Comparison of Total Oxidant and Total Antioxidant Capacities in Low-Flow and High-Flow General Anesthesia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Total Oxidant and Total Antioxidant Capacities in Low-Flow and High-Flow General Anesthesia (NCT05590312), a registered phase not stated study. The primary outcome is Comparison of Total Antioxidant Status (TAS) Levels Between the Two Groups.

2. Clinical Question

The registry frames the study as an investigation of whether low-flow anesthesia contributes positively to total oxidant/antioxidant balance. Its named primary outcome is the comparison of TAS between groups, while the descriptions also mention total oxidant status (TOS), Vitamin D, Albumin and CRP. The clinical question is therefore about measured laboratory values under two anesthesia-flow protocols, not a reported comparison of clinical recovery or other patient outcomes.

The study is identified as observational, and allocation to the flow groups is not stated. The registry record cautions that the arms are not a like-for-like control comparison. Consequently, even if a difference in TAS were reported, the record would not by itself establish that flow rate caused that difference. The record gives no participant characteristics or adjustment details with which to assess the comparability of the groups.

3. Trial Design

This is a completed observational study sponsored by Duzce University. The registry lists an enrollment of 72 and describes two groups of 36 patients each: Low Flow Group - Group D and High Flow Group - Group Y. Both groups received general anesthesia. The low-flow protocol is described as 1 L/min and the high-flow protocol as 4 L/min during the operation.

The registry gives the study start as 2022-08-01 and the primary completion as 2023-11-01. Its status is COMPLETED. The intervention entry is general anesthesia, classified as OTHER; the differing flow protocols are described in the group descriptions. Allocation is not stated, and the record explicitly cautions that the groups are not a like-for-like control comparison. Further details on how patients entered each group are not reported in the registry record.

The group descriptions state that processed EEG values were monitored and that patients would be ensured to be at the same “an” before the text cuts off. The intended condition is therefore incomplete in the registry description and should not be reconstructed. Other details that would help interpret the design, including the inclusion and exclusion criteria, baseline characteristics, and whether any matching or adjustment was used, are not reported in the registry record.

The primary outcome is a comparison of mean TAS levels between groups. The stated measurement schedule is before the operation, at the end of the operation, and at the 6th hour after the end of the operation; the registry describes these as three measurements within 24 hours perioperatively. Values are specified in mmol Eq / L. The record also describes repeat postoperative measurements of Albumin, CRP, TAS and TOS and comparisons with earlier values within the same group. It lists five outcome measures, but their full details beyond the named primary outcome are not reported in the registry record.

Although the study status is completed, no analysis entries are listed. Numerical outcome results, participant flow, and details of the analysis population 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 Comparison of Total Antioxidant Status (TAS) Levels Between the Two Groups, measured over 3 times in 24 hours perioperatively. TAS/TOS levels will be determined before the operation, at the end of operation and at 6th hour after the end of operation..

The primary endpoint is the comparison of total antioxidant status (TAS) levels between the two groups. TAS is a continuous laboratory measure reported in mmol Eq / L. The registry specifies that results are to be described as a mean with standard deviation. It plans measurements before the operation, at the end of the operation, and at the 6th hour after the end of the operation.

As a general statistical point, a continuous endpoint preserves information about the measured value rather than reducing it to a category such as above or below a threshold. Comparing means can describe whether average measured TAS differs between groups at a given time. Standard deviations describe how dispersed individual measurements are around the mean; they are not the same as the uncertainty in the estimated difference between group means.

Repeated measurement is relevant because TAS is planned at more than one perioperative time. Within-group changes and between-group comparisons answer different questions: a within-group comparison concerns change over time among patients in one group, while a between-group comparison concerns the relative values across the two groups. The registry mentions both types of comparison in its endpoint description. It does not report the observed means, standard deviations, changes, between-group differences, confidence intervals, or tests. The endpoint's planned role can therefore be described, but the magnitude and precision of any observed TAS result cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies TAS as a continuous outcome and specifies a mean and standard deviation as its summary format. It also specifies three perioperative measurement times. These details describe the intended data structure, but the record does not report an analysis plan or analysis results. The explanations below are general statistical principles and should not be mistaken for methods confirmed to have been used in this study.

What does a mean comparison describe?

For a continuous measurement, a group mean represents the average observed value in that group. A comparison of group means describes the difference in average values, but the mean alone does not show how much individual measurements vary. The standard deviation gives a measure of that spread. A small standard deviation indicates observations are relatively concentrated around the mean; a larger one indicates more variability. Standard deviation does not, by itself, give the precision of a group comparison. Precision also depends on sample size and on the method used to estimate uncertainty.

The registry states that TAS is summarized as a mean with standard deviation, but it does not post those summaries. It also does not report a mean difference or its confidence interval. Therefore, there is no numerical estimate to interpret. A general explanation of mean comparisons cannot establish what happened in either group.

