Comparison of Patient Centered Outcomes for People With Sickle Cell Disease in the Acute Care Setting: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Patient Centered Outcomes for People With Sickle Cell Disease in the Acute Care Setting (NCT02411396), a registered phase not stated study. The primary outcome is Time (Minutes) From Arrival to Center to Time First Dose of Parenteral Pain Medication Administered.

2. Clinical Question

The study’s stated purpose is to compare patient-centered outcomes for patients with sickle cell disease receiving care for uncomplicated vaso-occlusive crisis in infusion centers and emergency departments. The primary endpoint is a time measure, while the listed secondary outcomes concern disposition, timely pain reassessment, satisfaction with care, and perceived risk from the visit. Together, these outcomes cover care processes and patient-reported experience as well as the endpoint’s medication-timing focus.

The registry record does not report the primary endpoint’s numerical results, setting-specific estimates, or a statistical comparison between settings. It therefore does not establish from the posted information whether the observed time differed between the settings or how precisely any difference was estimated. The study question is clear, but answering it quantitatively requires outcome results that are not reported in the registry record.

3. Trial Design

The registry lists the study as completed and reports enrollment of 483. The study concerns people with sickle cell disease and compares patient-centered outcomes for uncomplicated vaso-occlusive crisis care in infusion centers and emergency departments. Its description places the comparison in four locations around the United States. The sponsor is Johns Hopkins University. The registry reports a start of 2015-04 and primary completion of 2018-06.

The record describes one group, “Patients With SCD,” as patients treated for uncomplicated vaso-occlusive crisis in infusion centers and emergency departments. It does not report separate arm descriptions that would establish a randomized, like-for-like comparison. The allocation is not stated, and the registry information identifies the study as not a randomized comparison. This means the setting comparison should not be interpreted as though participants were assigned at random to otherwise interchangeable groups.

The primary outcome is the time from arrival at the center to administration of the first parenteral pain medication dose, with a timeframe of within 6 hours after arrival. The registry lists five outcome measures and three analyses. Secondary outcomes include disposition from the acute care visit, pain reassessment within 30 minutes of the first parenteral pain medication dose, patient-reported satisfaction with care, and patient-reported perception of risk from the visit.

Some enrolled participants did not visit an emergency department or infusion center for uncomplicated vaso-occlusive crisis. Also, one participant could contribute multiple visits, so the total number of subjects analyzed can exceed the total number of subjects. The record does not report the statistical plan, enrollment targets by setting, or the number of visits contributing to each outcome.

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: Not all participants enrolled in the study visited the ED or the IC for uncomplicated vaso-occlusive crisis. The total number of subjects analyzed exceeds the total number of subjects because the same subject could visit the ED or IC one or more times.

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 Time (Minutes) From Arrival to Center to Time First Dose of Parenteral Pain Medication Administered, measured over Within 6 hours after arrival.

The primary endpoint measures elapsed time, in minutes, from a patient’s arrival at an emergency department or infusion center for pain treatment to the first parenteral pain medication dose. The registry sets the measurement timeframe as within 6 hours after arrival. This is a continuous measure: each qualifying visit can have a time value, and the registry identifies the intended summary as a mean with a 95% confidence interval.

This endpoint is used to describe a care process that is directly relevant to the timing of acute pain treatment. The registry’s endpoint description states that guideline recommendations are for patients to receive non-oral pain medication within 60 minutes of arrival. That recommendation provides context for why time to first dose is measured; it does not itself describe the study’s observed results or show whether care met the recommendation.

Repeated visits matter for interpreting the endpoint. The registry notes that the same participant could visit an emergency department or infusion center one or more times, and that the number of subjects analyzed may therefore exceed the number of subjects. Visit-level observations from one person may be related rather than independent. The record does not report how that feature was handled in the analysis.

Numerical mean times, confidence intervals, and setting-specific results for the primary endpoint are not reported in the registry record. Without those results, the direction, size, and precision of any setting difference cannot be described.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary measure as a continuous outcome summarized by a mean and 95% confidence interval. The record does not report the detailed analysis method used to produce the posted results, and it does not report numerical results for the primary measure. The concepts below explain how such summaries are generally interpreted; they are not a claim about procedures used in this study.

What does a mean describe?

In general, a mean summarizes the values observed across the analyzed observations by representing their central average. For a time endpoint, the mean describes the average recorded elapsed time in the analysis population. It does not show how values are distributed around that average. Visits can have shorter or longer times, and the mean alone does not reveal the range, shape, or concentration of those times.

In this study, the registry says participants could contribute more than one visit. If each visit is treated as an observation, visits from the same participant may share characteristics and may not be statistically independent. General statistical methods for repeated observations can account for such within-person dependence. The registry record does not report whether the analysis used such a method, or whether the outcome was summarized per visit or per participant.

