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 Antimicrobial Efficacy of 2% CHG (Chlorhexidine Gluconate) (NCT02530541), a non-randomized phase 1, phase 2 study. The primary outcome is Log Reduction of Bacterial Flora on the Abdomen and Groin.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02530541 |
| Phase | Phase 1, Phase 2 |
| Condition | Healthy |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 33 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medline Industries |
| Results posted | Yes |
2. Clinical Question
The trial concerns preoperative skin preparation in healthy participants. It compares application of the CHG cloth for 1 min and 2 min with a marketed CHG comparator. The stated clinical question is whether these preparations differ in their measured reduction of normal bacterial flora on the abdomen and groin at 10 min, 6 hr and 8 hr.
Population
Healthy participants. The registry lists an enrollment of 33; arm-specific enrollment and the number analyzed for the primary outcome are not reported in the registry record.
Intervention
CHG cloth preoperative skin preparation, represented by arms labelled CHG 1 min and CHG 2 min. Their descriptions specify the corresponding application times.
Comparator
A marketed CHG preparation, listed as Comparator CHG. The record does not describe further details of the comparator procedure.
Primary question
How does mean log reduction of bacterial flora on the abdomen and groin vary across the listed preparations and assessment times? The registry also mentions determining 70% responder rates, but does not define a responder threshold.
The outcome is described as a mean continuous measure with standard deviation. That differs in form from a responder-rate question, which would classify participants according to a specified criterion. The registry does not explain how these descriptions relate, so the responder wording cannot be interpreted as a reported binary outcome. Nor does the record give outcome estimates that would answer the comparison question. The trial’s stated purpose and endpoint can be described, but the posted record does not establish the size or precision of any difference between preparations.
3. Trial Design
This is a completed pilot trial listed in Phase 1 and Phase 2. The registry records a non-randomized allocation, single masking and a parallel model, with enrollment of 33. The listed arms are CHG 1 min, CHG 2 min and Comparator CHG. The record gives the CHG application times and identifies the comparator as marketed CHG, but does not describe the allocation procedure, masking details, or the comparator’s application procedure.
The non-randomized allocation is important to interpretation. Random allocation is a general method for reducing systematic differences between treatment groups; without it, differences in participant characteristics or other aspects of care may be associated with the chosen preparation. The registry record does not report how participants were assigned, whether baseline characteristics were compared, or whether any adjustment was planned. The sponsor’s record identifies Medline Industries. The study start is listed as 2014-04, primary completion as 2014-07, and status as completed.
The posted design information does not make the arms a like-for-like randomized control comparison. In particular, the record does not establish that the groups were comparable before treatment. The reported enrollment is not broken down by arm, and the numbers contributing data at each assessment time are not reported in the registry record. The planned assessment times are 10 min, 6 hr and 8 hr; the record does not explain whether the same participants were measured at every time or how repeated measurements were handled.
The designation “pilot” signals the trial’s stated role, but the registry does not give a sample-size justification or describe the intended precision of estimates. A planned target, a rationale for enrollment, and any design assumptions beyond those listed for the separate planning illustration are not reported in the registry record. The design information therefore helps describe what was intended, but it does not substitute for numerical outcome results or a detailed statistical analysis plan.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: Participants were randomized to be treated with at least 2 treatments/ Arms (out of 3) at the same time for both groin and abdomen. Total numbers represent sites not the individual number of participants.
Overall Study
| Stage | CHG 1 Min Abdomen | CHG 2 Min Abdomen | Comparator CHG Abdomen | CHG 1 Min Groin | CHG 2 Min Groin | Comparator CHG Groin |
|---|---|---|---|---|---|---|
| STARTED | 21 | 23 | 22 | 21 | 20 | 19 |
| COMPLETED | 14 | 15 | 14 | 15 | 15 | 14 |
| NOT COMPLETED | 7 | 8 | 8 | 6 | 5 | 5 |
Analysis population for the primary outcome, as defined in the registry: Determine 70% responder rates
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: Participants received up to 2 treatments at the same time. The treatments included 2 different testing sites.
