Safety and Efficacy of Patient Controlled Analgesia in the Emergency Department: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of Patient Controlled Analgesia in the Emergency Department (NCT00910208), a randomized na study. The primary outcome is Short Term Efficacy: Change in Pain Intensity as Assessed by Patient Self Report on Numerical Rating Scale.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. It was listed as completed. The recorded enrollment was 211. The trial was sponsored by Albert Einstein College of Medicine, and the registry lists its start as 2009-04 and primary completion as 2010-06. Phase is listed as NA.

Participants were assigned to one of the stated regimens: PCA with a 1 mg demand dose, PCA with a 1.5 mg demand dose, or a non-PCA comparison regimen. Each regimen included a 0.1 mg/kg morphine loading dose. The PCA arms specified demand dosing every 6 minutes, whereas the comparison arm allowed additional analgesia as needed. The registry's brief summary frames the study aims as assessing PCA efficacy and safety in the emergency-department setting and comparing the two PCA dosing regimens.

For the primary endpoint, the posted group summaries include 67 participants in the PCA 1 mg demand-dose arm, 70 in the PCA 1.5 mg demand-dose arm, and 69 in the non-PCA comparison group. The record does not explain how the enrollment figure relates to the numbers contributing to this endpoint, or whether these are analysis-population counts. The randomization method, allocation concealment, and details of treatment delivery are not reported in the registry record. The record also does not report the rationale for the enrollment target or whether enrollment was adjusted during the trial.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Short Term Efficacy: Change in Pain Intensity as Assessed by Patient Self Report on Numerical Rating Scale, measured over Baseline and 30 minutes post treatment.

The primary endpoint is the change in pain intensity between baseline and 30 minutes post treatment, measured using a patient-reported Numerical Rating Scale. The scale runs from 0, meaning no pain, to 10, meaning worst imaginable pain; higher scores indicate worse pain. Change is defined as the baseline score minus the 30-minute score. Under this direction of subtraction, a positive change indicates a decrease in reported pain, while a negative change indicates an increase.

The registry reports the mean change for each group and a 95% confidence interval. A mean is a measure of the group's average change; it does not describe every participant's response or the spread of individual responses. The confidence interval communicates uncertainty around the estimated group mean. Its width is relevant to how precisely that mean is estimated, while the individual scores may vary more widely.

A short-term, patient-reported measure can describe change over the specified interval and capture the participant's own assessment. It does not, by itself, describe longer-term pain, other outcomes, or the full balance of benefits and harms. The registry record does not report further details about how the NRS was administered or how missing assessments were handled.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is a numerical change score, and the registry reports a mean for each arm. The analysis named in the registry is ANOVA, a general method for comparing group means. An overall ANOVA addresses whether the observed group means are compatible with a common mean under the model used. It does not, on its own, identify which pairs differ or quantify a particular pairwise difference. Pairwise estimates would need their own contrast estimates and uncertainty intervals.

What does the mean describe?

A group mean combines participants' change scores into one measure of average change. This is useful for a high-level comparison, but it can conceal variation among individual responses. The registry lists no standard deviations or other measure of participant-level dispersion for the endpoint; it reports confidence intervals around the means. A confidence interval is an estimate of uncertainty about a parameter, such as a group mean. It is not a range containing a specified proportion of individual participants' outcomes.

The intervals are 95% confidence intervals. In general, the confidence level describes the long-run behavior of the method used to construct intervals under its assumptions; it does not mean that 95% of participants had changes within the interval. The intervals reported for the three group means are 3.0 to 4.6, 3.3 to 4.6, and 2.9 to 4.4, respectively. Since these intervals are for separate means, visual overlap or non-overlap is not a substitute for a direct statistical comparison between groups.

How should the ANOVA result be read?

The registry reports an ANOVA p-value of 0.82 for the three-group analysis. A p-value summarizes how incompatible the observed data are with the null hypothesis used by that test, assuming the model and its assumptions. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of a group difference. The reported value does not demonstrate equivalence; establishing equivalence would require a defined equivalence margin and an analysis designed to assess it. Such a margin is not reported in the registry record.

ANOVA relies on assumptions about the outcome and the errors in the model. General considerations include independence of observations, appropriate handling of the outcome distribution, and the behavior of variability across groups. The registry record does not state how those assumptions were checked or whether the analysis used any adjustment. The change score is based on two measurements for each participant, but the record does not describe a repeated-measures model or an adjustment for baseline values.

What can recalculation add?

Simple recalculation from posted summaries can sometimes estimate an unadjusted difference between two group means. That is distinct from the sponsor's own analysis and does not reproduce an adjusted or otherwise specified model. For this continuous endpoint, values for a two-arm comparison are not reported or estimable in the registry record. There is therefore no posted recalculated pairwise estimate to interpret alongside the overall ANOVA. No discrepancy between a sponsor analysis and a recalculation is identified in the registry record.

