The Realtime Detection for Individual Variation of Analgesic ：A Comparison of Sufentanil vs Fentanyl: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Realtime Detection for Individual Variation of Analgesic ：A Comparison of Sufentanil vs Fentanyl (NCT01748071), a registered phase not stated study. The primary outcome is Mean Pressure Pain Threshold.

2. Clinical Question

The stated purpose emphasizes individual sensitivity differences as well as analgesic effect. The listed endpoint is a continuous measure summarized as a mean with standard deviation, but the registry does not describe how individual sensitivity was operationalized or analyzed. It also does not state whether the primary comparison was between all groups, between selected pairs, or based on another contrast. Because allocation is not stated, group differences could not automatically be attributed to the injected substance. The registry record does not report the statistical analysis needed to answer the clinical question.

3. Trial Design

This record describes a completed study of three groups in the setting of elective surgery under general anesthesia. The listed groups are the Sufentanil Group, the Fentanyl Group and the Saline Group. The descriptions state that sufentanil or fentanyl was given intravenously at anesthesia induction, while saline was given before anesthesia induction. The timing and procedures are therefore not described in identical terms for all groups.

The brief summary says 120 female patients receiving elective surgery under general anesthesia were recruited. Enrollment is recorded as 120. The safety data list 38 at risk in the Sufentanil Group, 38 in the Fentanyl Group and 40 in the Saline Group. These are the group-specific denominators recorded for those safety figures; the registry does not explain how they relate to the enrollment figure or provide a participant flow account.

The record identifies the study as completed. Its recorded start is 2012-06 and primary completion is 2012-12. It names Huazhong University of Science and Technology as sponsor. The conditions are listed as Surgery and Individuality. The registry does not report a randomization method, concealment method, blinding, or a protocol explaining allocation. It explicitly notes that allocation was not stated and that the arms are not a like-for-like control comparison. The design should therefore be read as a multi-group comparison with unclear allocation, rather than assumed to be a randomized controlled trial.

The record lists five outcome measures and identifies Mean Arterial Pressure, Mean Heart Rate and Mean Respiratory Frequency as secondary outcomes. It does not list all five outcome titles in the information available for this account. No analysis is recorded. These omissions limit interpretation: the listed groups and planned measurements describe the study question, but they do not establish that outcome data were collected for every participant or that a particular comparison was performed.

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:

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 Pressure Pain Threshold, measured over 10 minutes after the procedure.

The primary endpoint is Mean Pressure Pain Threshold. It is recorded as a continuous measure, expressed in kg/cm2 and summarized using a mean and standard deviation. The specified timeframe is 10 minutes after the procedure. The description says the measure was taken according to pressure-pain-threshold measurement after intravenous opioid analgesics.

In general, a pressure pain threshold is a measurement of the pressure at which a person reports pain under a defined assessment procedure. It can serve as a quantitative way to compare responses to a pressure stimulus. Its interpretation depends on how the stimulus is applied, how the threshold is elicited and recorded, and whether the measurement procedure is consistent across groups. The registry record does not describe those operational details, nor does it explain the clinical meaning of a particular threshold value.

Using a mean and standard deviation describes the center and spread of a continuous outcome. The mean indicates the average recorded value within a group; the standard deviation describes variation among recorded values around that mean. Neither statistic is available for this endpoint in the registry record. The record also does not report group sizes for the primary endpoint, an estimated contrast, a confidence interval, or a significance test. As a result, the endpoint definition can be described, but its observed level and comparative result cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry is sparse. It identifies the primary outcome as a continuous measure summarized by a mean and standard deviation, but records no analyses and does not provide outcome values. The following concepts explain how such information would ordinarily be interpreted; they do not describe analyses documented for this study.

What does a mean and standard deviation describe?

In general, a mean is the arithmetic average of recorded observations in a group. It provides a measure of the group’s central value, but it does not show how widely individual observations vary. The standard deviation describes the spread of observations around the mean. A mean and standard deviation together can help readers understand both the typical recorded level and its variability, provided the measurement and analysis are appropriate.

These summaries do not show the full shape of a distribution. A mean can be influenced by unusually high or low observations, and a standard deviation does not reveal whether the distribution is symmetric or has outliers. A statistical comparison may need to account for distributional features and the way participants were assigned or observed. The registry does not report distribution checks, methods for handling unusual values, or an analysis plan.

What would a group contrast tell the reader?

In general, a contrast compares outcomes between groups using a defined scale and direction. For a continuous endpoint, a contrast could be expressed as a difference in group means, but the intended comparison must be specified. A study with three groups can pose several possible pairwise or overall questions. The registry record does not state which contrast was designated as primary, whether all groups were compared together, or how the saline group was intended to contribute to the analysis.

A contrast is not established merely because groups are listed. The analysis also needs outcome data, an appropriate comparison method, and a clear account of the population included. None of those results or analytic details is reported for the primary endpoint. Consequently, no estimated group difference can be described from the registry record.

Why do confidence intervals matter?

