Study Assessing Patient Satisfaction With LATISSE® for Increasing Eyelash Prominence: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study Assessing Patient Satisfaction With LATISSE® for Increasing Eyelash Prominence (NCT01448525), a randomized phase 4 study. The primary outcome is Percentage of Participants Who Are Satisfied or Very Satisfied With Their Eyelashes Overall.

2. Clinical Question

The registry record identifies patient satisfaction as the study’s purpose. The primary question focuses on a participant-reported assessment of eyelashes overall, rather than an assessment limited to a clinical rating of eyelash appearance. The study also recorded a secondary eyelash assessment outcome, but the primary comparison is the Week 16 satisfaction measure.

The posted primary results include 43 participants in the bimatoprost group and 42 in the vehicle group. The reported satisfaction percentages were 67.4% and 7.1%, respectively. These are descriptive results for the participants included in the outcome analysis. The registry record does not report enough detail to determine how participants without a Week 16 assessment were handled, beyond defining the primary population as randomized participants with at least one post-baseline efficacy assessment.

3. Trial Design

The registry record describes a randomized, triple-masked, parallel-group phase 4 study of bimatoprost ophthalmic solution 0.03% and bimatoprost vehicle solution. Enrollment was 88, and the study status is completed. The listed study dates are 2011-10 for study start and 2012-04 for primary completion. The condition listed is hypotrichosis.

Participants in both groups applied one drop of their assigned solution to the upper eyelid margin of both eyes once daily in the evenings for 16 weeks. The registry record describes the study as triple-masked but does not specify which groups of people were masked. It also does not report the method used to generate the randomization sequence, how treatment allocation was concealed, or whether masking was assessed.

The primary outcome was measured at Week 16 and concerned overall eyelash satisfaction. The reported outcome population included randomized participants who had at least one post-baseline efficacy assessment. The arm-specific outcome counts were 43 for bimatoprost and 42 for vehicle. These outcome counts are distinct from the overall enrollment figure; the registry record does not give a participant-flow account explaining the difference.

The registry record lists one secondary outcome: the percentage of participants with at least a 1-grade increase in the Global Eyelash Assessment score. It lists two outcome measures, but does not report a count of statistical analyses. Details of the trial’s original sample-size justification, planned interim analyses, analysis plan, and any prespecified rules for handling missing outcomes are not reported in the registry record.

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: Intent to treat population included all randomized participants who had at least 1 post-baseline efficacy assessment.

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 Percentage of Participants Who Are Satisfied or Very Satisfied With Their Eyelashes Overall, measured over Week 16.

The primary endpoint is the percentage of participants who were satisfied or very satisfied with their eyelashes overall at Week 16. Participants answered question #3 of the Eyelash Satisfaction Questionnaire, which asks, “Overall, how satisfied are you with your eyelashes?” The questionnaire uses a 5-point scale: -2 is very unsatisfied, -1 is unsatisfied, 0 is neutral, 1 is satisfied, and 2 is very satisfied. The endpoint counts responses of 1 or 2.

This endpoint is useful for addressing a question about participants’ own experience. A participant’s overall satisfaction can reflect the appearance they perceive and their personal evaluation of it. It is not interchangeable with a clinician’s rating or an objective measurement of eyelash characteristics. The registry record lists the Global Eyelash Assessment as a separate secondary outcome, making the distinction between satisfaction and an eyelash assessment relevant to interpretation.

The endpoint is binary for analysis: each participant either meets the definition of satisfied or very satisfied, or does not. The reported percentages therefore describe the proportion meeting that definition in each group, not the average questionnaire score or the degree of satisfaction among only those who were satisfied. The registry record specifies Week 16 as the primary outcome time point. It does not report a primary endpoint result at another time point.

