Conscious Sedation for Epilepsy Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Conscious Sedation for Epilepsy Surgery (NCT02988050), a randomized na study. The primary outcome is Patients Satisfaction.

2. Clinical Question

The registry describes a randomized, double-masked, parallel-group trial. Its brief summary says that sedation scores, patient and surgeon satisfaction, heart rate, mean arterial blood pressure, oxygen saturation, and several side effects were recorded. The posted primary outcome is patient satisfaction; the additional measures are not posted as secondary results in the registry record.

The comparison is about the recorded score and its uncertainty, not about whether either regimen is medically preferable. The group means are close, while the confidence interval for their difference includes values on either side of zero. That interval is important: the point estimate alone does not convey how imprecisely the difference is estimated.

3. Trial Design

The registry identifies NCT02988050 as a completed randomized, double-masked, parallel-group trial of conscious sedation for epilepsy surgery. The listed condition is epilepsy, and the sponsor is Menoufia University. The registry lists the phase as NA. The record gives a start date of 2013-08 and a primary completion date of 2016-02.

The brief summary describes 60 patients randomly allocated to two groups, with 30 patients in each group. One group received propofol and dexmedetomidine intravenous infusion; the other received propofol and remifentanil intravenous infusion. The arm descriptions also list bupivacaine and lidocaine as local anaesthetics and epinephrine with local anaesthetics for skin infiltration. For the primary outcome, however, the reported group names are Conscious sedation1 and Conscious sedation2. The registry record does not explicitly connect those outcome labels to the named regimens in the posted outcome results.

Double masking indicates that the registry characterizes the trial as masked for two parties, but the identities of those parties and the practical masking procedures are not reported in the registry record. The allocation method beyond randomization, the method used to conceal allocation, and details of how the parallel groups were managed are also not reported.

The registry describes satisfaction as the primary outcome, assessed one hour after the operation. It records a mean and standard deviation for each group. The record lists one outcome measure and no posted secondary outcomes. It does not report the trial’s original sample-size assumptions, a detailed statistical analysis plan, or the analysis population used for the outcome. These omissions limit what can be inferred about how the trial was planned and how the posted summaries were produced.

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: Patients were excluded if they refused to be included in the study.

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 Patients Satisfaction, measured over 1 hour after the operation.

The primary endpoint is patient satisfaction, recorded one hour after the operation. The registry describes a score ranging from 0 for not satisfied to 10 for totally satisfied. The posted summaries report a group mean and standard deviation, treating the score as a continuous measure.

A satisfaction score captures the patient’s reported experience of the procedure and sedation at the specified assessment time. A group mean gives a concise description of the average score, while the standard deviation describes how much scores vary among patients within that group. These summaries can help readers understand both the overall level of reported satisfaction and the spread of individual scores.

As a general statistical point, an endpoint should be interpreted in light of how it was measured and when it was assessed. Here, the time point is one hour after the operation, and the scale endpoints are described in the registry. Other properties of the measure—such as validation, the handling of missing responses, and whether any score threshold was prespecified—are not reported in the registry record.

The endpoint is not a direct measure of every aspect of sedation, surgical experience, or clinical outcome. Although the brief summary mentions additional measures, no secondary outcome results are posted in the registry record. The satisfaction result therefore addresses the stated score at the stated time, rather than establishing a broader account of all outcomes associated with either regimen.

7. Results Posted in the Registry

• Conscious sedation2: mean 6.45 versus 6.33 on control; difference 0.12 (95% CI -0.58 to 0.82), standardized effect d = 0.09; z-test p = 0.737.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is summarized as a mean with a standard deviation because the registry classifies it as a continuous measure. The mean describes the average recorded satisfaction score within each group. The standard deviation describes the dispersion of scores around that mean; it is not the uncertainty in the estimated group mean and is not a confidence interval.

The posted comparison is a mean difference, with Conscious sedation1 serving as the reference group and Conscious sedation2 as the comparison group. The group means are 6.33 and 6.45, and the reported difference is 0.12. A mean difference keeps the result on the original satisfaction-score scale, which can make it easier to relate to the stated scale from 0 to 10. The comparison also reports a standardized difference, d = 0.087. As a general statistical concept, standardization expresses a difference relative to variability, allowing an effect to be described without retaining the original measurement units. It does not by itself indicate whether an effect matters to patients.

What does the confidence interval convey?

