Clinical Endpoint Study of Ivermectin 0.5% Lotion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Endpoint Study of Ivermectin 0.5% Lotion (NCT03301649), a randomized phase 3 study. The primary outcome is Percentage of Index Participants Who Were Considered a Treatment Success: PP Population.

2. Clinical Question

3. Trial Design

This was a Phase 3, randomized, double-blind, placebo-controlled, parallel-design, multiple-site clinical study. The registry lists quadruple masking. The study evaluated generic ivermectin lotion 0.5% against SKLICE® (ivermectin) lotion 0.5%, and also included vehicle lotion. Its stated goals were to evaluate therapeutic equivalence and safety for the generic and reference products, with both active treatments also tested for superiority to placebo.

The registry records enrollment of 905 participants and lists head lice as the condition. The study is marked completed. Its recorded start was 2017-10-07 and its primary completion was 2018-03-12. The sponsor is Actavis Inc. These registry entries describe the study’s recorded design and status; they do not, by themselves, establish how participants were recruited, how randomization was implemented, or how masking was maintained. Those operational details are not reported in the registry record.

The described treatment regimen involved one application on Day 1 at home. Participants applied lotion to dry hair, left it in place for 10 minutes, and rinsed it off with warm water. The primary endpoint was assessed at Day 15 ± 2. The main endpoint comparison excluded the vehicle group and evaluated the generic product against the reference product among index participants in the per-protocol population. Secondary results covered all randomized index and non-index participants, using per-protocol and mITT populations. The registry record does not report the original sample-size justification or the detailed analysis plan.

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: Non-enrolled infested participants: Any household member who was infested with lice and agreed to be treated with study drug but did not participate in the study. 912 infested patients were available to participate in the study, one patient was not dispensed study product, 911 patients (905 enrolled + 6 non-enrolled) were treated.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Index participants in PP population. PP population: randomized participants who met all eligibility criteria, applied study drug, were treatment successes/failures and made the final study visit ( Day 15 ± 2), and had no significant 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.

Population: Safety population included all participants who were randomized and received study drug.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Index Participants Who Were Considered a Treatment Success: PP Population, measured over Day 15 ± 2.

The primary endpoint was the percentage of index participants in the per-protocol population considered treatment successes at Day 15 ± 2. Success meant absence of live lice at that assessment. An index participant was defined as the youngest household member randomized into the study. The endpoint therefore describes a binary outcome: each participant was classified as a success or not a success, and the reported group result is a percentage.

This outcome gives a clinically interpretable measure of status at the scheduled follow-up visit. The comparison was designed to assess therapeutic equivalence between generic ivermectin lotion 0.5% and SKLICE® lotion 0.5%; the primary endpoint did not include the vehicle group. The registry’s population definition is important: the primary per-protocol analysis included participants who met eligibility criteria, applied study drug, had a success-or-failure classification, attended the final visit, and had no significant protocol deviations. It is therefore not the same analysis population as all randomized participants.

A binary endpoint simplifies a participant’s observed status into a success classification. That makes the percentage straightforward to interpret, but it does not describe the degree of infestation among participants who were not successes, or changes between visits. Those details are not reported in the registry record. The endpoint also reflects the stated assessment time; it should not be read as a measure of outcomes at other times.

7. Results Posted in the Registry

• Sklice (Ivermectin) Lotion: 89.0% (129/145) versus 90.9% (130/143) on control; risk difference -1.9 percentage points (95% CI -8.9 to 5.0), risk ratio 0.98 (0.91–1.06); unadjusted two-proportion z-test p = 0.584.

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 All Randomized (Index + Non-Index) Participants Who Were Considered a Treatment Success: PP Population

• 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:
  • Sklice (Ivermectin) Lotion: 90.7% (321/354) versus 91.6% (316/345) on control; risk difference -0.9 percentage points (95% CI -5.1 to 3.3), risk ratio 0.99 (0.95–1.04); unadjusted two-proportion z-test p = 0.670.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sklice (Ivermectin) Lotion and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of All Randomized (Index + Non-Index) Participants Who Were Considered a Treatment Success: mITT Population

