A Study of Acetyl Hexapeptide-8 (AH8) in Treatment of Blepharospasm: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Acetyl Hexapeptide-8 (AH8) in Treatment of Blepharospasm (NCT00942851), a randomized phase 1, phase 2 study. The primary outcome is Time Until Jankovic Blepharospasm Rating Scale (JBRS) Reverts Back to Baseline.

2. Clinical Question

This question concerns the added contribution of the cream in a population already receiving BoNT, not a comparison of AH8 with BoNT or with no treatment. Participants were described as having prior successful BoNT treatment, and the registry summary says they received injections using previously effective doses and sites. The trial therefore addresses AH8 cream as an addition to that treatment regimen.

The registry lists 24 enrolled participants, while the posted primary-outcome groups contain 12 in the AH8 group and 11 in the placebo group. The reason the outcome groups account for fewer participants than the enrollment figure is not reported in the registry record. This distinction matters when interpreting the analysis: enrollment is a trial-level count, whereas the posted group counts describe the participants included in the reported outcome summaries.

3. Trial Design

The registry classifies the study as phase 1/phase 2, randomized, triple-masked, and parallel-group. It lists 24 participants enrolled and describes adults with blepharospasm who had been receiving successful BoNT injections as eligible. The brief summary identifies focal dystonia as the condition. The study is marked completed.

Participants were assigned to AH8-containing topical cream or cream without AH8. The summary describes BoNT injections at the same sites and doses that had previously worked for each participant, followed by instructions for applying the assigned cream. It also describes a return visit one month after the first visit for a neurological examination, questions about symptoms, and assessment of side effects. The summary says participants could be involved for a maximum of seven months; later visit details are not reported in the registry record.

The primary outcome groups contain 12 participants assigned to AH8 and 11 assigned to placebo. For the primary result, the registry posts an average and standard deviation for each group. The trial enrollment figure is 24, and the reason the primary-outcome group counts do not account for all enrolled participants is not reported in the registry record. The safety figures use 12 participants at risk in each group.

The record lists two secondary outcomes: change in the Jankovic Blepharospasm Rating Scale (JBRS) at three months and percentage change in the Blepharospasm Disability Scale (BDS) at three months. It does not report a formal analysis plan, the original sample-size justification, analysis populations, or the details of masking procedures in the registry record. The design labels indicate random assignment, three-way masking, and a parallel comparison, but the record does not identify which roles were masked.

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

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 Time Until Jankovic Blepharospasm Rating Scale (JBRS) Reverts Back to Baseline, measured over 3-7 months.

The primary endpoint is the time until the JBRS returns to the participant’s baseline value, reported in months over a timeframe of three to seven months. The JBRS measures blepharospasm severity on a scale from 0, indicating no symptoms, to 8, indicating the most severe symptoms and functional blindness. It includes blink frequency and severity of abnormal eye closure.

In the registry’s description, baseline is measured before the topical intervention, and the JBRS is followed over time. Returning to the baseline score is described as a loss of benefit from the BoNT injection. The time until that return is therefore intended to indicate whether the topical intervention adds time before the score reaches its baseline level again. A longer average time represents a later return to baseline on this measure, but interpretation still depends on the difference between groups and the precision of that estimate.

The outcome is a continuous measure summarized by a mean and standard deviation for each group. The posted mean is 3.71 months in the AH8 group and 3.03 months in the placebo group. The registry does not report additional details about how the time was determined for participants whose JBRS did not return to baseline during follow-up, or how such observations were handled analytically.

7. Results Posted in the Registry

• Active Ingredient- AH8: mean 3.71 versus 3.03 on control; difference 0.68 (95% CI -0.17 to 1.53), standardized effect d = 0.63; z-test p = 0.116.

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.

Change in the JBRS at 3 Months

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Active Ingredient- AH8: mean 1.09 versus 0.92 on control; difference 0.17 (95% CI -1.12 to 1.46), standardized effect d = 0.11; z-test p = 0.796.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Active Ingredient- AH8 and the control. The interval gives the range of effects that remain compatible with the data.

