Low-dose Ketamine vs Morphine for Vaso-occlusive Crisis in Sicklers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Low-dose Ketamine vs Morphine for Vaso-occlusive Crisis in Sicklers (NCT02434939), a randomized phase 4 study. The primary outcome is Maximal Change in NRS Pain Scores as a Percentage of Baseline NRS Pain Score..

2. Clinical Question

Non-inferiority is a question about whether the observed treatment difference is sufficiently small, under a prespecified rule, to rule out an unacceptable loss of effect. It is not established merely because a difference is not statistically significant. A non-inferiority interpretation depends on the margin selected in advance, the estimated treatment difference, its confidence interval, and the analysis plan. The margin and the analysis details are not reported in the registry record, so the stated aim cannot be assessed from the posted outcome information alone.

3. Trial Design

The registry describes a randomized, quadruple-masked, parallel-group phase 4 trial sponsored by Makerere University. Its planned enrollment was 240, and its status is completed. The recorded start is 2015-06 and the primary completion is 2016-01. Random allocation is intended to make treatment groups comparable at the start, while masking is intended to limit knowledge of treatment assignment from influencing care, outcome assessment, or other trial processes. The specific masking arrangements are not reported in the registry record.

Participants were assigned to one of two drug regimens: low-dose ketamine or morphine. Both were described as intravenous infusions delivered over 10 minutes using a syringe pump, with no more than 2 doses during a study period lasting 2 hours. The registry identifies the trial model as parallel, meaning the assigned groups are followed as separate groups rather than each participant receiving both study treatments in sequence. Further operational details, including the precise allocation procedure and any concealment procedures, are not reported in the registry record.

The stated primary aim was to assess whether ketamine was non-inferior to morphine for management of acute painful sickle cell crises in children. The registry also lists objectives concerning maximum change in NRS pain score and comparative safety. Secondary outcomes include time to maximal analgesic effect and duration of action, incidence of side effects including outlying vital signs, and incidence of treatment failure by treatment group. The record identifies four outcome measures and two analyses, but does not describe their complete statistical specifications.

The trial is marked completed, but completion status does not itself provide evidence about the direction or precision of the treatment comparison. Arm-level primary outcome summaries, an effect estimate, a confidence interval, and a test result are not reported in the registry record. The study’s non-inferiority margin, detailed statistical analysis plan, and sample-size justification are also 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.

Before assignment: Of the 800 patients, 314 met the inclusion criteria with a further 74 excluded. these included 28 with history stroke, 17 with SPO2 \< 90, 14 declined, 2 had altered mentation and 13 had undisclosed reasons. only 240 patients were randomized.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 3 patients in ketamine arm withdrew consent after 20 minutes in to the study while 1 patient in morphine arm was discontinued due to urticarial for fear of a worsened reaction if reexposed to the drug as he required a second dose

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 Maximal Change in NRS Pain Scores as a Percentage of Baseline NRS Pain Score., measured over 5, 10, 20,25,30, 40,45,50 60, 80, 100, 120 minutes post drug adminstration.

The primary endpoint is titled “Maximal Change in NRS Pain Scores as a Percentage of Baseline NRS Pain Score.” It concerns the largest observed change in a participant’s pain rating after study-drug administration relative to the rating taken just before administration. The NRS is a patient-reported scale from 0, representing no pain, to 10, representing the worst pain imaginable, using whole-number scores. The registry specifies a mean and standard deviation as the summary approach and describes the unit as percent change from baseline NRS score.

Repeated ratings allow the endpoint to capture the greatest recorded change during the observation period rather than relying on a single post-dose time point. This is relevant to an intervention intended for acute pain, because the magnitude of change and its timing can vary across participants. The registry schedules pain assessments at 5, 10, 20, 25, 30, 40, 45, 50, 60, 80, 100, and 120 minutes after drug administration. Its description also says recording stopped before 120 minutes if a participant requested a third dose, withdrew consent, or developed a severe adverse effect.

That stopping rule means the endpoint may not be observed over the same duration for every participant. How such incomplete follow-up was handled in the primary analysis is not reported in the registry record. Nor are the arm-level endpoint summaries or a treatment-effect estimate reported. The endpoint definition explains what the trial intended to measure; it does not, by itself, show the magnitude or precision of any treatment difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The trial’s stated primary outcome is continuous: it is summarized as a mean and standard deviation, and it is based on a change in a numerical pain rating. Statistical interpretation of such an outcome depends not only on the group averages but also on variability, the number of observations contributing to each average, and the analysis model. The registry record does not report the arm-level primary outcome summaries or the model used for the main comparison.

What does a mean and standard deviation describe?

In general, the mean gives a measure of the centre of a set of measurements, while the standard deviation describes how dispersed individual measurements are around that centre. A mean difference can summarize how group averages compare, but it does not convey the full spread of participant responses. The standard deviation helps describe that spread; it is not the same as the uncertainty in the estimated mean or the treatment difference. An inferential analysis would ordinarily report an estimate and a measure of its uncertainty, such as a confidence interval. Those comparative results are not reported in the registry record.

Why does the repeated measurement schedule matter?

