This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Effects of Low Dose Ketamine Given at Induction of Anesthesia on Postoperative Mood in Patients With Depressive Symptoms (NCT02422303), a randomized na study. The primary outcome is Depression Score Using Goldberg Depression Screening Test.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02422303 |
| Phase | NA |
| Condition | Depression, Major Depressive Disorder |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | The University of Texas Health Science Center at San Antonio |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned surgical patients with depressive symptoms. The listed conditions are Depression and Major Depressive Disorder. The registry record does not report further eligibility details, such as how depressive symptoms were established for enrollment or what surgical procedures were included.
Intervention
The ketamine group was to receive ketamine at 0.5mg/kg intravenously at induction of general anesthesia. The registry summary explains that the study was intended to examine whether a dose used in this setting might affect postoperative mood in surgical patients with depression.
Comparator
The no-ketamine group was not to receive ketamine at induction of general anesthesia. The record does not describe a placebo or another substitute intervention, so the comparison should be understood as ketamine versus no ketamine at induction, as specified in the arm descriptions.
Primary question
The primary outcome was the Goldberg Depression Screening Test score, with the registry listing a timeframe of one week. The clinical question was whether the groups’ postoperative depression scores differed. Participant data were destroyed at study termination, however, and the registry states that no analysis was performed. It therefore contains no estimated group difference or other primary-outcome result with which to answer that question.
3. Trial Design
The registry describes a randomized, double-masked, parallel-group trial. Participants were assigned to a ketamine group or a no-ketamine group. The ketamine arm description specifies 0.5mg/kg intravenously at induction of general anesthesia; the comparator arm description says ketamine was not given at induction. The record does not describe a placebo, the randomization procedure, or how masking was maintained.
The listed enrollment is 12. The trial is marked terminated, and its listed start and primary-completion dates are 2015-12 and 2016-09. The registry lists the phase as NA and identifies The University of Texas Health Science Center at San Antonio as sponsor. It does not report why the trial was terminated or whether termination occurred as planned.
One primary outcome measure is listed: the Goldberg Depression Screening Test score, with a timeframe of one week. Although the record describes the scale and its score bands, participant data were destroyed at termination and no analysis was performed. Thus, the design description documents the intended comparison and outcome, not an evaluated treatment effect. Details such as the allocation sequence, recruitment and follow-up procedures, statistical analysis plan, and reasons for ending the study 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
| Stage | Ketamine Group | No Ketamine Group |
|---|---|---|
| STARTED | 6 | 6 |
| COMPLETED | 5 | 5 |
| NOT COMPLETED | 1 | 1 |
Reasons for not completing this period:
| Reason | Ketamine Group | No Ketamine Group |
|---|---|---|
| Lost to Follow-up | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: Participant data were destroyed at study termination, and no analysis was performed, since no longer available.
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.
| Characteristic | Unit | Ketamine Group | No Ketamine Group | Total |
|---|---|---|---|---|
| Participants analysed | 6 | 6 | 12 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 6 | 6 | 12 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 6 | 6 | 12 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | Participants | 5 | 5 | 10 |
6. Primary Endpoint
The registry lists the primary outcome as Depression Score Using Goldberg Depression Screening Test, measured over One week.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the depression score from the Goldberg Depression Screening Test, with the registry listing a timeframe of one week. The test is described as 18 questions answered with reference to the previous 10-14 days. Each response is scored from 0, “not at all,” to 5, “very much,” with intermediate response labels also listed. The registry says the scores are summed and interpreted using bands: 0 - 9, no depression likely; 10 - 21, possible symptoms that may be due to depression or other medical issues; 22 - 35, mild to moderate depression; 36 - 53, moderate to severe depression; and 54 and up, severely depressed. It states that higher scores indicate more severe depression is likely.
