A Safety and Effectiveness Study of BL-ABT12 Multi-Purpose Solution for Use by Participants With Soft Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Safety and Effectiveness Study of BL-ABT12 Multi-Purpose Solution for Use by Participants With Soft Contact Lenses (NCT03897751), a randomized na study. The primary outcome is Overall Comfort.

2. Clinical Question

This is a comparison of reported comfort scores in the endpoint population, rather than a comparison of every randomized participant. The registry record reports group means, standard deviations, a mean difference, a confidence interval, and an unadjusted p-value. Those summaries describe the observed scores and the uncertainty around the group comparison; they do not by themselves establish that either solution produces a clinically important difference. The registry record does not report a threshold defining a meaningful comfort difference, so statistical interpretation should remain focused on the estimated score contrast and its precision.

3. Trial Design

The registry record describes a randomized, double-masked, parallel-group study of ABT12 Multi-Purpose Solution and COMPLETE Multi-Purpose Solution. The stated purpose was to evaluate the safety and effectiveness of ABT12 compared with COMPLETE when used by habitual contact lens wearers. The study is marked completed. Its recorded enrollment is 252, and the recorded study dates are 2019-03-08 for start and 2019-08-01 for primary completion.

Participants in the ABT12 group were to use that solution daily to clean their contact lenses for 3 months. Participants in the COMPLETE group were to use COMPLETE daily for the same stated period. Both group descriptions allow Sensitive Eyes Rewetting Drops as needed during the study. The registry record identifies these products as device interventions. The arm descriptions do not specify additional procedures or adherence rules, so those details are not reported in the registry record.

The primary endpoint is Month 3 overall comfort. The primary population is described as randomized participants who attended the 3-month visit and did not have major protocol deviations. The posted endpoint summaries report 117 for ABT12 and 113 for COMPLETE. These endpoint group counts should not be confused with the recorded enrollment: the registry record does not explain the disposition of participants between enrollment and the primary endpoint population.

Although randomization and double masking are recorded, the method of sequence generation, allocation concealment, and the practical masking procedures are not reported in the registry record. The record also does not report the planned allocation ratio or the trial's original sample-size assumptions. The simple planning illustrations associated with the posted effect are separate from the study's original design information.

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

Analysis population for the primary outcome, as defined in the registry: Randomized participants who attended the 3-month visit and did not have major protocol deviations

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 Overall Comfort, measured over Month 3.

Overall comfort is a continuous, patient-reported type of outcome summarized as a mean score. The scale runs from 0 to 100, and the description states that 100 denotes the most favorable response. The assessment is specified for each eye, with the primary time point at Month 3. The endpoint therefore summarizes comfort at the end of the stated 3-month use period, rather than change from a baseline value. A baseline comfort measure is not reported in the registry record.

A continuous score can retain gradations in reported experience rather than reducing responses to a simple yes-or-no category. Comparing group means provides a concise estimate of the average score contrast, while the standard deviations describe variability among observations within each group. These are general statistical properties of continuous outcomes; they do not show whether the scale is equally meaningful across all participants or whether a particular score difference matters to users.

The registry record does not report how responses from each eye were combined, whether the two eyes were analyzed separately, or how any within-participant correlation was handled. It also does not report a clinically important difference threshold. These details matter when interpreting what the group mean represents and whether a numerical contrast would be noticeable or important in practice. The endpoint is best read as the posted Month 3 comfort score comparison for the stated endpoint population, with those measurement and interpretation details unresolved.

7. Results Posted in the Registry

• COMPLETE Multi-Purpose Solution: mean 87.50 versus 88.90 on control; difference -1.40 (95% CI -4.47 to 1.67), standardized effect d = -0.12; z-test p = 0.372.

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean difference represent?

A mean is the arithmetic center of a set of continuous measurements. Here, the posted group means are 88.9 for ABT12 and 87.5 for COMPLETE. The comparison is expressed as COMPLETE minus ABT12, giving -1.4. With that direction, a negative value means the observed COMPLETE mean is lower, while a positive value would mean it is higher. The sign depends on the stated order of subtraction; it does not by itself rank the products on an overall clinical basis.

The means are summaries, not descriptions of every score. The reported standard deviations are 11.49 for ABT12 and 12.24 for COMPLETE. A standard deviation describes the spread of observations around a mean. Larger spread means scores are more dispersed, while a smaller spread means they are more concentrated. Neither the means nor standard deviations alone reveal the shape of the score distributions or whether unusual observations influenced the summaries.

What does the p-value tell the reader?

