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 Effect of Daily Low Dose Aspirin on Exhaled Inflammatory Mediators in Normal Subjects (NCT00898222), a na na study. The primary outcome is Change in Exhaled Inflammatory Mediator Levels.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00898222 |
| Phase | NA |
| Condition | Healthy |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 4 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Brigham and Women's Hospital |
| Results posted | Yes |
2. Clinical Question
Population
Healthy volunteers, described in the registry record as normal subjects. Enrollment was 4.
Intervention
Low-dose daily aspirin. The arm description specifies treatment for two weeks.
Comparator
No separate comparator group is recorded. The study is described as a single-group study, and allocation is listed as NA.
Primary question
Whether exhaled inflammatory mediator levels change after daily low-dose aspirin, as assessed by the recorded primary outcome.
The registry states the hypothesis that low-dose aspirin does not change exhaled inflammatory breath mediators in normal subjects. The primary outcome is titled Change in Exhaled Inflammatory Mediator Levels and is expressed in pg/mL. It is described as a mean with full range and as using descriptive statistics. The record gives the timeframe as baseline and 6 months, while the intervention description specifies two weeks of aspirin. The relationship between these time references is not explained in the registry record, so they cannot be reconciled from the record alone.
This is not a comparison of aspirin with a control treatment: no distinct control group is listed, and the record identifies the study model as single group. Consequently, its stated question concerns measurements within the enrolled group, not a difference between randomized treatment groups. Numerical outcome results, including the observed change, are not reported in the registry record. The record therefore states the research question and the intended measurement, but does not establish the direction or size of any change.
3. Trial Design
The registry record describes a completed, single-group study sponsored by Brigham and Women's Hospital. Its status is COMPLETED, enrollment is 4, and the condition is listed as Healthy. The study began in 2009-05, with primary completion in 2009-08. The phase and allocation are listed as NA. Masking is listed as NONE. These entries describe the structure recorded in the registry; they do not supply additional protocol details.
The intervention is aspirin, classified as a drug. The arm description says that healthy volunteers received low-dose daily aspirin for two weeks. No separate control arm or like-for-like comparator is recorded. The registry also notes that this is not a randomized comparison. Accordingly, interpretation should not treat the study as if participants had been assigned to aspirin and control groups, or infer a between-group treatment contrast.
One primary outcome measure is listed. Its title is Change in Exhaled Inflammatory Mediator Levels; the unit is pg/mL, the summary is a mean with full range, and the description says descriptive statistics. The outcome timeframe is recorded as baseline and 6 months. That timeframe does not match the two-week duration in the arm description, and the record does not explain the discrepancy. No further protocol detail is reported in the registry record about the timing of measurements, the particular mediators assessed, or how the measurements were collected.
The record reports zero analyses. It does not report a statistical analysis plan, a sample-size justification for the enrolled study, or details of any analysis population. The completed status indicates the study's recorded status, but by itself does not provide outcome findings or clarify whether all planned measurements were obtained.
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 | Aspirin |
|---|---|
| STARTED | 4 |
| COMPLETED | 4 |
| NOT COMPLETED | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Aspirin |
|---|---|---|
| Participants analysed | 4 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 4 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 26 (SD 2.94) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 2 |
| Region of Enrollment: United States | participants | 4 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Exhaled Inflammatory Mediator Levels, measured over baseline and 6 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | pg/mL |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled Change in Exhaled Inflammatory Mediator Levels. It measures the recorded change in levels of inflammatory mediators in exhaled breath, with results expressed in pg/mL. The registry describes the summary as a mean with full range and the analysis as descriptive statistics. The timeframe is listed as baseline and 6 months. Separately, the intervention description specifies two weeks of daily low-dose aspirin; the record does not explain how that treatment duration relates to the stated outcome timeframe.
In general, an outcome based on change uses measurements at different times to describe how a quantity varies within the study group. A mean gives a central summary across participants, while the full range describes the lowest and highest observed values. Reporting both can give readers a sense of the group average and the spread of observed measurements, although the range can be strongly influenced by individual observations, particularly in a very small group.
