CoolSculpting and EMS for the Abdomen: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for CoolSculpting and EMS for the Abdomen (NCT03738891), a non-randomized na study. The primary outcome is Number of Unanticipated Adverse Device Effects (UADE).

2. Clinical Question

The study is titled as a feasibility study of EMS and CoolSculpting for abdominal contouring. Its brief summary describes evaluating EMS as an adjunctive treatment to CoolSculpting. The registry also names change in abdominal circumference and the percentage of participants reporting improvement on the S-GAIS as secondary outcomes. Those outcomes concern measurements of abdominal circumference and participant-reported aesthetic improvement, but numerical outcome results are not reported in the registry record.

The four cohorts allow the record to describe distinct treatment sequences, but they do not establish a randomized comparison between them. In particular, the registry record does not describe a common control group assigned by random allocation. The clinical question that can be addressed from the posted record is therefore chiefly descriptive: which regimens were studied, and what safety information was recorded for the cohorts? It does not support a causal estimate of how one regimen compares with another.

3. Trial Design

The registry identifies this as a completed feasibility study, with the title A Feasibility Study to Evaluate Electromagnetic Muscle Stimulation and CoolSculpting for Abdominal Contouring. The listed start date is 2018-11-07, the primary completion date is 2019-09-09, and the reported enrollment is 50. The phase is listed as NA. Zeltiq Aesthetics is named as the sponsor.

The design fields describe non-randomized allocation, no masking, and a single-group model. The intervention and cohort descriptions nevertheless distinguish four regimens: EMS only; EMS followed by CoolSculpting; CoolSculpting only; and CoolSculpting followed by EMS. The cohort descriptions specify 4 EMS sessions where EMS is used, and 3-6 CoolSculpting cycles where CoolSculpting is used. They do not establish randomized assignment or a direct, controlled comparison among these regimens.

The primary outcome is the number of UADEs during the study, assessed from enrollment through the final 12-week follow-up visit. The population description says participants in all cohorts were evaluated for adverse events and defines the primary endpoint population as participants who received at least one study treatment. The registry lists two secondary outcomes: change in pre-treatment and post-treatment abdominal circumference, and the percentage of participants reporting improvement on the S-GAIS.

The registry record does not report how participants were assigned to cohorts, whether cohort enrollment was consecutive, or the rationale for the different cohort sizes. It also does not report a sample-size justification, an interim-analysis plan, or a detailed statistical analysis plan. These omissions limit interpretation of how the study was intended to support comparisons or precision estimates.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: A total of 50 participants enrolled into Cohorts 1, 2, and 3. One subject enrolled in Cohort 3, received the treatment and completed all follow-up visits per Cohort 3 before subsequently rolling over to, and receiving treatment planned for Cohort 4. No other subjects were enrolled in Cohort 4. Efficacy data for Cohort 4 was excluded from analysis to avoid the perception of enhancing study enrollment. Data from this participant's treatment in Cohort 3 was included in all endpoint analyses.

Initial Cohort Assignment

Subsequent Cohort Assignment

Analysis population for the primary outcome, as defined in the registry: All Participants who received at least one study treatment. Participants in all cohorts were evaluated for adverse events.

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: Baseline characteristics data gathered and presented here by all participants enrolled with evaluable data. One subject enrolled in Cohort 3, received the treatment and completed all follow-up visits per Cohort 3 before subsequently rolling over to, and receiving treatment planned for Cohort 4. No other subjects were enrolled in Cohort 4. Baseline characteristics presented here are for all subjects at the time they were initially enrolled in the study.

6. Primary Endpoint

The registry lists the primary outcome as Number of Unanticipated Adverse Device Effects (UADE), measured over Enrollment through the final 12-week follow-up visit..

The primary endpoint is the number of unanticipated adverse device effects (UADEs), with the unit recorded as events. The stated timeframe runs from enrollment through the final 12-week follow-up visit. The registry describes tabulating the number of UADEs occurring during the study and defines the relevant population as all participants who received at least one study treatment.

