Comparison of the ToFscan and TetraGraph During Recovery of Neuromuscular Function in the Post Anesthesia Care Unit: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of the ToFscan and TetraGraph During Recovery of Neuromuscular Function in the Post Anesthesia Care Unit (NCT03920670), a randomized na study. The primary outcome is Mean Train-of-Four Ratios (TOFR's).

2. Clinical Question

The clinical question concerns measurement performance in the recovery setting, rather than a comparison of different drug treatments. The registry summary explains that the monitors produce objective data using different techniques. It describes the investigation as a comparison of two quantitative monitors used with recovering patients, while the primary outcome specifies the train-of-four ratio as the measure under study.

The randomization applies to the monitor placement configurations recorded for the arms. Since each configuration places one monitor on the dominant hand and the other on the non-dominant hand, the primary outcome focuses on the device placed on the dominant hand. The registry record does not describe the randomization procedure in further detail, nor does it explain how the non-dominant-hand readings were used, if at all, in the analysis.

3. Trial Design

The registry identifies this as a randomized, unmasked, parallel trial. The enrollment field lists 120. The record lists the trial status as completed, with a start date of 2019-02-28 and a primary completion date of 2020-11-30. The phase is recorded as NA. Mayo Clinic is listed as the sponsor.

The two arm descriptions define different hand placements. In the TetraGraph configuration, TetraGraph is on the dominant hand and ToFscan is on the non-dominant hand. In the ToFscan configuration, those placements are reversed. The primary outcome is limited to dominant-arm train-of-four ratios, so the configuration determines which of the two monitors is on the hand used for that endpoint.

Unmasked means the record does not describe masking of the assigned monitor configuration. The registry does not provide further details about who knew the configuration, how assignments were generated or concealed, or whether the people recording or analyzing the measurements were masked. The parallel designation describes the trial model recorded in the registry; it does not, by itself, explain the detailed sequence of observations or the analysis of measurements over time.

The outcome timeframe lists baseline, after 5 minutes, and after + 10 minutes. The registry record does not provide a fuller schedule, such as the interval between baseline and the first follow-up measurement, or a description of procedures at each time point. Although the study summary places the investigation in the post-anesthesia recovery setting, additional setting and participant details are not reported in the registry record.

The record does not report a sample-size justification, the allocation method, or a protocol-level statistical plan. Planning illustrations described for the trial use the observed effect, a two-sided significance level of 0.05, equal allocation between the arms, and a normal approximation. Those illustrations are planning calculations, not evidence of the trial’s observed power or of its original design rationale.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Dominant arm Train-of-Four Ratios collected for analysis

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Mean Train-of-Four Ratios (TOFR's), measured over baseline, after 5 minutes, after + 10 minutes.

The primary endpoint is the mean train-of-four ratio, with standard deviation as the stated measure of dispersion. The ratio is defined in the registry as the fourth muscle response divided by the first muscle response. The outcome is collected from the dominant arm and is listed at baseline, after 5 minutes, and after + 10 minutes.

In general, a quantitative train-of-four ratio expresses the relative size of the fourth response compared with the first response in a sequence of muscle responses. Recording this ratio provides a numerical measure of neuromuscular function during recovery. The registry summary explains that quantitative monitors can provide objective data and describes the study as a comparison of monitors that use different measurement techniques.

Using the mean describes the average recorded ratio for a group at a specified time point. The standard deviation describes how spread out the recorded values are around that group mean. These summaries can help readers distinguish the central measurement from its variability, but neither alone establishes whether measurements from different devices agree closely for individual patients.

The registry record gives no outcome means, standard deviations, confidence intervals, or inferential test results. It therefore does not show the size or direction of any observed difference between the monitor configurations at the listed times. The record also does not define a threshold for interpreting a ratio or state what magnitude of difference would be clinically important.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods describe how observations are turned into estimates and how uncertainty in those estimates is assessed. For this trial, the registry record specifies a continuous primary outcome summarized as a mean and standard deviation, but does not list an analysis method or numerical analysis results. The explanations below describe general statistical concepts and what they would mean for this type of comparison; they are not claims about methods used in the trial.

What does a mean describe?

For a continuous measure, the mean is the arithmetic average of the observed values in a group. Here the measured quantity is the train-of-four ratio from the dominant arm. A mean at a particular time point would summarize the group’s central value at that time. Comparing means can address whether the groups differ on average, provided the comparison and its uncertainty are reported.

A mean does not describe every observation. Different distributions can have the same mean, and observations within a group may vary substantially. The registry names standard deviation as the dispersion measure. In general, standard deviation describes the spread of values around the mean, in the outcome’s units. It is not the same as the standard error, which describes uncertainty in an estimated mean, and it is not a confidence interval.

What does a confidence interval add?

