This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Two Dose Epidural Morphine for Post-cesarean Analgesia (NCT01844206), a randomized phase 4 study. The primary outcome is The Average Amount of Intravenous Morphine Patients Self-administered in the Second 24 Hours Post-surgery.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01844206 |
| Phase | Phase 4 |
| Condition | Pain, Morphine Adverse Reaction |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 5 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Columbia University |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing cesarean delivery were the intended population. The registry record says that 5 of 140 subjects were enrolled before the study terminated. It does not report participant characteristics or explain how the enrolled participants were distributed between the groups.
Intervention
The intervention was a second epidural morphine dose of 3mg, administered 24 hours after an initial intraoperative epidural morphine dose. The regimen was intended to be part of multimodal analgesia that included scheduled nonsteroidal anti-inflammatory drugs.
Comparator
The comparator was epidural saline 6ml, administered 24 hours after an initial epidural morphine dose of 3mg. The registry describes the saline group as receiving the same initial morphine dose before the later saline administration.
Primary question
The study planned to compare the amount of intravenous morphine participants self-administered by patient-controlled analgesia during the second 24 hours after surgery. The stated question was whether the additional epidural morphine dose would be associated with less intravenous morphine use than the saline regimen. The registry record contains no outcome analysis with which to answer that question.
The clinical question is therefore a comparison of two dosing regimens within a postoperative analgesia plan, rather than a comparison of epidural morphine with no morphine at all. Both groups were described as receiving an initial intraoperative epidural morphine dose; the randomized contrast concerned what was administered later. The registry identifies pain and morphine adverse reaction as conditions of interest, but does not report a completed efficacy analysis or results that establish the size or direction of any treatment difference.
3. Trial Design
The registry describes a phase 4, randomized, quadruple-masked, parallel-group study sponsored by Columbia University. The study title is “Two Dose Epidural Morphine for Post-cesarean Analgesia.” The record lists a start date of 2013-06 and a primary completion date of 2014-06, and gives the study status as terminated.
The planned comparison assigned participants to one of two groups. The epidural morphine group was described as receiving 3mg 24 hours after an initial dose. The epidural saline group was described as receiving 6ml of saline 24 hours after receiving epidural morphine 3mg. The brief summary places both regimens within multimodal analgesia that includes scheduled NSAIDs. Details of the initial-dose procedure beyond that description are not reported in the registry record.
The registry lists enrollment as 5, while the primary outcome description states that only 5 out of 140 subjects were enrolled before termination. It also says that the outcome data could not be summarized for the results data table, that no data analysis was carried out, and that the number analyzed was specified as “0” for each arm. Thus, the record distinguishes enrollment from analyzed participants: it reports some enrollment but no participants analyzed for the primary outcome.
The registry identifies one primary outcome and gives its timeframe as up to 48 hours post-operatively. The outcome description specifies that the comparison was to use an unpaired t-test for two groups. No group-level outcome values, estimate of a treatment contrast, confidence interval, or test result are reported. Other protocol details, including the reasons for termination, are not reported in the registry record.
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
| Stage | Epidural Morphine | Epidural Saline |
|---|---|---|
| STARTED | 2 | 3 |
| COMPLETED | 2 | 2 |
| NOT COMPLETED | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Data could not be summarized to include in the data table because only 5 out of 140 subjects were enrolled prior to study termination, and no data analysis was carried out. As instructed, we are specifying zero ("0") for the Number of Participants Analyzed in each Arm/Group and leaving the data fields blank.
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.
| Characteristic | Unit | Epidural Morphine | Epidural Saline | Total |
|---|---|---|---|---|
| Participants analysed | 2 | 3 | 5 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 2 | 3 | 5 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 2 | 3 | 5 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 2 | 3 | 5 |
| Region of Enrollment: United States | participants | 2 | 3 | 5 |
6. Primary Endpoint
The registry lists the primary outcome as The Average Amount of Intravenous Morphine Patients Self-administered in the Second 24 Hours Post-surgery, measured over Up to 48 hours post-operatively.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the average amount of intravenous morphine participants self-administered through a patient-controlled analgesia pump during the second 24 hours after surgery. The registry describes the quantity as morphine in milligrams, although the outcome unit field itself is null. Its stated timeframe is up to 48 hours post-operatively.
This measure was chosen to reflect participants’ use of additional systemic opioid analgesia during the period targeted by the second epidural dose. In general, a patient-controlled analgesia measure records medication use under the participant’s control, and can serve as a quantitative outcome for comparing analgesic regimens. It is not identical to a direct measure of pain intensity: medication use may reflect several influences, and the registry does not report a pain score as the primary endpoint.