A count endpoint is used to describe how many events were recorded, rather than to summarize a continuous measurement such as abdominal circumference. It can be useful in a device feasibility study because it makes the event burden observed during the study period explicit. General statistical context: a count alone does not describe the probability of an event for an individual, the timing of events, or whether multiple events occurred in the same participant. Those questions require additional information and an analysis suited to the data.

The registry reports cohort-level counts for serious and other adverse events, but those categories are not identified as UADE counts. They should not be treated as the primary endpoint result. A numerical UADE result, including any breakdown by cohort, is not reported in the registry record. The record also does not give a definition or adjudication procedure for classifying an event as an unanticipated adverse device effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count endpoint describe?

The primary outcome is a count: the number of UADEs recorded during the specified study period. A count answers how many events were tabulated, but it does not necessarily equal the number of participants who experienced an event. One participant may have more than one event, and an event count does not show when events occurred. The registry endpoint description does not report whether repeat events were possible or how they were handled, so those details are not reported in the registry record.

General statistical context: counts are often interpreted alongside the amount of observation, such as the number of participants followed and the duration of follow-up. A count without those details can be difficult to compare with counts from another study. Here, the endpoint timeframe is enrollment through the final 12-week follow-up visit, but numerical UADE results are not reported. The cohort-level safety summaries list numbers at risk and adverse-event counts, yet do not label those event counts as UADEs.

Why does non-randomized allocation matter?

Random allocation is a way to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics at the start of a study. This study is listed as non-randomized. Participants were described in four cohorts receiving different regimens, but the assignment process is not reported in the registry record. As a result, a difference between cohorts cannot automatically be attributed to the regimen. It could also be associated with differences in participant characteristics, enrollment patterns, or other factors.

General statistical context: adjustment methods can sometimes address measured differences, but they cannot guarantee removal of bias, especially when relevant factors were not measured. The registry record does not report adjusted analyses, baseline comparisons, or a detailed analysis plan. It therefore does not support an adjusted treatment-effect interpretation.

What is the consequence of no masking?

The study is listed as having no masking. Masking means keeping participants, clinicians, assessors, or analysts unaware of treatment assignment, depending on the design. In general, masking can reduce some sources of expectation or assessment bias. In a device study with visibly different treatment regimens, masking may be difficult, but the registry record does not discuss feasibility or any steps taken to limit bias. It also does not identify who assessed the secondary outcomes or whether outcome assessors were masked.

For participant-reported aesthetic improvement, awareness of treatment can be relevant to how responses are formed or recorded. For measured abdominal circumference, measurement procedures and assessor practices may matter. The registry lists those secondary outcomes but does not report their results or the measurement and assessment details needed to judge potential bias.

How should the safety counts be understood?

The posted safety summaries distinguish serious adverse events, other adverse events, and deaths. The serious-event affected counts are 0 in every cohort, while the counts for other adverse events are 0, 2, 1, and 0 across Cohorts 1 through 4. Deaths are recorded as 0 in each cohort. These categories should remain separate: the registry does not identify every serious or other adverse event as a UADE, and the primary endpoint is specifically the number of UADEs.

General statistical context: adverse-event counts are descriptive measures of events observed under the study's follow-up and recording procedures. A count does not indicate severity beyond the category assigned, and the term other adverse events should not be interpreted as a particular clinical diagnosis. The registry record does not provide event descriptions, dates, participant-level counts, or a detailed safety-analysis method. Those details are not reported in the registry record.

What does a planning illustration mean?

The registry entries describe planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. The effect to detect is expressed as a fraction of the observed effect. The assumptions distinguish participant-per-arm illustrations from total-event illustrations for time-to-event methods. No numerical planning results or observed effect estimates are reported in the record.

General statistical context: a sample-size illustration asks how much information a future study might need under stated assumptions. It is not an estimate of the probability that the current study detected a real effect, and it is not observed power. If an illustration is based on an observed effect, its value depends on that estimate and should not be mistaken for a prospective justification in the trial protocol. The registry record does not report the study's own sample-size justification, so the planning assumptions cannot be attributed to the original design.

What can a confidence interval add?

