Ketamine and Propofol Combination Versus Propofol for Upper Gastrointestinal Endoscopy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ketamine and Propofol Combination Versus Propofol for Upper Gastrointestinal Endoscopy (NCT02643979), a randomized phase 4 study. The primary outcome is Number of Participants With Gagging Reaction.

2. Clinical Question

The trial record identifies this as a Phase 4, randomized, double-masked, parallel-group study. It records enrollment of 22 participants and a terminated status. The reason for termination is not reported in the registry record. The results therefore describe a small set of observations for the stated primary endpoint, rather than a definitive estimate for every aspect of sedation or respiratory safety. The record does not report an eligibility breakdown or participant-level characteristics that would establish how closely the enrolled group represented the intended population.

3. Trial Design

The registry describes a randomized, double-masked, parallel-group Phase 4 trial comparing ketamine plus propofol with propofol alone during upper gastrointestinal endoscopy. The Ketofol arm received a starting mixture of 50mg of ketamine and 100mg of propofol. The propofol-only arm received 100mg of propofol mixed with 1mL of saline. The registry records 11 participants in each arm for the primary outcome.

Enrollment is recorded as 22, and the study status is terminated. The record does not report why the trial was terminated, whether the enrollment figure reflects the original target, or whether enrollment stopped according to a prespecified plan. The original sample-size justification and design assumptions are not reported in the registry record. The randomized and double-masked labels describe the recorded design, but details of sequence generation, allocation concealment, and how masking was maintained are not reported in the registry record.

The primary outcome was the number of participants with gagging or a “vomit-like” reaction on endoscopic insertion, measured on Day 1. The registry also lists outcomes involving airway obstruction, propofol dose, sedation needed to initiate the procedure, postoperative nausea or vomiting, emergence delirium, and recovery time. Numerical results are recorded for airway obstruction, propofol dose, and sedation needed to initiate the procedure. Numerical results for postoperative nausea or vomiting, emergence delirium, and recovery time are not reported in the registry record.

The trial was sponsored by Icahn School of Medicine at Mount Sinai. The record does not report the statistical analysis plan, analysis populations, or a reason for termination. Those omissions limit what can be concluded about whether the posted summaries represent the originally intended analyses.

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 Number of Participants With Gagging Reaction, measured over Day 1.

The primary endpoint counts participants who had a gagging or “vomit-like” reaction when the endoscope was inserted. It is recorded as a participant count, with Day 1 as the timeframe. In the posted results, this occurred in 2 participants in the Ketofol arm and 1 participant in the propofol-only arm; each arm has 11 participants recorded for this outcome.

A binary event count is useful when the clinical question is whether an event occurred at least once for a participant, rather than how often or how severely it occurred. It gives a direct summary of the proportion experiencing the defined event in each arm. However, the registry does not describe a severity scale, duration, or separate episodes of gagging. The endpoint therefore cannot distinguish a brief reaction from a more consequential one, or describe how frequently repeated reactions occurred.

The endpoint is also narrower than the rationale in the study summary. That rationale discusses sedation, propofol exposure, and spontaneous breathing in people with obesity. Gagging on insertion may be relevant to the procedure, but it is not itself a direct measurement of respiratory function, comfort, or overall sedation quality. The airway-obstruction and medication-dose outcomes address other aspects of the stated rationale, but they are secondary outcomes. The registry record does not report a composite endpoint combining gagging with those outcomes.

Because the endpoint is based on a small number of recorded events, the arm-specific counts and uncertainty around their comparison matter. The risk-difference interval includes values favoring either arm, so the observed difference should not be treated as a precise estimate of the underlying difference in gagging risk.

7. Results Posted in the Registry

• Propofol Only: 9.1% (1/11) versus 18.2% (2/11) on control; risk difference -9.1 percentage points (95% CI -37.5 to 19.3), risk ratio 0.50 (0.05–4.75); unadjusted two-proportion z-test p = 0.534.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Number of Participants With Any Type of Airway Obstruction

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Propofol Only: 27.3% (3/11) versus 36.4% (4/11) on control; risk difference -9.1 percentage points (95% CI -47.8 to 29.6), risk ratio 0.75 (0.22–2.60); unadjusted two-proportion z-test p = 0.647.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Propofol Only and the control. The interval gives the range of effects that remain compatible with the data.