How should a confidence interval be read?

In general, a confidence interval describes uncertainty around an estimate under the assumptions of the method used to calculate it. A 95% confidence interval gives a range of values compatible with the data and analysis method at the stated confidence level. It is not a range containing 95% of individual visit times, and it does not mean there is a 95% probability that a fixed parameter lies within one particular calculated interval.

For a comparison, the confidence interval around an estimated difference would help show the precision of that difference. A narrow interval generally indicates greater precision than a wide one, while the interval’s location relative to no difference helps assess compatibility with different possible effects. No setting-specific means, estimated difference, or confidence intervals are reported in the registry record, so these interpretations cannot be applied to the study’s actual result.

Why can over-dispersion matter?

In general, over-dispersion means the observed variability is greater than a statistical model expects. If a method assumes less variability than is present, uncertainty can be understated. This concept is particularly relevant to count outcomes; the primary endpoint is continuous time, and the registry record does not state that over-dispersion was assessed or was present. More broadly, model assumptions about the distribution of times and dependence among visits affect standard errors and confidence intervals. The registry record does not describe those assumptions.

What does the planning illustration represent?

The registry information describes a sample-size planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration considers a stated fraction of the observed effect. It is a planning exercise, not observed power and not evidence that the original study was designed with those assumptions. The record does not report the study’s own sample-size justification or design assumptions. Numerical planning results are not reported in the registry record.

In general, a planning calculation estimates the sample size that might be needed under specified assumptions. Its result depends on the assumed effect size, variability, significance threshold, allocation, and analysis method. If an assumed effect is based on an observed estimate, the planning result inherits uncertainty in that estimate. Such calculations should not be read as a measure of the probability that the completed study found a true effect. The registry does not report the assumptions used in the original study design.

What can the listed analysis count tell us?

The registry lists three analyses, but does not describe their models, contrasts, covariate adjustments, or relation to the five outcome measures. A count of analyses does not reveal which results were prespecified, whether all planned analyses were reported, or how repeated visits were handled. Those details are not reported in the registry record. Without them, it is not possible to evaluate the suitability of a specific statistical model or reproduce an estimate.

General interpretation should distinguish statistical precision from practical importance. A confidence interval can describe uncertainty, while clinical and operational context is needed to assess what a time difference would mean. The endpoint’s guideline context is included in its description, but the registry record does not report the estimates needed to judge the observed timing against that context.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures and three analyses. The primary measure concerns time to the first parenteral pain medication dose; the listed secondary outcomes concern disposition, pain reassessment, satisfaction, and perceived risk. Considering multiple outcomes or analyses can increase the chance that at least one result appears noteworthy by chance. In general, a prespecified hierarchy or multiplicity adjustment can help define how results should be interpreted when several statistical tests are conducted. The registry record does not report whether such a strategy was used, which outcomes were designated for formal testing, or how the analyses were prioritized.

The registry record does not report a missing-data plan, the extent of missing outcome data, or how missing observations were handled. It also does not describe the analysis populations for the primary or secondary outcomes. These details matter because participants enrolled in the study were not all reported to have visited an emergency department or infusion center for uncomplicated vaso-occlusive crisis. The number contributing data to a particular outcome may therefore differ from total enrollment, but those outcome-specific counts are not reported in the registry record.

Repeated visits create another analysis-population issue. The same participant could visit a setting more than once, and the record notes that the number of subjects analyzed may exceed the number of subjects. The registry record does not state whether observations were analyzed as independent visits, whether within-participant dependence was modeled, or whether any approach was used to select visits for analysis.

Allocation is not stated, and the comparison is not randomized. The registry record does not report how differences in participant or visit characteristics between settings were addressed. It also does not report interim analyses, stopping rules, or the detailed statistical analysis plan. These omissions limit assessment of selection, analysis choices, and the scope of conclusions that can be drawn from the posted results.

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

The study addresses an important statistical question about the timing of parenteral pain medication during acute care for uncomplicated vaso-occlusive crisis in people with sickle cell disease. The primary endpoint is clearly described as elapsed time from arrival to the first dose, with the mean and 95% confidence interval identified as the intended summary. The registry also gives a guideline context for why this timing is relevant.

What the registry record does not report is the numerical primary result, the estimates for each care setting, or a statistical contrast between those settings. It also does not report numerical findings for the listed secondary outcomes. Consequently, the posted information does not show how long patients waited on average, how variable those times were, whether the settings differed, or how precise an estimated difference might be.

Even if an association between setting and an outcome were reported, the nonrandomized comparison and unstated allocation would limit causal interpretation. Differences between settings could reflect differences in the patients or visits represented in each setting, as well as care processes. The record does not report sufficient details to separate these explanations. The results should not be interpreted as showing that a setting caused a particular outcome.

