Clinical Performance of Masimo INVSENSOR00040: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Performance of Masimo INVSENSOR00040 (NCT05332392), a na na study. The primary outcome is Oxygen Saturation (SpO2) Accuracy of INVSENSOR00040.

2. Clinical Question

This is a measurement-performance question, not a comparison of treatment outcomes. The device reading and the reference measurement are intended to characterize agreement in oxygen saturation. The registry describes a controlled desaturation procedure in which the oxygen concentration participants inhale is slowly reduced until arterial oxygen concentration is approximately 70%. Arterial blood samples are collected during the procedure.

The primary outcome is titled “Oxygen Saturation (SpO2) Accuracy of INVSENSOR00040.” Its description says performance is assessed using an ARMS value, based on comparison of noninvasive SpO2 measurements with SaO2 from a reference blood sample. The endpoint timeframe is 1-5 hours. However, the registry record does not report the resulting ARMS value, its uncertainty, or the number of observations contributing to the endpoint. Consequently, the clinical question is identifiable, but the posted record does not provide the primary result needed to judge the observed level of agreement.

3. Trial Design

The registry identifies this as a completed, single-group device study sponsored by Masimo Corporation. The intervention is INVSENSOR00040, a noninvasive device. Allocation is listed as NA and masking as none. This is not a randomized comparison, and the record does not describe a separate control arm for a like-for-like comparison.

The listed condition is Healthy. The brief summary describes a controlled desaturation procedure, with inhaled oxygen gradually reduced and arterial samples collected. The stated purpose is to compare noninvasive oxygen-saturation measurements with reference values from a laboratory blood gas analyzer. Pulse-rate measurements are also described as being compared with a standard-of-care EKG monitor. The primary outcome record, however, gives details only for the oxygen-saturation accuracy assessment.

The registry lists enrollment of 90 and a study start date of 2022-04-14. Primary completion is listed as 2023-04-13, and status is COMPLETED. These record fields describe enrollment and study timing; they do not establish how many participants contributed usable primary-endpoint data. The outcome description notes that data from 13 subjects were excluded because of desaturation procedural error. It also notes exclusions for missing data with noise interference and for discomfort, but does not give a final analyzed sample size.

The registry record does not report a detailed statistical analysis plan, a protocol-based sample-size justification, or the handling of any interim analyses. The posted planning illustrations use assumptions for a hypothetical equal-allocation, two-arm comparison, while this study is identified as single-group. Such planning outputs should not be read as evidence of the trial's design or as observed power.

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: Data from 13 subjects was excluded due to desaturation procedural error. Data from 1 subject was excluded due to missing data and evidence of noise interference that did not allow for the comparison of the dataset. Data from 1 subject was excluded because the subject complained of discomfort at the early part of the desaturation procedure and therefore was unable to desaturate to below 90% SaO2.

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 Oxygen Saturation (SpO2) Accuracy of INVSENSOR00040, measured over 1-5 hours.

The primary endpoint assesses oxygen-saturation accuracy for INVSENSOR00040. Noninvasive SpO2 readings are compared with SaO2 values from arterial reference samples, over the stated desaturation range of 70-100%. The timeframe is 1-5 hours. The registry describes the summary measure as ARMS, computed as the square root of the sum of the squares of bias and precision.

In general, bias describes systematic departure of measurements from a reference, while precision describes the spread of measurement errors. Combining these components gives an overall measure of error magnitude: it reflects both consistent offset and variation around the reference. It is useful for evaluating agreement because a correlation alone can be high even when measurements differ systematically from the reference.

ARMS is not, by itself, a complete account of performance at every saturation level or for every participant. Its interpretation depends on the observations included and the range over which it was calculated. The registry record does not report the ARMS result, a confidence interval, or additional detail on the distribution of errors. It therefore does not establish the magnitude or precision of the observed endpoint estimate.

The brief study summary also mentions pulse-rate comparison with an EKG monitor, but the primary endpoint described in the record concerns oxygen saturation. The record does not report a pulse-rate result in the registry record for this analysis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does ARMS summarize?

The registry describes ARMS as the square root of the sum of the squares of bias and precision. In general, bias captures a tendency for measurements to sit consistently above or below a reference, while precision captures the variation of errors around that tendency. A combined error summary can therefore reflect both systematic offset and scatter. The registry record does not report the calculated ARMS value for INVSENSOR00040, so the method is described but its study result cannot be interpreted quantitatively.

Why compare with a reference?