In general, a confidence interval gives a range of values compatible with the observed data and the statistical model at a stated confidence level. It communicates uncertainty around an estimate, rather than only whether a test crosses a decision threshold. A narrow interval indicates greater precision under the model; a wide interval indicates less precision. The interval does not remove design limitations, measurement error, or bias, and it is not a guarantee that the true value lies within its bounds.

No confidence interval is reported for the primary outcome. There is therefore no basis for describing the precision of a group difference. The registry also reports no p-value or test statistic. A p-value, in general, measures how unusual data at least as extreme as those observed would be under a specified null model and its assumptions. It is not the probability that a treatment works, and it does not measure the size or practical importance of an effect.

How should the allocation information affect interpretation?

In general, random allocation can help balance both measured and unmeasured participant characteristics across groups, while nonrandom allocation may leave differences that complicate causal interpretation. The registry does not say that allocation was randomized; it says allocation was not stated and flags the arms as not a like-for-like control comparison. The description of the saline timing also differs from the timing listed for the opioid groups. These details make it especially important not to interpret any hypothetical group contrast as an isolated drug effect.

Adjustment for baseline variables can sometimes address measured imbalances, but it cannot necessarily remove unmeasured confounding. The registry does not report baseline characteristics, an adjusted model, or the variables that might have been included in one. No adjusted or unadjusted treatment estimate is posted. It would be inappropriate to assume that adjustment was performed or that any particular model was used.

What does the planning illustration represent?

The described sample-size illustrations use the observed effect as their planning basis, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The intended effect is expressed as a stated fraction of the observed effect. These are planning illustrations, not the study’s own design justification. The registry does not report a sample-size justification for the trial, and the illustrations do not establish the study’s actual power.

In general, planning calculations estimate the number of participants that a future study might require under specified assumptions about an effect, variability, allocation and testing procedure. Their result depends on those assumptions. An illustration based on an effect observed in the same study is uncertain because the observed effect may not represent the effect a future study would see. It should not be described as observed power or as proof that the completed study was adequately sized. The registry does not give a protocol-based target, an assumed effect for its original design, or a rationale for enrollment.

The stated calculation approach applies to two-arm comparisons and therefore does not, by itself, describe how the three listed groups would be analyzed together. The registry does not state whether the planning comparisons correspond to the primary question, which pairs were considered, or whether multiplicity was taken into account. Any numerical planning values should be read as hypothetical design aids tied to their assumptions, not as trial outcomes.

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("Sufentanil Group", "Fentanyl Group", "Saline Group")
n   <- c(38, 38, 40)
m   <- c(9.93, 6.2, 2.36)
sp  <- c(3.5, 3, 0.97)
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  Sufentanil Group  38  9.930  3.500  8.780  11.080
CARM  Fentanyl Group  38  6.200  3.000  5.214  7.186
CARM  Saline Group  40  2.360  0.970  2.050  2.670

11. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures, identifies Mean Pressure Pain Threshold as the primary endpoint, and names Mean Arterial Pressure, Mean Heart Rate and Mean Respiratory Frequency as secondary outcomes. It does not list all five outcome titles in the information available for this account. Although one endpoint is designated primary, the registry does not report a statistical analysis or results for any endpoint.

Multiplicity arises in general when several outcomes, time points or group contrasts are tested. Repeated testing can increase the chance of obtaining at least one apparently noteworthy result by chance. Researchers may specify a testing hierarchy, adjust significance thresholds, or identify a limited primary comparison in advance. The registry does not report a multiplicity strategy, a hierarchy among outcomes, or which group contrasts were planned. No adjustment method should be inferred.

The record also does not describe missing data. It does not report the number of participants with primary endpoint measurements, reasons for missing measurements, or methods used to handle missing values. The safety denominators are reported by group, but they do not establish how many primary outcome observations were available. The record does not state whether analyses followed an intention-to-treat, per-protocol, or other population definition.

These omissions matter because analysis populations and missing-data methods can affect estimates and their uncertainty. In general, a complete-case analysis, an imputation method and a model using available repeated observations rely on different assumptions. Without a participant flow description, outcome-specific denominators, or a stated analysis population, readers cannot evaluate whether missingness could have influenced results. Since no outcome analysis is reported, the registry provides no estimate whose robustness to these issues can be assessed.

12. Safety Results

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

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 zero serious adverse events and zero other adverse events for the Sufentanil Group, with 38 at risk. It lists zero serious adverse events and zero other adverse events for the Fentanyl Group, with 38 at risk. For the Saline Group, it lists zero serious adverse events and zero other adverse events, with 40 at risk. No serious adverse-event terms are listed.

These entries should be read as the adverse-event figures recorded in the registry, not as proof that no events occurred under any definition or observation period. The record does not describe the event-collection method, event definitions, follow-up duration, or completeness of reporting. The deaths field is not reported as a number for these groups; it should not be interpreted as a zero count.

In general, adverse-event counts require context about how events were sought, classified and monitored. The figures do not provide an adjusted comparison of safety between groups, and no such analysis is reported in the registry record. The listed at-risk counts are specific to the safety entries and should not be assumed to be the denominators for the primary endpoint.