Total Dose of Propofol Used During the Procedure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Propofol Only: mean 39.00 versus 9.09 on control; difference 29.91 (95% CI -5.76 to 65.58), standardized effect d = 0.70; z-test p = 0.100.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Propofol Only and the control. The interval gives the range of effects that remain compatible with the data.

Total Sedation Required to Allow Initiation of Procedure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Propofol Only: mean 61.00 versus 78.00 on control; difference -17.00 (95% CI -62.13 to 28.13), standardized effect d = -0.31; z-test p = 0.460.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Propofol Only and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes provide additional, but incomplete, information about the sedation rationale. The airway-obstruction counts are close in the two arms, while the continuous summaries show a lower recorded mean total propofol dose in the Ketofol arm and a higher mean amount of sedation required to initiate the procedure in that arm. None of those patterns resolves the primary endpoint’s uncertainty or establishes a clear overall difference between regimens. The confidence intervals for the posted comparisons are broad, and the registry does not provide numerical results for every outcome it lists.

These endpoints relate to different parts of the clinical rationale. Airway obstruction is relevant to the concern about breathing during propofol sedation. Propofol dose addresses the possibility of reducing exposure to that drug, while sedation needed to initiate the procedure relates to the amount required to begin the procedure. Gagging is a distinct procedural response. A pattern in one measure cannot be assumed to imply a corresponding pattern in another, and the registry does not report an overall composite that combines them.

Postoperative nausea or vomiting, emergence delirium, and time to recovery are listed as secondary outcomes, but their numerical results are not reported in the registry record. Their absence from the posted numerical results means they cannot be used to assess whether the arms differed on those outcomes.

Secondary findings usually carry less weight than a prespecified primary result because many outcomes may be examined, raising the chance that some differences appear notable by chance. The registry does not report whether these secondary analyses were prespecified in detail or how multiplicity was handled. Their p-values are unadjusted. They should therefore be treated as exploratory context rather than as independent confirmation of the primary comparison or of the broader rationale.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Number of Participants With Any Type of Airway Obstruction
• Total Dose of Propofol Used During the Procedure
• Total Sedation Required to Allow Initiation of Procedure
• Number of Participants With Post-operative Nausea and/or Vomiting
• Number of Participants With Emergence Delirium
• Time to Recovery

9. Statistical Interpretation

10. Statistical Methods Explained

The posted comparisons use summaries of outcomes in the two randomized arms. For a binary outcome, such as whether a participant had gagging, each participant is counted as having or not having the event. The event count and the number of participants recorded in each arm determine the observed event proportion. A risk difference expresses the subtraction of one arm’s event proportion from the other. The primary comparison is reported as propofol-only risk minus Ketofol risk; a negative estimate therefore means the observed risk was lower in the propofol-only arm.

What does a confidence interval describe?

In general, a confidence interval describes the range of values reasonably compatible with the observed data under the statistical method used. It is not a guarantee that the true effect lies within the interval, nor is it a range of likely individual outcomes. A wide interval indicates limited precision: the data are compatible with a broad range of underlying effects. For the primary risk difference, the interval extends from -0.375 to 0.193. Because it includes zero and values on both sides of zero, it does not establish a direction for the underlying difference.

The registry also reports relative measures for the primary comparison: a risk ratio of 0.5 with an interval from 0.053 to 4.745, and an odds ratio of 0.45 with an interval from 0.035 to 5.843. A risk ratio compares the event proportions in the arms; an odds ratio compares event odds. Both are relative scales, whereas the risk difference is an absolute scale. These relative intervals are also broad. With sparse event counts, relative estimates can be especially imprecise and should be read alongside the arm-specific counts and the absolute risk difference.

How should the p-value be read?

In general, a p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the statistical model were correct. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. The primary unadjusted p-value is 0.534. That value does not establish that the arms have identical risks, especially given the broad confidence interval and limited number of recorded events.

For continuous outcomes, the registry reports arm-specific means and standard deviations, along with mean differences and confidence intervals. A mean summarizes the arithmetic center of the recorded values. A standard deviation describes the spread of values around that mean; it is not the uncertainty interval for the mean itself. The total propofol-dose means are 9.09 mg/kg for Ketofol and 39.0 mg/kg for propofol only, with standard deviations of 19.0 and 57.3. The mean difference is 29.91 mg/kg, with an interval from -5.765 to 65.58. The direction of that difference is propofol-only mean minus Ketofol mean.