Exhaled mediator levels are the measurement named in this study's primary outcome, so they directly address the stated research question about inflammatory breath mediators. However, the numerical baseline and follow-up measurements, the calculated change, and the full range are not reported in the registry record. The record therefore identifies what was intended to be measured, but it does not permit readers to quantify the observed change or its variability.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a small, single-group study in healthy volunteers, with enrollment of 4 and a planned intervention of daily low-dose aspirin. Its stated hypothesis is that low-dose aspirin does not change exhaled inflammatory breath mediators in normal subjects. The record lists one primary outcome, but it does not report numerical outcome results. There is no recorded mean change, range, confidence interval, or test result from which to describe the observed pattern or its precision.
The outcome timeframe is recorded as baseline and 6 months, while the arm description says aspirin was taken for two weeks. This mismatch matters because the timing of measurements determines what change is being described and how it relates to the intervention. The registry record does not clarify whether 6 months refers to a follow-up measurement, another period, or a registry entry that does not align with the intervention description. No assumption about the intended timing should replace that missing detail.
Because the study is single group and no comparator is recorded, the design does not provide a randomized between-group estimate. A within-group change, if it had been reported, would describe measurements among the enrolled volunteers over time. In general, such a change cannot by itself separate an intervention-associated pattern from changes that might occur over time or from other influences. The posted record includes no numerical results with which to assess even that within-group pattern.
The absence of an analysis result is not evidence that the outcome did not change. It also does not establish that it did change. The stated hypothesis is a research question, not a result. With no reported effect estimate or uncertainty interval, the direction, magnitude, and precision of any change remain unknown from the registry record.
Enrollment of 4 is important context for the scope of the study. In general, results from a very small group are limited in how precisely they can characterize a population, and an individual observation may have substantial influence on a mean or range. Here, the lack of posted measurements prevents assessment of the actual variability or of how individual observations relate to the mean. The record does not report participant-level data or additional analyses.
The record also reports no separate control group, no randomized allocation, and no analysis details. Therefore, readers should not interpret the record as evidence of a treatment contrast or as a formal test of the stated null hypothesis. The most defensible reading is descriptive: the registry documents a completed study with a stated measurement objective, but numerical findings and the details needed to evaluate them are not reported in the registry record.
9. Statistical Methods Explained
The registry describes the primary outcome using descriptive statistics. It names a mean and full range, with the measurement unit pg/mL. It does not report the actual summary values or an inferential analysis. The methods discussion below explains the statistical ideas relevant to the stated outcome in general; it does not imply that unreported analyses were performed.
What does a mean summarize?
In general, a mean is the arithmetic average of the observed measurements. For a study outcome defined as change, the mean can summarize the average change within the group, provided the relevant measurements and definition of change are available. A mean is useful for conveying a central value, but it does not show whether observations are closely grouped or widely dispersed. In a group with enrollment of 4, any one observation can have a noticeable influence on the average. The registry record does not give the individual measurements, the mean, or the numerical change.
What does a full range add?
In general, the full range reports the smallest and largest observed values. It gives a direct indication of the span of measurements, but it uses only the two endpoints and does not describe how observations are distributed between them. A range can be especially sensitive to an unusually low or high observation. For a change outcome, a range would need to be clearly tied to the values being summarized, such as changes or measurements at a specified time. The registry identifies full range as the dispersion summary but does not state the numerical endpoints or give further detail about the values to which they apply.
What can a confidence interval tell a reader?
In general, a confidence interval expresses uncertainty around an estimate under a specified statistical method and its assumptions. Its width is informative about precision: a wider interval indicates less precision than a narrower interval for the same type of estimate. It does not guarantee that the true value lies within the interval, and it is not a measure of the probability that a hypothesis is true. No confidence interval is reported in the registry record, so the precision of the primary outcome estimate cannot be assessed from this record.
What would a hypothesis test contribute?
In general, a hypothesis test evaluates how compatible observed data are with a specified null hypothesis under a statistical model. A p-value does not measure the size or importance of an effect, and a value alone cannot communicate precision. Interpretation requires the estimate, its uncertainty, and a clear account of the test and analysis population. The registry states a hypothesis of no change but reports zero analyses and no p-value or test result. It is therefore not possible to determine from the record whether that hypothesis was formally tested.
How should the planning illustration be read?
The registry's sample-size assumptions describe planning illustrations computed from an observed effect, not the trial's own design. They specify 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. The record also distinguishes total events for time-to-event illustrations from participants per arm for other illustrations. These are assumptions for planning examples, not evidence that the study used a two-arm design. The actual study is recorded as single group, with allocation listed as NA and no separate control arm.
