Post Market Study Evaluating Princess Filler Lidocaine for the Correction of Nasolabial Folds: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Post Market Study Evaluating Princess Filler Lidocaine for the Correction of Nasolabial Folds (NCT03611491), a na na study. The primary outcome is Change From Baseline in Average Nasolabial Folds-Severity Rating Scale (NLF-SRS) Grade Based on Investigator Assessment at Week 24.

2. Clinical Question

In general, a single-group study can document outcomes over time in people receiving an intervention. A change from baseline can describe whether ratings at follow-up differ from initial ratings, but without a concurrent comparator it cannot separate an intervention-associated change from other explanations, such as natural fluctuation, expectations, or the way measurements are made. Those are general interpretive considerations, not findings about what happened to participants in this study.

3. Trial Design

The registry describes a prospective, open-label, multicenter, post-market study. It is marked completed, with a recorded enrollment of 60. The intervention is Princess® FILLER Lidocaine, classified in the record as a device. The study has a single group; allocation is listed as not applicable, and masking is listed as none. These design features mean the registry does not describe random assignment or a masked comparison between groups.

The brief description says that eligible subjects with moderate to severe nasolabial folds would receive treatment and return for follow-up assessments at Weeks 2, 4, 24 and 36. A touch-up at Week 2 could be given if the investigator deemed it appropriate. The arm description specifies injections up to 10 ml at baseline. The primary outcome is assessed at Week 24 after the initial treatment. The registry record does not state how many participants received a touch-up or how that treatment was handled in the primary analysis.

The study dates recorded are 2017-09-20 for start and 2018-11-19 for primary completion. The record does not describe a control condition, a comparison against another intervention, or a treatment assignment procedure. It also does not report a protocol-level statistical analysis plan or sample-size justification. The planning illustration assumptions recorded separately describe equal allocation between two hypothetical arms, whereas the actual study is single-group. Such an illustration should not be mistaken for the study's design or for evidence that the trial was powered for a particular comparison.

In general, prospective follow-up means outcomes are planned for collection after enrollment rather than assembled solely from existing records. Open-label status means masking is not part of the recorded design; it does not, by itself, establish the direction or size of any measurement effect. In an investigator-rated outcome, the absence of masking is relevant context because ratings can involve judgment. The registry record does not describe steps used to standardize or independently verify the primary investigator assessment.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The population used consists of all participants who received the investigational device and had at least one post-treatment assessment (e.g., first pain assessment after injection). Only subjects with available data for week 24 were included in the analysis.

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 Change From Baseline in Average Nasolabial Folds-Severity Rating Scale (NLF-SRS) Grade Based on Investigator Assessment at Week 24, measured over Baseline and Week 24.

The primary endpoint is change from baseline in the average Nasolabial Folds-Severity Rating Scale grade, based on investigator assessment at Week 24. The two sides of the face were graded separately on the five-point scale, and the average of the left and right grades was used for analysis. The scale categories are 0 (None/minimal), 1 (Mild), 2 (Moderate), 3 (Severe) and 4 (Extreme). The endpoint therefore summarizes investigator-rated fold severity across both sides rather than reporting each side as a separate primary outcome.

Change over time is used to describe how a measured outcome at follow-up differs from its baseline value. In general, baseline measurement gives a reference for interpreting a later score, while averaging the two sides provides one participant-level summary for analysis. Because the underlying ratings are ordered categories, the numerical spacing between adjacent categories should not automatically be taken to represent an equal clinical difference. Averaging left and right grades can also yield a summary that is not itself one of the original category labels.

The registry identifies the primary measure as a mean and its dispersion as a standard error. However, the numerical mean change and standard error are not reported in the registry record. The record also does not specify whether change is calculated as Week 24 minus baseline or baseline minus Week 24. Without the estimate and its direction convention, the endpoint's observed size and direction cannot be interpreted from the registry record. The rationale for selecting Week 24 as the primary time point is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a mean change in a continuous summary measure. The underlying Nasolabial Folds-Severity Rating Scale consists of ordered grades from 0 (None/minimal) to 4 (Extreme). The registry says that the two sides were assessed separately and averaged for analysis. This produces one summary per participant for the endpoint, followed by a group-level mean change. The record does not give the numerical mean change, so the statistical quantity is specified but its observed value is unavailable.

