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 The Study of Soy Isoflavones in Asthma (NCT01052116), a randomized phase 4 study. The primary outcome is Mean Change From Baseline to 24 Weeks for FEV1.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01052116 |
| Phase | Phase 4 |
| Condition | Asthma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 386 |
| Arms in the primary outcome | 2 |
| Lead sponsor | American Lung Association Asthma Clinical Research Centers |
| Results posted | Yes |
2. Clinical Question
Population
People with asthma enrolled in the trial. The registry lists an enrollment of 386 and reports 193 in each treatment arm.
Intervention
An oral soy isoflavone supplement, described as 100 mg/day.
Comparator
A matching placebo.
Primary question
What was the mean change from baseline to 24 weeks in FEV1, measured in liters, in each arm?
The trial was designed to study the effects of soy supplements on asthma control. Its primary outcome focuses on FEV1, a measure of the amount of air that can be forcibly exhaled in a specified interval. The registry reports a mean change for each arm and a 95% confidence interval for each mean.
The clinical comparison of interest is whether changes differed between people assigned to the supplement and those assigned to placebo. However, the registry record posts the arm-level estimates without an analysis comparing the arms. It therefore does not report a treatment-effect estimate or a confidence interval for the difference between groups. The arm-specific figures describe the posted outcome summaries; they do not, by themselves, answer whether the groups differed.
The record identifies asthma as the condition, but further details about participant eligibility and the enrolled population are not reported in the registry record. The clinical question should therefore be read in the context of the population details that are actually available, without assuming particular ages, asthma severity, or other characteristics.
3. Trial Design
This was a phase 4, randomized, triple-masked, parallel-group trial sponsored by the American Lung Association Asthma Clinical Research Centers. The registry lists an enrollment of 386. The two arms are Soy Isoflavone and Placebo, with 193 listed in each. The intervention is described as an oral isoflavone supplement at 100 mg/day, and the comparator as a matching placebo.
The study began in 2010-03, had primary completion in 2012-08, and is listed as completed. The registry’s brief summary says the trial was designed to study the effects of soy supplements on asthma control. Its primary endpoint is mean change from baseline to 24 weeks for FEV1, in liters.
Randomized allocation means assignment to the study arms was made through a random process, but the method used to generate or implement that assignment is not reported in the registry record. Triple masking indicates that the record characterizes the trial as triple-masked; which people or roles were masked, and how masking was maintained, are not reported in the registry record. The parallel model means the arms were compared as separate groups over the trial rather than in a crossover arrangement.
Other protocol details are not reported in the registry record. These include the recruitment setting, eligibility criteria, the planned analysis population, adherence procedures, and the sample-size justification. The listed enrollment describes the trial record; it does not establish how many participants had outcome data at the primary assessment. The outcome entries list 193 for each arm, but the registry does not explain how those values relate to missing measurements or the analysis population.
The study’s randomization and masking are relevant design features, but they cannot replace a reported between-arm analysis. The available primary outcome entries are arm-specific summaries, and no analysis is posted for the comparison that addresses the central treatment question.
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 | Soy Isoflavone |
|---|---|---|
| STARTED | 193 | 193 |
| COMPLETED | 179 | 166 |
| NOT COMPLETED | 14 | 27 |
Reasons for not completing this period:
| Reason | Placebo | Soy Isoflavone |
|---|---|---|
| Lost to Follow-up | 11 | 17 |
| Withdrawal by Subject | 3 | 6 |
| Spirometry not performed | 0 | 4 |
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 | Soy Isoflavone | Total |
|---|---|---|---|---|
| Participants analysed | 193 | 193 | 386 | |
| Age, Continuous | years | 38 (17 to 49) | 34 (20 to 49) | 36 (18 to 49) |
| Sex: Female, Male: Female | Participants | 125 | 129 | 254 |
| Sex: Female, Male: Male | Participants | 68 | 64 | 132 |
| FEV1 | Liters | 2.44 (1.96 to 2.93) | 2.40 (2.01 to 2.91) | 2.43 (1.99 to 2.91) |
6. Primary Endpoint
The registry lists the primary outcome as Mean Change From Baseline to 24 Weeks for FEV1, measured over 24 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Liters |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean change from baseline to 24 weeks for FEV1, measured in liters. FEV1 is a measure of expiratory lung function: it records the volume of air forcibly exhaled during the first part of a forced breath. Following change from baseline expresses the outcome relative to each participant’s starting measurement, while the group mean describes the average change among the observations included in the reported summary.
