Efficacy, Safety and Tolerability of a Novel Malathion Formulation in Patients 2 Years and Older With Head Lice: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy, Safety and Tolerability of a Novel Malathion Formulation in Patients 2 Years and Older With Head Lice (NCT00963508), a randomized phase 3 study. The primary outcome is Proportion of Index Subjects Free of Any Lice 14 Days After Their Last Treatment in the Modified ITT (LOCF).

2. Clinical Question

3. Trial Design

This was a randomized, single-masked, parallel-group Phase III study sponsored by Sun Pharmaceutical Industries, Inc. The registry lists 403 participants enrolled, a completed status, a start date of 2009-08 and primary completion in 2010-03. The condition was pediculosis. The study compared Malathion Gel with Nix Crème Rinse, with the application durations described as 30 minutes and 10 minutes, respectively. The registry record does not report further details about how randomization was generated or concealed, who was masked, or how adherence to masking was assessed.

The primary efficacy result uses index subjects, defined as the youngest household subject meeting the criteria of having nits and at least 3 live lice. The registry reports 150 such subjects from the 403 randomized participants in its primary efficacy description. The arm-level primary results each include 75 subjects. This subset should not be confused with the broader enrollment or with the safety populations, which include 206 participants in the Malathion Gel group and 197 in the Nix Crème Rinse group.

The registry describes several analysis populations: an efficacy ITT population of index subjects with at least one treatment application; a modified ITT population of treated subjects with at least one post-treatment visit; and a per-protocol population of participants who complied with the protocol and completed required visits. It also refers to missing efficacy data being included first with LOCF and then in a non-LOCF analysis. The primary endpoint title specifies mITT (LOCF), while its description refers to Treatment Success in the Efficacy ITT (LOCF). That difference in labeling makes the exact population label less clear from the registry record. The trial's original sample-size assumptions and detailed analysis plan 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: Efficacy: index subjects who had at least one application of treatment mITT: treated subjects who had at least one post-treatment visit Subjects with missing efficacy data were included first LOCF and then with non-LOCF PP: subjects who complied with the protocol, completed all required visits Safety: all subjects who had at least one treatment

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 Proportion of Index Subjects Free of Any Lice 14 Days After Their Last Treatment in the Modified ITT (LOCF), measured over 3 weeks.

The primary endpoint is the proportion of index subjects free of any lice 14 days after their last treatment. The registry describes treatment success as assessed at the Day 14 visit for subjects treated on Day 1 only, or at the Day 21 visit for subjects treated on Day 1 and Day 7. The registered timeframe is 3 weeks. This is a binary outcome: each subject is classified according to whether the stated success condition was met, and the group result is expressed as a percentage of subjects.

Using a defined post-treatment assessment makes it possible to compare the observed success proportions between the randomized groups at a stated point in the treatment schedule. Restricting the primary efficacy assessment to index subjects also gives the outcome a household-based definition: the index subject is the youngest household member meeting the lice and nit criteria. The endpoint is not a count of lice removed or a time-to-event measure. It represents the proportion meeting the registry's success definition at the specified assessment.

The primary endpoint title calls the outcome the proportion free of any lice, while the description calls it Treatment Success. The registry does not provide additional detail in this record about the operational criteria used to classify success beyond the stated lice-free wording and assessment timing. The analysis uses a modified ITT (LOCF) label in the endpoint title, while the description also names an Efficacy ITT (LOCF) analysis. That distinction should be kept in mind when interpreting exactly which analysis population underlies the posted percentages.

7. Results Posted in the Registry

• Nix Crème Rinse: 45.3% (34/75) versus 86.7% (65/75) on control; risk difference -41.3 percentage points (95% CI -55.0 to -27.7), risk ratio 0.52 (0.40–0.68); 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.

Proportion of Subjects Who Were Considered a Treatment Success 14 Days After Their First Treatment in the Modified ITT (LOCF).

• 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:
  • Nix Crème Rinse: 55.4% (102/184) versus 89.9% (178/198) on control; risk difference -34.5 percentage points (95% CI -42.8 to -26.1), risk ratio 0.62 (0.54–0.71); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically lower for Nix Crème Rinse than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The registry posts one secondary outcome: treatment success 14 days after the first treatment in the modified ITT (LOCF) population. Its overall direction is consistent with the primary result, with a higher posted success proportion in the Malathion Gel group than in the Nix Crème Rinse group. This offers supporting context, but it does not represent an independent replication of the primary finding.

