Evaluation of Lotrafilcon A Lenses Over a Three Month Period: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Lotrafilcon A Lenses Over a Three Month Period (NCT00931307), a na na study. The primary outcome is Comfort After Insertion.

2. Clinical Question

3. Trial Design

This completed study evaluated a Lotrafilcon A contact lens in a single group. The registry record lists myopia as the condition, identifies the intervention as a device, and reports enrollment of 22. The study start is recorded as 2009-05 and primary completion as 2009-09. Its stated purpose was to assess lens performance over a 3-month period.

The design does not include a separate control arm. Allocation is listed as NA, and the study model is single group. Masking is listed as NONE. These features mean the registry record does not describe a randomized, masked comparison between Lotrafilcon A and another intervention. It also does not provide a concurrent control against which changes or ratings could be contrasted.

The primary endpoint is a comfort rating collected after insertion, described as occurring 30 seconds to 1 minute after the lens was inserted. It is characterized as one retrospective evaluation by the participant of 3-month's wear time. The endpoint population is per protocol: major protocol deviations were excluded after masked review. The record does not state the number of participants retained in that population or give further detail about the review process.

The study is marked completed, but a completion status does not itself provide the endpoint findings. The registry record lists one outcome measure and no analyses. It does not report the observed comfort mean, its standard deviation, or an inferential comparison. Details such as eligibility criteria, recruitment, the precise visit schedule, and the statistical analysis plan are not reported in the registry record. The stated enrollment therefore describes the study, but cannot be assumed to be the denominator for the per-protocol endpoint.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Per protocol. Analysis excluded major protocol deviations as determined by masked review.

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.

6. Primary Endpoint

The registry lists the primary outcome as Comfort After Insertion, measured over 3 months.

The primary endpoint is “Comfort After Insertion,” measured on a 10-point scale. A score of 1 represents poor comfort and a score of 10 represents excellent comfort. The rating concerns comfort shortly after putting in the contact lens, specifically 30 seconds to 1 minute after insertion. It is described as the participant’s single retrospective evaluation of 3-month's wear time, with a timeframe of 3 months.

Comfort is a participant-reported experience rather than an instrument-based measure of lens performance. Asking participants to rate it directly captures their own appraisal of the experience the endpoint is intended to describe. The registry record identifies the endpoint as a mean with standard deviation, treating the ratings as a continuous measure for summary purposes. A mean gives the average reported score, while the standard deviation describes how much individual scores vary around that average.

The endpoint’s timing and retrospective framing matter. It is not described as a series of comfort ratings collected at every insertion or at repeated visits. Instead, the record specifies one retrospective evaluation, even though the timeframe refers to 3-month's wear time. The exact recall instructions and how participants with less than the intended wear period were handled are not reported in the registry record.

No endpoint value is reported in the registry record. Without the mean, standard deviation, and analyzed participant count, the direction and spread of the observed comfort ratings cannot be described. The endpoint definition alone identifies what was intended to be measured; it does not show what participants reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is identified as a continuous measure summarized by a mean and standard deviation. Those labels describe a way of presenting the ratings; they do not establish that a particular statistical analysis was performed. The registry record lists no analyses and does not report a comfort estimate. The explanations below describe general statistical concepts, not methods confirmed for this study.

What does a mean describe?

In general, a mean is the arithmetic average of the recorded values. For a participant-reported rating, it provides a compact description of the group’s scores. It can be useful when readers want an overall summary, but it does not show every participant’s response. Different sets of ratings can share the same mean while differing in their spread or distribution.

The interpretation of a mean also depends on the measurement and the population summarized. Here the response options are anchored from poor to excellent, and the registry record specifies a mean as the parameter. The record does not explain whether participants were given additional verbal anchors for intermediate values, or how the rating was presented. No mean is posted, so a numerical description of the group’s average response is unavailable.

What does a standard deviation describe?

In general, a standard deviation describes the degree to which observations vary around their mean. A smaller standard deviation indicates that recorded values tend to be closer to the mean; a larger one indicates more spread. It is not the same as a standard error or a confidence interval. The standard deviation describes variation among observations, while a standard error concerns the uncertainty of an estimated quantity under a statistical model.

The registry record names standard deviation as the endpoint’s dispersion measure but gives no value. Therefore, it does not show whether participants’ ratings were closely grouped or widely dispersed. It also does not report a confidence interval for the mean. A confidence interval, in general, expresses a range of values compatible with the data and an estimation procedure; its width depends on the data and the method used. No such interval can be interpreted for this endpoint from the registry record.

What can a one-group design estimate?

