Pain Control Following Sinus Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pain Control Following Sinus Surgery (NCT03783702), a randomized phase 4 study. The primary outcome is Pain Severity.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group, unmasked trial with a Phase 4 designation. Its official title identifies it as a multi-institutional controlled trial. The registry lists 118 participants enrolled, a start date of 2019-04-04, primary completion on 2020-07-01, and a completed status. The primary endpoint results report 49 participants in the experimental group and 51 in the control group. The registry does not explain why these outcome counts differ from the enrollment figure.

The experimental group was assigned a stepwise regimen beginning with acetaminophen and then ibuprofen if more analgesia was needed. The control group began with acetaminophen and used oxycodone as the second-line medication. The registry describes daily pain assessment using visual analog scales and the Brief Pain Inventory, although the posted primary result is a preoperative pain score. Details such as the randomization procedure, allocation concealment, adherence assessment, and the complete experimental-arm protocol are not reported in the registry record.

The design description frames the study around pain management after endoscopic sinus surgery, including whether non-opioid medication could provide pain control and whether narcotic use could be avoided or limited. Those aims provide context, but they do not change the timing of the primary outcome actually posted: the day before surgery. The registry does not report the trial’s original sample-size justification, planned statistical analysis, or analysis populations.

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

Reasons for not completing this period:

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 Pain Severity, measured over Average pain score will be collected for preoperative visit (the day before surgery).

The primary endpoint is average pain severity recorded at the preoperative visit, specified as the day before surgery. It is measured using a 10-cm visual analog scale, described in the registry as a continuous patient-reported measure on a horizontal 100-mm scale. Its endpoints are no pain, scored 0, and worst imaginable pain, scored 100. The posted summary reports group means and standard deviations.

A visual analog scale is used to represent a person’s own assessment of pain on a continuous scale, rather than restricting responses to a small set of categories. In general, this can retain more gradation in reported severity. The scale is a measure of the construct and time point actually recorded; it does not by itself establish how pain changes over time or how analgesic use affects pain.

The registry’s stated trial purpose concerns pain management after surgery, but the primary endpoint’s recorded timeframe is before surgery. This distinction is essential when interpreting the group summaries: they describe preoperative pain severity, not postoperative pain severity. Why the registry designated this preoperative measure as primary, and whether postoperative pain was intended as another primary endpoint in the original protocol, are not reported in the registry record.

7. Results Posted in the Registry

• Experimental Group: mean 12.40 versus 8.50 on control; difference 3.90 (95% CI -2.81 to 10.61), standardized effect d = 0.23; z-test p = 0.255.

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.

Brief Pain Inventory (BPI) Score

• 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:
  • Experimental Group: mean 1.60 versus 1.00 on control; difference 0.60 (95% CI -0.14 to 1.34), standardized effect d = 0.32; z-test p = 0.112.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Experimental Group and the control. The interval gives the range of effects that remain compatible with the data.

Severity of Epistaxis

• 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:
  • Experimental Group: mean 36.30 versus 38.90 on control; difference -2.60 (95% CI -15.37 to 10.17), standardized effect d = -0.08; z-test p = 0.690.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Experimental Group and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary summaries cover preoperative Brief Pain Inventory scores and severity of epistaxis on postoperative day 1. Their directions are not uniform: the experimental group has a higher preoperative BPI mean and a lower postoperative epistaxis mean than the control group. The reported unadjusted intervals for both comparisons include zero. These summaries therefore do not provide a consistent pattern of clear group separation.

The secondary results do not resolve the main interpretive issue with the primary result. The BPI measure is also preoperative, while epistaxis is a postoperative outcome but is not the primary pain-severity endpoint. These measures address different time points and constructs. They cannot be combined into a single estimate of postoperative pain control or medication use.

Unadjusted secondary comparisons carry less weight as confirmatory evidence when many outcomes are assessed. In general, examining numerous outcomes creates more opportunities for chance findings. A prespecified hierarchy or multiplicity adjustment can help distinguish confirmatory analyses from exploratory ones, but such a plan is not reported in the registry record. The registry lists 25 outcome measures and reports 16 secondary outcomes, while the described secondary analyses do not include reported analysis methods.

The registry’s secondary outcome list includes repeated BPI entries, but the reason for the repeated entries and how they map to the posted outcome results are not reported in the registry record. The registry also reports no analyses in its reported-analysis list. The secondary summaries should therefore be treated as descriptive, unadjusted comparisons rather than as a complete, prespecified test of the study’s aims.

