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 Safety for Frequent Use Conditions of Hair Removal Device (NCT01348789), a na na study. The primary outcome is Percentage of Participants With Device Related Anticipated Skin Effects, Serious Adverse Events, or Adverse Events..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01348789 |
| Phase | NA |
| Condition | Hair Removal |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 37 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Syneron Medical |
| Results posted | Yes |
2. Clinical Question
Population
Participants with the condition listed as Hair Removal who received at least one treatment, according to the primary outcome’s stated analysis population. The registry record lists an enrollment of 37.
Intervention
Treatment with the Hair2Go (Mē) device, assessed under frequent-use conditions.
Comparator
No separate comparator group is listed. The study is described as a single-group, before-after design.
Primary question
What percentage of participants had device-related anticipated skin effects, serious adverse events, or adverse events during follow-up of up to 3 months?
The study’s stated purpose was to measure the safety of the device when used frequently. The primary question is about the proportion of participants experiencing specified safety outcomes, rather than a contrast between treatment groups. Dermatologist assessment covered immediate skin reactions and longer-term side effects and adverse effects. Listed findings included erythema, edema, bleeding related to mechanical shaving, blister or ulcer formation, pigment or textural changes, scarring, infection, pruritus, post-inflammation reactions, and allergic reactions.
The registry also lists tolerability of each procedure separately for light and dark skin, and hair clearance, as secondary outcomes. Results for those outcomes are not reported in the registry record. The primary outcome estimate is also not reported in the registry record, so the central question cannot be answered from a reported percentage or confidence interval.
3. Trial Design
The registry describes a prospective, open-label study with a before-after design. Its official title identifies the study as evaluating the safety of the Hair2Go device under frequent-use conditions. The intervention was Hair2Go (Mē), a device, and the condition was Hair Removal. The study is listed as single-group, with no masking and no allocation scheme reported. No separate control group is described.
Enrollment was 37. The study began in 2011-03, reached primary completion in 2012-06, and is marked completed. The primary outcome timeframe was up to 3 months. The registry does not report the exact schedule or number of treatments, the duration between treatment visits, or the details of any assessment visits. Those aspects of exposure and follow-up therefore cannot be reconstructed from the record.
The primary outcome’s stated population is an intention-to-treat analysis of all participants who received at least one treatment. The registry does not report the number who received treatment or the number included in a primary outcome analysis. The safety results list 37 participants at risk for serious adverse events and 37 at risk for other adverse events. These are the denominators reported for those event counts and should not be treated as an independently confirmed analysis population.
Because the study has a single group and before-after structure, it does not provide a concurrent treatment-group comparison. Before-after observations can describe outcomes over the study period, but without a separate comparator they do not isolate the effect of the device from other influences. The registry record does not report a protocol-level statistical plan, sample-size justification, interim analyses, or details of how repeated treatments were incorporated into the 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
| Stage | Hair2Go (Mē) |
|---|---|
| STARTED | 37 |
| COMPLETED | 33 |
| NOT COMPLETED | 4 |
Reasons for not completing this period:
| Reason | Hair2Go (Mē) |
|---|---|
| Protocol Violation | 2 |
| Withdrawal by Subject | 2 |
Analysis population for the primary outcome, as defined in the registry: Intention to treat analysis - all participants that received at least 1 treatment.
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.
| Characteristic | Unit | Hair2Go (Mē) |
|---|---|---|
| Participants analysed | 37 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 37 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age Continuous | years | 32.5 (SD 8.1) |
| Sex: Female, Male: Female | Participants | 29 |
| Sex: Female, Male: Male | Participants | 8 |
| Region of Enrollment: United States | participants | 37 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Device Related Anticipated Skin Effects, Serious Adverse Events, or Adverse Events., measured over Up to 3 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of particpants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of participants with device-related anticipated skin effects, serious adverse events, or adverse events. It is a participant-level safety measure: it asks whether a participant experienced a qualifying event during the stated follow-up, rather than how many treatment sessions were completed or how many episodes each participant had. The registry identifies the timeframe as up to 3 months and lists a 95% confidence interval as the measure of dispersion.