% Blepharospasm Disability Scale (BDS) Change at 3 Months

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Active: mean 30.89 versus 32.32 on control; difference -1.43 (95% CI -29.43 to 26.57), standardized effect d = -0.04; z-test p = 0.920.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Active and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes assess the same broad clinical area using two different summaries: change in JBRS at three months and percentage change in BDS at three months. The posted group comparisons do not show a precise separation; both confidence intervals include zero, and both unadjusted p-values are large. Taken together, the secondary results do not clearly reinforce the primary outcome’s positive point estimate. They also do not establish that the groups are equivalent, because the intervals allow differences in either direction.

The secondary outcomes are related to the primary question but measure it differently. The primary outcome concerns time until the JBRS returns to baseline, while one secondary outcome concerns JBRS change at a fixed time and the other concerns percentage change in disability scale score. Agreement across distinct measures can be informative, but disagreement or imprecision can arise because the measures capture different aspects of symptoms and function, or because estimates are noisy. The registry record does not report analyses explaining the relationships among these measures.

General explanation: results from multiple outcomes need to be interpreted with attention to multiplicity. When several comparisons are examined, the chance of at least one apparently unusual result can increase unless the analysis plan accounts for the number and role of the comparisons. Conversely, a lack of statistically distinct secondary results does not prove an absence of an effect. The registry record does not report a multiplicity adjustment or a prespecified hierarchy for interpreting the secondary outcomes.

The secondary outcomes therefore offer supporting descriptive context, but they carry less weight than a clearly specified, adequately powered primary analysis. The posted record contains no reported analyses for these outcomes, and the comparisons are unadjusted. They should not be treated as independent confirmation of the primary finding or as a substitute for a reported analysis plan. Their main contribution is to show that the available secondary summaries remain uncertain and do not provide a clear, consistent separation between the groups.

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

• Change in the JBRS at 3 Months
• % Blepharospasm Disability Scale (BDS) Change at 3 Months

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous, so the registry summarizes it with a mean and standard deviation for each group. A mean describes the group’s average observed time until the JBRS returned to baseline. A standard deviation describes how dispersed individual observations were around that group average. The AH8 group mean was 3.71 months, with a standard deviation of 1.48; the placebo mean was 3.03 months, with a standard deviation of 0.23.

What does a mean difference represent?

General explanation: a mean difference subtracts one group’s average from the other group’s average, using the stated comparison direction. The posted estimate is 0.68 months for AH8 relative to placebo. It summarizes the separation between the group averages, not the experience of every participant. Individual outcomes can fall above or below their group mean, and the group summaries do not show the full distribution of observations.

The registry also posts a standardized difference, d = 0.628. General explanation: a standardized difference expresses the mean separation relative to a pooled estimate of variability, putting the difference on a scale that is not tied to the outcome’s original unit. It can help describe the size of a group contrast in relation to spread, but it does not remove uncertainty or compensate for a small study. The registry’s posted effect-size value is descriptive; it is not a separate measure of clinical importance.

Why do variability and sample size matter?

General explanation: greater variability makes group averages less precise when the number of observations is limited. The primary-outcome standard deviations differ substantially between the groups. That difference is important because a pooled variability estimate can conceal unequal spreads, and estimates of variability based on small groups may themselves be unstable. The registry record does not report an adjusted or alternative analysis addressing unequal variances, nor does it give participant-level data with which to assess the distribution.

The unadjusted comparison posts a confidence interval and p-value alongside the mean difference. General explanation: a confidence interval gives a range of values compatible with the data and the method used to form the interval, while a p-value describes how unusual the data would be under a specified no-difference model and analysis. Neither statistic gives the probability that a treatment is effective, and neither alone establishes the importance of a difference. The primary interval crosses zero, and the unadjusted p-value is 0.116, so the posted summaries do not give a precise distinction between a difference in either direction and no difference.

The posted p-value and interval are unadjusted comparisons based on summary statistics. They are not reported as a sponsor-conducted model or as an analysis adjusted for baseline characteristics, repeated measurements, or other factors. No reported analysis method, test specification, covariate plan, or analysis population is available in the registry record. The absence of those details means the comparison should not be attributed to a particular modeling strategy beyond its description as an unadjusted mean comparison.

