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 Compass Device CVC Trial (NCT03056859), a registered phase not stated study. The primary outcome is Operator Satisfaction.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03056859 |
| Phase | Phase not stated |
| Condition | Blood Pressure |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of New Mexico |
| Results posted | Yes |
2. Clinical Question
Population
The registry summary describes consenting patients with BMI ≥35 who required central venous catheterization for clinical reasons independent of the study. It states that investigators planned to enroll 40 patients; the record separately reports enrollment of 20. The record does not describe the characteristics of the enrolled patients or explain the difference between planned and reported enrollment.
Intervention
Participants underwent central venous catheter placement with an extravascular blood pressure transducer. The summary describes the device as a compact, sterile, single-use transducer that measures pressure outside the blood vessel. Its measurement is intended to aid confirmation of appropriate venous access.
Comparator
No comparator group is described. The study is identified as single-arm and observational, and the allocation method is not stated. The record therefore does not establish a like-for-like comparison between catheter placement with the device and catheter placement without it.
Primary question
The primary outcome is operator satisfaction, measured on a scale from 0 to 10, with 0 meaning totally dissatisfied and 10 meaning totally satisfied. Satisfaction is assessed at 15 minutes. The registry specifies a median and inter-quartile range as the summary measure, but does not report the observed score or its distribution. The record therefore describes what the study intended to assess, but does not report the primary outcome result.
3. Trial Design
This completed study is registered as an observational, single-arm trial of an extravascular blood pressure transducer used during central venous catheter placement. The listed intervention is the device, and the arm description specifies catheter placement with the transducer. The registry does not describe a separate group receiving the procedure without the device, and it does not state an allocation method. A randomized treatment comparison is therefore not described.
The study concerns central venous catheterization in obese patients. The brief summary describes a plan to enroll consenting patients with BMI ≥35 who required catheterization for clinical reasons independent of the study. It also says investigators planned to enroll 40 patients, while the registry record reports enrollment of 20. The record does not explain this difference, nor does it report participant-level characteristics that would clarify who was enrolled.
The registry lists the study start as 2017-02-17, primary completion as 2020-02-10, and status as completed. These dates indicate the recorded study timeline, but do not establish when all data were analyzed or whether results were published elsewhere. The record lists three outcome measures, including operator satisfaction and two secondary outcomes concerning arterial puncture incidence and an implement used at the time of arterial puncture, if any.
The registry describes the primary outcome as a score summarized by its median and inter-quartile range, measured at 15 minutes. It lists no statistical analyses. The record does not report a protocol, a sample-size justification for the enrolled study, or a detailed analysis plan. Consequently, the design can be described from the stated single-arm procedure and outcome measures, but important design and analysis details are not reported in the registry record.
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 | Enrolled Patients |
|---|---|
| STARTED | 20 |
| COMPLETED | 20 |
| 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 | Enrolled Patients |
|---|---|---|
| Participants analysed | 20 | |
| Age, Continuous | years | 64 (52 to 68) |
| Sex: Female, Male: Female | Participants | 10 |
| Sex: Female, Male: Male | Participants | 10 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 20 |
| Body Mass Index | kg/m^2 | 39.6 (36.2 to 43.2) |
6. Primary Endpoint
The registry lists the primary outcome as Operator Satisfaction, measured over 15 minutes.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | score on a scale |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is operator satisfaction with the catheterization procedure, assessed 15 minutes after the procedure. The registry defines a 0–10 scale: 0 means totally dissatisfied and 10 means totally satisfied. The intended summary is the median and inter-quartile range. The median describes the middle of the observed scores, while the inter-quartile range describes the spread of the middle half of those scores. These are general statistical descriptions of the stated summary method.
Satisfaction is a measure of the operator’s experience, rather than a direct measure of a clinical outcome for the patient. As a general matter, such a measure can describe how acceptable or usable a procedure is to the person performing it. It does not by itself establish that a device improves clinical outcomes or that any difference is caused by the device, especially when the study has no comparator group.
The registry does not report the observed median, inter-quartile range, individual scores, or the number of operators contributing scores. It also does not describe how satisfaction was collected beyond the scale and assessment time. The endpoint is therefore defined, but its actual result and the precision with which it was measured are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a completed study with reported enrollment of 20 participants and three outcome measures. It does not include a numerical result for the primary endpoint, operator satisfaction. Although the endpoint is defined as a 0–10 score assessed at 15 minutes and summarized by median and inter-quartile range, those summary values are not reported in the registry record. As a result, the posted record does not describe the observed level or variability of operator satisfaction.