For a measurement device, the central question is whether its readings agree sufficiently with a reference method. The record identifies arterial oxygen saturation from a reference blood sample as the comparator for noninvasive SpO2. This is different from asking whether two measurements move together. In general, measures can track each other while still differing systematically, so agreement and correlation answer different questions. The registry describes a reference comparison, but does not report the observations or estimate needed to evaluate the agreement.

What does the desaturation range contribute?

The stated range for accuracy is 70-100%. The controlled procedure is described as gradually reducing inhaled oxygen until arterial oxygen concentration is approximately 70%. In general, evaluating measurements across a range helps examine performance under differing measurement conditions rather than at a single level. A single overall summary may nevertheless conceal variation across that range. The record does not report results by saturation level, the distribution of measurements across the range, or separate estimates within any part of it.

How should uncertainty be read?

A confidence interval is a statistical range used to express uncertainty around an estimate. In general, a narrower interval indicates greater precision under the assumptions of the analysis, while a wider interval indicates more uncertainty. It does not describe the full range of individual measurement errors. The registry record does not report a confidence interval for ARMS or another uncertainty estimate. Accordingly, neither the central accuracy estimate nor its precision can be assessed from the posted record.

For measurement studies, it is also useful to distinguish an overall summary from the pattern of errors. General agreement methods may examine the average signed difference, the spread of differences, and whether error changes with the magnitude of the measurement. These approaches answer related but nonidentical questions. The registry outcome description specifies ARMS, but does not state that these additional analyses were conducted or report their results. They should not be assumed to have been part of the study's analysis.

What can exclusions change?

Analysis populations matter because the endpoint depends on paired device and reference measurements. The primary outcome description says that data from 13 subjects were excluded for desaturation procedural error. It further describes an exclusion due to missing data and noise interference that prevented comparison, and an exclusion due to discomfort. The registry record does not report whether exclusions were defined before data collection, whether additional data were unavailable, or how the final analysis set was formed.

In general, excluding observations can affect both the estimate and its uncertainty, particularly if excluded data differ systematically from retained data. That possibility is not evidence that the estimate is biased in this study; the available record does not provide enough detail to assess it. The appropriate reading is that exclusions are documented, while their impact on the reported endpoint cannot be evaluated because the endpoint result and analysis population are not reported.

What are the planning calculations?

Sample-size calculations are planning tools that describe the amount of information a future study might need under stated assumptions. The posted planning framework specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes planning for stated fractions of an observed effect. These are not the design characteristics of the registry's single-group study and are not observed power.

Observed power is not a substitute for an estimate and its uncertainty. Planning illustrations can be useful for considering hypothetical future designs, but they cannot show that this study met an accuracy criterion or produced a precise estimate. The registry record does not report the primary ARMS result on which the illustrations are said to be based, nor does it report a protocol-based sample-size justification. The illustrations therefore do not fill the gap in the posted endpoint results.

The registry lists two outcome measures and zero analyses. The record does not report a detailed statistical analysis plan, methods for handling repeated measurements, or a prespecified approach to missing data. No unreported modeling choices or inferential procedures should be inferred from the endpoint definition alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures, but records zero analyses. The primary endpoint description concerns oxygen-saturation accuracy; the brief summary also describes a pulse-rate comparison, but the registry record does not report a pulse-rate result in the registry record. A detailed statistical analysis plan, including any hierarchy of outcomes or adjustment for multiple testing, is not reported in the registry record.

Multiplicity refers generally to the interpretive issue that arises when multiple outcomes or statistical tests are considered. Without a reported analysis plan and outcome results, it is not possible to determine whether multiplicity adjustments were used or how any such adjustments would affect interpretation. No adjustment should be assumed.

The outcome description documents exclusions from the oxygen-saturation data: 13 subjects for desaturation procedural error, one for missing data and noise interference that prevented comparison, and one because of discomfort. The registry record does not report the final analysis population, additional missingness, or a full account of how missing observations were handled. It also does not describe an intention-to-measure population or another prespecified analysis set. The available information is therefore insufficient to determine whether the reported endpoint, if any, would represent all enrolled participants or only those with usable paired data.

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.

Most frequent non-serious adverse event terms

The registry lists adverse-event figures for the INVSENSOR00040 group. It records 0 participants with serious adverse events among 46 at risk for serious events, and 4 participants with other adverse events among 46 at risk for other events. The record lists no serious adverse-event terms.

