This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Fat Layer Reduction in the Lateral Thighs Using CoolSculpting (NCT02324816), a na na study. The primary outcome is Safety of the Zeltiq CoolSculpting System in the Outer Thighs.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02324816 |
| Phase | NA |
| Condition | Body Fat Disorder |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 19 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Zeltiq Aesthetics |
| Results posted | Yes |
2. Clinical Question
The study asked about safety when the Zeltiq CoolSculpting System was used to treat subcutaneous fat in the lateral thighs with a colder treatment parameter. The registry describes a single treatment group and does not report a concurrent comparison group. The primary outcome was a tabulation of device- and/or procedure-related adverse events and unanticipated adverse device effects, collected from enrollment through the 12 week post-final treatment follow-up visit.
Population
Participants enrolled in a study concerning body fat disorder and non-invasive subcutaneous fat reduction in the lateral thighs. The registry reports an enrollment of 19.
Intervention
The Zeltiq CoolSculpting System, described as a cryolipolysis system using a colder treatment parameter for lateral-thigh treatment.
Comparator
No comparator group is reported. The study is listed as a single-group model, and allocation is recorded as NA.
Primary question
How many device- and/or procedure-related adverse events and unanticipated adverse device effects were recorded during the specified safety follow-up period?
A secondary outcome was the percentage of correctly identified pre-treatment photographs. The registry lists two outcome measures, but the posted results described in the record do not include a result for that secondary outcome. Nor does the record give a numerical result for the primary endpoint as a count of device- or procedure-related events. The adverse-event summary reports participants affected in serious and other categories; the relationship of every listed event to the device or procedure is not specified in that summary.
3. Trial Design
This was a completed, single-group device study sponsored by Zeltiq Aesthetics. The listed intervention was the Zeltiq CoolSculpting System, and the treatment group received CoolSculpting in the lateral thighs for non-invasive subcutaneous fat reduction. The official title specifies use of a colder treatment parameter, but the exact parameter is not reported in the registry record. The registry lists the phase as NA, allocation as NA, masking as NONE, and model as SINGLE GROUP.
Enrollment was 19. The study start date is 2014-11-14, and the primary completion date is 2015-03-13. The status is COMPLETED. These record dates identify the study timeline but do not establish when each participant received treatment or completed follow-up. The primary safety-outcome timeframe is described as enrollment through the 12 week post-final treatment follow-up visit.
A single-group design can describe events recorded among participants who received the intervention, but it does not make a direct comparison with an untreated or alternative-treatment group. Because no comparator is reported, differences in event experience between treatment strategies cannot be estimated from this design. The absence of masking is also recorded, but the registry does not describe whether outcome collection or event assessment used any additional safeguards against awareness of treatment.
The record does not report the study protocol, eligibility details, treatment schedule, exact colder parameter, or a statistical analysis plan. It also does not report the rationale for the planned enrollment. Those details should not be inferred from the study title or the number enrolled. The listed sponsor and intervention identify the study context, while the registry information supports only a limited description of its design and reported outcomes.
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
| Stage | Lateral Thigh Treatment Group |
|---|---|
| STARTED | 19 |
| COMPLETED | 19 |
| NOT COMPLETED | 0 |
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: Female subjects with visible fat bulges on the outer thighs were recruited for the study.
| Characteristic | Unit | Lateral Thigh Treatment Group |
|---|---|---|
| Participants analysed | 19 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 19 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 45.0 (31 to 59) |
| Sex: Female, Male: Female | Participants | 19 |
| Sex: Female, Male: Male | Participants | 0 |
| Race/Ethnicity, Customized: African American | Participants | 0 |
| Race/Ethnicity, Customized: Asian | Participants | 2 |
| Race/Ethnicity, Customized: Caucasian | Participants | 16 |
| Race/Ethnicity, Customized: Hispanic | Participants | 0 |
| Race/Ethnicity, Customized: Others | Participants | 1 |
| Region of Enrollment: United States | participants | 19 |
| Body Mass Index | kg//m^2^ | 26.5 (21 to 32.1) |
6. Primary Endpoint
The registry lists the primary outcome as Safety of the Zeltiq CoolSculpting System in the Outer Thighs, measured over Enrollment through 12 week post-final treatment follow-up visit.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled “Safety of the Zeltiq CoolSculpting System in the Outer Thighs.” It is expressed as a number of events. Its description calls for tabulation of device- and/or procedure-related adverse events and unanticipated adverse device effects. Event information was to be collected from study enrollment through the 12 week post-final treatment follow-up visit, with the investigator determining whether an adverse event was related to the device and/or study procedure.
