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 Trilogy Comparison Study - Pediatrics (NCT00810459), a randomized na study. The primary outcome is Comparable Level of Gas Exchange (Measured as Partial Pressure of Carbon Dioxide (CO2) in Arterial, Venous or Capillary Blood).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00810459 |
| Phase | NA |
| Condition | Respiratory Failure |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Single |
| Enrollment | 6 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Philips Respironics |
| Results posted | Yes |
2. Clinical Question
Population
The study is titled Trilogy Comparison Study - Pediatrics and lists respiratory failure as its condition. The registry record reports enrollment of 6 participants. Its description identifies the study as Part II and says that participants’ current ventilator mode and prescription settings were used for both devices. The participant characteristics and any more specific eligibility criteria are not reported in the registry record.
Intervention
The intervention was the Trilogy ventilator. The stated objective was to compare its performance with participants’ current ventilators, with both devices set to the participant’s current mode and prescription settings. The registry record does not report further technical details about how the settings were implemented or how use was monitored.
Comparator
The comparator was Standard of Care, described as the ventilator currently prescribed to participants. This is an existing device rather than a single named ventilator model in the record. The particular devices used, and whether device types varied among participants, are not reported in the registry record.
Primary question
The primary question concerned whether the devices produced a comparable level of gas exchange, assessed using partial pressure of carbon dioxide in arterial, venous or capillary blood after one hour of ventilator use. The endpoint is recorded as a mean, with standard deviation as its dispersion measure and mEq/L as its unit. The posted summaries are 37.0 with standard deviation 7.5 for Trilogy and 33.3 with standard deviation 11.9 for Standard of Care, each with 6 participants. A statistical comparison is not estimable in the registry record.
3. Trial Design
The registry record identifies this as a randomized, single-masked, crossover study. In a crossover design, participants receive or use more than one study condition, so each participant can contribute information under both devices. This structure can make a within-person comparison relevant: differences between people may be less influential when the treatment contrast is evaluated within each person. The record does not report the device sequence, the allocation procedure, any washout period, or the interval between device conditions. It also does not identify who was masked or describe how masking was maintained.
The enrollment was 6. The study lists Trilogy Ventilator and Standard of Care as the two device conditions; Standard of Care is described as participants’ currently prescribed ventilator. The brief description says both devices were set to participants’ current mode and prescription settings. This supports understanding the comparison as one between a study device and an individual’s current ventilator under stated settings, not as a comparison of two specified device models used under a common fixed setting.
The registry status is COMPLETED. The recorded start date is 2008-03-10 and the primary completion date is 2009-01-26. Phase is recorded as NA, which is consistent with the record describing a device comparison rather than identifying a drug phase. No study design details beyond randomization, single masking and crossover are reported in the registry record. In particular, the rationale for enrollment, the planned sequence and timing, and the methods for handling departures from the assigned device order are not reported.
The crossover feature matters for interpretation of the outcome summaries. A mean and standard deviation for each device describe the arm-level values but do not show how each participant’s measurement changed between devices. The registry record does not post participant-level paired differences or an analysis of those differences. Consequently, the intended within-person structure cannot be reconstructed from the posted summaries, and the record does not support a statistical estimate of the device contrast.
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 | Trilogy Ventilator First, Then Standard of Care Ventilator | Standard of Care Ventilator First, Then Trilogy Ventilator |
|---|---|---|
| STARTED | 4 | 2 |
| COMPLETED | 4 | 2 |
| NOT COMPLETED | 0 | 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 | All Participants Consented |
|---|---|---|
| Participants analysed | 6 | |
| Age, Continuous | years | 7.2 (SD 6.4) |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 5 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 1 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 5 |
| Region of Enrollment: Canada | participants | 6 |
6. Primary Endpoint
The registry lists the primary outcome as Comparable Level of Gas Exchange (Measured as Partial Pressure of Carbon Dioxide (CO2) in Arterial, Venous or Capillary Blood), measured over After one hour of ventilator use.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mEq/L |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is described as a comparable level of gas exchange measured by partial pressure of carbon dioxide (CO2) in arterial, venous or capillary blood. The recorded unit is mEq/L, the summary parameter is the mean, and dispersion is represented by standard deviation. The measurement timeframe is after one hour of ventilator use. The record does not specify which blood sampling type was used for each participant or report the sampling procedures.
