Clinical Evaluation of Investigational Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of Investigational Contact Lenses (NCT02801396), a randomized na study. The primary outcome is CLUE Handling.

2. Clinical Question

3. Trial Design

This was a randomized, unmasked crossover study of investigational contact lenses, marked completed in the registry record. The listed phase is NA. The study was described as a single-visit, non-dispensing evaluation: subjects wore three different lenses bilaterally during that visit and completed a questionnaire for each study lens. Each lens was worn for approximately 30-60 minutes.

The six sequence descriptions list different orders of Test 1, Test 2, and Control. A 5-minute wash-out period separated lenses. Randomizing order can help distribute order effects across treatment sequences, while a crossover design allows outcomes after different lenses to be collected from the same participants. Those are general design considerations; the registry record does not describe how order effects were modeled or whether the posted comparison analysis accounted for within-person correlation.

Enrollment was 116. The posted primary outcome summaries report 99 for each lens. The outcome population is defined as subjects who completed all study visits without a major protocol deviation. The record does not explain why the number in the outcome summaries differs from enrollment, nor does it report additional details about exclusions or missing questionnaire responses.

The study began on 2016-04-24 and primary completion was 2016-05-22. The sponsor is Johnson & Johnson Vision Care, Inc. The registry record does not report the trial’s original sample-size justification, planned statistical model, or detailed analysis plan. These omissions limit what can be concluded about how the study’s design and analysis were chosen.

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 116 subjects were enrolled into the study. Of the enrolled subjects 15 were not dispensed a study lens. A total of 101 subjects were dispensed a study lens. Of the dispensed subjects 1 was discontinued and 100 subjects completed the study.

Period 1

Reasons for not completing this period:

Period 2

Period 3

Analysis population for the primary outcome, as defined in the registry: Subjects that 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: All subjects that were dispensed at least one study lens.

6. Primary Endpoint

The registry lists the primary outcome as CLUE Handling, measured over 30 Minutes Post Insertion.

The primary endpoint, CLUE Handling, is a continuous questionnaire score reported in units on a scale. It was assessed at 30 Minutes Post Insertion. CLUE stands for Contact Lens User Experience and is described in the registry as a validated patient-reported outcomes questionnaire for experience attributes of soft, disposable contact lenses, including comfort, vision, handling, and packaging. The reported primary outcome concerns the handling attribute.

The record says CLUE scores follow a normal distribution with a population average score of 60 and SD 20; higher scores indicate a more favorable or positive response. It also states that 97% of scores fall within 0 and 120 (mean +/- 3XSD). These are scale-description details, not trial results. The trial results themselves give a mean and standard deviation for each lens.

A patient-reported endpoint captures the participant’s own assessment rather than relying only on an observer’s measurement. This makes it relevant to a study evaluating users’ experience of contact lenses. At the same time, the numerical difference needs context: the registry record does not report a clinically important difference threshold for CLUE Handling. The scores therefore describe reported handling experience on this measure, but alone do not establish how noticeable or important a difference would be in everyday use.

7. Results Posted in the Registry

• Test1: mean 55.73 versus 64.39 on control; difference -8.66 (95% CI -14.23 to -3.09), standardized effect d = -0.43; z-test p = 0.002.
• Test 2: mean 57.58 versus 64.39 on control; difference -6.81 (95% CI -12.37 to -1.25), standardized effect d = -0.34; z-test p = 0.016.

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean difference express?

A mean is the arithmetic average of observations on a continuous scale. The registry reports a mean CLUE Handling score for each lens and a mean difference for each test lens relative to Control. A negative mean difference indicates that the test-lens mean is lower than the control mean in the reported comparison. Since higher CLUE scores are described as more favorable, the direction of these estimates corresponds to lower average handling scores for the test lenses in these posted results.

The standard deviation describes how dispersed individual scores are around their group mean. It is not a measure of uncertainty in the mean itself. The posted standard deviations are close to 20 for all three lens summaries, while the uncertainty in a mean or mean difference is represented more directly by its standard error and confidence interval. General statistical interpretation should keep these quantities distinct: the SD describes participant-level spread, whereas a confidence interval describes uncertainty about an estimated quantity under the analysis assumptions.

How should the confidence intervals be read?