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

• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score
• Brief Pain Inventory (BPI) Score

9. Statistical Interpretation

10. Statistical Methods Explained

The posted continuous outcomes are summarized by group means and standard deviations, with an unadjusted mean difference calculated between the experimental and control groups. The primary comparison is an unadjusted recalculation from the posted summaries. The registry does not report a full statistical analysis plan, so the calculations should not be mistaken for a description of every analysis originally intended.

What does a mean represent?

In general, a mean is the arithmetic average of the recorded measurements in a group. It provides a concise description of the group’s central level on the measurement scale. A mean does not show the full distribution: participants can have scores far from the average, and two groups with similar means can still have different patterns of individual scores. For the primary outcome, the mean is measured in visual analog scale units.

A standard deviation describes how dispersed measurements are around the mean. A larger standard deviation indicates greater spread of individual observations, while a smaller one indicates that observations tend to be closer to the mean. It is not the same as the uncertainty in the estimated mean. The standard error, which is related to the sample size and the variability, describes the sampling uncertainty of an estimated mean.

How should the mean difference be read?

The comparison is defined as the experimental-group mean minus the control-group mean. A positive estimate means the experimental-group average is higher on the outcome scale; a negative estimate means it is lower. The estimate is an unadjusted difference between group summaries, not a participant-level change score. Because the primary measure was recorded before surgery, the direction and size of this difference describe preoperative scores rather than the effect of postoperative analgesic regimens.

Random allocation is intended, in general, to make treatment groups comparable on average, including on characteristics that are not measured. It does not guarantee that every baseline measure will be identical in a particular trial. The registry reports no masking. It does not provide details about allocation concealment, the randomization sequence, or any adjustment for baseline characteristics.

What do the interval and p-value convey?

In general, an interval estimate expresses the uncertainty around an estimated effect by giving a range of values compatible with the data under a specified method. The primary result reports bounds of -2.815 and 10.61, but the confidence level and interval method are not reported in the registry record. The range includes zero, which is the value corresponding to no mean difference. This does not prove that the true difference is zero; it indicates that the posted estimate is not precise enough to exclude values on either side of zero under the interval calculation.

A p-value is, in general, a measure of how unusual data at least as inconsistent 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, nor does it measure the size or practical importance of an effect. The posted primary p-value is unadjusted. The registry record does not report the method used to obtain it or whether it was the prespecified primary test.

Why does outcome timing matter?

Statistical interpretation depends on the endpoint’s definition and timing as well as the calculation. The primary measure is identified as average pain at the preoperative visit, the day before surgery. The study’s stated interest is postoperative analgesia. A result recorded before surgery cannot describe pain experienced after the operation, regardless of whether the group comparison is statistically significant. It may describe baseline pain, but the registry does not report whether a baseline-adjusted postoperative analysis was planned or performed.

The registry lists multiple outcome measures and posts multiple secondary results. When many outcomes are examined, the chance of finding apparently notable results by chance can increase. In general, multiplicity procedures can control that issue by adjusting how evidence is assessed, or by identifying a limited set of prespecified outcomes. The adjustment plan, outcome hierarchy, and any prespecified multiplicity strategy are not reported in the registry record. Secondary p-values described as unadjusted should therefore be treated as exploratory rather than as independent confirmatory evidence.

What can the recalculations establish?

The unadjusted calculations describe differences implied by the posted means, standard deviations, and group counts. They do not recover participant-level information, account for unreported covariates, address missing outcomes, or establish that the calculation matches the original analysis plan. The registry record does not report participant-level data, a detailed analysis population, or a complete statistical methods description. The results are consequently best read as summaries of the posted data, with their limitations made explicit.

11. Confidence Intervals and Precision

The primary mean difference is 3.9 units, with reported interval bounds of -2.815 and 10.61. The interval spans zero, so the posted data do not rule out either a negative or a positive difference. Its width indicates that the estimate is uncertain; readers should consider the range of values rather than focus only on the point estimate.

The confidence level and method for this interval are not reported in the registry record. It should therefore be described as the reported interval, not assumed to be a 95% confidence interval. In general, an interval’s interpretation depends on its construction and assumptions. It is not a range that contains every individual participant’s score, nor is it a direct measure of clinical importance.

The group standard deviations are 20.0 and 13.5, indicating considerable variation in scores relative to the group means. In general, greater variation makes group averages harder to estimate precisely unless accompanied by more information. The primary outcome counts are 49 and 51, while the registry lists enrollment of 118; the reasons for this difference are not reported in the registry record. The effect of any missing or unavailable outcomes on precision cannot be assessed from the posted summaries.