The endpoint description says immediate skin reactions and longer-term side effects and adverse effects were evaluated on site by a dermatologist. The specified findings include transient effects that disappear within < 24 hours, prolonged erythema or edema, mechanical-shaving bleeding, blisters, ulcers, pigment or textural changes, scarring, infection, pruritus, post-inflammation reactions, and allergic reactions. The description also states that safety would be confirmed if no device-related serious adverse event occurred.
Combining specified skin effects with serious and other adverse events can provide a broad account of safety observations. However, the registry record does not report the primary percentage, its confidence interval, or event counts for the full endpoint. The separately listed adverse-event counts therefore cannot, on their own, stand in for a result on the complete primary endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a safety-focused study and reports adverse-event counts for the Hair2Go (Mē) group. It lists 0 serious adverse events among 37 participants at risk and 0 other adverse events among 37 participants at risk. These are the posted counts for those event categories. They do not supply a reported estimate for the primary endpoint, which also includes anticipated skin effects, or a confidence interval for that endpoint.
The distinction between the event categories matters. The primary outcome includes a defined set of expected or anticipated skin effects as well as serious adverse events and adverse events. The adverse-event results alone do not show how many participants experienced each listed skin reaction, whether events were transient or prolonged, or whether any of those observations met the primary endpoint definition. The registry record does not report those details or the primary outcome percentage.
A zero event count in a study group describes what was recorded during the study; it does not establish that the underlying risk is zero. In general, an estimate based on a finite group remains uncertain, and a confidence interval communicates some of that uncertainty. Although the endpoint specifies a 95% confidence interval, the interval is not reported in the registry record. No precision estimate can therefore be interpreted for the primary endpoint.
The design also limits causal interpretation. This was a prospective, open-label, single-group study with a before-after design, not a randomized comparison. There is no separate control group against which to distinguish device-associated changes from background events, measurement variation, or other influences. Open-label assessment can also affect how subjective symptoms are reported or interpreted, even though the endpoint description says a dermatologist evaluated the skin findings.
The registry lists 37 enrolled participants, but that enrollment figure does not establish how many received treatment, completed follow-up, or contributed data to each outcome. The primary population is defined as participants who received at least one treatment, and the actual number analyzed is not reported in the registry record. Missing outcome data, withdrawals, and their handling are also not reported. Consequently, the event counts should be read with their stated at-risk denominators, not as proof that every enrolled participant had complete ascertainment for every outcome.
Overall, the posted safety counts document no recorded serious or other adverse events in their listed categories during the study. They do not provide the complete primary endpoint result, quantify uncertainty around that result, or establish comparative safety. Results for tolerability and hair clearance are not reported in the registry record. Any broader conclusion would go beyond the outcome information recorded.
9. Statistical Methods Explained
The primary outcome is expressed as a percentage of participants with one or more qualifying safety findings. For a participant-level proportion, the numerator is the number of participants who meet the outcome definition and the denominator is the number of participants assessed for that outcome. The registry’s primary outcome population is described as all participants who received at least one treatment. The primary percentage and the analysis denominator are not reported in the registry record, so the proportion cannot be independently interpreted from the posted results.
The listed outcome dispersion is a 95% confidence interval. In general, a confidence interval expresses the statistical uncertainty around an estimated quantity under the assumptions of the method used. It is not a guarantee that the true value lies within the particular interval, nor does it account automatically for biases, missing data, or limitations in outcome ascertainment. Here, the registry record does not report the endpoint estimate or its interval, and it does not state the interval method. It is therefore not possible to assess the interval’s width or the assumptions used to calculate it.
The endpoint is a count-based safety outcome, but it includes more than the adverse-event counts listed separately. Its clinical definition includes anticipated skin effects and other specified reactions, as well as serious and other adverse events. The registry’s adverse-event results list zero recorded events in the serious category and zero in the other category, each with 37 participants at risk. Those counts do not specify the number of participants with the anticipated skin findings listed in the primary outcome description. Nor do they report event severity, timing, duration, recurrence, or attribution for each potential skin effect. The broad primary definition and the separately reported event categories should therefore be kept distinct.
In general, rare or uncommon outcomes can be difficult to characterize precisely when event counts are small. A group with no recorded events may still have uncertainty about the underlying event probability. The confidence interval is one way to express sampling uncertainty for a proportion, but no such interval for the full primary endpoint is reported in the registry record. A zero count is consequently a descriptive observation, not a demonstration that an event is impossible or that risk has been ruled out.