The unadjusted p-value is 0.372. In general, a p-value measures how compatible the observed data are with a specified null model, under the assumptions used for the analysis. It is not the probability that the null model is correct, and it does not measure the probability that the result will reproduce. A relatively large p-value does not prove that there is no difference. It means the posted analysis does not provide strong statistical evidence against a zero mean difference under its model.

The registry record labels this p-value unadjusted. It does not report adjustment for multiple endpoints or comparisons. The value should therefore be read as the posted unadjusted result, not as a multiplicity-adjusted test. The record does not report details of the test procedure, its degrees of freedom, or model diagnostics, so those features cannot be evaluated from the registry entry.

How should the standardized difference be read?

The posted standardized difference is -0.118. A standardized difference expresses the mean contrast in units of a pooled standard deviation, which can help describe the scale of a contrast relative to observed variability. It is a different representation from the score-point difference, not a separate clinical endpoint. The standardized value does not identify a meaningful comfort threshold, and the registry record does not provide such a threshold. Interpretation should therefore retain the original score scale and its confidence interval rather than relying on a standardized label alone.

What does over-dispersion mean in general?

Over-dispersion is a general concern when observed variability is greater than a statistical model assumes. If a model understates variability, standard errors can be too small and intervals can be too narrow, making evidence appear more precise than it is. This concept is especially relevant to some count outcomes. The primary endpoint is a continuous comfort score, and the registry record does not report an over-dispersion assessment or describe a model that addresses it. It would be inappropriate to assume that over-dispersion was present or that a correction was used.

What does the confidence interval add?

The posted 95% confidence interval for the mean difference is -4.47 to 1.67. In general, a confidence interval gives a range of values compatible with the observed data and the procedure's assumptions. It communicates uncertainty more directly than a p-value alone. The interval includes zero, so it includes no mean difference as one plausible value under the analysis. It also includes negative and positive values, representing possibilities in either direction. The interval is not a guarantee that the true value lies within its endpoints, nor does it assign a probability to any one value.

What is the role of the planning illustrations?

The posted planning illustrations use fractions of the observed effect and list participants per arm for 80% and 90% power. The assumptions state a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. These are planning calculations based on the observed effect, not the trial's original design assumptions. They do not describe the probability that this completed trial detected an effect, and they should not be interpreted as observed power. The registry record does not report the original sample-size justification or whether the original design used these assumptions.

Any calculation from summary statistics also depends on the summaries and methods being appropriate for the intended comparison. The posted comparison is unadjusted, and the record does not give enough detail to assess the analysis model, handling of eye-level measurements, missing data, or protocol deviations beyond the endpoint population definition. These limits do not invalidate the posted numbers; they define how far their interpretation can responsibly extend.

10. Confidence Intervals and Precision

The 95% confidence interval for the COMPLETE-minus-ABT12 mean difference runs from -4.47 to 1.67 points. Its span across zero means the posted data are compatible with a lower mean in COMPLETE, no mean difference, or a higher mean in COMPLETE, within the range represented by the interval and under the analysis assumptions. The point estimate, -1.4, is only one value within that broader uncertainty.

Confidence intervals are useful because they show both direction and precision. A narrow interval would indicate that the estimate is relatively precise under the model; a wide interval would indicate more uncertainty about the size and direction of the contrast. Whether this interval is sufficiently precise for a practical decision depends on what score difference would matter. That threshold is not reported in the registry record, so the interval cannot be classified as excluding or including a clinically important difference.

The reported group standard deviations are 11.49 and 12.24. They provide context for the variability in the observed scores, but they do not account for all possible uncertainty in measurement or analysis. The registry record does not describe how the per-eye assessments were represented in the group summaries or whether correlations between eyes were modeled. It also does not report missing-data procedures, an adjusted analysis, or sensitivity analyses. Those omissions limit assessment of whether the displayed interval captures all relevant uncertainty.

The unadjusted p-value of 0.372 is consistent with the interval including zero, but the interval is more informative about the range of plausible score contrasts. Neither statistic establishes equality. The appropriate conclusion is that the estimate is uncertain in direction and magnitude, with the registry record offering no stated clinical threshold against which to judge its practical importance.

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 planning figures are participants per arm, not total events. They are illustrations calculated from the observed effect rather than a report of the trial's original design. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. The trial's own original sample-size assumptions are not reported in the registry record.

For planning at 100% of the observed effect, the figures are 1,128 participants per arm for 80% power and 1,510 participants per arm for 90% power. For planning at 75% of the observed effect, they are 2,005 participants per arm for 80% power and 2,684 participants per arm for 90% power. For planning at 50% of the observed effect, they are 4,510 participants per arm for 80% power and 6,037 participants per arm for 90% power.