In general, a confidence interval gives a range of values compatible with the data and the statistical procedure used to calculate it. For a difference between group means, the interval conveys both the estimated direction and the precision of that estimated difference. A narrow interval indicates greater precision than a wide interval, considered in relation to the same quantity and method. An interval also helps show whether the data are compatible with effects of different sizes. The registry record does not report confidence intervals for the primary outcome.

A p-value, if reported, would describe how unusual the observed data or more extreme data would be under a specified null hypothesis and statistical model. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of a difference. The registry record does not report a p-value or identify a hypothesis test for the primary outcome.

Why do the time points matter?

The endpoint is recorded at baseline, after 5 minutes, and after + 10 minutes. In general, multiple observations over time can be handled by separate comparisons at each time, by comparing changes from baseline, or by a model that represents the observations jointly. Those approaches answer different questions and may account for within-participant dependence differently. The registry record does not state which approach was used, whether the measurements were modeled jointly, or whether the main contrast was a difference at a particular time or a pattern across times.

Repeated measurements from the same participant are generally related rather than independent. A method that ignores this relationship may estimate uncertainty incorrectly. Appropriate methods can account for the correlation, but the choice depends on the design, data structure, and intended comparison. None of those details are reported for the primary analysis in the registry record, so a reader cannot determine how repeated measurements were handled.

What is the difference between comparison and agreement?

In general, comparing group means asks whether average measurements differ between groups. Agreement methods ask how closely two measurement methods produce values for the same underlying observations, including whether one method tends to read higher or whether differences vary across the measurement range. A strong average association does not necessarily mean close agreement. Because the registry record reports only the endpoint definition and not an analysis method, it does not establish whether the statistical question was framed as a mean comparison, a device-agreement assessment, or both.

How should the planning calculations be read?

The registry describes planning illustrations computed from the observed effect, using a two-sided significance level of 0.05, equal allocation between the arms, and a normal approximation. In general, sample-size planning calculations depend on assumptions about the effect to detect, variability, significance level, and desired power. Changing assumptions changes the planning result. A calculation based on an observed effect is illustrative and should not be treated as a prospective design justification or as observed power. The registry record does not report the original sample-size rationale or the effect and variability assumptions used to plan the trial.

Power is a design concept describing the chance that a specified analysis would detect an effect of a specified size under stated assumptions. After a study is completed, the observed estimate and its uncertainty are more informative about what the data show than a retrospective power calculation. The planning illustrations do not substitute for the missing primary outcome estimates or their confidence intervals.

What can be concluded from the posted analysis record?

The registry lists zero analyses and does not provide numerical results for the primary endpoint. The statistical model, handling of repeated measurements, missing-data approach, analysis population, treatment of outliers, and multiplicity procedures are not reported in the registry record. These details cannot be reconstructed from the endpoint definition or trial design. Without posted estimates and uncertainty measures, no inferential conclusion about the comparison can be made.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is listed at baseline, after 5 minutes, and after + 10 minutes. Examining an outcome at multiple time points can create multiple opportunities for a statistically notable result, depending on the analyses performed. In general, a multiplicity plan specifies which comparisons are primary and how the chance of false-positive findings is handled across them. The registry record does not report such a plan, identify a single primary time-point contrast, or describe any adjustment for multiple comparisons.

The registry record lists no analyses and provides no numerical primary outcome results. It does not report whether the time points were analyzed separately, jointly, or as change from baseline. It also does not describe whether any other outcomes or subgroup analyses were tested. These omissions prevent assessment of how many comparisons were made or how the reported analysis, if any, was selected.

Missing-data methods are not reported in the registry record. The record does not state how many dominant-arm readings were available at each time, how missing measurements were handled, or whether participants with incomplete observations were included in particular analyses. The number analyzed for the primary endpoint is therefore not reported.

The analysis population is not reported in the registry record. The record does not say whether the primary analysis followed randomized assignment regardless of measurement availability or used another population definition. The enrollment field lists 120, and the safety groups each list 115 at risk, but the record does not explain how these entries relate to the primary endpoint population.

These absences do not demonstrate that a particular method was or was not used outside the registry entry. They mean the registry record does not provide enough information to evaluate missing-data handling, multiplicity control, or the definition of the population underlying the primary analysis.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry safety entries list, for each monitor configuration, 115 participants at risk for serious adverse events and 0 affected. They also list 115 at risk for other adverse events and 0 affected. Deaths are listed as 0 in each group, and no top serious-event terms are listed.

These figures describe the safety information recorded in the registry. They do not establish that no events occurred outside the reporting definitions or observation period used for the record. The registry entry does not provide a fuller description of safety surveillance, event definitions, follow-up duration, or how the at-risk counts were determined.

The enrollment field lists 120, whereas the safety entries list 115 at risk in each group. The registry record does not explain the relationship between those figures. They should not be combined or interpreted as a count for the primary outcome analysis. The safety counts also do not provide information about the numerical train-of-four ratio results or comparative monitor performance.