| Characteristic | Unit | CHG 1, CHG 2, Comparator CHG |
|---|---|---|
| Participants analysed | 33 | |
| Age, Customized: Age | years | 48 (19 to 79) |
| Sex: Female, Male: Female | Participants | 21 |
| Sex: Female, Male: Male | Participants | 12 |
| Region of Enrollment: United States | Sites exposed | 33 |
6. Primary Endpoint
The registry lists the primary outcome as Log Reduction of Bacterial Flora on the Abdomen and Groin, measured over 10 min, 6 hr and 8 hr.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Log10 Reductions |
| Endpoint classification | Continuous Endpoint |
The primary outcome is titled “Log Reduction of Bacterial Flora on the Abdomen and Groin.” It is described as a mean continuous measure, with standard deviation as the dispersion measure, assessed at 10 min, 6 hr and 8 hr. The stated purpose is to evaluate log reduction of normal flora at these timepoints.
In general, a log-transformed measure expresses changes on a logarithmic scale rather than as raw counts. A log-reduction endpoint is used to describe the extent to which bacterial flora decline following a preparation. The scale can be useful when the underlying counts vary over a wide range, because proportional changes can be easier to compare than raw differences. These are general properties of log-scale outcomes; the registry record does not describe the measurement procedure, the baseline calculation, or the laboratory methods used in this trial.
The mean summarizes the group’s central value, while the standard deviation describes how spread out individual measurements are around that mean. A mean alone would not show whether participants’ values were tightly clustered or widely dispersed. The registry identifies the type of summary but provides no numerical mean, standard deviation, or confidence interval for the endpoint.
The outcome description also says “Determine 70% responder rates.” A responder analysis ordinarily requires a defined threshold that classifies an individual result as meeting or not meeting a criterion. That threshold, and the relationship between this wording and the continuous mean outcome, are not reported in the registry record. Consequently, the primary endpoint can be identified, but the responder definition and the observed endpoint results cannot be evaluated from the posted record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a primary outcome and assessment times, but lists 0 analyses and gives no numerical outcome estimates. There is therefore no posted mean log reduction, standard deviation, treatment contrast, confidence interval or p-value to interpret. The record does not show whether the listed preparations differed at any assessment time, nor how precisely any estimate was measured. A claim about the size, direction or statistical significance of an outcome would go beyond the information recorded.
The endpoint is presented as a continuous mean, while the population description refers to determining 70% responder rates. These statements do not provide a usable responder definition: no threshold for response is reported. It is also unclear whether the stated responder objective was intended as an additional analysis, an interpretation of the continuous measure, or simply a description of the target population. The record does not resolve that ambiguity.
Even if numerical group summaries were available, the non-randomized allocation would limit a causal interpretation of group differences. In general, treatment groups in non-randomized studies can differ in ways that affect outcomes. The registry record does not report allocation details, baseline comparisons or a planned adjustment strategy. The arm descriptions identify the application times and marketed comparator, but do not establish that other aspects of preparation or measurement were comparable.
The primary outcome has three stated assessment times. Multiple assessments can raise questions about which comparison is primary, how the separate time-specific results are interpreted, and whether multiplicity is addressed. The registry record does not report a multiplicity procedure or identify a preferred timepoint among 10 min, 6 hr and 8 hr. It also does not state how repeated observations, if any, were modeled.
The adverse-event listing records 0 serious events and 0 other events for a combined group titled CHG 1 Min, CHG 2 Min, Comparator CHG, with 33 at risk in each listed category. This is a descriptive registry entry, not evidence that no events could occur. The record does not provide arm-specific safety counts, event definitions, or a follow-up description for safety. Deaths are not reported in the registry record.
Overall, the registry supports a description of the trial’s objective, design labels and recorded safety counts. It does not contain the numerical primary-outcome results needed to assess the observed effect or its uncertainty. The absence of analyses in the registry is not itself evidence of no effect, no difference, or no variability.
