An Open-label Study of Poly-l-lactic Acid for Correction of Wrinkles in the décolletage Area: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for An Open-label Study of Poly-l-lactic Acid for Correction of Wrinkles in the décolletage Area (NCT05538728), a randomized na study. The primary outcome is Percentage of Responders on the Galderma Décolletage Scale (GDS), as Assessed Live by the Treating Investigator, at Month 9.

2. Clinical Question

3. Trial Design

This was a prospective, randomized, parallel-arm, open-label study of two reconstitution volumes of poly-l-lactic acid for décolletage wrinkles. The registry lists the study phase as NA and its status as completed. Enrollment was 30 participants. Randomization assigned 16 participants to Sculptra 8 ml and 14 to Sculptra 17 ml. The record names Galderma R&D as sponsor and gives the intervention type as a device.

The comparison was between the current label dilution volume of 8 ml and a new dilution volume of 17 ml. Both arms concerned treatment of wrinkles in the décolletage area. Since masking was listed as none, participants and study personnel were not masked according to the registry description. The record does not report further details of the randomization procedure, allocation concealment, treatment administration, or investigator training.

The primary endpoint was the percentage of responders on the Galderma Décolletage Scale at month 9, assessed live by the treating investigator. A responder was defined as a participant with at least one grade of improvement from baseline. The registry also identifies a month 6 GDS responder outcome and participant- and investigator-assessed Global Aesthetic Improvement Scale outcomes at months 6 and 9. Numerical results are posted for the month 6 GDS outcome; numerical estimates for the GAIS outcomes are not reported in the registry record.

The primary population was described as intent to treat, including randomized participants analyzed according to assigned treatment. The record does not report the original design assumptions, the rationale for the enrollment target, or further operational details about follow-up and analysis.

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: A total of 30 participants were enrolled and treated in this study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent to treat (ITT) population Included all participants who were randomized and analyzed according to the treatment they were randomized based on the randomization scheme.

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: Intent to treat (ITT) population Included all participants who were randomized and analyzed according to the treatment they were randomized based on the randomization scheme.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Responders on the Galderma Décolletage Scale (GDS), as Assessed Live by the Treating Investigator, at Month 9, measured over At Month 9.

The primary endpoint is the percentage of participants who were responders on the Galderma Décolletage Scale at month 9, based on a live assessment by the treating investigator. Response means at least one grade of improvement from baseline. The scale is described as a validated five-point measure of décolletage lines and wrinkles, ranging from Grade 0, none to minimal, through Grade 4, very severe. Higher scores indicate more severe lines and wrinkles.

A responder percentage turns each participant's change into a yes-or-no outcome: the participant either met the stated improvement threshold or did not. The endpoint therefore communicates how common this defined response was in each randomized arm. It does not describe the size of improvement among responders, distinguish a one-grade improvement from a larger one, or show the full distribution of scale scores. The registry does not report a separate threshold for what would count as a clinically important between-arm difference.

Using a defined responder criterion can make an outcome easier to interpret as the proportion meeting a specified improvement target. It also discards some detail from the underlying ordinal scale. The results should therefore be read as responder proportions under this particular definition, not as a complete account of every participant's change in décolletage severity.

7. Results Posted in the Registry

• Sculptra 17ml: 78.6% (11/14) versus 93.8% (15/16) on control; risk difference -15.2 percentage points (95% CI -39.7 to 9.4), risk ratio 0.84 (0.62–1.13); unadjusted two-proportion z-test p = 0.222.

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 Responders on the Galderma Décolletage Scale, as Assessed Live by the Treating Investigator, at Month 6

• 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:
  • Sculptra 17ml: 100.0% (12/12) versus 93.3% (14/15) on control; risk difference 6.7 percentage points (95% CI -6.0 to 19.3), risk ratio 1.07 (0.94–1.23); unadjusted two-proportion z-test p = 0.362.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sculptra 17ml and the control. The interval gives the range of effects that remain compatible with the data.