The record also lists arterial puncture incidence and an implement used at the time of arterial puncture, if any, as secondary outcomes. Their results are not reported in the registry record. No statistical analyses are listed. The record therefore supplies no estimated effects, confidence intervals, p-values, or other inferential results for the primary or secondary outcomes. The absence of these results means the precision and uncertainty of any outcome estimates cannot be assessed from this record.
The study is single-arm and observational, with no comparator group described. This design can document outcomes among participants receiving the procedure with the transducer, but it does not provide a like-for-like estimate of what would have happened to comparable participants without the device. Even if outcome values were reported, a one-group summary alone would not separate the device’s contribution from other influences on the observed outcomes. This is a general limitation of interpreting uncontrolled observations, not a claim about what occurred in this study.
The record reports 20 participants enrolled, while the brief summary says investigators planned to enroll 40. It does not reconcile the two figures or explain whether the planned number changed. The registry also does not report participant characteristics, missing outcome counts, or analysis populations. These omissions make it difficult to assess how representative the analyzed participants might be, or whether all enrolled participants contributed to outcome summaries.
The safety record lists 20 participants at risk for serious adverse events and 0 affected, 20 at risk for other adverse events and 0 affected, and 0 deaths. These are recorded counts, not evidence that adverse events are impossible or that the procedure is free of risk. Taken together, the registry record documents the study’s design, stated outcomes, enrollment and recorded safety counts, but does not report outcome analyses from which the primary question can be answered.
9. Statistical Methods Explained
The registry specifies a median and inter-quartile range for the primary satisfaction score. These summaries are suited to describing the center and spread of a set of scores without requiring the score distribution to be symmetric. In general, the median is the middle value after observations are ordered; the inter-quartile range spans the middle half of the observations. Those summaries would describe the recorded operator scores, but the actual values are not reported in the registry record.
What does a single-arm design estimate?
In general, a single-arm study can describe outcomes observed in the participants who received the intervention. It lacks an internal comparison group that could show how outcomes differed under another approach. The registry identifies this study as single-arm and observational, and does not describe a comparator. The record therefore cannot support a randomized or controlled contrast between device use and non-use.
That distinction matters even for descriptive outcomes. A median satisfaction score, if reported, would characterize the scores in this study, but would not by itself quantify how satisfaction would have differed without the device. Likewise, an observed count of arterial punctures would describe the recorded cohort, but would not establish the causal effect of the device on that outcome. These are general interpretations of uncontrolled data; no such primary or secondary outcome values are posted in the registry record.
What would a confidence interval mean?
In general, a confidence interval expresses uncertainty around an estimate under a specified statistical model and sampling process. It helps distinguish a relatively precise estimate from one with substantial uncertainty. A confidence interval is not reported for the primary endpoint or the secondary outcomes in this registry record. Without an estimate and an interval, readers cannot judge the statistical precision of those outcomes from the record.
The same caution applies to p-values. A p-value is a quantity produced by a particular statistical test under its assumptions; it is not an effect size and does not measure clinical importance. No p-values or statistical tests are listed. The registry record does not state a statistical analysis plan that would identify which tests, models, or assumptions were intended.
How should the planning assumptions be read?
The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the target effect is a stated fraction of the observed effect. It also distinguishes planning outputs for time-to-event outcomes, expressed as total events, from other outcomes, expressed as participants per arm. These are general planning assumptions, not a description of the enrolled study’s design or an observed-power calculation.
The enrolled study is described as single-arm, and no like-for-like two-arm comparison is reported. The registry does not report a sample-size justification for the actual study or the observed effect used for the planning illustration. Nor does it report numerical planning outputs in this record. Accordingly, the planning assumptions cannot be read as evidence that the study had a particular power, or that a particular number of participants was adequate for its primary question. Sample-size calculations are planning exercises; they do not establish what the study observed.
Why do model assumptions matter?
