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 Aerosolized Antibiotics in the Treatment of Ventilator Associated Pneumonia (NCT02478710), a randomized phase 4 study. The primary outcome is Recurrence of Pneumonia.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02478710 |
| Phase | Phase 4 |
| Condition | Pneumonia, Ventilator-Associated |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 16 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Wright State University |
| Results posted | Yes |
2. Clinical Question
Population
People with ventilator-associated pneumonia were the population of interest. The registry record describes a pilot study and reports enrollment of 16 participants. It does not report further participant characteristics or the number who contributed data to the primary outcome.
Intervention
The intervention was aerosolized tobramycin or vancomycin, used in conjunction with intravenous antibiotics according to the study summary. The intervention description specifies aerosolized tobramycin 300 mg diluted in 5 mL 0.9% normal saline q.12h and aerosolized vancomycin 125 mg diluted in 5 mL 0.9% normal saline q.8h.
Comparator
The comparator was aerosolized placebo alongside intravenous antibiotics. The placebo description specifies placebo tobramycin 0.5 mL 0.9% normal saline q.12h and placebo vancomycin 0.5 mL 0.9% normal saline q.8h.
Primary question
The primary question was whether pneumonia recurred after treatment, assessed using a second bronchoalveolar lavage (BAL) during the stated 9-21 days after initiating antibiotic therapy. Recurrence was defined by at least one bacterial species growing above the specified concentration threshold. The registry record states that data for this outcome were not collected.
In practical terms, the trial was set up to compare adding aerosolized antibiotic treatment with using an aerosolized placebo, with intravenous antibiotics described as part of the treatment context. The primary endpoint concerned evidence of recurrent pneumonia in a later BAL sample, not simply whether pneumonia was present at the initial assessment. The registry record does not report an observed recurrence comparison, so the clinical question remains unanswered by the posted primary-outcome data.
3. Trial Design
This was a phase 4, randomized, triple-masked, parallel-group pilot study sponsored by Wright State University. The registry lists enrollment of 16 participants and a terminated status. The recorded study start was 2015-06, and the primary completion date was 2017-02. These administrative details describe the registered study; they do not establish how many participants completed treatment or contributed information to any particular outcome.
Participants were assigned to one of two aerosol-treatment groups: aerosolized placebo or aerosolized tobramycin or vancomycin. The study summary frames the comparison as aerosolized antibiotics alongside intravenous antibiotics versus intravenous antibiotics alone, with aerosolized placebo serving as the control. The record gives dosing descriptions for the aerosolized treatments. It does not explain the decision process for choosing between tobramycin and vancomycin for an individual participant.
Randomization is intended to make treatment groups comparable, on average, with respect to factors that could influence outcomes. Masking is intended to reduce the influence of treatment knowledge on care, assessment, or reporting. These are general purposes of the design features; the registry record does not identify which groups of people were masked, describe the randomization procedure, or report whether masking was maintained.
The record lists nine outcome measures, including the primary recurrence endpoint and secondary outcomes such as ventilator-free days, ICU-free days in 28 days, 28-day ICU mortality, renal insufficiency, organ dysfunction, resistant organisms, and antibiotic days. It lists no analyses. The study's terminated status and pilot designation are important context, but the registry record does not state why the study was terminated or describe its sample-size justification.
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 | Aerosolized Placebo | Aerosolized Tobramycin or Vancomycin |
|---|---|---|
| STARTED | 10 | 6 |
| COMPLETED | 10 | 6 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Data was not collected.
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 | Aerosolized Placebo | Aerosolized Tobramycin or Vancomycin | Total |
|---|---|---|---|---|
| Participants analysed | 10 | 6 | 16 | |
| Age, Customized: Age – Under 18 | Participants | 0 | 0 | 0 |
| Age, Customized: Age – Over 18 | Participants | 10 | 6 | 16 |
| Sex: Female, Male: Female | Participants | 2 | 3 | 5 |
| Sex: Female, Male: Male | Participants | 8 | 3 | 11 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Patients who required ≥48 hours of mechanical ventilation | Participants | 10 | 6 | 16 |
| Patients who had a Clinical Pulmonary Infection Score ≥6. | Participants | 10 | 6 | 16 |
6. Primary Endpoint
The registry lists the primary outcome as Recurrence of Pneumonia, measured over 9-21 days after initiating antibiotic therapy.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was recurrence of pneumonia, assessed using a second bronchoalveolar lavage (BAL) during 9-21 days after initiating antibiotic therapy. The registry definition required at least one bacterial species growing at concentrations of >10 to the fourth power organisms in that sample. The endpoint therefore focuses on microbiological evidence of recurrence in a later BAL, rather than a broad clinical judgment alone.
