DAILIES TOTAL1® Lens Centration in a Japanese Population: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for DAILIES TOTAL1® Lens Centration in a Japanese Population (NCT02252133), a randomized na study. The primary outcome is Success Rate of Lens Centration After 7 ± 2 Days of Wear.

2. Clinical Question

3. Trial Design

This was a randomized, open-label crossover study. Its official title describes it as a pilot evaluation of DAILIES TOTAL1® lens centration in a Japanese population. The registry lists the study as completed, with an enrollment of 53. The recorded start was 2014-10, and primary completion was 2014-11. The phase is listed as NA, and Alcon Research is the sponsor.

In a crossover design, participants receive more than one study condition in sequence. In this study, the two products were worn in opposite orders: DT1 followed by 1DAVTE, or 1DAVTE followed by DT1. The sequences were randomized. The arm descriptions state that each product was worn bilaterally for 7 days on a daily-wear, daily-disposable basis. The stated purpose was to compare centration after 7 ± 2 days of wearing each product.

Because participants used both products, the design differs from a parallel-group trial in which each participant receives only one treatment. General statistical interpretation of crossover data needs to account for the fact that observations from the same participant are related, and may also need to consider sequence or period effects. The registry record does not report the analysis model or explain how these design features were handled in the primary comparison.

Masking is listed as none. The outcome was assessed by an investigator during slit-lamp examination, so the record does not indicate that the assessor was masked to the product. It also does not report details about allocation concealment, the randomization procedure, a washout period, or whether any carryover assessment was performed. Those details should not be inferred from the crossover label alone.

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 53 enrolled, 6 subjects were exited as screen failures prior to randomization. This reporting group includes all randomized subjects (47).

Period 1

Period 2

Analysis population for the primary outcome, as defined in the registry: This analysis population includes all subjects who used the study lenses and who met all inclusion criteria and did not meet any exclusion criteria.

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 group includes all randomized subjects.

6. Primary Endpoint

The registry lists the primary outcome as Success Rate of Lens Centration After 7 ± 2 Days of Wear, measured over Day 7, each product.

The primary endpoint was the success rate of lens centration after 7 ± 2 days of wear, reported as a percentage of participants. Lens centration refers to the position of the contact lens over the cornea. During slit-lamp examination, the investigator rated centration on a 5-point scale, with 0 representing optimal centration and 4 representing severe decentration. The endpoint counted a participant as a success if the rating was optimal or slight decentration. One eye, designated as the study eye, was analyzed.

This binary endpoint condenses the underlying five-point rating into a success-or-not-success outcome. Such a definition can make the clinical interpretation straightforward: it reports the proportion meeting the chosen criterion rather than the full distribution of ratings. At the same time, collapsing categories removes information about distinctions among ratings outside the success definition. The registry record does not report the distribution across all five scale values, so the posted success rates cannot show how participants were distributed among the remaining ratings.

The endpoint reflects an investigator’s assessment at the specified visit, rather than a participant-reported measure or a longer-term outcome. The registry record does not report additional primary time points or a separate analysis of the full rating scale.

7. Results Posted in the Registry

• 1DAVTE: 86.7% (39/45) versus 100.0% (42/42) on control; risk difference -13.3 percentage points (95% CI -23.3 to -3.4), risk ratio 0.87 (0.77–0.97); unadjusted two-proportion z-test p = 0.014.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary because each participant’s rating was classified as either success or not success according to the stated threshold. A success required an investigator rating of optimal or slight decentration. The reported percentage is therefore a proportion meeting that definition among the participants counted in the denominator for each product. The underlying rating scale has five points, but the posted primary result does not give counts for every point on that scale.

What does the risk difference describe?

The risk difference is the success proportion for 1DAVTE minus the success proportion for Dailies Total 1, as indicated by the listed comparison and control. Its estimate is -0.133. A negative value means the observed success proportion was lower for 1DAVTE in this contrast. The confidence interval, -0.233 to -0.034, describes a range of values compatible with the data under the method used to construct it. The registry record does not identify that method. The risk difference is an absolute measure, so it is expressed on the proportion scale rather than as a relative comparison.

