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 Use of an Oral Beta-2 Agonist in Persons With Spinal Cord Injury (NCT00755079), a randomized phase 2, phase 3 study. The primary outcome is Inspiratory Respiratory Muscle Strength.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00755079 |
| Phase | Phase 2, Phase 3 |
| Condition | Spinal Cord Injury |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 40 |
| Arms in the primary outcome | n/a |
| Lead sponsor | US Department of Veterans Affairs |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with spinal cord injury, with the summary specifying cervical and high thoracic injuries. The record does not report additional eligibility criteria or a fuller description of the enrolled population.
Intervention
Participants assigned to active treatment received an oral beta-2 adrenergic agonist. The study summary identifies the drug as albuterol, taken at 4 mg twice daily during 12 weeks of intervention.
Comparator
The comparison group received a blinded placebo capsule. The trial was randomized, placebo-controlled, and parallel-group; the study summary says investigators and participants were blinded to the allocation.
Primary question
The primary question was whether inspiratory respiratory muscle strength, measured by maximal inspiratory pressure at the mouth, differed in relation to active treatment compared with placebo. Measurements were planned at baseline and after 12 weeks.
3. Trial Design
This was a randomized, triple-masked, parallel-group trial with placebo control. The registry lists the study as Phase 2 and Phase 3 and as completed. The sponsor was the US Department of Veterans Affairs. Enrollment was 40. The record gives a start date of 2007-04 and a primary completion date of 2012-08.
The study summary describes a 12-week intervention in which participants were randomized to oral albuterol or placebo. The active treatment is described as an oral beta-2 adrenergic agonist, and the summary identifies albuterol at 4 mg twice daily. The placebo group received a blinded capsule. Although the record labels masking as triple, the summary specifically states that investigators and participants were blinded by the research pharmacy; the identity of any additional masked role is not reported in the registry record.
The primary outcome was inspiratory respiratory muscle strength, measured at baseline and after 12 weeks. Expiratory respiratory muscle strength was listed as a secondary outcome. The registry record does not describe the randomization procedure, allocation concealment, treatment adherence, or how participants were assigned to the analysis populations. It also does not report a primary-outcome estimate or an analysis comparing the groups. Consequently, the design can be described, but the treatment contrast in the primary outcome cannot be evaluated from the posted results.
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 | Placebo Control | Active Drug |
|---|---|---|
| STARTED | 18 | 22 |
| COMPLETED | 17 | 16 |
| NOT COMPLETED | 1 | 6 |
Reasons for not completing this period:
| Reason | Placebo Control | Active Drug |
|---|---|---|
| Lost to Follow-up | 1 | 3 |
| Adverse Event | 0 | 1 |
| Withdrawal by Subject | 0 | 2 |
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 | Placebo | Active Drug | Total |
|---|---|---|---|---|
| Participants analysed | 17 | 16 | 33 | |
| Age, Continuous | years | 42.24 (SD 9.53) | 42.75 (SD 14.74) | 42.48 (SD 12.14) |
| Sex: Female, Male: Female | Participants | 1 | 1 | 2 |
| Sex: Female, Male: Male | Participants | 16 | 15 | 31 |
| Region of Enrollment: United States | participants | 17 | 16 | 33 |
6. Primary Endpoint
The registry lists the primary outcome as Inspiratory Respiratory Muscle Strength, measured over Outcome will be measured at baseline, prior to intervention, and after 12 weeks of twice daily drug treatment..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | cmH2O |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was inspiratory respiratory muscle strength. The registry describes it as measured using maximal inspiratory pressure at the mouth and gives the unit as cmH2O. It identifies the outcome as a continuous measure summarized by a mean and standard deviation. The planned measurement times were before intervention and after 12 weeks of twice-daily treatment.
In general, a continuous physiological measurement can retain more information than a simple category such as improved or not improved, because it records the measured value across a range. A baseline measurement also helps describe the participants before treatment begins. A comparison of measurements after treatment may be interpreted differently depending on whether it uses the final value, change from baseline, or an adjustment for baseline. The registry record does not report which comparison or statistical model was planned or used.
Respiratory muscle strength was selected because the study’s stated purpose was to assess the effect of the intervention on that function in people with spinal cord injury. The record also lists expiratory respiratory muscle strength as a secondary outcome. It does not provide endpoint values, a group contrast, uncertainty estimates, or a definition of a clinically important difference. The endpoint description therefore identifies what was measured, but does not establish the size or precision of any treatment-related difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes that this was a randomized comparison of oral albuterol and placebo for respiratory muscle strength in people with spinal cord injury. It describes a planned 12-week treatment period and measurement of inspiratory strength before intervention and after treatment. Those design details do not, by themselves, indicate what the comparison found.
