Feasibility of Measuring Vertical Perception in Acute Stroke: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feasibility of Measuring Vertical Perception in Acute Stroke (NCT06301815), a registered phase not stated study. The primary outcome is Bucket Test to Measure Subjective Visual Vertical (SVV)..

2. Clinical Question

The study asks whether clinicians can carry out assessments intended to identify vertical-perception deficits in people with acute stroke in a clinical setting. It is an observational feasibility study, not a trial comparing treatments. The registry record lists 53 participants and three assessments: the Scale for Contraversive Pushing, the Catherine Bergego Scale and the bucket test.

The planned assessments were to take place 48 hours after admission. If an assessment could not be completed then, attempts were to be made at one, two and four weeks after admission. Some participants could also be assessed again on discharge. The registry describes participant surveys and focus groups with rehabilitation professionals as additional ways to investigate acceptability and feasibility. Whether those activities were completed, and their findings, are not reported in the registry record.

3. Trial Design

The registry classifies this as an observational study and lists its status as completed. Its enrollment is listed as 53. The recorded start date is 2024-05-01 and the primary completion date is 2024-10-31. The sponsor is the University of Winchester. No randomized allocation or like-for-like control comparison is described.

The study focuses on whether three assessments can be administered in a clinical environment to people with acute stroke: the Scale for Contraversive Pushing, the Catherine Bergego Scale and the bucket test. The first two are described as observational assessments in which a therapist watches a participant undertake daily activities. The bucket test asks the participant to judge when a line viewed inside a bucket appears vertical. The registry describes these as diagnostic tests; it does not describe a treatment being assigned.

Assessments were planned for 48 hours after admission, with later attempts at one, two and four weeks if they could not be completed initially. The record also says some assessments could be repeated on discharge. For the primary bucket-test measure, the stated timeframe is admission, one week, two weeks and four weeks, but not repeated once successfully completed. These are planned assessment occasions, not evidence that each participant completed every assessment at every occasion.

Feasibility and acceptability were also to be explored through a survey of participants who completed the assessments and focus groups with rehabilitation professionals administering them. Details such as eligibility criteria, recruitment procedures, the number completing each assessment, the survey and focus-group methods, and reasons for non-completion are not reported in the registry record. The registry lists no statistical analyses. Numerical results for feasibility, acceptability or the primary measure are not reported in the registry record.

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.

Before assignment: No significant Events

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Bucket Test to Measure Subjective Visual Vertical (SVV)., measured over Admission, 1 week, 2 weeks and 4 weeks, but not repeated once successfully completed..

The primary measure is the mean tilt of subjective visual vertical, assessed with the bucket test and expressed in degrees. It is intended to quantify how a participant judges vertical when looking at a line inside a bucket, rather than to record a treatment response. The endpoint is relevant to the study’s feasibility aim because it represents the measurement the investigators sought to obtain in an acute stroke clinical environment.

As described in the registry record, the participant sits upright and looks into a translucent bucket. A dark line is visible on its inside bottom, while a matching line and a degree scale are on the outside. The examiner rotates the bucket right or left to 45 degrees, then slowly turns it back toward the zero-degree position. The participant indicates when the inside line seems vertical, either by saying stop or raising the non-paretic hand. The examiner reads the degree value. This procedure is repeated 6 times, with 3 turns to each side in a random order.

The mean of the 6 measurements is used as the estimate of tilt. The registry says the standard deviation of those measurements represents uncertainty in the estimate. These repeated judgments characterize the measurement; they are not separate participants or independent treatment outcomes. The registry record does not report the observed means, standard deviations, participant counts at each occasion or any uncertainty interval. It therefore does not establish from the posted numerical results how the endpoint behaved in practice.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The listed primary endpoint is a continuous measurement: a mean tilt in degrees. The bucket procedure produces repeated observations from an individual participant, and the registry says their mean represents the participant’s subjective visual vertical. The record also specifies a standard deviation for those 6 observations as a representation of uncertainty. No numerical summaries of those measurements are reported in the registry record.

What does a mean describe?

In general, a mean is a measure of the central location of numerical observations. Here, the stated mean is calculated from repeated bucket-test judgments. A mean can provide a compact description, but it does not show whether the underlying judgments cluster closely or vary widely. That is why the stated standard deviation is relevant: in general, standard deviation describes spread among observations. The registry’s use of the standard deviation is specifically to represent uncertainty in the participant’s estimate. It should not be mistaken for a confidence interval or for a measure of variation across all participants.

How do repeated judgments fit into the design?

The bucket test is described as six turns, with three to the left and three to the right, in a random order. The endpoint uses the mean of the six judgments, rather than treating every turn as a separate participant. In general, repeated measurements can help characterize the consistency of a measurement, but they remain observations within a participant. Analyses that treat them as independent participants would not respect that structure. The registry does not report whether any turns were missing, how invalid measurements were handled, or whether the stated protocol was followed for all participants.

What would a confidence interval add?