A confidence interval gives a range of values compatible with the estimate under the statistical model and its assumptions. The Test1 comparison has an estimate of -8.66 and interval -14.23 to -3.092. The Test 2 comparison has an estimate of -6.81 and interval -12.37 to -1.248. Each interval expresses uncertainty around its corresponding estimated mean difference; it does not show the range of individual participants’ scores.

Both intervals are entirely negative. In conventional testing against a zero mean difference, that feature aligns with the reported unadjusted p-values of 0.002 and 0.016. This is a general interpretation of intervals and tests, not a statement that the study used any particular model beyond what the registry reports. The record does not give a detailed statistical analysis plan, so the exact construction of the intervals and the assumptions used for the comparisons are not reported in the registry record.

Why does the crossover design matter?

In a crossover study, a participant receives or experiences multiple study conditions in sequence. Consequently, measurements from one person can be related to each other. A statistical analysis may need to account for that relationship; treating all lens observations as independent can misrepresent uncertainty when within-person correlation is present. This is a general methodological point. The randomized lens order and 5-minute wash-out period are described, but the registry record does not say how sequence, period, carryover, or within-person correlation entered the analysis.

The outcome summaries list 99 for each lens and show separate means and standard deviations. Those summaries do not reveal whether the same subjects contributed to every lens outcome, nor do they give paired differences or their variability. The trial description says subjects were to wear all three lenses, but outcome-specific completion and analysis details are not reported. That distinction matters because a paired analysis depends on the relationship between measurements within each subject, information that cannot be recovered from separate group means and SDs alone.

What do the p-values establish?

A p-value measures how incompatible the observed data are with a specified null model, conditional on the analysis assumptions. The registry reports unadjusted p-values for the two test-versus-control comparisons. A small p-value does not measure the size or clinical importance of a difference, and it does not give the probability that the null hypothesis is true. It also does not address biases arising from missing data, lack of masking, analysis choices, or model misspecification.

Because more than one test-versus-control comparison is reported, multiplicity can be relevant: considering several hypotheses can increase the chance of at least one apparently notable result under a broad null. The registry record does not report a multiplicity strategy. The p-values should therefore be read as the posted unadjusted values rather than as values adjusted for the family of comparisons.

What does variation and over-dispersion mean?

For continuous questionnaire scores, variation is described using the SD. Over-dispersion is more commonly discussed for count outcomes, when variability exceeds what a simple probability model expects. It is not the principal issue identified by the CLUE Handling summaries, which are continuous means and SDs. More generally, a model should reflect the outcome’s scale, the design, and the observed variability. The registry record does not identify a fitted model or report diagnostics, so it is not possible to assess those choices from the posted material.

The primary outcome population is restricted to subjects who completed all visits without a major protocol deviation. This is a stated population definition, not a complete account of missing-data methods. The record does not report imputation, sensitivity analyses, or the treatment of partial questionnaire responses. Accordingly, readers cannot determine whether the posted comparisons would change under alternative approaches to missing outcomes.

10. Confidence Intervals and Precision

The estimated mean difference for Test1 versus Control is -8.66, with a 95% confidence interval from -14.23 to -3.092. For Test 2 versus Control, the estimate is -6.81, with a 95% confidence interval from -12.37 to -1.248. The intervals communicate uncertainty in the estimated mean differences. They are not ranges containing a stated proportion of individual scores, and they do not capture every possible source of uncertainty, such as bias from missing data or an analysis model that does not reflect the crossover structure.

Both confidence intervals lie on the negative side of zero. Their widths show that the estimates are not known exactly, even though the direction in the reported intervals is consistent. The p-values reported alongside them are unadjusted: 0.002 for Test1 and 0.016 for Test 2. A confidence interval and p-value answer related questions under a model, but neither tells whether a difference is important to participants. The registry record does not state a clinically important difference threshold for CLUE Handling.

The primary outcome summaries report SDs of 20.15 for Test1, 20.11 for Test 2, and 19.82 for Control. Those values describe spread in the score distributions, rather than precision of the mean differences. Further assessment of precision is constrained because the record does not describe the comparison model, within-person covariance, or missing-data handling. In a crossover study, these details are especially relevant to uncertainty estimation.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations, not a report of the trial’s original design calculation. The original design assumptions are not reported in the registry record. The figures use a two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation. The target effect is set at the stated fraction of the observed effect. These are participants per arm for 80% power and participants per arm for 90% power; they are not total event counts. The event-count convention for time-to-event outcomes does not apply to this continuous outcome.

