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 Aquatic Treadmill Therapy for Improving Gait, Balance, Fitness and Quality of Life in Stroke Patients (NCT00983827), a na na study. The primary outcome is Safety.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00983827 |
| Phase | NA |
| Condition | Ischemic or Hemorrhagic Stroke, Hemiparesis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 9 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Utah |
| Results posted | Yes |
2. Clinical Question
The study asks whether aquatic treadmill training can be evaluated for safety and for changes in gait economy, gait speed, balance, and cardiovascular fitness among ambulatory adults with chronic stroke. The registry describes the population as people with ischemic or hemorrhagic stroke and hemiparesis. Its brief summary identifies chronic stroke, while the official title specifies ambulatory adult stroke patients.
Population
Ambulatory adults with chronic stroke. The listed conditions are ischemic or hemorrhagic stroke and hemiparesis. The number enrolled was 9.
Intervention
Aquatic treadmill training, described as pool-based treadmill training that combines body unweighting, treadmill training, and the resistance effects of water.
Comparator
No comparator group is described. This was a single-group study, not a randomized comparison, so the registry does not support a like-for-like treatment contrast.
Primary question
The listed primary outcome is safety, measured as the number of procedure-related adverse events during 16 weeks. Gait, balance, fitness, and quality of life appear in the study title and summary, but outcome results for those measures are not reported in the registry record.
These features make the central question descriptive: what safety events were recorded among participants in the aquatic treadmill training group? Without a control group, differences attributable to the training cannot be separated from changes that might occur over time or from other influences. The study title and summary describe broader aims, but the registry record does not report results for those aims.
3. Trial Design
The registry identifies this as a completed pilot study sponsored by the University of Utah. The study began in 2008-05, and primary completion was recorded in 2011-05. Enrollment was 9. The listed intervention was aquatic treadmill training, classified as a device intervention and described as a pool-based treadmill modality.
The design is single-group, with allocation listed as NA and no masking. No separate control arm is described. The absence of a comparator is important: observations made during training can describe what happened among enrolled participants, but they cannot by themselves establish how those observations differ from an alternative treatment or from no training.
The registry lists 16 weeks as the timeframe for the primary safety outcome. It does not report the number of training sessions, session duration, frequency, treatment progression, or criteria for discontinuing training. Those details are not reported in the registry record. The protocol's full eligibility criteria and the specific requirements for ambulatory status are also not reported in the registry record.
The registry lists one outcome measure and no outcome analyses. It does not report an analysis plan, a planned sample-size justification, or the approach used to handle incomplete observations. The record therefore supports a description of the design and the posted adverse-event counts, but it does not support a reconstruction of the intended statistical methods. A pilot designation does not, by itself, establish what sample size was considered adequate or what later study was planned.
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 | Aquatic Treadmill Training |
|---|---|
| STARTED | 8 |
| COMPLETED | 7 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Aquatic Treadmill Training |
|---|---|
| Withdrawal by Subject | 1 |
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 | Aquatic Treadmill Training |
|---|---|---|
| Participants analysed | 8 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 7 |
| Age, Categorical: >=65 years | Participants | 1 |
| Age Continuous | years | 53.5 (SD 6.48) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 6 |
| Region of Enrollment: United States | participants | 8 |
6. Primary Endpoint
The registry lists the primary outcome as Safety, measured over 16 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | adverse events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is safety, expressed as the number of procedure-related adverse events that occurred during the 16-week study timeframe. An adverse-event count is used to describe events recorded during participation; it is not a direct measure of gait, balance, fitness, or quality of life. The endpoint description does not specify how events were defined, how they were assessed, or how a relationship to the procedure was determined. Those details are not reported in the registry record.
Counts can be useful in a pilot study because they provide an account of observed events during the intervention period. However, a count alone does not show how likely an event would be under another intervention or without the intervention. Interpretation also depends on the denominator and on whether the record counts events or participants who experienced an event. The adverse-event record separately gives numbers at risk and affected for serious and other events, but it does not clarify the relation of those entries to the primary endpoint's procedure-related event count.