The reported 95% confidence interval extends from -0.581 to 0.821. In general, a confidence interval is a range produced by a statistical method that reflects uncertainty about an estimated quantity. Its interpretation depends on the method and assumptions used. The interval includes zero, so the data do not clearly distinguish a positive mean difference from a negative one. Its endpoints also show that the estimate is compatible with differences larger than the point estimate in either direction. The registry record does not specify the confidence-interval method or whether the analysis adjusted for any other variables.

How should the p-value be read?

The comparison reports an unadjusted p-value of 0.737. In general, a p-value describes how unusual data at least as discrepant as those observed would be under a specified null model and its assumptions. It is not the probability that the null model is true, nor does it quantify the chance that the finding is a false positive. Because the value is unadjusted, it does not account for a multiplicity procedure. The registry record does not report whether other inferential tests were planned or whether any adjustment was intended.

Why can the estimate remain uncertain?

A point estimate is subject to sampling variability: results can differ across samples even when the underlying process is unchanged. The confidence interval expresses this uncertainty in a way that keeps the scale of the estimate visible. The relatively broad interval around the 0.12-point estimate means the data leave considerable uncertainty about the underlying difference. A small p-value is not the only way to assess a result, and a large p-value does not demonstrate that two groups are identical. Precision, the possible range of effects, and the relevance of those effects all matter.

As a general statistical point, standard deviations describe patient-to-patient variability, while standard errors describe uncertainty in estimated quantities such as a mean. The record includes group standard deviations of 1.36 and 1.41 and gives standard errors of 0.248 and 0.257 for the group means. These are different summaries and should not be interchanged. The pooled standard deviation used in the comparison is 1.385. The registry record does not give further details about the calculation method.

The posted comparison is unadjusted. An adjusted analysis can account for prespecified covariates or design features, but the registry record does not report such an analysis for this endpoint. No sponsor-reported inferential analysis is listed among the analyses, so interpretation should remain tied to the posted summaries and comparison rather than assuming an unreported model or adjustment.

Randomization is intended, in general, to support a fair comparison by balancing prognostic factors across groups on average. It does not guarantee exact balance in a particular trial, and the registry record does not provide baseline characteristics with which to assess balance. The record also does not state how randomization was generated or concealed. Consequently, the registered design label supports describing the trial as randomized, but not a detailed evaluation of the allocation process.

Finally, statistical interpretation depends on how outcomes were collected and analyzed. The registry identifies the assessment time and score range, but does not report missing-data methods, exclusions, the analysis population, or a protocol-level analysis plan. Those details could affect how the group summaries should be understood. They should not be inferred from the fact that a mean and standard deviation are posted.

10. Confidence Intervals and Precision

The estimated mean difference is 0.12 points, and the 95% confidence interval runs from -0.581 to 0.821. The interval is the main indicator of precision for the reported comparison: it shows that uncertainty around the estimate extends in both directions and includes zero. Thus, the point estimate is not sufficiently precise to establish a clear direction for the difference.

In general, a confidence interval does not assign probabilities to individual values inside its range. Rather, it is produced by a procedure that, under its assumptions, has a stated long-run coverage property. The registry record does not specify the method used to construct this interval, so the interpretation should not assume details beyond the reported interval and confidence level.

The group means are 6.33 and 6.45, with standard deviations of 1.36 and 1.41. The standard deviations indicate variation in recorded scores within each group, while the confidence interval concerns uncertainty in the between-group difference. The pooled standard deviation is 1.385, and the standardized difference is d = 0.087. These summaries provide different views of the result: scale-based difference, variation within groups, and standardized magnitude.

The interval’s inclusion of both negative and positive values is not proof that the groups are equivalent. A claim of equivalence would require a prespecified range of differences considered acceptably small and an analysis designed to assess that range. No such margin or analysis is reported in the registry record. The record also does not state a threshold for a meaningful change in satisfaction, so the practical interpretation of the interval’s endpoints cannot be anchored to a registry-reported benchmark.

Precision is also shaped by the amount of observed variability and the number of participants contributing usable outcome data. Although the group summaries list 30 patients per group, the registry record does not state whether all randomized patients contributed to the satisfaction analysis or how missing scores were handled. The posted interval should therefore be read as the uncertainty reported for the available comparison, with the underlying analysis details not fully documented.

11. 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 participants per arm, not total participants or total events. They are illustrative calculations based on the observed effect, rather than the trial’s original design assumptions. The calculation uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It considers effects equal to the observed effect and fractions of that effect. The original trial’s sample-size assumptions are not reported in the registry record.