The 80% power column describes the planned number of participants per arm under the stated assumptions to have an 80% chance of detecting the target effect if that effect is present and the assumptions hold. The 90% power column uses a higher target chance of detection, which generally requires more participants per arm. For example, the planning rows for 100% of the observed effect list 84 and 112 participants per arm for Test1, and 135 and 181 for Test 2, for 80% and 90% power respectively.

The rows for 75% and 50% of the observed effect represent progressively smaller target differences. Smaller effects are harder to distinguish from random variation, so they require more participants under the same assumptions. These figures are not observed power: they are prospective planning illustrations based on the reported effect estimates, not a measure of the probability that the completed trial detected an effect.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -8.660; pooled standard deviation σ = 19.986.
2. n = 2 × (1.96 + 0.842)² × 19.986² / -8.660² = 83.6, rounded up to 84 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -8.66                      # observed difference in means
sigma <- 19.9861444631024                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2801396)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 84 (80% power), 112 (90% power)
 75% of observed effect: n per arm = 149 (80% power), 199 (90% power)
 50% of observed effect: n per arm = 335 (80% power), 448 (90% power)
power.t.test: 84.6 
Simulated power at n = 84 per arm: 0.797 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry reports a primary outcome and two test-versus-control comparisons. Their p-values are explicitly unadjusted. No multiplicity procedure, such as an adjustment to control error across comparisons, is reported in the registry record. When several hypotheses are tested, the chance of at least one false positive can rise if each is interpreted without accounting for the set of tests. The posted p-values should therefore be understood as unadjusted results; the record does not establish how the sponsor intended to interpret multiple comparisons.

Missing-data details are limited. The primary population is defined as subjects who completed all study visits without a major protocol deviation, and each lens outcome summary reports 99. Enrollment is 116. The record does not explain the difference between enrollment and the outcome summaries, identify reasons for non-inclusion, or describe how incomplete questionnaires were handled. Imputation methods, sensitivity analyses, and comparisons of included and excluded participants are not reported in the registry record.

The crossover design also makes the analysis population and pairing important. The study description says subjects wore three lenses in a randomized order, but the posted summaries do not provide participant-level matching or paired-difference variability. The analysis method for within-person correlation, sequence, period, or possible carryover is not reported. Nor does the record provide a detailed statistical analysis plan or identify an intention-to-treat analysis population.

These are limits on interpretation rather than proof that an unsuitable method was used. The registry record does not report enough detail to assess whether multiplicity, missingness, and crossover dependence were addressed in the original analysis. The comparisons can be described as posted, but their robustness to alternative analysis choices cannot be determined from the registry information.

14. 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 serious adverse events and other adverse events separately for Test1, Test2, and Control. The serious-event at-risk counts are 100 for Test1, 100 for Test2, and 101 for Control. The reported serious-event affected counts are 0 in each group. The other-event at-risk counts are also 100, 100, and 101, respectively, with 0 affected in each group.

These figures describe the posted counts for the registry’s adverse-event categories. They do not establish that no event of any kind occurred: the listed result is specifically zero affected for serious adverse events and zero affected for other adverse events in the reported groups. No serious adverse-event terms are listed. Deaths are not reported in the registry record.

The study was a brief, single-visit evaluation, with lenses worn for approximately 30-60 minutes. Safety counts from this setting should be read within that exposure and follow-up context. The registry record does not provide additional details about the duration of safety follow-up, event ascertainment procedures, or a broader safety analysis.

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

The posted results show lower mean CLUE Handling scores for both test lenses than for Control at 30 Minutes Post Insertion. The estimated mean differences are -8.66 for Test1 versus Control and -6.81 for Test 2 versus Control. Their reported confidence intervals are entirely negative, and their unadjusted p-values are 0.002 and 0.016. These findings describe the observed questionnaire comparisons in the outcome population defined by the registry.

They do not establish that the score differences are clinically important. The record provides no threshold for a meaningful CLUE Handling difference, and statistical evidence against a zero difference is not a measure of practical impact. The results also do not address long-term wear: the study was conducted in one visit, with each lens worn for approximately 30-60 minutes.