For sedation required to initiate the procedure, the recorded means are 78 mg/kg for Ketofol and 61 mg/kg for propofol only. The mean difference is -17.0 mg/kg, with an interval from -62.13 to 28.13, again defined as propofol-only mean minus Ketofol mean. Both continuous-outcome intervals include zero. These summaries do not show a precisely estimated difference. The registry records standard deviations, but does not report whether the continuous outcome distributions were examined for skew or other departures from assumptions.

Why does over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model expects. For count data, ignoring over-dispersion can make standard errors too small and confidence intervals too narrow, creating more apparent precision than the data justify. The primary and airway outcomes are recorded as participant counts, not as repeated event rates, and the registry does not report a count-rate model or an over-dispersion assessment. It is therefore not appropriate to infer that a particular over-dispersion correction was used.

The reported comparisons are unadjusted. The record does not describe covariate adjustment, a stratification scheme, or an analysis method for the primary comparison. It also does not report any formal statistical analyses in the registry analysis listing. The posted estimates can be read as simple comparisons of the summarized arms, but the specific inferential procedure behind each interval and p-value is not described. General statistical interpretation should not be confused with a claim about an unreported analysis plan.

Finally, the registry includes sample-size planning illustrations based on observed effects. These are prospective planning calculations under stated assumptions; they are not observed power and do not replace the original trial’s design rationale. The original sample-size justification, interim-analysis plan, handling of missing data, and multiplicity strategy are not reported in the registry record. Those omissions make it difficult to determine how closely the posted summaries follow the trial’s intended statistical approach.

11. Confidence Intervals and Precision

The primary risk-difference estimate is -0.091, with a 95% confidence interval from -0.375 to 0.193. The interval spans zero and both negative and positive differences. In practical terms, the observed data are compatible with a lower event risk in the propofol-only arm, little or no difference, or a higher event risk in that arm. The data do not identify one of these possibilities with precision.

The small event counts are central to this uncertainty: gagging was recorded for 2 participants in the Ketofol arm and 1 participant in the propofol-only arm. When few events occur, changing the event status of even a small number of participants can materially alter the estimated comparison. The relative estimates are likewise imprecise: the risk ratio is 0.5 with a 95% confidence interval from 0.053 to 4.745, and the odds ratio is 0.45 with a 95% confidence interval from 0.035 to 5.843.

The continuous secondary comparisons also have intervals that include zero. For total propofol dose, the mean-difference interval runs from -5.765 to 65.58 mg/kg. For sedation required to initiate the procedure, it runs from -62.13 to 28.13 mg/kg. These ranges indicate that the posted summaries do not give a precise estimate of the differences in those outcomes either. Confidence intervals describe uncertainty in the estimated arm contrast, not the spread of individual participants’ outcomes; the standard deviations describe that separate within-arm spread.

Precision should not be confused with whether a result is statistically significant. A nonsignificant p-value does not demonstrate equivalence, while a confidence interval shows the range of effects compatible with the data under the method used. No clinical threshold for an important difference is reported in the registry record, so the estimates cannot be judged against a stated threshold for importance.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations of how many participants per arm might be needed under the stated assumptions to detect a selected fraction of the observed effect. The calculations assume a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. They use the observed effect as their reference and consider planning for 100%, 75%, or 50% of that effect. These are planning assumptions for the illustrations, not the trial’s original design assumptions; the original sample-size justification is not reported in the registry record.

The 80% power column describes the planned chance of detecting the specified effect if that effect is the true one and the assumptions of the calculation hold. The 90% power column uses a higher target chance of detecting that effect, so it generally requires more participants per arm. A smaller effect is harder to distinguish from random variation, so planning for a smaller fraction of the observed effect requires more participants per arm. The figures vary by outcome because the underlying observed effects and variability differ.

For the outcomes in this trial, the planning figures are stated as participants per arm, not as total events. The sample-size assumptions distinguish these values from time-to-event calculations, which would be expressed as total events; no time-to-event outcome is presented among the reported results.

