Repeatability and Reproducibility of Oxygen Reserve Index (ORi): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Repeatability and Reproducibility of Oxygen Reserve Index (ORi) (NCT05636098), a na na study. The primary outcome is Repeatability of Masimo Rainbow Sensors.

2. Clinical Question

The study focuses on measurement performance rather than a comparison of treatments or clinical outcomes. ORi is described as a unitless parameter ranging from 0-1, with 0 indicating normoxia and 1 indicating moderate to high hyperoxia. The protocol uses controlled hyperoxygenation so that readings can be considered across conditions relevant to the sensor’s measurement behavior. The record does not provide an estimate of repeatability, its precision, or the underlying readings. As a result, the stated question and endpoint definition can be described, but the magnitude and uncertainty of the observed repeatability cannot be assessed from the registry record.

3. Trial Design

This is a completed, single-group device study sponsored by Masimo Corporation. Its registered title is “Repeatability and Reproducibility of Oxygen Reserve Index (ORi).” The record lists the study population as healthy and enrollment as 53. Participants received noninvasive Masimo Rainbow Sensors while undergoing a controlled hyperoxygenation protocol. The study description names an investigational Masimo rainbow sensor and FDA-cleared rainbow sensors connected to a Masimo Radical-7 pulse oximeter and Masimo Root monitor.

The registry lists allocation as not applicable and masking as none. It describes the model as single-group, so there is no independent control arm or randomized treatment contrast to interpret. The study evaluates measurement consistency under similar operating conditions, with repeated readings and sensor-related comparisons described in the endpoint definition. The record does not report a protocol-level account of how readings were ordered, how many readings were obtained, or how conditions were assigned.

The start date is 2022-11-07, and primary completion is listed as 2023-01-11. The status is completed. The primary outcome is repeatability of Masimo Rainbow Sensors, measured as mean absolute error with a full range, over a timeframe of 1-1.5 hours. The record states that 2 subjects were excluded from the primary analysis because of device setting errors. It does not report the primary endpoint’s numerical result or a detailed analysis plan. Although reproducibility appears in the study title, the registry record’s specified primary outcome is repeatability; a separate numerical reproducibility result is 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

Analysis population for the primary outcome, as defined in the registry: 2 subjects not included in analysis for device setting errors.

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 Repeatability of Masimo Rainbow Sensors, measured over 1-1.5 hours.

The primary endpoint is the repeatability of ORi readings from Masimo Rainbow Sensors. The registry defines a repeatability error as the difference between ORi measurements from one sensor at different time points under similar operating conditions. It then defines repeatability as the mean of the absolute values of those errors across different conditions and sensors. The measure is unitless, consistent with the unitless ORi parameter.

Taking absolute values means that deviations in either direction contribute to the error magnitude rather than canceling one another. Averaging these absolute errors provides a summary of how far repeated readings tend to differ under the conditions assessed. A smaller mean absolute error would indicate closer agreement between those repeated readings in the study setting; this is a general interpretation of the measure, not a reported result for this study.

Repeatability is useful because measurement consistency is a property of the instrument and measurement process, distinct from whether a measurement predicts or changes a clinical outcome. The endpoint’s timeframe is 1-1.5 hours, and its reported dispersion format is full range. The registry record does not give the endpoint value, the range observed, or an uncertainty interval, so the degree of repeatability cannot be quantified from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a mean absolute error. In general, an error is a difference between a measurement and a comparison measurement or value. In this study’s definition, the comparison is between ORi measurements from the same sensor at different time points under similar operating conditions. The endpoint takes the absolute value of each such error and averages those absolute errors across different conditions and sensors. Absolute values prevent positive and negative deviations from canceling in the average, so the summary reflects the magnitude of disagreement.

What does repeatability describe?

As a general statistical concept, repeatability concerns how closely repeated measurements agree when measurement conditions are similar. It is distinct from reproducibility, which generally concerns agreement when relevant measurement conditions vary, such as instruments, operators, or settings. The registry title mentions both repeatability and reproducibility, but its specified primary endpoint concerns repeatability. A separate reproducibility estimate is not reported in the registry record.

The endpoint description refers to readings from a sensor at different time points, and to errors across different conditions and sensors. The record does not give the number or timing of readings, the exact set of conditions, or the method for combining sensor-level summaries. Those details matter because different choices about which repeated pairs are included and how they are weighted can affect an overall mean absolute error. They cannot be inferred from the endpoint definition alone.

How should the unit and scale be read?

ORi is unitless and is described as ranging from 0-1, with 0 indicating normoxia and 1 indicating moderate to high hyperoxia. The repeatability endpoint is also unitless. A mean absolute error is not a percentage unless a percentage scale is explicitly defined; the registry does not define the endpoint as a percentage. A reader should therefore interpret it as an absolute difference on the stated unitless measurement scale, not convert it to another scale.

