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 Research in Severe Asthma (RISA) Trial (NCT00214539), a randomized na study. The primary outcome is Respiratory Adverse Events Per Subject.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00214539 |
| Phase | NA |
| Condition | Asthma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 34 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Boston Scientific Corporation |
| Results posted | Yes |
2. Clinical Question
Population
People with severe asthma refractory to standard medication therapy. The registry record does not provide further eligibility details or a description of the primary-outcome population.
Intervention
Bronchial thermoplasty with the Alair System, alongside standard-of-care therapy with high-dose inhaled corticosteroids and long-acting beta-agonists, with or without oral corticosteroids at a dose no greater than 30 mg/day.
Comparator
Standard-of-care therapy with high-dose inhaled corticosteroids and long-acting beta-agonists, with or without oral corticosteroids at a dose no greater than 30 mg/day.
Primary question
How many respiratory adverse events per subject were reported in the Alair and control groups during the treatment and post-treatment periods? The registry specifies the measure and time periods but says statistics were not calculated.
The study was framed as a randomized comparison of adding Alair treatment to medical management versus medical management alone for severe asthma that remained refractory to standard medication therapy. Its primary endpoint is a count expressed per subject, rather than a conventional clinical response such as change in lung function or symptom score. The registry describes respiratory adverse events during the Treatment Period and the post-treatment Steroid Stable Phase and Steroid Wean and Reduced Steroid Phase.
This question focuses on the recorded frequency of respiratory adverse events in the two groups. It is not, by itself, a complete comparison of safety or efficacy: the registry does not report an inferential analysis of the primary measure, and the primary-outcome description says statistics were not calculated. The secondary outcomes listed include medication use, symptom score, lung function, asthma control, and quality of life, all described as changes from baseline. Their results and analyses are not reported in the registry record.
3. Trial Design
The RISA Trial is listed as a completed, randomized, parallel-group clinical trial sponsored by Boston Scientific Corporation. The registry records an enrollment of 34. Its brief summary describes a plan to randomize 30 subjects in a 1:1 ratio, with one group receiving Alair treatment plus medical management and the other receiving medical management alone. The registry does not explain the difference between the enrollment figure and the planned number in the brief summary.
The trial is described as multicenter. Masking is recorded as none, so the registry characterizes the study as unmasked. This matters when interpreting outcomes that may be influenced by participant or investigator awareness of treatment assignment; the record does not state whether any outcome assessors were masked. Allocation is recorded as randomized, but details about sequence generation, concealment, or implementation are not reported in the registry record.
The treatment group received bronchial thermoplasty with the Alair System in addition to standard-of-care therapy. Standard care consisted of high-dose inhaled corticosteroids and long-acting beta-agonists, with or without oral corticosteroids at a dose no greater than 30 mg/day. The control group received standard-of-care therapy without Alair treatment. The primary-outcome timeframe is listed as Baseline, 12 Months, with respiratory adverse events described across the Treatment Period and two post-treatment phases.
The registry gives a start date of 2004-04 and a primary completion date of 2006-02. It does not report the protocol, detailed visit schedule, treatment adherence, participant flow, reasons for withdrawal, or the number analyzed for each outcome. The phase is listed as NA. The trial’s named secondary outcomes cover changes from baseline in maintenance and rescue medication use, total symptom score, pre- and post-bronchodilator FEV1 percent predicted, Asthma Control Questionnaire score, and Asthma Quality of Life Questionnaire score.
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.
