Safety and Efficacy Study of Different Dose Levels of EXC 001 to Improve the Appearance of Scars in Subjects Undergoing Elective Abdominoplasty: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy Study of Different Dose Levels of EXC 001 to Improve the Appearance of Scars in Subjects Undergoing Elective Abdominoplasty (NCT01038297), a randomized phase 2 study. The primary outcome is Part B: Expert Panel Scar Assessment Score.

2. Clinical Question

The clinical focus is the appearance of incision scars after elective abdominoplasty, not a broad assessment of scar treatments across other procedures or populations. The study also evaluated safety, with posted adverse-event counts for Part A and Part B cohorts. The registry identifies the study as phase 2 and lists enrollment of 30. It describes the trial as randomized and double-blind. The record does not report detailed procedures for assigning treatment, maintaining blinding, or selecting the dose levels. The primary question is therefore best read as a comparison of paired scar scores within the reported Part B cohorts, with the limits of those recorded data in mind.

3. Trial Design

The registry describes NCT01038297 as a phase 2, randomized, double-blind, within-subject controlled, dose-ranging study of EXC 001 for incision scars in the pannus of people undergoing elective abdominoplasty. The study status is completed, and enrollment is listed as 30. The record identifies Pfizer as the sponsor. It lists a start date of 2009-12-01 and a primary completion date of 2010-07-07.

The study has Part A and Part B. The primary outcome is specifically a Part B outcome, evaluated at Week 13. In Part B, the listed dose levels are 5.0 mg/Linear cm and 1.0 mg/Linear cm. Participants' EXC 001-treated scar scores were compared with their placebo-treated scar scores, and the difference was calculated within participant. Thus, the principal comparison is not a simple comparison of unrelated groups of participants: it uses a pair of scar observations from the same participant.

Part B results are reported across three cohorts, with separate entries for high and low dose in each cohort. The registry lists eight participants for each of the two dose entries in Cohort 1, and ten for each dose entry in Cohorts 2 and 3. These outcome counts should not be confused with the overall enrollment. The primary analysis population was a completer population defined by missed doses, availability of the Week 13 assessment, and non-missing VAS data for at least one dose level.

The record names placebo as the comparator and lists EXC 001 and placebo as drug interventions. It does not report the allocation sequence, the mechanics of randomization, masking procedures, dose administration details, or the rationale for the cohort structure. Those features cannot be reconstructed from the posted record. The registry lists six secondary outcome measures, including a physician-observer scar assessment and safety measures such as vital signs, physical examination findings, ECG findings, laboratory findings, and skin sensitivity reactions. The record lists seven outcome measures in total. It does not report results for those secondary measures in the posted outcome results summarized for this 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: Part B (incision wounds \[IW\] and abdominoplasty surgery): On Day 1, participants received 20 incisions (2 centimeters \[cm\] each), 10 incisions on either side of the midline (4 vertical columns of 4 incisions each, 2 columns of 2 incisions \[lateral biomarker incisions\]), on the abdominal area to be removed during abdominoplasty.

Part A: Skin Testing Phase (50 Days)

Reasons for not completing this period:

Part B: Active Dosing Phase (13 Weeks)

Analysis population for the primary outcome, as defined in the registry: Completer population included all participants who missed not more than 1 dose of study drug, had the Week 13 assessment and non-missing data for VAS scar assessment score for at least one dose level.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Safety population included participants who completed Day 1 of Part A and received at least 1 dose of study drug.

6. Primary Endpoint

The registry lists the primary outcome as Part B: Expert Panel Scar Assessment Score, measured over Week 13 of Part B.

The primary endpoint is the Part B Expert Panel Scar Assessment Score at Week 13. Expert panel members assessed blinded photographs using a 100 millimeter visual analog scale. A score of 0 mm represents the best possible scar and a score of 100 mm the worst possible scar; higher scores indicate worse condition. The reported value is the within-participant average difference between the EXC 001-treated and placebo-treated scars.