The registry gives the dispersion format as full range. Generally, a range describes the span from the smallest to the largest observed value in the relevant set. It can show the extremes but does not, by itself, show how densely observations cluster within that span. The actual range is not reported in the registry record.

What would an uncertainty interval add?

In general, a confidence interval is a range of values compatible with the data under a specified statistical procedure and its assumptions. It communicates uncertainty around an estimate; it is not a guarantee that a particular interval contains the true value. The registry record does not report a confidence interval for the primary endpoint. It also does not report the underlying observations needed to assess the estimate’s precision independently.

Repeated measurements from the same person or sensor are often correlated rather than independent. In general, analyses that treat correlated readings as independent can understate uncertainty, because they count related information as if it were separate information. A suitable analysis may need to account for clustering or repeated-measure structure. The registry does not report whether or how such dependence was modeled, so no specific method should be attributed to this study.

What is not specified about the analysis?

The record lists 2 outcome measures and 0 analyses, but does not supply a detailed statistical analysis plan. It does not report a target difference, a sample-size justification, an interim analysis plan, a model for repeated observations, a missing-data method, or a procedure for handling multiple outcomes. These items are not reported in the registry record. Their absence means the analytic choices cannot be evaluated from this record, not that a particular method was or was not used outside it.

The record also says that 2 subjects were not included in the primary analysis because of device setting errors. This identifies a specific exclusion reason, but does not describe whether any readings were removed, how the error was defined, or whether alternative analyses were performed. No recalculated result is available because the endpoint summary statistics are not reported.

Planning calculations, when presented, answer a different question from the observed study result. In general, a sample-size illustration based on an observed effect describes the planning implications of assumed effects and design conditions; it is not observed power and is not a substitute for an uncertainty interval around the study estimate. The registry gives planning assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation for an effect specified as a fraction of the observed effect. Those assumptions describe an illustration, not the registered single-group study design. The registry record does not report the resulting sample-size values or an analysis that makes those two-arm assumptions applicable to the primary endpoint.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and 0 analyses. It supplies a definition for the primary repeatability endpoint, but does not provide a numerical result for it. The other outcome measure’s details and result are not reported in the registry record. No analysis records are listed, and the statistical plan is not reported in the registry record.

Multiplicity arises when multiple outcomes, time points, subgroups, or statistical tests are examined. As a general principle, conducting many tests can increase the chance of at least one apparently notable result when all null hypotheses are true. Statistical plans may address this through a prespecified outcome hierarchy or an adjustment procedure. The registry does not report whether either approach was used. The number of registered outcome measures alone does not establish how many analyses were conducted.

The endpoint description mentions different conditions and sensors, but the record does not state whether separate condition- or sensor-specific estimates were planned or tested. It does not report a multiplicity adjustment, a prespecified testing order, or how any secondary analyses were handled. These details should be treated as not reported in the registry record, rather than assumed to have been omitted from the study itself.

For missing data and analysis populations, the registry states that 2 subjects were not included in the primary analysis because of device setting errors. It does not describe other missing readings, define a broader analysis population, or report an approach to missing-data handling. It also does not provide sensitivity analyses assessing the effect of exclusions. Enrollment is listed as 53, but an analysis denominator should not be reconstructed from the enrollment and exclusion statements. The record does not report whether analyses used participant-level, sensor-level, or reading-level data as the principal unit of 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 lists 53 participants at risk for both serious and other adverse events in the Masimo Rainbow Sensors group. It records 0 serious adverse events, 0 other adverse events, and 0 deaths. These are the posted event counts for this group in the registry record.

Zero recorded events means that the registry reports no events in those categories for the listed group. It does not establish that the underlying risk is zero. In general, an absence of recorded events can be interpreted only in the context of the number observed, the observation period, how events were defined, and how completely they were collected. The record gives a primary endpoint timeframe of 1-1.5 hours, but does not specify the adverse-event observation window or provide additional event-collection details.

The record does not list serious adverse-event terms, consistent with the reported count of 0 serious events. Safety counts are descriptive and do not provide a randomized comparison, since the study is single-group. They should not be interpreted as evidence comparing the sensors with another device or as a comprehensive estimate of risk in populations beyond the healthy volunteers described in the study.

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

The study record documents a measurement-performance question: whether ORi readings from Masimo Rainbow Sensors are consistent when obtained at different time points under similar operating conditions during controlled hyperoxygenation. It defines the primary endpoint as the mean of absolute repeatability errors across different conditions and sensors. This endpoint is relevant to measurement consistency because it summarizes the size of differences between repeated readings without allowing deviations in opposite directions to cancel.

