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 Study to Find the Dose of Rapidly Administered Ketamine for Brief Painful Procedures in Children (NCT01669642), a na na study. The primary outcome is Median Effective Dose (ED50) and ED95 of Rapidly Administered Ketamine.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01669642 |
| Phase | NA |
| Condition | Abscess, Fracture |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 111 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Washington University School of Medicine |
| Results posted | Yes |
2. Clinical Question
Population
Children in age groups 2-5, 6-11 and 12-17 undergoing abscess drainage or fracture reduction. The primary outcome description says 100 children were enrolled in 5 groups; the overall enrollment field reports 111. How these figures relate is not reported in the registry record.
Intervention
Rapidly administered ketamine for procedural sedation. The registry describes ketamine as the intervention and identifies no other study treatment.
Comparator
There is no control or comparison group. The record describes a single-group study, with no allocation and no masking.
Primary question
What are the median effective doses associated with effective sedation in 50% and 95% of children, assessed separately by age group and procedure? The primary outcome timeframe is dose administration through 5 minutes. The actual dose estimates are not reported in the registry record.
The study concerns dose estimation, rather than a comparison of ketamine with another drug or sedation strategy. Its stated aim is to estimate the dose associated with effective sedation for children undergoing abscess drainage or fracture reduction. The registry describes estimates for three age groups and the two procedure types, with ED50 and ED95 as the measures of interest.
These questions are clinically and statistically distinct from asking whether one treatment is better than another. In a single-group dose-estimation study, the focus is the relationship between administered dose and sedation response within the studied participants. Without a control group, the record cannot support a randomized comparison with another treatment. The registry does not report the actual ED50 or ED95 estimates, or the response data needed to assess how precise those estimates are.
3. Trial Design
The registry classifies this as a completed, single-group study of ketamine, with no masking and no allocation to competing treatment arms. It lists abscess and fracture as the conditions and identifies abscess drainage and fracture reduction as the procedures of interest. The study is described as involving children in age groups 2-5, 6-11 and 12-17. The intervention is rapidly administered ketamine; the record says there is no control or comparison group.
The registry lists enrollment as 111. The primary outcome description separately says 100 children were enrolled in 5 groups based on age and procedure. The relationship between these enrollment statements is not reported in the registry record. The adverse-event information lists five groups, each identified by procedure and age group; it does not list a fracture-reduction group for ages 12-17 or an abscess-drainage group for ages 12-17. The record does not explain the group coverage or how it relates to the primary outcome description.
The study start is recorded as 2012-04, and primary completion as 2014-08. The phase is listed as NA. The record names Washington University School of Medicine as sponsor. These administrative details identify the registered study but do not describe its statistical analysis.
The single-group design is important when interpreting the results. Dose-response estimates can describe the observed sedation experience under the study conditions, but they are not treatment-effect estimates from a controlled comparison. The registry does not report a statistical analysis plan, a sample-size justification, or details of dose assignment and response modeling. Those design and analysis details should therefore not be inferred from the study objective or from the outcome definitions.
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 | Fracture Reduction Group 2-5 Years | Fracture Reduction Group 6-11 Years | Fracture Reduction Group 12-17 Years | Abscess Drainage Group 2-5 Years | Abscess Drainage Group 6-11 Years | Abscess Drainage Group 12-17 Years |
|---|---|---|---|---|---|---|
| STARTED | 20 | 20 | 20 | 21 | 20 | 10 |
| COMPLETED | 20 | 20 | 20 | 20 | 20 | 0 |
| NOT COMPLETED | 0 | 0 | 0 | 1 | 0 | 10 |
Analysis population for the primary outcome, as defined in the registry: 100 children were enrolled in 5 different groups depending on the age and type of procedure.
