percentage summarizes the number classified as successful relative to the number in the endpoint group. For this study, the registry reports 100.0% in the control arm and 95.52% in the test arm. A percentage is easy to interpret, but it does not convey uncertainty on its own; the group sizes and the comparison interval add information about how precisely the proportions and their contrast are estimated.

What does the risk difference describe?

The risk difference is the test-arm event probability minus the control-arm event probability. The recalculated unadjusted estimate is -0.040, with a confidence interval from -0.083 to 0.004. A negative value means the observed proportion was lower in the test arm than in control. The interval includes zero, which represents equal probabilities, and also extends to values on the other side of zero. It therefore does not isolate a single direction or exact size of difference with high precision. The estimate is an absolute contrast, not a ratio.

What does the relative risk add?

The relative risk compares the test-arm probability with the control-arm probability as a ratio. The recalculated estimate is 0.961, with a confidence interval from 0.918 to 1.005. A ratio of 1 represents equal probabilities. Because the interval includes 1, it is compatible with equality as well as with relative differences on either side. Relative and absolute scales answer related but different questions. A ratio describes proportional change between probabilities, while a risk difference describes their separation on the probability scale. For a common outcome such as successful refitting in these groups, it is useful to consider both scales rather than relying on one alone.

How should the p-value be read?

The unadjusted p-value is 0.053. In general, a p-value describes how unusual data at least as discrepant as those observed would be under a statistical model that assumes no group difference. It is not the probability that the no-difference assumption is true, nor does it measure the probability that a result occurred by chance in a literal sense. It also does not quantify clinical importance. A value near a conventional cutoff does not create a sharp distinction between a meaningful finding and an uninformative one. Here, the p-value should be read alongside the estimated risk difference and its interval, rather than as a stand-alone verdict.

What does recalculated mean in this comparison?

The displayed comparison is a simple unadjusted recalculation from the posted summary statistics. It is not presented as the sponsor’s own analysis. The registry reports zero analyses, and the record does not supply a sponsor-reported effect estimate or inferential result for this endpoint. Thus the recalculation can help readers understand the posted group summaries, but it does not establish which analytic model, covariate adjustment, or testing procedure the study team used. A statistical analysis plan is not reported in the registry record.

Why do analysis populations matter?

The primary endpoint description restricts the analysis population to subjects who completed all study visits without a major protocol deviation. In general, an analysis restricted this way can differ from an analysis that retains everyone randomized, because eligibility for the endpoint analysis depends on completion and protocol adherence after assignment. The registry does not report the number excluded under this rule, the reasons for exclusion, or how missing endpoint observations were handled. It is therefore not possible to assess from the record whether the reported groups fully reflect the randomized groups or whether missingness could have affected the proportions.

What do the planning assumptions represent?

The registry’s planning description characterizes sample-size calculations as illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It describes varying the effect to detect as a stated fraction of the observed effect. These are planning assumptions, not evidence about the trial’s actual design rationale. No sample-size illustration results are reported in the registry record, and the record does not state that the trial was planned around the observed effect. Any sample-size value based on such assumptions is a planning illustration, not observed power or a measure of how likely the trial was to detect a real effect.

In general, power is a design property under specified assumptions about the effect, variability, significance level, allocation, and analysis. It cannot be inferred from the observed p-value, and a post hoc calculation using the observed effect does not establish the probability that the study detected a real difference. The record does not report a sample-size justification, planned power, interim analyses, or a prespecified statistical plan. Those aspects of the trial’s conduct and analysis are not reported in the registry record.

Why might over-dispersion matter for other outcomes?

General statistical context: over-dispersion occurs when observed variability is greater than a model assumes. It can make standard errors too small if the model’s variance assumptions are not appropriate, leading to confidence intervals that are too narrow and tests that overstate the evidence. The primary endpoint is a binary proportion, and no over-dispersion parameter is reported. This concept is relevant to count or clustered outcomes in general, but the registry does not provide a model specification that would support a claim that over-dispersion was assessed or present in this study.

Overall, the methods that can be described from the record are limited to a randomized parallel design, an endpoint defined by practitioner judgment, and an unadjusted recalculation of the posted summary statistics. Details of random sequence generation, concealment, modeling, adjustment, missing-data handling, and multiplicity procedures are not reported in the registry record. These omissions limit reconstruction of the study’s original inferential approach.

10. Confidence Intervals and Precision

The confidence interval for the recalculated risk difference extends from -0.083 to 0.004. In general, a confidence interval describes a range of effect estimates compatible with the observed data under a specified statistical method. It is not a guarantee that the true effect lies in the interval, and it does not express the probability that any particular effect value is correct. Here, the interval includes zero, so the data are compatible with no difference in the underlying proportions under the method used. It also includes values indicating a negative difference and a small positive difference.