No numerical result for the primary endpoint is reported in the registry record. There is no posted group mean, standard deviation, treatment contrast, confidence interval, or p-value for inspiratory respiratory muscle strength. The record also lists zero analyses. As a result, the direction, magnitude, and statistical precision of the primary comparison cannot be determined from these registry entries. The trial should not be described as showing either a benefit or no difference on the primary outcome.
The endpoint description notes that the outcome was measured at baseline and after 12 weeks, but a set of measurement times is not itself a treatment-effect estimate. A meaningful comparison would need to state how the two groups were compared, such as whether the analysis used final measurements or change from baseline, and provide an estimate with its uncertainty. Those analysis details and results are not reported in the registry record.
The safety entries are separate from the primary efficacy outcome. They record one serious adverse event among 22 participants at risk in the active-drug group and none among 18 at risk in the placebo group. Other adverse events are recorded as zero in both groups. These counts do not supply evidence about the primary respiratory-strength comparison. Nor do they establish the full safety profile: the registry record does not report deaths, and the counts alone do not describe the nature, timing, or duration of follow-up for every possible event.
In general, statistical significance and clinical importance are different questions. A p-value addresses compatibility of data with a specified statistical model and null hypothesis; it does not state the probability that a treatment works. A confidence interval describes uncertainty around an estimated contrast, given the analysis assumptions. Neither measure is posted for the primary endpoint in this record. Without an estimate and uncertainty interval, readers cannot assess whether the data are compatible with small or large differences, or how precisely the effect was measured.
The record’s completion status indicates that the study is listed as completed, but completion does not substitute for reporting outcome results. The available information supports a description of the study question, design, and recorded safety counts. It does not support a conclusion about the observed primary-outcome effect.
9. Statistical Methods Explained
What does a mean and standard deviation describe?
The primary outcome is identified as a continuous measure summarized by a mean and standard deviation. In general, the mean describes the central value of a set of measurements, while the standard deviation describes how spread out those measurements are around the mean. These are descriptive quantities. A mean for one group, by itself, does not show the difference between randomized groups, and the standard deviation is not the uncertainty interval for that difference.
To estimate a treatment contrast, an analysis must specify which measurements are being compared and how the groups are handled. For a baseline-and-follow-up outcome, an analysis might compare follow-up values, compare changes from baseline, or model follow-up values while accounting for baseline. These approaches can produce different estimates and have different assumptions. The registry record does not report which approach was used or planned. No primary group means, standard deviations, or contrast are posted, so a numerical comparison cannot be reconstructed from the registry record.
What would a confidence interval add?
In general, a confidence interval gives a range of effect estimates compatible with the observed data under the statistical method and its assumptions. It communicates precision as well as direction and magnitude. A narrow interval indicates greater precision than a wide interval, but interpretation also depends on the outcome scale and the range of differences that would matter scientifically. A confidence interval is not a guarantee that the true effect lies in that particular interval, nor does it address bias from missing data, measurement problems, or study conduct.
No confidence interval for the primary outcome is reported in the registry record. A p-value is also not reported. Without these, the primary result cannot be characterized by either its estimated magnitude or the uncertainty around it. The absence of a posted p-value is not evidence that the result was statistically significant or non-significant.
How should the planning illustration be understood?
The registry record 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. The illustrations are described as detecting a stated fraction of the observed effect. They are planning exercises, not the trial’s own design justification and not observed power. The registry record does not report the trial’s sample-size justification.
In general, a sample-size calculation estimates how many participants would be needed under specified assumptions about the effect, variability, allocation, and statistical test. It does not show what effect the trial actually found. A calculation based on an observed effect can be especially dependent on that estimate: if the observed estimate is unstable, planning values derived from it will also be uncertain. The numerical planning outputs and the underlying primary-outcome estimate are not reported in the registry record, so no particular required sample size can be interpreted.
Over-dispersion is a general concern when variation is greater than a statistical model assumes. If the analysis understates variability, uncertainty can appear smaller than it is, affecting confidence intervals and tests. The registry record does not report an over-dispersion assessment or a model that would allow readers to evaluate this issue. It would be inappropriate to assume that over-dispersion was present or absent.