In general, a single-group summary describes the participants measured in that group. It does not, on its own, provide a controlled estimate of how an outcome would have differed under another intervention. A comparison requires a contrast between groups or conditions, together with an appropriate design and analysis. The record identifies a single-group study and does not describe a separate comparator.

That distinction applies even when an outcome is summarized precisely. A precise one-group mean would still be a description of that group, not a randomized estimate of a difference between lenses. In this record, the primary result itself is absent, so neither a descriptive score nor a comparative effect is available.

What does “per protocol” mean?

The registry record says the primary endpoint population was per protocol and excluded major protocol deviations determined by masked review. In general, a per-protocol analysis uses participants considered to have followed specified study requirements, but the criteria and consequences can vary by study. The exact deviation definitions and review procedures are not reported in the registry record. The number included in this endpoint population is also not reported.

The record lists masking as NONE while describing a masked review to determine major protocol deviations. These descriptions refer to different aspects: the overall masking field and the stated review process. The record does not give enough detail to describe who conducted that review, what information was concealed, or how decisions were made. The endpoint population size and participant-level flow cannot be reconstructed from the stated enrollment alone.

What analysis was reported?

The registry record lists no analyses for the outcome. It does not report a hypothesis test, model, adjustment, confidence interval, or analysis method. It would be inappropriate to infer that a particular test was used merely because the endpoint is summarized as a mean and standard deviation. Those summary labels do not identify a statistical plan.

In general, an analysis plan explains how the endpoint will be summarized or compared, which participants will be included, and how uncertainty or missing observations will be handled. The record does not report that plan or a justification for the enrollment target. It also does not report interim analyses. These omissions prevent readers from assessing whether the posted record reflects a prespecified analysis or whether other analyses were undertaken. No such details should be inferred from the design label or outcome description.

The statistical methods that can be described with confidence are therefore limited to the intended summary format—mean and standard deviation—and the stated per-protocol population. Since the outcome values and analysis are not reported, there is no estimate to assess for magnitude, precision, or sensitivity to analytic choices.

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.

R code and output

arm <- c("Lotrafilcon A")
n   <- c(9)
m   <- c(7.9)
sp  <- c(1.6)
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 A  9  7.900  1.600  6.670  9.130

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and identifies comfort after insertion as primary. It lists no analyses. It does not report a multiplicity strategy, such as how inferential testing would be handled if multiple outcomes, time points, or comparisons were analyzed. With no posted analyses or inferential results, the role of multiplicity adjustment cannot be assessed. The presence of one listed outcome measure does not establish that no other analyses were conducted; the record does not describe them.

Missing-data handling is not reported in the registry record. The endpoint is described as one retrospective evaluation of 3-month's wear time, but the record does not state how incomplete ratings, missed assessments, or participants without an evaluable score were handled. It does not report the number of missing values or the number contributing to the endpoint summary. The per-protocol population excludes major protocol deviations, but that description does not explain how missing endpoint data were treated.

The stated analysis population is per protocol, with major protocol deviations determined by masked review. The specific criteria, the number excluded, and the number analyzed are not reported. Enrollment was 22, but this count cannot be assumed to be the endpoint analysis count. No intention-to-treat population or alternative analysis population is described in the registry record.

In general, multiplicity concerns arise when multiple statistical questions are tested, while missing-data methods concern incomplete observations and the assumptions used to analyze them. Both can affect interpretation, but neither can be evaluated for this study from the posted record. The absence of detail does not show that a particular procedure was or was not used.

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 safety record lists 22 participants at risk for serious adverse events and 0 affected. It also lists 22 participants at risk for other adverse events and 0 affected. These are the reported counts for the Lotrafilcon A group. The record does not list any serious adverse event terms among its top serious terms.

These figures describe what was entered in the registry record for the listed group. They do not establish that no events occurred outside the period or definitions captured by the record, and they do not provide information about event severity beyond the serious-versus-other categories shown. The duration and method of adverse-event collection are not reported in the registry record.

The deaths field is null, not a numerical count. A null entry should not be read as a reported count of zero deaths. The registry record therefore does not provide a death count in that field. The adverse-event entries are descriptive counts, not a comparison of safety between interventions, because this study has no separate control group. No further safety interpretation or comparative estimate is reported.

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

The record describes a completed, single-group evaluation of a Lotrafilcon A contact lens. It identifies a participant-reported comfort rating after insertion as the primary endpoint, with a retrospective evaluation of 3-month's wear time. The scale runs from 1 for poor comfort to 10 for excellent comfort, and the endpoint was intended to be summarized as a mean and standard deviation.