Why are repeated measurements different from one-time comparisons?

TAS is planned before the operation, at the end of the operation, and at the 6th hour after the end of the operation. Measurements from the same patient are related: a person's later value is not statistically independent of that person's earlier value. General methods for repeated data account for this within-person relationship. Treating all measurements as though they came from different people can misstate uncertainty.

There are several possible statistical questions in a repeated-measure setting. One is whether the groups differ at a particular measurement time. Another is whether values change over time within one group. A further question is whether the pattern of change differs between groups. These questions are not interchangeable. The registry description mentions comparisons between groups and comparisons with previous levels in the same group, but does not state which statistical method was used or how the questions were organized.

What does a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimate, such as a mean difference. It helps readers judge whether the estimate is precise or compatible with a broad range of possible values. A narrow interval indicates greater precision than a wide interval, given the method and assumptions. It does not remove potential bias from group differences, measurement issues, or other design limitations. No confidence interval is reported for TAS in the registry record, so precision cannot be assessed.

How should a p-value be understood?

In general, a p-value is calculated relative to a null hypothesis and a statistical model. It is not the probability that the null hypothesis is true, nor does it express the size or practical importance of a difference. A small p-value can occur for a small difference when data are sufficiently informative, while a larger p-value does not establish that groups are equivalent. The record does not report a p-value or test for the primary outcome. The stated two-sided significance level of 0.05 appears in the assumptions for a planning illustration; it does not establish the threshold or procedure used in an actual analysis.

Why can over-dispersion matter?

As a general concept, over-dispersion occurs when observed variability is greater than a statistical model assumes. It is especially relevant to outcomes modeled as counts or events, where an overly restrictive variance assumption can make standard errors too small and tests too optimistic. TAS is a continuous measurement, and the registry does not describe a count model or report evidence of over-dispersion. It would therefore be inappropriate to assert that over-dispersion occurred in this study. For continuous data, the broader lesson is to examine whether the chosen model represents the data's variability and dependence structure adequately; the registry does not report those diagnostics or modeling choices.

What does the sample-size illustration mean?

The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. They describe an illustration using fractions of an observed effect, not the trial's original design. General sample-size calculations estimate how many participants per arm might be needed for a specified power under assumed effect and variability conditions. These values are planning illustrations rather than observed power. The record does not report the trial's own sample-size justification, the numerical illustration outputs, or the effect and variability values used. The actual enrollment of 72 is a registry fact, not evidence that the study was adequately powered for the primary outcome.

Because there are no analysis results or methods entries, these principles provide context for reading the planned endpoint rather than a reconstruction of the study's statistical work. The method used for the primary comparison, handling of repeated measurements, missing observations, and any adjustment for multiple testing are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures and describes more than one perioperative measurement time for TAS and other laboratory values. When several outcomes, time points, or contrasts are tested, the chance of at least one apparently notable result can increase. As a general statistical principle, an analysis plan may specify which comparison is primary and whether any adjustment or hierarchy will be used. The registry names a primary TAS comparison, but adjustment for multiple testing and the planned treatment of other outcomes are not reported in the registry record.

The record states a schedule of measurements before the operation, at the end of the operation, and at the 6th hour after the end of the operation. It does not report how incomplete measurements were handled, whether all enrolled patients contributed data at each time, or whether any imputation or other missing-data method was used. The number of participants with available data for the primary endpoint is not reported in the registry record.

Analysis populations are also not described. It is not reported whether analyses included all enrolled participants, only participants with available measurements, or another defined group. Allocation is not stated, and no analysis adjustment details are reported. These omissions matter because the participant set and missing-data approach can affect the estimate and its uncertainty. No assumptions about missingness, exclusions, or analysis populations can be made from the registry entry.

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 reports zero serious adverse events and zero deaths in each group. It lists 36 participants at risk for serious events and 36 at risk for other events in the low-flow group, and the same counts in the high-flow group. The number recorded as having other adverse events is also zero in each group. No serious adverse event terms are listed.

These figures are counts recorded in the registry, not proof that no adverse event occurred in any broader sense. Interpretation depends on how events were defined, collected, and reported, as well as on the observation period. Those details are not reported in the registry record. A zero count also does not establish that the groups have equal safety profiles; the figures alone do not quantify uncertainty or exclude events that were not captured or entered.

The adverse-event counts should be read separately from the primary TAS endpoint. They do not provide evidence about the measured antioxidant status, nor do they answer the primary laboratory comparison. The registry does not report comparative safety tests or confidence intervals for these counts. Thus, the posted figures describe the recorded events and denominators, while leaving the precision and completeness of safety ascertainment unreported.