What can the secondary comparisons add?

The secondary outcomes are also continuous measures summarized with group means and standard deviations. Change in JBRS from baseline to three months has a posted mean difference of 0.17 points, with a confidence interval from -1.116 to 1.456 and an unadjusted p-value of 0.796. The BDS percentage-change comparison has a posted mean difference of -1.43, with a confidence interval from -29.43 to 26.57 and an unadjusted p-value of 0.92. Both intervals cross zero. These are posted comparisons, not reported sponsor analyses.

General explanation: confidence intervals that cross zero indicate that the data and interval method are compatible with no group difference, as well as some values on either side. Wide intervals signal limited precision. Secondary outcomes can help describe whether multiple measures tell a consistent story, but they do not automatically confirm a primary result. Their interpretation also depends on how many outcomes were assessed and whether the analysis plan controlled the chance of false-positive findings; that plan is not reported in the registry record.

The record lists no reported analyses for the secondary outcomes. The simple comparisons should therefore be treated as descriptive evidence from the posted summaries, rather than as a complete account of prespecified, adjusted, or sensitivity analyses. General explanation: a sensitivity analysis checks whether an inference changes under reasonable alternative assumptions or methods. Such analyses can be useful when outcomes are incomplete or variability differs, but they are not reported in the registry record.

11. Confidence Intervals and Precision

The primary mean difference is 0.68 months, and its confidence interval extends from below zero to 1.528 months. This interval includes no difference. It also includes values in which the average time is shorter in the AH8 group and values in which it is longer. The range is therefore not narrow enough to pin down the direction or size of the underlying difference with precision.

General explanation: a confidence interval describes uncertainty around an estimate under the method used to construct it. It is not a range containing a fixed proportion of individual participant outcomes, and it does not assign a probability to a particular treatment effect. A confidence interval that crosses zero does not prove that the groups are identical; it indicates that no difference remains among the values compatible with the interval as well as differences in both directions.

The primary groups are small, and the observed standard deviations are different: 1.48 months for AH8 and 0.23 months for placebo. These features make the group comparison sensitive to the observed data and contribute to caution in interpreting the estimate. The registry does not post participant-level values, missing-data details, or alternative precision estimates, so the effect of individual observations and analysis choices cannot be assessed from the record.

The secondary intervals are also broad relative to their point estimates: the JBRS change interval runs from -1.116 to 1.456 points, and the BDS percentage-change interval runs from -29.43 to 26.57. Both include zero and allow differences in either direction. Across the primary and secondary outcomes, the estimates are not precise enough to support a confident statement about the size of a group difference. The absence of reported analyses further limits assessment of whether alternative methods would materially change the intervals.

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 based on the observed primary effect, not the original trial design. The planning assumptions are a two-sided significance level of 0.05, equal allocation between two groups, and a normal approximation. Each row considers detecting a stated fraction of the observed effect. The original trial’s own sample-size assumptions and justification are not reported in the registry record.

These figures are participants per arm, not total participants or total events. For planning to detect 100% of the observed effect, the illustration gives 40 participants per arm for 80% power and 54 participants per arm for 90% power. For 75% of the observed effect, the corresponding figures are 71 and 95 participants per arm. For 50% of the observed effect, they are 160 and 214 participants per arm.

General explanation: power is the chance that a planned statistical test will detect a specified effect under the assumptions used in the calculation. The 80% column and 90% column represent two different target chances of detecting the assumed effect, if that effect were real and the planning assumptions held. A higher target power requires more participants. Smaller effects are harder to distinguish from random variation, so planning to detect a smaller fraction of the observed effect requires more participants per arm.

These counts are not observed power and do not describe the probability that the completed trial produced a correct conclusion. They are hypothetical planning quantities generated using the observed effect as a reference. Because observed effects in small studies can be unstable, the illustrated counts should be read as conditional examples, not as a recommendation or as evidence that the trial was originally designed around these assumptions. The registry record does not report the trial’s original power target or planned effect size.

