Evaluation of Potential Screening Tools for Metabolic Body Odor and Halitosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Potential Screening Tools for Metabolic Body Odor and Halitosis (NCT02692495), a registered phase not stated study. The primary outcome is Number of Test Results Outside the Normal Range.

2. Clinical Question

3. Trial Design

This is a completed retrospective cohort study, rather than a randomized trial. Its stated purpose was to assess whether gastrointestinal and nutritional diagnostic procedures might be useful as screening tools for metabolic body odor and halitosis. The brief description concerns generally healthy people who self-reported symptoms, had undergone diagnostic testing recommended by their physicians, and had not been diagnosed with a known medical condition. The registry record lists 16 participants.

The study separates participants into a Body Odor group and a Halitosis group. The first includes people reporting recurrent episodes of uncontrollable body odor, with or without halitosis. The second includes people with extra-oral halitosis who did not complain of body odors. These symptom-defined groups are not described as randomly assigned, and allocation is not stated. The registry record specifically cautions that the arms are not a like-for-like control comparison. Differences between them could reflect differences in who entered each symptom group as well as any differences in test results.

The record lists a start date of 2009-04 and primary completion in 2013-12, and gives the status as completed. It identifies Mebo Research, Inc. as sponsor. The primary outcome timeframe is described as four years. The stated outcome focuses on test results outside laboratory-specific reference ranges; the registry description does not give the detailed test list or report the results for the groups.

There are four outcome measures in the record, with one analysis listed. The secondary outcomes concern discriminative biomarkers, the number of results outside normal ranges in different malodor subgroups, and average daily added sugar intake inferred from self-reported dietary data. The analysis methods, group-specific outcome estimates, and any adjusted comparisons are not reported in the registry record. As a retrospective cohort, the study can describe patterns in the recorded testing and symptom groups, but the stated design does not assign a diagnostic procedure or establish a causal effect.

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

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 Number of Test Results Outside the Normal Range, measured over four years.

The primary endpoint is titled “Number of Test Results Outside the Normal Range.” The record lists participants as the unit and describes comparing laboratory-measured values with the reference range specific to Biolab Medical Unit. The investigators’ stated aim was to evaluate the strength of evidence for diagnostic accuracy of laboratory tests in diagnosing malodor syndromes. The outcome timeframe is four years.

An out-of-range result is a comparison between a measured value and a laboratory’s reference range. In general, counting such results can describe how often test values fall outside that range in a population or subgroup. It does not, by itself, show whether a test correctly identifies a clinical syndrome. Diagnostic accuracy typically requires comparing test classifications with an appropriate reference diagnosis and reporting measures of agreement or discrimination. Those estimates and the reference diagnosis used for such an assessment are not reported in the registry record.

The endpoint title refers to test results, while its listed unit is participants. The registry record does not clarify whether the reported measure would be a count of participants with one or more out-of-range results, a count of results attributed to participants, or another summary. No observed primary endpoint values, subgroup estimates, or uncertainty intervals are reported. Consequently, the endpoint’s purpose can be described, but its observed magnitude and precision cannot be interpreted from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a binary outcome type and describes the primary measure as a number of test results outside the normal range, with participants as the unit. It does not identify the statistical procedure used to analyze this outcome. The concepts below explain how such data and diagnostic evaluations are generally interpreted; they are not a description of an analysis method confirmed for this study.

What does an out-of-range result represent?

In general, a laboratory reference range provides a basis for classifying a measured value as within or outside that range. This classification is not automatically equivalent to a diagnosis. A value outside a reference range can be counted, but clinical interpretation depends on what the test measures, how the range was established, and how the result relates to a relevant diagnostic standard. The registry says the comparison would use reference ranges specific to Biolab Medical Unit. The test list, actual values, thresholds, and any clinical reference diagnosis are not reported in the registry record.

Counts can be summarized for groups, but the unit of analysis matters. A participant may have been tested on multiple measures; the endpoint title refers to test results, whereas the stated unit is participants. The registry record does not explain how multiple out-of-range results within the same participant would contribute to the primary measure. That ambiguity limits the ability to know exactly what an endpoint value would represent, even if a value were posted.

Why does the comparison group matter?

In general, a diagnostic test is assessed by comparing its result with a reference standard that identifies whether the condition of interest is present. Measures of diagnostic performance can then describe how test classifications correspond to that reference. A comparison of test patterns between symptom groups may be informative, but it is not necessarily a diagnostic-accuracy analysis. Here, the groups are defined by self-reported symptoms, and the record does not identify a separate unaffected control group or a reference diagnosis used to classify malodor syndromes.

