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 Impact of Sensory Stimuli on Patient Preferences During Outpatient Surgery (NCT02958826), a registered phase not stated study. The primary outcome is Effect of Surgical Lights on Patient Preference.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02958826 |
| Phase | Phase not stated |
| Condition | Patient Satisfaction |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 160 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Missouri-Columbia |
| Results posted | Yes |
2. Clinical Question
Population
Patients completing an outpatient Mohs surgical procedure. The registry record does not report further eligibility details or describe the participants’ characteristics.
Intervention
The listed study activity is an anonymous questionnaire administered after the procedure. One group is described as receiving smoke evacuation during the study procedure.
Comparator
A group described as having no smoke evacuation also completed an anonymous questionnaire. The registry record does not state how participants were assigned to the groups, so the groups should not be treated as a confirmed randomized comparison.
Primary question
The primary outcome asks about patient preference related to surgical lights, measured as a percentage of participants. The broader study purpose also concerns surgical smoke and sounds and their relationship to satisfaction with outpatient Mohs surgery.
The central question is whether participants’ reported preferences about surgical lights differ in the context of the sensory experience of outpatient surgery. The stated primary outcome is not a clinical measure of surgical performance or a direct measure of the lights themselves. It is a questionnaire-based report of patient preference, collected immediately after the procedure and before the participant leaves the office.
The registry record describes smoke evacuation and no smoke evacuation groups, but it does not say that allocation was randomized or explain how the groups were formed. That matters because a difference in questionnaire responses, if reported, could reflect differences between the groups as well as any effect associated with smoke evacuation. The record also does not provide the actual questionnaire wording, response options, or a definition of what counted as a preference. As a result, the precise construct being measured cannot be reconstructed from the registry description alone.
3. Trial Design
The study is listed as completed and has an enrollment of 160. The sponsor is the University of Missouri-Columbia. The registry record gives a start date of 2016-10 and a primary completion date of 2017-07-01. Its stated purpose is to examine how surgical lights, surgical smoke, and surgical sounds relate to satisfaction with an outpatient Mohs surgical procedure.
The intervention is listed as a questionnaire, categorized as other. The two described groups are a Smoke Evacuation Group and a No Smoke Evacuation Group; both are described as receiving an anonymous questionnaire. The adverse-event listing names the other group Control Group. The record does not explain whether that label refers to the No Smoke Evacuation Group, so the labels should not be assumed to be interchangeable without qualification.
The primary outcome concerns preference related to surgical lights and is expressed as a percentage of participants. The questionnaire is described as being completed immediately after the participant has finished the Mohs procedure and before leaving the office. The record says that responses would be compiled and presented upon completion of the study in approximately one year, but it does not include the resulting outcome data.
Although the study description names lights, smoke, and sounds, the registered primary outcome specifically concerns lights. The record lists three outcome measures, but the other measures are not described in the information available. It does not state the allocation method, whether the study was randomized, whether any masking was used, or the planned statistical analyses. Those aspects of the design are therefore not reported in the registry record.
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 | Smoke Evacuation Group | Control Group |
|---|---|---|
| STARTED | 80 | 80 |
| COMPLETED | 80 | 80 |
| NOT COMPLETED | 0 | 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.
| Characteristic | Unit | Smoke Evacuation Group | Control Group | Total |
|---|---|---|---|---|
| Participants analysed | 80 | 80 | 160 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 27 | 24 | 51 |
| Age, Categorical: >=65 years | Participants | 52 | 55 | 107 |
| Sex: Female, Male: Female | Participants | 22 | 20 | 42 |
| Sex: Female, Male: Male | Participants | 56 | 52 | 108 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Effect of Surgical Lights on Patient Preference, measured over Questionnaire administered immediately after patient has completed Mohs surgical procedure. Questionnaire response data will be compiled and presented upon completion of the study in approximately one year..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the effect of surgical lights on patient preference, expressed as a percentage of participants. The questionnaire is administered immediately after the Mohs procedure, before the participant leaves the office. The registry description says that participants are asked about their experience with surgical lights.
A preference endpoint captures a participant-reported response to an experience. It can be useful when the research question concerns how people perceive or prefer aspects of care, rather than a laboratory measurement or a clinical event. A percentage expresses how common a particular response is among the participants included in its denominator. Interpreting that percentage requires knowing the exact question, response choices, how responses were classified, and how missing answers were handled. These details are not reported in the registry record.