Pain ratings were scheduled at multiple times after infusion, and the primary endpoint uses the maximum change from baseline. This creates a participant-level summary from repeated observations. In general, repeated measurements from the same person are related, rather than independent, and the way they are combined can affect interpretation. Selecting a maximum also makes the summary dependent on which observations were available and how “maximum change” was operationalized. The registry gives the timing schedule and a broad endpoint description but does not report a detailed derivation rule or the analysis model.

The record specifies ratings at 5, 10, 20, 25, 30, 40, 45, 50, 60, 80, 100, and 120 minutes after administration. It also says that ratings could stop before 120 minutes if a third dose was requested, consent was withdrawn, or a severe adverse effect developed. In general, unequal observation duration can affect a maximum-based measure: participants observed for different periods may have different opportunities for an extreme value to be recorded. That is a methodological consideration, not evidence that a particular bias occurred in this trial. The registry does not report how early stopping or incomplete ratings were handled in the primary analysis.

How should non-inferiority be assessed?

In general, a non-inferiority analysis asks whether the data exclude a treatment disadvantage larger than a clinically acceptable margin. The margin needs to be set before the results are examined and justified for the clinical question. The interpretation rests on the estimated difference and its confidence interval in relation to that margin; a nonsignificant conventional superiority test alone does not establish non-inferiority. The registry states the non-inferiority objective but does not report the margin, the direction convention for the comparison, the confidence interval, or the decision rule. Therefore the posted record does not permit a statistical determination of non-inferiority.

Analysis populations can also matter in non-inferiority trials. In general, exclusions, protocol deviations, crossover, and missing outcomes may affect treatment comparisons, so prespecified analyses and transparent reporting are important. The registry does not report which analysis populations were used, how participants were handled after discontinuation, or whether more than one population was used to assess robustness. These omissions prevent assessment of how the analysis addressed these issues.

What do the planning assumptions mean?

The registry describes sample-size planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. In general, sample-size planning asks how many participants would be needed under specified assumptions to detect a chosen effect with a chosen probability, subject to the calculation method. An illustration based on an observed effect is dependent on that effect estimate and the assumptions used; it is not a substitute for the trial’s design justification.

Sample-size calculations are planning tools, not measures of whether a completed trial succeeded. “Observed power” calculated from the final estimated effect is generally not an informative replacement for the effect estimate and its confidence interval. The registry record does not report the numerical planning outputs or a trial-specific sample-size justification. No numerical planning result can therefore be interpreted from the posted information.

What can the safety counts establish?

The record separates serious adverse events from other adverse events and lists the number at risk in each arm. In general, counts can describe how many events were recorded under the registry’s categories, but interpretation also depends on event definitions, observation time, collection procedures, and whether counts refer to participants with events or event episodes. The registry does not supply event-level details or a comparative safety analysis. The counts should therefore be read as descriptive registry entries, not as a complete account of relative safety.

10. Multiplicity, Missing Data and Analysis Populations

The primary endpoint is derived from repeated pain ratings, while the registry also lists secondary outcomes concerning timing and duration of analgesic effect, side effects including outlying vital signs, and treatment failure. Multiple outcomes or analyses can create multiplicity: in general, the more statistical questions examined, the greater the chance that at least one result appears notable by chance if no adjustment or hierarchy is specified. The registry identifies four outcome measures and two analyses, but does not report a testing hierarchy, multiplicity adjustment, or a detailed statistical analysis plan. The primary outcome itself is described as a maximum across scheduled measurements, but the record does not explain whether other endpoint definitions or time-specific comparisons were also examined.

Missing data are especially relevant because pain ratings could stop before the end of the 2-hour period if a participant requested a third dose, withdrew consent, or developed a severe adverse effect. The registry records that 3 patients in the ketamine arm withdrew consent after 20 minutes and that 1 patient in the morphine arm was discontinued after urticaria because of concern about re-exposure. It does not report how these observations were included in the primary analysis, how missing ratings were handled, or whether sensitivity analyses were conducted. The number of participants contributing to each scheduled assessment is not reported in the registry record.

The analysis populations are also not reported. In general, results can differ according to whether they include all randomized participants, only participants with available outcome measurements, or participants meeting specified protocol conditions. Such distinctions are important for interpreting a non-inferiority question, but the registry record does not describe the populations used or how deviations from assigned treatment were handled.

11. 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 1% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists 0 serious adverse events among 120 participants at risk in the low-dose ketamine group and 0 among 120 at risk in the morphine group. It separately lists 45 other adverse events in the ketamine group and 4 in the morphine group, with 120 participants at risk in each group. These are the posted counts; the record does not supply descriptions of the individual other adverse events, their severity, timing, duration, or relationship to study treatment.

In general, a count of other adverse events should not be treated as equivalent to a count of serious events. Nor does a difference in recorded counts, on its own, establish a causal treatment effect. Interpretation depends on how events were defined, whether the entries count people or episodes, how consistently events were collected, and the duration of observation. Those details and a statistical comparison are not reported in the registry record. The death entries are also not reported in the registry record, so they should not be read as zero deaths.