A depression screening score is relevant to the trial’s stated question because it offers a structured measure of reported depressive symptoms after surgery. The registry does not report the score unit or a more specific assessment schedule beyond “One week.” It also does not report whether the intended comparison concerned change from a baseline score or scores measured at follow-up. Most importantly, the participant data were destroyed and no analysis was performed, so there are no observed endpoint scores or group comparison results in the record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record does not provide an analyzed primary-outcome result. It states that participant data were destroyed at study termination and that no analysis was performed, since the data were no longer available. Consequently, there is no reported group mean, score distribution, treatment-effect estimate, confidence interval, or significance test for the Goldberg Depression Screening Test. The clinical question remains unanswered by the posted results.
The planned comparison was ketamine at induction of general anesthesia versus no ketamine at induction, among surgical patients with depressive symptoms. The listed primary outcome was a Goldberg screening score with a one-week timeframe. These design details describe what the trial set out to examine; they do not establish what happened to participants’ scores. Without analyzed outcome data, it is not possible to characterize the direction, size, or precision of a group difference.
Enrollment is listed as 12, but that figure alone cannot show how many participants contributed primary-outcome data or whether any were assessed at the stated timeframe. The record explicitly says participant data were destroyed and no analysis was performed. No outcome estimate can therefore be recovered from the enrollment entry or from the arm descriptions. The registry record does not report a reason for termination, the planned analysis, or whether the study stopped before any outcome assessments were completed.
The safety entries are separate from the missing mood outcome. They list zero serious adverse events and zero other adverse events among the participants at risk in each arm, but these counts do not provide evidence about the depression scores. Nor do they establish that no adverse events occurred outside the categories or observations recorded. Death counts are not reported in the registry record.
In statistical terms, the main limitation is not a wide or inconclusive estimate; it is the absence of an estimate. A confidence interval could describe the uncertainty around an analyzed effect, but none is available. A nonsignificant test, a small effect, and a precise estimate near no difference are not interchangeable with an outcome that was never analyzed. The record supports a description of the intended trial and its unavailable results, not a conclusion about the effect of ketamine on postoperative mood.
9. Statistical Methods Explained
The registry identifies a randomized, double-masked, parallel-group design. These terms describe intended features of the comparison, but they do not substitute for the results. Random allocation is a method for assigning participants to treatment groups so that, in expectation, the groups are comparable with respect to characteristics that may affect outcomes. Masking is intended to limit the influence of knowing an assignment on care, assessment, or interpretation. The record does not describe the random sequence, concealment procedure, or how masking was maintained, so those implementation details are not available.
What does a parallel-group comparison estimate?
In a parallel design, participants are assigned to one group and assessed in that assigned group rather than crossing over between interventions. This trial listed ketamine at induction in one arm and no ketamine at induction in the other. A comparison of outcome scores could estimate how the groups differed on the recorded endpoint, subject to the study’s eligibility, conduct, outcome measurement, and analysis. No such estimate is reported because the participant data were destroyed and no analysis was performed.
How should the score be understood?
The listed outcome is a sum of responses to the Goldberg Depression Screening Test. A summed score preserves more gradation than a label alone, while the listed score bands give a screening-oriented interpretation of ranges. Such bands do not themselves report a treatment effect. To compare groups, an analysis would need to specify how the scores are summarized and contrasted, and whether the comparison uses follow-up scores, change from baseline, or another approach. Those analytical details are not reported in the registry record. The record also does not give observed scores, so neither the score distribution nor the location of either group within the stated bands can be described.
What would an estimate and confidence interval contribute?
General statistical explanation: an effect estimate expresses the observed contrast between groups using a defined measure, such as a difference in average scores. A confidence interval expresses the precision of that estimate under the assumptions of the method. An interval that is wide indicates that the data are compatible with a broad range of effects; a narrow interval indicates greater precision. Neither an estimate nor an interval is available for this trial’s primary outcome. The absence of those quantities is not evidence that the groups had equal scores, and it does not establish that any possible difference was clinically important or unimportant.
Why does the missing analysis matter?