The registry record does not report the observed percentage, a comparison between groups, or an uncertainty estimate. It also does not specify whether the primary light-preference outcome is intended to compare the smoke evacuation groups or to describe preferences across the study population. The broader purpose mentions satisfaction, smoke, and sounds, but those concepts should not be substituted for the stated primary endpoint. The endpoint is a questionnaire response concerning lights, not a direct measure of surgical quality or a complete measure of satisfaction.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the study as completed and records an enrollment of 160, but it does not report the primary outcome results. No observed preference percentages, between-group estimates, confidence intervals, or p-values are reported in the registry record. Accordingly, the record does not establish the direction or size of any difference in patient preferences related to surgical lights.
The group descriptions identify smoke evacuation and no smoke evacuation, and the adverse-event listing reports 80 participants at risk in each named group. These counts do not establish that the groups were formed by random allocation. The registry record explicitly does not state an allocation method, and the comparison is not a like-for-like control comparison. If results were available, differences between groups would therefore need to be interpreted with caution: group composition, procedure circumstances, or other factors could contribute to differences in questionnaire responses.
The outcome is a participant-reported preference measured immediately after surgery. Such responses describe what participants reported at that time under the questionnaire process. They do not, by themselves, indicate whether one sensory environment improves clinical outcomes or whether the same preferences would be reported in another setting. The record does not give the questionnaire wording, response categories, or the method for turning responses into a percentage. That limits the interpretation of the endpoint even apart from the absence of numerical results.
The record lists three outcome measures but does not provide the details of the other measures in the information available. It also records no analysis entries. This does not show that no analyses were conducted; it means that results of analyses are not reported in the registry record. Without reported estimates and their uncertainty, there is no basis in this record for judging how precisely any group difference was measured.
The serious adverse-event listing records zero serious events, zero other events, and zero deaths in each group, with 80 participants at risk in each. These are registry counts for the listed groups. They do not resolve the unanswered question about preference, and they should not be taken as evidence about outcomes or event reporting beyond what the record specifies. Overall, the registry description establishes the study question, timing, group labels, and some participant counts, but not the primary result or an inferential comparison.
9. Statistical Methods Explained
The registry record describes a binary-percentage outcome: a participant response is represented as a proportion or percentage of participants. In general, a binary outcome distinguishes between two response states, such as a response meeting a stated definition and one that does not. For this study, the exact response categories and the rule for classifying a preference are not reported in the registry record. That missing definition matters because it determines which responses contribute to the numerator and which participants are included in the denominator.
What would a percentage estimate mean?
In general, a percentage estimates how frequently a defined response occurs among the people included in the analysis. A percentage is easier to interpret when its denominator is clear. For a questionnaire outcome, readers also need to know whether every participant answered the item, whether unanswered items were excluded, and how responses that do not fit a simple category were treated. These details are not reported in the registry record, so the calculation behind the planned percentage cannot be fully assessed.
A percentage alone does not describe its precision. In general, a confidence interval gives a range of values compatible with the data under a specified statistical method. Wider intervals indicate less precision, while narrower intervals indicate greater precision. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record. The uncertainty around any difference between the smoke evacuation groups is therefore also not available.
What does a comparison require?
In general, comparing percentages between groups requires a clearly defined outcome, a known denominator for each group, and a suitable analysis plan. If group assignment is randomized, randomization can support a causal interpretation by balancing factors across groups on average. If allocation is not randomized or is not reported, the groups may differ in ways that also relate to the outcome. Here, the allocation method is not stated, and the registry record cautions that the arms are not a like-for-like control comparison. A group contrast, if results were reported, would need to be read as an association unless the study design and analysis justified a stronger interpretation.
The record does not report a statistical test or model for the primary outcome. It does not identify whether the intended analysis would compare percentages, adjust for participant or procedural characteristics, or use another approach. The number of analysis records is zero. This means that no analysis results are documented in the registry record; it does not establish what the investigators may have done outside that record.
How should p-values be understood?
In general, a p-value measures how incompatible observed data are with a specified null model, assuming the model and its assumptions are appropriate. It is not the probability that a hypothesis is true, and it does not quantify the size or practical importance of a difference. A p-value should be considered alongside an effect estimate, uncertainty interval, study design, and outcome definition. No p-value for the primary outcome is reported in the registry record, so no conclusion about statistical evidence can be drawn from a significance test.