What does a mean change describe?

In general, a mean change describes the average within-participant difference between measurements at two time points. It is distinct from a comparison of two unrelated group means because each participant's follow-up value is considered in relation to that participant's baseline. This can account for the pairing of measurements in the analysis, provided the participants contributing to the estimate have the required measurements. The registry states that only subjects with available Week 24 data were included in the primary analysis. It does not report the number included or the specific calculation convention for the difference.

For an ordered scale, numerical coding allows averages and changes to be calculated, but the mean relies on treating the coded grades as suitable for arithmetic summaries. In general, an average can be useful for describing the center of a group, while it may conceal the distribution of individual changes. A mean alone does not show how many participants improved, remained unchanged, or worsened. The registry lists a threshold-based secondary outcome of at least one-point reduction, but its result is not reported in the registry record. The primary mean change and the threshold outcome answer different questions and should not be treated as interchangeable.

What does the standard error communicate?

The registry identifies standard error as the dispersion measure for the primary endpoint. In general, a standard error describes the sampling uncertainty of an estimated mean under a statistical model; it is not a description of the spread of individual participant scores. A standard deviation, by contrast, describes variation among individual observations. The record does not report the standard error's value, so the precision of the estimated mean cannot be judged. No confidence interval is reported either. A confidence interval is generally used to show a range of plausible values for an underlying effect under the model and assumptions, but it cannot be reconstructed from the information without performing a new calculation, which is not appropriate for interpreting an absent result.

The primary analysis population is described as all participants who received the investigational device and had at least one post-treatment assessment, with only subjects having available Week 24 data included in the analysis. This definition is not the same as a statement that every enrolled participant contributed to the primary endpoint. In general, an analysis restricted to people with observed follow-up data may be affected if availability is related to outcomes or participant characteristics. The registry does not report the amount or pattern of missing Week 24 data, reasons for missingness, or any method used to address missing observations.

Why does the design affect interpretation?

This is a single-group study without a comparator. In general, a within-group change can be estimated without a control group, but it does not isolate a causal effect. A control group would help indicate how outcomes might change over the same period absent the intervention or under another treatment. Since the record describes no such group, comparisons to an external benchmark would require additional assumptions and are not reported as part of the study results. The record also lists no masking. With an investigator-rated endpoint, lack of masking is relevant context for potential assessment bias, although the record does not establish that bias occurred.

The registry's planning assumptions mention a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation for an illustration based on the observed effect. These are assumptions for planning illustrations, not evidence of the trial's own design or an observed probability of detecting an effect. Equal allocation between two arms does not match the recorded single-group study. Any sample-size illustration based on an observed effect is a hypothetical planning exercise and should not be read as observed power. The trial's own sample-size justification and statistical plan are not reported in the registry record.

In general, normal-approximation methods rely on the distribution of the estimator being adequately represented by a normal model for the intended inference. The registry does not describe diagnostic checks, robust methods, or alternative analysis methods for the primary outcome. Because the numerical result is absent, it is also not possible to evaluate the observed distribution or the influence of unusual values. No adjustment factors, covariates, or subgroup analyses are described in the record.

Repeated assessments are recorded at multiple follow-up times, and several secondary outcomes are listed. In general, multiple outcomes and time points create opportunities for selective emphasis and increase the chance of at least one apparently unusual finding when many tests are conducted. Whether and how multiplicity was addressed is not reported in the registry record. The record lists zero analysis entries, so it does not provide inferential results with which to assess test selection or multiplicity procedures.

