Oral Caffeine Use for Pain Management in AIS Patients After Spinal Fusion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Oral Caffeine Use for Pain Management in AIS Patients After Spinal Fusion (NCT04950660), a randomized phase 4 study. The primary outcome is Total Post Operative Oral Morphine Milligram Equivalents (MME)/Kilogram (Kg) for Hospital Stay.

2. Clinical Question

The question is clinically framed around opioid use after surgery, but the statistical contrast concerns group means for a continuous measure. The reported mean was 0.83 MME/Kg in the caffeine arm and 0.92 MME/Kg in the placebo arm. The unadjusted mean difference, expressed as caffeine minus placebo, was -0.09 MME/Kg. Its interval extends from -0.296 to 0.116, so the posted estimate is compatible with values on either side of no difference.

The registry also lists pain ratings, heart rate, and systolic blood pressure as secondary outcomes. These are related measures of the postoperative hospital course, but they do not replace the primary opioid-exposure endpoint. The results describe the participants included in the posted outcome groups; they do not establish what would happen in every patient or setting.

3. Trial Design

The registry record describes a prospective, randomized, controlled trial with a parallel-group model and triple masking. It lists the study as Phase 4 and completed. The sponsor is Children's Mercy Hospital Kansas City. The record gives a start date of 2019-12-11 and a primary completion date of 2024-01-20. These design and status details describe the trial as registered; they do not by themselves establish how every element was implemented.

Participants were assigned to caffeine or placebo, with both treatments intended as additions to standard pain control. The caffeine arm description specifies a 100 mg dose twice daily, while the placebo was described as compounded to look similar and taken twice daily. The record does not specify in the posted results what standard pain-control treatments were used, how allocation was generated or concealed, or which specific parties were masked. Those details are not reported in the registry record.

There is a difference between the registry’s overall enrollment figure, the planned arm descriptions, and the counts accompanying the posted outcomes. Enrollment is listed as 61. The arm descriptions each state n = 34, while the primary outcome lists 24 participants in the caffeine group and 27 in the placebo group. The posted secondary outcomes use those same group counts. The record does not explain the relationship among these counts, so the reasons for the difference are not reported in the registry record.

The primary measure covers the hospital stay, up to 7 days. The secondary measures are mean daily verbal analog scale ratings, average heart rate during the hospital stay, and average systolic blood pressure during the hospital stay, each with the same stated timeframe. Although the trial is marked completed, the registry record lists no reported analyses for these outcomes. The available numeric results are group summaries and unadjusted recalculated comparisons, not a detailed account of a prespecified analysis plan or the trial team’s full analysis.

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 Total Post Operative Oral Morphine Milligram Equivalents (MME)/Kilogram (Kg) for Hospital Stay, measured over For hospital stay up to 7 days.

The primary endpoint is total postoperative oral morphine milligram equivalents per kilogram for the hospital stay, with a stated timeframe of up to 7 days. Morphine milligram equivalents express opioid amounts on a common scale; expressing the total per kilogram relates the recorded amount to body weight. The endpoint is continuous, and the registry presents a mean and standard deviation for each group.

This measure is relevant to a trial asking about postoperative opioid use because it summarizes the amount of oral opioid exposure recorded over the hospital stay. It is not identical to the frequency of opioid demands. A total amount can reflect how much medication was taken or recorded, whereas frequency concerns the number of requests. The registry lists the objective as reducing demand frequency, but the posted primary outcome does not report a request count as its primary measure. The number of requests for diazepam appears in the study summary as a comparison of interest, not among the posted numeric outcomes.

For the primary endpoint, the caffeine group mean was 0.83 MME/Kg with a standard deviation of 0.41, based on 24 participants. The placebo group mean was 0.92 MME/Kg with a standard deviation of 0.33, based on 27 participants. The estimated mean difference was -0.09 MME/Kg, with an interval from -0.296 to 0.116. These summaries describe the recorded outcome among the participants in the posted groups. The registry does not report the distribution of individual values, the handling of missing observations, or additional details of endpoint measurement.

7. Results Posted in the Registry

• Caffeine Arm: mean 0.83 versus 0.92 on control; difference -0.09 (95% CI -0.30 to 0.12), standardized effect d = -0.24; z-test p = 0.392.

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.

