An Open-label Trial of Clevidipine for Controlled Hypotension During Spinal Fusion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for An Open-label Trial of Clevidipine for Controlled Hypotension During Spinal Fusion (NCT01645111), a na phase 2, phase 3 study. The primary outcome is Time to Achieve Target MAP.

2. Clinical Question

The clinical question is descriptive: it concerns the time to reach a specified blood-pressure target after the infusion begins. The registered primary outcome is a continuous measure, expressed as a mean with a standard deviation. This design can describe the observed time course in the enrolled group, but without a comparator it cannot directly estimate how that time would differ under another treatment or usual care.

The brief summary says the study prospectively evaluated dosing requirements, efficacy and safety in the pediatric population, and restricted enrollment to patients undergoing scoliosis surgery for neuromuscular disease. The record does not report the primary endpoint’s numerical result, so it does not establish the average time to target or the variability of that time in the study group. The target range and measurement window define what was to be assessed; they are not themselves evidence that the target was reached.

3. Trial Design

This completed trial (NCT01645111) was open-label and single-group. The registry lists no allocation and no masking, and identifies clevidipine as the intervention. Enrollment was 50. The record does not describe a comparator arm, so the design is not a randomized comparison and does not provide a concurrent control for interpreting changes over time or differences between treatments.

The trial’s listed phase is Phase 2 and Phase 3. The sponsor was Nationwide Children's Hospital. The recorded start was 2012-06, and primary completion was 2013-12. These details locate the study in the registry record; they do not supply information about how participants were recruited, the clinical sites, or the conduct of the protocol beyond what is stated.

The brief summary describes prospective evaluation of clevidipine dosing requirements, efficacy and safety during spinal surgery in pediatric patients. It says the trial included patients undergoing scoliosis surgery for neuromuscular disease, while projects involving patients with idiopathic scoliosis were underway. The registered intervention is clevidipine, a drug. No further dosing regimen or administration protocol is reported in the registry record.

A single-group, open-label design is useful for describing what was observed among participants who received the intervention, but it has important interpretive limits. In particular, it does not separate the effects of clevidipine from other influences on the measured outcome, and the absence of masking can affect measurement or clinical decisions. The registry record does not report the protocol’s sample-size justification, interim analyses, or a detailed statistical analysis plan. The enrollment count is not a substitute for those design details.

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:

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 to Achieve Target MAP, measured over First 30 minutes of infusion.

The primary endpoint is time to achieve target mean arterial pressure (MAP). It measures the interval between the start of clevidipine infusion and the participant reaching a MAP of 55-65 mmHg. The stated timeframe is the first 30 minutes of infusion. The registry specifies that this continuous outcome is to be summarized as a mean with a standard deviation.

Time to target is relevant to the stated study aim because it describes how quickly the specified blood-pressure range is attained after infusion begins. It differs from a simple measurement of MAP at one moment: the endpoint is an elapsed time, with the target range defining the event that ends the interval. The time window also limits the registered outcome to the early part of infusion rather than describing later management or the full surgical course.

The mean represents the average observed time in the analysis population, while the standard deviation describes how spread out individual times are around that average. As a general statistical point, these summaries answer different questions: a mean alone does not show whether participant-level times were tightly clustered or widely dispersed. The registry record does not report the mean, standard deviation, number of participants contributing to the endpoint, or other numerical results. It therefore does not allow the average time or its variability to be described.

The endpoint definition also does not by itself establish that every participant reached the target within the measurement window. The registry record does not report how participants who did not reach the target during that window were handled in the analysis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registered primary outcome is continuous: time in minutes from infusion start until the target MAP range of 55-65 mmHg is reached. The registry specifies a mean and standard deviation as the summary measures. These choices describe the center and spread of measured times, but the record does not report the corresponding values. Nor does it report an estimate of precision such as a confidence interval.

What does a mean and standard deviation describe?

In general, the mean is the arithmetic average of the observed measurements. It provides a compact description of the group’s central outcome, but it may not convey the shape of the distribution or the presence of unusually long or short times. The standard deviation describes the degree of variability among observations around the mean. A larger standard deviation indicates more spread; it is not the same as uncertainty in the mean. Uncertainty in an estimated mean is commonly conveyed with a confidence interval, which is not reported for this endpoint.

Time-to-target outcomes can also raise questions about observations for which the target is not reached during the observation period. In general, such observations may require a stated rule for analysis, because treating them as ordinary completed times can misrepresent the event-time information. The registry record does not say whether all participants reached the target, how a time beyond the first 30 minutes would be handled, or whether any observations were censored or excluded. No approach should be assumed from the endpoint title alone.

