Effect of Dexmedetomidine on Postoperative Glucose and Insulin Levels.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Dexmedetomidine on Postoperative Glucose and Insulin Levels. (NCT03809182), a randomized phase 4 study. The primary outcome is Plasmatic Glucose Levels (mg/dl)..

2. Clinical Question

The trial asks whether glucose levels change over the first postoperative hours in obese patients with impaired glucose tolerance who undergo bariatric surgery, and how those measurements compare between patients assigned to dexmedetomidine and those assigned to 0.9% sodium-chloride. The registered primary outcome is plasmatic glucose, measured in mg/dl at baseline and at repeated times after the onset of the bolus and infusion. The registry describes the study population as obese patients undergoing bariatric surgery and identifies bariatric surgery candidacy, glucose intolerance, and insulin resistance among the conditions.

The clinical question is about a measured metabolic outcome in the perioperative setting. It is not, on the information in the registry record, a question about long-term glucose control, later diabetes outcomes, or the effect of dexmedetomidine outside surgery. The registry also lists secondary outcomes relating to fentanyl consumption, morphine consumption, pain scores, sedation-agitation scores, and postoperative nausea and vomiting. Those outcomes are distinct from the primary glucose question.

3. Trial Design

The registry identifies this as a Phase 4, randomized, quadruple-masked, parallel-group trial. Enrollment was 40. The study status is completed. Its recorded start date is 2012-09-27, and its primary completion date is 2013-07-25. The sponsor is Pontificia Universidad Catolica de Chile.

Participants were randomized to dexmedetomidine or 0.9% sodium-chloride. The dexmedetomidine description states that treatment began after anesthesia induction with a bolus of 1ug/kg in 10 minutes, followed by an infusion of 0.5ug/kg/h until the end of surgery. The saline group is described as receiving a bolus and infusion of 0.9% normal saline at the same rate as the dexmedetomidine group. Both registry descriptions are cut off before their full instructions are given, so the remaining treatment and management details are not reported in the registry record.

Randomization is intended to distribute participant characteristics across groups without relying on investigator choice. Masking is intended to limit the influence of group knowledge on care, outcome assessment, or other trial processes. The registry labels masking as quadruple but does not identify the masked roles or describe how masking was maintained. The parallel-group model means the trial compares groups assigned to different treatment strategies rather than describing a crossover between them.

The primary outcome concerns glucose measured repeatedly: at baseline (T0), then at hour 2 (T1), 4 (T2), 6 (T3), 8 (T4), 10 (T5), and 12 (T6) after the onset of the bolus and infusion. The outcome description says the change from baseline within the first 12 postoperative hours was of interest. The record says all recruited population was analyzed, but does not explain the statistical method used for those repeated measurements or whether every participant contributed measurements at every time point.

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.

Before assignment: No patient was excluded from the study after being assigned to one arm/group.

Overall Study

Analysis population for the primary outcome, as defined in the registry: All recruited population was analyzed.

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.

Population: Baseline characteristics from the entire study population were measured.

6. Primary Endpoint

The registry lists the primary outcome as Plasmatic Glucose Levels (mg/dl)., measured over Baseline levels(T0) and at hour 2(T1), 4(T2), 6(T3), 8(T4), 10(T5), and 12(T6) after the onset of bolus and infusion of dexmedetomidine.

The primary endpoint is plasmatic glucose in mg/dl, recorded at baseline and at six subsequent postoperative time points through hour 12. The registry describes the endpoint as a change of baseline glucose levels within the first 12 postoperative hours. It specifies reporting by mean and standard deviation, but the glucose means and standard deviations are not reported in the registry record.

As a general statistical point, a repeated measure can describe both the level of an outcome at particular times and its pattern over time. Baseline measurement gives a reference for interpreting later measurements, while observations at multiple postoperative times can capture a changing trajectory that a single measurement might miss. Comparisons between randomized groups can address whether their observed patterns differ, but the statistical approach must account for the relationship among repeated observations from the same participant. The analysis method for this endpoint is not reported in the registry record.