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 | Fracture Reduction Group 2-5 Years | Fracture Reduction Group 6-11 Years | Fracture Reduction Group 12-17 Years | Abscess Drainage Group 2-5 Years | Abscess Drainage Group 6-11 Years | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 20 | 20 | 20 | 20 | 20 | 100 | |
| Age, Continuous | years | 4.8 (2.9 to 5.9) | 9.2 (6 to 11.9) | 13.7 (12.6 to 16.9) | 2.9 (2 to 5.1) | 7.2 (6.4 to 11.9) | 7.2 (2.9 to 11.9) |
| Sex: Female, Male: Female | Participants | 9 | 6 | 1 | 8 | 11 | 35 |
| Sex: Female, Male: Male | Participants | 11 | 14 | 19 | 12 | 9 | 65 |
| Race/Ethnicity, Customized: african american | Participants | 5 | 2 | 8 | 9 | 8 | 32 |
| Race/Ethnicity, Customized: Caucasian | Participants | 13 | 1 | 2 | 10 | 12 | 38 |
| Race/Ethnicity, Customized: other | Participants | 2 | 17 | 10 | 1 | 0 | 30 |
| Patients who received Opioids prior to sedation | Participants | 19 | 18 | 19 | 0 | 0 | 56 |
| time between opioid administration and sedation start time | minutes | 116 (20 to 383) | 96 (1 to 251) | 129 (27 to 401) | 0 (0 to 0) | 0 (0 to 0) | 116 (1 to 401) |
| fracture characteristics: Non displaced fracture | Participants | 10 | 2 | 9 | 0 | 0 | 21 |
| fracture characteristics: displaced fracture but not overriding | Participants | 6 | 11 | 7 | 0 | 0 | 24 |
| fracture characteristics: displaced fracture and overriding | Participants | 4 | 7 | 4 | 0 | 0 | 15 |
| fracture characteristics: no fracture | Participants | 0 | 0 | 0 | 20 | 20 | 40 |
6. Primary Endpoint
The registry lists the primary outcome as Median Effective Dose (ED50) and ED95 of Rapidly Administered Ketamine, measured over Dose administration through 5 minutes.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | mg/kg of ketamine dose |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled “Median Effective Dose (ED50) and ED95 of Rapidly Administered Ketamine.” It is measured in mg/kg of ketamine dose, with the timeframe defined as dose administration through 5 minutes. The registry defines ED50 as the dose associated with effective sedation in 50% of patients and ED95 as the dose that can provide effective sedation in 95% of children undergoing abscess drainage or fracture reduction. It says ED95 will be calculated separately for the three age groups and both procedures.
These dose thresholds are useful because they express the dose-response question in terms of the proportion of patients expected to meet a specified sedation outcome. ED50 describes a midpoint of the response distribution, while ED95 targets a higher response proportion. As a general statistical point, estimating a dose associated with a response proportion requires information about both the administered doses and the corresponding sedation outcomes. The registry record does not report the dose estimates or the underlying response data, so the endpoint’s observed values and precision cannot be assessed.
The outcome metadata identify the parameter as a median and the dispersion as full range. The record does not report confidence intervals or explain the statistical procedure used to obtain the dose estimates. The endpoint definition therefore states what the investigators intended to estimate, but it does not supply the results needed to judge how stable or precise those estimates are.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study’s objective and outcome definitions, but it does not report the primary ED50 or ED95 results. Consequently, no specific effective dose can be described from this record, and the precision of any estimate cannot be assessed. The record also does not provide a confidence interval or other uncertainty measure for the primary endpoint.
The central interpretation should remain focused on estimation, not comparative effectiveness. This was a single-group study with no control or comparison group. Its objective was to characterize dose levels associated with specified sedation response proportions for different ages and procedures. It was not designed in the registered record as a randomized comparison of ketamine against another treatment. Differences across age or procedure groups, even if estimates were available, would not by themselves establish a causal effect of age or procedure.
The registry describes ED50 as the dose that achieves effective sedation in 50% of patients and ED95 as a dose expected to provide effective sedation in 95% of children. These are target response proportions in the endpoint definitions, not reported study findings. They should not be read as evidence that those proportions were achieved in the observed groups. The actual dose values, response counts and methods used to derive the estimates are not reported in the registry record.
The registry also lists secondary outcomes of vomiting and the number of participants with a Wisconsin Sedation Scale score of 2 or less at 1 minute after the first ketamine dose. Outcome definitions alone do not show how often those events or responses occurred. Their results are not reported in the registry record. The same limitation applies to any conclusions about the frequency or timing of recovery, which are discussed in the study summary but not reported as results in the registry record for interpretation.
The enrollment information warrants care. The record lists 111 participants enrolled, while the primary outcome description says 100 children were enrolled in 5 groups. The relationship between those statements is not reported in the registry record, so they should not be reconciled by assumption. The adverse-event listing presents group-specific information for five age-and-procedure groups, but the record does not explain how those group entries relate to the full enrollment or primary analysis population.
For safety, the listed groups show zero participants with serious adverse events and zero deaths. Other reported events are listed by group, but the record does not define those events further in the details. These registry entries describe reported counts; they do not establish comparative safety, because there is no control group. They also cannot substitute for a detailed account of event definitions, observation periods, completeness of follow-up or how participants were included in the safety summaries.