Carbon dioxide measurement is used as a physiologic indicator in this study because the stated research objective is to compare ventilator performance in relation to gas exchange. The endpoint therefore concerns a measured physiologic value, not a patient-reported outcome or a clinical event. The study description calls the aim comparability, but the record does not report a prespecified numerical margin defining what difference would count as comparable. Without such a margin and a reported comparison with uncertainty, the posted means alone cannot establish statistical equivalence or non-inferiority.
The posted mean is 37.0 for Trilogy and 33.3 for Standard of Care. Their reported standard deviations are 7.5 and 11.9, respectively, with 6 participants in each condition. These summaries describe the recorded values in each group; they do not communicate the within-participant contrast that is especially pertinent in a crossover study. The statistical comparison is not estimable in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary outcome summaries report a mean of 37.0 for Trilogy Ventilator and 33.3 for Standard of Care, with standard deviations of 7.5 and 11.9, respectively. Each condition has a reported sample size of 6. The outcome was measured after one hour of ventilator use, and the record describes it as partial pressure of carbon dioxide in arterial, venous or capillary blood. These figures are descriptive summaries of the observations recorded for each condition.
The registry record does not report a test statistic, p-value, confidence interval, or an estimate of the treatment contrast. It also identifies values as missing or not estimable for a two-arm comparison of this continuous endpoint. Thus, although condition-specific means and standard deviations are present, a statistical comparison is not available from the record. The record reports zero posted analyses. It does not report whether the absence of an estimable comparison reflects unavailable paired observations, another analytic limitation, or a different reason.
Because the study is a crossover, the treatment contrast ordinarily depends on how measurements under the two devices relate within the same participants. Separate means and standard deviations do not show that pairing. A confidence interval for a paired contrast would describe the range of values compatible with the data and analysis under the method’s assumptions; no such interval is reported. Without it, the precision of the difference between device conditions cannot be assessed from the registry results. The separate standard deviations describe variation within each condition, not uncertainty in a paired contrast.
The title and objective use the idea of comparability, but the registry record does not define a margin for acceptable differences. A finding of no statistically significant difference, if one had been reported, would not by itself demonstrate that the devices are equivalent. An equivalence assessment requires a prespecified range of differences considered unimportant and an estimate sufficiently precise to lie within that range. Neither an equivalence margin nor an inferential comparison is reported. The posted summaries therefore should not be read as a formal equivalence result.
The summary values are also based on a small enrolled cohort, and the registry record does not report a sample-size justification. The limited amount of information is relevant to precision, but no precision measure for the primary contrast is available. No recalculated contrast should be substituted for the sponsor’s analysis: the record marks the comparison as not estimable, and the posted arm summaries alone do not contain the within-participant information needed for an appropriate crossover analysis.
Three secondary outcomes are named: Heart Rate, Minute Ventilation and Tidal Volume. The record lists 5 outcome measures in total, but it does not post analyses for them. Their result values and statistical comparisons are not reported in the registry record. The primary outcome summaries should therefore be understood as descriptive posted data, not as a complete inferential account of the study.
9. Statistical Methods Explained
What do the mean and standard deviation describe?
The mean is a summary of the observed measurements in a condition. For this primary endpoint, the record reports a mean for Trilogy and a separate mean for Standard of Care. The standard deviation describes how dispersed the individual measurements are around their condition-specific mean. It is not the same as a standard error, and it is not a confidence interval for the difference between devices. The posted standard deviations characterize variation among measurements; they do not state how precisely the device contrast was estimated.