Glucose is the outcome named in the trial title and primary outcome entry. The registry does not state a threshold for a clinically important difference, a primary time point selected for the main comparison, or a single summary contrast across the repeated measurements. It also does not report a treatment-effect estimate, confidence interval, or test result for the primary endpoint. Consequently, the endpoint definition can be described, but the magnitude and precision of any between-group finding cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, quadruple-masked, parallel-group design. Random allocation is a design method for reducing systematic differences between treatment groups at the start of a study. In expectation, it balances both measured and unmeasured characteristics, although chance imbalances remain possible, especially in a trial with enrollment of 40. Randomization alone does not guarantee that all participants received the assigned treatment or that outcome data were complete; those details are not reported in the registry record.

Masking can reduce the chance that knowledge of assignment affects treatment, measurement, or reporting. The registry labels the trial quadruple-masked, but does not state which people or roles were masked, how masking was implemented, or whether masking was assessed. The label should therefore be read as the registered design description, not as a complete account of operational procedures.

What does a mean and standard deviation describe?

The primary outcome is specified as a mean with standard deviation. In general, a mean describes the central level of a continuous measurement, while a standard deviation describes how spread out individual measurements are around that mean. The standard deviation is not the same as the uncertainty in a group mean or in a treatment-effect estimate. That inferential uncertainty is commonly expressed with a confidence interval or another standard error-based measure. The registry record does not report the glucose means or standard deviations.

Because glucose was scheduled at baseline and multiple postoperative times, the data have a repeated-measures structure. General methods for repeated measurements account for the fact that values from the same participant are usually more related to one another than values from different participants. A model may estimate time patterns, group differences, or group-by-time contrasts, depending on the chosen specification. The statistical method and target contrast for this trial are not reported in the registry record.

Why does repeated measurement matter?

Repeated measurements can provide a more detailed description of change than a single endpoint, but they also create analytical choices. Investigators may compare groups separately at each time, test an overall pattern, or define a summary across time. These choices affect the interpretation and can affect the number of statistical comparisons. The registry identifies the time points and describes change from baseline, but it does not state which approach was used for the primary analysis.

General statistical practice also considers whether a model’s assumptions fit the data. For example, continuous outcome methods may rely on assumptions about residual distributions and variance structure. If the data are substantially skewed, have unequal variability, or contain influential observations, a simple mean-based analysis may not describe them well. These are general considerations, not claims about this trial’s glucose data; the registry record does not report data distributions or diagnostic checks.

What does a confidence interval add?

As a general concept, a confidence interval conveys uncertainty around an estimated quantity under a specified analysis. It helps readers assess which effect sizes remain compatible with the observed data and assumptions. A point estimate alone does not show precision. For serial glucose outcomes, confidence intervals could be reported for group means, changes, or between-group contrasts, but the interpretation depends on which quantity is estimated. No such estimates or intervals are reported for the primary outcome in the registry record.

A p-value, when reported, addresses compatibility between the data and a specified null hypothesis under the analysis assumptions. It does not convey the size of an effect or its clinical importance. The registry record does not report a primary glucose p-value, so no significance claim can be made from the posted results described in the registry.

How should the planning illustration be understood?

The registry’s sample-size assumptions describe a planning illustration based on the observed effect, not the trial’s own design. The stated assumptions include a two-sided significance level of 0.05, equal allocation between groups, a normal approximation, and an effect to detect defined as a stated fraction of the observed effect. For non-time-to-event outcomes, the illustration is expressed as participants per arm for a target power. This is a planning exercise and must not be interpreted as observed power or evidence about the trial’s result.

General sample-size planning asks how many participants may be needed to detect a specified effect with a chosen error rate and power under stated assumptions. The answer depends on the effect size, variability, allocation, analysis, and outcome structure. The registry record does not report the trial’s own sample-size justification, and the planning illustration does not establish what investigators used when designing the trial. Its numerical outputs are not repeated in this explanation.

The registry lists two analyses, but does not describe their procedures, hypotheses, or relationship to the primary endpoint. It does not state whether models were adjusted for baseline measurements or other covariates, how missing repeated observations were handled, or whether any sensitivity analyses were conducted. Those omissions limit the ability to reproduce or fully evaluate the primary analysis.