The registry posts serious and other adverse-event entries for the aquatic treadmill training group. It does not post a separate numerical result for the named primary endpoint as described. Consequently, the event entries should be read as the safety information recorded in the registry, not as a complete estimate of all procedure-related events or as a test of comparative safety.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted record describes a small, single-group pilot, with 9 participants enrolled and aquatic treadmill training as the only listed intervention. The safety entries report 0 serious adverse events among 8 at risk and 2 other adverse events among 8 at risk. These entries describe what was recorded in the intervention group. They do not establish whether the events were caused by the training, and the registry does not provide a control group for comparison.
The enrolled count and the safety denominators are not the same: enrollment is 9, while the safety entries list 8 at risk. The reason for this difference is not reported in the registry record. It should not be assumed that the remaining participant withdrew, was excluded, or had a particular outcome. The record also does not state whether the “other” events were procedure-related, how many distinct events occurred, or whether an individual could have experienced more than one event.
The primary outcome description refers to procedure-related adverse events over 16 weeks, but the registry does not post a separate primary endpoint result or an analysis. No uncertainty interval, hypothesis test, or estimate comparing groups is reported in the registry record. Thus the adverse-event entries allow a limited descriptive reading, but not a precise estimate of the frequency of procedure-related events across a broader population.
In general, an estimate from a small group is uncertain because each observed participant or event can have substantial influence on the summary. A confidence interval, when calculated, expresses uncertainty around an estimate under specified statistical assumptions; it does not remove bias from study design or incomplete reporting. No confidence interval is reported in the registry record, so no such precision measure can be attributed to these results.
The record's study aims include gait economy, gait speed, balance, cardiovascular fitness, and quality of life. Results for those outcomes are not reported in the registry record. Their mention as aims is not evidence that they improved, worsened, or remained unchanged. The same caution applies to safety: absence of a reported serious event in the posted entries is a description of the recorded data, not proof that serious events cannot occur.
Because there is no randomized comparison, observed changes, if measured, could not be cleanly separated from natural variation, concurrent care, practice effects, or other influences. These are general considerations for uncontrolled studies, not findings about what happened to participants in this trial. Overall, the registry supports a narrow account of the listed safety counts and study structure; it does not support a causal efficacy conclusion or a comparison with another approach.
9. Statistical Methods Explained
What can a single-group design estimate?
A single-group study follows participants who receive the same listed intervention. It can describe observed events or measurements within that group. It cannot directly estimate a contrast with a control group because no such group is listed. In a randomized comparison, random allocation is intended to make groups comparable on average; that design feature is absent. Therefore, even if outcome measurements had been posted, a change over time would not by itself identify the intervention as its cause.
The registry lists allocation as NA, masking as none, and the model as single group. The record does not report further details about outcome assessors, participant expectations, or the way measurements were collected. These details matter because awareness of an intervention can influence reported outcomes or some forms of measurement. Whether such influences occurred in this study is not reported in the registry record.
How should a count endpoint be read?
A count endpoint records how many events occur during a defined observation period. The stated primary safety timeframe is 16 weeks. Interpreting a count requires knowing exactly what qualifies as an event, whether the count refers to events or participants with events, how repeated events are handled, and how follow-up time is taken into account. The registry's primary description says “number of procedure related adverse events,” while the adverse-event entries present numbers at risk and affected. Definitions and reconciliation of these measures are not reported in the registry record.
For a count outcome, the number of events and the number of people observed are distinct quantities. A person may experience more than one event, depending on the endpoint definition. The posted entries do not explain whether that occurred, so the recorded count of affected participants should not be treated as a count of all distinct events without further detail. The record also does not explain why 8 participants appear in the safety denominators when enrollment is 9.
In general, count data can vary more than a simple model expects when observations are clustered or when participants have different underlying event rates. This is called over-dispersion. A model that allows for over-dispersion can avoid treating the data as more precise than they are. This is a general statistical consideration; no count model, dispersion estimate, or model-based analysis is reported in the registry record.
What do uncertainty and testing add?
In general, an estimate gives a summary of the data, while a confidence interval gives a range of values compatible with the data under a specified model and confidence procedure. A hypothesis test assesses how inconsistent the data are with a stated null hypothesis under its assumptions. Neither a confidence interval nor a p-value corrects for flaws in design, measurement, or missing information. No confidence interval, p-value, or inferential analysis is reported in the registry record. With no comparator arm, a between-group treatment test is not available from the posted design.
The record lists one outcome measure, but it does not report a statistical analysis plan. It is therefore not possible to tell whether additional outcomes were planned for analysis, which comparisons were intended, whether analyses were adjusted, or what decision rules were specified. The number of outcomes listed does not establish the number of tests performed or the approach to multiplicity.