What does randomization contribute?
In general, random allocation is intended to make treatment groups comparable at the start of a trial, on average, including for factors that are measured and those that are not. It does not guarantee identical groups, particularly in a study with limited enrollment. A randomized design supports interpretation of a between-group contrast when allocation is maintained and the analysis is appropriate. The record states that assignment was randomized but does not report the sequence-generation method, concealment details, or baseline outcome values.
Masking can reduce the risk that knowledge of treatment assignment influences care, measurement, or reporting. The record labels the trial triple-masked and the summary says participants and investigators were blinded by the research pharmacy. The registry record does not identify the additional masked role or report whether masking was assessed. These omissions do not establish that masking failed; they limit what can be determined about its implementation.
What can the posted statistical information establish?
The record lists two outcome measures and zero analyses. The primary outcome includes measurements at baseline and after 12 weeks, but the record does not reduce those measurements to a single reported comparison. It does not provide a model specification, an analysis population, a missing-data method, or adjustments for multiple outcomes or time points. These details matter because analytic choices affect how a treatment estimate is defined and how uncertainty is calculated.
General statistical interpretation depends on both the numerical result and the methods used to obtain it. A complete report would ordinarily identify the analysis contrast, estimate, uncertainty, and the participants included. These elements are not reported in the registry record. The posted information therefore supports discussion of the design and endpoint, but not independent evaluation of the primary treatment-effect analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists inspiratory respiratory muscle strength as the primary outcome and expiratory respiratory muscle strength as a secondary outcome. The primary endpoint was measured at baseline and after 12 weeks. The record does not report how multiple outcomes or measurement times were handled in the statistical analysis, or whether any adjustment for multiple comparisons was planned or used. It also does not identify a single reported follow-up contrast.
In general, multiplicity arises when several outcomes, time points, or statistical tests are examined. With more opportunities to test a hypothesis, the chance of at least one apparently notable result can increase if the analyses are treated as independent confirmatory tests. Prespecifying a primary outcome and a principal comparison can help clarify which test is central; adjustment methods may also be used, depending on the study aims. The registry’s primary and secondary outcome labels do not, by themselves, establish how multiplicity was addressed.
The registry record does not report missing-data counts for the primary outcome, reasons for missing measurements, or an imputation or sensitivity-analysis approach. It does not state whether all randomized participants were included in the primary analysis, whether the analysis followed assigned treatment, or whether another analysis population was used. These are not reported in the registry record. Without these details, readers cannot assess how incomplete outcome measurements or exclusions may have affected the estimate.
In general, missingness can influence results when participants with observed measurements differ from those whose outcomes are unavailable. The direction and size of any resulting bias depend on why data are missing and on the analysis assumptions. No particular missing-data pattern or bias can be inferred for this trial from the posted information.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Placebo | 0 | 18 | 0.0% |
| Active Drug | 1 | 22 | 4.5% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo | 0 of 18 |
| Active Drug | 0 of 22 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | Active Drug |
|---|---|---|---|
| Muscle Cramping | Musculoskeletal and connective tissue disorders | 0 of 18 | 1 of 22 |
Serious events with the highest arm-level rate: muscle cramping (4.5%).
The registry records serious adverse events for 18 participants at risk in the placebo group and 22 in the active-drug group. It records zero serious adverse events in the placebo group and one in the active-drug group. Other adverse events are recorded as zero in both groups. These are counts within the reported at-risk groups, not results for the primary respiratory-strength endpoint.
The record lists muscle cramping as a top serious term with 4.5%. It does not provide a group-specific count for that term in the listing. The registry record does not report deaths; the death entries are null, which is different from a reported count of zero. The serious-event count should therefore not be used to infer that no deaths occurred.
In general, adverse-event counts need context: definitions, event timing, duration of observation, and how events were collected all affect interpretation. A small number of recorded events cannot establish that an event is caused by treatment, and a zero count does not prove that an event cannot occur. The registry entries give limited event-count information; further detail on event descriptions, severity, relatedness, and follow-up is not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The central result that would answer the trial’s stated question is a comparison of inspiratory respiratory muscle strength between the albuterol and placebo groups. The registry record describes the endpoint and its measurement schedule, but does not report the group results or an estimated treatment contrast. Therefore, the posted information does not establish whether the measured outcome differed between groups, the direction of any difference, or its magnitude.
