Bacteria in Atherosclerotic Plaques and Adverse Events: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bacteria in Atherosclerotic Plaques and Adverse Events (NCT06935279), a registered phase not stated study. The primary outcome is Analysis of Bacterial Types in Plaques.

2. Clinical Question

3. Trial Design

This is a prospective, multicenter cohort study conducted in western China. The registry lists an enrollment of 200 and a status of completed. The recorded study start is 2024-01-01 and the primary completion date is 2025-07-31. Tang-Du Hospital is the sponsor and lead institution, with other participating hospitals described in the registry. The record does not state that participants were randomly assigned to groups.

The study population consists of patients aged 18 to 90 years undergoing carotid endarterectomy. Participants were to provide informed consent and meet inclusion criteria without meeting exclusion criteria. The registry describes multidisciplinary assessments, including neurological, neuropsychological, psychiatric, endocrine, and hematological assessments. Bacterial species identification was performed using 16S rDNA sequencing, with further validation by transmission electron microscopy.

Carotid endarterectomy is the listed procedure. The study description says patients underwent routine surgical treatment and follow-up visits as recommended by physicians, with clinical practice data recorded. The primary outcome timeframe runs from enrollment to the end of treatment at 90 days. This cohort structure can describe plaque bacteria and clinical observations, but it does not establish a randomized comparison of treatments. The registry record does not report the criteria separating the PPG and GPG groups in its adverse-event listing, nor does it describe a comparison plan between them.

The record does not report a detailed statistical analysis plan, allocation procedures, or a sample-size justification for the cohort. Although the study status is completed, that status alone does not indicate that outcome analyses or numerical primary results have been posted.

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: A total of 353 research candidates were enrolled in this study. Among them, 98 individuals were excluded due to ineligibility, and 55 declined participation. Ultimately, 200 participants who met the inclusion criteria were enrolled. All enrolled subjects had complete follow-up records.

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 Analysis of Bacterial Types in Plaques, measured over From enrollment to the end of treatment at 90 days..

The primary outcome is titled Analysis of Bacterial Types in Plaques. It concerns the relative abundance of bacterial types in plaque samples, expressed as a percentage, and is specified as a continuous measure summarized by a mean and standard deviation. Relative abundance is defined as the number of sequences for a particular operational taxonomic unit (OTU) divided by the total effective sequences in the sample, multiplied by 100%.

This measure describes the share of sequenced material attributed to a particular OTU within a sample. As a general statistical distinction, relative abundance is not the same as an absolute quantity of bacteria: a percentage can change when the composition of the sample changes, even if an absolute bacterial amount is not measured. The registry describes using the relative abundance of bacteria associated with poor prognosis as an indicator of expected prognosis. That description is a proposed interpretation of the measure, not a reported clinical finding.

The timeframe is from enrollment to the end of treatment at 90 days. The registry record does not report the observed mean, standard deviation, sample-level distributions, or the results of comparisons among disease types. It therefore does not establish how abundant any bacterial type was in the enrolled cohort or how precisely any estimated mean was measured.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry specifies a continuous primary measure: relative bacterial abundance in plaque samples, expressed as a percentage and described using a mean and standard deviation. It also describes 16S rDNA sequencing for bacterial identification and transmission electron microscopy for further validation. The record does not report the details of the statistical analyses actually performed.

What does relative abundance measure?

Relative abundance is the proportion of effective sequences assigned to a particular OTU within a sample, expressed as a percentage. The numerator is the sequence count for that OTU, and the denominator is the total effective sequences for that sample. This is a compositional measurement: the values for different bacterial types are related because they represent parts of the same total. As a general statistical point, a change in one component’s share can reflect changes in other components or in the total composition, not necessarily a change in the absolute amount of that organism. The registry does not report absolute bacterial quantities.

The record says higher relative abundance of bacteria associated with poor prognosis is expected to correspond to worse prognosis. That is a stated expectation, not a demonstrated relationship. Assessing such a relationship would require outcome data and an analysis linking bacterial measurements to clinical outcomes; those results are not reported in the registry record.

Why report a mean and standard deviation?

For a continuous measurement, the mean describes the central value across observed samples. The standard deviation describes how dispersed individual measurements are around that mean. These quantities answer different questions: the mean characterizes the average abundance, while the standard deviation characterizes variation among measurements. The standard deviation is not the uncertainty of the mean. A confidence interval, if reported, would address estimation uncertainty, but the registry record does not report one for the primary outcome.