FEV1 is used in asthma research as an objective measure of lung function. It captures one aspect of asthma status, but it is not a complete measure of asthma control or of a participant’s overall experience. Symptoms, exacerbations, medication use, and other outcomes are distinct measures; the registry record does not post secondary outcome results.
The posted mean change is -0.001 liters for Soy Isoflavone, with a 95% confidence interval from -0.07 to 0.07. For Placebo, the mean change is 0.03 liters, with a 95% confidence interval from -0.01 to 0.08. These are separate estimates for the two arms. A direct comparison would estimate the difference in mean change between arms and quantify its uncertainty. That comparison is not reported in the registry record, so the arm-specific endpoint summaries alone do not provide it.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry reports a mean FEV1 change of -0.001 liters for Soy Isoflavone and 0.03 liters for Placebo from baseline to 24 weeks. Each estimate is accompanied by a 95% confidence interval: -0.07 to 0.07 for Soy Isoflavone and -0.01 to 0.08 for Placebo. The intervals describe uncertainty around the arm-specific means as reported. They are not confidence intervals for the difference between arms.
The interval for each arm extends across zero. This means the posted summaries are compatible with values on either side of zero for the mean change, within the range represented by each interval. It does not establish that the arms are equal, nor does it establish a difference between them. A formal comparison requires an estimate of the between-arm contrast and its uncertainty, which are not reported in the registry record.
Comparing whether separate confidence intervals overlap is not a substitute for testing or estimating the difference between groups. The uncertainty of a contrast depends on the variability and covariance structure relevant to that contrast, as well as on the analysis used. Without a reported contrast, its confidence interval, or a test result, the registry entries do not support a precise statistical conclusion about the relative mean changes.
The values are close to zero on the scale of liters, but interpreting their clinical importance requires a meaningful threshold or clinical context. Such a threshold is not reported in the registry record. Nor is there a posted estimate describing what size of change participants or clinicians would consider important. It would therefore be inappropriate to characterize the observed changes as clinically important or unimportant from these entries alone.
The registry lists 193 in each arm alongside the outcome estimates. It does not describe the number with observed measurements at 24 weeks, the method used to handle missing values, or whether the posted means were adjusted for other variables. The outcome summaries should be read as the registry’s posted arm-level results, not as a complete account of the analysis.
No outcome analyses are listed, and the record does not post a p-value or a between-arm effect estimate. The absence of a posted comparison is not evidence that the treatment effect is exactly zero. It is a limit on what can be concluded from the registry record: the arm-level means and their intervals can be described, but a comparative effect cannot be quantified from the results recorded.
9. Statistical Methods Explained
What does a mean change represent? The endpoint is a continuous measurement: FEV1 in liters. A change-from-baseline outcome expresses the follow-up measurement relative to the participant’s baseline measurement. The reported mean summarizes those changes within an arm. It is a group-level average, not a description of every participant’s response. The registry lists mean changes of -0.001 liters for Soy Isoflavone and 0.03 liters for Placebo.
What does a 95% confidence interval convey? A confidence interval describes the statistical uncertainty around an estimate under the assumptions of the method used to calculate it. It gives a range of values compatible with the observed data and that method. It is not a range containing 95% of individual participant outcomes, and it is not a guarantee that the true value lies inside the particular interval. The registry gives intervals of -0.07 to 0.07 for Soy Isoflavone and -0.01 to 0.08 for Placebo.