The secondary and primary outcomes differ in assessment timing: the secondary endpoint is anchored to the first treatment, while the primary endpoint is assessed 14 days after the last treatment. The population descriptions and analysis labels also differ. These distinctions mean the secondary finding should be interpreted as a related but separate outcome, not as an exact repeat of the primary analysis in an identical set of participants.

Only one secondary endpoint is posted in the registry record, even though the record notes 2 outcome measures and 2 analyses. The registry does not report a prespecified multiplicity adjustment or a testing hierarchy. General statistical explanation: examining multiple outcomes can increase the chance of finding an apparently strong result by chance if each is tested without accounting for the set of tests. An unadjusted secondary p-value therefore carries less weight than a primary result when no multiplicity approach is described. The secondary pattern may reinforce the direction of the primary observation, but it should not be used alone to establish the strength or robustness of the evidence.

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

• Proportion of Subjects Who Were Considered a Treatment Success 14 Days After Their First Treatment in the Modified ITT (LOCF).

9. Statistical Interpretation

10. Statistical Methods Explained

The primary and secondary outcomes are binary: each participant either meets the specified treatment-success definition or does not. The reported percentages describe the fraction meeting that definition within each analysis group. General statistical explanation: a comparison of proportions is often expressed as a risk difference, which subtracts one group's proportion from the other's. The sign depends on the order of the groups. In the posted primary recalculation, the contrast is Nix Crème Rinse minus Malathion Gel, so a negative estimate corresponds to a lower observed proportion in the Nix group.

What does the confidence interval describe?

General statistical explanation: a confidence interval gives a range of values compatible with the observed data under the method used. It communicates uncertainty around an estimated group difference; it is not a range containing a known, fixed effect with certainty. For the primary recalculated risk difference, the interval runs from -0.550 to -0.277. Because the interval is entirely below zero, the recalculated estimate is compatible with a lower success proportion in the Nix group under this contrast and method. This interval is tied to the posted summary statistics and does not incorporate uncertainties that may arise from unreported design or analysis details.

How should the p-values be read?

General statistical explanation: a p-value measures how unusual data at least as inconsistent with a null comparison would be if the null model and its assumptions were correct. It is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of a difference. The recalculated primary comparison has an unadjusted p-value of <0.001. The sponsor's analysis reports p < 0.001 using a two-sided t-test. These p-values come from different reported analyses and should not be treated as interchangeable measures of effect magnitude. The registry's secondary analysis reports a two-sided t-test with p < 0.001; that result is also unadjusted.

What do the analysis populations mean?

The registry distinguishes an efficacy ITT population, a modified ITT population, and a per-protocol population. The efficacy ITT description concerns index subjects who had at least one application of treatment. The mITT description concerns treated subjects with at least one post-treatment visit. The per-protocol description concerns participants who complied with the protocol and completed required visits. The primary endpoint title specifies mITT (LOCF), while its descriptive text identifies Treatment Success in the Efficacy ITT (LOCF). Since those labels are not fully aligned in the record, readers should not assume that all these populations are interchangeable.

LOCF means last observation carried forward: when an efficacy value is missing, an earlier observed value may be used in its place. General statistical explanation: this approach imposes an assumption about how the unobserved outcome relates to the last observed assessment. Its suitability depends on the pattern and reasons for missingness, among other factors. The record says missing efficacy data were included first with LOCF and then with non-LOCF analyses, but it does not report the missing-data counts or the results of those alternative analyses. The extent to which missing-data choices affect the finding is therefore not reported in the registry record.

What is known about the sponsor's test?

The sponsor's primary analysis is listed as a two-sided t-test, but the record does not identify the exact variable submitted to that test, any covariate adjustment, or additional model details. The recalculation uses the posted group counts and proportions to estimate an unadjusted risk difference and interval. These are distinct statistical approaches and summaries. The sponsor's test result is the sponsor-reported analysis; the recalculation offers a transparent comparison based on the posted summary statistics, rather than replacing the sponsor's analysis.