General statistical context: a confidence interval expresses uncertainty around an estimated quantity under a specified statistical method. It helps readers distinguish a precise estimate from one compatible with a broad range of values. The record does not report confidence intervals for the primary or secondary outcomes, and no interval should be inferred from the cohort event counts alone. For a count outcome, a suitable interval would depend on the definition of the event count, the relevant observation denominator, and the model or method used.

More generally, over-dispersion occurs when count data vary more than a simple count model expects. Accounting for it may be important when it is present, because standard errors and intervals can otherwise be too small. The registry record does not report a model for the primary endpoint or information with which to assess over-dispersion. This is general statistical context, not a description of an analysis documented for this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and two secondary outcomes: the number of UADEs, change in pre-treatment and post-treatment abdominal circumference, and the percentage of participants reporting improvement on the S-GAIS. It also reports 4 outcome measures and 0 analyses. The record does not provide numerical results for these outcomes or identify a statistical testing hierarchy.

Multiplicity arises when several outcomes or comparisons are examined. General statistical context: testing multiple questions can increase the chance that at least one result appears noteworthy by chance. A prespecified hierarchy or an adjustment procedure can address some multiplicity concerns, but neither a hierarchy nor an adjustment method is reported in the registry record. The record also does not describe any planned comparisons among the four cohorts, so no correction strategy for such comparisons can be evaluated.

Missing-data handling is not reported in the registry record. The available description does not state how missing abdominal-circumference measurements or S-GAIS responses were handled, whether participants with incomplete follow-up were included in outcome summaries, or how missing safety information was treated. General statistical context: missingness can affect estimates when the likelihood of a missing observation is related to participant characteristics or outcomes. Without the amount, pattern, and handling of missing data, the direction or size of any resulting bias cannot be assessed.

The primary population is described as all participants who received at least one study treatment, and participants in all cohorts were evaluated for adverse events. The registry record does not report additional analysis populations, such as a population based on treatment received or a population meeting a specified protocol definition. It also does not report interim analyses, stopping rules, or a detailed statistical analysis plan. These items should be treated as unreported rather than assumed to have been absent from the study conduct.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry's cohort-level safety figures list serious adverse events and deaths as 0 in all four cohorts. The numbers listed at risk are 20 for Cohort 1, 20 for Cohort 2, 10 for Cohort 3, and 1 for Cohort 4. The corresponding counts for other adverse events are 0, 2, 1, and 0. These are descriptive counts from the posted record, not comparative estimates.

A zero serious-event count means no serious events were recorded in that cohort's posted safety summary; it does not establish that serious events cannot occur. General statistical context: the interpretation of zero counts depends on the amount and duration of observation and on how events were defined and captured. The record describes follow-up through the final 12-week visit for the primary endpoint, but does not provide participant-level follow-up completeness or event-level details.

The primary outcome specifically concerns UADEs. The serious and other adverse-event categories are not identified in the registry as UADE counts, so the safety figures should not be substituted for a missing primary-endpoint result. The record does not report further details about the other adverse events or whether events occurred in different participants.

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

The record establishes that the study was registered as a feasibility study of EMS and CoolSculpting for abdominal contouring and describes four treatment cohorts. It also provides cohort-level counts for serious and other adverse events, with deaths recorded as 0 in each cohort. Those observations can be stated descriptively, within the limits of the event categories and follow-up described in the registry.

The record does not report numerical results for the primary endpoint of UADEs or for the secondary outcomes of abdominal-circumference change and S-GAIS improvement. Therefore, the presence of those outcomes in the registration is not evidence that a particular change occurred. Nor does the listed safety information establish the number of UADEs, because the registry does not equate the posted serious and other adverse-event categories with the primary endpoint.

The study is non-randomized, unmasked, and organized around different cohorts. The posted information consequently does not support a causal comparison of EMS alone, CoolSculpting alone, or either treatment sequence. The cohort counts should not be read as proof that one regimen produces better aesthetic outcomes or fewer adverse events than another.