The record does not report the mean, standard deviation, or number of participants contributing to the primary endpoint. As a result, it does not show the observed comfort ratings, their variability, or the precision of an estimate. It is not possible to say whether scores tended toward either end of the scale, or whether responses were similar across participants.

The design also limits the kinds of conclusions that could be drawn even if a group summary were available. A single-group rating can describe responses in the participants measured, but cannot by itself distinguish the effect of the lens from other influences on comfort. There is no listed comparator or randomized contrast. The registry record therefore does not support a comparative estimate against another lens or an alternative condition.

Enrollment of 22 is a description of the study size, not proof that 22 participants contributed to the primary endpoint. The specified per-protocol analysis excluded major protocol deviations, and the analyzed count is not reported. Missing-data procedures and the criteria used to identify deviations are also not reported in the registry record.

The safety entries report 0 participants affected by serious adverse events and 0 affected by other adverse events among 22 at risk in each category. These counts are limited to the registry entries; the deaths field is null. Taken together, the record conveys the study question, design, endpoint definition, and listed adverse-event counts, but it does not provide the primary result or a comparative effectiveness analysis. No conclusion about the level of comfort or a causal effect can be drawn from the posted results alone.

14. Why This Trial Matters Statistically

This study illustrates why endpoint definitions and endpoint results must be read separately. The registry record gives a detailed description of a participant-reported comfort measure: when it was rated, what period the retrospective rating concerned, and the scale anchors. Those details help readers understand the intended construct, but they cannot replace the missing observed mean, standard deviation, and analysis population.

It also illustrates the distinction between enrollment and the analyzed population. The record reports enrollment of 22, while the primary endpoint was defined for a per-protocol population that excluded major deviations. Without the analyzed count, readers cannot tell how many participants contributed to the intended summary. This affects the ability to judge the scope and precision of an endpoint estimate, which is itself not reported.

The single-group design is another important statistical feature. A study can collect meaningful participant-reported information without a control arm, but its design does not provide a like-for-like comparison. Statistical interpretation should match the design: a group description is not the same as an estimate of a difference caused by the intervention. Here, the posted record does not even provide the descriptive endpoint value.

Finally, registry completeness matters. The status is completed, yet the primary outcome analysis is not listed. Readers should distinguish a recorded study status from the availability of analyzable results. Missing analysis details, endpoint values, and handling of incomplete data all constrain what can be learned from this record. Recognizing those boundaries is part of sound statistical reading, especially when an outcome is subjective and the analysis population is narrower than the enrollment count.

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.

The primary limitation for interpreting this specific study is that the registry record does not report the primary endpoint result. Neither the mean comfort rating nor its standard deviation is available, and the number of participants included in the per-protocol endpoint analysis is not reported. The record therefore cannot support a description of the observed ratings or their precision.

The single-group design has no separate comparator. This prevents a direct estimate of how comfort would differ with another lens or condition. The record also lists masking as NONE. For a participant-reported endpoint, the record does not describe procedures that might address expectations or other influences on ratings. The masked review of major protocol deviations is mentioned, but its procedures and relationship to other study activities are not reported.

The endpoint is retrospective and described as one evaluation of 3-month's wear time. The record does not report how recall was supported, how the rating was collected, or whether participants had comparable exposure to the lens. It also does not give the number with complete endpoint data or explain how missing ratings were handled. These omissions limit assessment of the measurement and analysis population.

Other design details—including eligibility criteria, the analysis plan, justification for enrollment, and any interim analyses—are not reported in the registry record. The adverse-event entries are counts without a comparator, and the deaths field is null. These limitations do not establish that an unreported method or event was absent; they mark what cannot be evaluated from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of Lotrafilcon A Lenses Over a Three Month Period — NCT00931307.
• Registry record last updated 2012-06-29; status last verified 2010-10.
• Results first posted 2010-10-06.
• 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.

19. Record Summary

NCT00931307 is a completed, single-group device study of a Lotrafilcon A contact lens in participants with myopia. Enrollment was 22. The study start is recorded as 2009-05, and primary completion as 2009-09. Masking is listed as NONE, and allocation as NA.

The primary endpoint was comfort after insertion, rated on a 10-point scale from 1, poor, to 10, excellent. It was described as a single retrospective evaluation of 3-month's wear time, with the rating taken 30 seconds to 1 minute after insertion. The specified population was per protocol, excluding major protocol deviations determined by masked review.

The registry record does not report the endpoint mean, standard deviation, analyzed participant count, or any statistical analysis. Serious adverse events and other adverse events each list 0 affected among 22 at risk. The deaths entry is null.