The sample-size assumptions recorded for a planning illustration describe a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The illustration is based on the observed effect and considers the stated fraction of that effect. It is explicitly a planning illustration, not the trial’s own design justification. The registry record does not report a sample-size justification for the trial itself, nor does it report an observed effect to which the illustration can be linked. The illustration should not be interpreted as observed power or as evidence that the study was adequately sized.
In general, power is a design-stage probability of detecting an effect of a specified size under stated assumptions. It is not a measure of how likely a reported result is to be correct. Retrospective power calculations based on an observed estimate are especially difficult to interpret because they largely restate the estimate and its uncertainty. The planning illustration in the registry record is not a substitute for an outcome estimate with a confidence interval.
What do the design details allow?
The primary outcome is collected by questionnaire immediately after the procedure. In general, collecting responses at a consistent time can make the measurement occasion clearer, but it does not settle whether the question is valid, whether participants understood it consistently, or whether responses were complete. The actual questionnaire and its administration details are not reported in the registry record.
The two group descriptions concern smoke evacuation, while the primary endpoint concerns preference related to surgical lights. In general, a study may examine whether an experience in one aspect of care relates to responses about another, but an interpretation depends on the allocation process and the relationship between exposure and outcome. The record does not state how smoke evacuation was assigned or describe how light exposure, smoke, and sounds were measured. It therefore does not support a detailed causal account of the sensory factors behind any preference.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists three outcome measures, but the information available describes only the primary outcome concerning surgical lights. The other outcomes and their roles in the analysis are not reported in the registry record. It is therefore not possible to determine whether the study planned multiple confirmatory tests, how outcomes were prioritized, or whether any adjustment for multiple comparisons was planned. In general, when many outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase; an analysis plan can address how such findings should be interpreted. No such plan is reported.
The record also does not report how missing questionnaire responses were handled. It does not state whether participants who did not answer the primary question would be excluded, counted in a particular response category, or addressed through another method. In general, missing responses can affect a percentage if the likelihood of responding is related to preference. Without the number of completed questionnaires and the missing-data approach, the denominator and potential influence of nonresponse cannot be assessed.
Analysis populations are not described. The record does not specify whether analyses would include all enrolled participants, only participants who completed the procedure, or another defined group. It also does not state how departures from the assigned group or incomplete procedures would be handled. These are not reported in the registry record.
No interim analyses or statistical analysis plan are reported in the registry record. This is not evidence that such activities did or did not occur; it indicates that their details cannot be established from this record.
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 |
|---|---|---|---|
| Smoke Evacuation Group | 0 | 80 | 0.0% |
| Control Group | 0 | 80 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Smoke Evacuation Group | 0 of 80 |
| Control Group | 0 of 80 |
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 |
|---|---|
| Smoke Evacuation Group | 0 of 80 |
| Control Group | 0 of 80 |
The registry record lists two groups with 80 participants at risk in each. For the Smoke Evacuation Group, it records zero serious adverse events, zero other adverse events, and zero deaths. For the Control Group, it also records zero serious adverse events, zero other adverse events, and zero deaths. No top serious-event terms are listed.
These entries are counts in the registry record, not a complete description of how safety was monitored or how events were defined, collected, and attributed. The record does not provide event narratives, follow-up duration, or details about the completeness of event reporting. The zero counts should therefore be read narrowly: no events are recorded in these categories for the listed groups in this record. They do not establish that no symptoms or other experiences occurred, since the record’s categories and reporting scope may not capture every experience.
The safety entries do not answer the primary preference question. They also do not establish that the groups are comparable for safety interpretation, because allocation is not stated and the record notes that the arms are not a like-for-like control comparison. These counts describe the recorded adverse-event information only.
12. What the Result Does, and Does Not, Mean
The registry record is useful for identifying the study’s stated topic, group descriptions, primary outcome, questionnaire timing, enrollment, and recorded adverse-event counts. It indicates that the primary question concerns patient preference related to surgical lights after outpatient Mohs surgery, while the broader purpose includes surgical smoke and sounds. It also documents groups described in relation to smoke evacuation and no smoke evacuation.
What the record does not establish is the primary result. It reports no percentage of participants expressing a particular preference, no group difference, and no confidence interval or p-value. Consequently, it cannot show whether responses favored one lighting experience, whether responses differed between groups, or how precisely any such difference was estimated. The absence of a reported analysis is not evidence that the outcome was identical across groups.