The registry identifies three secondary outcomes: the month 6 investigator-assessed GDS responder percentage, and participant- and investigator-assessed GAIS responder percentages at months 6 and 9. Numerical estimates are posted for the month 6 GDS outcome. The GAIS outcomes are listed, but their numerical results are not reported in the registry record.

The available month 6 GDS estimates show high responder percentages in both arms, with the posted percentage higher in the 17 ml arm at that time point. The associated risk-difference interval includes zero, and the unadjusted p-value is 0.362. This is a secondary result at an earlier assessment time; it neither replaces the month 9 primary endpoint nor resolves the uncertainty in the primary comparison. It also should not be treated as a separate, definitive replication of the primary result.

Secondary outcomes can add context by examining response at another time and by using participant or investigator global assessments. However, several outcomes and time points create multiple opportunities to observe patterns that may arise by chance. The registry does not report a multiplicity adjustment or a hierarchy governing how secondary outcomes should be interpreted. Unadjusted secondary comparisons therefore carry less evidential weight than a prespecified primary analysis, and any isolated pattern should be considered exploratory rather than conclusive.

The month 6 GDS assessment includes fewer participants than were randomized to each arm. The record does not explain why these counts differ or describe how missing observations were handled. This affects interpretation because the analyzed participants at that time may not represent all randomized participants if outcome availability is related to response or other factors. The registry's listed GAIS outcomes could offer additional perspectives, but without posted numerical results they cannot be used to corroborate or qualify the observed GDS pattern.

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

• Percentage of Responders on the Galderma Décolletage Scale, as Assessed Live by the Treating Investigator, at Month 6
• Percentage of Responders Who Achieved At Least "Improved" on the Global Aesthetic Improvement Scale (GAIS) as Assessed by Participant at Months 6 and 9
• Percentage of Responders With At Least "Improved" on the Global Aesthetic Improvement Scale (GAIS) as Assessed by Treating Investigator at Months 6 and 9

9. Statistical Interpretation

10. Statistical Methods Explained

The endpoint is binary at the participant level: each participant either meets the responder definition or does not. The reported percentage is the proportion of assessed participants who met that definition. The primary responder definition is at least one grade of improvement from baseline on the GDS. The scale itself has five ordered grades, but the primary analysis reduces the scale change to a responder status rather than comparing the complete distribution of grades.

What does the risk difference express?

A risk difference compares two proportions by subtracting one arm's event proportion from the other. Here, the posted comparison is for Sculptra 17 ml relative to Sculptra 8 ml. A negative estimate means the observed responder proportion was lower in the 17 ml arm; a value of zero corresponds to equal proportions. The estimate is -0.152, and its 95% confidence interval ranges from -0.397 to 0.094. Because that interval includes zero, the data do not precisely establish the direction of the underlying difference. The interval is wide, which is consistent with substantial uncertainty in a study with 16 and 14 randomized participants.

The registry also posts risk-ratio and odds-ratio intervals for the primary comparison. These are alternative ways of describing a contrast between binary outcomes. A risk ratio compares proportions as a ratio, while an odds ratio compares the odds of response. They answer related but differently scaled questions, and their numerical values should not be interchanged with the risk difference. The posted risk-ratio interval is 0.62 to 1.133; the posted odds-ratio interval is 0.022 to 2.676. Both intervals include the value corresponding to no relative association. The risk difference is often the most direct scale for describing an absolute difference in responder proportions, but none of these measures removes the uncertainty created by the small groups.

How should the p-value be read?

The primary comparison has an unadjusted p-value of 0.222. A p-value describes how unusual data at least as discordant with a specified null hypothesis would be under that hypothesis and the test's assumptions. It is not the probability that the null hypothesis is true, nor is it a measure of the size or importance of an effect. An unadjusted value does not account for testing multiple endpoints or time points. The registry record does not report the full statistical analysis plan or the particular method used to produce the posted confidence intervals and p-value. The value should therefore be read as the posted unadjusted comparison, not as a complete account of all possible analysis choices.

Why report confidence intervals?