Interpretation would normally consider the estimate, its uncertainty, the outcome scale, missing data, analysis population, and design together. Here, the scale and population definition are described, but the estimate and uncertainty are not. Statistical methods can explain what a reported mean, standard error, confidence interval, or p value would mean in general; they cannot supply a result that the registry does not report. No recalculated estimate is presented because the necessary primary outcome summary statistics are not reported.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Princess® FILLER Lidocaine")
n   <- c(59)
m   <- c(-1.8)
sp  <- c(0.6)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Princess® FILLER Lidocaine  59  -1.800  4.609  -3.001  -0.599

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome at Week 24 and several secondary outcomes at other time points. These include severity-scale change, a threshold reduction in severity grade, investigator-assessed aesthetic improvement, subject satisfaction, pain intensity, and independent reviewer assessment of photographs. Considering multiple outcomes and time points can raise multiplicity concerns. In general, if many statistical tests are performed, the chance of at least one apparently notable result can increase. A prespecified testing hierarchy or adjustment can address some multiplicity concerns, but the registry record does not report a multiplicity strategy.

The record lists zero analysis entries. It does not report p values, confidence intervals, or numerical results for the primary or secondary outcomes. Therefore, it is not possible to determine which analyses were performed, how many tests were conducted, whether any adjustment was used, or how findings were selected for emphasis. The registry's outcome descriptions do not establish that all listed outcomes were analyzed or that no other analyses were performed.

For the primary outcome, the analysis population includes participants who received the device and had at least one post-treatment assessment, with only those having available Week 24 data included. The number with available Week 24 data, reasons for unavailable data, and methods for handling missing observations are not reported in the registry record. In general, missing data can affect an estimate if the probability of an observation being missing is related to the outcome or other participant characteristics. The direction and size of any such effect cannot be inferred without further information.

The record also does not report whether sensitivity analyses were conducted to examine the effect of different assumptions about missing data. It does not describe whether analyses included all enrolled participants, all treated participants, or another defined population beyond the stated primary analysis population. These omissions limit assessment of robustness and of how closely the analyzed participants correspond to the enrolled group.

12. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: haematoma infection (1.7%), papillary thyroid cancer (1.7%).

The registry records safety counts for the Princess® FILLER Lidocaine group. It lists 2 participants affected by serious adverse events among 60 at risk for that category, 27 participants affected by other adverse events among 60 at risk for that category, and 0 deaths. These are registry counts, not estimates from a comparison between groups. The record lists Haematoma infection and Papillary thyroid cancer among the serious adverse-event terms, each with a recorded percentage of 1.7%.

In general, an adverse-event count describes events or participants meeting the registry's reporting category; it does not by itself establish a causal relationship to the intervention. The registry record does not provide a control group or comparative risk estimate. It also does not report enough detail to determine event timing, severity beyond the serious-event classification, outcomes, or whether investigators considered the events related to the device. The serious-event terms should therefore be read as reported safety information, not as proof of causation.

The serious and other adverse-event categories are separately reported. They should not be added together to infer a total number of affected participants, since the record does not state whether participants could appear in both categories. Likewise, the percentage attached to each serious-event term should be read as recorded; the registry does not provide further explanation of its calculation in this entry.

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

The study addresses a defined measurement question: how investigator-rated nasolabial-fold severity changed from baseline to Week 24 among participants with available data. It specifies the scale, the two-sided assessment, and the use of an average score. This information makes the endpoint understandable as a planned measure. However, the mean change and its uncertainty are not reported in the registry record, so the record does not show the amount or precision of the observed change.

The study is single-group and open-label, with no comparator and no masking recorded. Consequently, even if a before-and-after estimate were available, it would describe change over time in the studied participants rather than establish how outcomes differed from what would have occurred under another condition. In general, a comparison group can help distinguish intervention-associated change from other influences, while masking can reduce some opportunities for expectations to affect assessment. Neither feature is described for this study.

The registry also lists secondary outcomes spanning investigator ratings, subject assessments, and independent review of photographs. Those measures could address complementary aspects of outcome, but their numerical results are not reported. The registry's safety counts provide descriptive event information, but there is no comparative safety estimate. The record does not establish whether the listed events were caused by the intervention.

These limits do not show that the intervention had no effect, nor do they show that it had an effect. They identify what the available registry information can support: a description of the design, outcome definitions, analysis population definition, and adverse-event counts. The primary endpoint's magnitude, precision, and direction cannot be judged without its numerical result and the convention used to define change. A claim of statistical significance, clinical importance, or causal effect would require evidence not reported in the registry record.