For 100% of the observed effect, the illustration gives 2,092 participants per arm for 80% power and 2,801 participants per arm for 90% power. For 75% of the observed effect, it gives 3,719 participants per arm for 80% power and 4,979 participants per arm for 90% power. For 50% of the observed effect, it gives 8,368 participants per arm for 80% power and 11,202 participants per arm for 90% power.

In plain language, the 80% power column gives the estimated participants per arm under the stated assumptions for a design intended to have an 80% chance of detecting the specified effect if that effect is the true one. The 90% power column expresses the corresponding planning target for a higher chance of detection. These are planning targets, not guarantees that a future study will produce a statistically significant result. A curve based on the same exercise should be read as showing how the required participants per arm change as the effect size to detect changes. Smaller effects need more participants to detect under the same assumptions.

This is not observed power. The figures are planning illustrations generated from the observed effect and the stated assumptions. They do not show the trial’s original planned sample size, and they do not establish what sample size would be appropriate for a future study without a justified effect target and design assumptions.

12. 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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.120; pooled standard deviation σ = 1.385.
2. n = 2 × (1.96 + 0.842)² × 1.385² / 0.120² = 2,091.8, rounded up to 2,092 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
delta <- 0.12                      # observed difference in means
sigma <- 1.385225613393                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2988050)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 2,092 (80% power), 2,801 (90% power)
 75% of observed effect: n per arm = 3,719 (80% power), 4,979 (90% power)
 50% of observed effect: n per arm = 8,368 (80% power), 11,202 (90% power)
power.t.test: 2092.7 
Simulated power at n = 2,092 per arm: 0.801 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and no posted secondary outcomes. Its brief summary mentions other recorded measures, including sedation score, patient and surgeon satisfaction, heart rate, mean arterial blood pressure, oxygen saturation, and side effects. Results for those measures are not reported in the registry record. The listed number of analyses is zero, so no set of posted analyses is available to show how the primary comparison fits within a broader analysis program.

Multiplicity arises when multiple outcomes, comparisons, time points, or analyses are tested. As a general statistical matter, considering many tests can increase the chance of obtaining at least one apparently unusual result under a collection of null hypotheses. Methods such as adjustment or prioritization can address that issue, but the registry record does not report a multiplicity strategy or a detailed statistical analysis plan. The reported p-value is unadjusted, and the record does not establish whether any other tests were conducted.

The registry record does not report how missing satisfaction scores were handled, whether any participants were excluded from the endpoint analysis, or whether the analysis followed an intention-to-treat, per-protocol, or other population definition. It lists 30 patients in each group for the outcome summaries, but does not provide a participant flow or explain whether every randomized patient contributed a score. These omissions limit assessment of missing-data bias and the population represented by the comparison.

Other analysis details are also not reported in the registry record, including interim analyses, covariate adjustment, model diagnostics, and the method used for the confidence interval and p-value. Their absence from the record does not establish that such procedures were not used; it means their use and details cannot be assessed from the registry entry.

14. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The serious and other adverse-event summaries list 30 patients at risk in each named regimen group. The registry records zero patients affected by serious adverse events and zero affected by other adverse events in both Propofol-dexmedetomidine and Propofol-remifentanil groups. No serious adverse-event terms are listed.

These entries describe the event counts recorded in the registry; they should not be interpreted as proof that no adverse events of any kind occurred. The registry record does not provide event definitions, detailed collection procedures, follow-up duration for safety, or a separate account of the specific side effects mentioned in the brief summary. It also does not report deaths in the posted adverse-event summary.

Zero recorded events in these categories are a descriptive finding for the listed groups and at-risk counts. They do not establish that the regimens have identical safety profiles, nor do they rule out uncommon events. The safety summaries should be interpreted alongside the limited size of the trial and the absence of detailed event-level information in the registry record.

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

The posted result describes patient satisfaction one hour after the operation in two randomized groups receiving different conscious-sedation regimens. The group means are 6.33 and 6.45 on the stated scale from 0 to 10. The estimated difference is 0.12 points, with a 95% confidence interval from -0.581 to 0.821 and an unadjusted p-value of 0.737.

Those statistics do not show a clear difference in the recorded average satisfaction scores, but they also do not establish that the regimens produce the same satisfaction. The confidence interval includes zero and leaves uncertainty about the direction and size of the difference. No equivalence margin or clinically important difference is reported, so the result cannot be used to make a registry-grounded claim of equivalence or clinical insignificance.