A confidence interval gives a range of values compatible with the data under the method used to calculate it. Repeated use of a method with the stated coverage property would produce intervals containing the underlying parameter at the corresponding rate. It does not mean that there is a 95% probability that this particular fixed interval contains the true value. For a responder proportion, the interval communicates uncertainty about the population response percentage; for a risk difference, it communicates uncertainty about the contrast between arms. The registry specifies 95% confidence intervals but does not report the calculation method.

With binary outcomes, the amount of information depends in part on how many participants contribute usable observations and how responses are distributed. Small samples can yield broad intervals, even when observed percentages are high. A displayed percentage should not be read as precise merely because it is expressed to one decimal place. Precision is conveyed more meaningfully by the interval and the number of participants behind the estimate.

What is over-dispersion, in general?

In general, over-dispersion means that observed variation is greater than a statistical model assumes. If a model understates variation, standard errors may be too small and intervals or tests may appear more certain than warranted. This is a general statistical concept, not a reported feature of this trial. The registry record does not report a model-based analysis of over-dispersion, and the posted binary results should not be described as having been adjusted for it.

The primary population is specified as intent to treat, with participants analyzed according to randomized assignment. This preserves the assigned-group comparison in the stated analysis population. The month 9 arm counts match the randomized group sizes, but the record does not describe how missing outcomes, if any, were handled. The secondary month 6 counts differ from the randomized group sizes; reasons and missing-data procedures are not reported. That distinction matters because an analysis based on fewer observed participants can be affected by who did not contribute an outcome.

In general, randomized allocation is intended to make assigned groups comparable at baseline, while masking can reduce some assessment and behavior-related influences. This study was randomized but had no masking. That matters particularly for a live investigator assessment. The registry does not report procedures designed to mitigate possible assessment bias. These design considerations qualify interpretation but do not change the arithmetic description of the posted estimates.

11. Confidence Intervals and Precision

The month 9 estimates are accompanied by broad 95% confidence intervals. For Sculptra 8 ml, the reported responder percentage is 93.8%, with an interval from 69.8% to 99.8%. For Sculptra 17 ml, it is 78.6%, with an interval from 49.2% to 95.3%. Although both observed percentages are high, the intervals span a wide range of possible underlying response percentages. The study therefore provides limited precision about the response rate that might be expected beyond these participants.

The risk-difference interval is also wide: -0.397 to 0.094, around a posted estimate of -0.152 for the 17 ml arm relative to the 8 ml arm. It includes zero and allows values in both directions. Thus, the observed contrast is not estimated precisely enough to rule out either no difference or differences favoring either arm. The study does not establish equivalence: an interval that crosses zero is not, by itself, evidence that any difference is small enough to be unimportant. The registry does not report an equivalence margin or a clinical-importance threshold.

Confidence intervals reflect sampling uncertainty under the method used, not every source of uncertainty. They do not account automatically for possible bias from an open-label design, outcome measurement choices, missing-data assumptions, or selective reporting. The record does not specify the interval calculation method or describe missing-data handling. The numeric precision of an estimate should therefore be distinguished from the broader certainty of the evidence. With only 16 and 14 participants in the primary analysis, additional information would be needed for more precise estimates.

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 effect, not the trial's original enrollment rationale. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set at the stated fraction of the observed effect. The registry record does not report the assumptions used for the original trial design or its enrollment target.

For this binary outcome, the planning entries are participants per arm, not total events. The 80% power column gives the estimated number of participants in each arm for a design with an 80% chance of detecting the specified effect under the stated assumptions, if that effect and those assumptions were correct. The 90% power column gives the corresponding per-arm planning number for a 90% chance. These are design probabilities under assumptions, not probabilities that the observed study result is correct.

The entries include planning for 100% of the observed effect, planning for 75% of the observed effect, and planning for 50% of the observed effect. The smaller the effect a future study aims to detect, the more participants it generally needs, because a smaller contrast is harder to distinguish from random variation. The posted illustrations show that pattern, with larger per-arm requirements for the smaller fractions of the observed effect.