These figures are descriptive and do not cover all aspects of safety. They do not indicate the type of events behind the other-event totals, or how the trial assessed severity and attribution. The record also notes discontinuation of a morphine participant after urticaria, but does not report a complete event-level account for either group.

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

The registry record establishes that a randomized, parallel-group trial was conducted to compare low-dose ketamine with morphine for severe painful sickle cell crises in children. It describes the intended dosing, the primary pain endpoint, the repeated assessment schedule, several secondary outcomes, and selected adverse-event counts. These details make the research question and some aspects of the measurement plan understandable.

They do not establish the comparative result. The primary outcome’s group summaries, treatment-effect estimate, confidence interval, and inferential result are not reported in the registry record. The record also does not report the non-inferiority margin or the statistical rule used to decide whether the objective was met. It is therefore not possible to determine from the posted information whether the data supported non-inferiority, or to describe how precisely any treatment difference was estimated.

The stated primary measure is a maximum change in pain score relative to baseline, not a complete description of every aspect of pain relief. The registry also lists outcomes related to timing, duration, side effects, and treatment failure, but does not report comparative results for those outcomes. The posted adverse-event counts indicate the registry’s serious and other-event categories, but lack enough detail to characterize the other events or draw a causal conclusion.

In general, a completed trial and a planned enrollment do not guarantee that the results needed to answer the stated question are available in the registry. Likewise, an objective or hypothesis is not itself a finding. A clinical interpretation would require the reported outcome estimates, uncertainty, analysis populations, handling of missing data, and relevant protocol details. Those elements are not reported in the registry record. The appropriate conclusion is about the limits of the posted evidence, rather than about which treatment is preferable or whether either treatment works.

13. Why This Trial Matters Statistically

This trial raises several statistical issues that are common in acute-pain studies. Pain is measured repeatedly, participants may have different lengths of observation, and the primary endpoint selects a maximum change rather than a single measurement at a fixed time. Each choice shapes what the estimate means. A reader needs to know how repeated ratings were reduced to a participant-level outcome and how observations stopped early were treated. The registry gives the scheduled times and reasons recording could stop, but not the analysis details.

The non-inferiority objective also makes the missing statistical information especially consequential. In general, non-inferiority depends on a prespecified margin and an interval estimate that can be interpreted against that margin. A statement of the aim without the margin and result cannot answer the statistical question. This distinction is important because failure to show a difference is not the same as evidence that treatments are sufficiently similar under a defined criterion.

The trial record also illustrates why safety totals need context. The serious-event counts are reported as zero in each group, while other adverse-event counts are listed separately. Without event descriptions, collection rules, and a comparative analysis, those totals provide only a limited view of safety reporting. They should not be over-interpreted as a complete comparison.

More broadly, the registry contains a trial design and outcome framework but not the primary comparative result. Statistical transparency requires both a clear outcome definition and the estimates, uncertainty, populations, and methods that connect observations to conclusions. The distinction between what was planned, what was measured, and what was reported is central to reading clinical trial evidence accurately.

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 principal limitation for statistical interpretation is the absence of primary outcome results in the registry record. No group means or standard deviations, treatment-effect estimate, confidence interval, or primary test result are reported. The non-inferiority margin and detailed analysis plan are also not reported, leaving the stated primary aim unevaluable from the posted results.

The primary endpoint involves repeated assessments and a maximum change from baseline. The registry gives the scheduled times but does not provide a full calculation rule, the time-specific data, or the model used to analyze the outcome. It says measurements could stop early for a third-dose request, withdrawal of consent, or a severe adverse effect, but does not report how those incomplete observations were handled. The recorded withdrawals and discontinuation make the missing-data approach particularly relevant, yet the analysis populations and sensitivity analyses are not reported.

Safety reporting is limited to category counts and numbers at risk. Event descriptions, event-level details, severity and attribution information for other adverse events, and comparative safety analyses are not reported. The death entries are not reported in the registry record.

The record identifies secondary outcomes and the number of outcome measures and analyses, but does not specify the multiplicity approach or provide comparative findings for the secondary outcomes. It also describes planning illustrations without numerical outputs and does not report the trial’s sample-size justification. These omissions limit assessment of both the design assumptions and the completed analysis. They do not establish that the trial lacked such methods; they mean only that those details are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Low-dose Ketamine vs Morphine for Vaso-occlusive Crisis in Sicklers — NCT02434939.
• Registry record last updated 2016-08-03; status last verified 2016-06.
• Results first posted 2016-08-03.
• 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.

18. Record Summary

NCT02434939 is a completed, randomized, quadruple-masked, parallel-group phase 4 trial sponsored by Makerere University. The registry lists planned enrollment of 240 and records a start of 2015-06 and primary completion of 2016-01. It compared low-dose ketamine with morphine for severe painful sickle cell crises in children at Mulago Hospital.

The primary endpoint was maximal change in NRS pain score as a percentage of baseline, assessed after drug administration during a 2-hour period. The registry lists 0 serious adverse events among 120 at risk in each group, alongside 45 other adverse events in the ketamine group and 4 in the morphine group. The primary outcome results, non-inferiority margin, detailed statistical plan, and complete safety characterization are not reported in the registry record.