A count endpoint is used to describe how many events were recorded under the endpoint definition. It differs from an outcome that measures the proportion of participants affected: one participant could potentially contribute more than one event, depending on the protocol's counting rules. The registry does not report those detailed rules or clarify how the primary count was analyzed. The adverse-event summary separately lists participants affected in serious and other categories, so those entries should not automatically be treated as the primary endpoint's complete event count.
Safety tabulations are useful for describing events observed during a defined collection period. They do not by themselves establish that an event was caused by the intervention, especially when a comparison group is absent. The registry says the investigator was to determine relatedness, but the posted summary does not give a detailed event-by-event relatedness account for the listed participants.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted safety summary lists 19 participants at risk for serious events, with 0 affected, and 19 at risk for other events, with 14 affected. Deaths are listed as 0. These are descriptive entries for the Lateral Thigh Treatment Group. They do not provide a comparative estimate because the record reports no control group.
The primary outcome description concerns counts of device- and/or procedure-related adverse events and unanticipated adverse device effects. The group summary, however, is framed in terms of participants affected in serious and other categories. The record does not explain whether the other-event category includes all non-serious events, how multiple events in one participant were counted, or how these summary categories map to the primary endpoint. As a result, the listed 14 should be read as the record's count of participants affected under “other,” not assumed to be a count of distinct events or a definitive count of events judged related to the device or procedure.
There is no reported confidence interval, comparative effect estimate, or detailed statistical analysis for the primary outcome. A point count alone conveys what was recorded in this group but does not show the uncertainty around an underlying event rate. In general, a confidence interval indicates a range of values compatible with the data under a specified statistical method; its width reflects both the amount of information and the method's assumptions. No such interval is reported for these safety figures.
The absence of listed serious events and deaths is a statement about the posted group summary, not proof that the underlying risk is zero. A study with a limited enrollment may fail to observe uncommon events, and a single-group study cannot distinguish background events from events attributable to treatment. These are general limitations of interpreting safety counts without a comparator and with limited information about follow-up completeness.
The registry also lists a secondary outcome concerning correct identification of pre-treatment photographs, but its result is not reported in the registry record. The record lists two outcome measures and one analysis, yet does not identify the analysis method or make clear which measure it concerns. The result therefore supports a narrow description of the posted safety counts; it does not establish a treatment effect, comparative safety, or the magnitude of any change in fat layer.
9. Statistical Methods Explained
The registry identifies a number-based safety endpoint, but does not report the statistical method used to analyze it. The concepts below are general explanations of ways count outcomes may be described; they are not claims about the analysis performed in this study.
What does a count outcome describe?
A count records how many events meet a defined endpoint over a specified observation period. For safety outcomes, interpretation depends on what qualifies as an event, how events are attributed, and whether repeat events in the same participant are counted separately. A participant count answers a different question from an event count: the first identifies how many people experienced at least one event, while the second can include multiple events for an individual. The registry's primary endpoint is described as a number of events, whereas its adverse-event group summary reports participants affected. The detailed counting rules and the relationship between those summaries are not reported in the registry record.
Why does the observation period matter?
A count has meaning in relation to the period over which events are collected. The primary endpoint description specifies enrollment through the 12 week post-final treatment follow-up visit. In general, counts collected over different lengths of follow-up are not directly comparable without accounting for observation time. Rates can incorporate time at risk, but they require suitable information on participants' follow-up and the analysis approach. The registry does not report participant-level follow-up duration, a rate estimate, or a method for handling incomplete observation.
How would a comparison change the interpretation?
In general, a comparison group helps distinguish the event experience associated with an intervention from events that would also occur in a similar group under another condition. A single-group study can report observed counts but cannot directly estimate a between-group difference or ratio. This record lists a SINGLE GROUP model and no comparator. Consequently, the posted safety figures are descriptive rather than comparative. No adjusted or unadjusted treatment contrast is reported in the registry record.
What role can uncertainty estimates play?
In general, an uncertainty interval around a count-based proportion, rate, or contrast communicates how imprecisely the quantity is estimated. The interval depends on the estimand, the statistical model, and assumptions about the data. A confidence interval is not a guarantee that the true value lies within its bounds; it is a measure interpreted under a specified repeated-sampling procedure. No confidence interval or uncertainty estimate for the primary safety endpoint is reported in the registry record. The posted counts therefore should not be read as precise estimates of event frequency beyond the observed study group.
Why can count data require special care?