The record cautions that the arms are not a like-for-like control comparison and says allocation is not stated. In an observational cohort, group differences can reflect participant characteristics, symptom definitions, test ordering, or other factors. General statistical adjustment can sometimes account for measured differences, but the registry does not report whether adjustment was planned or performed. Unmeasured differences would remain a concern even if measured factors were considered.

What would uncertainty estimates tell a reader?

In general, a confidence interval describes the range of values compatible with an estimate under the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, while neither interval alone establishes that a finding is clinically important or free of bias. No confidence intervals or other uncertainty estimates for the primary outcome are reported in the registry record. There is therefore no posted precision estimate to interpret.

For count outcomes, the appropriate analysis depends on how counts are generated, whether participants contribute repeated or multiple measurements, and how variable the counts are. General count-data methods may need to account for over-dispersion, meaning that observed variability exceeds what a simpler model assumes. This is a general statistical consideration, not a reported feature of this study. The registry record does not provide the distribution of test counts or identify a count model, binary model, or other procedure.

What do the planning assumptions mean?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not a description of the retrospective cohort’s original design. The registry record does not report the trial’s own sample-size justification or provide an observed effect estimate in the listed details. A planning illustration based on an observed effect should not be interpreted as observed power, and it does not establish that the study had adequate precision for its endpoints.

The general purpose of a sample-size calculation is to illustrate the amount of information a hypothetical design might need under specified assumptions. Such calculations depend on the assumed effect and analysis framework. They cannot replace reported estimates and uncertainty from the data actually analyzed. No sample-size justification or interim analysis plan is reported in the registry record.

How should multiple outcomes be considered?

When a study evaluates multiple outcomes or subgroups, the chance of obtaining at least one apparently notable result can increase if many tests are conducted. General approaches to multiplicity include defining a primary outcome in advance and adjusting inference across selected comparisons. The record lists four outcome measures and one analysis, but does not describe which statistical tests were conducted, whether any adjustment was used, or how secondary outcomes were interpreted. The number of listed analyses does not resolve those questions.

In summary, statistical interpretation would require the observed outcome values, a clear definition of the participant-level endpoint, the diagnostic reference used, the analysis method, and uncertainty estimates. These items are not reported in the registry record. General statistical principles can explain what would be needed to evaluate the study, but cannot supply its missing results or analysis details.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists four outcome measures: the primary measure concerning test results outside the normal range, and secondary measures concerning discriminative biomarkers, the number of out-of-range results in malodor subgroups, and average daily added sugar intake inferred from self-reported dietary data. It lists one analysis. The record does not explain whether that analysis covered all outcomes, whether additional comparisons were made, or whether any multiplicity adjustment was planned or used.

In general, assessing several endpoints or subgroups can increase the chance that at least one result appears notable by chance. A prespecified primary outcome and a clearly described strategy for secondary analyses help readers distinguish confirmatory questions from exploratory ones. The registry record does not report such a strategy, so the degree to which multiplicity was considered cannot be determined from the posted information.

Missing-data handling is not reported in the registry record. The record does not state how incomplete laboratory tests, unavailable dietary reports, or missing participant information would be treated. It also does not define analysis populations, such as which participants or measurements would be included for each outcome. Without those details, readers cannot assess whether the analyzed data represent all enrolled participants or whether missingness could have affected the summaries.

The registry lists enrollment of 16, but does not report outcome-specific denominators or the completeness of each measure. The absence of those details prevents assessment of how much information contributed to each analysis. It also prevents evaluation of whether exclusions or missing measurements could have influenced comparisons between the symptom-defined groups.

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.

The registry records serious adverse events, other adverse events, and deaths separately for the two symptom groups. In the Body Odor group, 12 participants are listed as at risk; the recorded counts are 0 serious adverse events, 0 other adverse events, and 0 deaths. In the Halitosis group, 4 participants are listed as at risk; the corresponding counts are also 0, 0, and 0.

These are observed registry counts, not estimates of risk over a specified follow-up period. The record does not describe the method or schedule used to collect adverse-event information, whether events were assessed for relation to a diagnostic procedure, or the completeness of safety reporting. The study is described as a retrospective evaluation of diagnostic procedures, not as a randomized treatment comparison. Accordingly, these counts should be read as the safety entries recorded for the groups, not as evidence that a procedure caused or prevented an event.

The record does not report additional detail about event definitions or severity beyond the serious and other categories. Zero recorded events means none are listed in these entries; it does not, by itself, establish that no unrecorded events occurred or characterize safety outside the recorded participants and period.

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

The record establishes that a completed retrospective cohort study was designed to examine whether gastrointestinal and nutritional diagnostic procedures might serve as screening tools for metabolic body odor and halitosis. It identifies symptom-defined groups, a primary outcome concerning out-of-range test results, and secondary questions about biomarkers, test results, and dietary sugar intake. It also records enrollment of 16 participants and the group-specific adverse-event counts.