• 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:
  • Generic Ivermectin Lotion 0.5%: 92.2% (343/372) versus 25.2% (28/111) on control; risk difference 67.0 percentage points (95% CI 58.5 to 75.5), risk ratio 3.66 (2.65–5.04); unadjusted two-proportion z-test p = <0.001.
  • Sklice (Ivermectin) Lotion: 91.3% (347/380) versus 25.2% (28/111) on control; risk difference 66.1 percentage points (95% CI 57.5 to 74.7), risk ratio 3.62 (2.62–4.99); 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 Generic Ivermectin Lotion 0.5% than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Sklice (Ivermectin) Lotion than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Across the secondary outcomes, the overall pattern is that the two active treatments have similar reported success percentages in the per-protocol population, while the mITT comparisons of each active treatment with vehicle are reported as superiority analyses. The secondary endpoints use broader participant coverage than the primary index-participant endpoint, and one is reported in a per-protocol population while another is reported in an mITT population. These distinctions make the secondary results contextual evidence rather than direct substitutes for the primary result.

The primary endpoint addresses therapeutic equivalence between generic ivermectin and SKLICE® in index participants in the per-protocol population. The secondary active-versus-vehicle analyses address a different contrast and population. A result favoring an active treatment over vehicle does not answer whether the generic and reference products meet an equivalence criterion. The secondary per-protocol comparison between active treatments is more closely aligned with the primary question, but it covers all randomized index and non-index participants rather than only index participants.

The record reports two secondary outcomes and includes multiple comparisons. It does not report a multiplicity adjustment plan. When several outcomes or contrasts are examined, the chance of at least one apparently strong finding can increase if each is interpreted as a standalone confirmatory test. For that reason, unadjusted secondary results carry less weight than a prespecified primary analysis, especially when the analysis hierarchy and multiplicity strategy are not reported. The registry’s stated superiority analyses should be distinguished from the unadjusted recalculations, and none should be treated as resolving the missing equivalence margin.

Taken together, the secondary pattern is consistent with the primary active-treatment comparison in the limited sense that the active groups’ reported success rates are similar. It broadens the descriptive context by including non-index participants and vehicle comparisons, but it does not establish identical effects across populations or provide additional precision for the primary estimand. Interpretation should retain the different populations, contrasts, and methods rather than pooling them conceptually.

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

• Percentage of All Randomized (Index + Non-Index) Participants Who Were Considered a Treatment Success: PP Population
• Percentage of All Randomized (Index + Non-Index) Participants Who Were Considered a Treatment Success: mITT Population

9. Statistical Interpretation

10. Statistical Methods Explained

Several statistical ideas help interpret the reported results. The endpoint is a binary percentage: a participant is classified as a treatment success if no live lice are present at the assessment, and the group percentage describes how often that classification occurred. A comparison of percentages can be expressed as a difference in percentage points. The direction of that difference depends on which group is subtracted from which, so the group order must be kept clear when reading a comparison.

What does the confidence interval describe?

A confidence interval gives a range of values compatible with the observed data under the assumptions of the analysis. It communicates precision as well as direction: a narrower interval indicates a more precise estimate, while a wider interval leaves more uncertainty about the size and direction of the underlying difference. For the sponsor’s primary analysis, the reported difference was 1.9 percentage points and the 90% confidence interval ran from -3.9 to 7.8. Because the interval crosses zero, it includes no difference as one value compatible with the data. The interval also includes estimates in both directions. It is not a guarantee that the true value lies inside the displayed limits.

How does equivalence differ from a difference test?

An ordinary test of difference asks whether the data are inconsistent with no difference. Equivalence asks a different question: whether the uncertainty around the estimated difference is sufficiently contained within a prespecified acceptable range. That range is usually essential to interpreting an equivalence claim, because a confidence interval crossing zero alone does not show that two treatments are equivalent. The registry classifies the sponsor analysis as equivalence and reports its estimate and interval, but the acceptable range and its decision rule are not reported in the registry record. The record therefore supports describing the reported analysis, but not independently reconstructing its equivalence decision.

What is the role of the recalculation?

The recalculated comparison is an unadjusted analysis based on posted summary statistics. It is useful as a transparent numerical cross-check, but it does not reproduce every possible feature of the sponsor’s analysis. In particular, the registry does not report a method for the primary sponsor analysis. The recalculation should therefore be read as a supplementary estimate, not as a correction or a substitute. A recalculation based on summary data cannot recover unreported covariate adjustments, stratification, modeling choices, or participant-level details. No discrepancy is flagged in the registry record.