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

The record establishes that the trial was designed to compare two quantitative monitoring configurations during recovery in the post-anesthesia care unit. It identifies a randomized, unmasked, parallel design; defines the dominant-arm train-of-four ratio as the primary outcome; and lists measurements at baseline, after 5 minutes, and after + 10 minutes. It also records zero affected participants for the listed serious and other adverse-event categories in each safety group.

The record does not establish how the monitors compared on the primary endpoint. Numerical means, standard deviations, estimates of between-group differences, confidence intervals, and p-values are not reported in the registry record. Without these results, the direction and size of any observed difference, and the precision of that difference, cannot be assessed.

Even if group means were available, a difference or similarity in averages would not by itself answer every measurement question. In general, device agreement concerns how close readings are for individual observations, while a mean comparison concerns average values. The registry record does not report whether an agreement analysis was conducted.

The record also does not report a clinically important difference threshold or a rule for interpreting train-of-four ratios. It therefore cannot establish whether a numerical difference, if observed, would matter in practice. The summary describes the monitors as using different techniques and notes their potential use in monitoring neuromuscular recovery, but the registry entry does not support a treatment recommendation or a conclusion about patient outcomes.

The safety counts should be interpreted separately from the efficacy endpoint. They are registry-reported counts with no affected participants listed in the specified categories, not evidence about the primary outcome or a complete account of every possible safety question. Overall, the posted information describes the comparison that was planned and some safety entries, but it does not provide the outcome evidence needed to judge comparative measurement results.

13. Why This Trial Matters Statistically

This trial raises a statistical question about quantitative measurement: whether two monitors using different techniques produce comparable dominant-arm train-of-four ratios during recovery. Measurement comparisons are important because the interpretation of an observed value depends not only on the underlying biological state but also on how the instrument records it. The registry summary identifies ToFscan as acceleromyography-based and TetraGraph as electromyography-based, making the distinction between measurement methods central to the study question.

The design also makes hand placement relevant to interpretation. The arm descriptions reverse which monitor is placed on the dominant hand, while the primary outcome is specifically collected from that arm. A reader therefore needs to understand the assigned configuration when interpreting any dominant-arm comparison. The registry provides those configurations but does not explain how non-dominant-arm measurements were used.

Statistically, a comparison of average ratios and an assessment of agreement are not interchangeable. A mean difference can describe systematic separation between groups, while agreement examines how closely methods correspond at the level of individual measurements. Repeated measurements at the listed times add another consideration: estimates and uncertainty need to reflect the time structure and any dependence among observations. The registry record does not report which analyses addressed these questions.

The trial is also a reminder that registration details and posted results serve different purposes. The record supplies the design and endpoint definitions, but without outcome estimates and analysis details it cannot answer the comparative question. The planning illustrations do not replace those results. The safety entries provide a separate descriptive account, not an estimate of measurement agreement or efficacy.

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 main limitation for interpretation is that the registry record does not report numerical primary outcome results or statistical analyses. It therefore does not permit assessment of the size, direction, or precision of the comparison between monitor configurations. The primary outcome is specified at multiple times, but no time-specific estimates or overall longitudinal analysis are described.

The record does not report how repeated measurements were handled, how missing values were treated, or which participants were included in the primary analysis. It also does not describe multiplicity control, an agreement analysis, or a threshold for clinical importance. These omissions limit evaluation of both the statistical validity and practical interpretation of any comparison.

The randomized, unmasked, parallel design is recorded, but the registry does not provide details about the allocation procedure, concealment, or masking of measurement and analysis personnel. The arm descriptions indicate that the devices are placed on opposite hands and that the primary outcome uses the dominant arm, but the record does not explain the role of the non-dominant-hand readings.

The enrollment field lists 120, while the safety entries list 115 at risk in each group. The registry record does not explain this difference or link the safety counts to the primary analysis population. The safety record also provides limited detail about event definitions and observation procedures. These limitations concern what can be learned from the registry record and do not establish that unreported procedures or analyses were absent from the trial itself.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of the ToFscan and TetraGraph During Recovery of Neuromuscular Function in the Post Anesthesia Care Unit — NCT03920670.
• Registry record last updated 2021-04-29; status last verified 2021-03.
• Results first posted 2021-04-29.
• 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.

18. Record Summary

NCT03920670 is a completed randomized, unmasked, parallel trial sponsored by Mayo Clinic. Its registry record lists enrollment of 120, a start date of 2019-02-28, and a primary completion date of 2020-11-30. It compares configurations in which either TetraGraph or ToFscan is placed on the dominant hand, with the other monitor on the non-dominant hand.

The primary outcome is the mean dominant-arm train-of-four ratio, with standard deviation, recorded at baseline, after 5 minutes, and after + 10 minutes. The registry defines the ratio as the fourth muscle response divided by the first. Numerical outcome results and statistical analyses are not reported in the registry record.

Safety entries list 115 at risk in each group, with 0 affected for serious adverse events, 0 affected for other adverse events, and 0 deaths. The relationship between these safety counts and the enrollment field is not explained.