CoolSculpting System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for CoolSculpting System (NCT04506307), a na na study. The primary outcome is Percentage of Photographs Correctly Identified by At Least 2 of 3 Blinded Reviewers From the Independent Physician Reviewer Panel.

2. Clinical Question

3. Trial Design

The registry identifies NCT04506307 as a completed, single-group study titled “CoolSculpting System.” Its official title describes noninvasive fat reduction with the CoolSculpting System. Zeltiq Aesthetics is listed as the sponsor, and Body Fat Disorder is the listed condition. The registry lists enrollment as 35. The listed study start date is 2020-03-13, and the primary completion date is 2022-08-24.

The study evaluated the safety and efficacy of multiple, simultaneous CoolSculpting cycles for noninvasive fat reduction. The intervention is identified as the ZELTIQ System, a device. The arm description says that the treatments were designed to assess whether fat could be reduced in the torso using a new applicator design. The available record does not describe a separate arm receiving a different treatment or no treatment.

Allocation is recorded as NA, masking as NONE, and phase as NA. The registry classifies the study model as single group. These entries do not support treating the study as a randomized comparison. The record does describe blinded independent reviewers for the primary photographic assessment, but that is distinct from masking participants or treatment providers: the registry lists no masking for the study overall.

The primary endpoint was based on reviewers’ ability to identify which series of torso photographs represented baseline, rather than on a reported direct measurement of fat volume. The primary assessment was scheduled for Week 12 after the final treatment, described as 18 weeks after the first treatment. The record lists 2 outcome measures and zero analyses. It does not report an analysis plan, sample-size justification, interim analyses, or a detailed account of how all enrolled participants were handled in the primary 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.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Per Protocol population consisted of participants who received 2 treatments and had a weight change of no more than 5% of total body weight at the time the 12-week assessments were performed compared to the weight obtained at the first treatment visit. In addition, participants with extensive tattoos in the treated area that could hinder the evaluation were excluded.

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: All enrolled participants who received at least 1 treatment.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Photographs Correctly Identified by At Least 2 of 3 Blinded Reviewers From the Independent Physician Reviewer Panel, measured over Week 12 post final treatment (18 weeks after first treatment).

The primary endpoint was the percentage of photographs correctly identified by at least 2 of 3 blinded independent physician reviewers. Reviewers received two series of torso photographs: one from baseline and one taken 12 weeks after the final treatment. The order of presentation was randomized by participant. Reviewers were asked to select the series representing baseline. Thus, the endpoint captures whether a majority of the reviewers could distinguish the baseline series from the post-treatment series, as judged from the photographs.

The assessment was scheduled for Week 12 after the final treatment, corresponding to 18 weeks after the first treatment. The stated unit is the percentage of images identified correctly. The protocol’s stated success definition was at least 70% correct identification of baseline images. This threshold describes the criterion used to define success; it is not itself the observed result.

Photographic review can provide a structured visual assessment, and blinding reviewers to the treatment information can reduce the influence of expectations on their judgments. As a general statistical point, a reviewer-based endpoint is still an indirect measure: it reflects image recognition under the specified review procedure, not necessarily the size of a change in fat or the experience of participants. The registry record does not report the observed percentage, confidence interval, or whether the stated threshold was met.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a percentage based on photographic classifications. For each review, the question was whether the reviewer could identify the baseline series from the baseline and post-treatment series. The endpoint counts an image as correctly identified when at least 2 of the 3 blinded independent reviewers selected the baseline series correctly. The reported unit is “% of images identified correctly.” The registry record does not report the number of images used in the endpoint calculation or the resulting percentage.

What does the confidence interval represent?

The endpoint lists a 95% confidence interval as its measure of dispersion. As a general statistical explanation, a confidence interval expresses uncertainty around an estimated quantity under the statistical method used to construct it. It is not a range containing a fixed proportion of individual participant outcomes. If an interval is narrow, the estimate is more precise under that method; if it is wide, the estimate is less precise. The registry record does not provide the primary estimate or its interval, and it does not state the method used to calculate the interval.

A percentage from a reviewer classification task depends on the observations included and on how the endpoint is defined. In this study, the definition requires agreement by at least 2 of 3 reviewers for an image to count as correctly identified. That rule provides a clear threshold for classifying each image, but does not show how consistently reviewers agreed with one another across all images. Reviewer-level agreement statistics are not reported in the registry record.

Why does study design matter for interpretation?

The registry describes a single-group study, with allocation listed as NA and masking listed as NONE. A single-group result can describe what was observed among participants treated in the study, but it does not directly compare outcomes against a concurrent control group. General statistical interpretation of a treatment effect usually depends on a suitable comparison that helps separate the effect of treatment from other influences. No such treatment comparison is listed in this record.