Why do analysis populations matter?

The primary population is per protocol. Its definition includes randomized participants who met eligibility criteria, applied study drug, were classified as successes or failures, completed the final visit at Day 15 ± 2, and had no significant protocol deviations. An analysis restricted by these conditions answers a question about that defined subset. It may differ from an analysis that retains all randomized participants, particularly if exclusions or missing outcomes are related to treatment or outcome. The registry also reports secondary outcomes for all randomized index and non-index participants in per-protocol and mITT populations. These populations are not interchangeable, and their denominators and percentages should not be blended.

What do the superiority results address?

The registry reports Cochran-Mantel-Haenszel superiority analyses for generic ivermectin and SKLICE® against vehicle in the mITT secondary outcome. This method can compare categorical outcomes while accounting for stratification, when strata are part of the analysis. The registry does not identify the strata or provide further method details, so those aspects cannot be assessed from the record. The reported superiority analyses address active treatment versus vehicle; they are distinct from the primary generic-versus-reference equivalence question.

Why should the unadjusted secondary comparisons be treated cautiously?

Multiple outcomes and comparisons create multiple opportunities for a result to appear noteworthy by chance. The registry lists four outcome measures and six analyses, but a multiplicity adjustment strategy is not reported in the registry record. The posted secondary comparisons should therefore be treated as supportive context rather than as isolated confirmatory evidence. The registry’s formal comparisons for the vehicle analyses use a named method, while the simple recalculations are unadjusted. These different methods answer related but not identical statistical questions.

11. Confidence Intervals and Precision

The primary sponsor estimate is a difference of 1.9 percentage points, with a 90% confidence interval from -3.9 to 7.8. This interval is broad enough to include values favoring either group as well as no difference. Its width signals that the observed point estimate should not be treated as a precise measure of the size or direction of any underlying difference. The group percentages, 90.9% for generic ivermectin and 89.0% for SKLICE®, are the observed estimates; the confidence interval expresses uncertainty around the comparison rather than uncertainty around either percentage in isolation.

For an equivalence question, precision is interpreted relative to the acceptable margin. A narrow interval can support equivalence only if it falls within that margin, while an interval that crosses zero can still be too wide to establish equivalence. Since the margin is not reported in the registry record, the interval can be described but not judged against the intended equivalence boundary. The registry’s classification of the analysis as equivalence does not reveal the missing margin.

The recalculated unadjusted interval is also reported as an interval around a difference, and its interpretation depends on the same basic principle: the estimate is uncertain, and an interval including zero does not establish that the groups are equivalent. Confidence intervals are not measures of the probability that one treatment is better, nor do they account automatically for design features or multiplicity that are not incorporated in the analysis. The registry’s sponsor-reported result is the primary reference for the study’s conclusion; the unadjusted recalculation is a supplementary summary of the posted counts.

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 planning figures describe participants per arm for the binary comparisons, not total events. They are illustrations based on the observed effect rather than the trial’s original design assumptions. The calculation assumes two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation. For each comparison, the effect to detect is set to the stated fraction of the observed effect. The original trial’s sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the number of participants per arm that the planning calculation estimates would be needed for an 80% chance of detecting the specified effect under its assumptions. The 90% power column uses a higher chance of detecting that effect and consequently generally calls for more participants per arm. These are conditional planning illustrations, not predictions that a future study will obtain a particular result. For example, the planning entries for the primary comparison range from 3,760 participants per arm for 80% power when using 100% of the observed effect to 14,394 per arm when using 50% of the observed effect. The corresponding 90% entries are 5,033 and 19,269.

Smaller effects are harder to distinguish from random variation, so the planning figures rise as the assumed effect decreases. The displays do not establish that the completed study was adequately or inadequately powered for its original aims, because those aims and assumptions are not reported in the registry record. These figures are not observed power; they are sample-size planning illustrations calculated from the observed effect.