Mean Daily Verbal Analog Scale (VAS)

• 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:
  • Caffeine Arm: mean 3.33 versus 3.51 on control; difference -0.18 (95% CI -1.04 to 0.68), standardized effect d = -0.12; z-test p = 0.683.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Caffeine Arm and the control. The interval gives the range of effects that remain compatible with the data.

Average Heart Rate During Hospital Stay

• 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:
  • Caffeine Arm: mean 78.80 versus 83.80 on control; difference -5.00 (95% CI -11.23 to 1.23), standardized effect d = -0.44; z-test p = 0.116.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Caffeine Arm and the control. The interval gives the range of effects that remain compatible with the data.

Average Systolic Blood Pressure During Hospital Stay

• 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:
  • Caffeine Arm: mean 98.30 versus 101.40 on control; difference -3.10 (95% CI -6.70 to 0.50), standardized effect d = -0.47; z-test p = 0.091.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Caffeine Arm and the control. The interval gives the range of effects that remain compatible with the data.

Across the three secondary outcomes, the caffeine-group means are lower than the corresponding placebo-group means. The estimates concern pain ratings, average heart rate, and average systolic blood pressure during the hospital stay. Each is an unadjusted comparison, and the posted intervals for these outcomes include zero. The pattern is directionally similar across measures, but it does not remove the uncertainty in any individual comparison.

These outcomes provide context for the primary opioid-exposure result because they describe other aspects of the postoperative hospital course. They are not interchangeable with opioid exposure, and none directly supplies the unreported frequency of opioid demands. Their direction does not establish that the primary endpoint’s underlying effect is nonzero, or that changes in one measure explain changes in another. The registry does not report analyses of relationships among these outcomes.

Secondary results generally carry less weight for confirmatory conclusions when many outcomes are examined without a reported testing hierarchy or multiplicity adjustment. Repeated testing can increase the chance of finding an apparently notable result by chance. That general concern applies even when results point in a consistent direction; direction alone does not account for uncertainty or the number of comparisons. The registry record does not report a multiplicity adjustment, a prespecified hierarchy, or a detailed analysis plan for these outcomes.

The posted secondary findings are therefore best treated as descriptive comparisons that may inform future questions, rather than as independent confirmation of the primary result. The record lists three secondary numeric outcomes and no reported analyses. It does not provide information about whether additional unposted outcomes were analyzed, how missing observations were handled, or whether these measures were selected before data were examined.

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

• Mean Daily Verbal Analog Scale (VAS)
• Average Heart Rate During Hospital Stay
• Average Systolic Blood Pressure During Hospital Stay

9. Statistical Interpretation

10. Statistical Methods Explained

The primary result compares a continuous outcome between two parallel randomized groups. The outcome is total postoperative oral MME per kilogram for the hospital stay, reported as a mean and standard deviation. A mean describes the average value in a group; a standard deviation describes how dispersed individual observations are around that group average. The standard deviation is not the uncertainty interval for the mean difference.

What does the mean difference represent?

The contrast is calculated as the caffeine-arm mean minus the placebo-arm mean. The group means are 0.83 and 0.92 MME/Kg, respectively, and the estimated contrast is -0.09 MME/Kg. A negative value indicates that the reported caffeine-group mean is lower on this outcome scale. It does not, on its own, indicate whether the difference is statistically distinguishable from zero, whether it is clinically important, or whether it represents a causal effect in a broader population.

The comparison uses independent groups, rather than paired measurements from the same participants. The posted recalculation uses the group sample sizes and standard deviations to estimate an unadjusted difference and its uncertainty. It does not adjust for other participant characteristics or outcomes. The registry does not report the trial team’s model specification, covariate adjustment, or analysis population, so those details should not be inferred from the summary comparison.

What does an interval add?

An interval around an estimate represents a range of values that are reasonably compatible with the data under the method’s assumptions. Wider intervals indicate less precision; narrower intervals indicate greater precision. The primary difference interval runs from -0.296 to 0.116 MME/Kg. Because zero lies within it, the data do not rule out no mean difference under the interval method. The same interval also allows differences in either direction. It is not a range containing every individual participant’s outcome, and it does not mean that every value inside it is equally likely.

The registry does not state the confidence level associated with the posted interval in the information available for these results. It is therefore appropriate to discuss the interval’s endpoints and whether it includes zero, but not to attach an unreported confidence level to it. A p-value answers a different question: under a specified null model and its assumptions, it describes how unusual a test statistic at least as extreme as the observed one would be. It is not the probability that the null hypothesis is true, nor a measure of the size or clinical importance of an effect.