The record does not describe how these intervals were calculated. It does not report the standard deviation or another measure of spread for the endpoint, the distribution of individual changes, or any adjustment for baseline or other variables. These details matter because different analysis choices can produce different estimates of uncertainty. The reported intervals should therefore be interpreted as posted, without assuming a particular model or calculation procedure.
Why is a direct comparison important? The trial question concerns the difference in outcome between randomized groups. That requires a between-arm estimate, typically a difference in mean change, with an interval or other measure of uncertainty. The registry posts arm-specific means and intervals but lists no analyses. It does not provide a contrast, a test result, or a confidence interval for the contrast. A reader cannot recover the formal comparative result simply by inspecting the two means or their separate intervals.
As a general statistical point, overlap between separate confidence intervals is not a test of the difference between estimates. The precision of the difference depends on uncertainty in both groups and on the method used to estimate the contrast. A direct contrast also makes the target of inference explicit. Here, the registry does not report that contrast, so any claim about the size or precision of a between-arm effect would go beyond the posted results.
What does randomization contribute? In general, random assignment is intended to make treatment groups comparable on average at the start of a trial, including for factors that were not measured. This supports interpreting a properly analyzed between-arm contrast as an effect of assignment, subject to the trial’s conduct and analysis. Randomization alone does not calculate that contrast, guarantee identical groups, or address missing outcome data. The registry identifies the allocation as randomized, but further details of the allocation procedure are not reported in the registry record.
How should masking be understood? The record labels the study triple-masked. In general, masking can reduce the influence of expectations or knowledge of assignment on care, reporting, or measurement. The record does not specify who was masked or how the masking was implemented, so those operational details cannot be assessed from the registry entry. The label is a design characteristic, not a measure of the success of masking.
What do planning calculations mean? In general, a sample-size calculation describes the number of participants a planned study would require under stated assumptions about the effect to detect, the error rate, allocation, and statistical method. A planning illustration based on an observed effect is not an observed trial result and is not observed power. The assumptions described for the planning illustration include a two-sided significance level of 0.05, equal allocation, and a normal approximation. The effect used in the illustration is a stated fraction of the observed effect. No planning sample-size values are reported in the registry record, and this illustration should not be treated as the trial’s original design justification.
Why does over-dispersion matter in general? For count outcomes, over-dispersion means the variability exceeds what a simple model assumes. Ignoring it can make uncertainty estimates too small and statistical evidence appear stronger than warranted. The primary endpoint in this trial is continuous, not a count outcome, so this general issue is not a basis for interpreting its posted FEV1 summaries. The registry does not report an analysis model or diagnostics for the primary endpoint.
Overall, the posted information supports a description of arm-specific mean changes and confidence intervals. It does not support reconstructing the sponsor’s comparative analysis, choosing an unreported model, or resolving how missing data and analysis populations were handled.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary outcome measure: mean change from baseline to 24 weeks for FEV1. It lists no secondary outcome results, and the number of posted secondary outcomes is zero. The record does not report a broader outcome-testing plan, a multiplicity adjustment, or how the primary endpoint was selected in relation to other planned analyses. Those details are not reported in the registry record.
Multiplicity arises when several outcomes, time points, or analyses are tested. In general, conducting many tests can increase the chance of obtaining an apparently unusual result by chance, so a statistical plan may specify how to account for multiple comparisons. With no secondary analyses posted and no analysis plan described, it is not possible to assess the trial’s intended approach to multiplicity. The absence of posted secondary results does not establish that no other outcomes were collected or analyzed.
The registry reports 193 for each arm alongside the primary outcome summaries. It does not state how many participants had an FEV1 measurement at 24 weeks, how missing measurements were handled, whether participants were analyzed according to randomized assignment, or whether any other analysis population was used. These details are important because missing outcomes and exclusions can affect both the estimated mean and its uncertainty.
The adverse-event entries use different listed at-risk counts for serious and other events. Those safety denominators should not be taken as the outcome analysis population. Without information on missingness, exclusions, or the analysis set, the primary outcome estimates cannot be assumed to represent all randomized participants or any particular analysis population beyond the registry’s own reporting.