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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.680; pooled standard deviation σ = 1.083.
2. n = 2 × (1.96 + 0.842)² × 1.083² / 0.680² = 39.8, rounded up to 40 participants per arm for 80% power.

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

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.68                      # observed difference in means
sigma <- 1.0828401807944                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

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

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(942851)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 40 (80% power), 54 (90% power)
 75% of observed effect: n per arm = 71 (80% power), 95 (90% power)
 50% of observed effect: n per arm = 160 (80% power), 214 (90% power)
power.t.test: 40.8 
Simulated power at n = 40 per arm: 0.790 (20000 replicates)

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

14. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and two secondary outcomes. It does not report a plan for controlling multiplicity, a hierarchy among the outcomes, or a rule for interpreting secondary results if the primary result is uncertain. The reported secondary comparisons are unadjusted. General explanation: when multiple outcomes are tested, evaluating each without accounting for the number of tests can increase the chance of finding an apparently notable result by chance. The absence of a reported multiplicity plan limits interpretation of the secondary p-values, whether they are small or large.

Missing-data methods and the amount and pattern of missing outcome data are not reported in the registry record. The record also does not describe how participants with incomplete follow-up, or observations for which return to baseline was not recorded, were handled. These details matter because complete-case summaries can differ from results that account for missing observations, especially when missingness is related to outcomes. No assumptions about missingness or imputation can be inferred from the posted summaries.

The analysis populations are not reported in the registry record. In particular, the record does not state whether the primary comparison followed an intention-to-treat approach, included only participants with an observed endpoint, or used another population definition. The registry lists 24 enrolled participants, while the primary outcome groups contain 12 and 11 participants. The reason for this difference is not reported. Safety figures list 12 at risk in each group, which also differs from the placebo primary-outcome count; the reason is not reported.

The record contains no reported analyses for the primary or secondary outcomes, no detailed model specification, and no reported interim-analysis plan. These omissions do not establish that such procedures did or did not occur; they mean the registry record does not describe them. Consequently, the posted summary comparisons cannot be checked against a documented analysis plan, and their sensitivity to missing data, analysis-population definitions, multiplicity choices, or other analytic decisions cannot be evaluated from the record.

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 1% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events among 12 participants at risk in the AH8 group and zero among 12 at risk in the placebo group. It also reports two other, non-serious adverse events in each group, with 12 participants at risk in each. These are counts in the posted safety record; the terms describing the individual events are not listed.

General explanation: an event count is not the same as a rate of all possible harms, and a small group can provide limited information about uncommon events. These figures describe what was recorded for the stated groups and do not establish that no other events occurred. The registry does not report deaths, so deaths are not reported in the registry record. It also does not provide additional detail about event severity, timing, relationship to intervention, or how events were collected.

The safety denominator is 12 participants in each group, while the primary-outcome group counts are 12 for AH8 and 11 for placebo. The reason for the difference in the placebo counts is not reported in the registry record. The adverse-event figures should therefore be read as their own posted summary, without assuming that they refer to exactly the same analysis population as the primary endpoint.

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

The posted primary result is an average difference of 0.68 months in time until JBRS returned to baseline, with the AH8 group mean higher than the placebo group mean. The confidence interval includes zero and spans values on either side, while the unadjusted p-value is 0.116. The result is therefore compatible with a range of possible group differences and does not precisely determine their direction or size.

This does not show that AH8 has no effect, just as the positive point estimate does not establish that AH8 adds benefit. The registry’s endpoint description gives the clinical interpretation of a later return to baseline, but a group-average comparison in a small study is not a definitive measure of what an individual participant would experience. The posted outcome summaries also do not provide participant-level trajectories or details of missing observations.

The secondary outcomes offer additional measurements, but their estimates are also uncertain and their confidence intervals include zero. The registry does not report a multiplicity plan, analysis populations, missing-data methods, or sponsor analyses. Those limitations prevent a complete assessment of how the posted comparisons relate to the original statistical plan or how robust they are to alternative analytic choices.