10. Multiplicity, Missing Data and Analysis Populations

The primary glucose outcome includes baseline and measurements at hours 2, 4, 6, 8, 10, and 12. Multiple time points create a multiplicity question if each is tested separately. In general, making many statistical comparisons can increase the chance of at least one apparently unusual result under a null model. Researchers may address this through a prespecified primary time point, an overall longitudinal test, an adjustment procedure, or a clearly defined interpretation strategy. The registry record does not report which approach, if any, was used.

The registry lists two analyses, but does not describe their hypotheses, statistical methods, or whether they concern different outcomes or different representations of the primary endpoint. It also does not report any multiplicity adjustment. The appropriate interpretation of multiple outcomes and repeated time points therefore cannot be assessed from the registry record.

The primary outcome entry says all recruited population was analyzed. This identifies the stated analysis population at a broad level, but does not explain whether analysis followed randomized assignment, whether any participants were excluded, or how deviations from assigned treatment were handled. The detailed analysis population and handling of protocol deviations are not reported in the registry record.

Missing outcome data are another concern in longitudinal analyses because a participant may contribute some measurements but not others. General methods include analyses using available observations, model-based approaches, or imputation under explicit assumptions. Each approach relies on assumptions about why values are missing. The registry record does not report the amount or pattern of missing glucose data, how missing values were treated, or whether sensitivity analyses assessed the effect of missingness.

The primary outcome’s reported population statement does not establish that every scheduled glucose value was available for every participant. A complete assessment would require counts at each time point and a description of the analysis set and missing-data method. These details 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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists 20 participants at risk for serious adverse events in each group. It reports zero serious adverse events in the dexmedetomidine group and zero in the 0.9% sodium-chloride group. It also reports zero deaths in each group. These are recorded counts for the registry’s safety categories.

For other adverse events, the registry reports that 17 participants in the dexmedetomidine group and 10 participants in the 0.9% sodium-chloride group were affected, with 20 participants at risk in each group. These figures describe the number of participants recorded in each category. The registry does not provide event names, severity breakdowns, timing, attribution to treatment, or the follow-up rules used for collection. It is therefore not possible to determine from these counts which events occurred or whether they were considered related to either assigned intervention.

Zero recorded serious events does not prove that serious events are impossible or that the groups have identical safety profiles. In general, the interpretation of safety counts depends on the number observed, the number followed, the observation period, and how events were defined and collected. The registry does not report a comparative statistical analysis of these safety figures. They should be read as descriptive registry entries rather than as a definitive estimate of comparative risk.

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

The registry record documents a randomized comparison of dexmedetomidine with 0.9% sodium-chloride in obese patients undergoing bariatric surgery, with serial postoperative glucose as the primary outcome. It supplies the design description, the measurement schedule, and adverse-event counts. It does not report the primary glucose values or the statistical comparison between groups. As a result, the record does not establish whether the observed glucose patterns differed, by how much they may have differed, or how precise any difference was.

The distinction between no reported result and a result showing no difference is essential. A missing estimate cannot be interpreted as a null finding. Without glucose means, change estimates, confidence intervals, or test results, the evidence about the primary endpoint remains unquantified in the registry record. This limitation also prevents assessment of whether any observed difference, if estimated elsewhere, was compatible with a range of effect sizes.

The registered question is specific to the studied perioperative setting and the named population. It does not establish findings for other patient groups, operations, treatment regimens, or longer-term outcomes. The registry also does not report details needed to judge how closely the analyzed population matched the intended population beyond its statement that all recruited participants were analyzed.

The sample-size assumptions describe a planning illustration based on an observed effect and should not be read as proof that the trial had adequate or inadequate power. A planning calculation depends on assumptions, whereas an observed result and its uncertainty depend on the actual outcome data and analysis. The registry record does not report the original sample-size justification or primary glucose analysis needed to evaluate those matters.

The safety counts are limited descriptive information. The absence of recorded serious adverse events and deaths in these entries does not establish the absence of all potential harms, and the other adverse-event counts lack event-level detail. Overall, the registry record allows a clear description of the question and design, but not a conclusion about the primary glucose result or comparative safety beyond the listed counts.