The result pertains to the specified satisfaction scale at the specified time. It does not answer every question about sedation quality, surgery, recovery, physiological measures, or adverse effects. Although the brief summary lists additional recorded outcomes, no secondary results are posted in the registry record. The serious and other adverse-event summaries report zero affected patients in each group, but the record does not include detailed event descriptions or enough information to treat those zero counts as evidence that risk is absent.

The trial is described as randomized and double-masked, but details of allocation, masking procedures, outcome missingness, and analysis populations are not reported. These limitations constrain evaluation of the result’s robustness and applicability. The posted data are best understood as an imprecise estimate of the difference in the recorded satisfaction score, not as a definitive ranking of the regimens or a claim about outcomes that were not reported.

16. Why This Trial Matters Statistically

This trial provides a useful statistical example of the distinction between a point estimate and the evidence around it. The observed mean difference is 0.12, but the confidence interval extends from -0.581 to 0.821. Focusing only on the point estimate would hide the uncertainty about both the direction and possible size of the difference.

It also illustrates why a non-significant result is not the same as evidence of equivalence. The unadjusted p-value is 0.737, but the registry record does not report a prespecified equivalence margin or an analysis designed to establish equivalence. A conclusion that the groups are the same would go beyond the information recorded.

The endpoint is a patient-reported score on a stated scale and at a specific time after the operation. That specificity makes clear what the posted comparison addresses, while also emphasizing what it does not address. The brief summary names additional clinical and satisfaction measures, yet their results are not posted. A single endpoint result cannot stand in for unreported outcomes.

The record also demonstrates the difference between an observed trial result and a planning illustration. The sample-size figures use the observed effect and stated planning assumptions; they do not describe the original trial design. Reading them as prospective design calculations rather than as a measure of the trial’s success avoids a common interpretive error.

Finally, sparse reporting matters statistically. Without details about missing data, analysis populations, multiplicity, or the statistical plan, readers cannot fully assess the pathway from randomization to the reported comparison. These are not reasons to disregard the recorded result; they define the limits of what can be concluded from the registry record.

17. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry provides limited information for judging how representative the participants were. It identifies epilepsy surgery and awake craniotomy, but detailed eligibility criteria and participant characteristics are not reported in the registry record. The result’s applicability beyond the described trial population therefore cannot be evaluated from the entry alone.

The posted outcome results use the labels Conscious sedation1 and Conscious sedation2, while the intervention descriptions name the propofol-dexmedetomidine and propofol-remifentanil regimens. The registry record does not explicitly map the outcome labels to the named regimens. This makes it important not to assign the posted means to a named drug combination without qualification.

Although the trial is described as randomized and double-masked, details of the random sequence, allocation concealment, who was masked, and how masking was maintained are not reported. Baseline characteristics are also not included in the registry record, limiting assessment of group comparability after randomization.

The registry does not report the endpoint analysis population, missing-score handling, participant flow, or a detailed statistical analysis plan. It also does not report a satisfaction threshold for clinical importance, a multiplicity approach, or detailed safety-event definitions and follow-up. These reporting gaps prevent fuller assessment of possible bias, the interpretation of the score difference, and the completeness of safety ascertainment.

The posted primary result concerns satisfaction at one hour after the operation. Other outcomes mentioned in the brief summary are not posted, and the registry lists no secondary results. The findings should therefore be understood as limited to the reported endpoint and available registry information.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Conscious Sedation for Epilepsy Surgery — NCT02988050.
• Registry record last updated 2020-10-09; status last verified 2020-09.
• Results first posted 2020-10-09.
• 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.

21. Record Summary

NCT02988050 is a completed randomized, double-masked, parallel-group trial sponsored by Menoufia University. The registry lists epilepsy as the condition and describes conscious sedation for awake craniotomy during epilepsy surgery. The listed start date is 2013-08, and the primary completion date is 2016-02.

The registry brief summary describes 60 patients allocated to propofol-dexmedetomidine or propofol-remifentanil intravenous infusion, with 30 patients in each group. The primary outcome is patient satisfaction one hour after the operation, scored from 0 for not satisfied to 10 for totally satisfied.

The posted means are 6.33 and 6.45. The mean difference is 0.12, with a 95% confidence interval from -0.581 to 0.821 and an unadjusted p-value of 0.737. The adverse-event summary records zero affected patients for serious and other events in each named group. No secondary outcome results are posted, and key analysis details are not reported in the registry record.