Statistical models summarize data by making assumptions about how observations vary and relate to one another. In general, over-dispersion occurs when variability is greater than a chosen model expects. If a model does not account for that extra variability, its uncertainty estimates may be too small. The registry record does not identify a model for the primary or secondary outcomes, so it is not possible to assess whether over-dispersion or other model assumptions were relevant to the sponsor’s analysis.
For outcomes recorded as counts or proportions, the chosen method may depend on the number of observations and the way events are distributed. For a satisfaction score, the summary method may depend on the scale and distribution. These are general methodological considerations, not descriptions of analyses conducted in this study. The registry lists no analyses and does not report enough detail to determine whether any particular model or test was used.
What is the role of recalculation?
A recalculation from posted summary statistics is an unadjusted calculation, not a substitute for a sponsor’s prespecified analysis. No outcome summary statistics or sponsor analysis are reported in this record, so there is no posted primary estimate to recalculate. There is also no sponsor analysis in the registry record to compare against. As a result, no recalculated effect or inference can be stated for this study.
Overall, the statistical information in the registry defines the intended primary summary and mentions generic planning assumptions, but does not provide the outcome data or analysis results needed to evaluate estimates, uncertainty, or model fit. The distinction between a specified method and a reported result is important: naming a median and inter-quartile range does not supply the values, and listing planning assumptions does not establish observed study power or an outcome effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures: operator satisfaction as the primary outcome, plus arterial puncture incidence and an implement used at the time of arterial puncture, if any. Considering multiple outcomes can raise a multiplicity question: when several outcomes are tested, the chance of at least one apparently notable result can increase. As a general statistical practice, a plan may identify one primary outcome, define how secondary outcomes will be interpreted, or adjust for multiple testing. The registry record does not report a multiplicity strategy or a hierarchy for interpreting the secondary outcomes.
No statistical analyses are listed, and results for the named outcomes are not reported in the registry record. It is therefore not possible to determine whether any multiplicity adjustment was used or how the outcome measures were analyzed together. The record does not report a statistical analysis plan.
Missing-data handling is also not reported in the registry record. There is no account of the number of missing satisfaction scores, missing secondary outcome data, reasons for missingness, or any imputation or other handling method. The analysis populations are not described, so it is not clear from the record which enrolled participants, if any, contributed to each outcome summary.
These omissions limit interpretation of both completeness and selection. In general, missing outcomes can affect estimates if the participants with recorded data differ systematically from those without recorded data. Without counts and methods, readers cannot assess that possibility for this study. The registry record also does not explain the difference between the planned enrollment of 40 described in the summary and the reported enrollment of 20, or state how that difference affected the analysis population.
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 |
|---|---|---|---|
| Enrolled Patients | 0 | 20 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Enrolled Patients | 0 of 20 |
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 |
|---|---|
| Enrolled Patients | 0 of 20 |
The safety record lists 20 participants at risk for serious adverse events, with 0 affected; it also lists 20 at risk for other adverse events, with 0 affected. The recorded number of deaths is 0. No top serious adverse-event terms are listed. These are the safety counts recorded for the enrolled-patient group.
These counts should be read as registry entries, not as proof that no adverse events could occur. The record does not provide further detail about how adverse events were defined, monitored, collected, or attributed. It also does not describe follow-up for safety beyond the counts listed. The absence of recorded events in this entry does not establish that risk is absent, particularly when the registry does not describe the collection procedures or provide a comparison group.
The safety figures also do not provide a comparative estimate. The study has one arm, and the registry does not describe a control group. Therefore, the counts cannot show whether event occurrence differed from what would have been observed under another approach. The record reports zero affected participants for the listed categories, but the scope and precision of safety assessment cannot be fully evaluated from the registry record.
12. What the Result Does, and Does Not, Mean
The registry record establishes that the study was registered as a completed, single-arm observational investigation of a transducer used during central venous catheter placement. It describes operator satisfaction as the primary outcome, assessed on a 0–10 scale at 15 minutes, and lists arterial puncture incidence and an implement used at the time of arterial puncture, if any, as secondary outcomes. It also reports enrollment of 20 participants and the listed safety counts.
It does not report the observed primary outcome score or results for the secondary outcomes. There are no listed statistical analyses, effect estimates, confidence intervals, or p-values. Thus, the record does not establish the observed level of operator satisfaction, the frequency of the secondary outcomes, or the precision of any estimate. The primary question is defined but not answered by the results recorded in this entry.