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 | 12 | 193 | 6.2% |
| Soy Isoflavone | 12 | 193 | 6.2% |
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 | 130 of 186 |
| Soy Isoflavone | 132 of 186 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | Soy Isoflavone |
|---|---|---|---|
| Pulmonary including asthma exacerbation | Respiratory, thoracic and mediastinal disorders | 8 of 193 | 3 of 193 |
| Neuropsychiatric | Nervous system disorders | 0 of 193 | 4 of 193 |
| Musculoskeletal | Musculoskeletal and connective tissue disorders | 1 of 193 | 3 of 193 |
| Gastrointestinal | Gastrointestinal disorders | 0 of 193 | 2 of 193 |
| Reproductive | Reproductive system and breast disorders | 1 of 193 | 1 of 193 |
| Cardiovascular, circulatory, and lymphatic | Cardiac disorders | 0 of 193 | 1 of 193 |
| Renal/urinary | Renal and urinary disorders | 1 of 193 | 0 of 193 |
| Integumentary | Skin and subcutaneous tissue disorders | 1 of 193 | 0 of 193 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | Soy Isoflavone |
|---|---|---|---|
| Difficulty breathing | Respiratory, thoracic and mediastinal disorders | 47 of 77 | 48 of 81 |
| Itching | Skin and subcutaneous tissue disorders | 45 of 139 | 47 of 147 |
| Rash | Skin and subcutaneous tissue disorders | 40 of 160 | 39 of 167 |
| Change in menstrual symptoms | Reproductive system and breast disorders | 33 of 62 | 43 of 71 |
| Difficulty swallowing | Gastrointestinal disorders | 38 of 179 | 31 of 171 |
| Breast tenderness | Musculoskeletal and connective tissue disorders | 24 of 180 | 21 of 175 |
| Hypotension | Blood and lymphatic system disorders | 10 of 182 | 14 of 180 |
Serious events with the highest arm-level rate: pulmonary including asthma exacerbation (4.1%), neuropsychiatric (2.1%), musculoskeletal (1.6%), gastrointestinal (1.0%), cardiovascular, circulatory, and lymphatic (0.5%).
The safety record lists 12 participants affected by serious adverse events among 193 at risk in each arm. It lists 130 affected by other adverse events among 186 at risk in Placebo and 132 among 186 at risk in Soy Isoflavone. These are the registry’s reported counts and denominators; they are not a test of whether the arms differ in safety.
The record lists serious adverse-event categories with percentages: Pulmonary including asthma exacerbation, 4.1%; Neuropsychiatric, 2.1%; Musculoskeletal, 1.6%; Gastrointestinal, 1.0%; Cardiovascular, circulatory, and lymphatic, 0.5%; and Renal/urinary, 0.5%. The registry entry does not clarify the denominator or whether these category percentages are arm-specific or combined. They should not be interpreted as comparative risks for either arm.
Deaths are not reported in the registry record. A blank death entry should not be read as confirmation that no deaths occurred. The safety figures also do not provide event timing, duration, severity beyond the serious classification, or a comparison adjusted for differences in observation time. They describe the safety information recorded, not a complete causal assessment of the intervention.
12. What the Result Does, and Does Not, Mean
The results establish what the registry records for the primary outcome: mean FEV1 change was -0.001 liters in Soy Isoflavone and 0.03 liters in Placebo from baseline to 24 weeks. The corresponding 95% confidence intervals are -0.07 to 0.07 and -0.01 to 0.08. These summaries provide an estimate of each arm’s mean change and indicate uncertainty around each estimate.
They do not establish the size of a difference between arms. The registry record does not post a between-arm estimate, its confidence interval, or a statistical test. The arm-specific results therefore cannot establish that the supplement performed better, worse, or similarly to placebo. A difference in the displayed means is not itself a reported treatment-effect estimate, and separate confidence intervals do not replace a direct comparison.
The results also do not determine whether any observed change is clinically meaningful. The registry does not provide a threshold for an important change in FEV1 or context linking the change to symptoms or other aspects of asthma control. FEV1 represents one measure of lung function and cannot, by itself, describe every outcome relevant to asthma.