These figures are not observed power. They are planning illustrations calculated from this study's observed contrast and the listed assumptions. Because the observed effect is uncertain, particularly in a small study, planning based directly on it may not reflect the effect a future study should target. The record does not provide a separate clinically meaningful target 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 = 0.938; treatment proportion p₁ = 0.786; average p̄ = 0.862.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.4883 = 0.9571.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.4764 = 0.4010.
4. n = (0.9571 + 0.4010)² / (-0.1518)² = 80.1, rounded up to 81 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 <- 0.9375                          # control proportion
p1 <- 0.785714285714286                          # 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(5538728)
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 = 81 (80% power), 107 (90% power)
 75% of observed effect: n per arm = 127 (80% power), 169 (90% power)
 50% of observed effect: n per arm = 246 (80% power), 328 (90% power)
power.prop.test: 80.1 
Simulated power at n = 81 per arm: 0.818 (20000 replicates)

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

14. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and several secondary outcome measures across different assessment times and assessors. When multiple outcomes are examined, the chance of at least one apparently notable result can increase. Statistical approaches can address this issue by adjusting significance thresholds, defining an ordered testing strategy, or distinguishing confirmatory from exploratory outcomes. The registry record does not report whether any such multiplicity strategy was planned or used. The posted comparison p-values are unadjusted, so they should not be interpreted as controlling the overall error rate across the outcome family.

The record describes the primary analysis population as intent to treat, including randomized participants analyzed according to assigned treatment. The month 9 primary outcome counts are 16 and 14, the same as the randomized group sizes. The month 6 GDS counts are 15 and 12. The registry does not report reasons for the differing month 6 counts, whether these participants lacked assessments, or what procedures were used to address missing data. It also does not state whether any imputation, sensitivity analysis, or other missing-data method was used.

Missing outcome data can matter if the likelihood of having an assessment is related to a participant's response or other characteristics. An analysis restricted to observed assessments may differ from the result that would have been obtained if all randomized participants had complete outcome information. This is a general concern, not evidence that the month 6 result is biased. The available record does not permit evaluation of the direction or size of any such effect.

The record does not report an interim analysis plan, stopping rule, full statistical analysis plan, or details of the confidence-interval calculation. It also does not report a sample-size justification for the original design. These omissions limit assessment of how the posted analyses relate to planned procedures. They do not negate the descriptive estimates, but they constrain conclusions about confirmatory interpretation, multiplicity, and robustness.

15. 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 zero serious adverse events among 16 participants in the Sculptra 8 ml arm and zero among 14 participants in the Sculptra 17 ml arm. It also reports zero deaths in each arm. These counts mean that no events in those categories were posted for the study groups; they do not establish that the risk of a serious event is absent.

Other adverse events affected 5 participants in the 8 ml arm and 4 participants in the 17 ml arm. These are counts of participants affected, not event rates adjusted for exposure time. The registry record does not provide event terms, severity, timing, duration, or a comparison analysis for these other events. No top serious adverse-event terms are listed.

Safety interpretation is limited by the small number of participants and the absence of detail about the events. The counts are descriptive observations from this study and should not be used alone to make a broad comparative safety conclusion between the reconstitution volumes.

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

The posted results describe responder proportions at the specified assessment times in a randomized, open-label study of two Sculptra reconstitution volumes. At month 9, the observed responder percentage was higher in the 8 ml arm than in the 17 ml arm, while the risk-difference interval includes zero and is broad. This means the comparison remains uncertain: the data do not precisely identify the direction or size of the underlying difference.

The finding does not establish that the two volumes are equivalent. Equivalence requires a prespecified margin defining differences small enough to be considered practically unimportant, together with an analysis designed to assess that margin. No such margin is reported. Likewise, a non-significant unadjusted p-value does not establish that there is no difference. It indicates that the posted test did not give strong evidence against its null hypothesis under the analysis used.