The record also does not establish a causal effect of smoke evacuation on preference. Allocation is not stated, and the record cautions that the groups are not a like-for-like control comparison. Even if a comparison were available, differences could not be attributed to smoke evacuation without considering how participants entered the groups, what other aspects of the procedure differed, and how the outcome was measured.
In general, patient-reported preferences are informative about participants’ stated experiences, but they are distinct from measures of clinical effectiveness, technical performance, or long-term outcomes. The registry record does not provide enough information about the questionnaire to determine the exact meaning of its response categories. The findings, if reported elsewhere in a complete analysis, would need to be interpreted in light of that measurement detail, missing responses, and the study design. The record alone supports a description of the research question and available administrative details, not a conclusion about what participants preferred or what sensory conditions caused those preferences.
13. Why This Trial Matters Statistically
This study raises a statistical question that is easy to overlook: how should a subjective preference be defined and summarized when the research topic involves several sensory features of a procedure? A percentage can communicate the frequency of a response, but its meaning depends on the question asked, the response options, and the participants included in the denominator. Without those details and the actual results, the interpretation remains limited.
The study also highlights the importance of aligning the research question, comparison, and outcome. The broader purpose names surgical lights, smoke, and sounds; the group descriptions distinguish smoke evacuation from no smoke evacuation; and the primary outcome concerns preference related to lights. These elements may be relevant to one another, but the registry record does not explain the intended analytic relationship. Clear reporting would help readers understand whether the primary aim is to describe preferences, compare groups, or assess how a specific sensory exposure relates to a response.
Allocation is central to that interpretation. A comparison between groups can be descriptive, but a causal claim requires a design and analysis that address alternative explanations. The registry record does not state the allocation method and cautions that the groups are not a like-for-like control comparison. This makes transparent reporting of group formation especially important.
Finally, the record demonstrates why completed status alone is not equivalent to accessible results. It records enrollment and timing but does not report the primary outcome estimates or analysis. Without those results, readers cannot assess the size or precision of any preference pattern. The statistical importance of the study lies in the need for clear outcome definitions, transparent comparisons, and complete reporting, rather than in a conclusion that the registry record does not provide.
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 several trial-specific details unavailable. It does not report participant eligibility criteria, demographic or clinical characteristics, or the setting beyond outpatient Mohs surgery. Those omissions make it difficult to judge which patient groups the study population represents.
The questionnaire is described as anonymous and administered immediately after surgery, but its wording, response choices, validation, and scoring rules are not reported in the registry record. The record does not explain how a response was classified as a preference or how the percentage denominator was determined. It also does not state whether every participant completed every question.
The two group descriptions concern smoke evacuation, but allocation is not stated. The record explicitly cautions that the arms are not a like-for-like control comparison. It does not describe how smoke evacuation was implemented, whether surgical lights or sounds varied across procedures, or whether other procedural factors were recorded. This limits assessment of confounding and of how closely the group comparison matches the primary question about lights.
Although three outcome measures are listed, only the primary outcome is described in the available record. Definitions for the other outcomes, the analysis plan, handling of missing data, and analysis populations are not reported in the registry record. No primary outcome estimates or statistical analyses are recorded. The adverse-event counts are listed, but details of event definitions, collection, and follow-up are not available.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Impact of Sensory Stimuli on Patient Preferences During Outpatient Surgery — NCT02958826.
- Registry record last updated 2019-02-15; status last verified 2018-09.
- Results first posted 2019-02-15.
- 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
NCT02958826 is a completed study sponsored by the University of Missouri-Columbia, with an enrollment of 160. The registry record lists a start date of 2016-10 and a primary completion date of 2017-07-01. Its stated purpose is to examine how surgical lights, smoke, and sounds relate to satisfaction with outpatient Mohs surgery.
The listed intervention is an anonymous questionnaire. Group descriptions distinguish smoke evacuation from no smoke evacuation. The primary outcome concerns preference related to surgical lights, measured as a percentage of participants immediately after the procedure. The record lists three outcome measures but describes only the primary measure in the information available.
Outcome estimates, statistical analyses, allocation details, questionnaire specifications, and missing-data methods are not reported in the registry record. The adverse-event listing records zero serious events, zero other events, and zero deaths in each group, with 80 participants at risk per group. These details describe the registry entries but do not provide a primary outcome conclusion.