Power is the probability, under a specified assumed effect and statistical model, of rejecting a null hypothesis when that assumed effect is present. The 80% column represents the participant count per group in the illustration for that power target; the 90% column represents the count per group for the higher power target. For the same assumed effect, a higher target generally requires more participants. Likewise, smaller effects need more participants to detect reliably, which is why the stated smaller fractions have larger planning figures. These figures are not observed power and do not establish what the completed trial could or could not detect under its original design.

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 = -1.400; pooled standard deviation σ = 11.864.
2. n = 2 × (1.96 + 0.842)² × 11.864² / -1.400² = 1,127.4, rounded up to 1,128 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 <- -1.40000000000001                      # observed difference in means
sigma <- 11.8643470776502                     # 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(3897751)
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 = 1,128 (80% power), 1,510 (90% power)
 75% of observed effect: n per arm = 2,005 (80% power), 2,684 (90% power)
 50% of observed effect: n per arm = 4,510 (80% power), 6,037 (90% power)
power.t.test: 1128.3 
Simulated power at n = 1,128 per arm: 0.802 (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 record lists four outcome measures, but reports no posted secondary outcome results. It does not describe a hierarchy of endpoints, a multiplicity adjustment, or how the primary endpoint was distinguished from any other planned analyses. The primary comparison has an unadjusted p-value of 0.372. Without the planned testing strategy, it is not possible to determine whether the posted p-value was intended as a single confirmatory test or formed part of a broader set of comparisons.

The primary endpoint population includes randomized participants who attended the 3-month visit and did not have major protocol deviations. This is a defined subset of randomized participants, rather than an explicitly stated intention-to-treat population. The registry record does not report the number or characteristics of participants who did not attend that visit, had major deviations, or were otherwise excluded from the endpoint population. It also does not give reasons for missing endpoint data.

Missing-data handling is not reported in the registry record. There is no description of imputation, a likelihood-based method, a complete-case sensitivity analysis, or assumptions about why data may be missing. This matters because an analysis limited to available endpoint measurements can be affected if missingness is related to comfort or group assignment. The posted group counts alone do not establish whether missingness could have influenced the comparison.

The record also does not report the detailed statistical analysis plan, covariate adjustment, model specification, or handling of the per-eye measurement structure. The method used to account for correlation between eyes, if relevant to the analysis, is not reported in the registry record. These are uncertainties about analysis and reporting, not evidence that a particular method was or was not used. They limit independent assessment of multiplicity, population choice, and robustness.

14. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 1% reporting threshold.

The adverse-event figures report zero serious adverse events in the ABT12 group among 127 participants at risk and zero in the COMPLETE group among 125 participants at risk. The record also reports zero other adverse events in each group, with the same respective at-risk counts, and zero deaths in both groups. No serious adverse-event terms are listed.

These figures describe the event counts recorded in the registry for the stated groups. A zero count means that no events of the listed category were reported in that group in this record; it does not prove that the risk is absent. Event counts can be informative about what was observed, but their interpretation also depends on follow-up, event collection, definitions, and completeness of reporting. Those details are not reported in the registry record.

The safety figures should not be treated as a comprehensive comparison of all possible harms. The record does not provide event timing, severity breakdowns beyond the serious and other categories, exposure-adjusted rates, or a detailed adverse-event analysis. Nor do the counts determine the relative safety of the solutions. They are limited registry summaries and should be read alongside the stated follow-up and reporting limitations.

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

The posted result is an estimate of the difference in Month 3 overall comfort scores for the defined endpoint population. The ABT12 group mean was 88.9, and the COMPLETE group mean was 87.5. With the comparison defined as COMPLETE minus ABT12, the estimated difference was -1.4 points. The 95% confidence interval, -4.47 to 1.67, includes zero and extends in both directions. The unadjusted p-value was 0.372.

These results do not demonstrate that the solutions produce exactly the same comfort scores. Failure to find strong statistical evidence of a difference is not proof of equality or equivalence. Equivalence would require a prespecified margin and an analysis designed to assess whether the interval lies within that margin; neither is reported in the registry record. The results also do not establish that a difference exists, because the interval includes zero and the posted p-value does not provide strong evidence against a zero difference.

Statistical and practical meaning are not interchangeable. A score difference can be statistically estimated without being important to participants, while a difference that matters may be difficult to estimate precisely. The registry record does not identify a clinically meaningful threshold for the comfort scale, so the observed point estimate and interval cannot be translated into a firm judgment about practical importance.