These calculations do not show the probability that the completed trial found a real effect, and they do not indicate whether the completed trial was adequately powered. This is not observed power. The actual record reports 11 participants in each arm for the primary endpoint, but the registry does not report the trial’s original target, its sample-size rationale, or whether a planned enrollment target was changed.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.182; treatment proportion p₁ = 0.091; average p̄ = 0.136.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.4853 = 0.9512.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.4810 = 0.4049.
4. n = (0.9512 + 0.4049)² / (-0.0909)² = 222.5, rounded up to 223 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.181818181818182                          # control proportion
p1 <- 0.0909090909090909                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(2643979)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 223 (80% power), 298 (90% power)
 75% of observed effect: n per arm = 424 (80% power), 568 (90% power)
 50% of observed effect: n per arm = 1,016 (80% power), 1,359 (90% power)
power.prop.test: 222.5 
Simulated power at n = 223 per arm: 0.808 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary endpoint and lists several secondary outcomes, but it does not report a plan for controlling multiplicity. When investigators examine multiple outcomes, each test creates an opportunity for a chance finding. If no adjustment or hierarchy is prespecified, unadjusted p-values for secondary outcomes do not account for the number of comparisons made. The reported secondary p-values should therefore be interpreted cautiously; the record does not establish that any one secondary finding was confirmatory.

The registry analysis listing contains no reported analyses. The record does not describe which analysis population was used, whether all randomized participants were included, or how participants with missing outcome data were handled. It also does not report whether analysis followed an intention-to-treat approach, a per-protocol approach, or another defined population. These details matter because exclusions or missing observations can affect how well a comparison preserves the benefits of randomization.

The record does not report a statistical analysis plan, the method used to generate the primary confidence interval and p-value, covariate adjustments, or whether there were interim analyses. The absence of these details does not show that such procedures were or were not carried out; it means they are not documented in the registry record. Likewise, the reason the trial was terminated and any consequences for the analysis are not reported.

For continuous outcomes, the record provides means and standard deviations but does not describe the analysis model, checks of distributional assumptions, or handling of extreme observations. For binary outcomes, it does not state whether the inferential procedure was selected to account for the small event counts. These omissions limit evaluation of the reported uncertainty and of the alignment between the analyses and the original design.

Accordingly, the primary result is best read as the posted comparison for the defined endpoint, with the secondary results as unadjusted supporting descriptions. The registry does not provide enough information to assess a complete multiplicity strategy, missing-data procedure, or analysis-population definition.

15. 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.

The serious adverse event summary records 0 serious adverse events in the Ketofol and propofol arm and 0 in the propofol-only arm. It also records 0 deaths in each arm. Each safety group has 11 participants listed at risk for serious adverse events.

A recorded zero means that no serious adverse events or deaths are reported for these groups in the registry summary. It does not demonstrate that the risk is absent. With a small number of participants, uncommon events may not be observed even if they can occur, and the data cannot tightly estimate rare-event risks. The registry’s serious-adverse-event summary should therefore be read as a report of what was recorded, not as proof of safety or a comparison establishing equal risk.

The registry lists no top serious adverse-event terms. The record does not provide additional detail in this summary about how adverse events were collected, how long participants were followed for safety, or whether non-serious adverse events were assessed comprehensively. The listed secondary outcomes include postoperative nausea or vomiting and emergence delirium, but numerical results for those outcomes are not reported in the registry record. They should not be inferred from the serious adverse-event counts.

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

The primary result describes a small observed difference in the number of participants with gagging or a “vomit-like” reaction during endoscope insertion. The event was recorded for 2 participants receiving Ketofol and 1 receiving propofol only. The estimated risk difference is -0.091 for propofol only minus Ketofol, with a 95% confidence interval from -0.375 to 0.193. That interval is compatible with effects in either direction and does not provide a precise estimate of the underlying difference.

The finding does not establish that the regimens are equivalent, that one regimen is better, or that either regimen changes respiratory safety. No equivalence margin is reported, and gagging is not a direct measure of respiratory function. The airway-obstruction outcome is a separate secondary measure and its posted comparison is also uncertain. The lower mean propofol dose recorded in the Ketofol arm is consistent with the stated possibility that ketamine could reduce propofol use, but that observation alone does not show that spontaneous breathing was maintained or improved.