What does the risk ratio describe?

The risk ratio compares the success proportion for 1DAVTE with the success proportion for Dailies Total 1. The estimate is 0.867, and its reported 95% confidence interval is 0.773 to 0.972. A ratio of 1 would correspond to equal proportions; values below 1 indicate a lower observed proportion for the numerator in this contrast. This is a general explanation of the measure, not a claim about a particular analysis model. A ratio conveys relative scale, whereas the risk difference conveys absolute scale. Looking at both can help distinguish the size and direction of the contrast without treating either as a complete account of the study.

How should the p-value be understood?

The unadjusted p-value is 0.014. In general, a p-value measures how unusual data at least as discrepant as the observed data would be under a specified null hypothesis and statistical model. It does not state the probability that the null is true, and it does not quantify the probability that a particular participant will have a successful outcome. It also does not measure the clinical importance of a difference. Since the test and model are not reported in the registry record, the p-value cannot be independently connected to specific assumptions from the registry entry alone.

The term unadjusted indicates that this value is not identified as adjusted for multiple comparisons. There is one posted outcome measure and no posted analyses, but the registry record does not report a complete statistical analysis plan or state whether other analyses were performed. As a result, the p-value should not be treated as evidence that multiplicity was formally considered or ruled out.

Why does the crossover design matter?

In general, crossover studies can improve efficiency when each participant serves as their own comparison, because measurements from the same participant may share personal characteristics. That benefit depends on analyzing the within-participant structure appropriately. Measurements from one participant are not ordinarily independent in the same way as measurements from different participants. The sequence in which products are used and the period in which an outcome is assessed can also matter. A prior product could potentially influence a later measurement, a general design concern known as carryover.

The registry record identifies randomized product sequences but does not report whether the analysis used paired data, included a period or sequence term, assessed carryover, or handled the order of treatment. The comparison estimates and p-value should therefore be read as posted, without assuming a particular crossover model. The posted summary does not include the participant-level pairing needed to reconstruct such an analysis.

What can planning calculations show?

Planning sample-size illustrations based on an observed effect are not the trial’s original design justification and are not observed power. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. The registry record does not report the trial’s own sample-size justification. No planning sample-size results are described in the registry record, so no required enrollment count can be stated from the record. In general, such calculations are conditional on their assumptions and intended effect size, and should not be mistaken for evidence that a completed study had a particular probability of detecting an effect.

For binary data, the amount of information depends on the outcome proportions and the numbers of participants contributing to each outcome. A proportion near an endpoint of its possible range can yield limited information about variation, even when the observed proportion is striking. Here, the Dailies Total 1 success rate is 100.0%, so there are no observed failures in that denominator. The registry record does not describe whether the analysis used a method designed to address boundary proportions or how uncertainty was estimated.

10. Confidence Intervals and Precision

The 95% confidence interval for the risk difference runs from -0.233 to -0.034. It describes the uncertainty around the estimated contrast on the absolute proportion scale. Its endpoints are both negative, consistent with a lower observed success proportion for 1DAVTE under the stated contrast direction. The width of the interval also matters: the estimate is not known with perfect precision, and values across the interval represent different possible magnitudes of the contrast under the interval’s statistical assumptions.

The 95% confidence interval for the risk ratio is 0.773 to 0.972. This interval expresses uncertainty on a relative scale. A confidence interval is not a guarantee that the true value lies inside its endpoints, nor does it assign probabilities to individual values after the data have been observed. In general, it describes the performance of a procedure that would cover the target parameter at its stated rate over repeated use, if the underlying model and assumptions were appropriate.