The planned contrast was between the group receiving the second epidural morphine dose and the group receiving saline after the shared initial epidural morphine dose. The registry says the average amount would be compared using an unpaired t-test for two groups. It does not provide the observed averages, variability, or an estimate of the difference. Because no outcome analysis was carried out, the endpoint’s observed value and the precision of any group comparison are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the registry contains no analyzed primary outcome results. It reports that only 5 of 140 subjects were enrolled before termination and says that no data analysis was carried out. The number of participants analyzed is recorded as “0” in each arm, and no primary outcome values are presented. Consequently, the record does not establish an observed difference in intravenous morphine use between the groups.
There is no treatment-effect estimate, confidence interval, or p-value for the primary outcome. Without those quantities, the direction, magnitude, and precision of a possible group difference cannot be described from this record. The absence of an analysis is not evidence that the groups had the same outcome, nor is it evidence that one regimen resulted in greater or lesser morphine use.
The small enrollment relative to the stated 140 subjects is important for interpretation, but it should not be converted into a conclusion about efficacy or statistical power. No outcome data were analyzed, so there is no observed effect on which to base a trial result. Any sample-size illustration based on an observed effect is not an observed-power calculation and cannot restore the missing trial comparison. It is a planning exercise, not evidence about what happened among participants.
The adverse-event record lists 5 people at risk in each group, with 0 serious adverse events and 0 other adverse events recorded in each. Those figures should be read as registry entries, not as a comparative safety analysis. The primary outcome description separately says 5 people in total were enrolled and 0 were analyzed in each arm. The record does not explain the apparent difference between the enrollment statement and the per-group safety counts, and it provides no inferential comparison for adverse events.
Randomization and masking describe intended design features, but they do not substitute for outcome data. With no reported analyzed primary outcome, the trial record cannot quantify the comparative analgesic outcome it was designed to assess. The registry also does not report a reason for termination or further details that would clarify the conduct of the study after enrollment stopped.
9. Statistical Methods Explained
The registry specifies an intended randomized, quadruple-masked, parallel-group comparison and names an unpaired t-test for the primary outcome. These are descriptions of the planned design and analysis. They should be distinguished from completed analysis: the record explicitly states that no data analysis was carried out and reports no primary outcome result.
What does randomization contribute?
General: Randomization assigns participants to comparison groups by chance. When implemented as intended, it is used to reduce systematic differences between groups at assignment, so that a later outcome contrast can be interpreted as a comparison of the assigned regimens. Randomization does not guarantee that groups will be identical, especially in a small study, and it does not itself produce evidence of a treatment effect. In this trial, the registry says the allocation was randomized, but does not report the allocation sequence method or the group sizes among enrolled participants.
What does masking mean?
The registry labels the study quadruple-masked. General: Masking is intended to limit the influence of knowledge about assigned treatment on participants, clinicians, outcome assessment, or other study processes, depending on who is masked. The registry does not specify which roles were included in the quadruple-masking designation or how masking was maintained. A masking label describes the intended design; with no reported analysis, it cannot be used to infer that masking was successful or that it affected outcomes.
Why use an unpaired t-test?
The primary outcome description names an unpaired t-test to compare two groups. General: An unpaired t-test evaluates whether the group means differ, treating observations in the groups as independent. It uses the observed means and variability to estimate uncertainty under its model assumptions. Its appropriateness depends on the data and analysis conditions; the registry does not report diagnostics, transformations, adjustments, or an alternative analysis. It also does not report the test statistic, degrees of freedom, p-value, or confidence interval. Since no analysis was conducted, there is no t-test result to interpret.
A test result alone would not convey the full size and precision of a difference. General: An estimate describes the observed contrast, while a confidence interval gives a range of values compatible with the data and model at a stated confidence level. A p-value addresses compatibility of data with a specified null model; it does not measure the probability that a treatment works. None of these primary-outcome quantities is reported in the registry record.
Why can a mean comparison be difficult with sparse data?
General: A mean can be sensitive to unusually high observations, and a t-test’s uncertainty estimate depends on assumptions about the data or an approximation that becomes more dependable with adequate information. If an outcome is highly skewed or contains many zero values, a mean-based analysis may not capture all features of the distribution. Morphine use is recorded as an amount, but the registry provides no participant-level values or distribution summaries. It is therefore not possible to assess skewness, outliers, or whether the planned model’s assumptions were reasonable in this study.