General statistical explanation: the t-test is ordinarily used to compare means, whereas a binary endpoint is naturally described by proportions. Without fuller details about the sponsor's analysis, the registry record does not establish how its t-test was applied to this endpoint. The record lists no adjustment variables for the recalculation. Random allocation supports a group comparison, but it does not by itself resolve uncertainty about missing outcomes, population definitions, or the analysis choices used after enrollment.

Why does over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variability is greater than a statistical model expects. It can make standard errors too small and confidence intervals too narrow if the model does not allow for that extra variability. For an outcome summarized as a binary proportion, the posted data do not supply a dispersion estimate, and the reported recalculation is based on group-level counts and proportions. The registry record does not report an over-dispersion assessment or a model adjustment for it. This concept is relevant when interpreting model-based analyses, but the record does not establish that over-dispersion affected this trial's reported result.

The trial's detailed statistical analysis plan, the original sample-size justification, interim analyses, and any prespecified multiplicity procedure are not reported in the registry record. The planning illustrations associated with the observed effect are separate from the original study design. They are not evidence that the actual design used those assumptions.

11. Confidence Intervals and Precision

The recalculated primary risk difference is -0.413, with a confidence interval from -0.550 to -0.277. This interval gives a sense of precision for the contrast between the posted proportions under the unadjusted recalculation. Its endpoints are both negative, so the interval does not include zero for the stated Nix-minus-Malathion contrast. The interval is not a guarantee about the true effect, and it does not account for unreported sources of uncertainty such as the impact of missing data or ambiguity in the population label.

The primary percentages are based on 75 subjects in each arm. The registry also reports 150 index subjects from 403 randomized participants in the primary efficacy description. These counts clarify that the primary comparison is not based on all enrolled participants. The record does not report a sponsor confidence interval for the primary result, so the recalculated interval is the only interval available in the posted statistics.

For the secondary endpoint, the recalculated risk difference is -0.345, with a confidence interval from -0.428 to -0.262. As with the primary contrast, the comparison is expressed as Nix Crème Rinse minus Malathion Gel. That interval describes the secondary calculation only and should not be taken as a substitute for the primary estimate. The registry does not report sponsor confidence intervals for either result.

General statistical explanation: narrower confidence intervals indicate greater precision in the estimate, while wider intervals indicate more uncertainty. Precision depends on the amount of information and the statistical assumptions used. A confidence interval speaks to the uncertainty around an estimate, not whether the outcome is important or whether the analysis population and missing-data assumptions are appropriate.

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 are participants per arm, not total events. They are illustrations calculated from the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning scenario uses the stated fraction of the observed effect as the effect to detect. For example, the rows for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect show how the planning count changes as the assumed effect becomes smaller.

The 80% power column gives the participants per arm for a planning scenario designed to have an 80% chance of detecting the specified effect under the stated assumptions. The 90% power column gives the corresponding participants per arm for a 90% chance. These are planning concepts conditional on the assumptions; they do not tell how likely the observed result was to occur after the trial was completed. Smaller effects need more participants per arm to detect under the same assumptions.

The planning illustrations are based on the observed results, not the trial's own original design assumptions, which are not reported in the registry record. This is not observed power. It is a way to understand the approximate sample size associated with hypothetical planning choices, rather than a measure of the study's success or evidence that the original design had those properties.

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 = 0.867; treatment proportion p₁ = 0.453; average p̄ = 0.660.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6699 = 1.3130.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6028 = 0.5073.
4. n = (1.3130 + 0.5073)² / (-0.4133)² = 19.4, rounded up to 20 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 <- 0.866666666666667                          # control proportion
p1 <- 0.453333333333333                          # 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(963508)
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 = 20 (80% power), 26 (90% power)
 75% of observed effect: n per arm = 33 (80% power), 43 (90% power)
 50% of observed effect: n per arm = 66 (80% power), 87 (90% power)
power.prop.test: 19.4 
Simulated power at n = 20 per arm: 0.833 (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 sponsor's primary analysis is reported as a two-sided t-test with p < 0.001. The registry does not provide a sponsor-reported effect estimate or confidence interval for that analysis. The recalculated analysis uses the posted group counts and proportions to report a risk difference of -0.413, a confidence interval from -0.550 to -0.277, and an unadjusted p-value of <0.001. The recalculated contrast is explicitly oriented as Nix Crème Rinse minus Malathion Gel.