General explanation: continuous outcomes are often summarized with a mean and standard deviation when a mean is a useful description of the data. These summaries can be informative, but they omit the pattern of association between observations from the same person. That omission is especially important in crossover research, where observations under the different conditions are linked by participant.
Why is the crossover structure important?
General explanation: a crossover analysis can use each participant as their own comparison. A paired analysis considers the difference between each person’s measurement under one condition and that same person’s measurement under the other condition. The variability of those paired differences depends on how strongly the two measurements are related within participants. Separate condition means and standard deviations do not reveal that relationship. Participant-level paired data, or an appropriate summary of the paired differences, is needed to estimate the contrast and its uncertainty by that route.
The registry record classifies the study as crossover, but does not report sequence, period, washout, or participant-level paired results. It does not report the statistical model used to account for the crossover design. Since the record also states that a two-arm comparison for the continuous endpoint is not estimable, the available summaries do not permit a defensible reconstruction of the intended inferential analysis.
What would a confidence interval add?
General explanation: a confidence interval expresses uncertainty around an estimated effect under a stated statistical method and its assumptions. For a crossover comparison, an interval for the within-participant contrast would communicate both the estimated contrast and its precision. A narrow interval would indicate more precise estimation than a wide interval, but an interval’s interpretation also depends on the analysis and the question being asked. No confidence interval for the primary comparison is reported in the registry record, so its precision cannot be evaluated from posted inferential statistics.
A confidence interval is not automatically an equivalence assessment. To assess equivalence, an acceptable range of effects must be specified in advance, and the interval must be considered against that range. The study objective mentions comparability, but a margin for comparability is not reported in the registry record. Accordingly, the descriptive means cannot establish equivalence.
What is the role of the planning illustrations?
The record describes planning illustrations based on the observed effect, with two-sided significance level 0.05, equal allocation between conditions and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not a report of the study’s original design rationale. The sample-size justification used when the study was designed is not reported in the registry record.
General explanation: a sample-size planning calculation asks how much information a future study might need under specified assumptions. Its result depends on the target effect, variability, statistical method, significance level and desired power. If the target effect is framed as a fraction of an observed effect, that is an illustrative scenario rather than independent evidence that the observed effect is reliable. Such calculations do not recover missing outcome data or resolve the lack of a posted comparison. They are not observed power and should not be interpreted as a retrospective measure of whether this study had enough information to detect an effect.
The record’s stated planning assumptions describe equal allocation and a normal approximation. General explanation: a normal approximation uses a mathematical distribution to approximate the sampling behavior of an estimate. Whether it is adequate depends on the data and design. The record does not report diagnostic checks, a specific variance assumption for a crossover analysis, or details that would permit assessment of the planning method’s fit to the trial.
Why can over-dispersion matter?
General explanation: over-dispersion means that observed variability exceeds what a chosen statistical model assumes. When a model understates variability, its uncertainty estimates may be too small; when it handles variability appropriately, its intervals and tests can better reflect the data. The primary endpoint is continuous, and no model-based comparison is reported. The record gives condition-specific standard deviations but does not report a model, residual diagnostics, or an assessment of over-dispersion. It would therefore be inappropriate to claim that over-dispersion was present or addressed.
For this endpoint, the key methodological issue evident from the record is not a reported diagnostic problem but the absence of an estimable two-arm comparison and of paired information in the posted summaries. General methodological concepts can explain what would matter in a crossover analysis, but they cannot replace the unreported analysis or supply an effect estimate.