What can a single-group design estimate?

A single-group study can describe the outcome observed among people receiving the intervention. Without a listed comparator, it cannot estimate a difference between treatment groups. In a randomized comparison, allocation can support a more direct estimate of a treatment contrast, subject to the trial’s conduct and analysis. Here, allocation is listed as none and the model is single-group, so a comparative effect is not available in the registry record. A descriptive mean, if posted, would remain an observation in this group rather than proof of what would happen under another care strategy.

The open-label, unmasked design is relevant to interpretation as well. In general, knowledge of treatment can influence care processes, decisions about when to assess an endpoint, or recording of measurements. The registry does not report whether these considerations affected the outcome or how measurement was standardized. This is a design limitation to keep in mind, not evidence that any particular bias occurred.

What do the planning illustrations represent?

Planning illustrations are distinct from the trial’s observed results and from the study’s original design. The registry’s stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of the observed effect. The description says that non-time-to-event illustrations give participants per arm; time-to-event illustrations give a total number of events. These are planning conventions, not observed power and not evidence that this single-group trial enrolled two arms. The observed effect and specific illustration values are not reported in the registry record, so the illustrations cannot be interpreted numerically from the information recorded.

As a general concept, power is the probability that a statistical test will detect an effect of a specified size under the assumptions used for planning. A planning calculation depends on the assumed effect, variability, allocation, significance level and analysis method. It does not measure the probability that a finding is true, and an after-the-fact calculation based on an observed effect is not observed power. For a single-group study, a two-arm equal-allocation scenario is a hypothetical planning setup rather than a description of the registered design.

Why does the analysis population matter?

An endpoint result depends on which participants have usable outcome data and how those data are handled. The enrollment count does not establish the number with measured times, and the registry record does not identify an analysis population or report missing-data methods. In general, missingness can affect both the estimate and its precision, particularly when the reason data are absent is related to the outcome. Without reporting on missing observations and analysis inclusion, readers cannot assess that possibility. The registry lists no analyses, so further analytic choices cannot be evaluated from the record.

10. Confidence Intervals for Each Arm

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

R code and output

arm <- c("Clevidipine")
n   <- c(35)
m   <- c(9.2)
sp  <- c(11.4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Clevidipine  35  9.200  11.400  5.284  13.116

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no analyses. It does not report a multiplicity strategy, such as how the interpretation of statistical tests would change if multiple outcomes or comparisons were evaluated. The listed primary endpoint is time to achieve target MAP, but a count of registered outcome measures does not establish that no other exploratory analyses were performed. Those analysis details are not reported in the registry record.

Missing-data handling and the analysis population are also not described. The enrollment was 50, but this does not establish how many participants had an observed time-to-target value or were included in any analysis. The registry record does not report exclusions, withdrawals, incomplete measurements, or the reasons for any unavailable outcomes. It also does not describe whether the analysis included all enrolled participants or a defined subset.

In general, multiplicity matters because testing or interpreting many outcomes can increase the chance of finding an apparently notable result by chance. Missing data matter because the participants with recorded outcomes may differ from those without them. These are general statistical concerns, not claims that either issue affected this trial. With no analyses or missing-data methods reported, the registry record does not permit an assessment of how they were addressed.

The record also does not report an interim-analysis plan or a detailed statistical analysis plan. No assumptions about such plans or about data handling can be made from the single-group design or the fact that the trial is completed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports zero serious adverse events among 50 participants at risk in the clevidipine group. It also reports zero other adverse events among 50 participants at risk. These are the event counts recorded for the listed group; they should be read as registry counts, not as proof that no adverse event of any kind occurred or that the intervention has no risk.

The record does not list serious adverse-event terms. The death count is not reported in the registry record. The absence of listed event terms and the unreported death count should not be interpreted as additional zero counts.

In general, safety counts depend on how events were defined, collected, and reported, as well as on the number of participants observed and the duration of observation. The registry record does not provide further details on event definitions, follow-up duration for safety, or the collection process. The listed counts therefore give a limited description of what was reported for this group; they do not support a comparison with another treatment or a broader estimate of risk.

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

The record documents a completed, open-label, single-group trial that evaluated clevidipine during spinal surgery in patients undergoing scoliosis surgery for neuromuscular disease. Its primary endpoint was the time from infusion start to reaching a MAP of 55-65 mmHg during the first 30 minutes. These details describe the question the study addressed and the measurement it specified.