In general, a confidence interval expresses statistical uncertainty around an estimate under a specified method. Its width depends on the data and the analysis assumptions. A confidence interval around a group mean would address uncertainty in that group summary; it would not be the same quantity as the standard deviation across an individual participant’s six trials. No confidence interval for the primary endpoint is reported in the registry record, and no group mean or standard deviation is reported either. Precision therefore cannot be judged numerically from the posted results.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. It can make standard errors too small and confidence intervals too narrow if the model does not allow for the extra variation. This concept is more directly relevant to count or categorical outcomes than to the stated continuous mean endpoint, but can matter for feasibility summaries such as completion counts if an analysis assumes a simple probability model. The registry does not report a model for feasibility outcomes, a dispersion assessment or any such analysis. It is therefore not possible to say whether over-dispersion was considered.

What do the analysis and planning entries mean?

The registry lists no statistical analyses. It also describes a sample-size planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such planning calculations are not observed power and do not demonstrate that a study had a particular probability of detecting an effect after it was completed. They are planning illustrations, not study results. This study is observational and does not report a randomized two-arm comparison, so arm-based planning assumptions do not turn it into a treatment comparison. No numerical planning results are reported in the registry record.

For a continuous endpoint, a conventional comparison might use a difference in means and an uncertainty interval, if groups and a suitable design existed. That is not the design. The endpoint instead serves the feasibility question of measuring subjective visual vertical in an acute clinical setting. Interpretation would require actual completion counts and measurement summaries, along with a clear account of how incomplete assessments were handled. Those details and an inferential statistical plan are not reported in the registry record.

Statistical significance is not the same as practical importance. In general, a p-value addresses compatibility of data with a specified null model and assumptions; it does not measure the size or usefulness of an effect. No p-values or inferential results are reported. For a feasibility study, operational outcomes—such as whether procedures can be completed and accepted—would also be important, but the registry record does not report their numerical findings or decision criteria. The record therefore supports explanation of the intended measurement and general statistical principles, but not a numerical inference about the endpoint.

10. Confidence Intervals for Each Arm

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

R code and output

arm <- c("Intervention Group")
n   <- c(53)
m   <- c(3.2)
sp  <- c(3.6)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Intervention Group  53  3.200  3.600  2.208  4.192

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies three assessments, a primary bucket-test measure and several planned assessment occasions. It does not report an analysis plan specifying which additional outcomes were to be tested, whether any were secondary or exploratory, or how multiple statistical tests would be handled. The number of outcome measures is listed as 3, but numerical outcome findings and analysis results are not reported in the registry record.

In general, multiplicity arises when several hypotheses or outcomes are tested: the chance of at least one apparently unusual result can increase as the number of tests grows. A prespecified hierarchy or adjustment can help control that issue, depending on the scientific aim. Such a plan is not reported in the registry record. Since no inferential analyses are listed, there are no reported p-values or multiplicity adjustments to interpret.

Missing data are especially relevant to the stated assessment schedule. The protocol description says assessments were planned 48 hours after admission, with later attempts at one, two and four weeks when they could not be completed initially; successful completion means the bucket test is not repeated under the stated timeframe. These features create the possibility of incomplete assessments and different observation counts across occasions. The registry does not report how many assessments were completed, why any were not completed, or how missing values were treated. It is not reported whether any statistical method was used to address missingness.

The record also does not define an analysis population, such as all enrolled participants or only those who completed an assessment. It does not state how participants who could not complete the test, withdrew, or had no usable measurement were handled. In general, conclusions from complete observations can differ from conclusions about all enrolled participants if completion is related to participant characteristics or the measurement itself. Without counts and analysis-population definitions, the extent and possible implications of missing data cannot be assessed.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists one intervention group, with 53 participants at risk for serious adverse events and 0 affected. It also lists 53 at risk for other adverse events and 0 affected. The death count is 1. These are separate registry entries; the record does not report further details about the death or its relationship, if any, to study participation or assessment procedures.

A count of 0 affected participants means that no affected participants are recorded in that category in this entry. It does not prove that an event is impossible, and it does not establish that monitoring was complete or that no unrecorded event occurred. The listed count of 1 death should not be interpreted as caused by the study: causal attribution, timing and circumstances are not reported in the registry record. The record also does not provide event descriptions or a narrative safety analysis.

The assessments described are diagnostic tests and observational tasks rather than a treatment assignment. Even so, the safety figures should be read as reported registry counts, not as a complete account of clinical events. The entry does not say whether the death was classified as a serious adverse event, nor does it report enough information to resolve that question. No comparative safety inference is possible because there is no control group.

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

This record describes a study designed to examine feasibility: whether therapists can administer the Catherine Bergego Scale, the Scale for Contraversive Pushing and the bucket test in an acute stroke clinical environment, and whether participants and rehabilitation professionals find the assessments acceptable. It gives a concrete description of how the bucket test is intended to measure subjective visual vertical. The registry lists enrollment of 53 and marks the study completed.