The findings are specific to the named test lenses, control lens, endpoint, and study conditions. They should not be generalized automatically to other contact lenses, other user populations, or outcomes beyond handling. Although the questionnaire description includes comfort, vision, handling, and packaging, no secondary outcomes are posted in the record.

The study was unmasked, and the record does not report the statistical model, multiplicity strategy, missing-data approach, or treatment of within-person dependence in the crossover analysis. These gaps make it difficult to evaluate possible sources of bias and the robustness of the comparisons. The safety summaries report zero affected for the listed serious and other adverse-event categories, but the brief exposure and limited follow-up details constrain what those counts can say about safety beyond the study setting.

16. Why This Trial Matters Statistically

This trial is statistically instructive because the design and endpoint bring several interpretive issues together. A randomized crossover study can compare multiple conditions within participants, but the analysis needs to reflect the relationship among repeated measurements. The registry describes randomized lens sequences and a wash-out period, yet does not report how paired observations or sequence effects were handled. Separate means and SDs alone cannot show the within-person pattern.

The primary outcome is a patient-reported continuous score, so the mean difference is a direct way to describe the average contrast on the questionnaire scale. The confidence intervals communicate uncertainty around those contrasts, while the standard deviations describe variability among scores. Keeping those interpretations separate prevents individual variation from being mistaken for uncertainty in the estimated comparison.

The two test-versus-control results also illustrate why unadjusted p-values need context when multiple comparisons are made. The record posts both p-values but does not report a multiplicity plan. In addition, the outcome population is restricted to completers without major protocol deviations, while enrollment and outcome counts differ. The registry does not explain missingness or describe sensitivity analyses. These reporting gaps affect how fully readers can judge the evidence, even when the estimates themselves are clearly stated.

Finally, the study’s brief, single-visit exposure defines the scope of inference. The results address handling scores soon after lens insertion under the study conditions; they do not answer questions about longer use or all dimensions of lens experience. Statistical significance, precision, clinical importance, and generalizability are separate considerations, and the record supports only a limited assessment of each.

17. 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 study was unmasked, so participants and study personnel were not described as blinded to lens assignment. For a patient-reported outcome, knowledge of the lens being worn could potentially influence responses; the registry record does not report procedures intended to assess or mitigate that possibility.

The evaluation was a single-visit, non-dispensing study, with each lens worn for approximately 30-60 minutes. This limits the setting to brief wear and does not provide evidence about experience during longer-term use. The posted primary endpoint was assessed at 30 Minutes Post Insertion, so interpretation should remain tied to that time point.

The outcome summaries report 99 observations per lens, compared with enrollment of 116, but the record does not explain the difference or describe missing-data handling. It also does not report the analysis model for the crossover design, including how within-person correlation, order, period, or carryover were handled. No multiplicity strategy or clinically important difference threshold is reported.

The primary population excludes subjects who did not complete all visits or had a major protocol deviation, according to the stated definition. The record does not provide additional participant characteristics or describe how this population relates to all enrolled subjects. These reporting limits do not establish that the analysis was inappropriate, but they restrict independent assessment of selection, precision, and generalizability.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Clinical Evaluation of Investigational Contact Lenses — NCT02801396.
• Registry record last updated 2017-07-11; status last verified 2017-06.
• Results first posted 2017-06-09.
• 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.

21. Record Summary

NCT02801396 is a completed, randomized, unmasked crossover study titled Clinical Evaluation of Investigational Contact Lenses. The registry lists enrollment of 116 and a single-visit, non-dispensing evaluation of Etafilcon A Design 1 (Test 1), Etafilcon A Design 2 (Test 2), and Etafilcon A (Control). Subjects wore lenses bilaterally in randomized sequences, with approximately 30-60 minutes of wear per lens and a 5-minute wash-out period.

The primary outcome was mean CLUE Handling score at 30 Minutes Post Insertion, among subjects who completed all visits without a major protocol deviation. The posted means were 55.73 for Test1, 57.58 for Test 2, and 64.39 for Control. Comparisons with Control were negative for both test lenses, with unadjusted p-values of 0.002 and 0.016. The registry does not report the original sample-size rationale, detailed statistical analysis plan, multiplicity approach, or missing-data methods.