The interval’s span indicates that the exact size of the difference is not pinned down precisely. The point estimate is -0.040, but the plausible values represented by the interval cover a wider range, including no difference. The relative-risk interval, from 0.918 to 1.005, similarly includes 1. Because both intervals include their respective no-difference values, neither supports a sharply determined direction of effect. This is not proof that the two arms are equivalent: equivalence requires a prespecified margin and an analysis designed to assess whether the interval lies within that margin. Such a margin and analysis are not reported in the registry record.

The intervals are recalculated from the posted summary statistics, rather than reported as a sponsor analysis. The registry does not specify a statistical analysis plan or the interval method used by the study team. Precision should therefore be interpreted as a property of the recalculated summary, not as confirmation of a prespecified sponsor method. The group endpoint sizes are 93.0 and 76.0, but the record does not report how exclusions or missing observations affected those sizes.

Confidence intervals also do not address every source of uncertainty. They quantify sampling uncertainty under the calculation’s assumptions, but do not account automatically for possible selection from the completer-based analysis population, unmasked practitioner assessment, or uncertainty about the exact contrast between the arm descriptions. Those issues require design and reporting details that are not reported in the registry record.

11. Multiplicity, Missing Data and Analysis Populations

The registry reports one outcome measure and zero posted analyses. It also reports zero secondary results. A single listed primary outcome may reduce concern about selective emphasis among multiple reported endpoints, but the registry record does not establish that no additional outcomes were collected, tested, or considered. It also does not report whether more than one statistical test was conducted for the primary endpoint. A multiplicity adjustment, if any, is not reported in the registry record.

The primary analysis population is described as subjects completing all study visits without a major protocol deviation. The registry does not report how many randomized subjects did not complete visits, how many had major deviations, or whether any endpoint observations were missing. The methods used to handle missing data are not reported in the registry record. It is not stated whether missing outcomes were excluded, imputed, or handled by another approach. The reported arm denominators should therefore be read as the endpoint group sizes, without assuming that they include every randomized participant.

The enrollment field reports 199, whereas the brief summary states a total of 200 subjects. The record does not explain this difference. It also does not reconcile these descriptions with the endpoint group sizes. No total should be inferred from those group sizes, and the available information is insufficient to determine how enrollment, randomization, follow-up, and analysis populations relate to one another.

The registry does not report interim analyses, stopping rules, a prespecified statistical analysis plan, or the approach to protocol deviations beyond the endpoint population definition. Their presence or absence cannot be inferred from the completed status. The recalculated comparison is unadjusted and should not be read as evidence that the original study analysis used the same method or testing strategy.

12. 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.

The registry lists zero serious adverse events and zero other adverse events in the control group, with 102 at risk in each category. It also lists zero serious adverse events and zero other adverse events in the test group, with 90 at risk in each category. The serious adverse event terms list is empty. These entries describe what was recorded in the adverse-event fields; they do not establish that no adverse experiences of any kind occurred outside the recorded categories or reporting process.

Deaths are recorded as null for both groups. A null entry is not the same as a reported count of zero, so the record does not report a death count. The adverse-event denominators differ from the primary endpoint group sizes, and the registry does not explain their relationship to the endpoint population, randomization, or follow-up. They should not be substituted for the endpoint denominators.

In general, observing zero events does not prove that the underlying event risk is zero. The meaning of a zero count depends on how events were defined, collected, monitored, and reported, as well as on the amount of observation. The registry does not provide event definitions, collection procedures, severity breakdowns beyond the serious and other categories, or follow-up detail for safety. The reported zeros should therefore be described narrowly as the recorded adverse-event counts, without a broader safety conclusion.

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

The posted endpoint results show successful refitting recorded for 100.0% of the control arm and 95.52% of the test arm, using the endpoint population defined in the registry. The recalculated unadjusted risk difference is -0.040, with a confidence interval from -0.083 to 0.004; the unadjusted p-value is 0.053. The relative-risk estimate is 0.961, with a confidence interval from 0.918 to 1.005. These estimates describe the observed group comparison and its uncertainty. They do not establish a definitive difference or prove that the arms are equivalent.

The endpoint captures a practitioner’s assessment of acceptable physiology at the 4 weeks timeframe. It does not, on its own, establish comfort, satisfaction, sustained lens use, preference, or outcomes beyond that timeframe. Such results are not reported in the registry record. The open-label design and the practitioner-judged endpoint are relevant context, especially because masking of outcome assessment is not reported.