How should the unadjusted p-values be read?

The primary unadjusted p-value is 0.392. It does not provide evidence against a zero mean difference at commonly used thresholds, but that should not be interpreted as proof that the groups have identical outcomes. The registry does not report whether the trial used a different prespecified test, whether an adjusted analysis was conducted, or whether the posted result reflects the primary analysis plan. No reported analyses are listed for the primary or secondary outcomes.

Unadjusted means that the comparison is not described as accounting for other variables or for the fact that multiple endpoints were examined. That makes the result straightforward to read as a two-group summary contrast, while limiting what can be said about adjustment and confirmatory inference. The registry does not report a multiplicity procedure, such as controlling the chance of false positive findings across several tests.

Why do sample-size illustrations depend on the assumed effect?

The planning illustrations use the observed effect as a starting point and consider fractions of that effect. General statistical principle: if the true difference to be detected is smaller while other planning assumptions stay fixed, more participants are generally needed to distinguish it from random variation. The displayed planning numbers are not observed trial outcomes and are not evidence about the probability that this completed trial detected an effect. They are illustrations based on specified assumptions, not a report of the trial’s original sample-size justification.

The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation, with the effect to detect set to the stated fraction of the observed effect. The registry record does not report the original design assumptions, the sample-size justification used when the trial was planned, or interim analyses. The planning illustrations should therefore be kept separate from claims about the trial’s design or conduct.

All these methods rely on data and assumptions. General statistical principle: an estimate can be sensitive to how outcomes are measured, which participants are included, and how missing data are handled. The record does not describe the distribution of individual outcomes or missing-data procedures. The group means and standard deviations are useful summaries, but they cannot answer every question about the data’s shape or the analysis process.

11. Confidence Intervals and Precision

The primary mean difference is -0.09 MME/Kg, with an interval from -0.296 to 0.116. The interval crosses zero: its negative endpoint is compatible with a lower mean in the caffeine group, while its positive endpoint is compatible with a higher mean. The estimate’s direction is therefore not settled by the interval. The unadjusted p-value is 0.392, consistent with the interval’s failure to distinguish the observed difference from no difference.

Precision concerns how tightly the data locate an estimate, not whether the estimate is important. A relatively wide interval allows a range of possible contrasts, so the point estimate should not be treated as an exact measure of the underlying difference. The interval does not show the range of individual MME/Kg values, and it does not establish the probability that the true difference lies within its endpoints. The confidence level for the interval is not reported in the registry record.

The primary outcome groups include 24 and 27 participants. The secondary outcome intervals also include zero, with the posted ranges extending to both sides of no difference. Their unadjusted p-values do not resolve the uncertainty. None of the intervals should be read as demonstrating equivalence: an equivalence conclusion requires a prespecified equivalence margin and a suitable analysis, neither of which is reported in the registry record.

More precise estimates would generally require more informative data, but precision is not determined by sample count alone. Variability, outcome measurement, and analysis choices also matter. The registry record does not provide individual-level observations, missingness details, or an analysis plan that would permit a fuller assessment of those influences.

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 participants per arm, not total events. They illustrate the sample size associated with detecting the stated fraction of the observed effect under the listed assumptions. The columns for 80% power and 90% power describe planning targets: in general terms, power is the chance that a study will identify an effect at the chosen significance level if the assumed effect and other planning assumptions hold. The 90% target calls for a higher chance of detecting that assumed effect than the 80% target, and therefore has larger participant requirements in these illustrations.

The stated 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. For example, the planning rows distinguish using 100% of the observed effect from using 75% or 50% of it. Smaller assumed effects need more participants because they are harder to distinguish from random variation. These are planning illustrations computed from the observed effect, not the trial’s original design assumptions; the original design assumptions are not reported in the registry record.

Read the figures as conditional planning estimates, not as a description of the participants who enrolled or completed outcome measurement. The primary outcome groups contain 24 and 27 participants, while the planning figures refer to much larger group sizes under their stated scenarios. The planning calculations are not observed power: observed power is not a useful substitute for interpreting the estimated effect and its uncertainty after results are available.

The sample-size illustrations do not establish that the trial was designed around the observed effect, nor do they explain the difference among the enrollment and arm counts recorded in the registry. They are useful for understanding how assumed effect size and power targets change planning requirements, not for reconstructing the trial’s original rationale.