The direction of the calculation matters: the registry defines the contrast as EXC 001 score minus placebo score. A negative difference therefore means the measured score was lower for the EXC 001-treated scar in that participant-level comparison; a positive difference means it was higher. This direction describes the numerical scale and does not, by itself, establish whether a difference is statistically reliable or clinically important.

A visual assessment endpoint is used to quantify scar appearance in a structured way rather than relying only on an unstructured description. Blinded photographic assessment is intended to separate score assignment from knowledge of treatment, although the record does not report the procedures used to achieve or assess masking. The paired, within-participant comparison also accounts for the design in which each participant contributed an EXC 001-treated scar and a placebo-treated scar. Interpretation still depends on the variability of those paired differences, the number of participants contributing data, and the completeness of the assessment.

The registry reports means and standard deviations for the within-participant differences in each cohort and dose entry. It does not report confidence intervals or inferential test results for this primary endpoint. Consequently, the posted summary supports a description of direction and variability, but not a definitive estimate of precision or statistical evidence from a test.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the reported mean represent?

The endpoint is continuous: each scar receives a score on a visual analog scale, and the primary result is a mean of within-participant differences. For each participant contributing data, the difference is defined as the EXC 001 score minus the placebo score. The reported cohort-and-dose mean summarizes those paired differences. It is not the mean score for EXC 001 alone, nor is it a comparison of two unrelated sets of participants.

Pairing is important because the two scars being compared belong to the same participant. Individual characteristics that affect both scars may be shared within that pair. The analysis focuses on the difference within participant, then summarizes those differences. This design feature does not guarantee that every source of variation is removed; it describes how the contrast is constructed.

How should the standard deviation be read?

The standard deviation describes how widely the observed paired differences vary around their mean. A larger standard deviation indicates more dispersion in the participant-level differences, while a smaller one indicates less dispersion. It does not quantify the uncertainty in the mean as directly as a confidence interval would. A standard deviation should therefore not be read as a margin of error, and it does not by itself show whether an observed mean is compatible with no average difference.

For continuous outcomes, variability matters because a mean can conceal a broad range of individual differences. General statistical interpretation: if observations are highly variable, a mean may be estimated less precisely unless the amount of information is sufficient. The registry reports standard deviations but does not report confidence intervals for these estimates, so the precision of each mean cannot be judged directly from an interval in the posted results.

What would a confidence interval add?

General statistical explanation: a confidence interval gives a range of values compatible with the data and the specified statistical method, while communicating uncertainty around an estimate. It is not a guarantee that the true value lies in the interval, and its interpretation depends on the method and assumptions used. For the primary endpoint, the registry record does not report confidence intervals. Their absence means the reader cannot use the posted results to assess interval width or whether an interval includes zero.

Likewise, no p-values or inferential test results are reported for the primary outcome. The registry results therefore provide descriptive estimates and spreads, not a reported test of a null hypothesis. A negative mean is not, on its own, evidence that the difference is statistically distinguishable from zero; nor does a positive mean establish a difference in the opposite direction. The pattern across cohorts and doses is descriptive, and no formal dose comparison is reported.

Why does the analysis population matter?

The primary outcome uses a completer population. The record defines it as participants who missed not more than 1 dose of study drug, had the Week 13 assessment, and had non-missing VAS scar-assessment data for at least one dose level. This definition means the analyzed participants are selected using adherence and outcome availability. It does not necessarily include every enrolled participant, and the registry does not provide a participant flow or a full account of missing primary-outcome observations.

In a within-subject design, a participant may have usable information for one dose level without usable information for another, as the inclusion criterion requires data for at least one dose level. The posted outcome counts differ by cohort and dose entry. The record does not explain the reasons for those differences or describe an imputation procedure. Readers should not assume that missing scores were treated as unchanged, that complete pairs were available for every participant, or that missingness had no effect.

What do the planning illustrations mean?