Such planning illustrations are not observed power and should not be read as a retrospective measure of what the completed study could detect. Nor do they establish the sample-size rationale for enrollment of 4. The record does not report a trial-specific sample-size justification or provide the numerical effect estimates underlying any planning illustration. No numerical planning value should be treated as an observed trial result.
Why does the design affect interpretation?
In general, a single-group study can describe observed measurements in that group, but it does not provide the concurrent randomized comparison that would support a direct between-group estimate. A within-group change can be affected by time and other influences as well as the intervention. Randomization and a suitable comparison group can help address some alternative explanations, but neither is recorded for this study. The analysis should therefore be interpreted in relation to the single-group design rather than as a randomized treatment comparison.
There is also a timing issue to resolve before interpreting a change estimate: the arm description says two weeks, whereas the primary outcome timeframe is baseline and 6 months. Statistical summaries are meaningful only when the measurement times and outcome definition are clear. The registry record does not explain that discrepancy. In addition, the record's statement that descriptive statistics were used does not specify whether the reported change would be based on paired observations, how missing measurements would be handled, or whether any adjustment would be made. Those details are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure and reports zero analyses. It does not describe a set of secondary outcomes, multiple hypothesis tests, or an adjustment for multiplicity. With only one listed outcome, the record still does not establish how many mediator measurements, time points, or statistical comparisons were intended; those details are not reported in the registry record. A multiplicity strategy therefore cannot be assessed from the record.
In general, multiplicity concerns arise when multiple outcomes, time points, subgroups, or tests are considered. Testing many hypotheses can increase the chance of finding an apparently notable result by chance if the tests are interpreted without regard to their number. Adjustments or a prespecified hierarchy can be used in some settings, but no such approach is reported. This is not evidence that no approach was used; it means the registry record does not describe one.
Missing-data handling is also not reported in the registry record. It does not state whether measurements were missing, how incomplete observations would be treated, or whether participants with unavailable follow-up data would be included in a particular analysis. The record does not specify an analysis population, such as whether the primary summary would include all enrolled volunteers or only those with measurements at both time points.
These omissions limit assessment of how the stated descriptive outcome would have been calculated and who contributed to it. The record identifies enrollment of 4, but it does not report the number with usable outcome measurements at each time point. No conclusion about completeness of follow-up, exclusions, or the handling of missing observations can be drawn from the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Aspirin | 0 | 4 | 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 |
|---|---|
| Aspirin | 0 of 4 |
The registry lists an aspirin group with 4 participants at risk for serious adverse events and 0 affected. For other adverse events, it also lists 4 at risk and 0 affected. These figures describe what the registry reports for the recorded group; they should not be interpreted as a comparative safety estimate because no separate control group is recorded.
The death entry is null, so deaths are not reported in the registry record. The record does not list serious adverse-event terms. A count of 0 affected in the posted fields means no affected participants are recorded in those categories; it does not show the frequency of every possible symptom or event unless those events are included in the registry's defined reporting categories. Further details about adverse-event definitions, surveillance, timing, or collection procedures are not reported in the registry record.
In general, safety counts describe observed events within the group and depend on the size of the group, the observation period, and how events were sought and classified. With enrollment of 4, the figures are limited in their ability to characterize uncommon events or variation across a broader population. The registry record does not report enough detail to assess those aspects, and the recorded counts should not be treated as proof that no adverse events of any kind occurred.
12. What the Result Does, and Does Not, Mean
The record documents a completed study of daily low-dose aspirin in healthy volunteers, with enrollment of 4 and a primary outcome focused on change in exhaled inflammatory mediator levels. It states a hypothesis that low-dose aspirin does not change exhaled inflammatory breath mediators in normal subjects. It does not report numerical results for that outcome. Consequently, the posted record does not establish whether measured levels increased, decreased, or remained similar, nor does it quantify the size or precision of any change.
The study is recorded as single group, with allocation listed as NA and no separate comparator. It therefore does not document a randomized treatment-versus-control contrast. In general, measurements within one group can describe what was observed over time, but they cannot alone distinguish an intervention-associated change from other explanations. Because the outcome values and analysis results are not reported, even the descriptive within-group pattern cannot be reviewed.
