A Health Economic Trial in Adult Patients Undergoing Laparoscopic Colectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Health Economic Trial in Adult Patients Undergoing Laparoscopic Colectomy (NCT02058290), a non-randomized phase 4 study. The primary outcome is Total Opioid Burden.

2. Clinical Question

3. Trial Design

This was a Phase 4, parallel-group clinical trial with non-randomized allocation and no masking. The registry lists 122 participants as enrolled. Group 1 was labeled IV morphine sulfate or sponsor-approved equivalent, and Group 2 was labeled EXPAREL. The group descriptions identify the former as standard of care and the latter as bupivacaine liposome injectable suspension. Because allocation was not randomized, differences between groups may reflect how participants entered or were selected for each group, as well as any treatment-related differences. The record does not describe the allocation process in detail.

The trial began in 2011-12, and primary completion is listed as 2012-09. Its status is terminated. The reason for termination is not reported in the registry record; the status alone does not explain why the trial ended or whether termination affected the planned analyses.

The primary outcome was total opioid burden in mg, described as a mean with standard deviation. It covered total IV and oral opioid consumption after surgery, beginning at wound closure and ending when the hospital discharge order was written or at Day 30, whichever came sooner. The record identifies two secondary outcomes: incidence of opioid-related adverse events and patient satisfaction with pain treatment after surgery. It lists 5 outcome measures and 3 analyses, but does not give a complete account of how each measure was analyzed.

Enrollment and efficacy-analysis populations are distinct in the record. For Group 1, 77 participants enrolled and 56 were included in the efficacy analysis set; for Group 2, 45 enrolled and 26 were included. The reasons for this difference and the handling of participants excluded from that analysis are not reported. No randomized comparison should be inferred from the parallel-group format: the explicit non-randomized allocation is central to interpreting the evidence.

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:

Analysis population for the primary outcome, as defined in the registry: Of the 77 subjects who were enrolled in Group 1, 56 were included in the efficacy analysis set. Of the 45 subjects who were enrolled in Group 2, 26 were included in the efficacy analysis set.

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.

Population: 122 subjects were enrolled. Of these, 105 subjects received study drug: 67 subjects received IV morphine sulfate or sponsor-approved equivalent and 38 subjects received EXPAREL.

6. Primary Endpoint

The registry lists the primary outcome as Total Opioid Burden, measured over Wound closure to time hospital discharge order is written or Day 30, whichever is sooner..

Total opioid burden measures the amount of opioid consumed after surgery, combining IV and oral use. The registry specifies mg as the unit and the mean as the summary measure, with standard deviation describing variation among observations. The measurement period starts at wound closure and ends at the time the hospital discharge order is written or Day 30, whichever comes sooner. It is therefore a bounded postsurgical measure, not a measure of opioid use over an unlimited follow-up period.

This endpoint was chosen to address the study's stated question about whether use of EXPAREL might reduce total opioid consumption compared with standard care. Opioid consumption is a continuous outcome: each participant's measured total can take a range of values rather than falling into only a yes-or-no category. Comparing group means can describe an average difference, while the standard deviation helps convey how much individual measurements vary within each group.

The endpoint's interpretation depends on knowing the actual group summaries, the estimated difference, and its uncertainty. Those primary outcome results are not reported in the registry record. Without them, the magnitude, direction, and precision of a between-group comparison cannot be described. The stated potential connection to hospital costs is a rationale in the study summary; a cost endpoint or cost result is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous, and the registry identifies the mean and standard deviation as its summary statistics. A mean represents the arithmetic average of participant-level measurements. A standard deviation describes the spread of those measurements around the mean; it is not the uncertainty in the estimated mean itself. To assess uncertainty in a comparison, readers generally need an estimate of the difference and a confidence interval or another inferential result. None of these primary comparison results is reported in the registry record.

What does a confidence interval convey?

General statistical explanation: a confidence interval gives a range of values compatible with the observed data under a specified statistical procedure and its assumptions. A narrower interval indicates greater precision than a wider interval, but neither width nor location alone establishes whether a result is clinically important. In this trial, the registry does not report a confidence interval for total opioid burden, so the precision of the estimated group difference cannot be evaluated.

Why does the allocation method matter?

General statistical explanation: random allocation helps make treatment groups comparable, on average, with respect to both recorded and unrecorded characteristics. With non-randomized allocation, the groups may differ before treatment in ways that influence the outcome. Statistical adjustment can address measured characteristics when they are recorded and modeled appropriately, but it cannot guarantee removal of differences that were not measured or were modeled inadequately. The registry identifies non-randomized allocation but does not report enough detail to assess the allocation process or any adjustment strategy.

What does the analysis population mean?