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 = 0.909; treatment proportion p₁ = 0.890; average p̄ = 0.899.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.4254 = 0.8339.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.4252 = 0.3579.
4. n = (0.8339 + 0.3579)² / (-0.0194)² = 3,759.7, rounded up to 3,760 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 <- 0.909090909090909                          # control proportion
p1 <- 0.889655172413793                          # 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(3301649)
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 = 3,760 (80% power), 5,033 (90% power)
 75% of observed effect: n per arm = 6,542 (80% power), 8,757 (90% power)
 50% of observed effect: n per arm = 14,394 (80% power), 19,269 (90% power)
power.prop.test: 3759.7 
Simulated power at n = 3,760 per arm: 0.796 (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. Analyses Reported by the Sponsor

The registry’s sponsor-reported primary analysis is an equivalence analysis. It reports a difference in success percentages of 1.9, with a 90% confidence interval from -3.9 to 7.8. The registry does not report a method for that analysis or the equivalence margin and decision rule. Those missing details limit an independent evaluation of the sponsor’s equivalence conclusion.

The recalculation is a simple unadjusted estimate using the posted summary counts. It does not replace the sponsor’s analysis, because it may not reproduce unreported analysis choices and cannot use participant-level information. The recalculated interval includes no difference, as does the sponsor-reported interval, but this shared feature alone does not establish equivalence. The comparison must also be judged against the prespecified equivalence margin, which is not reported in the registry record.

The discrepancy indicator is false, so the registry information does not flag a disagreement between the posted result and the recalculation. Even so, the sponsor’s own analysis takes precedence as the reported trial analysis. The recalculation is best understood as a transparent cross-check of the summary statistics, with its unadjusted nature kept in view.

15. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary endpoint and two secondary outcomes, and records six analyses. It does not report a multiplicity plan describing whether or how the type I error rate was controlled across outcomes, treatment contrasts, or analysis populations. That omission matters because a collection of statistical tests creates more opportunities for chance findings than a single prespecified test. Without a stated strategy, secondary p-values should not be treated as if they were adjusted confirmatory evidence.

The primary endpoint is reported as an equivalence analysis, while the secondary mITT comparisons against vehicle are reported as superiority analyses using the Cochran-Mantel-Haenszel method. The registry does not provide the complete statistical analysis plan, including detailed model specifications, stratification variables, or a stated hierarchy among tests. It also does not report the equivalence margin or the rule used to decide equivalence. These are important gaps for evaluating how the analyses were planned and interpreted.

Missing-data handling is not reported in the registry record. The primary per-protocol definition requires a final visit and a success-or-failure classification, but the record does not state how participants without an endpoint assessment were handled in each analysis, whether outcomes were imputed, or how sensitivity analyses addressed missingness. The mITT population is named, but its detailed inclusion and outcome rules are not posted by the registry description. Consequently, it is not possible to assess whether missingness could have influenced the estimated treatment comparisons.

Analysis populations answer different questions. The primary result is for index participants meeting the per-protocol criteria. Secondary results include all randomized index and non-index participants in per-protocol and mITT analyses. Differences across those results may reflect population definitions as well as treatment comparisons. The record does not report interim analyses, and their presence or absence should not be inferred. These reporting gaps do not invalidate the posted results, but they limit independent assessment of their statistical context and robustness.

16. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports serious adverse events affecting 0 participants in each listed treatment group: generic ivermectin lotion, vehicle lotion, and SKLICE® lotion. It also reports 0 deaths in each group. For other adverse events, the registry records 31 affected in the generic ivermectin group, 21 in the vehicle group, and 1 in the SKLICE® group. These are the posted counts for the safety record; they should not be interpreted as a comparative safety test without details about event definitions, collection, follow-up, and analysis.

The at-risk counts differ across the listed safety groups: 399 for generic ivermectin, 400 for vehicle, and 112 for SKLICE®. These denominators should be read as recorded rather than combined or treated as interchangeable with the efficacy populations. The registry does not provide event descriptions for the other adverse events or a breakdown by severity, timing, or relatedness. The absence of reported serious events in these groups does not prove that serious harms cannot occur, and these counts alone do not establish that one treatment is safer than another.

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

The results describe treatment success, defined as absence of live lice, at Day 15 ± 2 in specified study populations. In the primary per-protocol analysis of index participants, the reported success percentages were 90.9% for generic ivermectin lotion and 89.0% for SKLICE®. The sponsor reported an equivalence analysis with a difference of 1.9 percentage points and a 90% confidence interval from -3.9 to 7.8. These figures characterize the observed endpoint and its uncertainty in this study.