Relative abundance is bounded as a percentage and may have a distribution that is skewed or concentrated near its boundaries. As a general consideration, a mean and standard deviation can be less informative about the shape of such data than a distributional summary or plot. The record does not report the observed distribution, transformations, or any method for handling unusual values, so it is not possible to assess whether the selected summary adequately represents the observed data.

What can cohort comparisons establish?

A prospective cohort records exposures and outcomes over follow-up, but it does not by itself remove differences between groups. The registry does not report randomized allocation, and it does not provide definitions for the PPG and GPG adverse-event groups. If any comparisons of bacterial abundance or clinical outcomes were made, the selected groups, adjustment variables, and analysis methods are not reported in the registry record. Associations in an observational cohort can be influenced by differences in participant characteristics, clinical care, and other factors; they should not automatically be interpreted as causal effects.

The study description mentions a multidisciplinary assessment and follow-up through the end of treatment at 90 days. It does not report how repeated measurements, if any, were analyzed or whether timing differed among participants. It also does not report a model for relating bacterial measurements to clinical events. Those analysis details matter because they determine which data contribute to an estimate and how uncertainty is quantified.

How should planning illustrations be read?

The stated planning assumptions describe illustrations based on an observed effect, not the study’s own design justification. They specify a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. For time-to-event illustrations, the stated quantity is the total number of events; other illustrations use participants per arm. These assumptions are not evidence that the cohort had a particular level of power. Sample-size illustrations are planning aids, not observed power, and the registry record does not report a sample-size justification for this study.

The registry record reports no primary analysis estimates, confidence intervals, hypothesis tests, or analysis populations. It is therefore not possible to judge whether the intended summaries were calculated, whether assumptions were checked, or how precise any result might be. The methods distinguish the registered measurement from the unreported statistical analysis.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("PPG Group", "GPG Group")
n   <- c(20, 180)
m   <- c(2.2, 0.58)
sp  <- c(8.05, 3.21)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  PPG Group  20  2.200  8.050  -1.568  5.968
CARM  GPG Group  180  0.580  3.210  0.108  1.052

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome concerning bacterial types in plaques, but it does not report the full set of planned comparisons, hypotheses, or secondary outcomes included in the statistical analysis. It is therefore not possible to assess whether multiple bacterial types, disease categories, or clinical outcomes were tested, or whether any adjustment for multiple comparisons was planned or applied. The analysis plan is not reported in the registry record.

The registry describes a cohort enrollment of 200, but it does not report how many participants contributed primary outcome measurements or whether any plaque samples were unavailable or excluded. Missing-data rules, imputation methods, and sensitivity analyses are not reported in the registry record. The record also does not state how incomplete follow-up, unusable sequence data, or missing clinical assessments were handled.

The analysis population is not reported in the registry record. It is not stated whether the primary outcome would include all enrolled participants, only those with usable plaque sequencing, or another defined population. The registry does not report participant flow or reasons for exclusion from analyses.

These omissions limit interpretation because exclusions and missing measurements can affect which participants are represented by an estimate. When multiple bacterial types or outcome definitions are considered, the chance of highlighting an apparently notable result can also depend on how many analyses were conducted. Without the analysis plan and results, neither issue can be evaluated. The reported study status of completed does not resolve these questions.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: cerebral infarction (80.0%).

The registry’s serious adverse-event listing is descriptive. In PPG, 16 participants are listed as affected by serious events among 20 at risk; 0 are listed as affected by other events among 20 at risk, and 4 deaths are recorded. In GPG, 0 participants are listed as affected by serious events among 180 at risk; 0 are listed as affected by other events among 180 at risk, and 0 deaths are recorded. These figures should be read as registry counts, not as a controlled estimate of risk.

The registry also lists cerebral infarction as a top serious term, with 80.0%. The denominator and calculation basis for that percentage are not reported in the registry record. The record does not describe the definitions of PPG and GPG, event ascertainment or adjudication, the duration of safety follow-up, or whether event counts cover the same observation period in both groups.

Because the group definitions and comparability are not reported, the listed counts do not establish that group membership or the procedure caused an event. They also cannot be interpreted as a randomized safety comparison. The counts should not be combined with assumptions about the groups or used to infer an unreported rate.

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

This registry record describes a prospective, multicenter cohort of patients undergoing carotid endarterectomy, a plaque bacterial measurement, and follow-up through the end of treatment at 90 days. It identifies relative abundance as the primary outcome and describes sequencing and validation methods. It also records serious adverse-event information under the PPG and GPG labels.

What the record does not establish is a numerical result for the primary outcome. It does not report the mean relative abundance, standard deviation, or a statistical estimate connecting bacterial types to disease categories or prognosis. Accordingly, the registry does not show whether any particular bacterial type was common, whether abundance differed among patients, or whether a measured bacterial feature predicted a clinical outcome.