The p-value of 0.255 is unadjusted and should be interpreted alongside the estimated difference and interval. It does not provide the probability that the treatment groups are equal, and it does not measure how important a difference might be. Because the endpoint was measured before surgery, even a more precise estimate would describe a preoperative group comparison rather than postoperative pain control.

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 based on the observed effect, not the trial’s original design calculations. For these continuous outcomes, the figures are participants per arm, not a total number of events. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The registry does not report the original sample-size justification or the trial’s own design assumptions.

For the primary endpoint, planning for 100% of the observed effect gives 299 participants per arm for 80% power and 400 participants per arm for 90% power. Planning for 75% of the observed effect gives 531 participants per arm for 80% power and 710 participants per arm for 90% power. Planning for 50% of the observed effect gives 1,193 participants per arm for 80% power and 1,597 participants per arm for 90% power.

In general, power is the probability that a specified analysis will detect an effect of a chosen size under its assumptions. The 80% and 90% columns describe different target probabilities for detecting the chosen effect, if it is present and the planning assumptions hold. The higher target generally calls for more participants. Smaller effects require more participants to detect because they are harder to distinguish from random variation. These figures are not observed power; they are planning illustrations, not evidence about the probability that the completed trial detected an effect.

The illustration uses the observed effect as its reference, so its results depend on an estimate that is itself uncertain. If the true effect differs from that observed estimate, the planning numbers may not represent the sample size needed for a future study. The registry’s original rationale for enrollment, and whether the trial planned other power targets or assumptions, are not reported in the registry record.

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

Worked calculation for this trial

1. Observed difference Δ = 3.900; pooled standard deviation σ = 16.997.
2. n = 2 × (1.96 + 0.842)² × 16.997² / 3.900² = 298.2, rounded up to 299 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 <- 3.9                      # observed difference in means
sigma <- 16.9971486204154                     # 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(3783702)
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 = 299 (80% power), 400 (90% power)
 75% of observed effect: n per arm = 531 (80% power), 710 (90% power)
 50% of observed effect: n per arm = 1,193 (80% power), 1,597 (90% power)
power.t.test: 299.1 
Simulated power at n = 299 per arm: 0.799 (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.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists 25 outcome measures and reports 16 secondary outcomes. It also includes repeated Brief Pain Inventory entries in its secondary outcome list. The rationale for the number and repetition of listed outcomes, their hierarchy, and the relationship between the registry entries and the posted analyses are not reported in the registry record. This makes it difficult to determine which outcomes were intended to be confirmatory and which were exploratory.

Multiplicity matters because, in general, the more statistical comparisons are made, the greater the opportunity for apparently notable findings to arise by chance. Researchers may address this through an adjustment procedure, a prespecified outcome hierarchy, or another strategy. The trial’s multiplicity plan and any adjustment to secondary p-values are not reported in the registry record. The posted secondary comparisons are unadjusted recalculations and should not be treated as independent confirmation of the primary result.

The registry does not report how missing outcome data were handled, whether any imputation was used, or how participants with incomplete measurements were included in analyses. It lists enrollment of 118, while the primary outcome summaries report 49 and 51 participants in the two groups. Reasons for these counts, including whether they reflect missing data, exclusions, or another analysis population, are not reported in the registry record. The effect of missing information on the results cannot be assessed from group summaries alone.

The analysis population is not reported in the registry record. It is therefore unclear whether the posted summaries include all randomized participants, only those with available outcome measurements, or another defined group. The registry also does not report an intention-to-treat analysis, a per-protocol analysis, interim analyses, or the full statistical analysis plan. No assumptions about these methods should be inferred from the reported group means and p-values.

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 0% reporting threshold.

The registry reports zero serious adverse events, zero other adverse events, and zero deaths in both groups. The reported numbers at risk are 49 in the experimental group and 51 in the control group. No serious adverse event terms are listed. These are the safety figures recorded in the registry; they do not establish that no events occurred outside the reported collection and reporting process.

In general, adverse-event counts are best interpreted alongside how events were defined, the period over which they were collected, how they were solicited, and the population included in safety monitoring. Those details are not reported in the registry record. The registry also does not describe the severity criteria used for non-serious events or give event-level details. With zero events recorded, the posted figures do not permit a comparison of event types or timing between groups.

The safety counts should be read separately from the pain scores and should not be used to infer the effectiveness of either analgesic regimen. They describe reported event totals in the registry record, not a complete account of every possible safety outcome.

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

The posted statistics establish that the registry reports a preoperative pain-severity mean of 12.4 in the experimental group and 8.5 in the control group, with an unadjusted mean difference of 3.9 units. The reported interval ranges from -2.815 to 10.61, and the unadjusted p-value is 0.255. The interval includes zero and allows for differences in either direction; the summary does not establish a clear between-group difference.