How should planning illustrations be understood?
Sample-size calculations are planning tools based on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. They are not evidence about the trial's observed outcomes, and they are not “observed power.” The planning illustration associated with the posted material uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it expresses the target effect as a stated fraction of an observed effect. Such an illustration is not the design of this single-group trial, which has no two-arm allocation. It cannot be interpreted as the study's original sample-size justification, which is not reported in the registry record.
For planning in general, calculations based on an observed effect can be unstable, particularly when the observed estimate comes from a small pilot study. A smaller assumed effect generally requires a larger planned study, all else equal; this is a general principle, not a calculation for this trial. The registry record does not report a protocol-based target sample size, the assumed effect used in original planning, or whether any planned sample-size review occurred. No numerical planning estimate should be mistaken for the number enrolled or for evidence that a particular power was achieved.
What can be concluded from the posted analysis information?
The registry lists no outcome analyses. This means it does not present a model, adjustment set, or inferential result for the primary outcome. It does not establish whether investigators performed analyses outside the registry. The analysis population, handling of missing observations, and procedures for checking data quality are not reported in the registry record. Without those details, the safest statistical reading is descriptive: identify the design, state the observed safety entries with their listed denominators, and keep conclusions within those limits.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure, the safety endpoint, and reports no outcome analyses. It does not state whether the study also planned formal testing of gait, balance, cardiovascular fitness, or quality of life, despite those aims appearing in the title and summary. The analysis plan and any approach to multiplicity are not reported in the registry record. It is therefore not possible to determine whether multiple outcomes or repeated measurements were tested, or whether any adjustment was intended.
Missing-data handling is also not reported in the registry record. The reason that 8 participants are listed at risk in the adverse-event entries while enrollment is 9 is not given. There is no reported participant flow, description of withdrawals, or explanation of how incomplete follow-up would be handled. No assumption about the missing participant or their event status is justified from the posted information.
The record does not define an analysis population, such as all enrolled participants or only those with recorded follow-up. It also does not describe exclusions, protocol deviations, or any analysis of participants according to actual exposure. These omissions limit assessment of whether the posted safety denominator represents the full enrolled group or a subset determined after enrollment.
In general, multiplicity concerns arise when several hypotheses or outcomes are examined: the chance of at least one apparently notable result can increase as testing expands. Missing data can also affect interpretation when the likelihood or reason for missingness is related to participant outcomes. These are general statistical concerns, not claims that either problem occurred. The registry does not give enough information to assess their impact.
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 |
|---|---|---|---|
| Aquatic Treadmill Training | 0 | 8 | 0.0% |
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 |
|---|---|
| Aquatic Treadmill Training | 2 of 8 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Aquatic Treadmill Training |
|---|---|---|
| Sharp Head Pain | General disorders | 1 of 8 |
| Fall | Injury, poisoning and procedural complications | 1 of 8 |
The adverse-event entries list 0 serious adverse events among 8 at risk and 2 other adverse events among 8 at risk in the aquatic treadmill training group. These are counts within the posted safety record. They should not be converted into rates or percentages without additional information, and they do not establish a comparison with another group.
The primary endpoint is described as the number of procedure-related adverse events during 16 weeks. The adverse-event entries do not state whether the 2 other events were considered procedure-related, nor do they explain whether affected participants and event counts are equivalent. The record does not provide event descriptions for the other events. The reason that the safety denominator is 8 despite enrollment of 9 is not reported in the registry record.
No serious adverse-event terms are listed, and a death count is not reported in the registry record. A blank or unreported death entry should not be read as a confirmed count of zero. Likewise, 0 serious events in the posted entries describes the observed record; it does not establish that risk is absent. The small enrolled group and lack of a comparator limit what can be inferred about safety beyond these descriptive counts.
12. What the Result Does, and Does Not, Mean
The result that can be stated from the registry is limited: in the aquatic treadmill training group, the adverse-event record lists 0 serious events among 8 at risk and 2 other events among 8 at risk. The study enrolled 9 participants and had no listed control group. These registry entries describe the study record; they do not establish a causal effect of aquatic treadmill training.