7. Results Posted in the Registry

• Bimatoprost Ophthalmic Solution 0.03%: 67.4% (29/43) versus 7.1% (3/42) on control; risk difference 60.3 percentage points (95% CI 44.3 to 76.3), risk ratio 9.44 (3.11–28.65); unadjusted two-proportion z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Percentage of Participants With at Least a 1-Grade Increase in the Global Eyelash Assessment (GEA) Score

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Bimatoprost Ophthalmic Solution 0.03%: 72.1% (31/43) versus 19.0% (8/42) on control; risk difference 53.0 percentage points (95% CI 35.1 to 71.0), risk ratio 3.78 (1.97–7.25); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Bimatoprost Ophthalmic Solution 0.03% than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The registry record lists one secondary outcome, the percentage of participants with at least a 1-grade increase in the Global Eyelash Assessment score. Its reported direction is consistent with the primary outcome’s broad pattern: the posted results favor a greater proportion meeting the specified outcome in the bimatoprost group than in the vehicle group. The secondary assessment concerns an eyelash rating rather than the participant’s overall satisfaction, so it provides a related but distinct perspective.

Taken together, the primary and secondary outcomes address different aspects of the study question. Satisfaction is directly participant-reported, while the Global Eyelash Assessment outcome is defined by a grade increase. A consistent direction across these measures can add context, but the endpoints are not interchangeable and one does not validate the other automatically. Neither outcome by itself describes every dimension of eyelash appearance or participant experience.

The secondary comparison is unadjusted. Secondary outcomes are generally interpreted with more caution than a prespecified primary outcome because they can be numerous, may be exploratory, and may be affected by selective emphasis or multiple testing. The registry record does not report whether the secondary outcome was formally designated for confirmatory testing, whether a testing order was prespecified, or whether any multiplicity correction was planned or performed.

For that reason, the secondary result is best treated as supportive context rather than as an independent confirmation. Its interpretation depends on the analysis population, missing outcome handling, and the overall analysis plan, details that are not fully reported in the registry record. No additional secondary outcomes are listed in the posted results posted for this study, and the reported-analysis details for the secondary endpoint are not described in the registry record.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Percentage of Participants With at Least a 1-Grade Increase in the Global Eyelash Assessment (GEA) Score

9. Statistical Interpretation

10. Statistical Methods Explained

The main outcome is a binary percentage: participants are classified according to whether their Week 16 answer was satisfied or very satisfied. This turns the five response options into two analysis categories. The percentage in each group is the number meeting the definition divided by the number included in that group’s outcome analysis, expressed as a percentage. The posted counts are 29 of 43 and 3 of 42.

What does the risk difference describe?

The risk difference is the contrast between the two groups’ proportions meeting the endpoint. It is expressed on the probability scale. The posted value is 0.603. A positive value indicates a higher proportion meeting the satisfaction definition in the bimatoprost group than in the vehicle group. It is a difference in proportions, not a ratio of probabilities and not a measure of how much satisfaction changed for an individual participant.

For binary outcomes, other contrasts can also be calculated, such as a risk ratio or an odds ratio. These describe the same group comparison using different scales and can be harder to interpret as direct changes in proportions. The central interpretation is the group-specific percentages and the posted risk difference. No additional contrast is needed to understand the direction of the primary result.

What does the confidence interval add?

General explanation: a confidence interval conveys uncertainty around an estimate by giving a range of values compatible with the data under the statistical method used. It is not a range containing every participant’s outcome, and it is not a guarantee that the true effect lies within the interval. For the primary risk difference, the posted interval lies above no difference. Its width reflects uncertainty in the estimate; the point estimate alone would not communicate that uncertainty.

How should the p-value be read?

The posted unadjusted p-value is <0.001. General explanation: a p-value is calculated under a statistical model that assumes no group difference and describes how unusual data at least as incompatible with that model would be. It does not measure the probability that a treatment effect is real, the probability that the result occurred by chance, or the clinical importance of the result. It also does not replace the effect estimate and confidence interval.

The term unadjusted indicates that the reported p-value is not presented as corrected for testing multiple outcomes or comparisons. The registry record does not report a multiplicity adjustment. When several outcomes are assessed, the chance of finding at least one apparently strong result can be affected by how many tests are performed. This is one reason to consider the primary outcome separately from secondary findings.

Why can variation exceed a simple model’s expectations?