The registry’s note about repeat visits also means that enrollment is not necessarily the same as the number of outcome observations or unique participants analyzed. The number of visits and the handling of within-person dependence are not reported. These details would be needed to understand the precision of the analysis and the population to which an estimate applies.

The adverse-event summary lists 10 deaths, alongside zero counts in the reported serious-event and other-event at-risk and affected fields. The record does not provide context about timing, cause, relation to the study, or setting. These entries cannot establish a causal relationship or support a comparative safety conclusion.

Overall, the registry record describes the question and endpoint, but does not report the numerical results and analysis details needed to determine what the observed data show about differences between settings.

12. Why This Trial Matters Statistically

This study’s statistical question connects an operational measure of acute care with patient-centered outcomes. Time from arrival to first parenteral pain medication dose is measurable across visits and has a stated guideline context. The accompanying outcomes broaden the focus to disposition, reassessment, satisfaction, and perceived risk. Together, these measures illustrate how a clinical comparison can include both care processes and patient experience.

The record also highlights why the unit of analysis matters. Participants could have more than one qualifying visit, and some enrolled participants did not have a visit for the condition described. A visit-based analysis and a participant-based analysis answer different questions. If repeated visits from one person are analyzed, their dependence can affect uncertainty estimates. The registry record does not say how the analysis addressed these issues, making the limitation a useful example of why the analysis population and handling of repeated observations should be reported clearly.

The nonrandomized design is another important statistical feature. A comparison between care settings can describe differences in observed outcomes, but unstated allocation and possible differences among the people or visits in each setting complicate causal interpretation. Clear reporting of setting-specific estimates, uncertainty, adjustment methods, and the factors considered would help readers understand how much of a contrast is attributable to the settings versus the populations receiving care.

Finally, the record separates a clearly described endpoint from results that are not reported. A well-defined measure and a stated benchmark do not, by themselves, establish what happened in the study. Numerical estimates and their precision are necessary for interpreting the observed evidence. This distinction is central to reading registry records: design descriptions identify the question, while outcome results and analysis details are needed to evaluate the answer.

13. 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 primary limitation for interpreting this trial from the registry record is that numerical results for the primary endpoint are not reported in the registry record. Setting-specific means, a contrast between settings, and confidence intervals are also not reported. Without these, the size, direction, and precision of any difference cannot be assessed. Numerical results for the listed secondary outcomes are not reported either.

The comparison is not randomized, and allocation is not stated. The registry record does not report how participants or visits came to receive care in each setting, whether the groups differed at baseline, or how such differences were addressed analytically. This limits causal interpretation of any observed setting contrast. The record does not report the original statistical analysis plan, sample-size justification, or interim analyses.

The registry notes that not all enrolled participants visited an emergency department or infusion center for uncomplicated vaso-occlusive crisis. It also notes that a participant could contribute multiple visits. However, the numbers of qualifying visits and participants contributing to each outcome are not reported in the registry record. The record does not state how repeated visits were handled, whether missing outcomes occurred, or how any missing data were treated.

The listed five outcome measures and three analyses raise questions about the prespecified analysis hierarchy and multiplicity. The registry record does not report whether adjustments were made for multiple outcomes or analyses, or which findings were designated as primary for statistical testing beyond the stated primary outcome.

The adverse-event summary lists 10 deaths but does not report their timing, cause, relation to the study, or distribution by care setting. Those details are necessary to interpret the entry and cannot be inferred from the summary. Overall, the registry record describes the study question and outcome definitions more fully than its analysis procedures and numerical findings.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Comparison of Patient Centered Outcomes for People With Sickle Cell Disease in the Acute Care Setting — NCT02411396.
• Registry record last updated 2019-06-27; status last verified 2019-06.
• Results first posted 2019-06-17.
• 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.

17. Record Summary

The registry record describes a completed study sponsored by Johns Hopkins University, with enrollment of 483 and a start of 2015-04 and primary completion of 2018-06. It concerns patient-centered outcomes for people with sickle cell disease treated for uncomplicated vaso-occlusive crisis in infusion centers and emergency departments at four locations around the United States.

The primary endpoint is time from arrival at the care center to the first parenteral pain medication dose, within 6 hours after arrival. The registry identifies the mean and 95% confidence interval as the summary. Listed secondary outcomes cover disposition, pain reassessment, satisfaction, and perceived risk. The record notes that some enrolled participants did not make a qualifying visit and that participants could contribute multiple visits.

Allocation is not stated, and the comparison is not randomized. Numerical primary and secondary outcome results, detailed statistical methods, missing-data handling, and multiplicity procedures are not reported in the registry record. The adverse-event summary lists 10 deaths without further context about timing, cause, or relationship to the study.