The planning illustrations use the observed effect as their starting point, with equal allocation, a two-sided significance level of 0.05, and a normal approximation. They consider a stated fraction of the observed effect. These are hypothetical planning calculations, not the trial's design justification and not observed power. A sample size calculated from an observed estimate is especially dependent on that estimate, which can be unstable when the observed groups are small. The registry record does not report the trial's own sample-size justification, and no planning illustration should be mistaken for evidence about the probability that this completed trial detected an effect.

General statistical explanation: over-dispersion means that variation is greater than a model expects. When variability is underestimated, estimated uncertainty can be too small and inferential conclusions can become overconfident. The registry reports standard deviations for the continuous paired differences, but does not report a model-based analysis, an over-dispersion assessment, or a sensitivity analysis. A normal approximation used for planning does not establish that the primary outcome analysis used a normal model.

Finally, the registry lists zero posted primary outcome analyses. That does not alter the descriptive values, but it means the record does not document a statistical analysis result such as an adjusted estimate, test, or confidence interval. The reported means should be interpreted within that narrow evidential scope.

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("Part B: Cohort 1: EXC 001 High Dose (5.0 mg/Linear", "Part B: Cohort 1: EXC 001 Low Dose (1.0 mg/Linear ", "Part B: Cohort 2: EXC 001 High Dose (5.0 mg/Linear", "Part B: Cohort 2: EXC 001 Low Dose (1.0 mg/Linear ", "Part B: Cohort 3: EXC 001 High Dose (5.0 mg/Linear", "Part B: Cohort 3: EXC 001 Low Dose (1.0 mg/Linear ")
n   <- c(8, 8, 10, 10, 10, 10)
m   <- c(-3.16, 0.18, 1.45, 2.91, -4.78, -4.05)
sp  <- c(7.687, 7.154, 12.45, 9.778, 11.326, 8.934)
sd  <- sp      # posted standard deviations
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  Part B: Cohort 1: EXC 001 High Dose (5.0 mg/Linear  8  -3.160  7.687  -9.586  3.266
CARM  Part B: Cohort 1: EXC 001 Low Dose (1.0 mg/Linear   8  0.180  7.154  -5.801  6.161
CARM  Part B: Cohort 2: EXC 001 High Dose (5.0 mg/Linear  10  1.450  12.450  -7.456  10.356
CARM  Part B: Cohort 2: EXC 001 Low Dose (1.0 mg/Linear   10  2.910  9.778  -4.085  9.905
CARM  Part B: Cohort 3: EXC 001 High Dose (5.0 mg/Linear  10  -4.780  11.326  -12.882  3.322
CARM  Part B: Cohort 3: EXC 001 Low Dose (1.0 mg/Linear   10  -4.050  8.934  -10.441  2.341

11. Multiplicity, Missing Data and Analysis Populations

The study lists a primary scar-assessment outcome and six secondary outcome measures. The secondary list includes physician-observer scar assessment, safety-related changes in vital signs, physical examination, ECG findings and laboratory results, and skin sensitivity reactions. Considering multiple outcomes or multiple dose-and-cohort comparisons can raise a multiplicity issue: the more comparisons made, the greater the chance of at least one apparently unusual result arising by chance when all comparisons are considered together. General statistical explanation: prespecified testing strategies or adjustment methods can address some multiplicity concerns, but their use cannot be assumed.

The registry record does not report a multiplicity adjustment, a hierarchy for testing outcomes, or a prespecified testing strategy for the several cohort and dose entries. It also does not report inferential test results for the primary endpoint. Consequently, the posted means are not evidence that multiplicity was controlled, and no formal claim across the set of comparisons can be reconstructed.

The primary outcome population includes participants who missed not more than 1 dose, had the Week 13 assessment, and had non-missing VAS data for at least one dose level. The record does not report the number excluded from this population, the reasons for missing assessments, how missing scores were handled, or whether sensitivity analyses were performed. It does not state whether analyses were conducted by intention to treat. The primary outcome counts are therefore best understood as the counts listed for the reported completer results, not as a full accounting of every randomized participant.