General explanation: a binomial model treats each participant’s outcome as one of two categories and describes the expected variation in the count of participants meeting the endpoint. Over-dispersion means that the observed variability is greater than the model expects. It can make standard errors and confidence intervals too small if it is ignored. The registry record does not report an over-dispersion assessment or an alternative model for the primary binary outcome; no conclusion about such a feature can be drawn from the posted summary alone.

The primary outcome is reported for an intent-to-treat population defined as all randomized participants with at least one post-baseline efficacy assessment. This definition retains randomized participants who meet that post-baseline condition, but it is not identical to a population containing every randomized participant regardless of follow-up. The registry record does not describe the handling of missing Week 16 responses, imputation, or sensitivity analyses. The count of participants contributing to the outcome is therefore important context for the percentages.

The posted comparisons are labelled as recalculated, unadjusted comparisons from summary statistics. The registry record does not report a sponsor analysis for these comparisons, and no discrepancy is identified. The original statistical analysis plan, test-selection rationale, and any adjustments for baseline characteristics are not reported. Accordingly, interpretation should stay with the posted unadjusted group summaries and comparison rather than assume an unreported model or adjustment.

The distinction between statistical and clinical interpretation also matters. Statistical methods assess the compatibility and precision of the group contrast under stated assumptions. They do not establish whether a difference is important to participants, how it compares with a meaningful threshold, or whether it persists beyond the measured time point. The registry record does not report a threshold for a clinically important difference in the satisfaction measure.

11. Confidence Intervals and Precision

The primary outcome estimates are based on 43 participants in the bimatoprost group and 42 in the vehicle group. The observed percentages were 67.4% and 7.1%. The point estimate for the unadjusted risk difference is 0.603. These figures give a concise description of the observed group contrast, while the confidence interval communicates the uncertainty around that contrast.

The posted confidence interval for the primary risk difference lies entirely above no difference. This indicates that the interval’s compatible values are positive under the method used. The interval is not so narrow that the point estimate should be treated as exact: a range of positive effect sizes remains compatible with the data. The registry record does not report a confidence level in the outcome description, so the interval is referred to without assigning an unreported level.

Precision depends in part on how many participants contribute outcomes and how those outcomes are distributed. With a binary endpoint, each participant contributes to one of two categories, and relatively few participants in one category can make estimates less stable. The group counts and confidence interval should therefore be considered together rather than relying on the point estimate or p-value alone.

Confidence intervals describe statistical uncertainty under the analysis method; they do not account for every possible source of uncertainty. They cannot resolve concerns about missing data, the measure’s subjective nature, or whether the registry record fully describes the analysis. The registry record does not provide sensitivity analyses that would show how alternative missing-data assumptions might affect the result.

12. 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 expressed as participants per arm, not total events. The assumptions listed for these illustrations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning scenario uses a stated fraction of the observed effect as the effect to detect. The original trial’s own sample-size assumptions and justification are not reported in the registry record.

For planning at 100% of the observed effect, the illustration gives 9 participants per arm for 80% power and 12 participants per arm for 90% power. For planning at 75% of the observed effect, the figures are 15 participants per arm for 80% power and 20 participants per arm for 90% power. For planning at 50% of the observed effect, they are 29 participants per arm for 80% power and 38 participants per arm for 90% power.

In plain language, the 80% power column describes an assumed design that would have an 80% chance of detecting the specified effect under the listed planning assumptions if that effect were the true one. The 90% power column describes the corresponding planning target with a higher chance of detection. The columns are not statements about what happened in this completed trial. Smaller effects require more participants to detect under the same assumptions, which is why the planning figures increase as the assumed effect becomes a smaller fraction of the observed effect.

These values are planning calculations based on the observed result, not observed power. They should not be read as the trial’s actual enrollment target or as evidence that its original design used these assumptions. The curve and per-arm values are useful for understanding how planning needs change with the assumed effect size, but they do not replace the registry record’s unreported original design rationale.