In general, simple count models may assume a particular relationship between the average count and its variability. When the data vary more than the model assumes, uncertainty estimates may be too small if that extra variation is ignored; this is called over-dispersion. Repeated events may also cluster within participants, so treating every event as independent can understate uncertainty. These concerns matter when a study records event counts, but the registry does not report a model, a check for over-dispersion, or a method for accounting for repeated events.
What can be inferred from the analysis listing?
The registry lists one analysis and two outcome measures. It does not identify the analysis population, the statistical test or model, the handling of missing observations, or whether the analysis addressed the primary outcome, the secondary outcome, or both. The sample-size illustration associated with the study is described as planning based on the observed effect, rather than as the study's own design calculation. Such an illustration is not observed power and should not be mistaken for evidence that the trial was planned or conducted using that approach. The trial's sample-size justification is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures: the primary safety endpoint and a secondary outcome concerning the percentage of correctly identified pre-treatment photographs. It lists one analysis, but does not report which outcomes were included in that analysis, whether there were multiple tests, or whether any adjustment for multiple comparisons was planned or used. The approach to multiplicity is therefore not reported in the registry record.
Multiplicity matters in general when several outcomes or statistical tests are examined. Each additional test can create another opportunity for a result to appear unusual by chance. An analysis plan may address this through a prespecified hierarchy, adjustment procedure, or clear distinction between confirmatory and exploratory questions. The record does not provide enough detail to determine whether any such approach was relevant or applied. No result for the photograph-identification outcome is reported in the registry record.
Missing-data methods and the analysis population are also not reported in the registry record. The enrollment count is 19, and the safety summary lists 19 participants at risk in each of its serious and other categories. Those entries do not establish that every participant completed the specified follow-up or contributed complete data to every outcome. The registry does not describe withdrawals, missing assessments, exclusions, or any imputation or other method for handling incomplete information.
In general, missingness can affect interpretation if participants with incomplete follow-up differ in event experience or outcome measurement from those with complete records. An analysis population definition clarifies which participants contribute to each result. Without those details, the posted summaries can be described as recorded but cannot be assumed to represent a particular intention-to-treat, per-protocol, or other analysis population.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Lateral Thigh Treatment Group | 0 | 19 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Lateral Thigh Treatment Group | 0 of 19 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Lateral Thigh Treatment Group | 14 of 19 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Lateral Thigh Treatment Group |
|---|---|---|
| Prolonged swelling | Skin and subcutaneous tissue disorders | 4 of 19 |
| Prolonged bruising | Skin and subcutaneous tissue disorders | 2 of 19 |
| Erythema lasting > 2 weeks | Skin and subcutaneous tissue disorders | 2 of 19 |
| Cold with cough | Respiratory, thoracic and mediastinal disorders | 1 of 19 |
| 24 hour cold | General disorders | 1 of 19 |
| Rotator cuff pin adjustment | Surgical and medical procedures | 1 of 19 |
| Tendonitis flare up | Musculoskeletal and connective tissue disorders | 1 of 19 |
| Eczema | Skin and subcutaneous tissue disorders | 1 of 19 |
| Menopausal changes | Reproductive system and breast disorders | 1 of 19 |
For the Lateral Thigh Treatment Group, the adverse-event summary lists 19 participants at risk for serious events and 0 affected. It lists 19 at risk for other events and 14 affected. Deaths are listed as 0. These are the safety figures reported for the group; they are not a comparison between treatments.
The word “other” is the registry's category label. The record does not define it in enough detail to conclude that it represents a particular severity class or that each affected participant had exactly one event. In particular, the 14 is a count of participants listed as affected, not necessarily a count of distinct events. The summary also does not provide event terms, and no top serious-event terms are listed.
The primary endpoint description calls for tabulation of device- and/or procedure-related adverse events and unanticipated adverse device effects. It says the investigator would determine relatedness. The group summary does not identify which listed events were judged related, nor does it reconcile participant counts with the primary endpoint's event-count format. Thus the safety figures should be read as the categories and counts presented, not as a complete event-level account or a causal assessment.
In general, zero observed serious events does not establish that the chance of such an event is zero. The counts describe the enrolled study group and observation record; they do not alone estimate comparative risk or rule out uncommon events.
12. What the Result Does, and Does Not, Mean
The record describes a completed single-group study of the Zeltiq CoolSculpting System in the lateral thighs. It reports enrollment of 19 and gives descriptive safety figures: 0 participants affected in the serious-event category, 14 in the other-event category, and 0 deaths. These figures characterize what the registry lists for this treatment group; they do not quantify a contrast with another intervention or no treatment.