The registry record does not state how either interval was calculated. This is particularly relevant for a crossover design and for a success proportion of 100.0% in one group: the method used to account for paired observations and a boundary proportion can affect the interval. No confidence intervals for the separate product-specific success rates are reported in the registry record. The posted intervals therefore support interpretation of the reported contrast, but they do not answer every question about precision, individual ratings, or within-participant outcomes.

The denominators are 42 and 45 for the product-specific outcome rates. These figures indicate how many participants contributed to the respective reported proportions; they are not the same as the randomized enrollment. Why the outcome denominators differ is not reported in the registry record. That uncertainty about the analysis set is relevant when assessing how representative the estimates may be of all enrolled participants.

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no posted analyses beyond the primary comparison. It reports an unadjusted p-value of 0.014. The record does not report a multiplicity adjustment, a prespecified hierarchy for outcomes, or a statistical analysis plan describing how multiple tests would be handled. The absence of reported secondary outcomes does not establish that no additional analyses were considered; it means their status is not reported in the registry record. The p-value should consequently be understood as an unadjusted value, not as evidence of a documented multiplicity strategy.

The primary analysis population is described as participants who used the study lenses, met all inclusion criteria, and did not meet any exclusion criteria. The registry record does not name this population as intention-to-treat, per-protocol, or another standard analysis set. It also does not report exclusions from analysis, missing outcome counts, reasons for missingness, or how missing measurements were handled. The enrollment is 53, while the product-specific outcome denominators are 42 and 45. The record does not explain the difference, so it is not possible to determine from the registry entry whether it arose from missing observations, eligibility decisions, or another reason.

In a crossover trial, missingness can affect the amount of paired information available. A participant may have an outcome recorded for one product but not the other, or may contribute data for both; the registry record does not describe these patterns. It also does not report whether an imputation method was used or whether sensitivity analyses assessed the effect of missing data. These details matter because analysis of only complete pairs can represent a different participant set from analysis using all available observations.

The record’s lack of reported details is not evidence that a method was or was not used. It limits what can be concluded about the analysis population, missing-data handling, and multiplicity from the posted registry information.

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 safety figures list 47 participants at risk for serious adverse events in each product group. The number affected by a serious adverse event is 0 for Dailies Total 1 and 0 for 1DAVTE. The figures for other adverse events also list 47 participants at risk in each group and 0 affected in each group. No serious adverse-event terms are listed.

These are event counts for the safety groups described in the registry record, not the primary outcome denominators. The record does not explain how the safety groups relate to the different primary outcome denominators of 42 and 45. Zero recorded events means none were reported in these figures; it does not establish that the risk of an event is absent, particularly when the number observed is limited. The registry record does not report additional detail about event definitions, collection procedures, follow-up completeness, or the timing of safety assessments.

Death counts are not reported in the registry record. A missing death count should not be read as a count of zero. The safety information is therefore limited to the posted adverse-event counts and should not be used to infer that no events of any kind occurred beyond the categories and reporting described.

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

The posted result shows high success proportions for both products under the trial’s definition of centration success: 100.0% for Dailies Total 1 and 86.7% for 1DAVTE. The reported comparison places 1DAVTE below Dailies Total 1 on both the risk-difference and risk-ratio scales. The risk-difference estimate is -0.133, with a 95% confidence interval from -0.233 to -0.034, and the unadjusted p-value is 0.014. These statistics describe the observed primary outcome and its reported uncertainty.

The result does not establish why the success rates differed. It does not describe the full distribution of ratings on the five-point scale, because only the threshold-based success outcome is posted. It also does not establish that the same contrast would occur in another population, with another assessment procedure, or over a different wearing period. The outcome concerns investigator-rated centration after 7 ± 2 days of wear; it is not a direct summary of all lens characteristics or longer-term experience.

The study was a randomized crossover trial, but the registry record does not report enough analysis detail to determine how within-participant pairing, sequence, period, or potential carryover were handled. The outcome denominators differ, and the reason is not reported. Those uncertainties limit interpretation of the comparison beyond the posted summary estimates.