Randomized
| Stage | Alair | Control |
|---|---|---|
| STARTED | 17 | 17 |
| COMPLETED | 15 | 17 |
| NOT COMPLETED | 2 | 0 |
Treatment Period
| Stage | Alair | Control |
|---|---|---|
| STARTED | 15 | 17 |
| COMPLETED | 15 | 17 |
| NOT COMPLETED | 0 | 0 |
Steroid Stable (Post-Tx to 22-Weeks)
| Stage | Alair | Control |
|---|---|---|
| STARTED | 15 | 17 |
| COMPLETED | 15 | 17 |
| NOT COMPLETED | 0 | 0 |
Reduced Steroid (Post-SS to 52-Weeks)
| Stage | Alair | Control |
|---|---|---|
| STARTED | 15 | 17 |
| COMPLETED | 15 | 17 |
| NOT COMPLETED | 0 | 0 |
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 | Alair | Control | Total |
|---|---|---|---|---|
| Participants analysed | 15 | 17 | 32 | |
| Age, Continuous | years | 39.13 (SD 12.97) | 42.06 (SD 12.57) | 40.69 (SD 12.64) |
| Sex: Female, Male: Female | Participants | 9 | 7 | 16 |
| Sex: Female, Male: Male | Participants | 6 | 10 | 16 |
| Region of Enrollment: Canada | participants | 4 | 6 | 10 |
| Region of Enrollment: United Kingdom | participants | 10 | 9 | 19 |
| Region of Enrollment: Brazil | participants | 1 | 2 | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Respiratory Adverse Events Per Subject, measured over Baseline, 12 Months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Respiratory Adverse Events/Subject |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled Respiratory Adverse Events Per Subject. It measures the number of respiratory adverse events divided by the number of subjects in each group during the stated periods. The registry describes events during the Treatment Period and the post-treatment Steroid Stable Phase and Steroid Wean and Reduced Steroid Phase. The timeframe is listed as Baseline, 12 Months.
A per-subject count can describe the burden of events in relation to the number of subjects in a group, rather than reporting only the raw number of events. That distinction is useful when groups have different numbers of subjects. However, the registry does not give the primary endpoint’s numerical results or an analysis comparing the groups. It explicitly says that statistics were not calculated. The information therefore does not establish how precisely any difference between groups was estimated, or whether a formal comparison was made.
General statistical context: event counts may vary substantially between subjects, and some subjects may contribute multiple events. When counts vary more than a simple statistical model expects, over-dispersion can affect uncertainty estimates. Appropriate methods depend on the underlying event data, follow-up, and analysis plan. The registry record does not report the event-level data or a statistical method for this endpoint, so it is not possible to assess those features from the record alone.
The registry also lists secondary outcomes covering medication use, symptoms, lung function, asthma control, and quality of life as changes from baseline. Those measures may describe different aspects of the clinical question, but their results are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a clinically focused randomized comparison: Alair bronchial thermoplasty added to standard therapy versus standard therapy alone. It names respiratory adverse events per subject as the primary outcome, but the key interpretive point is that the record says statistics were not calculated. It does not provide a numerical primary-endpoint result, an estimate of a treatment contrast, a confidence interval, or a p-value. Consequently, the posted record does not support a quantified conclusion about the difference between groups on that endpoint.
The adverse-event listing contains serious-event counts for each group and study phase. During the Treatment Period, 5 of 15 subjects in the Alair group and 1 of 17 in the control group are recorded as having a serious adverse event. During the Steroid Stable Phase, the corresponding counts are 4 of 15 and 1 of 17. During the Steroid Wean and Reduced Steroid Phases, the counts are 2 of 15 and 1 of 17. These are descriptive counts, not an adjusted or inferential comparison. They should not be read as the primary respiratory adverse-event endpoint: the registry presents serious adverse events separately, while the primary outcome is respiratory adverse events per subject.
The record does not give confidence intervals or other measures of uncertainty for the serious-event counts. Without such estimates, the precision of a comparison cannot be judged from the reported counts alone. The counts also do not describe event timing, recurrence within a subject, severity beyond the serious classification, or the details of exposure and follow-up for each individual.
The record lists eight outcome measures and zero analyses. The primary outcome description explicitly says statistics were not calculated, and results for the named secondary measures are not reported in the registry record. No multiplicity procedure, missing-data method, or analysis population is described. These omissions limit interpretation: a statistical comparison can depend on how outcomes, participants, and missing observations were handled, and the registry does not specify those choices.
General statistical context: estimates are more informative when accompanied by uncertainty intervals, because an interval conveys the range of effects compatible with the data under the analysis assumptions. A p-value alone would not express the size or clinical importance of an effect, and a non-significant result would not establish equivalence. In this record, however, neither inferential estimates nor a formal test are reported for the primary endpoint. The defensible reading is therefore descriptive: the record defines the primary measure and lists safety counts, but does not quantify the comparative effect of treatment.
Any planning illustrations associated with these data are hypothetical calculations based on stated assumptions, not observed power and not a substitute for trial results. The registry record does not provide a single primary comparison reduced to an effect estimate with an uncertainty measure. The illustrations should therefore be understood as planning scenarios rather than evidence that the trial did or did not have adequate power.