The adverse-event counts also do not establish a causal comparison. The registry record does not explain the group labels, report random allocation, or describe adjustment for differences between groups. Event counts without that context cannot isolate the effect of a procedure or a bacterial characteristic. The reported 80.0% for cerebral infarction is not accompanied by a reported denominator or calculation basis.

In general, the difference between a study objective and a result is important: an objective states what investigators intend to examine, while an estimate and its uncertainty are needed to judge what the observed data support. Here, the registry gives the objective and measurement definition but not the primary outcome estimates or their uncertainty. The completed status does not fill that gap.

The appropriate interpretation is therefore limited to the study structure, measurement plan, and descriptive event information recorded. Evidence about associations, precision, and clinical implications is not reported in the registry record. No conclusion about whether bacteria in plaques are associated with prognosis can be drawn from the listed endpoint description alone.

14. Why This Trial Matters Statistically

This study is statistically relevant because it applies sequencing-based bacterial measurement to plaque specimens in a prospective cohort and frames the measurement as relative abundance. That framing calls attention to a key distinction: a percentage describes composition, not an absolute bacterial quantity. As a general statistical issue, compositional measurements require careful interpretation because the share assigned to one component depends on the rest of the measured composition.

The planned use of mean and standard deviation gives readers a familiar summary of a continuous measure, but these summaries alone do not show the full distribution or the uncertainty around an estimate. For an outcome expressed as a percentage, distributional shape and the relationship among components can matter. The registry record does not report enough numerical results to examine these features.

The cohort design also matters. Prospective observation can document measurements and follow-up over time, but the absence of reported random allocation means that group comparisons, if undertaken, would need to be interpreted with attention to confounding and selection. The PPG and GPG labels in the safety listing are not defined in the registry record, so their counts cannot be treated as a like-for-like comparison.

Finally, the registry illustrates why study completion and result reporting are distinct. The record identifies the research question, outcome definition, and safety counts, yet does not provide primary estimates, confidence intervals, or a documented statistical analysis. Without those elements, readers cannot evaluate effect magnitude, precision, or the robustness of any association. The methodological interest lies in the question and measurement approach; the registry record does not report results sufficient to answer the question statistically.

15. Limitations

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

The registry record does not report numerical results for the primary outcome, including the mean and standard deviation of relative bacterial abundance. It also does not report confidence intervals, hypothesis tests, or analyses linking the primary measure with clinical outcomes. This prevents assessment of the magnitude and precision of any association.

The record does not define the PPG and GPG groups or state whether they represent prespecified cohort categories. It reports no randomized allocation, and does not describe an adjustment strategy for group comparisons. Consequently, the event counts cannot support a causal interpretation or a like-for-like comparison.

The record describes relative abundance based on sequencing, but does not report absolute bacterial measurements or detailed information about sample processing and quality criteria. Relative percentages represent composition and may not correspond to absolute bacterial quantities. The distribution of the primary measure and how it was summarized are not reported beyond the planned mean and standard deviation.

Participant flow, outcome-specific analysis populations, missing-data handling, and reasons for any exclusions are not reported in the registry record. Nor does the record provide a detailed statistical plan, including planned comparisons or methods addressing multiplicity. These omissions make it difficult to assess selection, completeness, and the risk of selective emphasis among analyses.

The registry describes the study as completed, but the primary completion date and status do not establish that every planned analysis is available. The listed serious adverse-event data also lack reported details about event ascertainment, follow-up duration, and the denominator for the cerebral infarction percentage. These limitations are specific to the information recorded and restrict interpretation of both the endpoint and safety information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Bacteria in Atherosclerotic Plaques and Adverse Events — NCT06935279.
• Registry record last updated 2026-03-24; status last verified 2026-03.
• Results first posted 2026-03-24.
• 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.

19. Record Summary

NCT06935279 is a completed prospective, multicenter cohort study sponsored by Tang-Du Hospital. It enrolled patients aged 18 to 90 years undergoing carotid endarterectomy, with an enrollment listed as 200. The recorded study dates are 2024-01-01 and 2025-07-31.

The primary outcome is relative abundance of bacterial types in plaque samples, expressed as a percentage and described using a mean and standard deviation. The registry describes 16S rDNA sequencing and validation by transmission electron microscopy, with follow-up through the end of treatment at 90 days.

Numerical primary outcome results and the statistical analysis are not reported in the registry record. The adverse-event listing gives descriptive counts for PPG and GPG, but the group definitions and comparison methods are not reported.