The efficacy analysis set is the subset the registry says was included in the primary efficacy analysis. It contains 56 of the 77 enrolled participants in Group 1 and 26 of the 45 enrolled participants in Group 2. These figures should not be confused with enrollment totals or with a complete account of follow-up. The record does not state why participants were not included, whether their outcome data were missing, or how their data were treated. General statistical explanation: excluding participants can affect a comparison if inclusion is related to treatment group, outcome, or participant characteristics. The direction and extent of any such effect cannot be inferred from the counts alone.

What can standard deviations tell readers?

General statistical explanation: standard deviations describe variability among individual measurements. A large spread can make a group mean less precise for a given amount of data, while a smaller spread can make it more precise, all else equal. For continuous outcomes, the shape of the measurement distribution and the presence of unusually high values may also matter. The registry identifies standard deviation as the dispersion measure, but does not report the primary means or standard deviations, so these features cannot be assessed for total opioid burden.

Why might over-dispersion matter?

General statistical explanation: over-dispersion arises when data vary more than a statistical model assumes. If a model underestimates variability, its standard errors and uncertainty intervals may be too small, making results appear more precise than they are. This issue can be relevant for count outcomes or other data with variability beyond a model's assumptions. The primary endpoint in this trial is a continuous total measured in mg, and the registry record does not report the model or diagnostics used. It is therefore not possible to say whether over-dispersion was assessed or relevant to the fitted analysis.

What is multiplicity?

General statistical explanation: multiplicity occurs when several outcomes, comparisons, or analyses are tested, increasing the chance that at least one result appears statistically notable by chance. Prespecified testing strategies can control or otherwise address that issue. The record names a primary outcome and two secondary outcomes, and lists 5 outcome measures and 3 analyses. It does not report whether a hierarchy, adjustment, or other multiplicity strategy was used. No claim about statistical significance should be made from the outcome list alone.

What are planning sample sizes?

General statistical explanation: a sample-size calculation describes how many participants might be needed under stated assumptions to detect a specified effect with a chosen error rate and power. Such calculations are planning illustrations, not observed results and not evidence that a study had a particular probability of success after it was completed. The planning illustrations associated with the analysis use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with target effects expressed as fractions of the observed effect. They are not the trial's own design justification. The registry does not report the trial's sample-size justification, and no planning illustration can substitute for the unreported primary outcome result.

In short, the design and endpoint description support an explanation of what the trial set out to measure, but the inferential details needed to judge the primary comparison are not reported in the registry record. The comparison's non-randomized nature and the difference between enrollment and efficacy-analysis counts are especially important when considering any result reported elsewhere.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("IV Morphine Sulfate or Sponsor-approved Equivalent", "EXPAREL")
n   <- c(56, 26)
m   <- c(96.47, 32.06)
sp  <- c(77.74, 53.16)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  IV Morphine Sulfate or Sponsor-approved Equivalent  56  96.470  77.740  75.651  117.289
CARM  EXPAREL  26  32.060  53.160  10.588  53.532

11. Multiplicity, Missing Data and Analysis Populations

The record identifies total opioid burden as the primary outcome and lists opioid-related adverse events and patient satisfaction with pain treatment after surgery as secondary outcomes. It also lists 5 outcome measures and 3 analyses. It does not report a multiplicity plan, such as a testing hierarchy or adjustment for multiple comparisons. Without that information, the handling of repeated outcome testing cannot be evaluated.

For the primary efficacy analysis, the registry states that 56 of the 77 participants enrolled in Group 1 and 26 of the 45 enrolled in Group 2 were included in the efficacy analysis set. It does not explain why the remaining enrolled participants were not included. Missing-data procedures, imputation methods, sensitivity analyses, and any assumptions about missingness are not reported in the registry record. The registry also does not describe a full analysis population definition beyond the efficacy-set counts.

These omissions limit assessment of both selection into the analysis and the robustness of any estimated effect. They do not establish that data were missing or that a particular analysis method was used; they mean the registry record does not report those details. Since the primary outcome values and inferential results are also not reported, there is no basis for judging whether multiplicity or missing-data choices affected a particular efficacy conclusion.

12. 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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: small intestinal obstruction (3.0%), urinary tract infection (3.0%), abdominal pain (2.6%), gastrointestinal perforation (2.6%), intestinal perforation (2.6%).

The registry reports serious adverse events affecting 9 of 67 participants at risk in the IV morphine sulfate or sponsor-approved equivalent group, and 5 of 38 participants at risk in the EXPAREL group. It also reports other adverse events affecting 53 of 67 and 15 of 38 participants at risk, respectively. These are counts of participants recorded as affected, not a statement that every event was caused by the assigned intervention. Because the trial was non-randomized, differences in the groups cannot be interpreted as causal treatment effects from these figures alone.

The registry lists the following serious-event terms with their recorded percentages: Small Intestinal Obstruction, 3.0%; Urinary Tract Infection, 3.0%; Abdominal pain, 2.6%; Gastrointestinal Perforation, 2.6%; Intestinal Perforation, 2.6%; and Cholecystitis Acute, 2.6%. The record does not make clear in this information the denominator or the context for these percentages, so they should not be reinterpreted as group-specific risks.