9. Statistical Methods Explained
The registry records randomized allocation, a parallel-group model, and no masking. Those are design descriptors, not a complete statistical analysis plan. The record does not state how the random sequence was generated or concealed, how the analysis was conducted, or whether any adjustment for baseline characteristics was planned. It is important to distinguish what the design label establishes from what an analysis would require.
What does random allocation contribute?
General statistical context: random allocation aims to make treatment groups comparable, on average, with respect to both measured and unmeasured baseline characteristics. It does not guarantee identical groups, particularly in a small trial. Randomization also does not by itself resolve problems from missing outcomes, deviations from assigned treatment, or incomplete reporting. The registry identifies the study as randomized but does not report the sequence-generation or concealment procedures, participant flow, or analysis population.
The parallel-group design means the registry describes separate groups assigned to the Alair strategy or the control strategy. The Alair group also received standard-of-care therapy, so the intervention contrast is the addition of Alair to that medical management, rather than Alair as a replacement for standard therapy. The record does not provide an analysis explaining whether adherence or treatment changes were incorporated into the comparison.
How should a per-subject count be understood?
The primary endpoint is a count of respiratory adverse events per subject. The registry says the reported quantity was calculated by dividing the number of respiratory adverse events in each period by the number of subjects in the group. This describes an average count per subject, but the record does not report the resulting values. A group-level average also cannot show whether events were spread across many subjects or concentrated in a few.
General statistical context: count outcomes can require methods that account for the distribution of counts and differences in observation time. A simple count model may be unsuitable if the variability exceeds its assumptions; this is often described as over-dispersion. Analyses may also need to account for repeated events within a subject or different lengths of follow-up. The appropriate choice depends on the data and study plan. No such model, adjustment, or event-level description is reported in the registry record, so none can be attributed to this trial.
What can the serious-event counts establish?
The separate serious-adverse-event listing gives the number of subjects at risk and the number affected within each group and phase. These figures support a descriptive reading of how many subjects were recorded as having a serious event in those categories. They do not provide a formal test or an estimate with a confidence interval. Nor do they show the number of events per affected subject. The primary endpoint is respiratory adverse events per subject, and the record does not state that the serious-event listing is a substitute for that endpoint.
General statistical context: a confidence interval expresses uncertainty around an estimate under the assumptions of the analysis. It can help readers assess whether the data are compatible with a range of effects. Without an interval or a specified model, raw counts alone do not show the precision of a between-group comparison. A p-value, if available, would address compatibility with a specified null model, not the size or clinical importance of an effect. No p-value or confidence interval is reported for the primary outcome.
What do the planning assumptions mean?
The record describes sample-size illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The assumed effect to detect is described as a stated fraction of the observed effect. These are planning calculations, not observed power. A planning illustration asks how a future study might perform under specified assumptions; it does not measure the probability that the completed trial’s findings are true, nor does it establish that a treatment effect exists.
Because the primary outcome is not reduced in the record to one comparison, a reader should not treat a planning scenario as a direct inferential result for that outcome. The illustrations are hypothetical and depend on their assumptions. Their interpretation also depends on the effect estimate used as a reference and on the outcome’s statistical model. The registry does not report a detailed sample-size justification or explain how the trial’s planned enrollment was chosen.
Why do analysis details matter?
General statistical context: the meaning of an analysis depends on its target population, outcome definition, handling of missing data, and treatment of multiple outcomes. For example, analyzing participants according to randomized assignment answers a different question from analyzing only those who completed treatment. Missing outcomes can also affect estimates if the reasons for missingness are related to treatment or outcome. These are general considerations, not methods reported for this trial.
The registry lists eight outcome measures and zero analyses. It does not report a statistical analysis plan, analysis population, missing-data approach, multiplicity adjustment, or model for the primary endpoint. The primary outcome description says statistics were not calculated. Therefore, the design can be described, and the recorded counts can be read descriptively, but an inferential analysis cannot be reconstructed from the registry information.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary respiratory adverse-event measure and secondary outcomes covering medication use, symptoms, lung function, asthma control, and quality of life. It records eight outcome measures and zero analyses. The results and statistical analyses for the secondary outcomes are not reported in the registry record. The record does not identify a prespecified hierarchy among outcomes or describe a multiplicity adjustment.
