Evaluation of Objective Pain Measurement Device: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Objective Pain Measurement Device (NCT03975660), a na na study. The primary outcome is Average Self-report Pain Score.

2. Clinical Question

The study's central question is about measurement and association, not a randomized comparison of treatments. The registry summary says investigators intended to compare the device's readings with patient verbal pain ratings and analgesia requirements during routine clinical care. It also describes concurrent brain oxygenation and hemodynamic monitoring. These aims describe what the investigators sought to examine; they do not establish that the relationships were measured successfully or that any association was found.

The primary outcome is average patient self-reported pain on a 0 to 10 scale, with higher scores corresponding to more pain. The stated timeframe is during labor up to 2 hours after epidural. The posted record does not report the observed average, its variability, the number of observations contributing to it, or the results of comparisons or correlations. Those findings are not reported in the registry record.

3. Trial Design

The registry describes a completed study titled “Evaluation of Objective Pain Measurement Device,” sponsored by Stanford University. Its listed start date is 2019-11-01, and its primary completion date is 2023-10-31. The phase is listed as NA. The study model is single group, and allocation is listed as NA. Masking is listed as none. The record lists an enrollment of 130.

The listed group is “Device Calibration and Validation.” Its description says that patients requesting epidural labor analgesia will have pain levels monitored during labor. The intervention is a device called “Pain Measurement Device,” categorized as a device. In the brief summary, investigators describe using the CereVu ROPA device to obtain an objective pain measure, while also monitoring brain oxygenation and hemodynamics with an Edwards Foresight device. The stated setting is routine clinical care.

This is not a randomized two-group design. The registry does not identify a separate control arm, randomized allocation, or masked assessment. The study aim, as described in the summary, is to relate device measurements to patient-reported pain and analgesia requirements, and to explore their relationship with brain oxygenation and hemodynamic changes. Without a listed comparator group, the design does not support a like-for-like treatment comparison.

The record lists 19 outcome measures and no analyses. It names secondary outcomes involving time to reach a pain score of 2 or less out of 10, time for the device score to fall below a validated value, patient-reported and device-recorded pain scores after a block, sensory blockade level, block failures, and maternal and fetal side effects. The registry record does not report numerical results for these outcomes or describe the analysis methods used to evaluate them. The protocol details, including any planned statistical analysis, 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

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 Average Self-report Pain Score, measured over During labor up to 2 hours after epidural.

The primary endpoint is the average self-reported pain score during labor up to 2 hours after epidural. It is defined as a mean on a 0 to 10 scale, with higher values corresponding to more pain; the listed measure of dispersion is the standard deviation. This outcome captures the patient's own assessment, which the study summary identifies as a reference for evaluating the device's objective pain measure.

Using an average can describe the overall level of reported pain across the observations included in the analysis. The standard deviation describes how spread out those scores are around the mean. These statistics answer different questions: the mean describes a central level, while the standard deviation describes variability. Neither alone describes how closely individual device readings correspond to individual patient reports.

The stated timeframe places measurement during labor and extends up to 2 hours after epidural. The record does not give further detail about the exact timing or frequency of individual measurements, how repeated scores were combined, or how missing readings were handled. Those details are not reported in the registry record.

No observed mean, standard deviation, confidence interval, or analysis result for the primary endpoint is reported in the registry record. Consequently, the endpoint definition identifies what was intended to be measured, but the posted record does not establish the observed pain-score distribution or the precision of any estimate. It also does not report a numerical estimate of agreement or association between the self-reported score and the device measure.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome summarized by a mean and standard deviation. General statistical context: a mean is the arithmetic average of measured values, and the standard deviation describes the spread of values around that average. Together, these summaries can describe the center and variability of patient-reported pain scores. They do not show the full distribution, reveal whether observations are clustered within patients, or establish a relationship between two different measurement methods.

What can a mean tell the reader?

A mean summarizes the values used in its calculation. Its interpretation depends on which observations were included and how measurements were collected. In a study that records pain during labor and after epidural, timing may matter because scores can change over time. The registry names a timeframe of during labor up to 2 hours after epidural, but does not report the detailed schedule, the method used to combine repeated scores, or the number of observations contributing to the mean. Those analysis details are not reported in the registry record.

General statistical context: a confidence interval, when reported, gives a range of values compatible with the data and the method used to calculate it. It conveys uncertainty in an estimate; it is not a guarantee that the true value lies within the interval. The registry record does not report a confidence interval for the primary outcome or for a device-versus-patient measurement relationship. Precision therefore cannot be assessed from the posted results.

How should device validation be assessed?

The summary describes an aim to correlate the CereVu ROPA device's objective pain measure with patient verbal pain ratings and analgesia requirements. General statistical context: correlation measures the direction and strength of a pattern in which two variables vary together. A high correlation does not necessarily mean that two measurement methods return similar values. For example, measures may move together but differ systematically in their levels. Agreement analyses examine the size and pattern of differences between methods; calibration examines how the device's output corresponds to a reference measure across its range.

