Memory & Conditioning Under Anesthesia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Memory & Conditioning Under Anesthesia (NCT04062123), a randomized phase 1 study. The primary outcome is Explicit Memory Performance.

2. Clinical Question

3. Trial Design

The registry describes a randomized, single-masked, parallel Phase 1 study, with status recorded as completed. Enrollment is listed as 92. The study start is recorded as 2020-07-30 and primary completion as 2024-04-22. The brief summary says the study occurs over 5 visits and involves no long-term follow up. These registry entries describe the planned and recorded study structure, but do not establish which people were masked or how randomization was carried out.

Four groups have posted primary-outcome results: placebo control, propofol, dexmedetomidine, and fentanyl. Their recorded participant counts are 92, 30, 29, and 33, respectively. The registry record does not explain how the placebo count relates to enrollment or to the other arm counts. Those figures should therefore be read as recorded arm-level information, not reconciled into an assumed allocation or total.

The study’s broad focus is pain’s relationship to long-term memory and conditioned physiologic responses with and without distinct intravenous anesthetics. The record also lists peripheral nerve stimulation, and describes functional magnetic resonance imaging as a way to identify neural correlates. Three secondary outcomes are listed: hippocampal activation for successful memory formation, heart rate response, and skin response. The registry does not provide detailed procedures, timing for those secondary measures, masking details, or a full account of how each intervention was administered.

Randomization can support comparisons between assigned groups when allocation and follow-up are appropriately implemented, but the registry record alone does not establish those implementation details. The posted results are arm-level means with confidence intervals; a formal adjusted or pairwise analysis is not posted.

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 Explicit Memory Performance, measured over 24-hrs post-experiment.

The primary endpoint is explicit memory performance, recorded as a mean in units on a scale. It is assessed 24-hrs post-experiment using recognition testing and the Remember-Know procedure. Participants indicate whether previously experienced experimental items are recognized among novel items that were not part of the experiment.

The registry describes the endpoint as a signal-detection statistic, d'. It combines information about correctly identifying previously experienced items and false positive responses to novel items. The record states that d' is calculated by subtracting the cumulative Gaussian distribution of false positive responses from the cumulative Gaussian distribution of correctly identified previously experienced items. Positive values represent performance above chance, while negative values represent performance worse than chance guessing. The scale is theoretically infinite and expressed in standard deviation units.

A recognition-based endpoint is useful because it summarizes discrimination between previously encountered and novel items rather than simply counting affirmative recognition responses. The Remember-Know procedure is described as allowing calculation of interdependent measures of recollection and familiarity through d'. The registry does not post separate primary results for those components. The reported mean therefore represents the specified combined signal-detection measure, not a direct measure of every memory process or of long-term memory beyond the stated assessment time.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the mean describe?

The primary outcome is a continuous measure, and the registry specifies that the displayed summary is a mean. A mean describes the arithmetic center of the recorded values within a group. It is useful for comparing the location of continuous outcome distributions, but it does not show the spread or shape of individual observations. Two groups can have different means while still having substantial overlap among individual values.

The endpoint is d', a signal-detection measure derived from recognition responses. According to the registry description, it contrasts the cumulative Gaussian distribution for correct identifications with that for false positive responses. In general, signal-detection measures aim to represent discrimination while accounting for both hits and false alarms. The registry supplies the endpoint definition but does not report the participant-level response distributions, the calculation implementation, or separate recollection and familiarity estimates.

How should the confidence intervals be read?

Each posted arm mean is accompanied by a 95% confidence interval. In general, a confidence interval reflects sampling uncertainty under a statistical procedure and its assumptions. It is not a range that contains every participant’s value, nor does it directly describe the variation among participants. The record does not state the interval calculation method, whether any model was used, or whether the intervals account for design features beyond the arm-level data.

A confidence interval around a group mean is not the same as a confidence interval around a difference between groups. To assess a contrast, an analysis would ordinarily estimate the contrast and its uncertainty directly. The registry record does not post those contrast estimates or associated tests. Comparing the separate intervals visually is not a substitute for a formal comparison, because inference about a difference depends on the uncertainty of that difference and the relationship between estimates.

What can randomization contribute?

In general, random allocation can help balance measured and unmeasured baseline characteristics across groups on average, supporting interpretation of between-group contrasts. That benefit depends on implementation, adherence, outcome ascertainment, and the handling of missing observations. The registry labels the study randomized but does not report the sequence-generation method, allocation concealment, deviations from assignment, or an analysis based on assigned groups. Therefore, the design label alone does not establish how those issues were handled.