General statistical context: when several outcomes are tested, the chance of at least one apparently unusual result can increase if each is treated as a separate confirmatory test. A prespecified hierarchy or an adjustment can help define how evidence across outcomes should be interpreted. This is a general concern; no specific multiplicity method is reported for this trial. Because outcome results and analysis details are absent, the registry does not support an assessment of how multiple comparisons were handled.
Missing-data methods are not reported in the registry record. The number of subjects included in each primary or secondary outcome analysis, reasons for missing observations, and any imputation or sensitivity analysis are not described. The registry also does not define the analysis population, such as whether participants were analyzed according to randomized assignment or treatment received. The primary outcome population field is blank.
General statistical context: missing-data assumptions matter because conclusions can differ depending on why measurements are unavailable and how those observations are handled. An analysis restricted to observed outcomes may be biased if missingness is related to outcome or treatment. These concerns cannot be evaluated without information on participant flow, missingness, and analysis methods. No particular missing-data mechanism or remedy should be inferred for this study.
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 |
|---|---|---|---|
| Alair (Treatment Period) | 5 | 15 | 33.3% |
| Control (Treatment Period) | 1 | 17 | 5.9% |
| Alair (Steroid Stable Phase) | 4 | 15 | 26.7% |
| Control (Steroid Stable Phase) | 1 | 17 | 5.9% |
| Alair (Steroid Wean and Reduced Steroid Phases) | 2 | 15 | 13.3% |
| Control (Steroid Wean and Reduced Steroid Phases) | 1 | 17 | 5.9% |
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 |
|---|---|
| Alair (Treatment Period) | 15 of 15 |
| Control (Treatment Period) | 17 of 17 |
| Alair (Steroid Stable Phase) | 15 of 15 |
| Control (Steroid Stable Phase) | 15 of 17 |
| Alair (Steroid Wean and Reduced Steroid Phases) | 15 of 15 |
| Control (Steroid Wean and Reduced Steroid Phases) | 15 of 17 |
Most frequent serious adverse event terms
| Event term | Organ system | Alair (Treatment Period) | Control (Treatment Period) | Alair (Steroid Stable Phase) | Control (Steroid Stable Phase) | Alair (Steroid Wean and Reduced Steroid Phases) | Control (Steroid Wean and Reduced Steroid Phases) |
|---|---|---|---|---|---|---|---|
| Dyspnoea/Wheezing | Respiratory, thoracic and mediastinal disorders | 1 of 15 | 0 of 17 | 2 of 15 | 0 of 17 | 2 of 15 | 1 of 17 |
| Dyspnoea | Respiratory, thoracic and mediastinal disorders | 3 of 15 | 0 of 17 | 1 of 15 | 0 of 17 | 0 of 15 | 1 of 17 |
| Atelectasis | Respiratory, thoracic and mediastinal disorders | 1 of 15 | 0 of 17 | 0 of 15 | 0 of 17 | 0 of 15 | 0 of 17 |
| Chest Discomfort | Respiratory, thoracic and mediastinal disorders | 1 of 15 | 0 of 17 | 0 of 15 | 0 of 17 | 0 of 15 | 0 of 17 |
| Cough | Respiratory, thoracic and mediastinal disorders | 1 of 15 | 0 of 17 | 0 of 15 | 0 of 17 | 0 of 15 | 0 of 17 |
| Gallbladder Pain | Hepatobiliary disorders | 1 of 15 | 0 of 17 | 0 of 15 | 0 of 17 | 0 of 15 | 0 of 17 |
| Headache | Nervous system disorders | 0 of 15 | 0 of 17 | 1 of 15 | 0 of 17 | 0 of 15 | 0 of 17 |
| Hernia Repair | Surgical and medical procedures | 0 of 15 | 1 of 17 | 0 of 15 | 0 of 17 | 0 of 15 | 0 of 17 |
| Respiratory Failure | Respiratory, thoracic and mediastinal disorders | 0 of 15 | 0 of 17 | 0 of 15 | 1 of 17 | 0 of 15 | 0 of 17 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Alair (Treatment Period) | Control (Treatment Period) | Alair (Steroid Stable Phase) | Control (Steroid Stable Phase) | Alair (Steroid Wean and Reduced Steroid Phases) | Control (Steroid Wean and Reduced Steroid Phases) |
|---|---|---|---|---|---|---|---|
| Dyspnoea | Respiratory, thoracic and mediastinal disorders | 9 of 15 | 5 of 17 | 5 of 15 | 7 of 17 | 8 of 15 | 10 of 17 |