The registry record does not state which correlation, agreement, or calibration methods were used, and it reports no numerical results for them. It also does not identify a validated reference standard beyond the stated comparison with patient-reported pain. The secondary-outcome title “Time Taken for Pain Device Score to Be Below Validated Value” refers to a validated value, but the registry record does not describe how that value was established. The purpose and statistical properties of that threshold are therefore not reported in the registry record.

Why does the study structure matter?

The model is single group, allocation is NA, and masking is none. General statistical context: random allocation can help balance measured and unmeasured factors across comparison groups, while masking can reduce some forms of assessment or reporting influence. Those protections are not described as features of this study. A single-group measurement study can examine recorded patterns within the studied group, but it does not by itself provide a randomized contrast against a control group.

The study summary describes concurrent brain oxygenation and hemodynamic monitoring. General statistical context: when several measurements are collected over time, observations from the same person may be related rather than independent. Analyses that treat related observations as independent can understate uncertainty. Methods for repeated or clustered measurements account for that dependence. The registry record does not report whether measurements were repeated, how they were modeled, or how within-person dependence was handled.

General statistical context: over-dispersion occurs when observed variability is greater than assumed by a statistical model. It matters because standard errors and confidence intervals can be too small if a model understates variability. Whether over-dispersion is relevant depends on the outcome and model. The registry does not report its analysis model, so no claim can be made about whether over-dispersion was assessed or present in this study.

What do planning calculations represent?

The registry includes assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with effects described as fractions of the observed effect. It also notes that time-to-event illustrations use a total event count, while other illustrations use participants per arm. These are planning assumptions, not the listed study design. The study itself is registered as single group, not as a two-arm randomized comparison. The planning assumptions should therefore not be read as evidence that the trial enrolled two arms or used those methods in its own analysis.

General statistical context: sample-size calculations depend on the target effect, variability, allocation, significance level, and statistical model. A planning illustration describes how a hypothetical future design might be sized under stated assumptions. It is not observed power and does not establish the precision of the actual study results. The record does not report the trial's own sample-size justification, or a target effect and variability used to plan enrollment. Those details are not reported in the registry record.

The record lists no analyses and gives no primary-outcome estimate, statistical test, confidence interval, or model specification. Thus, statistical methods can be explained in general, but the methods actually used to analyze this study's outcomes are not reported in the registry record.

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.

R code and output

arm <- c("Device Calibration and Validation")
n   <- c(130)
m   <- c(4.08)
sp  <- c(3.33)
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  Device Calibration and Validation  130  4.080  3.330  3.502  4.658

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 19 outcome measures, including the primary average self-reported pain score and secondary outcomes covering pain scores after block placement, time-based outcomes, sensory blockade, block failures, and maternal and fetal side effects. Evaluating several outcomes can raise a multiplicity concern: general statistical context, when many hypotheses are tested, the chance of at least one apparently unusual result can increase if no adjustment or prioritization is used. Whether and how that issue was addressed in this study is not reported in the registry record.

The registry identifies the primary outcome, but does not describe a prespecified hierarchy for secondary outcomes, multiplicity adjustment, or which outcomes were included in formal testing. No analysis results are listed. It is therefore not possible to distinguish confirmatory findings from exploratory analyses or to assess the impact of multiple testing in the posted record.

The record lists an enrollment of 130 but does not report the analysis population for the primary or secondary outcomes. It does not state how many participants had usable measurements, whether every enrolled participant was followed through the stated timeframe, or how incomplete, missing, or unusable measurements were handled. Missing-data methods and reasons for missingness are not reported in the registry record.

For a measurement study, missingness may affect which pain levels and measurement times are represented. General statistical context: if measurements are more likely to be unavailable under particular circumstances, an analysis limited to observed values can differ from the pattern among all intended observations. The registry record does not provide information to assess whether that issue arose or how it was addressed. The analysis populations and missing-data procedures are not reported in the registry record.

12. 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 the Device Calibration and Validation group with 130 at risk for serious adverse events and 0 serious adverse events. It also lists 130 at risk for other adverse events and 0 other adverse events, with 0 deaths. These are the posted registry counts. The record does not provide event terms in its serious-adverse-event listing.

The at-risk figures describe the denominators recorded for the adverse-event categories; they do not establish that every enrolled participant completed identical follow-up or had the same opportunity for an event to be observed. The record does not describe safety-monitoring procedures, event definitions, duration of ascertainment, or completeness of reporting. Those details are not reported in the registry record.

The counts should not be added across categories. Serious and other adverse-event fields are separate registry categories, and the record does not explain their relationship or provide participant-level detail. The zero counts are not a statistical estimate of risk and do not establish that an event could not occur. They also do not address the performance of the pain-measurement device or the primary endpoint. The posted safety information is limited to the recorded counts and denominators.