The study is also described as single-masked, but the identity of the masked party and the procedures used to maintain masking are not reported in the registry record. This information can matter for outcomes influenced by participant expectations, study staff behavior, or outcome assessment. The primary endpoint is a memory test, but the record does not state whether testing or scoring was masked.

What do planning calculations mean?

The registry’s planning assumptions describe calculations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is expressed as a stated fraction of the observed effect. In general, such calculations illustrate the number of participants per arm that might be needed under those assumptions to detect a selected effect with a chosen power. They are planning illustrations, not observed outcomes and not observed power.

The registry record does not report that these assumptions were used to design the trial, and it does not report the trial’s own sample-size justification. No calculated planning values are stated in the registry information discussed for these results. Any planning estimate should be interpreted in light of the assumptions used, especially the choice of effect to detect and the equal-allocation and normal-approximation assumptions. It should not be read as evidence that the completed study achieved a particular power.

Why can over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a statistical model expects. When a model underestimates variability, standard errors may be too small and confidence intervals or tests may be too optimistic. This is a general consideration for statistical modeling, not a reported feature of this trial. The posted primary endpoint uses continuous arm-level means, and the registry record does not describe a model or report an assessment of over-dispersion.

The endpoint is described as theoretically unbounded, but the record does not provide the distribution of observed values or diagnostics. It is therefore not possible to determine from the registry summaries whether a normal approximation was appropriate for the outcome analysis. Such an assessment would require details beyond the arm means and confidence intervals.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three secondary outcomes in addition to the primary endpoint: hippocampal activation for successful memory formation, heart rate response, and skin response. It records four outcome measures and does not post outcome analyses. The registry record does not report a multiplicity strategy, such as a testing hierarchy or adjustment for multiple comparisons. Without such information and without the analyses, the statistical significance of any secondary result cannot be assessed from the record.

Missing-data methods are not reported in the registry record. The record does not state whether all participants contributed primary endpoint data, how missing memory tests were handled, or whether any sensitivity analyses were conducted. The posted arm counts and means do not establish the amount or pattern of missing outcome data. General statistical interpretation depends on these details because missingness can affect both the estimate and its uncertainty.

Analysis populations are also not reported in the registry record. It is not stated whether analyses followed randomized assignment, included only participants who completed assigned procedures, or used another population definition. The registry labels the study randomized, but that does not identify which population underlies the posted means.

No sponsor analysis or adjusted treatment contrast is posted. The record also does not report interim analyses, a prespecified statistical analysis plan, or a sample-size justification. These omissions limit assessment of whether the reported endpoint, analysis population, and treatment contrasts were chosen before outcome data were examined. They do not establish that such procedures were absent; they mean that they are not reported in the registry record.

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’s adverse-event figures list zero serious adverse events for propofol, dexmedetomidine, and fentanyl. Deaths are recorded as zero in each of those groups. The counts for other adverse events are recorded as zero for propofol, zero for dexmedetomidine, and 2 for fentanyl. These are the posted counts, not estimates of comparative risk.

The registry lists 30 participants at risk for serious and other adverse events in the propofol group, 29 in the dexmedetomidine group, and 33 in the fentanyl group. It does not post adverse-event groups for placebo control in this record. A count of zero means no event was recorded in the relevant group under the registry’s reporting; it does not demonstrate that an event could not occur. The record does not define the adverse-event collection window, describe event ascertainment, or provide details about the two other adverse events recorded for fentanyl.

With no posted comparative analysis, these figures should not be interpreted as evidence that the groups have the same or different safety profiles. They are descriptive registry counts, and the record does not provide information to assess the precision of comparisons or the clinical nature of the events.

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

The results describe average performance on a specific recognition-memory measure at 24-hrs post-experiment. They do not provide a direct estimate of a drug-versus-placebo difference. The posted means are 1.16 for placebo control, 0.51 for propofol, 1.04 for dexmedetomidine, and 0.98 for fentanyl, each with its own 95% confidence interval. Because the registry does not post contrast estimates or tests, these values should be treated as descriptive arm summaries rather than definitive comparisons.

The endpoint is one aspect of the study’s broader subject: memory and conditioned physiological responses in relation to pain and anesthetics. It is not a complete account of long-term memory, conditioning, brain activity, or pain. The record lists hippocampal activation, heart rate response, and skin response as secondary outcomes, but does not post analyses for them. The functional magnetic resonance imaging objective is described in the study summary; the registry does not provide the corresponding results in the information recorded.