13. 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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.071; treatment proportion p₁ = 0.674; average p̄ = 0.373.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6839 = 1.3404.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5347 = 0.4500.
4. n = (1.3404 + 0.4500)² / (0.6030)² = 8.8, rounded up to 9 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
p0 <- 0.0714285714285714                          # control proportion
p1 <- 0.674418604651163                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1448525)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 9 (80% power), 12 (90% power)
 75% of observed effect: n per arm = 15 (80% power), 20 (90% power)
 50% of observed effect: n per arm = 29 (80% power), 38 (90% power)
power.prop.test: 8.8 
Simulated power at n = 9 per arm: 0.845 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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.

14. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome and one secondary outcome. It does not report a multiplicity strategy, such as a testing hierarchy or adjustment of significance levels. The posted primary p-value is unadjusted, and the secondary comparison is also unadjusted. When more than one outcome is examined, unadjusted p-values do not account for the possibility of false-positive findings across the set of tests. The magnitude of that concern depends on the full set of analyses, which is not reported in detail.

The registry record lists zero reported analyses, despite posting outcome summaries and comparisons. It does not provide a full statistical analysis plan or enough information to establish whether the reported comparisons were prespecified, whether alternative analyses were conducted, or whether any results were omitted. The absence of a reported multiplicity approach should not be interpreted as evidence that no approach was used; its use is not reported in the registry record.

The primary population is defined as all randomized participants with at least one post-baseline efficacy assessment. The arm-specific primary outcome counts are 43 and 42. The registry record does not give a participant-flow account, explain reasons for missing assessments, or state how participants without a Week 16 response were treated. It also does not report imputation, a missing-data sensitivity analysis, or the assumptions used for any missing outcomes.

These details matter because a complete-case analysis, an imputation approach, or another missing-data method can lead to different estimates when outcomes are unavailable. Without the number and pattern of missing responses and the analysis method, it is not possible to assess how robust the posted result is to missingness. The registry record does not report whether baseline characteristics were adjusted for in the primary analysis or whether analyses were conducted in additional populations.

The trial’s original sample-size justification and interim-analysis plan are not reported in the registry record. Those omissions limit assessment of how the study was planned to control error rates and how the number of participants was chosen. The posted planning illustration is a separate calculation based on the observed effect and should not be mistaken for the trial’s own design plan.

15. 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.

Most frequent non-serious adverse event terms

For serious adverse events, the registry record lists 44 participants at risk in each group and zero participants with a serious adverse event in each group. These are the reported serious-event figures for the treatment groups. The record does not list any serious adverse-event terms.

The registry record also lists other, non-serious adverse events affecting 1 participant in the bimatoprost group and 3 participants in the vehicle group, with 44 at risk in each group. Deaths are not reported in the registry record. These figures should be read as counts for the recorded safety categories, not as a complete characterization of all possible adverse experiences.

Zero recorded serious adverse events in these groups does not establish that no serious events could occur, and the small group counts limit how much can be concluded about uncommon events. The registry record does not provide event descriptions, timing, severity details beyond the listed categories, or a comparative safety analysis. The counts therefore describe what was posted without establishing a broader safety profile.

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

The posted results show that a greater proportion of participants in the bimatoprost group met the Week 16 definition of satisfied or very satisfied than participants in the vehicle group. The unadjusted risk difference is positive, its confidence interval lies above no difference, and the unadjusted p-value is <0.001. These are findings about the registry’s defined outcome and analyzed population.

They do not establish that every participant experienced increased satisfaction, that satisfaction changed by the same amount for each person, or that all aspects of eyelash appearance changed. The endpoint groups responses into satisfied or very satisfied versus all other responses. The registry record does not provide the distribution across all five response categories or individual-level changes from baseline.

The result also does not establish how long any difference might last. The primary outcome is reported at Week 16, and longer-term outcomes are not reported in the registry record. The findings cannot be extended to populations or circumstances not described by the study record. Nor does a statistically clear contrast by itself determine how important the difference is to participants; the registry record does not state a threshold for meaningful change.