The study’s open-label, single-group, before-after design is relevant to interpretation, not just to the choice of a statistical formula. A single-group proportion describes observations among participants receiving the device; it does not estimate a contrast against an untreated or alternative-treatment group. Before-after assessments can describe changes over time, but causal attribution requires caution when no concurrent comparator is listed. The registry record does not report adjusted analyses or a method for handling repeated measurements across treatment visits.
The record lists no analyses. It does not report a statistical analysis plan, the method for constructing the primary confidence interval, an approach to missing observations, or a planned method for comparing light- and dark-skin tolerability. It also does not report interim analyses. The outcome’s specified 95% confidence interval is not sufficient to infer how it was calculated or whether it was adjusted for any design features.
Planning illustrations associated with the study use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Such calculations are hypothetical planning exercises, not observed power and not a description of the study’s original design. The registry record does not report a sample-size justification for this single-group study, and the observed primary endpoint effect needed to interpret those illustrations is not reported in the registry record. A planning calculation built around two arms should not be mistaken for evidence that this study included a comparator.
For general context, over-dispersion occurs when count variability exceeds what a chosen count model expects; accounting for it can prevent uncertainty from being understated. The registry record does not report a count model or a repeated-event analysis for this study, so there is no basis to say that over-dispersion was present or that any particular model was used. For the participant-level primary outcome, the key interpretive needs are the actual numerator, analysis denominator, interval estimate, and a clear account of missing assessments. Those details are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures. The primary safety outcome is a percentage of participants with specified device-related skin effects, serious adverse events, or adverse events. Listed secondary outcomes are procedure tolerability assessed separately for light and dark skin, and hair clearance. The record does not report results for these secondary outcomes or describe a strategy for controlling multiplicity across outcomes or comparisons.
Multiplicity is a general concern when several outcomes or analyses are examined: the more opportunities there are to identify an apparently notable finding, the more important it is to distinguish prespecified questions from exploratory ones. Without a reported analysis plan, the intended hierarchy of outcomes, any adjustment, and the interpretation of secondary analyses cannot be assessed. No analyses are listed in the registry record.
The primary population is defined as all participants who received at least one treatment, under the label “intention to treat.” The number meeting that definition is not reported in the registry record. The record also does not report how many participants completed follow-up, whether any outcomes were missing, why data might be missing, or how missingness was handled. Without that information, the extent to which the reported event counts represent complete follow-up cannot be established.
In general, missing data can affect an outcome estimate if the likelihood of missingness is related to participant characteristics or outcomes. Methods such as excluding participants with missing observations or making assumptions about unobserved outcomes can produce different interpretations. No such method is reported for this study. The registry’s at-risk denominators are available for the adverse-event counts, but they do not resolve missing-data questions for the primary endpoint or the other outcome measures.
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 |
|---|---|---|---|
| Hair2Go (Mē) | 0 | 37 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Hair2Go (Mē) | 0 of 37 |
The adverse-event results list 0 serious adverse events among 37 participants at risk and 0 other adverse events among 37 participants at risk. Read these as counts recorded in the registry for those event categories and denominators. They are not a reported percentage for the full primary endpoint, and they do not enumerate the anticipated skin effects included in that endpoint.
A zero count is not the same as proof that the event risk is zero. In general, an observed count describes the events recorded during follow-up; the underlying risk remains uncertain, particularly when the number of observed events is limited. The record does not report confidence intervals for these adverse-event counts. The deaths field is not reported in the registry record, so it should not be interpreted as a count of zero deaths.
The registry’s primary safety description says the immediate skin reaction and longer-term effects were evaluated by a dermatologist, but the detailed results for the listed skin findings are not reported in the registry record. The adverse-event counts therefore support only a narrow reading: no serious or other adverse events were recorded in the listed categories for the stated at-risk groups. They do not establish the absence of all skin effects or provide a comparative safety estimate.
12. What the Result Does, and Does Not, Mean
The posted results document zero serious adverse events and zero other adverse events in the respective groups of 37 participants at risk. This is a descriptive finding about the event counts recorded for the study. It is relevant to the safety question, but it does not answer every part of the primary endpoint, which also covers anticipated skin effects.