These results are not competing versions of the same statistic: the sponsor's reported test and the recalculated risk difference summarize the comparison in different ways. The registry-derived calculations flag no discrepancy. The sponsor's own analysis takes precedence if a discrepancy is present, but no such discrepancy is flagged for this result. The difference in reported p-value thresholds alone does not show a conflict, and neither p-value describes the size of the group contrast.

The registry record does not report enough detail to reproduce the sponsor's test, including the exact quantity tested and any additional analysis specifications. The recalculation should therefore be read as a simple unadjusted re-analysis of the posted summary statistics, not as a reconstruction of the sponsor's full statistical analysis.

15. Multiplicity, Missing Data and Analysis Populations

The primary endpoint is identified, and the registry also posts a secondary treatment-success endpoint. The record does not report whether the trial specified a formal testing hierarchy or a multiplicity adjustment for the outcomes. Without that information, the secondary p-value should be read as unadjusted, and the record does not establish how the sponsor intended to control the chance of false-positive findings across outcomes.

Missing efficacy data were handled in the posted description using LOCF, followed by a non-LOCF analysis. The registry record does not report how many outcomes were missing, the reasons for missingness, or the numerical results of the non-LOCF analysis. General statistical explanation: missing-data methods rely on assumptions about the outcomes that were not observed. LOCF uses an earlier value to stand in for an unavailable later assessment; this may not represent what would actually have been observed. Without missingness details and sensitivity results, the influence of this choice cannot be assessed.

Analysis populations are also described with more than one label. The primary endpoint title refers to mITT (LOCF), while the description refers to Treatment Success in the Efficacy ITT (LOCF). The registry separately defines mITT as treated subjects with at least one post-treatment visit and efficacy ITT as index subjects with at least one application. It also defines a per-protocol population based on protocol compliance and completed required visits. The record does not make clear which of these labels precisely governs the posted primary percentages.

The registry record does not report the original sample-size justification, interim analyses, the full statistical analysis plan, or details about how protocol deviations were handled. These omissions limit assessment of whether the analyses followed prespecified procedures and how robust the results are to alternative populations or missing-data assumptions. They do not change the posted numerical results, but they restrict what can be concluded about the analysis process.

16. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports 0 serious adverse events among 206 participants at risk in the Malathion Gel group and 0 among 197 participants at risk in the Nix Crème Rinse group. These are the serious-event counts recorded for the stated safety populations. They should be read as no serious adverse events reported in those groups, not as proof that serious events are impossible or that risks are identical.

For other adverse events, the registry reports 21 affected participants among 206 at risk in the Malathion Gel group and 37 among 197 at risk in the Nix Crème Rinse group. The record does not provide event-term details in the safety summary. It also does not report deaths: the death fields are not populated, so deaths are not reported in the registry record rather than confirmed as zero.

These safety counts use broader group totals than the primary efficacy analysis, which is reported for index subjects. The registry record does not provide event severity or exposure-adjusted comparisons beyond the serious and other adverse-event counts. Accordingly, these figures describe what was posted, but do not by themselves establish comparative safety.

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

The posted primary results show different observed treatment-success proportions for the two groups among the analyzed index subjects. The Malathion Gel group had a reported proportion of 86.67%, and the Nix Crème Rinse group had 45.33%. The recalculated risk difference and its confidence interval indicate that, under the stated contrast and unadjusted method, the observed difference is not close to zero. The sponsor's reported two-sided test also has a small p-value. These are statistical descriptions of the registry results, not medical advice.

The result applies to the endpoint definition and analysis population recorded for the trial: index subjects meeting the household criteria, with success assessed 14 days after the last treatment. It does not automatically describe all participants, all people with head lice, or outcomes assessed at other times. The primary population label is not entirely consistent between the endpoint title and description, and the record does not show how many efficacy observations were missing or how the non-LOCF analysis compared.

A difference in observed proportions does not explain why the groups differed. It does not show which treatment features, participant characteristics, adherence, or other factors contributed to the result. Randomization is a design feature intended to support fair group comparisons, but the registry does not report enough detail to assess every aspect of randomization or analysis. The posted result also does not establish whether the same pattern would occur in other settings or populations.