General statistical context: feasibility studies can describe procedures, outcomes, and observed events, but their interpretation depends on the design and the completeness of reported results. A small or unevenly represented cohort can yield imprecise information, while a zero event count does not rule out events outside the observed participants and follow-up. The registry record does not report confidence intervals or other measures of uncertainty for these outcomes.

The reasonable scope of interpretation is therefore limited: the registry records the planned clinical questions, regimens, endpoint definitions, and some adverse-event counts. It does not report the primary or secondary outcome analyses needed to quantify abdominal-contouring results or to compare regimens. Any stronger claim about effectiveness or comparative safety would go beyond the numerical results reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically instructive because its registration places several distinct treatment regimens under a feasibility-study framework without randomized allocation. It shows why the names of several cohorts do not by themselves create a valid comparative trial. When participants are not randomized, the cohorts may differ in ways that affect outcomes, and those differences complicate causal interpretation.

The record also distinguishes a specific primary endpoint, the number of UADEs, from broader safety categories. Serious and other adverse-event counts are useful descriptions of the posted safety data, but they cannot be assumed to answer the primary question unless the registry identifies them as UADEs. Keeping endpoint definitions separate prevents a descriptive safety summary from being misread as a primary-outcome result.

The study has outcomes spanning event counts, a change in abdominal circumference, and a participant-reported aesthetic scale. Those outcomes capture different kinds of information and require different interpretations. A count describes recorded events; a change outcome requires pre-treatment and post-treatment measurements; and a reported-improvement percentage depends on participant responses and the definition of improvement. The registry names these measures but does not report their numerical results or analysis methods.

Finally, this record illustrates the importance of transparent reporting. Allocation procedures, missing-data handling, analysis populations, multiplicity methods, and precision estimates are not reported in the registry record. Without those details and the outcome results, readers should separate what is documented from what remains unknown. That discipline is especially important when interpreting safety counts from cohorts of different listed sizes and when considering whether a feasibility study supports a treatment comparison.

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 central limitation is that numerical results for the registered primary endpoint and secondary outcomes are not reported in the registry record. The posted adverse-event figures do not fill that gap because the serious and other event counts are not identified as UADE counts. No numerical results for abdominal-circumference change or S-GAIS improvement are given.

The design is non-randomized and unmasked, and the cohort regimens differ. The registry record does not report how participants entered each cohort, baseline characteristics, or methods for adjustment. Cohort comparisons could therefore be affected by selection and other differences, and cannot be interpreted as randomized treatment effects.

The safety figures list 20, 20, 10, and 1 participants at risk across the four cohorts. The record does not explain the cohort allocation process or reconcile these safety counts with the reported enrollment of 50. This should be treated as an unresolved reporting detail, not as a basis for inferring which participants were included or why the figures differ.

Additional limitations include the absence of reported event descriptions, participant-level safety data, follow-up completeness, confidence intervals, missing-data methods, and detailed outcome-analysis procedures. The record lists 0 analyses and does not report a statistical analysis plan, sample-size justification, or multiplicity approach. These gaps constrain assessment of precision, bias, and the robustness of any outcome interpretation. They do not establish that such methods or details were absent from study conduct; they are simply not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: CoolSculpting and EMS for the Abdomen — NCT03738891.
• Registry record last updated 2025-05-16; status last verified 2025-05.
• Results first posted 2025-05-16.
• 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

The registry identifies NCT03738891 as a completed feasibility study sponsored by Zeltiq Aesthetics, with reported enrollment of 50. The listed study dates are 2018-11-07 for start and 2019-09-09 for primary completion. The phase is NA, allocation is non-randomized, masking is none, and the model is single group.

Four cohorts are described: EMS only, EMS followed by CoolSculpting, CoolSculpting only, and CoolSculpting followed by EMS. The primary endpoint is the number of UADEs through the final 12-week follow-up visit. Secondary outcomes are abdominal-circumference change and S-GAIS improvement.

The posted safety figures record no serious adverse events or deaths in any cohort, with other adverse-event counts of 0, 2, 1, and 0 across the four cohorts. Numerical results for the primary and secondary outcomes, and detailed statistical analyses, are not reported in the registry record.