Non-Invasive Cooling of Fat Cells: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Non-Invasive Cooling of Fat Cells (NCT00762437), a na na study. The primary outcome is Percentage of Participants With Visible Improvement in Treated Area.

2. Clinical Question

This is a descriptive question about observed outcomes in a treated group, not a randomized estimate of a treatment effect relative to a control. The endpoint concerns visible improvement, as judged by investigators, rather than a stated quantitative measure of fat volume or a participant-reported assessment. Participant Satisfaction is listed as a secondary outcome, but its result is not reported in the registry record. The study’s scope is therefore defined by the recorded investigator assessment of visible change and the listed satisfaction outcome; the record does not establish how consistently outcomes were assessed across body sites or how participant assessments were incorporated.

3. Trial Design

The registry describes a prospective clinical study of non-invasive cooling of subcutaneous fat. Its status is COMPLETED, and the recorded enrollment is 175. The study start is listed as 2008-01, with primary completion on 2009-11-17. Zeltiq Aesthetics is the named sponsor. The phase entry is NA.

The design is single-group, with no masking. Allocation is recorded as NA, and the registry identifies the study as not being a randomized comparison. The arm description names a Treatment Group, but no like-for-like control arm is recorded. These features matter for interpretation: an observed outcome in this group describes what was recorded among participants receiving the device, but by itself it does not distinguish device-related change from other explanations for change over time.

The listed intervention is the Zeltiq Dermal Cooling Device, categorized as a device. The brief study summary states that the purpose was to evaluate whether cold exposure would consistently result in a reduction of subcutaneous fat. Further details about treatment settings, the number or timing of treatment sessions, eligibility criteria, follow-up procedures, and protocol conduct are not reported in the registry record.

The primary outcome was the percentage of participants with visible improvement in the treated area, assessed by an investigator at 4 months. Participant Satisfaction is listed as a secondary outcome. There are 2 outcome measures recorded and 0 analyses recorded. The record does not provide numerical outcome results for the primary endpoint or the secondary outcome. It also does not report the planned sample-size justification, a detailed statistical analysis plan, or whether any interim analyses were planned or conducted.

The absence of a control group is not a minor reporting detail: it defines what the study design can answer. The registry record can describe outcomes recorded in the treatment group, but a causal contrast against an untreated or alternative-treatment group is not available.

4. Participant Flow and Accounting

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

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants with evaluable data for each body site were included in this analysis.

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Visible Improvement in Treated Area, measured over 4 months.

The primary endpoint is the percentage of participants with visible improvement in the treated area at 4 months. The registry describes investigator assessment as the means of documenting any visible improvement in the treatment area. The endpoint is therefore binary at the participant level: a participant is classified according to whether visible improvement is recorded or not. The registry does not report further scoring criteria or the threshold used to classify improvement.

This kind of endpoint can give a direct descriptive account of how often an assessment category was recorded in the study group. A percentage is interpretable as a proportion of the participants included in the relevant assessment, rather than as a measure of the amount of change for each individual. It does not, on its own, describe the size of visible change or establish why that change occurred.

The registry specifies a 95% confidence interval as the dispersion measure for the primary endpoint. In general, a confidence interval conveys uncertainty around an estimated quantity: a narrower interval indicates greater precision, while a wider interval indicates less precision. The numerical percentage and its interval are not reported in the registry record, so neither the observed frequency nor its statistical precision can be evaluated from the posted information.

The endpoint population is described as participants with evaluable data for each body site included in the analysis. The registry does not state how many participants contributed evaluable data at each site, or how participants with missing or unevaluable assessments were handled. Those details are important for understanding exactly which participants the percentage represents.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a binary outcome expressed as a percentage. In general, a binary outcome places each assessed participant into one of two categories, such as visible improvement recorded or not recorded. The percentage describes the share in the category of interest among the participants included in the analysis. It does not measure the degree of improvement for each participant. The registry record does not report the numerical result, so the observed percentage cannot be stated.

What does a confidence interval convey?

The registry specifies a 95% confidence interval for the primary outcome. In general, a confidence interval is an uncertainty interval around an estimate. It reflects the variability that would arise from sampling under the assumptions of the method used. It is not a guarantee that the interval contains a fixed true value, and it does not address every source of uncertainty. For example, an interval does not remove limitations caused by a single-group design, an assessment process, or missing outcome data.

The interval’s width is relevant to precision: a wider interval indicates greater uncertainty about the estimated percentage, while a narrower interval indicates more precision. Because the registry does not report either the percentage or the interval bounds, readers cannot judge the precision of the primary estimate from the record. The record also does not identify the exact method used to calculate the interval.

Why does the single-group design matter?

In general, an uncontrolled study estimates outcomes within the group that was studied. A comparison between groups is needed to estimate how outcomes differ under distinct assigned conditions. This study is recorded as single-group, with allocation listed as NA and masking listed as NONE. It therefore does not provide a randomized comparison with a concurrent control group. Even if a within-group change is observed, a single-group result cannot by itself isolate the role of the intervention from other possible influences.