9. Statistical Methods Explained
The statistical information in the registry is limited. It classifies the primary measure as continuous and summarizes it as a mean with standard deviation, but lists no analyses. The following concepts are general explanations of how these methods are commonly interpreted; they are not a description of analyses confirmed to have been performed in this trial.
What does a mean describe?
A mean is a summary of the average measurement in a group. For a continuous endpoint such as log reduction, it can provide a concise description of the group’s overall level. It does not show the full distribution of individual measurements. In particular, similar means can arise when individual values are tightly grouped or when they vary considerably.
The standard deviation describes the spread of observations around a group mean. It is not the same as the uncertainty in the estimated mean. That uncertainty also depends on how many observations contribute and on the variability in the outcome. The registry identifies standard deviation as the dispersion measure but does not report its value or the number of observations analyzed at each timepoint. The precision of the primary-outcome mean therefore cannot be assessed from the registry record.
What would a confidence interval add?
In general, a confidence interval gives a range of values compatible with the data and the method used to calculate the interval. For a group difference, it can show both the direction and the precision of an estimate. A narrow interval indicates greater precision than a wide interval, while an interval that includes values on both sides of no difference may be compatible with multiple interpretations. These principles describe confidence intervals generally; no confidence interval for this trial’s primary endpoint is reported in the registry record.
A p-value, if reported, would address how compatible the observed data are with a specified null model under the assumptions of the test. It would not measure the size or clinical importance of a difference, and it would not establish that the null model is true. No p-value or test result is listed for the primary outcome.
Why does allocation matter?
Randomization is a general design method that assigns participants by chance, helping balance both measured and unmeasured characteristics on average. This trial is recorded as non-randomized. Consequently, any comparison could be influenced by differences between participants assigned to the preparations, as well as by the preparations themselves. Statistical adjustment can sometimes account for measured differences, but it cannot automatically remove the influence of unmeasured factors. The registry does not report an adjustment plan or enough information to determine whether adjustment was performed.
Masking can reduce some forms of bias when people involved in care, measurement or assessment do not know the assigned preparation. The registry labels the study single masked but does not say who was masked, how masking was maintained, or whether outcome assessors were masked. The effect of masking on measurement cannot therefore be evaluated from the recorded description.
Why can over-dispersion matter?
Over-dispersion is a general concern when observed variability is greater than a statistical model assumes. If a model understates variability, its standard errors may be too small and its confidence intervals too narrow. The concern is particularly relevant to outcomes modeled as counts or rates, although the specific endpoint is recorded as a continuous log-reduction mean. The registry does not report a model, diagnostics or any assessment of over-dispersion, so it is not possible to say whether it was relevant to the analysis undertaken.
How should the planning assumptions be read?
The registry describes a sample-size planning illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are assumptions for a planning illustration, not evidence about the study’s actual design rationale or achieved precision. The registry does not report a sample-size justification for the trial itself. Any planning sample sizes are illustrations, not observed power, and cannot replace estimates and uncertainty from the trial’s posted outcomes.
For a continuous outcome, a planning calculation generally depends on assumptions about the effect to detect and the variability of the measure. If those inputs are uncertain, the resulting planning estimate is uncertain too. The registry does not give the trial’s own assumptions or explain whether any planning illustration reflects the actual allocation across the three listed arms. No sample-size conclusion about the trial’s adequacy can be drawn from these planning assumptions alone.
What does the endpoint wording leave unclear?
The continuous mean outcome and the reference to 70% responder rates represent different types of summaries. A continuous analysis uses measured values, whereas a responder analysis requires a rule for classifying results. Such a rule should specify what level of outcome counts as a response and how the classification is applied. The registry does not report that rule, so the responder wording cannot be reproduced or evaluated. Nor does the record describe whether the analyses were intended to be at each timepoint, pooled across times, or adjusted for repeated measurements.