The p-value is not a measure of clinical importance, and a confidence interval is not a statement that every value inside it is equally plausible or that a result will recur. Nor do the results establish a treatment recommendation. They describe the posted comparison under the trial’s endpoint definition and analysis reporting. Other outcomes, secondary analyses, and the trial’s own sample-size justification are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial illustrates how a binary endpoint can make an investigator-rated measure easy to summarize while leaving important detail out. The five-point centration scale was reduced to a success definition that combined optimal and slight decentration. The resulting percentages answer a clear threshold question, but they do not show how ratings were distributed across the full scale. A reader therefore needs to keep the operational definition in view when interpreting the reported success rates.

It also illustrates why effect measures should be read on their own scales. The risk difference of -0.133 describes an absolute contrast, while the risk ratio of 0.867 describes a relative contrast. Their confidence intervals convey uncertainty about those respective summaries. The unadjusted p-value offers a different kind of information and should not replace consideration of effect size, interval precision, or study design.

The crossover design raises an important statistical question: how observations from participants who used both products were handled. Such designs can use within-participant comparisons, but that requires analysis that recognizes dependence between measurements and considers sequence or period features where appropriate. Since the registry record does not report the analysis method, the posted estimates cannot be fully evaluated as a crossover analysis from the registry entries alone.

Finally, the difference between enrollment and the outcome denominators emphasizes the value of clear reporting about analysis populations and missing data. The registry record states the eligibility basis for the analysis population but does not explain the denominators or missingness. This makes the record useful for understanding the endpoint and posted estimates, while leaving questions about precision and analysis implementation 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The primary limitation in interpreting this specific record is incomplete statistical reporting. The registry record does not identify the test or model used for the primary comparison, explain how the crossover structure was handled, or report whether period, sequence, or carryover were considered. It therefore does not permit a detailed assessment of whether the reported uncertainty and p-value account for within-participant dependence.

The outcome denominators, 42 for Dailies Total 1 and 45 for 1DAVTE, differ from the enrollment of 53. The reason for this difference is not reported in the registry record. There is no posted participant flow, missing-data description, or account of how the analysis population was derived beyond the general eligibility description. Consequently, the relation between randomized participants, those who used each product, and those contributing to each endpoint rate is not fully specified.

The primary outcome reports only whether participants met the success threshold. It does not provide the counts for each rating on the five-point scale, nor does it report separate rates for optimal and slight decentration. The record gives no secondary outcome measures or analyses. As a result, the posted endpoint provides a narrow view of the measured outcome.

Masking is listed as none, and the outcome was investigator-rated. The registry record does not describe any steps to reduce assessment bias. It also does not report allocation concealment, a washout period, a sample-size justification, or a complete statistical analysis plan. The study is identified as a pilot evaluation, but the registry record does not specify a formal objective beyond comparing lens centration. These omissions constrain interpretation; they do not establish that particular procedures were or were not conducted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: DAILIES TOTAL1® Lens Centration in a Japanese Population — NCT02252133.
• Registry record last updated 2016-01-29; status last verified 2015-11.
• Results first posted 2015-12-28.
• 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

NCT02252133, titled DAILIES TOTAL1® Lens Centration in a Japanese Population, was a completed randomized, open-label crossover study sponsored by Alcon Research. The registry lists an enrollment of 53 and a study period from 2014-10 to primary completion in 2014-11. Participants used delefilcon A and narafilcon A contact lenses in randomized order, wearing each product bilaterally for 7 days on a daily-wear, daily-disposable basis.

The primary outcome was the percentage of participants whose investigator-rated lens centration was optimal or slight decentration after 7 ± 2 days. The posted success rates were 100.0% for Dailies Total 1 and 86.7% for 1DAVTE. The risk difference for 1DAVTE relative to Dailies Total 1 was -0.133, with a 95% confidence interval from -0.233 to -0.034; the unadjusted p-value was 0.014. The registry record does not report the statistical model, the explanation for outcome denominators, or further analyses.