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.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Trilogy Ventilator | 6 | 37.000 | 7.500 | 29.129 to 44.871 |
| Standard of Care | 6 | 33.300 | 11.900 | 20.812 to 45.788 |
R code and output
arm <- c("Trilogy Ventilator", "Standard of Care")
n <- c(6, 6)
m <- c(37, 33.3)
sp <- c(7.5, 11.9)
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 Trilogy Ventilator 6 37.000 7.500 29.129 44.871
CARM Standard of Care 6 33.300 11.900 20.812 45.78811. Multiplicity, Missing Data and Analysis Populations
The registry record lists 5 outcome measures and names 3 secondary outcomes: Heart Rate, Minute Ventilation and Tidal Volume. It reports zero analyses. Results for the secondary outcomes and any statistical comparisons among outcomes are not reported in the registry record. It also does not report a plan for controlling multiplicity, such as a hierarchy of outcomes or an adjustment for multiple comparisons.
General explanation: when multiple outcomes or multiple statistical tests are considered, the chance of at least one apparently notable result can increase. A prespecified analysis strategy can clarify which outcome is primary and how secondary findings should be interpreted. The record identifies a primary outcome, but the broader analysis plan and any multiplicity strategy are not reported. No inference about unreported secondary outcomes is possible.
The record does not describe missing-data counts, reasons for missingness, or methods for handling missing observations. It also does not report whether every enrolled participant contributed data at each period or whether any participant discontinued. Those details are particularly relevant in a crossover study because a complete within-participant comparison requires measurements under both conditions. The statement that the continuous two-arm comparison is not estimable does not identify the specific reason it could not be estimated.
Analysis populations are not described. The registry record does not state whether analyses were planned for all randomized participants, for participants who completed both conditions, or under another definition. It does not report exclusions, protocol deviations or sensitivity analyses. Consequently, the primary summaries cannot be linked to a clearly defined analysis population, and the handling of incomplete paired observations is unknown.
12. 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 |
|---|---|---|---|
| Trilogy Ventilator | 0 | 6 | 0.0% |
| Standard of Care Ventilator | 0 | 6 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Trilogy Ventilator | 0 of 6 |
| Standard of Care Ventilator | 0 of 6 |
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 |
|---|---|
| Trilogy Ventilator | 0 of 6 |
| Standard of Care Ventilator | 0 of 6 |
The posted adverse-event figures list 6 participants at risk in each device condition. For Trilogy Ventilator, 0 serious adverse events are reported among 6 at risk, and 0 other adverse events are reported among 6 at risk. For Standard of Care Ventilator, the corresponding figures are also 0 serious adverse events and 0 other adverse events among 6 at risk. Deaths are reported as 0 in both conditions. No top serious-event terms are listed.
These figures describe the registry’s posted counts. They should not be read as proof that no event could occur or as a precise estimate of comparative safety. The record does not provide event-level descriptions, timing, severity grading, relatedness assessments, or details of how adverse events were collected. It also does not report an inferential comparison of safety outcomes. The small enrollment means that the posted counts summarize only the participants included in this record; the registry does not provide a basis for broader safety conclusions.
13. What the Result Does, and Does Not, Mean
The posted results establish that the registry record contains condition-specific summaries for the primary continuous endpoint: mean partial pressure of carbon dioxide after one hour of ventilator use. The reported means are 37.0 for Trilogy and 33.3 for Standard of Care, with standard deviations of 7.5 and 11.9, and 6 participants reported in each condition. They provide descriptive information about the recorded measurements under each device condition.
The record does not establish the size or precision of a within-participant treatment contrast. It reports no inferential comparison, confidence interval or p-value, and it marks the two-arm comparison as not estimable. These omissions matter because the design is crossover and because separate condition summaries do not show each participant’s paired measurements. The observed means alone cannot establish whether the devices are statistically different, similar, equivalent or non-inferior.
The stated objective of comparing performance and the endpoint’s description of comparable gas exchange are research aims, not results. A formal claim of comparability would require a defined criterion for acceptable difference and an analysis capable of assessing that criterion. A criterion and inferential result are not reported in the registry record. No conclusion about clinical benefit or harm follows from these summaries.