The secondary outcome has a direction consistent with the primary result, but its treatment timing and analysis population differ, and the registry does not report a multiplicity procedure. The safety information is limited to posted counts of serious and other adverse events, without detailed event terms in the record. In combination, the findings describe efficacy and safety observations within this trial; they do not by themselves resolve broader questions about clinical use, comparative benefit, or harms.

18. Why This Trial Matters Statistically

This trial illustrates why the estimand and population behind a percentage matter. The enrollment was 403, but the primary efficacy description identifies 150 index subjects, and the arm-level primary results include 75 subjects per group. The outcome therefore concerns a defined household index case rather than every randomized participant. Reading the percentages without that context could make the result appear broader than the registry supports.

It also shows the value of keeping the effect estimate distinct from a p-value. The recalculated risk difference and confidence interval describe the direction and range of the group contrast, while the sponsor's two-sided test reports a p-value without an estimate or interval. Those summaries answer related but different statistical questions. The recalculation makes the contrast's orientation explicit, which is essential when a negative risk difference is reported.

The record further illustrates how analysis labels, missing-data methods, and multiplicity affect interpretation. The primary endpoint title and description use different population labels, and the record notes LOCF and non-LOCF analyses without posting their comparative results. It lists a secondary endpoint but does not report a multiplicity strategy. These details do not erase the posted findings, but they help define the limits of what the findings can establish.

Finally, planning illustrations based on the observed effect must be kept separate from the actual study design. The original sample-size assumptions are not reported in the registry record. Planning calculations can show how assumptions about the effect and desired power relate to participant requirements, but they cannot reconstruct the trial's original rationale or serve as observed power.

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.

The registry record leaves several trial-specific uncertainties. The primary endpoint title identifies an mITT (LOCF) population, while its description refers to Treatment Success in the Efficacy ITT (LOCF). The record defines these populations differently, so the exact population underlying the posted primary result is not completely clear. It also notes a non-LOCF analysis but does not report that result, the number of missing outcomes, or the reasons outcomes were missing.

The primary description says 150 index subjects were drawn from 403 randomized participants, while the efficacy arms contain 75 subjects each. This makes clear that the primary efficacy result is based on a selected index-subject population. The registry does not provide additional detail about the number of households represented or how household clustering was considered in the analysis. No inference about such adjustment should be made from the record.

The sponsor's analysis is listed as a two-sided t-test, but the record does not specify the exact test input, covariate adjustments, or full analysis procedure. The recalculation is unadjusted and based on posted summary statistics. The original sample-size assumptions, interim analyses, detailed protocol, and prespecified multiplicity procedure are not reported in the registry record.

The safety summary gives serious and other adverse-event counts but does not provide event terms in the posted summary, and deaths are not reported in the registry record. The study description identifies single masking but does not specify who was masked or how masking was maintained. These reporting limits constrain assessment of safety, bias, and the robustness of the efficacy analyses. They should be distinguished from the numerical results that the registry does report.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Efficacy, Safety and Tolerability of a Novel Malathion Formulation in Patients 2 Years and Older With Head Lice — NCT00963508.
• Registry record last updated 2014-06-13; status last verified 2014-05.
• Results first posted 2014-06-13.
• 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

NCT00963508 is a completed randomized, single-masked, parallel Phase III study sponsored by Sun Pharmaceutical Industries, Inc. It enrolled 403 participants and compared Malathion Gel 0.5%, applied for 30 minutes, with Permethrin 1% rinse (Nix Crème Rinse), applied for 10 minutes. The study concerned pediculosis in patients 2 years of age and older.

The primary outcome was the proportion of index subjects free of any lice 14 days after their last treatment, with a registered timeframe of 3 weeks. The posted primary proportions were 86.67% for Malathion Gel and 45.33% for Nix Crème Rinse, based on 75 subjects per group. The registry also posts one secondary treatment-success endpoint, assessed 14 days after the first treatment.

The primary recalculation reports a risk difference of -0.413 for Nix Crème Rinse minus Malathion Gel, with a confidence interval from -0.550 to -0.277 and p <0.001. The sponsor reports a two-sided t-test with p < 0.001. The record reports 0 serious adverse events in each safety group, while other adverse events affected 21 of 206 and 37 of 197 participants, respectively. Important details about the original design assumptions, missing-data results, and multiplicity procedures are not reported in the registry record.