It also does not establish that the groups were equivalent. In general, failure to report a statistically significant difference is not the same as evidence of no meaningful difference. An equivalence or non-inferiority conclusion requires a prespecified margin and an analysis designed for that question. Neither is reported in the registry record. Because no primary estimate or uncertainty interval is posted, the precision of the comparison cannot be judged.
The trial record does support several factual statements: the study was randomized, placebo-controlled, parallel-group, and listed as triple-masked; its stated primary outcome was inspiratory respiratory muscle strength; and the intervention period was 12 weeks. It also records the serious and other adverse-event counts described separately. These design and safety details should not be substituted for an efficacy result.
In general, a study result applies most directly to the population and conditions actually studied. The summary identifies people with cervical and high thoracic spinal cord injury, but the registry record does not provide a fuller account of eligibility, participant characteristics, or treatment adherence. Even if a primary estimate were available, those details would help determine how broadly it could be interpreted. On the current record, no conclusion about treatment effect, clinical importance, or generalizability can be drawn from the primary outcome.
13. Why This Trial Matters Statistically
This trial is statistically notable because its registry record contains a clear randomized, placebo-controlled design and a defined continuous primary outcome, but no posted primary-outcome analysis. The distinction between a study question and a reported estimate is important: design details describe how a comparison was intended to be made, while an estimate and its uncertainty show what the observed data indicate.
Baseline and follow-up measurements create analytic choices. A report needs to define whether the main contrast concerns follow-up values, change from baseline, or another model-based comparison. That choice affects the meaning of the result and can affect precision. The registry record gives the measurement times but does not identify the analysis approach. Readers therefore cannot reconstruct or critically assess the primary contrast.
The record also illustrates why outcome and analysis reporting are distinct. It lists a primary outcome and a secondary outcome, but lists zero analyses. The existence of outcome definitions does not mean numerical results are available, and a completed status does not fill that gap. Without effect estimates and uncertainty, readers cannot distinguish an imprecise result from a precise estimate close to no difference or from a potentially important contrast.
Finally, safety counts and efficacy results answer different questions. The adverse-event entries provide limited event counts, while the primary endpoint concerns respiratory muscle strength. Keeping those evidence streams separate prevents safety observations from being mistaken for a treatment-effect estimate. The record supports understanding of the trial’s structure, but not a statistical conclusion about its primary question.
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.
A major limitation of the available record is the absence of numerical primary-outcome results. Group-level values, a between-group contrast, a standard error or confidence interval, and a p-value are not reported in the registry record. Without them, neither effect magnitude nor precision can be evaluated. The registry also does not report the statistical model, the estimand, or whether the analysis compared follow-up values or change from baseline.
The study summary describes a 12-week intervention, but the record does not report adherence, discontinuations, treatment changes, or the number of participants with measured primary outcomes at each time. It does not report baseline characteristics or baseline respiratory-strength values. The listed enrollment and safety denominators do not resolve these gaps in the primary-outcome data.
The record does not describe the randomization method or allocation concealment, and it does not identify all roles covered by the triple-masking label. These omissions limit assessment of trial conduct but do not demonstrate that randomization or masking was inadequate. The criteria used to define serious events, event follow-up duration, and detailed group-level event descriptions are also not reported in the registry record.
Finally, the record does not provide a sample-size justification, a missing-data plan, an analysis-population definition, or a multiplicity strategy. These limitations are specific to the information available in the registry record; they do not establish what may have been documented elsewhere. They mean that the posted entries alone are insufficient for a full assessment of the planned and completed statistical analysis.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Use of an Oral Beta-2 Agonist in Persons With Spinal Cord Injury — NCT00755079.
- Registry record last updated 2015-03-17; status last verified 2015-02.
- Results first posted 2014-07-16.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes a completed randomized, triple-masked, parallel-group, placebo-controlled trial sponsored by the US Department of Veterans Affairs. It lists Phase 2 and Phase 3, enrollment of 40, a start date of 2007-04, and a primary completion date of 2012-08. The study concerned oral albuterol in people with spinal cord injury, with a 12-week twice-daily intervention described in the summary.
Inspiratory respiratory muscle strength, measured by maximal inspiratory pressure at the mouth, was the primary outcome; expiratory respiratory muscle strength was secondary. The primary outcome was scheduled for measurement at baseline and after 12 weeks. The registry record does not report a primary-outcome comparison or analyses. It records one serious adverse event in the active-drug group and none in the placebo group, with no deaths reported as a numeric count.