| Wheezing | Respiratory, thoracic and mediastinal disorders | 11 of 15 | 4 of 17 | 6 of 15 | 2 of 17 | 5 of 15 | 10 of 17 |
| Cough | Respiratory, thoracic and mediastinal disorders | 11 of 15 | 6 of 17 | 2 of 15 | 4 of 17 | 6 of 15 | 4 of 17 |
| Productive Cough | Respiratory, thoracic and mediastinal disorders | 8 of 15 | 4 of 17 | 2 of 15 | 4 of 17 | 8 of 15 | 1 of 17 |
| Lower Respiratory Tract Infection | Respiratory, thoracic and mediastinal disorders | 2 of 15 | 5 of 17 | 2 of 15 | 2 of 17 | 6 of 15 | 2 of 17 |
| Upper Respiratory Tract Infection | Respiratory, thoracic and mediastinal disorders | 1 of 15 | 3 of 17 | 3 of 15 | 1 of 17 | 6 of 15 | 4 of 17 |
| Headache | Nervous system disorders | 3 of 15 | 4 of 17 | 1 of 15 | 3 of 17 | 4 of 15 | 2 of 17 |
| Nasopharyngitis | Infections and infestations | 3 of 15 | 3 of 17 | 2 of 15 | 1 of 17 | 4 of 15 | 4 of 17 |
| Sputum Discoloured | Respiratory, thoracic and mediastinal disorders | 6 of 15 | 2 of 17 | 0 of 15 | 2 of 17 | 3 of 15 | 4 of 17 |
| Chest Discomfort | Respiratory, thoracic and mediastinal disorders | 4 of 15 | 1 of 17 | 1 of 15 | 2 of 17 | 2 of 15 | 6 of 17 |
Serious events with the highest arm-level rate: dyspnoea (20.0%), dyspnoea/wheezing (13.3%), atelectasis (6.7%), chest discomfort (6.7%), cough (6.7%).
The registry lists serious adverse events by study group and phase, with the number at risk and the number affected. During the Treatment Period, serious adverse events are recorded for 5 of 15 subjects in the Alair group and 1 of 17 subjects in the control group. During the Steroid Stable Phase, the figures are 4 of 15 and 1 of 17. During the Steroid Wean and Reduced Steroid Phases, they are 2 of 15 and 1 of 17.
These are descriptive counts for the phases as named in the registry. They are not statistical comparisons, and the record supplies no confidence intervals, p-values, or adjusted estimates for them. The counts do not convey the number of serious events experienced by each affected subject, the timing of events, or the length of each subject’s observation. The record also does not explain whether the same subjects appear in more than one phase, so the phase-specific counts should not be combined.
The registry lists serious-event terms including Dyspnoea, Dyspnoea/Wheezing, Atelectasis, Chest Discomfort, Cough, and Gallbladder Pain, with percentages attached to the terms. The record does not provide enough context to interpret those percentages as a full comparative analysis. These safety listings are separate from the primary endpoint, which is respiratory adverse events per subject and for which the registry says statistics were not calculated.
12. What the Result Does, and Does Not, Mean
The registry establishes the trial’s basic comparison: bronchial thermoplasty with the Alair System plus standard medical management versus standard medical management alone. It identifies respiratory adverse events per subject as the primary outcome and describes the periods in which those events were counted. It also reports serious adverse-event counts by group and phase. These registry entries allow a reader to understand the study question and the type of safety information recorded.
The record does not, however, report a numerical result for the primary endpoint or a statistical comparison between groups. It explicitly states that statistics were not calculated. As a result, it does not provide an estimate of the difference, its uncertainty, or evidence from a formal test. The serious-event counts are descriptive and do not fill that gap. They should not be interpreted as a treatment effect on the primary respiratory-event measure.
The record also names secondary outcomes involving medication use, symptoms, lung function, asthma control, and quality of life, but their results are not reported in the registry record. There is no reported analysis population, missing-data procedure, or multiplicity approach. Without those details and results, the registry cannot establish how the groups compared on those secondary measures or how robust any comparison would be to analytic choices.