These general statistical concepts help distinguish an endpoint definition, a design assumption and an analysis result. The registry contains the first and some planning assumptions, but it does not contain primary-outcome estimates or an analysis description. Inference about effect size, precision or statistical significance is therefore not available from the posted record.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint is assessed at 10 min, 6 hr and 8 hr. Comparing preparations at multiple times can create a multiplicity issue: when several statistical tests are conducted, the chance of at least one apparently notable result can increase. General approaches include defining a primary timepoint in advance, adjusting for multiple comparisons, or treating the analyses as exploratory. Which approach was planned or used is not reported in the registry record.
The record identifies a continuous mean outcome and also mentions 70% responder rates, but does not define a responder threshold or clarify whether responder rates were a separate endpoint or analysis. The number and ordering of planned comparisons, and any procedure for controlling multiplicity across endpoints, arms or assessment times, are not reported. The registry lists 0 analyses, so it does not provide results that could be assessed for multiplicity or selective reporting.
Missing-data handling is also not reported in the registry record. The record does not state whether any primary-outcome measurements were missing, why they might have been missing, or how incomplete observations were treated. It does not describe an imputation method, a complete-case approach, or a sensitivity analysis. Absence of this information should not be read as evidence that there were no missing measurements.
The analysis population is not described. The registry does not state which participants were included in the primary-outcome analysis, whether all enrolled participants were analyzed, or how participants with unavailable measurements were handled. Arm-specific numbers analyzed at each timepoint are not reported. These omissions prevent assessment of how closely the analyzed population matches the enrolled population and whether exclusions could affect the comparisons.
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 |
|---|---|---|---|
| CHG 1 Min, CHG 2 Min, Comparator CHG | 0 | 33 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| CHG 1 Min, CHG 2 Min, Comparator CHG | 0 of 33 |
The registry lists a combined group titled CHG 1 Min, CHG 2 Min, Comparator CHG. For this group, 33 are recorded as at risk for serious events and 0 as affected; the other-event listing also records 33 at risk and 0 affected. These are the safety counts entered in the registry, not arm-specific estimates.
The combined listing does not show how the counts are distributed across the CHG 1 min, CHG 2 min and Comparator CHG arms. The registry record does not report event definitions, the safety observation period, or whether the at-risk counts correspond to all participants enrolled. Deaths are not reported in the registry record, and no top serious-event terms are listed.
In general, a zero count in a trial record means that no event was recorded in the stated group and category; it does not establish that the risk is absent. Safety counts should be interpreted in light of the population observed, the duration and completeness of follow-up, and how events were collected. Those details are not reported in the registry record, so the listed counts offer only a limited descriptive account.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed pilot trial evaluated preoperative CHG skin preparation in healthy participants. It identifies two CHG application-time arms and a marketed CHG comparator, and names mean log reduction of bacterial flora on the abdomen and groin as the primary outcome. The assessment times are 10 min, 6 hr and 8 hr. These details describe the question and design, not the observed comparative effect.
No numerical primary-outcome analyses are listed. As a result, the posted record does not show the mean log reduction in any arm, the difference between preparations, the variability of measurements, or the precision of a comparison. It cannot establish whether one preparation had a larger or smaller measured reduction, or whether any observed difference was statistically distinguishable from chance under a specified analysis.
The record also does not support a conclusion about responder rates. Although it refers to determining 70% responder rates, it gives no responder definition and no responder results. Without a threshold, the classification cannot be interpreted or independently assessed. The registry’s continuous-measure description does not resolve that ambiguity.
Because allocation was non-randomized, even a reported group difference would need cautious interpretation. Differences in participant characteristics or other conditions could contribute to a contrast between groups. The registry does not report allocation details or an analysis plan that would help assess such concerns. The single-masked designation is also not explained in enough detail to identify who was masked.
The safety entry records zero serious events and zero other events in a combined listing, but it does not provide arm-specific counts or enough follow-up information to characterize safety comparatively. These entries do not establish that the preparations are free of risk.
In short, the record describes a pilot comparison and its intended outcome, but not numerical efficacy or safety results sufficient to judge the size, direction or precision of differences. It should not be read as evidence for either benefit or lack of benefit.