Randomization and masking are design features that can support a fair comparison, but the registry record does not describe the specific procedures used. Interpretation is also limited by the outcome population definition and the lack of reported detail about missing observations, multiplicity, and the full statistical plan. The results should therefore be understood as a comparison of the posted group outcomes, with those reporting limitations in view.

The study’s primary result is patient-reported, while its secondary outcome uses the Global Eyelash Assessment. These measures offer different information and should not be treated as substitutes. The record supports describing the posted Week 16 satisfaction contrast and the general direction of the secondary finding, but not broader claims beyond the measured outcomes and follow-up reported.

17. Why This Trial Matters Statistically

This trial illustrates why the outcome definition matters as much as the treatment comparison. The primary endpoint is not simply eyelash prominence; it is the percentage meeting a threshold on a participant-reported satisfaction question. Its interpretation depends on the chosen threshold, the questionnaire response scale, and the time point at which the response was collected.

It also demonstrates how an absolute contrast can make a binary result more interpretable. The group percentages describe the observed proportions, while the risk difference expresses their contrast on the probability scale. The confidence interval adds information about precision that neither the percentages nor the p-value convey alone. Keeping these quantities together helps distinguish the estimated size of a contrast from the uncertainty around it.

The study record also shows the importance of population definitions and transparent analysis reporting. The primary population requires at least one post-baseline efficacy assessment, while the outcome counts are smaller than the overall enrollment figure. Without a participant-flow explanation or missing-data methods, readers cannot fully assess the implications of those counts for the result.

Finally, a primary outcome and a secondary outcome can provide related but nonidentical evidence. A consistent direction may be informative, but unadjusted secondary findings require caution when multiplicity procedures and prespecification are not reported. The registry record leaves important planning and analysis details unreported, underscoring why effect estimates, uncertainty, endpoint meaning, and reporting completeness all matter when interpreting a clinical trial.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The registry record gives limited detail about the methods used to conduct the trial. It identifies randomization, triple masking, and a parallel design, but does not describe the random sequence, allocation concealment, or which parties were masked. These omissions make it difficult to assess the practical implementation of those design features from the record alone.

The primary outcome is based on one satisfaction question and a threshold that combines satisfied and very satisfied responses. The registry record does not report the distribution of responses across all five options, a baseline satisfaction result, or a clinically meaningful threshold. As a result, the reported percentage does not show the full range or degree of participant satisfaction.

The primary population includes randomized participants with at least one post-baseline efficacy assessment, but participant flow and missing Week 16 outcome handling are not reported. The outcome counts do not by themselves explain how many participants lacked an assessment or why. No missing-data sensitivity analyses are reported in the registry record.

The record also lacks the original sample-size rationale, a full statistical analysis plan, and reported procedures for multiplicity. The posted unadjusted comparisons should therefore be interpreted without assuming that an unreported adjustment or prespecified analysis was used. The study reports the primary outcome at Week 16; longer-term outcomes are not reported in the registry record.

Safety reporting is limited to the posted counts by category. The record does not provide serious-event terms, deaths, event timing, or a detailed comparative safety analysis. These limits constrain what can be inferred from the available safety summary.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Study Assessing Patient Satisfaction With LATISSE® for Increasing Eyelash Prominence — NCT01448525.
• Registry record last updated 2013-05-22; status last verified 2013-04.
• Results first posted 2013-05-22.
• 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.

22. Record Summary

The registry record describes a completed randomized, triple-masked, parallel-group phase 4 study with enrollment of 88 participants and a listed condition of hypotrichosis. Study start is recorded as 2011-10 and primary completion as 2012-04.

The study compared once-daily evening application of bimatoprost ophthalmic solution 0.03% with bimatoprost vehicle solution for 16 weeks. The primary outcome was the percentage satisfied or very satisfied with eyelashes overall at Week 16. The posted percentages were 67.4% in the bimatoprost group and 7.1% in the vehicle group.

The registry record also lists a secondary Global Eyelash Assessment outcome. The posted primary comparison is unadjusted. Details of the original sample-size rationale, missing-data handling, multiplicity procedures, and full statistical analysis plan are not reported in the registry record.