The endpoint captures whether a participant improved by at least one GDS grade, not how much every participant changed or whether the change mattered to them. The registry does not report a threshold for clinical importance. The live investigator assessment was conducted in an open-label study, so the posted response percentages should be considered in light of the absence of masking. The record also does not provide enough detail to assess potential missing-data effects or the full multiplicity strategy.

The safety record shows no reported serious adverse events or deaths, and it records other adverse events in both arms. Given the small groups and limited event detail, these observations cannot determine the comparative safety profile with precision. The results are informative as a record of what was observed in this completed study, but they do not, alone, settle comparative efficacy, clinical importance, or safety.

17. Why This Trial Matters Statistically

This study illustrates how a randomized comparison can still produce substantial uncertainty when the groups are small. The primary responder percentages are high, but the confidence intervals extend across broad ranges, and the risk-difference interval includes zero. Looking at the estimate together with its interval is more informative than treating the observed percentages or a p-value as a complete answer.

It also demonstrates the importance of distinguishing a responder endpoint from the underlying scale. The GDS is an ordered five-point assessment, while the primary outcome classifies participants according to whether they achieved at least one grade of improvement. That threshold makes the result readily interpretable as a percentage, but it does not describe the magnitude or distribution of individual changes.

The study is randomized, yet open-label, and the primary endpoint was assessed live by the treating investigator. Statistical interpretation therefore requires attention to both sampling uncertainty and design features that can affect measurement. The secondary outcome pattern, differing assessment counts, and lack of reported multiplicity and missing-data procedures further show why a single numerical comparison should not be separated from its analysis context.

Finally, planning calculations based on an observed effect can help illustrate how sample requirements change as target effects become smaller. They are not a substitute for a design rationale based on a meaningful target effect and the intended analysis. The registry record does not report that original rationale. These statistical distinctions help readers understand what the posted results can support and where uncertainty remains.

18. Limitations

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

The study enrolled 30 participants, with 16 randomized to Sculptra 8 ml and 14 to Sculptra 17 ml. These small groups produce limited precision, as reflected in the broad confidence intervals for the primary percentages and contrast. Estimates may be sensitive to the outcomes of a small number of participants.

The study was open-label, with no masking, and the primary endpoint was assessed live by the treating investigator. The registry does not report masking of outcome assessors or other safeguards against possible assessment influences. The endpoint is based on a one-grade responder threshold, so it does not show the full range of change on the GDS or provide a reported measure of clinical importance.

The month 6 GDS results include fewer participants than were randomized, and the reasons and missing-data approach are not reported. Numerical results for the listed GAIS secondary outcomes are not reported in the registry record. The record also does not report a multiplicity plan, the method used to calculate confidence intervals, the original sample-size justification, or the full statistical analysis plan.

These limitations do not invalidate the posted observations, but they constrain precision and interpretation. In particular, the available record cannot establish equivalence, determine the clinical importance of the contrast, or fully assess how missing data and multiple outcomes may affect the conclusions.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: An Open-label Study of Poly-l-lactic Acid for Correction of Wrinkles in the décolletage Area — NCT05538728.
• Registry record last updated 2024-08-20; status last verified 2024-07.
• Results first posted 2024-08-20.
• 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.

22. Record Summary

NCT05538728 is a completed prospective, randomized, parallel-arm, open-label study of Sculptra reconstitution volumes for décolletage wrinkles. It enrolled 30 participants: 16 in the 8 ml arm and 14 in the 17 ml arm. The primary outcome was the month 9 percentage with at least one grade of improvement on the investigator-assessed Galderma Décolletage Scale.

The month 9 responder percentages were 93.8% for 8 ml and 78.6% for 17 ml. The posted risk difference for 17 ml relative to 8 ml was -0.152, with a 95% confidence interval from -0.397 to 0.094 and an unadjusted p-value of 0.222. The interval indicates substantial uncertainty about the between-arm contrast.

The record reports zero serious adverse events and zero deaths in both arms, with other adverse events affecting 5 participants in the 8 ml arm and 4 in the 17 ml arm. Several analysis details, including missing-data procedures, multiplicity handling, and the original design assumptions, are not reported in the registry record.