The results should not be extended beyond the population and endpoint actually described. The record concerns lapsed wearers who stopped contact lens use more than 6 months before enrollment, and the endpoint analysis is restricted to subjects who completed all study visits without a major protocol deviation. The relationship of that group to everyone randomized is not reported. The record also leaves unclear the precise distinction between the control and test arm descriptions, which both name Senofilcon A, while the intervention list includes Senofilcon A for Astigmatism.

The comparison was recalculated from posted summary statistics, and the registry reports no analyses. It is therefore a useful statistical interpretation of the listed counts and proportions, not a substitute for a sponsor-reported analysis or a prespecified analysis plan. No conclusion about treatment benefit, clinical advice, or longer-term performance follows from these registry results alone.

14. Why This Trial Matters Statistically

This trial illustrates why a high observed proportion in both groups does not, by itself, settle the comparative question. The relevant statistical information includes the absolute difference, the relative comparison, and the uncertainty around each estimate. Here, the recalculated risk-difference interval includes zero, and the relative-risk interval includes 1. Those features make the uncertainty visible and discourage treating the point estimates as exact or definitive.

It also shows the importance of interpreting outcome percentages alongside the population used to calculate them. The primary endpoint is defined for subjects completing all study visits without a major protocol deviation, but the record does not report how this group relates to all randomized participants. The enrollment field and the brief summary also give different totals—199 and 200—and do not explain the discrepancy. Such reporting gaps matter because group percentages are meaningful only in relation to their denominators and the process that determined inclusion.

The study uses a practitioner-judged endpoint in an open-label design. Statistical interpretation cannot remove the possibility that assessment procedures or knowledge of group assignment influenced judgment; the registry does not report masking or standardized assessment details. Nor does the endpoint cover every outcome relevant to lens use. The distinction between a short-term fitting assessment and longer-term experience is important when considering what the proportion can represent.

Finally, the record provides limited information about the original statistical plan. The recalculated result is unadjusted, while the registry lists no analyses. This makes it especially important to distinguish a transparent re-analysis of posted summary data from a prespecified trial analysis. The example demonstrates how effect estimates, uncertainty, analysis-population definitions, and reporting limitations all contribute to a careful reading of a clinical result.

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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The registry record leaves important details of the group contrast unclear. Both arm titles refer to Senofilcon A, while the intervention list includes Senofilcon A and Senofilcon A for Astigmatism. The brief summary mentions spherical and toric designs, but the arm descriptions only specify daily wear. Without a clearer explanation of what differed between arms and how lens designs were assigned, the observed comparison cannot be attributed to a specific design feature based on this record alone.

The endpoint depends on an eye care practitioner’s judgment of acceptable physiology, and the study is listed as unmasked. The registry does not report whether assessment criteria were standardized, whether assessors knew group assignment, or how disagreements or borderline assessments were handled. The outcome may be relevant to fitting, but it is not described as a masked or fully objective measure.

The endpoint population is restricted to participants who completed all study visits without a major protocol deviation. The number excluded under this definition, the reasons for exclusion, and the handling of missing endpoint data are not reported in the registry record. This prevents assessment of how much the endpoint results may depend on follow-up completion or protocol adherence. The record also reports enrollment 199 in one field and a total of 200 subjects in the brief summary, without reconciliation.

The reported primary timeframe is 4 weeks, and the record does not provide longer-term outcomes. There is one listed outcome measure, no posted analyses, and no secondary results. A statistical analysis plan, multiplicity approach, interim analysis information, sample-size justification, and randomization procedures are not reported. These limitations constrain assessment of the original analysis and of how broadly the short-term practitioner-judged result can be interpreted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Evaluation of Lapsed Contact Lens Wearers Who Are Re-fit Into Senofilcon A Contact Lenses — NCT01990664.
• Registry record last updated 2018-06-19; status last verified 2016-01.
• Results first posted 2016-02-25.
• 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.

19. Record Summary

The registry describes a randomized, open-label, parallel, multi-center evaluation of lapsed contact lens wearers refitted with senofilcon A lenses. The primary endpoint was the percentage judged successfully refitted at 4 weeks, based on an eye care practitioner’s judgment of acceptable physiology. The endpoint population comprised subjects who completed all study visits without a major protocol deviation.

Successful refitting was recorded for 100.0% of the control arm and 95.52% of the test arm. The recalculated unadjusted risk difference was -0.040, with a confidence interval from -0.083 to 0.004 and an unadjusted p-value of 0.053. The relative-risk estimate was 0.961, with a confidence interval from 0.918 to 1.005. These intervals include the values corresponding to no group difference.

The registry lists no analyses and no secondary results. It reports zero serious and other adverse events in the recorded groups, while death counts are null. Enrollment is listed as 199, and the brief summary states 200 subjects; the difference is not explained in the registry record. Several design, analysis, missing-data, and follow-up details are also not reported.