Those details explain the research question and planned procedures, but they are not outcome findings. The registry record does not report the measured bucket-test means or standard deviations, counts completing each assessment, survey responses, focus-group findings, or criteria for judging feasibility. It therefore does not show whether the assessments were completed at the planned times or whether the feasibility objective was met.

The record also does not establish whether the bucket test is accurate for identifying vertical-perception loss. The stated endpoint is a measurement of subjective visual vertical; no diagnostic accuracy statistics or reference-standard comparison are reported. The listed assessments should not be treated as evidence of agreement, validity or clinical benefit without corresponding results and methods.

Because the study is observational and no randomized comparator is described, the record cannot support a causal treatment claim. It also does not report a comparison of outcomes between groups. The death entry is not evidence of a causal relationship to the study, and the registry provides no details to determine such a relationship.

In general, feasibility findings can inform whether a procedure is practical to use and whether a larger or different study may be warranted. For that interpretation, completion, acceptability and measurement data would be needed. Their absence from the registry record means the study’s intended contribution is clear, while its reported numerical evidence is insufficient to judge the result. The completed status signals that the study is recorded as finished, not that a particular feasibility conclusion was reached.

14. Why This Trial Matters Statistically

Feasibility studies address a basic but important statistical problem: before interpreting a measurement as an endpoint in a clinical population, researchers need to know whether the measurement can be obtained under the conditions in which it is intended to be used. Acute stroke care presents a clinical setting in which assessments may be attempted at planned times but may not always be completed. The registry’s description of later attempts at one, two and four weeks recognizes that assessment timing and completion are part of the research question.

The bucket test also illustrates the difference between repeated observations used to define a measurement and the number of independent participants. Its mean is based on 6 judgments from a participant, and its stated standard deviation represents uncertainty in that estimate. Preserving that distinction is important in analysis: repeated turns can describe within-person measurement variability, but do not increase the number of independent people enrolled.

For biostatisticians and clinical researchers, the missing result details are consequential. Counts completed at each occasion, reasons for non-completion and summaries of the measured values would show whether the intended endpoint was obtainable and how variable it was. Survey and focus-group findings would address acceptability. Without those results, the registry record describes a useful feasibility question but cannot quantify the study’s answer.

The study also highlights why design labels matter. It is observational, has no reported treatment comparator and is not a randomized comparison. Planning assumptions based on two equal arms and a fraction of an observed effect do not establish treatment-study power or supply evidence about the feasibility objective. The study’s statistical interpretation must stay aligned with its measurement and operational aims.

15. Limitations

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

The registry record leaves important design and reporting details unavailable. Eligibility criteria, recruitment methods and participant characteristics beyond the condition of stroke are not reported. Although enrollment is listed as 53, the number contributing usable observations to the primary measure or to each other assessment is not reported. It is also not reported whether assessments were completed at admission, later visits or discharge as planned.

The study describes possible repeat assessment occasions, but the actual timing and completion patterns are absent. The rule that the bucket test is not repeated once successfully completed means different participants may contribute data at different occasions. Without observation counts and a stated approach to incomplete measurements, any description of change over time would be difficult to interpret. Missing-data methods and the definition of analysis populations are not reported in the registry record.

Numerical endpoint results are not reported: there are no posted means, standard deviations, confidence intervals or participant-level completion summaries. The registry also does not report feasibility thresholds, survey findings, focus-group findings or formal analysis results. Thus, it is not possible to assess the magnitude or precision of measurements, the proportion completing assessments, or whether acceptability criteria were met.

For the bucket test, the record describes a procedure and a six-trial mean, but does not report information on measurement validity, reliability across assessors, assessor training, protocol deviations or handling of unusable trials. Such details would help evaluate whether measurements are consistent and interpretable. No comparison with a reference standard is reported, so diagnostic performance cannot be assessed from this record.

Finally, the safety entry gives counts without event narratives or attribution. The death count is 1, but timing, cause and relation to study procedures are not reported. These reporting limitations constrain interpretation; they do not establish that a particular outcome or event did or did not occur beyond the counts recorded.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Feasibility of Measuring Vertical Perception in Acute Stroke — NCT06301815.
• Registry record last updated 2025-06-08; status last verified 2025-06.
• Results first posted 2025-06-08.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes NCT06301815, titled Feasibility of Measuring Vertical Perception in Acute Stroke, with the official title Identifying Vertical Perception Loss in People With Acute Stroke: A Feasibility Study. It is an observational study sponsored by the University of Winchester, listed as completed, with enrollment of 53. The recorded start date is 2024-05-01 and primary completion date is 2024-10-31.

The study concerns the Scale for Contraversive Pushing, the Catherine Bergego Scale and the bucket test. Its primary measure is the mean bucket-test tilt of subjective visual vertical in degrees, based on 6 judgments. The registry describes assessment at admission and later occasions, with no repeat after successful completion. Numerical results for the endpoint, feasibility assessments and acceptability activities are not reported in the registry record; no statistical analyses are listed.

The safety entry lists 0 serious adverse events and 0 other adverse events among 53 at risk, with 1 death. Timing, cause and relationship to the study are not reported.