General statistical reasoning can clarify what measures such as a mean change, standard error, or confidence interval represent. It cannot replace missing results. Similarly, absence of an analysis entry is not proof that no analysis occurred; it means the registry record does not document inferential results for assessment. The appropriate interpretation is therefore limited and descriptive.

14. Why This Trial Matters Statistically

This study is statistically notable for the contrast between a clearly defined primary measurement and the absence of its numerical result in the registry record. The endpoint is described in enough detail to identify the rating scale, the sides included, the visit of interest, and the stated analysis population. Yet without the estimated mean change and a measure of uncertainty, readers cannot assess either the size of the finding or how precisely it was estimated.

The single-group design also illustrates an important distinction between change and treatment effect. A within-participant comparison over time may be a useful descriptive analysis, but it does not provide the same evidence as a controlled comparison. Open-label investigator ratings add another interpretive consideration because the primary measure involves assessment rather than an entirely objective event count. These features do not invalidate the measurement; they define the limits of what a result could establish.

Several outcome types and follow-up times are listed. In general, assessing multiple outcomes can offer a broader account of experience, but it also makes transparent reporting of the analysis plan and multiplicity approach important. Those methods are not reported in the registry record, and no numerical outcome results are available for evaluating consistency across measures.

The safety record provides descriptive counts but no comparator. It is therefore useful as a record of reported events, while not serving as a comparative estimate or establishing causality. Taken together, the trial is a reminder that interpretation depends not only on the endpoint definition but also on the result, its uncertainty, the comparison structure, and transparent reporting of missing-data and analysis methods. In this case, the design and measurement details can be described, while the primary efficacy estimate and inferential results cannot be assessed from the registry record.

15. 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 principal limitation for statistical interpretation is that the primary endpoint's numerical result is not reported in the registry record. The mean change and standard error are identified as the intended summary, but neither value is available, and no confidence interval or p value is reported. The scale's change convention is also not stated, so even the direction of a hypothetical estimate could not be interpreted from this entry alone.

The study is single-group, open-label, and has no masking recorded. There is no concurrent comparator for separating change over time from other influences, and the investigator-rated primary outcome may be susceptible in general to assessment effects when treatment status is known. The registry does not describe procedures intended to limit such effects or provide the primary numerical result for evaluating it.

The primary analysis includes only participants with available Week 24 data, but the number analyzed and the extent and reasons for missing follow-up are not reported. No missing-data method or sensitivity analysis is described. The record also does not report a statistical analysis plan, sample-size justification, or multiplicity procedure. It lists several secondary outcomes and time points, but their numerical results are absent. Accordingly, there is no basis in the registry record to assess robustness across outcomes, missing-data assumptions, or analytical choices.

The recorded safety counts have no comparison group and do not establish causal attribution. The registry information does not detail event timing, resolution, or relatedness. Finally, the planning illustration's assumptions describe a hypothetical equal-allocation, two-arm setting, not the recorded single-group design; it should not be interpreted as the study's own design or as observed power.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Post Market Study Evaluating Princess Filler Lidocaine for the Correction of Nasolabial Folds — NCT03611491.
• Registry record last updated 2025-03-18; status last verified 2018-01.
• Results first posted 2025-03-18.
• 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.

19. Record Summary

The registry describes NCT03611491, a completed, prospective, open-label, multicenter, post-market, single-group study of Princess® FILLER Lidocaine for correction of nasolabial folds. Recorded enrollment is 60. The primary outcome is investigator-assessed change in average Nasolabial Folds-Severity Rating Scale grade from baseline to Week 24, with left and right sides averaged. The primary analysis population is described as treated participants with at least one post-treatment assessment and available Week 24 data.

The registry record does not report the primary outcome estimate, standard error, confidence interval, or p value. It lists serious adverse events affecting 2 participants, other adverse events affecting 27 participants, and 0 deaths. Because the study has no comparator and does not report numerical efficacy results, the record supports design and outcome description but not a quantitative assessment of primary outcome change or a causal treatment effect.