The registry gives the arm-level group sizes and confidence intervals, but the underlying individual observations are not reported. Summary data cannot reveal all features of the score distribution, identify influential observations, or support a check of assumptions that requires participant-level data. The record also does not report whether the confidence intervals were based on a particular variance estimator or whether the ANOVA included covariates.

How do planning illustrations differ from trial evidence?

Any sample-size planning illustration based on an observed effect is a hypothetical planning exercise, not a result about the trial's observed power. The stated assumptions for such illustrations are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Those assumptions do not establish that the original trial used them. The registry record does not report the trial's sample-size justification or its original planning assumptions. Planning values, where presented, should be understood as prospective illustrations under stated assumptions, not as observed outcomes or proof that the trial was adequately powered.

The registry also lists six outcome measures and six analyses, but the record does not provide enough detail to determine how the full analysis program was specified. No assumption should be made about interim analyses, a prespecified statistical analysis plan, or the use of covariate adjustment. In general, interpretation depends not only on the test name but also on the model, population, outcome handling, and multiplicity strategy. Those details are not reported in the registry record.

10. Analyses Reported by the Sponsor

The registry reports the sponsor's primary analysis as an ANOVA across the three groups, with a p-value of 0.82. This is the available inferential result for the primary endpoint. The arm-level means and confidence intervals add descriptive context, but they are not a substitute for the ANOVA or for direct estimates of pairwise differences.

Values for a two-arm continuous-outcome comparison are not reported or estimable in the registry record. Thus, there is no posted pairwise recalculation to compare with the sponsor's overall test. No discrepancy is identified between the sponsor analysis and a recalculation. The reported sponsor analysis should therefore be read as the registry's inferential result, while recognizing that it addresses the overall group comparison rather than establishing equivalence or quantifying each pairwise contrast.

The record does not give the full model specification, analysis population, or further detail about adjustments. It is not possible from the registry record to determine whether the reported ANOVA included covariates or how missing scores were treated. The result is best interpreted within the scope of the stated endpoint and the analysis actually reported, without inferring unreported methods.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and six analyses. The primary outcome considered in these results is the short-term change in NRS pain intensity. Need for supplementary analgesia is listed as a secondary outcome. The other outcome details and their corresponding results are not reported in the registry record in the registry record relevant to this account.

When a study examines multiple outcomes or makes multiple comparisons, the chance of at least one apparently notable result can increase. General methods for addressing this include prespecifying a hierarchy of outcomes or adjusting the interpretation of multiple tests. The registry record does not report whether any multiplicity strategy was planned or used. The overall ANOVA across the three groups is the reported primary test; separate pairwise tests and any adjustment for them are not reported.

The record does not state how many participants had an available primary endpoint for analysis beyond the group counts accompanying the outcome summaries. It does not identify an intention-to-treat, per-protocol, or other analysis population. The relationship between enrollment and the endpoint group counts is not explained in the registry record, so the counts should not be treated as evidence of a particular population definition.

Missing data handling is also not reported. The registry does not say how absent baseline or 30-minute scores were treated, whether any imputation was used, or whether missingness differed across groups. General statistical interpretation can be affected by both the amount and pattern of missing data, particularly when the analyzed observations may not represent all randomized participants. Without the registry's analysis-population and missing-data details, the extent of that issue cannot be assessed from the posted information.

Similarly, the record does not report interim analyses, stopping rules, or a full statistical analysis plan. These omissions do not establish that such methods were or were not used; they indicate that they cannot be evaluated from the registry record.

12. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: transient decrease in blood pressure (1.4%), transient oxygen desaturation as measured by pulse oximetry (1.4%).

The registry lists serious adverse events affecting 0 participants in the PCA 1 mg demand-dose group, 1 participant in the PCA 1.5 mg demand-dose group, and 1 participant in the non-PCA comparison group. It lists 0 deaths in each group. The serious adverse event terms reported at 1.4% each are transient decrease in blood pressure and transient oxygen desaturation as measured by pulse oximetry. The record does not assign these terms to specific groups in the registry record.

These counts describe the events recorded in the registry, not a definitive comparison of safety between regimens. Small event counts provide limited information about the frequency of uncommon harms, and the record does not provide inferential comparisons or confidence intervals for these safety outcomes. The number of participants at risk is listed as 67, 70, and 69 for the respective groups; those figures should be interpreted as registry counts for the safety outcome, not as proof about the completeness of follow-up.

The registry also lists other adverse events affecting 1 participant in the PCA 1 mg demand-dose group and 0 in each of the other groups. The record does not provide further detail about these other events. Event counts alone do not establish causality, severity beyond the registry classification, or whether groups differ meaningfully in risk. They should be read as descriptive safety reporting within the information recorded.