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 = -0.090; pooled standard deviation σ = 0.370.
2. n = 2 × (1.96 + 0.842)² × 0.370² / -0.090² = 264.9, rounded up to 265 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 <- -0.0900000000000001                      # observed difference in means
sigma <- 0.369713071316177                     # 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(4950660)
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 = 265 (80% power), 355 (90% power)
 75% of observed effect: n per arm = 471 (80% power), 631 (90% power)
 50% of observed effect: n per arm = 1,060 (80% power), 1,419 (90% power)
power.t.test: 265.9 
Simulated power at n = 265 per arm: 0.806 (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 one primary outcome and three secondary outcomes with numeric results. Each comparison has an unadjusted p-value, and no reported analyses are listed. The record does not state whether a multiplicity adjustment was planned or applied, whether the primary outcome was tested under a prespecified hierarchy, or whether secondary analyses were intended to be confirmatory or exploratory. Without that context, the p-values should be read as unadjusted results rather than as family-wise or otherwise multiplicity-controlled evidence.

Multiplicity matters because examining multiple outcomes creates more opportunities for a chance finding. General statistical principle: when several hypotheses are tested, the interpretation of each individual p-value may need to account for the set of tests, especially when claims are based on the most favorable result. This does not mean that every result is false; it means the strength of evidence depends partly on the testing plan. That plan is not reported in the registry record.

The registry does not report missing-data counts, reasons for missingness, imputation methods, or sensitivity analyses. The primary and secondary posted outcomes each have 24 participants in the caffeine group and 27 in the placebo group, but the record does not explain whether these counts reflect all randomized participants with available outcomes, a restricted analysis population, or another process. The registry lists 61 as enrollment and n = 34 in each arm description, which does not match the posted outcome counts. It does not provide a participant flow account that reconciles them.

Analysis-population definitions are also not reported. The registry does not say whether results follow an intention-to-treat approach, a per-protocol approach, or another rule for assigning participants to analyses. It does not describe exclusions, treatment adherence, or crossovers. These omissions limit assessment of how closely the posted comparisons preserve the randomized groups and how missing outcomes may affect the estimates.

The original sample-size justification, interim analyses, and detailed statistical analysis plan are not reported in the registry record. The available planning illustrations use the observed effect and stated assumptions, but they cannot substitute for the original design rationale or establish what decisions were planned before results were available.

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 posted adverse-event figures list zero serious adverse events and zero other adverse events in both groups. They also list zero deaths in both groups. The figures are reported for 24 participants at risk in the caffeine group and 27 in the placebo group. No serious adverse-event terms are listed.

These counts describe what is recorded for the posted groups; they do not show that an event is impossible or establish that the treatments have identical safety profiles. A zero count in a limited group still leaves uncertainty about less common events and about events not captured or reported. The registry does not provide further details about adverse-event definitions, collection procedures, severity grading, follow-up beyond the stated hospital period, or the handling of missing safety information. The different enrollment and arm-description counts are not reconciled with the safety-group counts in the registry record.

Safety figures should therefore be read as recorded event counts in the reported groups, not as a guarantee about risks for other patients or settings.

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

The results describe group averages among the participants with posted outcomes. For the primary outcome, the estimated caffeine-minus-placebo mean difference is -0.09 MME/Kg, and the interval ranges from -0.296 to 0.116. The interval includes zero, and the unadjusted p-value is 0.392. The data therefore leave uncertainty about the direction and size of the difference; they do not establish that the groups are identical or that one group has a reliably lower average.

The result also does not directly answer the stated question about frequency of opioid demand. The primary posted measure is total oral morphine milligram equivalents per kilogram over the hospital stay. It concerns amount of exposure, not the number of requests. The registry summary mentions opioid demand and other comparisons, but a numeric request-frequency outcome is not among the posted results.

Nor do the results show that caffeine caused the observed group differences in the broader population. Randomization is an important design feature, but interpretation also depends on implementation, follow-up, analysis populations, missing data, and prespecified methods. The registry record does not report enough detail on those topics to evaluate them fully. The posted contrasts are unadjusted recalculations from summary statistics.

The secondary outcomes point in the same direction in terms of their group means, but their intervals include zero and they are unadjusted. The absence of reported multiplicity procedures further limits confirmatory interpretation. These findings should not be treated as proof of benefit, proof of no effect, equivalence, or a substitute for the missing demand-frequency result.