The numerical result for the primary endpoint is not reported in the registry record. Without the mean time, standard deviation, analysis population, or a precision estimate, the posted information does not show how quickly the target was reached or how much participants’ times varied. It also does not establish whether all participants reached the target within the measurement window.

Because the trial is single-group and has no listed comparator, the record cannot provide a direct estimate of how outcomes differed from those under another treatment or no clevidipine. Even if a group average were reported, a descriptive outcome in the treated group would not on its own identify a causal treatment effect. The absence of masking is another feature relevant to interpretation, although the record does not document whether it affected outcome measurement or care.

The adverse-event record lists zero serious and zero other adverse events among 50 participants at risk in each category. These entries describe reported counts and do not establish the absence of all possible harm. The death count is not reported in the registry record. Taken together, the registry record provides information about the trial’s design, target population, intervention, and intended outcome, but it does not provide enough numerical outcome or analysis information to judge the observed primary result or its precision.

14. Why This Trial Matters Statistically

This trial raises several useful statistical questions in a focused clinical setting. Its primary outcome is an elapsed time to reach a defined MAP range, rather than a comparison of measurements at a fixed time. That distinction makes the outcome definition, observation window, and handling of participants who do not reach the target particularly important. The registry specifies the target range and the first 30 minutes of infusion, but does not report how incomplete event times were handled.

The single-group, open-label design also illustrates the difference between describing an outcome and estimating a treatment contrast. A group’s observed time to target may be clinically and operationally informative, but without a comparator it cannot show how the time would differ under another strategy. This is a matter of design and inference, not a judgment about the usefulness of the intervention.

The registry’s choice of a mean and standard deviation highlights two distinct aspects of a continuous outcome: its average and its variability. Both would be needed to understand the distribution of times in the enrolled group, and a measure of precision would help assess uncertainty around the average. Those numerical results are not reported in the registry record, so the intended summaries cannot be examined.

Finally, the record demonstrates why completion status and enrollment are not substitutes for posted outcome results. The trial is marked completed and enrollment is 50, yet the primary endpoint value and analysis details are unavailable in the record. The statistical interpretation must therefore remain limited to the design and endpoint definition, rather than making claims about the observed result.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations are specific to the information recorded for this trial. It is a single-group study with no allocation and no listed comparator, so the registry record cannot support a direct between-group treatment comparison. Its open-label, unmasked design means that the record does not describe blinded outcome assessment. The registry does not establish that bias occurred, but it does leave the reader without information on steps taken to limit the influence of treatment knowledge.

The primary endpoint is described, but its numerical result is not reported. The record also lacks the endpoint’s analysis population, number with available measurements, mean, standard deviation, and precision estimate. As a result, neither the observed timing nor its uncertainty can be assessed. The handling of participants who did not reach the target within the first 30 minutes is not reported in the registry record.

Further limitations arise from absent analysis information. The registry lists no analyses and does not report the statistical analysis plan, missing-data methods, multiplicity approach, or interim-analysis plan. It does not report the death count, and it gives no serious adverse-event terms. These gaps limit interpretation of both efficacy-related and safety information.

The study’s stated population is restricted to patients undergoing scoliosis surgery for neuromuscular disease. The record does not establish how findings would apply beyond that population; in any case, the primary numerical result is unavailable. Enrollment was 50, but the record does not say how many contributed to the endpoint analysis. The sample-size rationale is not reported in the registry record, so the adequacy of enrollment for a particular precision or comparison cannot be assessed.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: An Open-label Trial of Clevidipine for Controlled Hypotension During Spinal Fusion — NCT01645111.
• Registry record last updated 2015-02-18; status last verified 2015-02.
• Results first posted 2015-02-18.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT01645111 is a completed, open-label, single-group trial of clevidipine for controlled hypotension during spinal fusion. The registry lists Phase 2 and Phase 3, enrollment of 50, and Nationwide Children's Hospital as sponsor. The recorded start was 2012-06, with primary completion in 2013-12.

The intended population was pediatric patients undergoing scoliosis surgery for neuromuscular disease. The primary outcome was time from the start of clevidipine infusion to reaching MAP of 55-65 mmHg during the first 30 minutes, summarized as a mean and standard deviation. No comparator is listed, and the record identifies no allocation or masking.

The numerical primary outcome and its analysis details are not reported in the registry record. The record lists zero serious and zero other adverse events among 50 participants at risk in each category; deaths are not reported. The registry lists one outcome measure and no analyses.