The primary photographic assessment does include blinded independent reviewers and a randomized order of photograph presentation by participant. In general, blinding reviewers can help limit expectations from influencing image judgments, and varying presentation order can help reduce an order-related influence. These safeguards apply to the outcome assessment; they do not alter the single-group treatment design. The record does not explain whether reviewers had access to other participant information or describe further procedures for resolving disagreement.

What is the role of the per-protocol population?

The primary endpoint description defines a per-protocol population as participants who received 2 treatments and whose weight change was no more than 5% of total body weight at the 12-week assessment compared with weight at the first treatment visit. This restricts the population for the primary assessment according to treatment receipt and a weight condition. Such a population definition is not the same as including everyone enrolled, and it can affect how broadly the result applies. The record does not give the number meeting these criteria or describe outcomes for participants who did not meet them.

The definition also contains an unfinished sentence about participants with extensive tattoos. Because that sentence is incomplete in the registry record, its exact role in defining the analysis population is unclear. The record does not report whether missing photographs or other missing endpoint information occurred, how missing information was handled, or whether any sensitivity analyses were performed.

What do the planning illustrations mean?

The planning illustrations are not the trial’s own design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event illustrations, the stated quantity is the total number of events; for other illustrations, it is participants per arm. These are hypothetical planning assumptions, not features of this single-group study’s reported design.

In general, a planning calculation asks how much information a future study might need to detect a chosen effect under stated assumptions. It does not say how likely the completed study was to detect an effect after the fact. Such a calculation is not “observed power.” Also, because the registry record does not report the observed primary endpoint result, the effect used in any illustration cannot be checked against the outcome information available in the record. A planning illustration should therefore not be mistaken for an observed result, a protocol requirement, or evidence that the study had a particular level of power.

The registry lists zero analyses. It does not report the statistical method used for the primary endpoint, any adjusted analysis, or any formal hypothesis test. The presence of a confidence-interval label and a success threshold does not establish which inferential procedure was used or whether the threshold was met. Those details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and identifies one primary outcome: the percentage of photographs correctly identified by at least 2 of 3 blinded reviewers. It also lists a secondary outcome concerning the number of participants with device- and/or procedure-related adverse events and device-related serious adverse events. The record reports zero analyses. It does not describe a statistical plan for controlling the chance of false-positive findings when multiple outcomes or analyses are considered. A multiplicity adjustment or testing hierarchy is not reported in the registry record.

The primary endpoint description names a 95% confidence interval and defines success as at least 70% correct identification of baseline images. The record does not give an observed endpoint estimate, interval, or test result. It also does not explain whether the threshold was intended as a descriptive benchmark, a formal statistical decision rule, or both. Without results and a defined analysis procedure, whether the endpoint met the criterion cannot be determined from the registry record.

The primary analysis population is described as per protocol and depends on receipt of 2 treatments and a weight-change condition. The record does not give the number of participants in that population, explain whether all eligible participants had evaluable photographs, or report how missing data were handled. It does not describe an intention-to-treat analysis or sensitivity analyses. The per-protocol description also contains an incomplete clause concerning extensive tattoos, leaving that part of the population definition unresolved.

General statistical practice treats missing outcome information as a potential source of uncertainty, particularly when inclusion depends on post-enrollment criteria. The record does not provide enough information to assess whether missingness occurred or could have influenced the endpoint. The planned approach to interim analyses, sample-size justification, and handling of multiple endpoints is not reported in the registry record.

11. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: urinary tract infection (2.9%), back injury (2.9%).

For the CoolSculpting of the Torso group, the registry lists 35 participants at risk for serious adverse events and 2 with serious adverse events. It lists 35 at risk for other adverse events and 11 under other adverse events. Deaths are listed as 0. The registry identifies Urinary tract infection and Back injury among the top serious adverse event terms, each reported as 2.9%.

These are descriptive safety counts from a single-group study. They do not compare event frequency with an untreated group or another treatment group. The counts should not be added together: the record does not establish whether the categories overlap or whether the same participant could contribute to more than one category. The top-term percentages should be read as recorded, not recomputed from the counts.

“At risk” identifies the group size used in the registry’s adverse-event reporting. The figures do not by themselves establish that an event was caused by the device or procedure. The record distinguishes serious events and device-related serious events in its secondary-outcome description, but does not provide a detailed event-level attribution account in the listed safety figures. Further details about timing, severity, duration, and resolution are not reported in the registry record.

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

The registry record describes a study designed to assess torso fat reduction after treatment with the ZELTIQ System. Its primary outcome uses independent reviewers’ identification of baseline photographs, with a stated success threshold of at least 70% correct identification. This tells readers what the study intended to measure and what criterion it specified, but not what the study observed.

The primary endpoint result is not reported in the registry record. Neither the percentage of photographs correctly identified nor its 95% confidence interval is available. It is therefore not possible to say from this record whether the stated success criterion was reached or how precisely the endpoint was estimated. The record also does not report a primary-outcome p-value or analysis details that would clarify a formal statistical decision.