The record’s adverse-event counts report zero serious events, zero other events and zero deaths in each device condition. These counts describe what is posted, but they do not provide a comparative safety analysis or establish absence of risk. The secondary outcomes are named, but their results are not reported. Overall, the registry information supports a narrow descriptive account of the primary outcome and posted safety counts, while leaving the principal statistical comparison and its uncertainty unresolved.
14. Why This Trial Matters Statistically
This study illustrates a central issue in crossover trial reporting: the design’s main comparison is within participants, while the registry posts separate summaries by condition. Means and standard deviations are useful descriptions, but they do not preserve the pairing that connects each participant’s measurements across device conditions. Without paired results or an analysis of the within-person contrast, the intended design cannot be fully interpreted statistically.
The distinction between a study objective and an estimable result is also important. The objective invokes comparable gas exchange, but the record does not post a comparison or a prespecified comparability margin. Descriptive values can show what was recorded under each condition, but they cannot by themselves answer a formal equivalence question. This distinction applies broadly to clinical research: a stated aim does not substitute for the estimate, uncertainty and decision criterion needed to evaluate it.
The record also demonstrates why transparency about analysis populations and missing observations matters. It reports enrollment and condition-specific sample sizes, yet does not explain the basis for the statement that the two-arm comparison is not estimable. Information about paired availability, exclusions and analysis methods would help readers understand the gap between posted summaries and an inferential result. Those details are not reported in the registry record.
Finally, planning illustrations should be separated from the study’s original design justification and from observed statistical evidence. The registry describes assumptions for illustrative planning, but does not report the original sample-size rationale or a primary comparison. Such distinctions help prevent hypothetical planning calculations or descriptive outcomes from being mistaken for evidence about the precision or performance of a completed trial.
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 contains limited detail for evaluating the primary comparison. Although it reports means, standard deviations and sample sizes by condition, the two-arm comparison is identified as not estimable and no analysis is posted. Participant-level paired values, an estimate of the within-person contrast, and its uncertainty are not reported. This prevents assessment of the principal treatment comparison using the crossover structure.
Important design details are also absent. The randomization sequence, device order, period structure, washout arrangements and masking procedures are not reported. The record identifies single masking but does not say who was masked. It does not specify which blood sampling type was used for each measurement or provide details of measurement timing beyond after one hour of ventilator use.
The registry does not report eligibility criteria, participant characteristics beyond the pediatric study title and respiratory failure condition, or a sample-size justification. It does not explain why the primary comparison was not estimable. Missing-data counts, reasons for missingness, analysis populations, protocol deviations and sensitivity analyses are not reported in the registry record.
Although 3 secondary outcomes are named, their results and analyses are not posted. The record does not report multiplicity handling or a complete statistical analysis plan. It also does not provide a prespecified margin for the stated comparability objective. These limitations mean that the primary data can be described, but the inferential strength and intended criteria for interpreting comparability cannot be assessed from the registry record.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Trilogy Comparison Study - Pediatrics — NCT00810459.
- Registry record last updated 2021-02-03; status last verified 2021-01.
- Results first posted 2021-02-03.
- 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.
19. Record Summary
NCT00810459 is the completed Trilogy Comparison Study - Pediatrics, sponsored by Philips Respironics. The registry record lists randomized allocation, single masking and a crossover model, with enrollment of 6. Its recorded start date is 2008-03-10 and primary completion date is 2009-01-26. The study concerns respiratory failure and compares the Trilogy ventilator with participants’ currently prescribed ventilators.
The primary endpoint is mean partial pressure of carbon dioxide in arterial, venous or capillary blood after one hour of ventilator use, recorded in mEq/L with standard deviation. The posted means are 37.0 for Trilogy and 33.3 for Standard of Care; the corresponding standard deviations are 7.5 and 11.9, with 6 participants reported for each condition. The two-arm comparison is not estimable in the record, and no analyses are posted. Three secondary outcomes are named, but their results are not reported. Posted adverse-event figures show zero serious events, zero other events and zero deaths in each condition.