The record does not report the observed endpoint estimate, the full range, or an interval describing uncertainty. It therefore does not show how large the repeatability errors were or how precisely they were estimated. It also does not provide enough information to independently evaluate the reading-level variability or the effects of the stated exclusions.

The study does not test whether a treatment improves a health outcome. It is a single-group device study in healthy volunteers, and there is no randomized comparator. The endpoint is about consistency, not the clinical benefit of using a sensor. A repeatability estimate, even if available, would not by itself establish accuracy against a reference, performance in every clinical setting, or an effect on patient outcomes.

The registry title includes reproducibility, but the specified primary outcome is repeatability. A separate reproducibility result is not reported in the registry record. The stated exclusion of 2 subjects due to device setting errors is relevant to understanding the analysis, but the record does not report sensitivity analyses or explain how the exclusions changed the estimate.

In short, the registry makes the intended question and outcome definition clear, and it reports adverse-event counts. It does not report the numerical primary outcome needed to judge the observed repeatability. Conclusions about the magnitude, precision, or broader applicability of measurement performance cannot be drawn from the registry record alone.

13. Why This Trial Matters Statistically

Measurement consistency is an important statistical property because conclusions based on measurements depend partly on how stable those measurements are under similar conditions. A repeatability assessment asks whether the same measurement process produces similar readings when the conditions are intended to be similar. The endpoint in this study operationalizes that question through absolute differences between ORi readings taken at different time points.

This study also illustrates why a clear endpoint definition is not the same as a complete statistical result. The registry explains what counts as a repeatability error and how those errors are summarized, but does not report the resulting mean absolute error or full range. Without the estimate and information about its uncertainty, readers cannot assess the observed magnitude or distinguish a tightly estimated result from one with substantial variability.

The distinction between repeatability and reproducibility matters in device evaluation. Repeatability focuses on consistency under similar operating conditions, while reproducibility generally asks how measurements compare when conditions vary. The title names both concepts, but the registered primary endpoint is specifically repeatability. A separate numerical reproducibility result is not reported in the registry record.

The record further shows why population and design shape interpretation. This is a single-group study in healthy volunteers undergoing controlled hyperoxygenation, rather than a randomized comparison or an outcome trial. It can frame a sensor measurement question, but cannot establish comparative clinical effects. The explicit note about device setting errors also highlights the importance of documenting exclusions and their implications for the analysis population.

For statisticians and clinical researchers, the study is a useful example of separating endpoint construction, observed results, precision, and generalizability. Here, the endpoint construction and broad study setting are stated, while the numerical endpoint result and important analysis details are not reported in the registry record.

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 important limitation for interpreting the registered findings is that the numerical primary endpoint result is not reported in the registry record. The endpoint is defined, but neither the mean absolute error nor its full range is available. No interval estimate or underlying measurement data are reported, limiting assessment of magnitude and precision.

The record says that 2 subjects were not included in the primary analysis because of device setting errors. It does not describe the errors in detail, report the analysis denominator, or state whether sensitivity analyses were performed. Other missing readings and the approach to missing data are not reported in the registry record.

Further analytic detail is limited. The record does not specify the number and timing of repeated readings, the exact conditions used, how sensor-specific measurements were combined, or whether correlation among repeated observations was accounted for. A statistical analysis plan, sample-size justification for the primary endpoint, interim analysis plan, and multiplicity procedure are not reported in the registry record.

The study is single-group and unmasked, with no randomized comparator. Its setting is healthy volunteers undergoing controlled hyperoxygenation, as described in the registry. This limits the scope of what the design can establish and does not support a randomized comparison or a conclusion about clinical outcomes. Although the title includes reproducibility, a distinct reproducibility endpoint result is not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Repeatability and Reproducibility of Oxygen Reserve Index (ORi) — NCT05636098.
• Registry record last updated 2025-04-06; status last verified 2025-03.
• Results first posted 2025-04-06.
• 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

NCT05636098 is a completed, single-group study sponsored by Masimo Corporation, with enrollment listed as 53. It evaluates repeatability of Oxygen Reserve Index readings from Masimo Rainbow Sensors in healthy volunteers during a controlled hyperoxygenation protocol. The registered primary endpoint is mean absolute error, unitless, with full range reported as the dispersion format and a timeframe of 1-1.5 hours.

The record states that 2 subjects were not included in the primary analysis because of device setting errors. It lists 0 serious adverse events, 0 other adverse events, and 0 deaths. The primary endpoint’s numerical result, uncertainty estimate, and detailed statistical analysis plan are not reported in the registry record. The registry title includes reproducibility, but a separate reproducibility result is not reported.