The record also does not support a conclusion about every outcome in the study rationale. Numerical results for postoperative nausea or vomiting, emergence delirium, and recovery time are not reported in the registry record. The safety summary records no serious adverse events or deaths in either arm, but those observations do not rule out uncommon harms or establish comparable safety.

More broadly, this is a terminated trial with enrollment recorded as 22. The reason for termination, the original sample-size target, and the analysis plan are not reported in the registry record. Those limitations, together with the wide intervals, call for interpreting the estimates as uncertain summaries of the posted data. They do not provide a basis for medical advice or a general conclusion about sedation in all patients undergoing endoscopy.

17. Why This Trial Matters Statistically

This trial is statistically instructive because the observed direction of a difference and the certainty of that difference are separate matters. The primary event count is numerically higher in the Ketofol arm, but the risk-difference interval is broad and includes values on both sides of zero. A point estimate alone would conceal how much uncertainty remains. Looking at the interval alongside the arm-specific counts makes the limited precision clear.

The results also illustrate why a nonsignificant p-value is not evidence of equivalence. The primary unadjusted p-value is 0.534, but the registry does not report an equivalence or noninferiority design or a margin defining an acceptable difference. A failure to reject a null hypothesis cannot answer whether two regimens are sufficiently similar for a particular purpose.

The distinction between outcomes matters as well. The rationale concerns sedation, propofol exposure, and breathing, while the primary endpoint is gagging during insertion. Secondary outcomes address pieces of that broader rationale, but they are not substitutes for the primary endpoint and their results are less secure when multiplicity handling is not reported. The incomplete set of numerical secondary results further limits synthesis across outcomes.

Finally, planning estimates based on observed effects can show how assumptions about effect size and desired power influence future sample-size needs. They cannot retrospectively establish the power of this completed study. The original design rationale is not reported, so the registry’s planning illustrations should remain separate from claims about the trial’s intended or achieved power.

18. 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 primary comparison is based on 11 participants in each arm and only a small number of recorded gagging events. This limits precision, as reflected in the wide risk-difference interval. The trial’s terminated status adds uncertainty about the context of the results: the reason for termination, whether recruitment followed the original plan, and whether termination affected the analyses are not reported in the registry record.

The intended population is described as people with obesity, but the results record does not provide participant characteristics or a clear account of the enrolled population. It therefore does not establish how well the observed results apply across the intended population or to other endoscopy settings. Details about eligibility, procedure characteristics, and adherence to the assigned regimen are not reported in the results record.

The registry does not report the original sample-size justification, the statistical analysis plan, the analysis populations, the handling of missing data, or the multiplicity strategy. It also does not provide numerical results for all listed secondary outcomes. These gaps prevent a full assessment of whether the posted comparisons reflect the planned analyses and whether outcome reporting is complete.

The primary endpoint captures whether gagging occurred, not its severity, duration, or consequences. It does not directly quantify spontaneous breathing or overall comfort. The secondary airway and dose outcomes offer relevant but separate information; their uncertainty and the lack of a reported analysis plan limit broader conclusions. Finally, the serious-adverse-event summary records no events, but a small study cannot rule out uncommon events, and details of safety follow-up are not reported in the registry record.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Ketamine and Propofol Combination Versus Propofol for Upper Gastrointestinal Endoscopy — NCT02643979.
• Registry record last updated 2020-02-11; status last verified 2020-01.
• Results first posted 2020-01-28.
• 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.

22. Record Summary

The registry record describes a Phase 4, randomized, double-masked, parallel-group trial of ketamine plus propofol versus propofol alone during upper gastrointestinal endoscopy. It records enrollment of 22 and a terminated status. The reason for termination is not reported in the registry record.

The primary outcome was the number of participants with gagging or a “vomit-like” reaction on insertion, measured on Day 1. This was recorded for 2 participants in the Ketofol arm and 1 participant in the propofol-only arm. The risk-difference estimate is -0.091, with a 95% confidence interval from -0.375 to 0.193. The broad interval indicates substantial uncertainty.

Results are also recorded for airway obstruction, propofol dose, and sedation needed to initiate the procedure. Numerical results for postoperative nausea or vomiting, emergence delirium, and recovery time are not reported in the registry record. The safety summary records no serious adverse events or deaths in either arm. Original sample-size justification, analysis populations, missing-data methods, and multiplicity handling are not reported.