13. Why This Trial Matters Statistically
This trial is statistically notable as a pilot comparison with a continuous microbiological endpoint, multiple assessment times and non-randomized allocation. Each feature affects what can be learned from results and how cautiously comparisons should be interpreted. The registry record makes these design features visible, while leaving important analysis details unavailable.
A mean log-reduction outcome can summarize changes in bacterial flora on a scale designed to express reductions. Reporting the mean together with a measure of spread would help readers understand both the average response and variability across participants. Confidence intervals around comparisons would add information about precision. The registry identifies the mean and standard deviation as the intended summaries but lists no analyses, so those statistical questions remain unanswered.
The timepoints—10 min, 6 hr and 8 hr—also matter because effects may be described at different stages after preparation. General statistical practice calls for clarity about which assessment is primary and how multiple time-specific comparisons are handled. Neither a preferred timepoint nor a multiplicity plan is reported in the registry record. The reference to 70% responder rates adds another interpretive issue because the threshold is not given.
Non-randomized allocation makes the comparison more vulnerable to differences between groups that are unrelated to the preparation. This does not make the trial’s observations meaningless, but it affects how strongly a group contrast can be attributed to the intervention. The registry does not report enough detail about assignment, baseline characteristics or adjustment to assess this concern.
Finally, a pilot trial’s value depends on transparent reporting of estimates and uncertainty, not merely on stating an objective. Here, the record identifies the intended comparison and endpoint, but gives no numerical outcome analyses. The statistical importance lies partly in distinguishing a clearly stated research question from an answer 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 identifies a non-randomized design, so the listed arms cannot be assumed to have been comparable at the outset. Details of how participants entered or were assigned to each arm are not reported in the registry record. Baseline characteristics and any adjustment for group differences are also not reported, limiting assessment of potential confounding.
The record gives an overall enrollment of 33 but does not break enrollment down by arm or report the number analyzed at each assessment time. It does not explain whether the same participants contributed measurements at 10 min, 6 hr and 8 hr. The measurement procedure, baseline definition for log reduction and laboratory methods are not described in the registry record.
Although the outcome is described as a mean with standard deviation, the registry lists 0 analyses and no numerical primary-outcome estimates. This prevents assessment of effect direction, magnitude, variability and precision. The additional reference to 70% responder rates is not accompanied by a responder threshold or results. A planned statistical analysis, including treatment of repeated assessments, is not reported.
The record does not describe who was masked under the single-masked designation. It also does not report how missing measurements, analysis populations or multiplicity were handled. These are material uncertainties for interpreting a comparison across arms and timepoints.
Safety information is listed for a combined group rather than separately by arm. Event definitions and safety follow-up are not reported, and deaths are not reported in the registry record. The listed zero counts therefore provide limited information for comparing safety between preparations. The planning illustration assumptions do not constitute a reported sample-size justification for this trial, which is not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Antimicrobial Efficacy of 2% CHG (Chlorhexidine Gluconate) — NCT02530541.
- Registry record last updated 2021-04-30; status last verified 2020-09.
- Results first posted 2021-04-30.
- 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 a completed pilot trial of preoperative CHG skin preparation in healthy participants. It lists non-randomized allocation, single masking and a parallel model, with enrollment of 33. The arms are CHG 1 min, CHG 2 min and Comparator CHG, identified as marketed CHG. The sponsor is Medline Industries; the recorded start is 2014-04 and primary completion is 2014-07.
The primary outcome is mean log reduction of bacterial flora on the abdomen and groin, with standard deviation as the stated dispersion measure and assessments at 10 min, 6 hr and 8 hr. The record also mentions 70% responder rates but does not define response. It lists 0 analyses, so numerical primary-outcome results and their precision are not reported in the registry record.
Safety entries record 0 serious events and 0 other events in a combined group; arm-specific safety results are not reported. Overall, the record documents the trial’s objective and design but does not provide outcome analyses sufficient to assess comparative effects.