General explanation: statistical evidence and clinical importance are distinct. A numerical difference may be estimated with uncertainty, and deciding whether a difference matters clinically requires context about the measure, its interpretation, and appropriate thresholds. The registry does not report a threshold for a meaningful change in the primary endpoint or the secondary scales. The results should therefore be read as descriptions of the posted data and their precision, not as medical advice or a treatment recommendation.

17. Why This Trial Matters Statistically

This study illustrates how a randomized comparison can be informative while remaining statistically uncertain. Random assignment and a parallel-group structure are intended to support a fair comparison between groups, and triple masking may help limit some influences on assessments and behavior. The registry record does not identify which roles were masked or describe the masking procedures, so the labels alone do not establish how those protections operated in practice.

The primary outcome is framed around time until a scale returns to baseline after BoNT injections. That makes the estimand different from a simple symptom score at one visit: it concerns how long the score remains away from baseline. The posted mean difference is positive, but the interval crosses zero and extends to a materially larger positive value. This is a useful example of why the estimate, its uncertainty, and the outcome’s definition should be interpreted together.

The small outcome groups and unequal observed variability make precision especially important. A point estimate can appear substantial relative to the sample while still being compatible with no difference and effects in either direction. The planning illustrations also show how target sample size changes when the assumed detectable effect becomes smaller or when the desired power increases. Those are planning principles, not evidence of the trial’s original design rationale.

Finally, the record lists secondary outcomes and safety counts but does not report analysis populations, missing-data methods, multiplicity handling, or detailed analyses. This demonstrates why registry summaries are valuable but not a complete substitute for a fully reported statistical analysis. The study’s posted results can be described transparently, while the limits of the available information remain explicit.

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.

The primary outcome groups are small: 12 participants for AH8 and 11 for placebo. The registry lists 24 participants enrolled, but the reason the primary-outcome group counts do not account for all enrolled participants is not reported. This makes it difficult to determine from the record whether the difference reflects missing outcome data, exclusions, or another reason.

The outcome uses time until return to baseline, but the registry does not report how observations were handled if a participant did not return to baseline within follow-up. It also does not describe the method for determining the return time, the treatment of incomplete visits, or any assumptions used in the analysis. These details are particularly relevant to interpreting a time-based outcome summarized by a mean.

Observed variability differs between the primary-outcome groups, with standard deviations of 1.48 months and 0.23 months. The record does not provide individual observations or an alternative analysis to show whether the estimated mean difference is sensitive to that difference in spread. Nor does it report baseline group summaries, covariate adjustment, sensitivity analyses, or a detailed statistical model.

The record does not report the original sample-size justification, analysis populations, multiplicity plan, missing-data procedures, or interim-analysis plan. It also does not report which roles were masked or give detailed visit timing after the one-month return described in the summary. Safety event terms and deaths are not reported in the registry record. These omissions limit assessment of the analysis process and completeness, but they do not by themselves show that any particular procedure was or was not used.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: A Study of Acetyl Hexapeptide-8 (AH8) in Treatment of Blepharospasm — NCT00942851.
• Registry record last updated 2012-09-06; status last verified 2012-08.
• Results first posted 2012-09-06.
• 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

This completed randomized, triple-masked, parallel phase 1/2 study compared AH8-containing topical cream with cream without AH8 in people with blepharospasm receiving BoNT injections. The registry lists 24 enrolled participants. The primary outcome was time until the JBRS returned to baseline, with posted outcome groups of 12 for AH8 and 11 for placebo.

The primary means were 3.71 months for AH8 and 3.03 months for placebo. The posted unadjusted mean difference was 0.68 months, with a confidence interval that includes zero and an unadjusted p-value of 0.116. The two secondary comparisons also have intervals that include zero. Safety summaries report no serious adverse events among 12 participants at risk in either group and two other adverse events in each group.

The registry does not report the original sample-size justification, analysis populations, missing-data or multiplicity methods, or detailed sponsor analyses. The posted estimates are therefore best read as uncertain summaries of a small trial, rather than definitive evidence about the size or direction of a group difference.