The means are positive on the d' scale, which the registry describes as representing performance above chance guessing. That interpretation concerns the scale’s meaning; it is not a reported statistical test against chance. Nor does a positive mean establish that every participant performed above chance. The record provides group means and intervals, not individual results.

The trial is labeled randomized and completed, but essential details for evaluating its estimates are not reported, including analysis populations, missing-data handling, and the statistical analysis plan. The reported arm counts also require caution because the registry does not explain the relationship between the placebo count and the enrollment count. These limits prevent the posted summaries from answering every causal or comparative question raised by the study’s broad aims.

The results therefore document the registered arm-level outcome values and their reported uncertainty. They do not, by themselves, establish a treatment effect, a safety difference, or a broader conclusion about memory or conditioning beyond the specified endpoint and assessment time.

13. Why This Trial Matters Statistically

This trial illustrates why a registry’s outcome values need to be distinguished from treatment-effect estimates. A mean within each group describes that group, while a comparative question requires an estimate of the difference between groups and its uncertainty. The registry posts arm means and confidence intervals for explicit memory performance, but no analysis of the comparisons. Readers can describe the recorded values, yet cannot use them as a substitute for an unreported contrast.

The endpoint also highlights the importance of understanding measurement. The primary outcome is not a simple count of correct answers; it is d', derived from recognition of studied items and false positive responses to novel items. Its stated interpretation gives useful context to the scale, but the combined statistic does not reveal the separate contribution of recollection and familiarity in the posted results.

The study’s objectives span memory, conditioned physiological responses, pain, anesthetics, and neural correlates. The registry lists secondary outcomes relevant to some of those domains, but does not post analyses. This makes the distinction between a broad research question and the particular outcome with published registry values especially important. A single endpoint cannot stand in for every part of the study’s stated purpose.

The record also demonstrates how design labels and reporting details work together. Randomization and masking are recorded, but the methods that would clarify their implementation, along with missing-data handling and analysis populations, are not reported. Arm-level counts do not resolve those gaps, particularly when the registry does not explain the relationship between the placebo count and enrollment. Careful interpretation depends not only on the numerical estimate, but also on knowing which observations and procedures produced it.

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 registry record leaves several trial-specific questions unresolved. It does not report eligibility criteria, baseline characteristics, randomization procedures, allocation concealment, or the identity of the party masked in this single-masked study. These omissions make it difficult to assess the enrolled population and the practical implementation of the design from registry information alone.

The primary results are arm means and confidence intervals, without posted treatment contrasts, p-values, or analysis details. The method used to calculate the confidence intervals is not reported in the registry record. Analysis populations, missing-data handling, outcome distributions, and the handling of protocol deviations are also not reported. As a result, the precision and comparability of the posted summaries cannot be fully evaluated.

The arm counts merit particular caution: enrollment is listed as 92, and the placebo control arm is also recorded as 92, while the active-drug arms have their own posted counts. The registry record does not explain this relationship. No reconciliation should be assumed from the entries alone.

The registry states that the study involves 5 visits and no long-term follow up, while the primary endpoint is assessed 24-hrs post-experiment. This limits what the posted endpoint can say about memory beyond that assessment. The record does not provide details of the memory-test administration or the role of peripheral nerve stimulation in the arm structure. Nor does it post the analyses for the listed secondary outcomes. These limitations restrict interpretation to the reported primary arm summaries and the descriptive adverse-event counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Memory & Conditioning Under Anesthesia — NCT04062123.
• Registry record last updated 2025-04-18; status last verified 2025-03.
• Results first posted 2025-04-18.
• 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

The registry record describes NCT04062123, titled Memory & Conditioning Under Anesthesia, as a completed, randomized, single-masked, parallel Phase 1 study. Enrollment is recorded as 92. The study examined pain, memory, and conditioned physiological responses in relation to anesthetics, with functional magnetic resonance imaging described as part of the research aims.

The primary endpoint is mean explicit memory performance using d' at 24-hrs post-experiment. Posted means and 95% confidence intervals are available for placebo control, propofol, dexmedetomidine, and fentanyl. No outcome analyses or treatment contrasts are posted in the registry record. Three secondary outcomes are listed, but their analyses are not posted. Adverse-event figures record no serious events or deaths in the three drug groups, and 2 other adverse events in the fentanyl group.

The registry does not report the analysis plan, analysis populations, missing-data methods, or the explanation for the recorded arm-count relationship. These omissions limit interpretation of the arm-level summaries.