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

The record establishes that a completed study compared groups described as receiving sufentanil, fentanyl or saline around anesthesia induction in female patients undergoing elective surgery under general anesthesia. It identifies Mean Pressure Pain Threshold as the primary endpoint and specifies measurement 10 minutes after the procedure. It also describes intended observations involving analgesia, the Narco-trend index, sedation, respiration and cardiovascular effects.

What it does not establish is the observed pressure-pain-threshold value in any group, the size or direction of a comparison, the uncertainty around a comparison, or whether a statistical test found evidence of a difference. The registry records no analyses. It also does not report results for the listed secondary outcomes or quantify individual variation. The study’s completed status is not a substitute for outcome reporting.

The record further does not establish that group differences, if reported elsewhere, would be attributable to the assigned substance. Allocation is not stated, and the record explicitly cautions that the arms are not a like-for-like control comparison. It does not describe blinding, baseline comparability, adjustment, or the intended primary contrast. Without those details, causal interpretation would be limited even if numerical group summaries were available.

In general, a result can be statistically distinguishable from a null value without being clinically important, while an uncertain estimate can remain compatible with a range of effects. That distinction cannot be evaluated in this case because the estimate and its precision are not reported. No conclusion about efficacy, lack of efficacy, or comparative safety follows from the registry entries alone.

The appropriate conclusion is narrow: the registry documents a study question and endpoint, but not the results needed to answer that question. Readers should treat the posted adverse-event zeros as recorded counts with limited reporting context, and should not infer that unreported outcomes or deaths were zero.

14. Why This Trial Matters Statistically

This study is statistically notable because its stated aim includes individual variation, while the primary endpoint is reported as a group-level mean and standard deviation. A mean can describe the center of a group’s measurements, but it does not by itself characterize how treatment responses vary from person to person. Studying individual variation requires an explicit definition and analysis, such as a model or summary that distinguishes within-group variability from between-group differences. The registry does not report such a definition or analysis.

The record also illustrates why a named primary endpoint is not enough to support interpretation. The endpoint, unit and timeframe are specified, but its results are absent. Without an estimate and a measure of uncertainty, readers cannot assess the magnitude or precision of a group contrast. The designation of an endpoint as primary helps identify the intended focus; it does not substitute for outcome reporting.

Another statistical issue is comparability. The three groups have different descriptions of timing, and the registry does not state how allocation occurred. It explicitly warns that the arms are not a like-for-like control comparison. This makes design information essential: a numerical contrast alone would not establish that the intervention caused an observed difference.

Finally, the record contains a sample-size planning description but no reported analysis. Planning illustrations based on an observed effect are not evidence of achieved power, and they do not explain the original enrollment decision. The absence of an analysis plan, missing-data account and multiplicity strategy further limits what can be learned from the registry entry. These features make the study a useful example of the difference between registering a measurement and reporting evidence about it.

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 is that the registry does not report the primary outcome values or any statistical analyses. Mean Pressure Pain Threshold is defined, but its group means, standard deviations and comparative estimates are not reported. The record also gives no confidence interval or p-value. This prevents assessment of effect direction, magnitude and precision.

The record does not state how allocation was carried out. It specifically notes that allocation was not stated and that the arms are not a like-for-like control comparison. It does not report blinding or baseline characteristics. The descriptions also differ in the timing of saline relative to anesthesia induction. These issues limit interpretation of any group differences as effects of the injected substances.

The registry does not explain the participant flow or reconcile the enrollment entry with the group-specific at-risk counts used for adverse-event reporting. It does not give primary-outcome denominators, missing-data reasons, or an analysis population. The record does not describe the pressure-pain-threshold measurement procedure in enough detail to assess reproducibility, nor does it report how individual sensitivity was defined or evaluated.

The record lists five outcome measures but does not report all outcome titles in the information, and it does not state how multiple outcomes or group contrasts were handled. It also does not provide an original sample-size justification. The adverse-event entries lack a stated observation period and collection method, and deaths are not reported numerically. These limitations do not show that the study was conducted improperly; they describe what cannot be evaluated from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Realtime Detection for Individual Variation of Analgesic ：A Comparison of Sufentanil vs Fentanyl — NCT01748071.
• Registry record last updated 2013-11-25; status last verified 2013-09.
• Results first posted 2013-11-25.
• 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

NCT01748071 is recorded as a completed study sponsored by Huazhong University of Science and Technology. Its recorded start is 2012-06 and primary completion is 2012-12. The registry describes 120 female patients undergoing elective surgery under general anesthesia and lists sufentanil, fentanyl and saline groups.

The primary endpoint is Mean Pressure Pain Threshold, a continuous measure summarized by mean and standard deviation, with assessment 10 minutes after the procedure and units of kg/cm2. The record lists five outcome measures and identifies Mean Arterial Pressure, Mean Heart Rate and Mean Respiratory Frequency as secondary outcomes. It records zero analyses, and primary and secondary outcome results are not reported in the registry record.

Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. The adverse-event entries list zero serious and zero other events in each group, while deaths are not reported as numerical values. The registry’s study question is documented, but the posted information does not provide the outcome estimates needed to assess the comparative results.