In general, a defined endpoint helps make the question measurable and gives the treatment groups a common outcome to compare. A culture-based recurrence measure can capture whether specified bacteria are detected at the stated concentration threshold. At the same time, the interpretation applies to this particular operational definition; it should not automatically be treated as interchangeable with every possible clinical definition of pneumonia recurrence.
The registry record says, “Data was not collected” for the primary outcome population. Consequently, it reports no primary-outcome event counts, group comparison, effect estimate, or uncertainty interval. The endpoint was specified, but its results cannot be evaluated from the posted record. The calculated results displays should therefore be read in light of that missing primary-outcome information rather than as evidence that recurrence differed between groups.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the registry identifies recurrence of pneumonia as the primary outcome but states that data were not collected. There is therefore no posted primary-outcome estimate to interpret. The record does not give recurrence counts, a difference between groups, a confidence interval, or a p-value for this endpoint. It is not possible to determine from these primary-outcome data whether the groups differed, or how precisely any difference might have been estimated.
The trial enrolled 16 participants and was randomized, but enrollment alone does not establish how many participants were included in an outcome analysis. The record lists no analyses. It also does not report reasons for the missing primary-outcome data or explain whether the lack of collection was planned, related to termination, or due to another circumstance. Those explanations should not be inferred.
The serious adverse event summaries are separate from the primary endpoint. For the aerosolized placebo group, the registry reports 10 at risk and 1 affected by a serious event; for the aerosolized tobramycin or vancomycin group, it reports 6 at risk and 0 affected. Both groups have 0 other events and 0 deaths in the posted figures. These small denominators describe the safety data captured in the record, not an adequately powered comparison of safety. The displayed serious-event summary also includes “Serious” at 10.0%. Counts and the summary percentage should be read as registry reporting, not as proof of a treatment-related difference.
General statistical interpretation depends on both the observed estimate and its uncertainty. A confidence interval, when reported, describes a range of values compatible with the data under the analysis assumptions; it is not a guarantee that the true effect lies within that range. Here, the registry does not report a primary-outcome estimate or interval, so neither the magnitude nor the precision of a recurrence comparison can be assessed.
The secondary outcomes listed in the record indicate other questions the study sought to address, including time free of ventilation or ICU care, mortality, renal insufficiency, organ dysfunction, resistant organisms, and antibiotic use. The record does not report outcome-specific analyses for these measures. The list of intended outcomes should not be mistaken for evidence of results. Overall, the posted record documents a randomized pilot study with a defined primary endpoint, but does not provide the primary-outcome observations needed to answer the recurrence question.
9. Statistical Methods Explained
The statistical methods that can be described from this record are limited. It identifies a randomized, triple-masked, parallel-group study and a primary recurrence endpoint, but lists no analyses. The registry record does not report the statistical analysis plan, the method used to generate the random sequence, the masking roles, or how outcome data were to be analyzed. The explanations below are general statistical context, not claims about methods used in this trial.
What does randomization contribute?
In general, randomization assigns participants to groups using a chance-based process. It can reduce systematic differences between groups at the time of assignment, including differences that are not measured. It does not ensure that small groups will be balanced on every characteristic. Nor does randomization by itself address missing outcomes, deviations from assigned treatment, or uncertainty from a small amount of data. The record says the study was randomized but does not describe the actual procedure or report baseline characteristics by group.
What does masking contribute?
In general, masking can reduce the chance that knowledge of assignment influences treatment delivery, outcome assessment, or participant-reported information. The record labels the study triple-masked, but does not say which people were masked or how masking was implemented. The label alone does not establish that every source of bias was prevented. In particular, it does not supply information about the reliability of the BAL assessment or whether assessors could infer group assignment.
How should a recurrence endpoint be analyzed?
As general context, a binary endpoint such as recurrence can be summarized by the number of participants meeting the definition in each group, with an effect estimate comparing those groups. A confidence interval would communicate uncertainty around that estimate. A p-value, if reported, would summarize how compatible the data are with a specified null hypothesis under the chosen statistical model; it would not describe the size or clinical importance of an effect. The registry record supplies none of these primary-outcome results. Moreover, because it says the primary outcome data were not collected, no comparison can be reconstructed from the posted record.
The endpoint definition has several elements that matter for interpretation: a second BAL, the stated interval of 9-21 days after initiating antibiotic therapy, and bacterial growth above the specified threshold. In general, consistent timing and measurement rules help make outcome classification reproducible. But statistical analysis also depends on knowing who was assessed, how missing samples were handled, and whether assessment timing varied. Those details are not reported in the registry record.
What can a small pilot study establish?
In general, pilot studies can help assess whether study procedures are workable and can generate preliminary estimates for later research. Estimates from a small study may be imprecise, especially when outcomes are uncommon or when few participants contribute data. A lack of a statistically clear difference would not, by itself, demonstrate equivalence; evidence of equivalence requires an appropriate design and analysis. This general point does not imply any particular finding in this study, since its primary outcome was not collected in the posted record.