The posted information does not report the observed primary outcome, group-specific test findings, diagnostic accuracy estimates, confidence intervals, or p-values. It therefore does not show how many results were outside reference ranges or how precisely the tests distinguished participants with different symptom descriptions. The intended comparison with a laboratory reference range is not itself a complete report of diagnostic performance against a clinical reference diagnosis.

The design also does not support a causal interpretation. The Body Odor and Halitosis groups are based on symptom descriptions, not random allocation, and the record says they are not a like-for-like control comparison. Any group differences, if reported elsewhere, would need to be interpreted in light of potential differences between participants and the observational nature of the study.

The safety entries list no serious adverse events, other adverse events, or deaths in either group. Those counts do not provide a full account of event collection or attribution. Nor do they substitute for the missing efficacy or diagnostic-performance results.

In general, evidence about screening performance requires clearly defined tests, a suitable reference standard, transparent analysis methods, and estimates with uncertainty. The registry record does not report enough result detail to make those assessments. Its completion status indicates the study is marked completed; it does not imply that the intended screening questions were answered with a particular result.

13. Why This Trial Matters Statistically

This study raises a statistical question that differs from a conventional treatment comparison: whether diagnostic measurements can help characterize or identify symptom-defined groups. Such a question depends not only on whether test values fall outside a reference range, but also on whether those classifications correspond to a relevant clinical condition. Distinguishing a laboratory reference range from a diagnostic reference standard is important when interpreting claims about screening or diagnostic accuracy.

The retrospective design is also statistically important. Participants were grouped according to reported symptoms, and allocation is not stated. Because the groups are not like-for-like controls, any contrast would be observational. Group differences could be related to how participants were selected, what tests they received, or other characteristics; the registry does not report an adjustment strategy. This limits what a comparison can establish, even if outcome estimates were available.

The study lists several outcome areas, including biomarkers, out-of-range test results, and self-reported dietary information. Each raises distinct questions about measurement and analysis. For example, laboratory results depend on the tests and reference ranges used, while dietary intake inferred from self-report may be affected by reporting and measurement uncertainty. The record does not report detailed methods or results for these outcomes, so their statistical contribution cannot be assessed.

Finally, the record illustrates why completed status and enrollment alone are insufficient for judging evidence. Interpretation requires actual outcome estimates, uncertainty, clear analysis populations, and an account of missing data and multiplicity. Those details are not reported in the registry record. The study’s stated question is relevant to evaluating potential screening tools, but the posted information does not establish how well any tool performed.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation for interpreting this record is that the outcome results are not reported in the registry information described. There are no primary endpoint values, group-specific test summaries, diagnostic accuracy measures, or uncertainty estimates. This prevents assessment of the magnitude and precision of any observed pattern.

The endpoint description leaves its participant-level calculation unclear. It names the number of test results outside the normal range and lists participants as the unit, but does not explain how multiple tests or multiple out-of-range values within a participant would be handled. The registry also says values would be compared with Biolab Medical Unit reference ranges, but does not identify the tests, ranges, or clinical reference diagnosis used to evaluate malodor syndromes.

The symptom groups are not randomized and are not described as equivalent control groups. One group can include participants with halitosis as well as body odor, while the other is described as extra-oral halitosis without complaints of body odor. The record does not report detailed baseline characteristics or an adjustment plan that would help assess comparability. Findings from such groups would be observational.

The registry does not report missing-data procedures, outcome-specific denominators, analysis populations, statistical methods, or a multiplicity strategy. The listed count of analyses does not provide those details. The record also does not report the study’s own sample-size justification or interim analysis plan. Safety counts are listed, but event collection methods, follow-up details, and attribution are not reported. These gaps limit interpretation of both the diagnostic aims and the recorded safety entries.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of Potential Screening Tools for Metabolic Body Odor and Halitosis — NCT02692495.
• Registry record last updated 2018-02-22; status last verified 2018-01.
• Results first posted 2018-01-24.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record identifies NCT02692495 as “Evaluation of Potential Screening Tools for Metabolic Body Odor and Halitosis,” sponsored by Mebo Research, Inc. It describes a completed retrospective cohort study with enrollment of 16 participants. The recorded study start is 2009-04, and primary completion is 2013-12.

The study groups are defined by self-reported body odor and halitosis symptoms. Its primary outcome concerns test results outside the normal range, compared with reference ranges specific to Biolab Medical Unit. Secondary outcomes concern biomarkers, out-of-range test results across malodor subgroups, and added sugar intake inferred from self-reported dietary data.

The posted registry information does not report the primary outcome values, diagnostic accuracy estimates, statistical analysis methods, confidence intervals, or p-values. It lists no serious adverse events, other adverse events, or deaths in either group. The record cautions that the arms are not a like-for-like control comparison.