General statistical context: a lack of an inferential result is not evidence that groups are equivalent, and descriptive counts alone do not establish a causal effect. Randomization supports a comparative design, but interpretation still depends on complete outcome reporting, appropriate analysis, and uncertainty estimates. The record does not provide enough statistical detail to assess those elements for the primary endpoint.
Any sample-size illustrations should be read only as hypothetical planning scenarios under their stated assumptions. They are not observed power and do not turn descriptive findings into evidence of benefit or harm. The most accurate conclusion from the registry record is limited: it records a randomized comparison and selected safety counts, while leaving the primary comparative estimate and the analyses of secondary outcomes unreported.
13. Why This Trial Matters Statistically
This trial is statistically notable because it pairs a randomized, parallel-group design with a primary endpoint based on event counts per subject. That outcome can describe respiratory-event burden, but interpretation requires more than a label and a denominator. Readers would need the numerical group results, an estimate of the between-group contrast, and a measure of uncertainty to judge how precisely the record distinguishes possible effects.
The registry instead states that statistics were not calculated for the primary endpoint. This makes the boundary between descriptive reporting and inferential evidence especially important. The serious-adverse-event counts provide concrete descriptive information, but they do not answer the primary question and do not quantify uncertainty. Treating them as if they were a formal comparison would overstate what the record documents.
The trial also illustrates why a randomized design does not remove the need for transparent reporting of analysis choices. The record does not report the analysis population, missing-data handling, outcome hierarchy, or multiplicity procedure. These details matter when several outcomes are listed and when clinical interpretation might draw on more than one measure.
General statistical context: planning assumptions and completed-trial results serve different purposes. A planning illustration can describe what a future study might require under specified assumptions; it cannot replace an estimate from the completed trial or establish observed power. Keeping that distinction clear helps prevent design calculations from being mistaken for findings.
For biostatisticians and clinical researchers, the central lesson is to separate the design description, descriptive safety counts, and inferential results. In this registry record, the first two are available in part, while the primary statistical comparison and analyses of the named secondary outcomes are not reported.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The registry record leaves important trial-specific details unavailable. Although it identifies a randomized, multicenter, parallel-group design, it does not describe the randomization sequence, allocation concealment, or implementation. Masking is listed as none, and the record does not say whether any outcome assessors were masked. These gaps limit assessment of how treatment assignment and outcome measurement were protected from bias.
The enrollment field records 34, while the brief summary describes a plan to randomize 30 subjects in a 1:1 ratio. The registry does not explain the difference. It also does not provide a participant-flow account, reasons for withdrawals, group-specific outcome denominators for the primary measure, or details about exposure and follow-up. The primary outcome description gives a calculation approach but not the resulting values, and it states that statistics were not calculated.
The registry lists serious-adverse-event counts, but no inferential analysis or uncertainty estimates. The event-term percentages are listed without enough context in the record to establish their denominator or provide a complete comparative interpretation. No event-level data are reported, so recurrence within subjects and timing cannot be assessed.
Secondary outcome names are present, but results are not reported in the registry record. The record also does not report a statistical analysis plan, analysis populations, missing-data procedures, multiplicity handling, or a sample-size justification. These are specific reporting limitations for interpreting this trial; no unreported protocol or analysis details can be assumed.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Research in Severe Asthma (RISA) Trial — NCT00214539.
- Registry record last updated 2021-02-11; status last verified 2021-01.
- Results first posted 2011-11-07.
- 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 Research in Severe Asthma (RISA) Trial is recorded as a completed, randomized, multicenter, parallel-group study with no masking. It compared bronchial thermoplasty with the Alair System plus standard-of-care therapy against standard-of-care therapy alone in severe asthma refractory to standard medication therapy. The registry records enrollment of 34 and gives a start date of 2004-04 and primary completion date of 2006-02.
The primary endpoint is respiratory adverse events per subject during the Treatment Period and post-treatment phases. The registry states that statistics were not calculated. Serious-adverse-event counts are listed by group and phase, while results for the named secondary outcomes are not reported in the registry record. The record does not report a formal primary comparison, uncertainty estimates, analysis populations, or methods for missing data and multiplicity.