The design also limits what could be concluded from outcome summaries alone. Because no comparator group is described, results among participants receiving the device would not by themselves show how outcomes differed without it. This is a general limitation of a single-arm observational design, not an assertion about the direction or size of any effect in this study.
The difference between the planned enrollment of 40 described in the summary and the recorded enrollment of 20 is not explained. The record does not report participant characteristics, missing-data handling, or analysis populations. These details would be important for judging how complete and broadly interpretable any outcome estimates might be.
The most defensible reading is therefore narrow: the registry describes the intended procedure and outcomes, reports enrollment and safety counts, and marks the study completed, but it does not contain the outcome analyses needed to assess the primary question. Neither a favorable nor an unfavorable conclusion about device performance can be drawn from the missing outcome results.
13. Why This Trial Matters Statistically
This trial is statistically notable because its primary outcome is a subjective score, while its design is single-arm and observational. Operator satisfaction can describe the experience of those performing the procedure, but a score is most informative when its measurement, distribution, and missingness are reported. The registry specifies the scale, assessment time, and intended median-and-inter-quartile-range summary, yet does not report the scores or the number of observations contributing to them.
The absence of a comparator also illustrates the difference between describing an outcome and estimating a treatment contrast. A single-arm summary can characterize participants in the study, but cannot provide an internal estimate of how the same outcome would have differed under a contrasting procedure. That distinction is important when interpreting both subjective measures and event counts.
The record further demonstrates why planned enrollment and actual enrollment need to be distinguished. The summary describes a plan to enroll 40 participants, while the record reports enrollment of 20, without explaining the difference. The registry does not give a sample-size justification for the study or outcome analyses that could clarify the consequences of this enrollment.
Finally, the entry lists three outcomes and safety counts but no statistical analyses. Without outcome estimates and uncertainty measures, readers cannot evaluate the magnitude or precision of the intended findings. The case is a useful reminder that a completed study record can describe a design and its planned measurements without presenting results sufficient for statistical interpretation.
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 direct limitation is that the registry record does not report the primary outcome value. It defines operator satisfaction and its summary method but gives no median or inter-quartile range. Results for the two named secondary outcomes are also not reported, and no analyses are listed. The record therefore does not allow assessment of the study’s stated outcome questions.
The study is single-arm and observational, with no comparator group described. This prevents a like-for-like comparison within the registered design. The allocation method is not stated, and the record does not describe a control procedure. These design features limit causal interpretation even if outcome values were available.
Enrollment differs between two entries: the brief summary describes a plan for 40 participants, while the record reports 20 enrolled. The registry does not explain the difference, state whether recruitment ended early, or describe its implications. Participant characteristics are not reported, so the enrolled group’s composition cannot be assessed against the population described in the summary.
The registry does not report the number of operators, how satisfaction was collected, missing outcome counts, missing-data handling, or analysis populations. It does not provide an analysis plan, multiplicity approach, or sample-size justification for the actual study. The listed planning assumptions do not fill these gaps; they describe an illustration rather than the study’s own design or observed results.
Safety reporting is limited to the listed participant counts and event counts. Definitions, ascertainment methods, and additional follow-up details are not reported in the registry record. These limitations are specific to the information recorded for this trial and restrict both outcome interpretation and evaluation of the completeness of its reporting.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Compass Device CVC Trial — NCT03056859.
- Registry record last updated 2024-06-27; status last verified 2024-06.
- Results first posted 2024-06-27.
- 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
NCT03056859, titled Compass Device CVC Trial, is recorded as a completed, single-arm observational study sponsored by the University of New Mexico. It concerns central venous catheterization in obese patients and use of an extravascular blood pressure transducer. The registry lists a start date of 2017-02-17, primary completion date of 2020-02-10, and enrollment of 20. The brief summary describes a plan to enroll 40 consenting patients with BMI ≥35; the difference between the planned and reported enrollment is not explained.
The primary outcome is operator satisfaction on a 0–10 scale at 15 minutes, intended to be summarized by median and inter-quartile range. Secondary outcomes concern arterial puncture incidence and an implement used at the time of arterial puncture, if any. The record lists 0 serious adverse events among 20 at risk, 0 other adverse events among 20 at risk, and 0 deaths. Outcome results and statistical analyses are not reported in the registry record.