Statistical inference depends on outcome observations and a specified analysis. Enrollment describes the number recorded as enrolled, not the number with usable endpoint data. In this case, the registry specifically reports that participant data were destroyed and no analysis was performed because they were no longer available. This prevents assessment of the primary outcome and also prevents checking how missing observations, baseline measures, or deviations from the planned assignment were handled. The record does not report an analysis population or an intention-to-treat analysis.
General statistical explanation: a study’s ability to detect an effect depends on factors including the amount of outcome information, variability, the effect size, and the analysis method. A small study can yield an imprecise estimate even when the analysis is valid, while a larger study can still be uninformative if outcome data are unavailable or measurements are poorly defined. Here, the obstacle is definitive for the posted primary result: there is no reported analysis from which to estimate an effect or its precision. The registry does not report a sample-size justification, statistical power calculation, interim analysis, or prespecified statistical plan. Those details cannot be inferred from the design label or enrollment entry.
What can the safety counts establish?
General statistical explanation: an event count should be interpreted alongside the population at risk, event definitions, follow-up, and completeness of reporting. A recorded zero means no events were recorded in that category among the stated at-risk group; it does not by itself prove that an event is impossible or that the intervention has no safety risks. The registry lists zero serious and zero other adverse events in each arm, with six participants at risk in each arm for each category. These entries do not replace the unavailable mood analysis. The record does not report deaths, as distinct from recording a count of zero, or provide further safety-analysis details.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure, the Goldberg Depression Screening Test score, with a timeframe of one week. It does not report a statistical analysis plan or whether additional outcomes, time points, subgroup comparisons, or repeated analyses were planned. No multiplicity adjustment is reported. When multiple outcomes or comparisons are tested, the chance of finding at least one apparently notable result can increase; methods to address that issue depend on the prespecified analysis. In this record, no primary-outcome analysis is available, so there are no reported tests or estimates for which to evaluate multiplicity.
The record states that participant data were destroyed at study termination and that no analysis was performed because the data were no longer available. This is not simply a report that some observations were missing from an otherwise analyzed dataset. The registry gives no account of endpoint completion, withdrawals, reasons for missing assessments, or whether any partial data remained before destruction. It does not report an imputation method or a sensitivity analysis.
The analysis population is also not reported in the registry record. There is no statement about whether participants would have been analyzed according to randomized assignment, according to treatment received, or under another rule. The enrollment entry should not be mistaken for the number contributing to an outcome analysis. Without available participant data and an analysis, neither the impact of missing outcomes nor the robustness of a treatment estimate can be assessed.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Ketamine Group | 0 | 6 | 0.0% |
| No Ketamine Group | 0 | 6 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Ketamine Group | 0 of 6 |
| No Ketamine Group | 0 of 6 |
The registry lists zero serious adverse events among six participants at risk in the Ketamine Group and zero among six participants at risk in the No Ketamine Group. It also lists zero other adverse events among six participants at risk in each group. No serious adverse-event terms are listed. These entries describe the recorded counts in the categories presented; they are not results for the depression-score endpoint.
A recorded zero should be read as no event recorded for that category and at-risk group in the registry entry. It is not proof that no event occurred, that reporting was complete, or that the intervention is free of safety concerns. The record does not describe the adverse-event collection procedures, definitions, observation period, or completeness of follow-up. Death counts are not reported in the registry record; a blank or unavailable count is not the same as a reported zero. Given that participant data were destroyed and no analysis was performed, these sparse safety entries should be interpreted narrowly and should not be extended to claims beyond the reported counts.
12. What the Result Does, and Does Not, Mean
This record establishes that a randomized, double-masked, parallel-group trial was designed to compare ketamine at induction of general anesthesia with no ketamine at induction in surgical patients with depressive symptoms. It identifies a primary outcome, the Goldberg Depression Screening Test score, and lists a one-week timeframe. It also records enrollment of 12 and a terminated status. These registry entries describe the study’s design and record status.