Deaths are not reported in the registry record. That is different from evidence that no deaths occurred. The record does not provide enough detail to determine whether participants experienced multiple events, how event severity was assessed, or whether a comparative safety analysis was conducted.

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

The registry record describes a study intended to compare postsurgical opioid consumption under EXPAREL and standard care in adults undergoing laparoscopic colectomy. It identifies the endpoint, its measurement period, the group labels, and the efficacy-analysis counts. It also reports serious and other adverse-event figures. Those details clarify what the study set out to examine and what safety information was recorded.

However, the primary endpoint results are not reported in the registry record. There is no reported group mean, standard deviation, estimated difference, confidence interval, or test result for total opioid burden. The study objective cannot be treated as a result, and the direction or size of an efficacy effect cannot be inferred from the stated purpose. A cost benefit is also not established: the summary mentions possible hospital-cost reduction as a rationale, but a cost result is not reported in the registry record.

The non-randomized allocation also limits interpretation. A difference between groups, if reported elsewhere, could reflect differences in participant characteristics or other factors linked to treatment selection, rather than treatment alone. The record does not supply enough detail to assess baseline comparability, allocation processes, or adjustment methods. The gap between enrollment and the efficacy analysis adds uncertainty because reasons for exclusion and handling of missing data are not reported.

The safety figures are descriptive. They do not by themselves show that one intervention caused more or fewer adverse events, particularly given the non-randomized design and the limited context for the serious-event percentages. Thus, the registry record supports a description of the trial's design and recorded safety counts, but not a conclusion about the efficacy of either approach or a causal safety comparison.

14. Why This Trial Matters Statistically

This trial illustrates why a stated clinical objective is not a substitute for a reported estimate. The registry describes an intended comparison of opioid consumption and a mean-based primary endpoint, but does not report the primary group values or the comparison's uncertainty. Without those results, readers cannot assess the magnitude or precision of the central outcome, regardless of the study's stated rationale.

It also shows why design labels matter. A parallel-group study is not necessarily randomized. Here, the registry explicitly identifies non-randomized allocation, so the groups cannot automatically be treated as exchangeable. Any comparison needs careful attention to how participants came to receive each approach and whether relevant differences were addressed. Those details are not reported in the registry record.

Finally, the difference between enrollment and efficacy-analysis counts highlights the importance of analysis populations and missing-data reporting. The record provides the counts but not the reasons for exclusions or their treatment in the analysis. This prevents readers from evaluating whether the efficacy population remained representative of the enrolled groups. Together, these features make the record useful for identifying the question, endpoint, and key interpretive constraints, while leaving the primary statistical conclusion unresolved.

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.

Several limitations specific to this trial are apparent from the registry record. First, the primary outcome values and between-group analysis are not reported. The mean opioid burden, standard deviation, effect estimate, uncertainty interval, and test result are all unavailable, so neither the direction nor precision of the primary comparison can be evaluated.

Second, the allocation was non-randomized and masking was absent. The record does not describe the allocation process or report enough information to assess how groups differed at baseline. Any group comparison is therefore vulnerable to selection differences and other sources of confounding that cannot be evaluated from the listed information.

Third, the efficacy analysis included fewer participants than were enrolled in each group. Although the record gives the enrollment and efficacy-set counts, it does not explain exclusions, describe missing-data handling, or report sensitivity analyses. This leaves uncertainty about how the analyzed groups relate to all enrolled participants.

Fourth, the trial status is terminated, but the reason for termination is not reported in the registry record. The record also does not provide the trial's sample-size justification, a detailed statistical analysis plan, or a multiplicity strategy. These omissions limit assessment of the planning and analysis decisions, but do not establish that any particular procedure was or was not used.

Finally, the serious-event percentages are listed without enough context in this record to identify their denominator or interpretation, and deaths are not reported. The safety counts should therefore be read descriptively, not as a causal comparison.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Health Economic Trial in Adult Patients Undergoing Laparoscopic Colectomy — NCT02058290.
• Registry record last updated 2014-05-14; status last verified 2014-04.
• Results first posted 2014-05-14.
• 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

This Phase 4 trial compared EXPAREL with standard care for adults undergoing laparoscopic colectomy. It used a parallel-group, non-randomized design without masking and is listed as terminated. Enrollment was 122. The primary outcome was mean total opioid burden in mg from wound closure until the hospital discharge order was written or Day 30, whichever came sooner.

The efficacy analysis included 56 of 77 enrolled participants in the standard-care group and 26 of 45 in the EXPAREL group. The registry record does not report the primary outcome results, the reason for termination, the reasons for efficacy-set exclusions, or the missing-data and multiplicity methods. It reports serious adverse events affecting 9 of 67 participants at risk in the standard-care group and 5 of 38 in the EXPAREL group. These descriptive safety figures do not establish a causal difference between groups.