The record does not report the missing-data method, analysis population, or full statistical plan. Those omissions limit evaluation of how the estimates were obtained and how broadly they apply to the enrolled participants. The safety information likewise includes counts and category percentages without enough detail to infer a comparative safety effect.
In short, the registry supports a careful description of the recorded arm-level outcome and safety summaries. It does not provide enough comparative analysis to conclude whether assignment to the supplement changed FEV1 relative to placebo, or to quantify the precision of such a difference.
13. Why This Trial Matters Statistically
This trial illustrates why randomized design and comparative analysis are both important. Randomization is intended to support a fair comparison between assigned groups, but the central statistical result is the estimate of the between-arm difference and its uncertainty. The registry record describes a randomized trial and reports arm-specific FEV1 changes, but it does not post that comparative result.
It also highlights the distinction between an estimate and its precision. The reported means give the direction and scale of average change in each arm, while the confidence intervals communicate uncertainty around those means. Neither quantity alone answers the comparative question. Even when arm-level summaries appear close, the appropriate conclusion depends on an analysis of the contrast, not on visual comparison alone.
The endpoint selection matters as well. FEV1 is an objective measure of lung function, but it represents only one dimension of asthma outcomes. A primary endpoint can provide a focused statistical question while leaving other clinically relevant outcomes outside the posted results. Here, no secondary results are reported.
Finally, the record demonstrates why analysis details matter to interpretation. The numbers of participants listed with the endpoint do not explain missing measurements, analysis populations, or the method used to produce the intervals. Without those details, readers should avoid treating the estimates as a complete account of the trial’s statistical evidence. Precise reporting of the contrast, analysis methods, and missing-data handling would make the evidence easier to assess.
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 largest limitation for interpreting the primary outcome is the absence of a posted between-arm analysis. The registry reports a mean change and 95% confidence interval in each arm, but no contrast, confidence interval for the contrast, or p-value. As a result, the comparative treatment effect and its precision are not reported in the registry record.
The registry also does not explain how the confidence intervals were calculated, whether the means were adjusted, or what analysis population was used. Although 193 is listed for each arm with the outcome, the record does not establish whether that represents all randomized participants with measurements at 24 weeks. The handling of missing measurements, withdrawals, or other exclusions is not reported in the registry record.
Important design details are also absent, including eligibility criteria, allocation procedures, the roles covered by triple masking, and the trial’s statistical analysis plan. The record does not provide a sample-size justification. A planning illustration based on an observed effect is not a substitute for information about the original design assumptions.
For safety, the record gives counts and category percentages but does not clarify the scope or denominator for the serious-event category percentages. Deaths are not reported in the registry record. The available adverse-event summaries do not include a comparative analysis or enough detail to assess timing and duration.
These limitations restrict the conclusions that can be drawn from the registry record; they do not establish that the trial lacked additional analyses or information outside that record. Such information is not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Study of Soy Isoflavones in Asthma — NCT01052116.
- Registry record last updated 2016-01-14; status last verified 2015-12.
- Results first posted 2016-01-14.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry identifies NCT01052116, The Study of Soy Isoflavones in Asthma, as a completed phase 4 randomized, triple-masked, parallel-group trial sponsored by the American Lung Association Asthma Clinical Research Centers. The study began in 2010-03 and had primary completion in 2012-08. Enrollment is listed as 386.
The trial compared an oral soy isoflavone supplement described as 100 mg/day with a matching placebo. The primary endpoint was mean change from baseline to 24 weeks for FEV1, in liters. The reported mean changes were -0.001 for Soy Isoflavone and 0.03 for Placebo, with respective 95% confidence intervals of -0.07 to 0.07 and -0.01 to 0.08.
The registry does not post a between-arm analysis, secondary outcome results, or details of missing-data handling and analysis populations. Safety entries report 12 participants affected by serious adverse events in each arm; deaths are not reported in the registry record.