General: Over-dispersion means that the observed variability exceeds what a chosen statistical model expects. When present, it can make uncertainty estimates too small if not addressed, which can distort intervals and tests. The registry does not report a distributional model or any assessment of over-dispersion. This is a general consideration rather than a finding about the trial, because there are no posted outcome data to evaluate.
How should planning illustrations be read?
General: A sample-size calculation asks how much information a future or planned study may need to detect a specified effect under stated assumptions. The registry’s description of the planning illustration says it uses a two-sided significance level of 0.05, equal allocation, a normal approximation, and a fraction of the observed effect. These are assumptions for that illustration, not evidence that the trial used them in its original design. The registry does not report the trial’s own sample-size justification.
A planning illustration based on an observed effect is not observed power. Observed power is sometimes calculated retrospectively from an estimated effect, but it does not replace an estimate and confidence interval, and it is not a result of this trial. Since the registry reports no analyzed primary outcome or observed effect, a planning illustration cannot be interpreted as demonstrating the trial’s ability to answer its clinical question. The record also does not report interim analyses or stopping rules.
Overall, the listed methods identify how the comparison was intended to be structured and tested, but not what the data showed. The actual analysis details beyond the named unpaired t-test, including any adjustments or handling of departures from assumptions, are not reported in the registry record. The intended statistical method therefore cannot be treated as a completed statistical result.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary outcome measure: average intravenous morphine self-administered during the second 24 hours after surgery. It lists one outcome measure and no analyses. The outcome is described over a stated postoperative timeframe, but the record does not report multiple analyzed endpoints or a family of statistical tests.
Multiplicity arises when several outcomes, comparisons, time points, or repeated tests are considered; without a plan, the chance of an apparently unusual finding can increase. General: Statistical plans may address this by identifying a primary comparison or adjusting inference across multiple tests. The registry does not report a multiplicity-adjustment plan or an interim-analysis plan. Since no analyses were carried out, there is no reported set of p-values from which to assess multiplicity in practice.
The outcome description says the data could not be summarized for the results data table because only 5 of 140 subjects were enrolled before termination. It further says no data analysis was carried out and specifies “0” participants analyzed in each arm. The record does not describe individual missing outcome values, reasons for missingness, or an approach to missing data. These details are not reported in the registry record.
It is therefore not possible to determine whether the endpoint was measured for every enrolled participant, whether any observations were excluded, or whether the analysis population was defined by assignment, treatment received, or another rule. General: An analysis population defines which participants contribute to a particular estimate; different definitions can answer different questions. Here, the registry’s zero analyzed count and absence of an outcome analysis prevent comparison of such populations. The per-group adverse-event counts do not supply a primary-outcome analysis population or resolve the missing outcome information.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Epidural Morphine | 0 | 5 | 0.0% |
| Epidural Saline | 0 | 5 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Epidural Morphine | 0 of 5 |
| Epidural Saline | 0 of 5 |
The adverse-event record lists 5 people at risk in the epidural morphine group and 5 in the epidural saline group. For each group, it records 0 serious adverse events and 0 other adverse events. No serious adverse-event terms are listed. Death counts are null, which is not the same as a reported count of zero.
These are descriptive registry entries, not evidence from a comparative safety analysis. The record does not provide an adverse-event analysis, estimates of between-group differences, or uncertainty intervals. It also does not explain the apparent mismatch between the statement that 5 subjects in total were enrolled and the listing of 5 at risk in each group. The reported at-risk counts should therefore be presented as recorded rather than reconciled by assumption.
General: Observing no recorded events in a small group does not establish that an event cannot occur or precisely characterize its frequency. The figures describe what the registry lists for the recorded groups; they do not support a broad conclusion about comparative safety. The registry does not report additional safety details, event definitions, or follow-up information that would clarify how completely adverse events were captured.
12. What the Result Does, and Does Not, Mean
The trial was designed to test whether adding a second epidural morphine dose 24 hours after an initial intraoperative dose would change intravenous morphine use during the second 24 hours after cesarean surgery, compared with epidural saline after the initial dose. That is the question the planned primary endpoint could have addressed.
The registry record does not answer that question. It reports that only 5 of 140 subjects were enrolled before termination, that no data analysis was carried out, and that “0” participants were analyzed in each arm. There are no reported outcome averages, group contrast, confidence interval, or p-value. Thus, there is no basis in the record for saying which group used more or less intravenous morphine, or by how much.