The primary outcome percentage and its specified 95% confidence interval are not reported in the registry record. The listed counts therefore cannot establish how many participants experienced any qualifying primary outcome, how precise an overall safety estimate would be, or how frequent particular skin reactions were. Results for tolerability and hair clearance are also not reported in the registry record.
The design determines what the observations can support. A prospective, open-label, single-group before-after study can record safety observations over time, but the absence of a separate comparator means it cannot provide a like-for-like estimate of how outcomes differ from those under another condition or treatment. The study’s enrollment and adverse-event denominators should not be read as evidence that every enrolled participant completed all assessments; the analysis population and missing-data details are not reported.
In general, a finding of no recorded events in a study group is not equivalent to demonstrating no risk. It may be consistent with a low event rate, incomplete ascertainment, or uncertainty that cannot be quantified without an estimate and interval. The registry record does not provide enough information to distinguish among those possibilities for the full primary endpoint.
Accordingly, the result supports a limited statement about the adverse-event categories as recorded, not a broad claim about the device’s safety under all conditions. It does not establish that anticipated skin effects did not occur, that the device caused or prevented a change, or that its safety differs from another option. Those conclusions require information not reported in the registry record.
13. Why This Trial Matters Statistically
This study illustrates why a safety endpoint needs both a clear event definition and a transparent estimate. The primary outcome describes a participant-level percentage and specifies a 95% confidence interval, but neither the percentage nor interval is reported. Without those quantities, readers cannot assess the frequency or precision of the full endpoint, even though adverse-event category counts are listed.
It also shows why outcome categories should not be conflated. A broad endpoint includes anticipated skin effects as well as serious and other adverse events. Zero counts in separately listed adverse-event categories do not establish zero occurrences across all the findings named in the primary definition. Clear reporting of each component would help readers understand which events were observed and how they contributed to the overall outcome.
The design is statistically important. A single-group before-after study can describe observations, but it cannot provide a concurrent comparison. That distinction governs the claims that can be made from the data, independent of how results are displayed or modeled. Open-label assessment and incomplete reporting of the analysis population and missing data add further uncertainty to interpretation.
Finally, the record distinguishes a planning exercise from the study’s actual design. Illustrations based on a fractional observed effect, two-arm allocation, and a normal approximation are hypothetical planning calculations. They are not observed power and do not turn a single-group study into a comparative trial. The example underscores the importance of matching a planning model to the design and being explicit about what estimates and assumptions are available.
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 registry record leaves important trial-specific details unreported. It does not give the primary endpoint percentage or its 95% confidence interval, and it does not provide participant counts for the anticipated skin findings that form part of that endpoint. The adverse-event results alone therefore provide an incomplete account of the primary safety question.
The record does not report treatment frequency, the number of sessions, exact follow-up visits, participant characteristics, or the number who completed follow-up. It defines the primary population as participants receiving at least one treatment but does not report the number included in that population or the number with complete endpoint data. Missing-data methods and reasons for any missing observations are not reported in the registry record.
There is no separate comparator group listed, and the study is open-label and single-group. As a result, the observations do not support a controlled comparison or isolate the device’s effect from other influences. The record also does not report the primary confidence-interval method, an analysis plan, multiplicity handling, interim analyses, or a sample-size justification. The fact that the study is marked completed does not fill these reporting gaps.
The safety counts should be interpreted within their listed categories and at-risk denominators. The deaths field is not reported in the registry record, and no conclusion about deaths can be drawn from that missing entry. Results for the secondary outcomes of tolerability and hair clearance are not reported in the registry record. These limitations constrain both the completeness and precision of the safety interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety for Frequent Use Conditions of Hair Removal Device — NCT01348789.
- Registry record last updated 2013-02-18; status last verified 2013-02.
- Results first posted 2013-02-18.
- 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
The registry record describes NCT01348789, “Safety for Frequent Use Conditions of Hair Removal Device,” as a prospective, open-label, single-group study with a before-after design. It evaluated the Hair2Go (Mē) device for Hair Removal and lists enrollment of 37. The study began in 2011-03, reached primary completion in 2012-06, and is marked completed.
The primary outcome was the percentage of participants with device-related anticipated skin effects, serious adverse events, or adverse events, assessed over up to 3 months. The registry lists 0 serious adverse events among 37 at risk and 0 other adverse events among 37 at risk. The primary outcome estimate and confidence interval, secondary outcome results, and analysis details are not reported in the registry record.