Random allocation, when used, can help make comparison groups similar on average with respect to measured and unmeasured characteristics. That principle is not a description of this study: the registry identifies no randomized comparison. Likewise, masking can reduce the influence of knowledge about treatment assignment on some assessments, but masking is recorded as NONE. The record does not describe other measures used to support consistent outcome assessment.

How should the analysis population be understood?

The registry states that participants with evaluable data for each body site were included in the primary analysis. In general, an analysis population defines who contributes information to an estimate. If some participants do not have evaluable measurements, the analyzed group may differ from the full enrolled group. The registry does not give the number assessed at each body site, the reasons for unevaluable data, or a missing-data method. Those omissions prevent a detailed assessment of the relationship between enrollment and the endpoint denominator.

The study enrolled 175 participants, but enrollment alone does not establish how many contributed to each site-specific primary assessment. The endpoint population should therefore be understood according to the registry’s evaluability description, not assumed to include every enrolled participant at every site.

What can a planning illustration tell readers?

General sample-size calculations estimate the number of participants that may be needed for a planned comparison under stated assumptions. The planning illustration associated with this record uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. For time-to-event outcomes, such illustrations use a total number of events; other illustrations express participants per arm.

These are planning assumptions, not evidence that the study used that design. The actual study is single-group, so the two-arm assumptions do not describe its recorded allocation. The registry record does not report the trial’s own sample-size justification or the effect size used for planning. Any planning figures should be read as illustrations of assumptions, not as a description of the study’s protocol or as observed power. Observed power is not a substitute for interpreting an estimated effect and its uncertainty.

What is not established by the analysis record?

The registry records 2 outcome measures and 0 analyses. It does not report a detailed statistical analysis plan, particular hypothesis tests, adjustment methods, interim analyses, or a multiplicity strategy. These items should not be inferred from a confidence-interval label or an endpoint description. In general, multiple outcomes can create multiple opportunities to identify a result that appears notable by chance, so planned interpretation and adjustment can matter. Whether and how that issue was addressed is not reported in the registry record.

Finally, statistical precision and causal interpretation are separate questions. A confidence interval can describe uncertainty around a proportion, but it cannot compensate for the absence of a control group or resolve uncertainty about assessment and missing data. In this record, the numerical outcome and interval are not reported, so even the descriptive estimate’s precision remains unknown.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Back Fat", "Love Handles")
n      <- c(69, 58)
events <- c(45, 48)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Back Fat  69  45  65.2  52.8  76.3  53.4  75.4  53.4  75.4
ARM  Love Handles  58  48  82.8  70.6  91.4  71.1  90.4  71.0  90.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures: the primary outcome of visible improvement in the treated area and the secondary outcome of Participant Satisfaction. It records 0 analyses. No numerical result for either outcome is reported in the registry record. The record does not state whether statistical tests were planned, whether outcomes were assessed at multiple time points or sites beyond the primary endpoint description, or whether any adjustment for multiple comparisons was intended.

In general, multiplicity arises when several outcomes, comparisons, or analyses are considered. The more questions examined, the greater the chance that some result may appear notable by chance. This does not mean that every analysis requires the same adjustment; the appropriate approach depends on the planned questions and analysis strategy. The registry record does not report a multiplicity plan, so it is not possible to determine how the study intended to address this issue.

For the primary endpoint, the stated population includes participants with evaluable data for each body site. The record does not report the number of evaluable participants by site, the amount or pattern of missing data, the reasons assessments were unevaluable, or any method for handling missing observations. It also does not say whether participants with incomplete data were included in any alternative analysis population. These omissions limit assessment of how the endpoint population relates to the enrolled group.

The statistical analysis plan, sample-size justification, and any interim-analysis plan are not reported in the registry record. Accordingly, the listed outcome definitions should not be treated as a full account of the planned analyses.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The All Participants group records 175 participants at risk for serious adverse events, 0 affected by serious adverse events, and 0 deaths. For other adverse events, 175 participants are listed at risk and 12 are listed as affected. These are the counts recorded in the registry.

The serious-event count and the other-event count are separate entries. The record does not provide the terms for the other adverse events, and no top serious-event terms are listed. It also does not report event timing, severity detail for the other events, or additional information about how events were collected or attributed.

In general, an adverse-event count describes events recorded during a study; it does not by itself establish that an event was caused by the intervention. A count of zero serious adverse events in this group means none were recorded in the registry’s serious-event field for the listed participants at risk. It does not establish that no events could occur outside the recorded observation or reporting process. The registry record does not provide enough detail to assess the completeness of event ascertainment or to compare safety with another group, because no like-for-like control group is recorded.

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

The registry record establishes that a prospective, single-group study evaluated the Zeltiq Dermal Cooling Device and defined a primary outcome based on investigator assessment of visible improvement in treated areas at 4 months. It also records enrollment of 175 participants and lists Participant Satisfaction as a secondary outcome. These details describe the study question and design, but the numerical primary and secondary outcome results are not reported in the registry record.