This absence of an analysis should not be interpreted as a finding of no difference. A finding of little or no difference would require analyzed data and an estimate precise enough to distinguish a small contrast from meaningful uncertainty. The registry supplies neither. Nor does the study’s randomized and masked design alone show that either regimen had a particular outcome.
The record does establish that a comparison was planned, identifies the groups and endpoint, and records that enrollment stopped before the stated total of 140 subjects. It also records adverse-event counts, but those entries do not constitute a comparative safety analysis. The reasons for termination, participant-level outcomes, and further details about missing data are not reported in the registry record.
Any sample-size illustration associated with an observed effect is a planning aid, not a substitute for results and not observed power. It cannot turn this terminated, unanalyzed study into evidence for or against a treatment difference. The statistically appropriate conclusion is limited: the registry documents the intended study question and incomplete enrollment, but does not report an analyzed answer.
13. Why This Trial Matters Statistically
This trial is statistically instructive because a clearly framed randomized comparison does not guarantee an interpretable efficacy estimate. The registry specifies two regimens, a primary outcome, a proposed test, and masking, but reports that enrollment stopped after 5 of 140 subjects and that no analysis was performed. Those details separate study design from study findings.
With no outcome estimate, readers cannot judge the magnitude or precision of a difference. That is distinct from a result that is statistically non-significant: no primary-outcome test result is reported at all. This distinction matters because absence of evidence from an unanalysed endpoint should not be recast as evidence that the regimens produce equivalent outcomes.
The record also illustrates why sample-size planning and trial results answer different questions. A planning exercise depends on assumptions about the effect to detect and statistical model. It does not describe the observed comparison, and it cannot compensate for absent outcome data. Likewise, a count of participants enrolled is not the same as a count contributing to an analysis; the registry gives an enrollment statement and separately records zero analyzed participants in each arm.
Finally, transparent reporting of what is missing is itself useful. The registry identifies the intended endpoint and states that no analysis was carried out, allowing readers to avoid treating an incomplete study as a positive, negative, or equivalence finding. Important details—including the reason for termination and the handling of individual outcome data—are not reported in the registry record. The case underscores that statistical interpretation depends not only on a protocol’s planned methods, but also on completed measurement, analysis, and reporting.
14. 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 most consequential limitation is that the planned primary outcome has no reported analyzed results. The registry states that only 5 of 140 subjects were enrolled before termination, that data could not be summarized for the primary outcome, and that no data analysis was carried out. It records “0” participants analyzed in each arm. Without analyzed outcome data, the clinical comparison cannot be estimated.
The record does not report why the study was terminated or whether the termination was related to recruitment, logistics, safety, or another reason. No such explanation should be inferred. It also does not report group sizes among the enrolled participants, participant characteristics, or individual outcome measurements. As a result, readers cannot assess the composition of the enrolled sample or how closely the participants reflect the intended population.
The primary outcome description names an unpaired t-test, but does not report further analysis details such as assumption checks, adjustments, or missing-data methods. The record provides no outcome variability, confidence interval, or treatment-effect estimate. These omissions prevent assessment of statistical precision and the distribution of the outcome.
The adverse-event entries list 5 people at risk in each group despite the separate statement that 5 subjects in total were enrolled. The registry does not reconcile these figures. Although 0 serious and 0 other adverse events are recorded for each group, the entries are not accompanied by a comparative analysis or detail on event capture. The registry also does not report death counts as numeric values.
Finally, the record does not report the original sample-size justification, interim analyses, stopping rules, or a multiplicity plan. A planning illustration based on an observed effect should not be treated as the study’s own design justification or as an analyzed result.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Two Dose Epidural Morphine for Post-cesarean Analgesia — NCT01844206.
- Registry record last updated 2015-12-23; status last verified 2015-11.
- Results first posted 2015-12-23.
- 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.
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18. Record Summary
The registry describes a phase 4, randomized, quadruple-masked, parallel-group study sponsored by Columbia University. It planned to compare a second epidural morphine dose of 3mg with epidural saline 6ml, each given 24 hours after an initial epidural morphine dose, within a multimodal post-cesarean analgesia regimen.
The primary endpoint was the average amount of intravenous morphine self-administered during the second 24 hours after surgery, with an unpaired t-test named for the planned comparison. The study started in 2013-06, had a primary completion date of 2014-06, and is listed as terminated.
The record says only 5 of 140 subjects were enrolled before termination and that no outcome analysis was carried out. It reports “0” participants analyzed in each arm and contains no primary-outcome estimate or test result. The reason for termination and further details about missing outcome data are not reported in the registry record.