They do not establish that the two products are identical. Equivalence depends on an acceptable margin and decision rule, which are not reported in the registry record. Nor does a confidence interval that includes zero, by itself, establish equivalence. The record labels the sponsor’s analysis as equivalence, but readers cannot independently judge the margin-based criterion from the information recorded.

The secondary active-versus-vehicle findings address a different question from the primary comparison. They should not be used as a substitute for the generic-versus-reference equivalence analysis. Similarly, the results apply to the defined study populations and assessment time; they do not establish outcomes at other times or in populations not represented by these analyses. The registry’s adverse-event counts provide a limited summary and do not establish comparative safety.

These findings are statistical descriptions of a completed clinical study, not individualized guidance. They should be read alongside the stated populations, endpoint definition, uncertainty interval, and limitations in the registry record. Details needed for a fuller independent assessment—including the equivalence margin, missing-data approach, multiplicity plan, and original sample-size assumptions—are not reported in the registry record.

18. Why This Trial Matters Statistically

This study illustrates why the statistical question must be identified before interpreting a treatment comparison. The primary objective was therapeutic equivalence between generic ivermectin lotion and a reference product, not merely a test for any difference. Equivalence requires a clinically acceptable margin and an interval-based decision rule. The registry reports the sponsor’s estimate and confidence interval but not the margin, showing how a result can be numerically visible while a key part of its interpretation remains unavailable.

The study also demonstrates the importance of matching an estimate to its population. Its primary endpoint concerns index participants in a per-protocol population, while secondary analyses include index and non-index participants and different analysis populations. Those are related, but not identical, estimands. Clear population definitions prevent readers from treating all reported percentages as if they arose from the same group of participants.

Finally, the record separates an active-treatment equivalence question from superiority comparisons against vehicle. These contrasts answer different questions and use different reported analyses. The sponsor result, unadjusted recalculation, secondary tests, and safety counts each have distinct roles. Keeping their scope and limitations explicit is central to sound interpretation of clinical-trial statistics.

19. 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.

Several trial-specific reporting gaps limit interpretation. The registry does not report the equivalence margin or the decision rule for the primary therapeutic-equivalence analysis. Without them, the sponsor’s reported estimate and interval cannot be independently evaluated against the criterion that defines equivalence. The statistical method for the sponsor’s primary analysis is also not stated.

The record does not report the original sample-size justification, analysis plan, multiplicity strategy, or missing-data methods. It does not explain in detail how the mITT population was defined, how participants without a final outcome were handled, or whether sensitivity analyses were conducted. These omissions limit assessment of robustness and of the potential influence of exclusions or missing outcomes.

The registry lists a parallel, randomized, double-blind, placebo-controlled, multiple-site design and quadruple masking, but does not provide operational details about randomization, concealment, or masking procedures. The posted safety summary gives group counts, but not event terms, severity, timing, or relatedness. The other-adverse-event figures therefore have limited interpretive detail.

The primary endpoint is a binary status at Day 15 ± 2. It does not describe the degree of infestation, changes over time, or outcomes beyond that assessment. The per-protocol primary analysis also differs from the broader secondary populations. These are limitations of what the registry record allows readers to assess, rather than evidence that the trial necessarily handled these matters poorly.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Clinical Endpoint Study of Ivermectin 0.5% Lotion — NCT03301649.
• Registry record last updated 2019-12-20; status last verified 2019-12.
• Results first posted 2019-12-20.
• 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.

23. Record Summary

NCT03301649 is a completed Phase 3 randomized, double-blind, placebo-controlled, parallel-design, multiple-site study of generic ivermectin lotion 0.5%, SKLICE® ivermectin lotion 0.5%, and vehicle lotion for head lice. Enrollment is recorded as 905. The primary endpoint was treatment success, defined as absence of live lice at Day 15 ± 2, among index participants in the per-protocol population.

The primary success percentages were 90.9% for generic ivermectin and 89.0% for SKLICE®. The sponsor reported a difference of 1.9 percentage points with a 90% confidence interval from -3.9 to 7.8 in an equivalence analysis. The registry does not report the equivalence margin, missing-data approach, multiplicity plan, or original sample-size justification. The posted results should therefore be interpreted with attention to the endpoint, analysis population, and uncertainty, as well as these reporting limits.