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

The registry record describes a completed single-group study that aimed to evaluate an objective pain-measurement device during labor. It identifies patient self-reported pain on a 0 to 10 scale as the primary outcome and describes intended relationships between device readings, verbal pain ratings, analgesia requirements, and concurrent brain oxygenation and hemodynamic measurements.

Those aims are not the same as reported findings. The registry record does not report the observed primary pain-score mean or standard deviation, numerical device measurements, or results for correlations, agreement, or calibration. It also does not report the numerical results for the listed secondary outcomes. Therefore, the posted record does not establish whether the device's readings tracked patient-reported pain, how closely the measurements agreed, or how precisely any relationship was estimated.

The single-group design and absence of a listed comparator mean that the study is not presented as a randomized comparison of alternative treatments. Any patterns observed within the group would not, on their own, establish a causal effect of the device or a treatment effect. The registry summary describes measurement and monitoring aims rather than a treatment-effect question.

The safety listing records zero serious adverse events, zero other adverse events, and zero deaths, with 130 at risk in each adverse-event category. Those counts are limited to what is entered in the registry and do not provide detailed information about ascertainment or follow-up.

In statistical terms, the record supplies the design and outcome definitions but not the results needed to evaluate performance or uncertainty. A completed status indicates the study is marked completed in the registry; it does not substitute for posted outcome estimates. The study's observed results and analysis details are not reported in the registry record. No conclusion about device effectiveness or clinical use follows from the endpoint definitions or the absence of reported numerical results.

14. Why This Trial Matters Statistically

This study raises a central statistical issue in clinical measurement: an objective sensor is useful only if its readings are interpreted in relation to an appropriate reference and their uncertainty is understood. The registry's stated plan to relate a device-based pain measure to patients' verbal ratings addresses a relevant measurement question. At the same time, a stated aim is not evidence of successful validation. Results for the relationship between those measures are not reported in the registry record.

The study also involves measurements that may vary during labor and after epidural. General statistical context: when a quantity changes over time, the timing and structure of observations can affect the summary and its uncertainty. Repeated measurements from the same person may carry related information, so analysis methods should reflect the data structure. The registry does not report the measurement schedule or analysis approach, making it impossible to assess how those considerations were handled.

Its single-group design is important to interpretation. It can be suited to describing measurements and evaluating patterns within the enrolled group, but it does not create a randomized control comparison. The registry's stated questions concern device measurement and associations, not a randomized treatment contrast. The design should therefore be interpreted in terms of measurement evaluation rather than comparative efficacy.

Finally, reporting is part of statistical interpretation. Outcome definitions and enrollment information identify what was planned and who was intended for study, but readers also need estimates, uncertainty, analysis populations, and methods to judge the strength of evidence. Those results and methods are not reported in the registry record. The record therefore makes the measurement objective visible while leaving its empirical performance unresolved.

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 main limitation for interpretation is that the registry record does not report numerical results for the primary outcome or the secondary outcomes. Without the observed mean and standard deviation for self-reported pain, readers cannot characterize the reported score distribution. Without results for the device measure or its relationship to patient reports, the stated measurement objective cannot be evaluated statistically from this record.

Important design and analysis details are also absent. Although the timeframe is given as during labor up to 2 hours after epidural, the record does not describe the timing or frequency of measurement, how repeated readings were handled, how an average was formed, or which participants contributed to each analysis. It does not report the statistical models, uncertainty estimates, analysis populations, or handling of missing values. These details are not reported in the registry record.

The record lists a single group, allocation NA, and no masking, and it does not identify a control group. This limits interpretation to the stated within-group measurement objectives rather than a randomized comparison. The registry's general planning assumptions refer to two-arm illustrations, but those assumptions do not describe the registered single-group design.

The record lists 19 outcome measures but does not report how multiplicity was addressed or whether secondary outcomes were exploratory. Its safety counts have no accompanying description of event definitions, follow-up, or ascertainment. These gaps limit how fully the posted information can be interpreted; they should not be filled by assumptions about the protocol or analysis.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of Objective Pain Measurement Device — NCT03975660.
• Registry record last updated 2025-06-08; status last verified 2025-06.
• Results first posted 2025-06-08.
• 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.

19. Record Summary

NCT03975660 is a completed single-group study titled “Evaluation of Objective Pain Measurement Device,” sponsored by Stanford University. The registry lists an enrollment of 130, a start date of 2019-11-01, and a primary completion date of 2023-10-31. Allocation is listed as NA and masking as none.

The study concerns pain measurement during labor among patients requesting epidural labor analgesia. The primary outcome is average self-reported pain on a 0 to 10 scale during labor up to 2 hours after epidural. The summary describes intended comparison of device readings with verbal pain ratings and analgesia requirements, alongside brain oxygenation and hemodynamic monitoring.

The registry lists 19 outcome measures and no analyses. It records zero serious adverse events, zero other adverse events, and zero deaths, with 130 listed at risk in each adverse-event category. Numerical outcome results, analysis methods, and missing-data procedures are not reported in the registry record.