The timing information also remains unclear: the intervention is described as lasting two weeks, while the outcome timeframe is baseline and 6 months. The registry record does not explain the difference. That missing detail limits interpretation of what period the primary change was intended to cover.
The adverse-event entries record 0 affected among 4 at risk for both serious and other adverse events. These counts should be read as registry entries for the recorded group, not as a comparison with another group or a complete account of all possible events. Deaths are not reported in the registry record.
Overall, the record supports a limited description of study design, intervention, enrollment, and intended measurement. It does not provide the outcome estimates, uncertainty, analysis details, or timing clarification needed to evaluate the primary result. A hypothesis is not a finding, and missing numerical results should not be interpreted as evidence for either no change or a change.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of the difference between a clearly named research question and a reportable numerical result. The registry identifies a primary outcome, its unit, a summary format, and a stated hypothesis. Yet the numerical measurements and analyses are not reported in the registry record. Without those results, readers cannot evaluate the observed direction, magnitude, spread, or precision.
The record also illustrates why design labels matter. A single-group study can describe outcomes in its participants, but it does not create a randomized comparison with a control group. A planning illustration based on equal allocation between two arms does not change the recorded study design. Keeping planning assumptions separate from the design actually recorded prevents hypothetical calculations from being mistaken for evidence from a comparison that did not occur.
Small enrollment is another important interpretive feature. With 4 participants, a mean and full range could be strongly influenced by individual observations. In general, this makes transparent reporting of the underlying measurements and uncertainty especially useful. Those numerical details are not reported in the registry record, so the degree of variability and the contribution of individual observations cannot be assessed.
Finally, the different time references in the intervention and outcome descriptions demonstrate that statistical interpretation depends on clear definitions. A change between measurements can only be understood when the measurement times and the intervention period are unambiguous. The record does not resolve the two-week versus 6-month timing. Together, these features emphasize the value of reporting outcome estimates, uncertainty, analysis methods, participant counts at each time point, and clear timing information alongside a study's stated hypothesis.
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 primary limitation for interpreting the findings is that numerical outcome results are not reported in the registry record. Although the record identifies a mean with full range and descriptive statistics, it gives no baseline value, follow-up value, change estimate, range endpoints, or uncertainty interval. The effect's direction, size, and precision therefore cannot be assessed.
Enrollment was 4, and the study is recorded as single group. This small group limits the scope of what the study could describe about healthy volunteers, while the absence of a separate comparator means there is no recorded randomized between-group contrast. The registry record does not report participant-level measurements or analysis details that might otherwise help readers understand variation within the group.
The intervention description specifies two weeks of daily low-dose aspirin, but the primary outcome timeframe is listed as baseline and 6 months. This inconsistency is not explained in the registry record. Details of the mediator measurements, including which mediators were assessed and the collection procedures, are also not reported in the registry record.
The record reports zero analyses and does not describe the analysis population, missing-data handling, or any prespecified statistical analysis plan. It also does not report a trial-specific sample-size justification. The listed planning assumptions refer to illustrations rather than the actual single-group design and do not replace a study-specific rationale. Finally, adverse-event counts are reported for the recorded group, but event definitions and surveillance details are not reported in the registry record. These gaps constrain both efficacy-oriented interpretation of the primary outcome and assessment of the scope of the safety reporting.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effect of Daily Low Dose Aspirin on Exhaled Inflammatory Mediators in Normal Subjects — NCT00898222.
- Registry record last updated 2015-09-25; status last verified 2015-09.
- Results first posted 2014-11-04.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record identifies NCT00898222 as a completed, single-group study sponsored by Brigham and Women's Hospital. It lists healthy volunteers, enrollment of 4, no masking, and aspirin as the intervention. The arm description specifies low-dose daily aspirin for two weeks. The study began in 2009-05 and reached primary completion in 2009-08.
One primary outcome is listed: Change in Exhaled Inflammatory Mediator Levels, measured in pg/mL and described as a mean with full range using descriptive statistics. Its timeframe is recorded as baseline and 6 months, which is not reconciled with the two-week intervention description. The record states a hypothesis of no change but reports zero analyses and no numerical primary outcome results.
No separate comparator is recorded. Serious and other adverse-event entries each list 0 affected among 4 at risk; deaths are not reported in the registry record. The record does not provide the outcome estimates, analysis details, missing-data approach, or timing clarification needed for a fuller statistical interpretation.