For readers, the most defensible conclusion is limited to the measured outcomes and reported groups: the caffeine-group primary mean was lower than the placebo-group mean, but uncertainty remains substantial enough to include no difference and differences in either direction. The registry record does not establish the clinical importance of the point estimate, and it does not report a threshold for a meaningful difference.

17. Why This Trial Matters Statistically

This trial illustrates why the endpoint definition matters as much as the study question. The registry’s objective refers to reducing the frequency of opioid demand, while the posted primary outcome is total oral morphine milligram equivalents per kilogram. Both relate to postoperative opioid use, but amount and request frequency are distinct quantities. A result for one cannot automatically stand in for the other.

It also illustrates the importance of reading an estimate together with its uncertainty. A group difference has a direction and a magnitude, but the interval communicates how much ambiguity remains. In this trial, the primary interval crosses zero and the unadjusted p-value does not resolve that ambiguity. Reporting the point estimate alone would give an incomplete account; treating the p-value alone as a verdict would also be misleading.

The record’s group counts raise a separate interpretive issue. Overall enrollment is listed as 61, arm descriptions say n = 34 for each group, and posted outcome groups contain 24 and 27 participants. Those figures are not reconciled. Statistical interpretation depends on knowing which randomized participants contributed data and how exclusions or missing outcomes were handled. Without a participant flow or analysis-population description, readers cannot fully trace that path.

Finally, the secondary measures show why several outcomes require an explicit testing plan. Similar directions across outcomes may be descriptively interesting, but multiple unadjusted tests do not independently confirm a primary finding. The registry does not report a multiplicity strategy or the original sample-size rationale. These features make transparent reporting of outcomes, analysis populations, missingness, and prespecified methods important for evaluating the evidence.

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 posted outcome counts do not match the other participant counts in the registry record. Enrollment is listed as 61, each arm description says n = 34, and the primary and secondary outcomes report 24 participants in the caffeine group and 27 in the placebo group. The record does not explain this difference. Without a participant flow account, it is not possible to determine from these results how many randomized participants were excluded from each analysis or why.

The primary endpoint is total opioid exposure per kilogram, whereas the stated objective concerns frequency of opioid demand. This limits direct interpretation of the posted primary result as an answer about requests. The registry summary mentions a comparison of opioid demand, but no numeric request-frequency result is posted among the outcomes described.

The record does not report detailed eligibility criteria, demographic descriptions of the analyzed groups, the specific standard pain-control regimen, or operational details for measuring the endpoints. It also does not report how missing observations were handled, the analysis population, treatment adherence, or crossovers. These omissions limit assessment of the comparability and completeness of the analyzed groups.

The comparisons are unadjusted recalculations from summary statistics, and the registry lists no reported analyses. The original analysis plan, sample-size justification, interim analyses, and multiplicity procedures are not reported. As a result, the posted results do not establish whether these calculations match the trial team’s planned primary analysis. The interval confidence level is also not reported in the information available for these results.

These limitations do not erase the posted descriptive findings, but they constrain how broadly or conclusively they can be interpreted.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Oral Caffeine Use for Pain Management in AIS Patients After Spinal Fusion — NCT04950660.
• Registry record last updated 2025-02-21; status last verified 2025-01.
• Results first posted 2025-02-21.
• 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

NCT04950660 is a completed Phase 4 randomized parallel-group trial sponsored by Children's Mercy Hospital Kansas City. It studied oral caffeine as an adjunct to standard pain control in children with adolescent idiopathic scoliosis after spinal fusion, using placebo as the comparator. The registry describes the trial as prospective and triple masked.

The primary outcome is total postoperative oral MME/Kg during the hospital stay, up to 7 days. The posted means are 0.83 in the caffeine group and 0.92 in the placebo group; the unadjusted mean difference is -0.09, with an interval from -0.296 to 0.116 and an unadjusted p-value of 0.392. Three secondary outcomes are also posted, with unadjusted comparisons.

The primary interval includes zero, and the record does not post a numeric outcome for frequency of opioid demands. The record also does not reconcile enrollment of 61, arm descriptions of n = 34 per group, and outcome counts of 24 and 27. Details of missing-data handling, analysis populations, multiplicity, and the original sample-size justification are not reported in the registry record.