Overall, the posted information supports a description of the study question, design and planned dose-response measures. It does not support a numerical conclusion about the effective dose, the certainty of that dose estimate, or a comparison with another sedation approach. Missing result details should be treated as not reported in the registry record, not as evidence that no outcome occurred or that an analysis found no effect.
9. Statistical Methods Explained
The registry identifies a dose-estimation objective but does not describe the statistical procedure used to estimate the primary endpoint. The concepts below explain how such measures are generally interpreted; they are not claims about the investigators’ actual analysis.
What do ED50 and ED95 represent?
In general, ED50 and ED95 are dose levels associated with specified response probabilities. ED50 corresponds to the dose at which the modeled probability of the defined response is 50%; ED95 corresponds to a dose associated with a 95% probability. Such estimates summarize a dose-response relationship rather than compare two treatment arms. Their interpretation depends on a clear definition of effective sedation and on appropriate data across the dose range.
A dose-response estimate is not the same as an observed dose that worked for a particular participant. It is a summary derived from response information across participants. The registry gives the endpoint definitions and the intended age and procedure groupings, but it does not report the response observations, the dose values administered, or the model used. It is therefore not possible to establish from the registry record whether a particular modeling approach was used or how the estimates were calculated.
Why does uncertainty matter?
Any estimated dose is subject to sampling uncertainty. A confidence interval, when reported, communicates a range of values compatible with the data and the analysis assumptions. A narrow interval indicates greater precision than a wide interval, although precision does not guarantee that the estimate is free of bias or that the analysis assumptions are appropriate. The registry record does not report confidence intervals for ED50 or ED95, so the precision of the primary estimates is not available.
In general, estimating a high response target such as ED95 can be especially sensitive to how well the data inform the upper part of the dose-response curve. If the observed data do not adequately cover that region, estimates can depend strongly on modeling assumptions. This is a general statistical consideration, not a statement about the data collected in this study. The registry record does not describe the dose distribution or model diagnostics.
What does the reported summary type tell readers?
The primary outcome metadata identify the parameter as a median and dispersion as full range. A median is a measure of central tendency; the full range describes the span from the smallest to the largest observed value in the summarized data. These descriptions do not give the actual estimates. They also do not provide the same information as a confidence interval for an estimated dose. Since no result values are reported for the endpoint, readers cannot assess either the dose distribution or the uncertainty around the dose-response estimates.
Why is the single-group design relevant?
In general, an uncontrolled study can describe outcomes observed after an intervention, but it cannot isolate the intervention’s effect from other explanations using a concurrent randomized comparison. This study’s registry record identifies a single group and says there is no control or comparison group. The dose-estimation objective is therefore distinct from a claim that ketamine performs better or worse than another sedative or administration strategy. No such comparative conclusion can be derived from the registered design.
Age and procedure are part of the intended estimation structure. The primary outcome description says ED95 is to be calculated separately for the three age groups and for both procedures. Separate estimates may be useful for describing dose-response patterns in distinct clinical settings, but they can also be less precise when each subgroup contains less information. The record does not provide subgroup estimates or their uncertainty, and the listed adverse-event groups do not document every age-and-procedure combination named in the primary outcome description.
How should planning calculations be read?
In general, sample-size calculations are planning tools based on assumptions about an effect, variability, allocation and the desired statistical properties of a future study. They are not observed outcomes and do not show whether a study’s result was precise. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation and effects expressed as fractions of an observed effect. Those assumptions are described as an illustration computed from the observed effect, not as the trial’s own design. The registry does not report the resulting planning values in the record. Any such illustration should not be interpreted as observed power for this single-group study.
More broadly, the registry does not report the statistical analysis plan, the dose-response model, handling of repeated or incomplete observations, criteria for effective sedation, or a prespecified approach to estimating uncertainty. These are not details that can be inferred from the endpoint title. Until those methods and the actual results are reported, the primary endpoint remains a stated analysis objective rather than an assessable numerical finding.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and secondary outcomes, but a statistical plan for handling multiple outcomes or subgroup estimates is not reported in the registry record. The primary outcome description calls for estimates across age groups and procedures, and the secondary outcomes include vomiting and the number of participants with a Wisconsin Sedation Scale score of 2 or less at 1 minute after the first ketamine dose. The record does not state whether these analyses were prespecified, how they were prioritized, or whether any adjustment for multiple testing was planned.