Missingness can affect a result if participants with unavailable assessments differ systematically from those with observed assessments. General statistical explanation: complete-case or completer analyses describe those with usable data under the specified inclusion criteria; they may not represent all randomized participants if missingness is related to outcome or treatment. The record does not give enough information to determine whether that concern applies in this trial. It also does not report interim analyses, a statistical analysis plan, or further detail on analysis populations.

12. 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 lists serious adverse event counts of 0 in each reported Part A and Part B group. The corresponding numbers at risk are 10 for each Part A cohort, 9 for Part B Cohort 1, and 10 for each of Part B Cohorts 2 and 3. These are the posted group-level counts; they are not estimates of comparative risk between EXC 001 and placebo. Part B groups are described as receiving EXC 001 and placebo, but the adverse-event entries do not separate events by the treated scar or assign events to one product rather than the other.

Other adverse events are listed for 2 participants in Part A Cohort 1, 2 in Part A Cohort 2, and 1 in Part A Cohort 3. In Part B, the listed counts are 9 in Cohort 1, 8 in Cohort 2, and 8 in Cohort 3. These are counts of participants with other adverse events, not a measure of severity or a causal attribution. The record does not provide detailed event terms in the listed safety summary.

The death counts are not reported in the registry record. The absence of listed serious events should not be expanded into a claim about unreported outcomes, nor does a count of zero prove that a risk is absent. The groups are small, and the registry record does not provide a controlled, event-specific safety comparison or detailed exposure information. These figures are a limited description of events recorded for the listed groups, not a complete safety assessment.

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

The primary results describe average Week 13 differences in expert-panel scar scores between EXC 001-treated and placebo-treated scars within participants. The differences are reported separately for each cohort and dose. Their signs are not uniform: some means are negative and some are positive under the registry's EXC 001-minus-placebo convention. This description is confined to the posted outcome values and does not imply a general conclusion about efficacy.

The spread around the reported means and the small cohort-specific counts are relevant to how cautiously the values should be read. The registry does not report confidence intervals, p-values, or adjusted estimates for the primary outcome. It therefore does not communicate the statistical precision of each mean or a formal comparison with zero. The record also does not state what magnitude of score difference would be clinically meaningful. A numerical difference cannot be labeled important to patients or clinicians without an appropriate threshold and context, neither of which is reported.

The findings do not establish whether observed cohort differences arose from the dose, cohort characteristics, random variation, or other factors. The posted summaries do not include a pooled dose effect, a direct test between high and low dose, or a formal test of differences among cohorts. A pattern across separate descriptive estimates is not a substitute for such comparisons.

The results also do not address scar appearance beyond the Week 13 assessment, or establish effects in other types of surgery or populations. The primary analysis is restricted to the defined completer population with the required assessment and available VAS data. The record does not describe the impact of missing data or provide a broader analysis population for comparison.

Accordingly, the defensible reading is limited: the registry posts cohort-specific means and standard deviations for paired scar-score differences, along with small outcome counts. Those values characterize the observed data under the recorded endpoint definition. They do not establish that EXC 001 improves scar appearance, that it has no effect, that the doses are equivalent, or that a dose-response relationship exists. The registry record does not report enough inferential or missing-data detail to support those conclusions.

14. Why This Trial Matters Statistically

This trial is statistically notable for its within-subject comparison. Each participant's EXC 001-treated scar is compared with a placebo-treated scar, and the primary result is a mean paired difference. That structure is distinct from comparing two independent groups: the analyzed quantity is the difference within a participant. For readers, keeping the paired unit of analysis clear helps prevent misreading the participant counts or interpreting the values as separate treatment-arm averages.

The endpoint also makes direction explicit. Since the score runs from best to worst and the difference is EXC 001 minus placebo, a negative mean indicates a lower average score for EXC 001-treated scars. That sign convention is essential for understanding the reported estimates. At the same time, direction is not the same as precision or statistical evidence. With no confidence intervals or test results reported, the means remain descriptive.