Without the primary percentage and its 95% confidence interval, the size and precision of the observed visible-improvement result cannot be evaluated. The outcome definition does not tell readers how many participants were assessed as improved, how much visible change occurred, or how consistent assessments were across body sites. The record also does not state the criteria used to classify visible improvement.

The study has no like-for-like control comparison. In general, a single-group observation cannot show what would have happened to comparable participants in the absence of the intervention or under a different intervention. Thus, the registry information does not support a controlled estimate of the effect attributable to the device. This is a design limitation, not a numerical result.

The safety entries show 0 serious adverse events among 175 at risk, 12 other adverse events among 175 at risk, and 0 deaths. These counts are descriptive. The record does not provide enough detail to characterize the other events or establish their relationship to the device, and no comparison group is available for a comparative safety assessment.

The record does not report details needed to evaluate missing data, the analysis plan, or multiplicity. It states that primary assessments included participants with evaluable data for each body site, but does not give the evaluable denominators. As a result, readers cannot determine the degree to which the analyzed participants represent all enrolled participants for the endpoint.

In short, the record defines a descriptive endpoint and provides basic design and safety counts, but it does not provide the numerical outcome estimate needed to characterize visible improvement. The single-group design further means that the study record does not provide a randomized comparison of outcomes.

14. Why This Trial Matters Statistically

This study illustrates why outcome definitions, analysis populations, and design structure all matter when interpreting a clinical result. A percentage of participants with visible improvement sounds straightforward, but its meaning depends on the assessment criteria, who was assessed, and how uncertainty was quantified. The registry identifies investigator assessment and a 95% confidence interval, yet does not report the numerical estimate, interval bounds, or detailed assessment rules. Readers therefore have a defined endpoint without the result needed to judge its frequency or precision.

The single-group design is also central to statistical interpretation. A descriptive outcome can be useful for understanding what was recorded in a treated group, but it is not the same as a controlled comparison. Without a like-for-like control group, a causal contrast is unavailable. This distinction helps prevent an observed outcome from being read as proof that the intervention alone produced it.

The record’s stated analysis population—participants with evaluable data for each body site—highlights another practical issue. A study’s enrollment count does not necessarily tell readers how many contributed data to every outcome assessment. The site-specific evaluable counts and missing-data handling are not reported, so the denominator and representativeness of the endpoint cannot be fully assessed.

Finally, the record lists a secondary outcome, records 2 outcome measures, and reports 0 analyses. This makes clear that outcome definitions and outcome results are different kinds of information. The presence of an outcome in a registry does not establish that a result was posted or explain how multiple outcomes were interpreted. For statistical readers, the key lesson is to separate design description, endpoint specification, numerical estimation, and causal interpretation rather than treating them as interchangeable.

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.

Several limitations specific to this study affect interpretation. The registry records a single-group model and no randomized comparison. As a result, the study record does not provide a concurrent control group against which to interpret visible improvement or adverse-event counts. Masking is recorded as NONE, and the endpoint depends on investigator assessment. The registry does not describe criteria for visible improvement, assessor procedures, or steps used to support consistent assessment.

The primary endpoint is described at 4 months, but its numerical percentage and 95% confidence interval are not reported in the registry record. The secondary outcome, Participant Satisfaction, also has no posted numerical result. Although the record lists 2 outcome measures, it records 0 analyses and does not report a detailed analysis plan, statistical tests, or multiplicity handling.

The primary analysis population is described as participants with evaluable data for each body site. Site-specific denominators, the number of unevaluable assessments, reasons for missing data, and methods for addressing missing observations are not reported. Thus, the relationship between the 175 enrolled participants and the population contributing to each endpoint assessment cannot be fully assessed.

Further study details—including eligibility criteria, device-use procedures, follow-up beyond the listed endpoint timeframe, and the trial’s sample-size justification—are not reported in the registry record. The safety information is also limited to the recorded counts: event terms and further collection or attribution details are not given for the other adverse events. These limitations restrict both the assessment of endpoint reliability and the interpretation of the posted safety counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Non-Invasive Cooling of Fat Cells — NCT00762437.
• Registry record last updated 2025-05-25; status last verified 2025-05.
• Results first posted 2025-05-25.
• 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

NCT00762437, titled “Non-Invasive Cooling of Fat Cells,” is recorded as a completed prospective clinical study sponsored by Zeltiq Aesthetics. The study enrolled 175 participants and evaluated the Zeltiq Dermal Cooling Device in a single-group design. Allocation is listed as NA, masking as NONE, and phase as NA. The recorded study start is 2008-01, and primary completion is listed as 2009-11-17.

The primary endpoint was the percentage of participants with visible improvement in the treated area at 4 months, based on investigator assessment. The registry specifies a 95% confidence interval and says the analysis included participants with evaluable data for each body site. Participant Satisfaction is listed as a secondary outcome. The record lists 2 outcome measures and 0 analyses, but does not report numerical results for the primary or secondary outcome.

The All Participants safety group records 0 serious adverse events among 175 at risk, 12 other adverse events among 175 at risk, and 0 deaths. The record does not include a like-for-like control comparison or further detail sufficient to interpret event attribution.