As a general statistical point, examining multiple outcomes or subgroups can increase the chance of finding an apparently notable result by chance. The concern depends on the analysis strategy and the inferential claims being made; it cannot be assessed from outcome names alone. No analysis results are reported in the registry record, so there are no reported tests or estimates to evaluate for multiplicity.
Missing-data methods and analysis populations are also not reported in the registry record. There is no description of how participants with incomplete sedation assessments, missing dose information or incomplete follow-up were handled. The record does not state whether the primary analysis included all enrolled children, only those with an evaluable procedure, or another defined group. The enrollment field reports 111, while the primary outcome description refers to 100 children in 5 groups; how these figures relate is not reported.
In general, missing observations can affect an estimate if the participants with missing information differ systematically from those with observed outcomes. Without the amount, reasons and handling of missing data, readers cannot assess that possibility. The registry record also does not report sensitivity analyses or a plan for addressing missingness. These omissions limit interpretation of both the intended dose estimates and the listed secondary outcomes.
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 |
|---|---|---|---|
| Fracture Reduction Group 2-5 Years | 0 | 20 | 0.0% |
| Fracture Reduction Group 6-11 Years | 0 | 20 | 0.0% |
| Fracture Reduction Group 12-17 Years | 0 | 20 | 0.0% |
| Abscess Drainage Group 2-5 Years | 0 | 20 | 0.0% |
| Abscess Drainage Group 6-11 Years | 0 | 20 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Fracture Reduction Group 2-5 Years | 0 of 20 |
| Fracture Reduction Group 6-11 Years | 0 of 20 |
| Fracture Reduction Group 12-17 Years | 0 of 20 |
| Abscess Drainage Group 2-5 Years | 0 of 20 |
| Abscess Drainage Group 6-11 Years | 0 of 20 |
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 |
|---|---|
| Fracture Reduction Group 2-5 Years | 7 of 20 |
| Fracture Reduction Group 6-11 Years | 5 of 20 |
| Fracture Reduction Group 12-17 Years | 7 of 20 |
| Abscess Drainage Group 2-5 Years | 3 of 20 |
| Abscess Drainage Group 6-11 Years | 2 of 20 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Fracture Reduction Group 2-5 Years | Fracture Reduction Group 6-11 Years | Fracture Reduction Group 12-17 Years | Abscess Drainage Group 2-5 Years | Abscess Drainage Group 6-11 Years |
|---|---|---|---|---|---|---|
| vomiting | Gastrointestinal disorders | 7 of 20 | 4 of 20 | 4 of 20 | 3 of 20 | 1 of 20 |
| dysphoria, ag | Nervous system disorders | 0 of 20 | 1 of 20 | 3 of 20 | 0 of 20 | 1 of 20 |
The registry’s adverse-event entries list five age-and-procedure groups. For each listed group, 20 participants are recorded as at risk for serious adverse events, with zero affected; deaths are also recorded as zero in each group. The other-event counts are listed as 7 for fracture reduction ages 2-5, 5 for fracture reduction ages 6-11, 7 for fracture reduction ages 12-17, 3 for abscess drainage ages 2-5 and 2 for abscess drainage ages 6-11. These are group-level registry counts, not comparative estimates.
The serious-event entries should be read as no serious adverse events recorded among the participants listed as at risk in each of these groups. They do not establish that serious events are impossible or that the treatment is safer than an alternative. Because the study has no control group, the listed counts cannot provide a like-for-like comparison with another treatment. The record does not provide a definition of the “other” event category in the details, so those counts should not be assigned a more specific clinical meaning.
The adverse-event listing does not include every age-and-procedure combination described for the primary endpoint. The registry does not explain this coverage or how the entries relate to overall enrollment. The record also does not report event timing, duration, severity grading for other events, or completeness of safety follow-up. These limitations matter when interpreting counts as a description of reported events rather than as a comprehensive comparison of safety.
12. What the Result Does, and Does Not, Mean
The registry record describes an investigation of rapidly administered ketamine dose levels associated with effective sedation during pediatric abscess drainage and fracture reduction. It defines ED50 and ED95 as the primary measures and identifies age and procedure as the intended bases for separate estimates. This establishes the question the study set out to address.
The record does not report the actual ED50 or ED95 values, confidence intervals, or response data. It therefore does not show which dose estimates resulted or how precisely they were estimated. The endpoint’s target response proportions are definitions, not observed study results. The secondary outcome names likewise do not establish how often vomiting occurred or how many participants met the Wisconsin Sedation Scale threshold.