The record does not establish whether ketamine changed postoperative mood. The primary-outcome data were destroyed at termination, and no analysis was performed. There is consequently no reported score contrast, effect estimate, confidence interval, or statistical test. This is not a finding of no difference; it is an absence of an analyzed result. It is also not possible to judge the magnitude or precision of any potential difference from the information recorded.
The safety counts show zero recorded serious and other adverse events in the listed at-risk groups, but the registry does not provide enough detail to treat these counts as a comprehensive assessment of safety. They do not answer the primary mood question or establish the absence of risk. Death counts are not reported in the registry record.
Readers can use the record to understand what comparison and outcome were intended, and why no primary result is available. They should not treat the trial as evidence for or against a mood effect, infer a result from the sample size, or interpret missing analysis as a negative finding. Reasons for termination, the statistical plan, and details of outcome completion are not reported, so the record cannot resolve those uncertainties.
13. Why This Trial Matters Statistically
This trial illustrates why registration details and analyzed results answer different questions. A registry record can document the population of interest, assigned interventions, comparator, and intended endpoint. Those details help define a research question. They do not establish an effect unless outcome observations are available and analyzed. Here, the record describes a randomized, double-masked comparison and a screening-score outcome, but reports that participant data were destroyed and no analysis was performed.
The distinction matters because a missing result should not be treated as a null result. Statistical interpretation normally depends on an estimate and its uncertainty, together with a clear account of the analysis population and outcome measurement. This record provides none of those for the primary endpoint. It is therefore not possible to distinguish a small effect from a large but imprecisely estimated effect, or either from no difference. Those possibilities cannot be resolved by the trial design description alone.
The record also shows the limits of sparse safety reporting. Zero recorded events in the listed categories are useful descriptive entries, but without detail on ascertainment and follow-up they do not support broad conclusions. More generally, complete reporting of data availability, analysis methods, outcome completion, and reasons for termination is important for readers to understand what can and cannot be learned from a trial.
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 central limitation is that the participant data were destroyed at study termination and no analysis was performed. As a result, the registry has no analyzed primary-outcome scores, no comparison between groups, and no estimate of uncertainty. This prevents an assessment of the intended postoperative mood question.
The registry does not report why the study was terminated, whether outcome assessments had been completed before termination, or how many participants would have contributed data to the primary endpoint. Although enrollment is listed as 12, this does not establish endpoint availability. The record also does not report baseline depression scores, the specific assessment procedure, or whether the intended analysis would have assessed follow-up score or change from baseline.
Important design and analysis details are not reported in the registry record, including the randomization procedure, how masking was maintained, the statistical analysis plan, a sample-size justification, and the analysis population. The record does not describe recruitment procedures, participant characteristics beyond the listed conditions, or the surgical settings. These omissions limit assessment of trial conduct and of how broadly its intended question might apply.
The safety entries list zero serious and other adverse events in the stated at-risk groups, but the record does not describe event definitions, ascertainment, or follow-up completeness. Death counts are not reported. These limitations mean that the listed counts cannot support a comprehensive safety interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effects of Low Dose Ketamine Given at Induction of Anesthesia on Postoperative Mood in Patients With Depressive Symptoms — NCT02422303.
- Registry record last updated 2018-02-15; status last verified 2016-09.
- Results first posted 2018-02-15.
- 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.
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18. Record Summary
The registry describes NCT02422303 as a randomized, double-masked, parallel-group trial of ketamine at induction of general anesthesia versus no ketamine at induction in surgical patients with depressive symptoms. The ketamine arm was to receive 0.5mg/kg intravenously. The listed primary outcome was the Goldberg Depression Screening Test score, with a timeframe of one week. Enrollment is listed as 12; the trial is marked terminated.
The registry states that participant data were destroyed at termination and no analysis was performed. No primary-outcome effect estimate or statistical test is reported. Safety entries list zero serious and zero other adverse events in each arm among six participants at risk per category; death counts are not reported. The record does not report the reason for termination or the statistical analysis plan.