These counts should be read as the registry's reported event summaries, not as a complete description of event type, timing, severity, or relationship to the device. The record does not provide further detail about the four other events in the registry record for this analysis. Nor does it describe how adverse events were collected or define the follow-up period for these figures.

The listed at-risk groups are not interchangeable with the enrollment figure or with the primary endpoint analysis population. The registry record does not explain the relationship between the safety denominators and the participants contributing to the oxygen-saturation outcome. These figures therefore address only the adverse-event counts as recorded and do not resolve the missing primary accuracy result.

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

The record establishes that the study evaluated noninvasive oxygen-saturation measurement against arterial reference values during a controlled desaturation procedure. It also defines the endpoint as an ARMS summary across 70-100%. These details clarify the intended measurement question and the reference used.

The record does not report the ARMS result, a confidence interval, or the final analysis population. It therefore does not show the observed accuracy or how precisely it was estimated. Although the study status is COMPLETED, completion status is not a substitute for a posted endpoint result. Readers cannot determine from these registry entries whether the observed measurement error was small or large, or whether the estimate was sufficiently precise for a particular use.

Nor does this record establish that the device changes health outcomes, is better than another device, or meets a specific performance threshold. The design is single-group and the primary endpoint is a comparison with a reference measurement. The registry record does not report a prespecified acceptance threshold or results from a randomized comparison.

The documented exclusions show that not all collected data necessarily contributed to the primary outcome. Their impact cannot be determined because the final analysis set and endpoint estimate are not reported. The planning illustrations are hypothetical and should not be interpreted as observed power or evidence of accuracy. In short, the record describes the study's measurement objective and some design and safety details, but leaves the primary quantitative result unreported.

13. Why This Trial Matters Statistically

Device-performance studies depend on a clearly defined reference and a measure that reflects agreement, not merely association. This study's registry description identifies arterial oxygen saturation as the reference for noninvasive SpO2 and names ARMS as the primary summary. That makes the target measurement question understandable to readers assessing how such a device evaluation is framed.

The controlled desaturation procedure and stated 70-100% range also make the measurement context explicit. In general, a device's performance may vary across measurement conditions, so the range and the distribution of observations matter when interpreting a single summary. The registry record does not report results across the range, however, and this limits what can be learned about the pattern of performance.

The record also illustrates why the endpoint estimate, uncertainty, and analysis population are all important. Exclusions are described, but the final population and ARMS result are not reported. Without those elements, it is not possible to judge either the magnitude of measurement error or the precision of the estimate. Planning calculations cannot replace those results.

Statistically, the study's value as a measurement evaluation depends on transparent reporting of paired data, the analysis population, and uncertainty around the agreement summary. The registry record supplies the broad endpoint definition and procedural context, but not the quantitative result required for a full 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 principal limitation of the registry record for interpretation is that it does not report the primary ARMS result or its uncertainty. The number of participants in the final oxygen-saturation analysis is also not reported. Consequently, the magnitude and precision of the measured accuracy cannot be evaluated.

The outcome description reports exclusions for procedural error, missing data with noise interference, and discomfort. It does not provide a complete account of missing observations, the final analysis population, or the effect of exclusions on the endpoint. It also does not report accuracy estimates across the stated 70-100% range.

The study is single-group, with allocation listed as NA and masking listed as none. It does not provide a randomized, like-for-like control comparison. The registry record does not report a prespecified performance threshold, a detailed statistical analysis plan, or a protocol-based sample-size justification. It also does not report a pulse-rate result, although pulse-rate comparison appears in the study summary.

Finally, the safety information is limited to participant counts and does not describe event details or collection procedures. These limits concern what can be interpreted from the registry record; they do not establish that unreported analyses or results were absent outside the record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Performance of Masimo INVSENSOR00040 — NCT05332392.
• Registry record last updated 2024-06-11; status last verified 2024-01.
• Results first posted 2024-02-28.
• 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

NCT05332392 is a completed, single-group study of the INVSENSOR00040 noninvasive device in healthy participants. Masimo Corporation is listed as sponsor. The registry records enrollment of 90, a start date of 2022-04-14, and primary completion on 2023-04-13.

The primary outcome is oxygen-saturation accuracy, assessed by comparing device SpO2 with arterial SaO2 and summarizing error with ARMS across 70-100%. The description documents exclusions for desaturation procedural error, missing data with noise interference, and discomfort. The final analysis population and primary endpoint result are not reported in the registry record.

Safety figures list 0 serious adverse events among 46 at risk and 4 other adverse events among 46 at risk. The record does not provide further event details in the information available for interpretation.