The result applies to the stated endpoint population: randomized participants who attended the 3-month visit and did not have major protocol deviations. It should not automatically be generalized to all randomized participants, other contact lens wearers, other products, or use beyond the period described. The posted endpoint is a Month 3 score, not a longer-term outcome or a change-from-baseline analysis. The registry record does not report enough detail to resolve the effects of missing data, eye-level measurement, or analysis choices.

The adverse-event record reports zero serious adverse events, zero other adverse events, and zero deaths in each group for the stated at-risk counts. Those observations are limited to the categories and reporting in the registry. Neither the comfort comparison nor these safety counts amount to medical advice or a general conclusion about product performance.

16. Why This Trial Matters Statistically

This trial illustrates why a group mean difference should be read together with its confidence interval. The point estimate of -1.4 gives a compact summary of the observed contrast, but the interval from -4.47 to 1.67 makes clear that the estimate is uncertain in both direction and size. Reporting the point estimate alone could overstate how firmly the comparison is known; reporting only the p-value would conceal the range of score contrasts compatible with the data.

The outcome also raises a measurement issue common in clinical research: the meaning of a score depends on how it was collected and summarized. Overall comfort was assessed for each eye, yet the registry record does not report how eye-level measurements were combined or modeled. If measurements within a participant are related, treating them as independent can misrepresent uncertainty. This is a general consideration, not a claim about the analysis used in this trial.

Population definitions affect interpretation as well. The endpoint population excludes randomized participants who did not attend the 3-month visit or had major protocol deviations. Without a missing-data account or a broader analysis population, readers cannot determine how that restriction may affect the estimated comparison. The distinction between enrollment and endpoint counts is therefore statistically relevant, rather than merely administrative.

Finally, planning illustrations based on the observed effect are useful for understanding how assumed effect size and power targets relate to required participants per arm. They are not a substitute for the trial's original sample-size justification, which is not reported in the registry record, and they do not provide observed power. Taken together, these features show why estimates, uncertainty, population, measurement, and planning assumptions all matter when interpreting a clinical trial result.

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 registry record does not report the randomization sequence method, allocation concealment, masking procedures, adherence, or the extent to which participants used the assigned solutions as described. The study is identified as randomized and double-masked, but those labels alone do not provide enough detail to evaluate implementation. The original sample-size justification and assumptions are also not reported.

The primary result is limited to Month 3 and to randomized participants who attended the 3-month visit and did not have major protocol deviations. The record does not describe excluded participants, reasons for missing assessments, or missing-data methods. Consequently, the influence of incomplete follow-up on the endpoint comparison cannot be assessed. No baseline comfort values or change-from-baseline result are reported.

Comfort was assessed for each eye, but the registry record does not explain how eye-level responses were represented in the reported means or how correlation between eyes was addressed. A clinical threshold for a meaningful difference is also not reported. This limits interpretation of both the score contrast and its practical importance.

The record lists four outcome measures but reports no secondary outcome results. It does not describe the analysis plan, multiplicity strategy, model specification, or sensitivity analyses. The posted p-value is unadjusted. Safety reporting is limited to the listed event categories and counts, without event timing or detailed definitions. These reporting gaps constrain independent evaluation; they do not establish that unreported procedures or analyses were absent.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: A Safety and Effectiveness Study of BL-ABT12 Multi-Purpose Solution for Use by Participants With Soft Contact Lenses — NCT03897751.
• Registry record last updated 2023-03-03; status last verified 2023-03.
• Results first posted 2022-11-30.
• 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

NCT03897751 is a completed randomized, double-masked, parallel-group study of ABT12 Multi-Purpose Solution compared with COMPLETE Multi-Purpose Solution in habitual contact lens wearers. The registry record lists enrollment of 252 and describes daily lens cleaning for 3 months, with Sensitive Eyes Rewetting Drops available as needed.

The primary endpoint was Month 3 overall comfort on a 0-to-100 scale, with higher scores described as more favorable. In the defined endpoint population, the posted means were 88.9 for ABT12 and 87.5 for COMPLETE. The COMPLETE-minus-ABT12 mean difference was -1.4, with a 95% confidence interval from -4.47 to 1.67 and an unadjusted p-value of 0.372.

The registry record also reports zero serious adverse events, zero other adverse events, and zero deaths in each group. Important details about missing data, the endpoint analysis, eye-level measurement, multiplicity, and the original sample-size justification are not reported in the registry record.