The design is single-group and has no control or comparison group. Accordingly, the registered information cannot establish whether ketamine is better or worse than another sedation approach, or whether any observed outcome was caused by the intervention. The record’s safety counts describe listed events in the listed groups; they do not provide a controlled safety comparison.
The enrollment information also needs to be read without attempting to reconcile it: the registry lists enrollment as 111, while the primary outcome description says 100 children were enrolled in 5 groups. The relationship between these entries is not reported in the registry record. That uncertainty, along with unreported analysis methods and missing-data handling, limits assessment of who contributed to each outcome.
Thus, the posted information supports a careful account of the trial’s purpose, registered design and outcome definitions, but not a conclusion about a particular effective dose or comparative treatment performance. Results absent from the registry should be understood as not reported in the registry record, rather than interpreted as no effect or no events.
13. Why This Trial Matters Statistically
This study raises a useful statistical problem: estimating a dose associated with a target probability of response is not the same task as testing whether one treatment differs from another. The ED50 and ED95 definitions focus on the dose-response relationship, while the single-group design means there is no randomized comparator. Keeping those questions separate helps prevent dose estimates from being misread as evidence of comparative benefit.
The planned separation by age and procedure also highlights the value and cost of subgroup estimation. Tailoring estimates to distinct groups can make results more relevant to the populations and procedures under study, but each estimate depends on the information available in that subgroup. As a general matter, subgroup estimates may have greater uncertainty when based on less data. The registry does not report the estimates or their precision, so this issue cannot be evaluated for the study’s actual results.
The record also illustrates why outcome definitions are not enough for statistical interpretation. It specifies the primary measures and lists secondary outcomes, but the analysis model, uncertainty intervals, missing-data methods and multiplicity approach are not reported. Without those details and the numerical findings, readers can understand the study’s intended question but cannot assess the robustness of its answers.
Finally, the discrepancy between the enrollment field and the primary outcome description underscores the importance of clear accounting of analyzed populations. The record reports enrollment as 111 and separately says 100 children were enrolled in 5 groups; it does not explain the relationship. Transparent participant flow and analysis-population definitions would help readers understand how enrolled participants contributed to dose and safety summaries.
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.
Several limitations specific to this record constrain interpretation. The primary endpoint is defined in detail, but its ED50 and ED95 estimates, response data and uncertainty measures are not reported in the registry record. Without those results, the main dose-estimation question cannot be answered from the posted information.
The study is single-group, with no control or comparison group and no masking. It can therefore not provide a randomized comparison with another sedation strategy. The record does not report the dose-assignment procedure, the definition or assessment criteria for effective sedation beyond the endpoint description, or the statistical model used to estimate dose-response thresholds.
Enrollment is reported as 111, while the primary outcome description refers to 100 children in 5 groups. The relationship between these statements is not reported in the registry record. The adverse-event information lists five age-and-procedure groups, which do not cover every age and procedure combination specified for the primary endpoint; the record does not explain why or how those safety groups relate to the primary analysis.
The registry does not report a statistical analysis plan, sample-size justification, missing-data approach, analysis populations, multiplicity strategy, confidence intervals or sensitivity analyses. Although planning assumptions are described as an illustration based on an observed effect, the resulting planning values are not reported in the registry record. These planning assumptions are not evidence of observed power or a description of the trial’s own design.
The safety entries provide group counts, but definitions and follow-up details for the other reported events are not reported in the registry record. These limitations mean that neither the primary dose estimates nor a full comparative safety interpretation can be reconstructed from the registered details.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study to Find the Dose of Rapidly Administered Ketamine for Brief Painful Procedures in Children — NCT01669642.
- Registry record last updated 2019-04-25; status last verified 2019-04.
- Results first posted 2018-03-12.
- 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 identifies a completed, single-group study of rapidly administered ketamine for pediatric abscess drainage and fracture reduction. Its primary outcome is the median effective dose, including ED50 and ED95, measured in mg/kg during the timeframe from dose administration through 5 minutes. Estimates were intended for age groups 2-5, 6-11 and 12-17 and for both procedures.
The record lists enrollment as 111; the primary outcome description separately refers to 100 children in 5 groups. The relationship is not reported in the registry record. The design has no control or comparison group and no masking. The record lists vomiting and a Wisconsin Sedation Scale score outcome as secondary measures, but their results are not reported in the registry record.
Primary dose estimates, confidence intervals, analysis methods, missing-data handling and multiplicity plans are not reported in the registry record. The listed safety groups record zero serious adverse events and zero deaths in each group, alongside group-specific counts for other events. These figures are descriptive and do not constitute a controlled safety comparison.