The results are split by cohort and dose, and the estimates do not all point in the same direction. This is a reminder that multiple descriptive comparisons can be difficult to summarize as one overall message. The registry record does not report a pooled analysis, a formal dose contrast, or a multiplicity strategy. The outcome counts are also small within each listed comparison, making it important not to overread differences between the displayed means.

The trial illustrates why the analysis population and missing-data rules are part of the statistical result, not merely administrative details. The primary endpoint is reported for completers meeting specified assessment and dose-missed criteria. The record does not give a participant flow or explain missing observations, so the scope of the reported means must remain tied to that defined population.

Finally, the study's registry entry distinguishes descriptive outcome reporting from inferential analysis. It includes means and standard deviations but no posted primary outcome analysis results such as p-values or confidence intervals. That distinction is useful in clinical research: a numerical estimate can be reported without a documented conclusion about its precision, statistical significance, or clinical importance.

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 primary endpoint is a visual assessment of blinded photographs, but the registry record does not describe the panel's composition, scoring procedures, training, agreement between assessors, or methods for resolving differing ratings. It does not report how photographic blinding was maintained or evaluated. These omissions limit assessment of how consistently the score was assigned, even though the endpoint description specifies the scale and direction.

The primary results are restricted to Week 13 and to a completer population. The record does not report baseline scar scores or change from baseline, and it does not provide later follow-up results for the primary endpoint. It also does not explain the missing primary outcome data, provide a participant flow, or describe how incomplete paired observations were handled. The effect of these limitations on the reported means cannot be determined from the registry record.

The registry presents results separately by cohort and dose but does not report an overall estimate, formal dose comparisons, confidence intervals, p-values, or an adjustment for multiple comparisons. Without those details, it is not possible to assess statistical precision or establish whether apparent differences across entries exceed random variation. No threshold for a clinically meaningful difference is reported either.

The listed dose entries and cohort counts are not accompanied by a detailed account of cohort assignment, dose-selection rationale, exposure, or the sequence of Part A and Part B procedures. The record does not report a statistical analysis plan or the sample-size justification used for the trial. The planning assumptions described for illustrative calculations are not the trial's own design justification.

Safety reporting is similarly limited: serious-event counts are listed, but death counts are not reported in the registry record, and the summary does not separate Part B adverse events by EXC 001 versus placebo. Event details and comparative safety estimates are not reported. These features restrict interpretation to the recorded counts rather than a comprehensive treatment-specific safety comparison.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Efficacy Study of Different Dose Levels of EXC 001 to Improve the Appearance of Scars in Subjects Undergoing Elective Abdominoplasty — NCT01038297.
• Registry record last updated 2021-09-20; status last verified 2021-08.
• Results first posted 2021-09-20.
• 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.

19. Record Summary

NCT01038297 is a completed phase 2 randomized, double-blind study sponsored by Pfizer, evaluating EXC 001 for incision scars in people undergoing elective abdominoplasty. The registry lists enrollment of 30, a start date of 2009-12-01, and a primary completion date of 2010-07-07. The study is described as within-subject controlled, with placebo as the comparator.

The primary endpoint is the Part B Expert Panel Scar Assessment Score at Week 13. It measures the within-participant difference between EXC 001-treated and placebo-treated scars on a 100 millimeter visual analog scale, with higher scores indicating worse scar severity. Means and standard deviations are reported for high- and low-dose entries across three cohorts. The reported mean differences vary in direction across those entries.

The primary outcome is defined for a completer population. The registry does not report inferential test results, confidence intervals, a multiplicity strategy, or detailed missing-data methods. Serious adverse event counts are listed as 0 for the reported groups; death counts are not reported in the registry record. The posted information supports a descriptive reading of the recorded outcome and safety counts, with substantial limits on conclusions about precision, comparative effects, and clinical importance.