The record characterizes its sample-size figures as planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; it also distinguishes participant counts per arm from total events for time-to-event calculations. Such illustrations are not observed power and are not evidence about the study's original design. The registry record does not report the trial's own sample-size justification. The actual planning outputs and a usable primary-outcome effect estimate are not reported in the registry record, so no numerical planning interpretation can be made.
Why does over-dispersion matter in general?
Over-dispersion occurs when observed variability is greater than a statistical model assumes. When it is ignored, uncertainty can be understated, making intervals too narrow and tests too optimistic. It is relevant to some outcome types and models, but the registry record does not describe a model for this trial or report an over-dispersion assessment. There is therefore no basis for saying that over-dispersion was present or that a particular adjustment was used.
Finally, an analysis population specifies which participants contribute to an estimate—for example, all randomized participants or only those with observed outcome data. Different choices can answer different questions and can be vulnerable to different biases. The registry record does not report an analysis population for the primary endpoint. Given the explicit statement that primary-outcome data were not collected, the posted record cannot establish what analysis population, if any, was used for that outcome.
10. Multiplicity, Missing Data and Analysis Populations
The record lists a primary outcome and multiple secondary outcomes. Considering many endpoints can raise a general statistical issue called multiplicity: the more separate hypotheses examined, the greater the chance that at least one result appears noteworthy by chance if each is assessed without adjustment. This is a general concern, not a statement that the trial made multiple statistical tests. The registry record lists no analyses and does not report a multiplicity strategy, such as an adjustment, a hierarchy of tests, or a distinction between confirmatory and exploratory analyses.
Missing data are especially central because the primary outcome population is described as “Data was not collected.” The registry record does not report the reason, extent, or timing of missingness beyond that statement. It also does not say whether the endpoint was unavailable for every participant, whether collection stopped at a particular point, or whether any imputation or sensitivity analysis was performed. Those details are not reported in the registry record.
In general, missing outcome data can undermine a group comparison if the availability of data is related to treatment assignment, prognosis, or the outcome itself. Statistical approaches to missingness depend on why data are absent and on the assumptions used. A method cannot recover information without assumptions, and a sensitivity analysis can show how conclusions might change under different assumptions. No such analysis is reported, and the stated absence of primary-outcome data means there is no posted recurrence comparison on which to base one.
The registry record also does not identify the analysis population for the secondary outcomes or explain how participants with incomplete follow-up were handled. It lists nine outcome measures, but an outcome list is not an analysis plan. Consequently, readers should not infer which outcomes were tested, whether any adjustment was applied, or how missing observations were treated.
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 |
|---|---|---|---|
| Aerosolized Placebo | 1 | 10 | 10.0% |
| Aerosolized Tobramycin or Vancomycin | 0 | 6 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Aerosolized Placebo | 0 of 10 |
| Aerosolized Tobramycin or Vancomycin | 0 of 6 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Aerosolized Placebo | 0 of 10 |
| Aerosolized Tobramycin or Vancomycin | 0 of 6 |
Most frequent serious adverse event terms
| Event term | Organ system | Aerosolized Placebo | Aerosolized Tobramycin or Vancomycin |
|---|---|---|---|
| Serious | Nervous system disorders | 1 of 10 | 0 of 6 |
Serious events with the highest arm-level rate: serious (10.0%).
The registry reports serious adverse event figures separately for the two aerosol-treatment groups. In the aerosolized placebo group, 10 participants were listed as at risk and 1 as affected by a serious event. In the aerosolized tobramycin or vancomycin group, 6 were listed as at risk and 0 as affected. The posted figures list 0 other events and 0 deaths in each group. The record's serious-event summary also displays “Serious” at 10.0%.
These are descriptive counts from a small pilot study. The groups have different numbers listed at risk, and the registry record does not provide a statistical comparison, event descriptions, timing, severity grading details, or an assessment of whether events were considered related to treatment. It does not report a safety analysis plan. The summary should therefore be read as a report of recorded events, not as evidence of a causal relationship or a reliable estimate of relative safety.
In general, a zero count in a small group does not establish that an event cannot occur. Conversely, an event recorded in one group does not establish that treatment caused it. Interpretation would require context about the event, the participants' underlying illness, follow-up, and the methods used to collect and classify adverse events. Those details are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, triple-masked, parallel-group pilot study was registered to compare aerosolized antibiotic treatment with aerosolized placebo in the context of intravenous antibiotics for ventilator-associated pneumonia. It also specifies a microbiological definition for recurrence and a follow-up interval of 9-21 days after initiating antibiotic therapy. These elements describe the study question and planned measurement.