Even if an endpoint result were available, its meaning would be specific to the photographic review procedure. Correctly identifying baseline images indicates that reviewers could distinguish the baseline series from the post-treatment series under the stated conditions. It would not, by itself, quantify the amount of fat reduction, establish how participants felt about the treatment, or demonstrate durability beyond the scheduled assessment. Those outcomes are not reported in the registry record.

The single-group design also limits causal interpretation. There is no separate control arm listed, so the record does not provide a like-for-like comparison against an alternative or no treatment. Blinded image reviewers and randomized presentation order are relevant safeguards for the assessment, but do not supply the missing treatment comparator.

The safety entries describe events recorded in the study and do not establish causation or comparative safety. The planning illustrations are hypothetical design calculations, not observed evidence or “observed power.” Overall, the registry contains useful information about the study question, outcome definition, and recorded safety counts, but its missing primary result and analysis details prevent a conclusion about the measured efficacy endpoint.

13. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a carefully specified measurement and a reported result. The registry defines a primary endpoint in terms of blinded reviewer judgments, identifies when photographs were assessed, and states a threshold for success. Yet the observed percentage and its confidence interval are not reported. A clear endpoint definition supports interpretation of what would be measured, but cannot substitute for the estimate needed to judge the result or its precision.

The photographic endpoint also illustrates how outcomes can be operationalized. Rather than reporting a direct numerical measurement of torso fat in the primary outcome description, the study asks whether reviewers can identify baseline photographs. Requiring at least 2 of 3 reviewers to identify the images correctly establishes a rule for classifying the image assessment. As a general statistical point, readers need both the operational definition and the resulting estimate to understand the strength and uncertainty of an outcome.

The single-group design highlights another central issue in clinical research: describing outcomes among treated participants is different from estimating a comparative treatment effect. Without a separate comparator arm, the record cannot show how the outcome would compare with an alternative course. Reviewer blinding can reduce some assessment biases, but it does not address all limitations associated with the absence of a treatment comparator.

The record also makes the analysis population important. The endpoint is defined for a per-protocol population based on treatment receipt and weight change, but the number meeting that definition is not reported. The incomplete tattoo-related clause further limits clarity about eligibility. These details matter because the population included in an analysis affects both the interpretation of the result and the information available to estimate it.

Finally, the registry’s planning illustrations should be kept separate from the trial’s observed findings. They use stated assumptions for hypothetical future planning, while the record does not provide the primary observed effect. This distinction helps prevent planning quantities from being mistaken for evidence about the completed study.

14. 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 of the registry record for interpreting this study is that it does not report the primary endpoint result. The percentage of images correctly identified and the stated 95% confidence interval are absent, as are a primary-outcome test result and detailed analysis methods. Accordingly, the endpoint’s observed magnitude, precision, and relationship to the success threshold cannot be assessed from the record.

The design is single group, with no separate comparator arm listed. The study can describe outcomes and events in its treated group, but the record does not provide a concurrent comparison to help distinguish treatment effects from other changes or influences. The registry lists masking as NONE, while describing blinded independent reviewers for the photographic endpoint; these statements concern different aspects of the study and should not be conflated.

The primary endpoint applies to a per-protocol population requiring 2 treatments and a weight change of no more than 5% at the assessment relative to the first treatment visit. The number of participants who satisfied that definition is not reported. The population description ends with an incomplete statement about extensive tattoos, so the full eligibility rule cannot be reconstructed. The registry also does not report how many participants had evaluable photographs or how missing endpoint data were treated.

Safety information is limited to the listed counts and top serious-event terms. Detailed event timing, severity, resolution, and attribution are not reported in the registry record. The listed counts are not a comparative safety analysis. The record further lacks a reported sample-size justification, interim-analysis plan, multiplicity approach, and detailed statistical analysis plan. These omissions limit the conclusions that can be drawn from the registry information alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: CoolSculpting System — NCT04506307.
• Registry record last updated 2025-03-10; status last verified 2025-02.
• Results first posted 2025-03-10.
• 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.

18. Record Summary

NCT04506307 is a completed single-group study sponsored by Zeltiq Aesthetics, with enrollment listed as 35. It evaluated the ZELTIQ System for noninvasive torso fat reduction. The primary outcome was the percentage of photographs correctly identified as baseline by at least 2 of 3 blinded independent reviewers at Week 12 after the final treatment, described as 18 weeks after the first treatment. The stated success definition was at least 70% correct identification.

The registry record does not report the primary endpoint result or its confidence interval. It lists 2 serious adverse events among 35 at risk, 11 under other adverse events among 35 at risk, and 0 deaths. No separate comparator arm is listed, and the primary analysis population is described as per protocol. The analysis population count, missing-data handling, and detailed statistical plan are not reported in the registry record.