The primary endpoint was intended to tabulate device- and/or procedure-related adverse events and unanticipated adverse device effects over the stated follow-up period. The posted adverse-event summary does not provide event-level details or establish which entries were judged related. It also reports participants affected, while the primary endpoint is described as a number of events. That distinction limits how directly the summary can be interpreted as the primary endpoint result.
The design cannot show whether observed events occurred more or less often than they would have in a comparable group. Without a comparator, observed events cannot be separated from events that might occur without the intervention. Likewise, the safety counts alone do not establish that the device caused an event or that it prevented one. The registry's title and study objective do not substitute for comparative outcome evidence.
The record also does not report a result for the secondary photograph-identification outcome, an uncertainty estimate for the safety counts, or the statistical method and analysis population. It therefore does not establish the precision of an underlying event rate or provide a complete assessment of all listed outcomes. These omissions do not change the descriptive counts, but they limit the conclusions that can be drawn from them.
In general, a study result is most informative when the outcome definition, analysis, follow-up, and uncertainty are clear and when the design matches the question being asked. Here, the record supports a narrow account of the listed group and event categories. It does not support a comparative conclusion about safety or a claim about the size of any fat-layer reduction.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between describing outcomes and estimating comparative effects. The single-group design can document the safety counts recorded among participants who received the device. It does not provide the contrast needed to estimate how those counts differ from those under another treatment or no treatment. That distinction remains important even when a study has a clearly stated clinical objective.
The endpoint also illustrates why outcome definitions and reporting units matter. The primary endpoint is described as a number of events, while the adverse-event summary gives numbers of participants affected in serious and other categories. Counts of events and counts of people answer different questions. Without event-level definitions and a reconciliation of those summaries, a reader should avoid treating them as interchangeable.
Precision is another central issue. The registry gives the group counts but does not report confidence intervals or a statistical analysis method for the primary endpoint. In general, reporting an uncertainty estimate helps readers distinguish an observed count from a precise estimate of event frequency. A small or limited dataset can be particularly uninformative about uncommon outcomes even when no such event is observed.
Finally, the record illustrates the importance of reporting the analysis population, missing-data handling, and multiplicity approach. The registry lists two outcome measures and one analysis, but does not explain their relationship. These details help determine what the results represent and how confidently they can be interpreted. Their absence leaves the posted safety figures useful as descriptive information, while limiting broader statistical conclusions.
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 is the single-group design. No concurrent comparator is reported, so the study cannot estimate a between-group difference in event frequency or separate intervention-associated events from background events. The allocation field is NA, and the registry does not describe a randomization process. Masking is recorded as NONE.
The registry's safety reporting is limited in detail. The primary endpoint calls for a number of device- and/or procedure-related events and unanticipated adverse device effects, while the group summary reports participants affected in serious and other categories. Event terms, event-level counts, relatedness judgments for the summary entries, and rules for counting repeat events are not reported in the registry record. No top serious-event terms are listed.
The study enrolled 19 participants, but the record does not report a sample-size justification or the reasoning behind the planned enrollment. It also does not report follow-up completion by participant, withdrawals, missing outcome data, the analysis population, or how missingness was handled. The stated collection period does not establish that every participant contributed the same amount of observation time.
Statistical methods, uncertainty estimates, and the relationship between the one listed analysis and two outcome measures are not reported in the registry record. The secondary photograph-identification outcome has no reported result. The exact colder treatment parameter, detailed eligibility criteria, and treatment schedule are also not reported. These limitations restrict the conclusions to the descriptive registry information and leave the precision, completeness, and comparative meaning of the outcomes uncertain.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Fat Layer Reduction in the Lateral Thighs Using CoolSculpting — NCT02324816.
- Registry record last updated 2021-12-28; status last verified 2020-09.
- Results first posted 2020-09-24.
- 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.
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18. Record Summary
NCT02324816 is a completed single-group study sponsored by Zeltiq Aesthetics. It examined the Zeltiq CoolSculpting System for non-invasive subcutaneous fat reduction in the lateral thighs using a colder treatment parameter. Enrollment was 19; the study start date was 2014-11-14, and the primary completion date was 2015-03-13.
The primary outcome concerned tabulation of device- and/or procedure-related adverse events and unanticipated adverse device effects from enrollment through the 12 week post-final treatment follow-up visit. The safety summary lists 0 participants affected by serious events, 14 affected by other events, and 0 deaths. A secondary outcome concerned correct identification of pre-treatment photographs, but its result is not reported in the registry record.
No comparator is reported, and the registry does not report the statistical analysis method, uncertainty estimates, analysis population, missing-data approach, or sample-size justification. The posted safety entries are descriptive and do not establish comparative effects or causation.