What the result does not establish is equally important. The endpoint was measured at the preoperative visit, the day before surgery. It is not a measure of postoperative pain, nor does it directly measure whether opioid use was avoided or limited after surgery. The trial’s stated purpose concerns post-surgical analgesia, but the timing of this primary outcome does not directly answer that purpose.

The registry does not report the original statistical analysis plan, the confidence level for the interval, missing-data methods, or the analysis population. The posted result is an unadjusted recalculation from group summaries. Those gaps limit how fully the result can be connected to the trial’s planned analyses and the enrolled population.

The group summaries are not evidence that one regimen should be selected for an individual patient, and they do not establish a treatment recommendation. They describe a particular recorded outcome at a particular time in a randomized study. Interpretation of postoperative pain and medication use would require the relevant postoperative outcomes and analysis details. The secondary summaries provide some postoperative information, but they are unadjusted and do not replace a clearly reported analysis of postoperative pain or opioid consumption.

17. Why This Trial Matters Statistically

This trial raises a statistically important distinction between a study’s clinical objective and the endpoint that is actually reported. The stated objective concerns pain management after endoscopic sinus surgery, while the primary pain-severity measure is collected before surgery. Statistical calculations cannot overcome that mismatch: a precisely estimated preoperative comparison would still not be a direct estimate of postoperative pain control.

The example also illustrates why a point estimate should be read with its uncertainty. The primary mean difference is accompanied by an interval that spans zero and a non-significant unadjusted p-value. Neither should be interpreted as proof of no difference. The interval communicates that several possible group differences remain compatible with the reported summary, while the p-value alone does not describe effect size, clinical importance, or the probability that a hypothesis is true.

Many outcome measures create further interpretive challenges. Without a reported hierarchy or multiplicity plan, secondary comparisons are difficult to distinguish as confirmatory or exploratory. The registry’s lack of reporting on missing-data methods and analysis populations also limits assessment of how well the posted summaries represent the randomized groups.

Finally, planning calculations are not a substitute for the original design rationale. Illustrations based on the observed effect can show how sample requirements change as target effects and power targets change, but they do not reveal what assumptions informed the trial’s enrollment. Clear endpoint timing, a prespecified analysis plan, and transparent reporting of analysis populations are all essential for linking trial statistics to the question the study set out to address.

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.

A central limitation is the mismatch between the trial’s stated postoperative pain-management aim and the primary endpoint’s preoperative timing. The primary outcome is recorded the day before surgery, so it does not directly measure the postoperative pain experience under either regimen. This limits the relevance of the primary comparison to the stated post-surgical question.

The registry’s experimental-arm description is truncated while describing oxycodone. Although the general summary describes acetaminophen and ibuprofen as the non-opioid regimen, full protocol details for the experimental arm are not reported in the registry record. Details about treatment adherence, crossovers, and the timing of medication initiation are also not reported.

The registry lists 118 enrolled participants, but the primary outcome summaries report 49 and 51 participants by group. The reasons for this difference are not reported in the registry record. Missing-data handling, analysis populations, and whether all randomized participants were included are also not reported, limiting assessment of potential bias and generalizability.

The record does not report the trial’s original sample-size justification, complete statistical analysis plan, confidence level for the reported interval, or multiplicity strategy. It does not give details about randomization procedures, allocation concealment, or the locations and number of participating institutions. The unmasked design may also matter for patient-reported outcomes, but the registry does not describe measures taken to address that concern. These limitations constrain interpretation of the posted estimates without establishing that any particular bias occurred.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Pain Control Following Sinus Surgery — NCT03783702.
• Registry record last updated 2021-09-01; status last verified 2021-08.
• Results first posted 2021-09-01.
• 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.

22. Record Summary

The registry describes a completed, randomized, unmasked, parallel-group Phase 4 trial of stepwise analgesic regimens for patients undergoing endoscopic sinus surgery. Enrollment is listed as 118. The experimental regimen began with acetaminophen followed by ibuprofen if needed; the control regimen began with acetaminophen followed by oxycodone if needed.

The primary endpoint is average pain severity at the preoperative visit, the day before surgery. The posted unadjusted mean difference is 3.9 units, with interval bounds from -2.815 to 10.61 and an unadjusted p-value of 0.255. The endpoint timing means this is a preoperative comparison, not a direct result for postoperative pain control. The registry does not report the original sample-size rationale, detailed analysis plan, missing-data methods, or analysis population.