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

The primary result describes average change in self-reported pain intensity from baseline to 30 minutes post treatment. Positive mean changes in all groups reflect decreases in NRS scores according to the registry's definition. The means are 3.8 for PCA with a 1 mg demand dose, 4.0 for PCA with a 1.5 mg demand dose, and 3.6 for the non-PCA comparison group. The associated confidence intervals express uncertainty about those group means.

The overall ANOVA p-value of 0.82 is the reported statistical comparison across groups. It does not show that the regimens are equivalent, and it does not quantify the size or precision of pairwise differences. The registry does not report estimable two-arm comparisons for this continuous endpoint. The posted summaries therefore support a description of group-level short-term changes, but not a complete account of pairwise effects.

The result does not answer whether changes persisted beyond 30 minutes, whether participants differed in later use of supplementary analgesia, or how the regimens compare on outcomes not reported. Need for supplementary analgesia is named as a secondary outcome, but a result is not available in the registry record for this account. The results also do not establish a treatment effect for an individual patient or make a recommendation about care.

The reported safety counts are descriptive. They include serious adverse events and deaths as recorded, but do not by themselves establish causation or precise comparative safety. Interpretation is also constrained by the lack of registry entries on missing data, analysis populations, and the full statistical plan. These limitations affect how broadly the posted results can be interpreted; they do not change the numerical values reported for the endpoint.

14. Why This Trial Matters Statistically

This trial offers a useful statistical example because it places two PCA dosing regimens alongside a non-PCA comparison group and reports a common short-term patient-reported endpoint. The design makes the broad question understandable: how do average NRS changes compare across the assigned groups over the specified interval? The endpoint's direction also matters: because change is baseline minus the 30-minute score, positive values indicate a decrease rather than an increase in pain intensity.

The results illustrate why descriptive summaries and inferential comparisons answer different questions. Means and confidence intervals describe each arm separately; an overall ANOVA tests the groups together. Neither presentation, by itself, supplies every pairwise estimate a reader may want. Here, the registry reports the overall p-value but not estimable two-arm continuous comparisons. This is a reminder to distinguish a group-level test from a direct contrast and to avoid reading a non-small p-value as proof of equivalence.

The record also highlights the role of completeness in statistical interpretation. Enrollment, endpoint group counts, safety counts, and a brief analysis description are recorded, but details about analysis populations, missing data, multiplicity, and the statistical plan are not. Those details help readers judge what population and assumptions a result represents. Their absence should be described as uncertainty about the record, rather than filled in through conjecture.

Finally, the short follow-up endpoint and sparse serious-event counts illustrate the limits of what one outcome and a small number of events can establish. Statistical interpretation should remain tied to the measure, time frame, and analyses actually recorded. The registry's posted results invite careful description, not claims beyond their scope.

15. 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 record gives a brief description of the trial and selected results, but not a full protocol or statistical analysis plan. It does not report the randomization procedure, allocation concealment, eligibility criteria, or details of the emergency-department setting. These omissions limit assessment of how assignment was implemented and which patients the results represent.

The primary endpoint is restricted to change from baseline to 30 minutes post treatment. The registry does not report longer-term pain outcomes or detailed results for the secondary outcome, need for supplementary analgesia. It also does not describe how the NRS was administered, how baseline values were handled analytically, or whether any covariates were included.

Although group counts accompany the primary endpoint, the record does not explain the difference between enrollment and endpoint counts or identify the analysis population. Missing-data methods, reasons for missing assessments, and sensitivity analyses are not reported. Without those details, it is not possible to judge whether the available endpoint observations represent all randomized participants in the intended way.

The inferential result is an overall ANOVA p-value; the record does not provide direct pairwise estimates or their confidence intervals. Model diagnostics, assumption checks, and any multiplicity approach are not reported. The safety information is also limited to recorded counts and selected event terms, without comparative estimates or detailed attribution. These limitations are specific to what is documented for this trial and should temper interpretation without implying that unreported methods were necessarily absent.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Efficacy of Patient Controlled Analgesia in the Emergency Department — NCT00910208.
• Registry record last updated 2019-12-27; status last verified 2019-12.
• Results first posted 2019-12-27.
• 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.

19. Record Summary

The registry identifies a completed, randomized, unmasked, parallel-group study of patient-controlled analgesia in the emergency-department setting, with enrollment of 211. The compared regimens were PCA with 1 mg or 1.5 mg morphine demand doses, each following a 0.1 mg/kg loading dose, and a non-PCA comparison group receiving the loading dose plus additional analgesia as needed.

The primary outcome was change in NRS pain intensity from baseline to 30 minutes post treatment. The registry reports group means and 95% confidence intervals, along with an overall ANOVA p-value of 0.82. It also lists serious adverse events and deaths by group. The record does not report estimable pairwise comparisons for the continuous primary endpoint, detailed results for the listed secondary outcome, or key information about analysis populations, missing data, multiplicity, and the full statistical plan.