What the record does not establish is whether recurrence was more or less frequent in either group. The primary-outcome population is marked “Data was not collected,” and the registry lists no analyses. Without observed recurrence data, there is no treatment-effect estimate or uncertainty interval to interpret. The absence of a reported result is not a finding of no difference, and it is not evidence that the treatments are equivalent.
The study enrolled 16 participants and is identified as a pilot. Its scale and status are relevant context, but the registry record does not state why the study was terminated, whether enrollment ended as intended, or what operational experience the investigators gained. It would be inappropriate to infer any of those details from the status field alone.
The safety figures document one serious event in the placebo group and none in the aerosolized antibiotic group, with the group-specific at-risk counts shown in the registry. Those descriptive figures do not answer the recurrence question and do not establish a causal safety difference. Similarly, secondary outcomes listed in the record represent areas of interest, not results, because outcome-specific analyses are not reported.
In general, a trial result must be read in light of its measurement, analysis, missingness, and precision. Here, the main limit is more fundamental than imprecision: the registry does not provide collected data for the primary endpoint. The appropriate conclusion is that the posted record does not permit a statistical assessment of the primary recurrence comparison. It does not support a claim of benefit, lack of benefit, or equivalence.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the distinction between a well-defined research question and an answerable result. The registry specifies a randomized comparison, a clinical population, treatment groups, and a primary endpoint with a defined sampling window and bacterial threshold. These features make the intended question recognizable. Yet the record says primary-outcome data were not collected, so the main comparison cannot be estimated from the posted information.
That distinction is important when reading trial registries. A registered endpoint is not itself a result, and an outcome list is not evidence that the corresponding measurements were completed or analyzed. Here, the record lists nine outcome measures but no analyses. Careful interpretation requires keeping the planned question separate from the available observations.
The study also demonstrates why enrollment figures should not be treated as a substitute for outcome data. Enrollment of 16 gives context for the size of the pilot, but does not reveal how many participants had an evaluable BAL, what recurrence counts were observed, or how precise a group comparison would have been. In general, sample size and outcome availability both affect statistical information; neither can create an effect estimate where no endpoint data are reported.
Finally, the registry's adverse-event summary shows how safety counts can be reported even when a primary efficacy endpoint is unavailable. Those counts are useful descriptive information, but they do not answer the primary question and should not be over-interpreted. The broader lesson is to distinguish study design, collected outcomes, analyses, and conclusions as separate layers of evidence.
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 most important trial-specific limitation for interpreting the primary question is explicit: the registry states that data for the primary recurrence outcome were not collected. There are consequently no posted event counts, effect estimates, confidence intervals, or primary-outcome analyses. The registry record does not explain why collection did not occur or whether the reason was connected with the study's terminated status.
The record reports enrollment of 16, but does not report participant characteristics, group sizes for the primary analysis, completion of follow-up, or the number with a second BAL. The adverse-event at-risk counts do not establish the analysis denominators for recurrence. The record also does not describe the randomization procedure, identify the people covered by triple masking, or report whether masking remained intact.
Several other details needed to assess analysis quality are not reported in the registry record: the statistical analysis plan, analysis population, handling of missing outcomes, multiplicity approach, reasons for termination, and sample-size justification. The record lists nine outcome measures and no analyses, so it is not possible to evaluate how secondary outcomes were summarized or whether planned analyses changed.
The registry defines recurrence using a culture threshold from a second BAL within the stated interval, but does not report whether all participants were assessed on a consistent schedule or how samples that were unavailable or uninterpretable would have been handled. These omissions limit assessment of endpoint implementation. The serious adverse event summaries provide only group counts and a summary percentage; detailed event descriptions and attribution are not reported. Together, these limitations mean that the record can describe the trial's question and some safety counts, but cannot support a statistical conclusion about the primary endpoint.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Aerosolized Antibiotics in the Treatment of Ventilator Associated Pneumonia — NCT02478710.
- Registry record last updated 2023-05-31; status last verified 2023-05.
- Results first posted 2023-05-22.
- 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
This registry record describes NCT02478710, a phase 4, randomized, triple-masked, parallel-group pilot study sponsored by Wright State University. It lists enrollment of 16, a study start of 2015-06, primary completion in 2017-02, and terminated status.
The study compared aerosolized placebo with aerosolized tobramycin or vancomycin in the context of intravenous antibiotics for ventilator-associated pneumonia. Its primary endpoint was microbiological recurrence assessed by a second BAL during 9-21 days after initiating antibiotic therapy. The registry states that primary-outcome data were not collected and lists no analyses.
Serious adverse event figures are reported for both groups, but they are descriptive and do not establish a causal difference. The record lists secondary outcomes, while outcome-specific analysis results are not reported. The primary recurrence question therefore cannot be answered from the posted record.