13. Why This Trial Matters Statistically

This trial is statistically notable for pairing random allocation and masking with an outcome measured repeatedly over time. That design raises questions beyond a simple comparison of two endpoint means: the analysis must define how baseline relates to later measurements, how within-participant correlation is handled, and what group contrast is intended. The registry gives the measurement schedule but not the statistical method or result, making the difference between a well-defined outcome and a fully interpretable analysis especially important.

The record also illustrates why outcome registration and outcome reporting serve different purposes. Registration identifies what was planned for measurement, while a report of results is needed to assess estimated effects and their uncertainty. In this case, the registry names glucose as the primary outcome and specifies its timing and summary type, but does not report the numerical glucose results or comparison. Readers can identify the research question without being able to evaluate its answer from the registry record.

Enrollment was 40, with 20 participants at risk for safety reporting in each group. This is useful context for understanding the scope of the trial, but enrollment alone does not determine the precision of a particular outcome estimate. Precision also depends on outcome variability, missingness, analysis choices, and the contrast being estimated. Those elements are not reported for the primary glucose analysis.

The trial’s registered sample-size assumptions are presented as a planning illustration based on the observed effect, not as a reconstruction of the original design decision. That distinction matters because a post hoc planning illustration is not observed power and cannot replace the trial’s actual effect estimate and confidence interval. The original sample-size justification is not reported in the registry record.

More broadly, the record shows why readers should separate design features, outcome definitions, numerical findings, and statistical interpretation. Randomization and masking describe methods; repeated glucose measurements describe the endpoint; adverse-event counts describe safety entries. Without the primary outcome estimates and analysis details, these components do not by themselves yield a quantitative conclusion about the main question.

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 main limitation for interpreting the registered primary question is that glucose results are not reported in the registry record. The record gives no group means or standard deviations, changes from baseline, between-group contrasts, confidence intervals, or p-values. Without those quantities, the direction, magnitude, and precision of the primary outcome comparison cannot be assessed.

The outcome is measured at multiple postoperative times, but the registry does not specify the primary comparison across those measurements. It does not state whether the analysis focused on one time point, compared change from baseline at each time, or tested an overall time pattern. It also does not report how correlation among repeated measurements was handled or whether any multiplicity procedure was used.

The record says all recruited population was analyzed, but does not give an analysis-set definition, participant flow, or counts with available measurements at each time. The extent and handling of missing data, protocol deviations, and departures from assigned treatment are not reported in the registry record. Those omissions matter for assessing how the registered analysis relates to the randomized groups.

The dexmedetomidine and saline arm descriptions are incomplete in the registry record, so the full treatment and management procedures cannot be reconstructed. The record also does not identify the roles covered by quadruple masking or explain how masking was maintained. These limitations concern the detail available in the registry, not proof that procedures were absent.

For safety, the registry provides counts but no event names, severity details beyond the serious-event category, attribution, or event-specific timing. The follow-up period for safety collection is not reported in the registry record. These details constrain interpretation of the reported adverse-event entries.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effect of Dexmedetomidine on Postoperative Glucose and Insulin Levels. — NCT03809182.
• Registry record last updated 2020-10-01; status last verified 2020-09.
• Results first posted 2020-10-01.
• 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 a completed Phase 4 randomized, quadruple-masked, parallel-group trial with enrollment of 40. It compares dexmedetomidine with 0.9% sodium-chloride in obese patients undergoing bariatric surgery. The registered primary outcome is plasmatic glucose in mg/dl, measured at baseline and at hours 2, 4, 6, 8, 10, and 12 after treatment onset.

The registry specifies mean and standard deviation as the primary outcome summary and says all recruited population was analyzed. However, glucose results and the primary statistical comparison are not reported in the registry record. The listed secondary outcomes concern analgesic consumption, pain, sedation-agitation, and postoperative nausea and vomiting; their results are also not reported in the registry record.

Safety entries report zero serious adverse events and zero deaths in each group. Other adverse events affected 17 participants in the dexmedetomidine group and 10 in the 0.9% sodium-chloride group. The registry does not provide event-level details or a comparative safety analysis.