The record does not report a separate numerical result for the primary endpoint of procedure-related adverse events. It also does not report results for gait economy, gait speed, balance, cardiovascular fitness, or quality of life. Although those outcomes are part of the study's aims, their direction and magnitude cannot be inferred from the title or summary. No change score, comparison, or measure of uncertainty for these outcomes is reported in the registry record.
In general, a safety count from a group receiving an intervention is not a counterfactual comparison. It does not show what would have happened to the same participants under another approach. An uncontrolled design also cannot distinguish intervention-related change from other explanations, such as time, concurrent care, or natural variation. These are limits of the design, not evidence that any particular explanation occurred in this study.
The absence of reported serious events in the posted entries should be interpreted narrowly. It is not proof that serious events are impossible or that the intervention is safe for all people with stroke. The small enrolled group, the difference between enrollment and the listed safety denominator, and the lack of event definitions and attribution details all constrain interpretation.
The appropriate statistical takeaway is therefore descriptive rather than comparative: the registry contains a limited set of safety counts from a completed pilot study, but it does not provide a full endpoint analysis or efficacy results. Further conclusions about treatment effects, precision, or generalizability are not supported by the registry record.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between a study's aims and the results that are available for analysis. The title and summary describe several functional outcomes, while the listed primary endpoint is safety. The registry record does not report results for the functional outcomes or a separate estimate for the primary endpoint. A clear description of this gap helps prevent stated aims from being mistaken for observed findings.
The design also illustrates why the comparator matters. A single-group pilot can document experience with an intervention, but without a control group it cannot estimate a treatment contrast. The listed adverse-event counts are therefore useful as descriptive observations, not as comparative evidence. This distinction remains important even when a study is completed and has a named sponsor.
The difference between enrollment of 9 and safety denominators of 8 is another relevant reporting feature. Without participant flow or an explanation, readers cannot determine why the denominators differ or how the data were handled. The registry record does not establish that the discrepancy reflects missing follow-up, withdrawal, or exclusion; it simply leaves the reason unresolved.
Finally, the record lists no analyses. Statistical interpretation depends not only on which outcomes are named, but also on definitions, denominators, analysis populations, and methods for representing uncertainty. Those details are not reported in the registry record. Reading the entries descriptively, while separating them from unreported analyses and broader claims, is the most defensible way to understand what this pilot contributes.
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 main limitations specific to this study are its single-group design and the absence of a comparator. The study can describe observations in the aquatic treadmill training group, but it cannot supply a like-for-like estimate of how outcomes differ under another approach. Allocation is listed as NA, and the registry identifies no randomization.
Enrollment was 9, while the serious and other adverse-event entries each list 8 at risk. The reason for this denominator difference is not reported in the registry record. Participant flow, missing follow-up, withdrawals, and exclusions are not described. This prevents a clear assessment of how fully the safety entries represent all enrolled participants.
The primary endpoint is described as procedure-related adverse-event count during 16 weeks, but the registry does not provide a separate result for that endpoint. Event definitions, attribution procedures, and whether the posted entries count events or affected participants are not reported. The death count is not reported in the registry record.
Although the study aims include gait economy, gait speed, balance, cardiovascular fitness, and quality of life, results for these measures are not reported in the registry record. No analysis plan, confidence interval, hypothesis test, or outcome analysis is listed. The criteria for eligibility, training dose, adherence, and measurement procedures are also not reported in the registry record. These limitations restrict both statistical interpretation and the ability to judge how applicable the observations may be beyond the enrolled group.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Aquatic Treadmill Therapy for Improving Gait, Balance, Fitness and Quality of Life in Stroke Patients — NCT00983827.
- Registry record last updated 2013-01-15; status last verified 2012-12.
- Results first posted 2013-01-15.
- 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
This completed pilot study, sponsored by the University of Utah, enrolled 9 ambulatory adults with chronic stroke and evaluated aquatic treadmill training in a single group. The intervention combined pool-based treadmill training, body unweighting, and water resistance. The study began in 2008-05, with primary completion in 2011-05.
The listed primary outcome is the number of procedure-related adverse events during 16 weeks. The adverse-event entries report 0 serious events among 8 at risk and 2 other events among 8 at risk. The reason for the difference between enrollment and the listed safety denominators is not reported in the registry record.
No comparator group or outcome analyses are listed. Results for the gait, balance, fitness, and quality-of-life aims are not reported in the registry record. The available safety counts are descriptive and do not establish comparative effects or a causal relationship to the intervention.