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

The registry record describes an observational comparison of TAS under low-flow and high-flow general anesthesia protocols. It specifies group sizes, flow rates, the laboratory measure, and the planned measurement times. It does not report numeric TAS outcomes or statistical analyses. The record therefore cannot establish the direction, magnitude, or precision of a difference between groups, and it cannot answer whether the primary comparison was statistically distinguishable from no difference.

Even if outcome values were available, the study's observational design and unstated allocation would matter to interpretation. The record cautions that the arms are not a like-for-like control comparison. In general, an observed group difference in an observational study may be associated with differences in participant characteristics or care that are not the exposure of interest. The registry does not provide the information needed to assess those possibilities or to determine whether any adjustment was made. A group comparison alone would not establish that flow rate caused a change in TAS.

The endpoint is a laboratory measure, not a clinical outcome. The registry's stated aim concerns total oxidant/antioxidant balance, but no results for TAS or TOS are reported in the record. The available description does not establish whether any laboratory difference would correspond to a patient-important benefit or harm. No treatment recommendation or clinical conclusion follows from the planned endpoint description.

The recorded adverse-event counts are zero in both groups, but those counts do not establish the absence of risk or prove equal safety. The registry does not report event definitions, completeness of collection, or comparative uncertainty. The central interpretation is therefore bounded: the record documents a completed study and a planned biomarker comparison, but does not provide the results needed to evaluate that comparison.

13. Why This Trial Matters Statistically

This study is statistically notable because it plans repeated measurements of a continuous laboratory outcome in two groups and describes both between-group and within-group comparisons. Those questions require clear separation in analysis and interpretation. A difference between groups at one time is not the same estimand as change within a group, and a difference in change over time is a further question. The registry names the measurement schedule but does not report how these comparisons were analyzed.

The record also illustrates the importance of distinguishing an observational comparison from a randomized comparison. Allocation is not stated, and the registry cautions that the groups are not like-for-like controls. That design context affects whether a contrast can be interpreted causally. Without participant characteristics and analysis details, readers cannot assess group comparability or the role of potential confounding.

Reporting the endpoint definition, units and intended summary format is useful, but statistical interpretation also requires results and uncertainty measures. The absence of group means, standard deviations, estimates, confidence intervals and analysis results prevents assessment of effect size and precision. A completed status does not fill that reporting gap.

The record's planning assumptions also illustrate an important distinction: a retrospective sample-size illustration is not the original design justification and is not observed power. Planning calculations depend on assumptions about effect size and variability; they cannot replace transparent reporting of the actual estimate and its uncertainty. Together, these issues make the registry entry a useful description of a proposed comparison, while limiting what can be concluded statistically from the posted information.

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.

Several trial-specific details needed to interpret the comparison are not reported in the registry record. Allocation to the flow groups is not stated, and the registry explicitly warns that the groups are not a like-for-like control comparison. The participant characteristics, eligibility criteria, recruitment details, and reasons for assigning a particular flow protocol are not reported. The groups' comparability at baseline therefore cannot be assessed from the record.

The group descriptions state that processed EEG values were monitored and that patients would be ensured to be at the same “an,” but the description ends before completing that phrase. Its intended meaning is not reported in the registry record. The exact handling and timing of laboratory sample collection beyond the stated measurement schedule are also not detailed. The record does not provide information about assay procedures or laboratory measurement quality.

Although the registry lists five outcome measures, only the primary TAS comparison is described in detail in the available record. The other outcome definitions, the statistical analysis plan, the methods for repeated data, and any adjustment for multiple comparisons are not reported. Missing-data procedures and analysis populations are also not reported. These omissions prevent assessment of how the planned comparisons were implemented.

Most importantly, no numerical primary outcome results or statistical analyses are listed. The recorded enrollment and group descriptions cannot substitute for observed outcome data. As a result, neither the size nor the uncertainty of the TAS comparison can be evaluated, and no causal or clinical interpretation is supported by the registry entry alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of Total Oxidant and Total Antioxidant Capacities in Low-Flow and High-Flow General Anesthesia — NCT05590312.
• Registry record last updated 2025-01-17; status last verified 2025-01.
• Results first posted 2025-01-17.
• 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

NCT05590312 is a completed observational study sponsored by Duzce University. The registry lists an enrollment of 72 and describes 36 patients in a low-flow group receiving 1 L/min and 36 in a high-flow group receiving 4 L/min during general anesthesia. The study dates are 2022-08-01 and 2023-11-01 for start and primary completion, respectively.

The primary outcome is the comparison of mean TAS levels, measured in mmol Eq / L, before the operation, at the end of the operation, and at the 6th hour after the end of the operation. The registry also mentions Vitamin D, Albumin, CRP and TOS. Allocation is not stated, and the record cautions that the groups are not a like-for-like control comparison.

No outcome analysis entries or numerical TAS results are reported in the registry record. The adverse-event listing records zero serious events, zero other events and zero deaths in each group. The record does not report the analysis plan, missing-data handling, or analysis populations.