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 Visual Function During Gait in Parkinson's Disease: Impact of Cognition and Response to Visual Cues (NCT02610634), a registered phase not stated study. The primary outcome is Visual Sampling Parameter: Saccade Frequency During Gait.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02610634 |
| Phase | Phase not stated |
| Condition | Parkinson's Disease |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 100 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Newcastle-upon-Tyne Hospitals NHS Trust |
| Results posted | Yes |
2. Clinical Question
Population
People with Parkinson’s disease who were at least 50 years old and did not have dementia, defined in the registry description as a MoCA score of 21 or higher. The comparison group comprised age-matched older adults who were at least 50 years old and cognitively intact, defined as a MoCA score of 26 or higher.
Intervention
The record describes gait assessments under several walking conditions: single task, dual task, walking through a doorway, turning, and walking with a visual cue. It does not describe a randomized treatment intervention or allocation to intervention groups.
Comparator
The described comparison is between the Parkinson’s disease group and the older-adult group. The registry record says the comparison was not randomized and does not state how allocation or group formation was conducted. These groups should not be read as randomized treatment and control arms.
Primary question
The study asks about visual sampling during gait, focusing on the frequency of fast eye movements, called saccades. Its title also identifies cognition and response to visual cues as topics of interest. The registry describes measurement during different walking tasks, but does not report numerical outcome results or a detailed statistical hypothesis.
3. Trial Design
The registry identifies this as a completed study with an enrollment of 100. Its stated sponsor is Newcastle-upon-Tyne Hospitals NHS Trust. The recorded study start is 2013-07, and the primary completion date is 2015-02. The record describes two groups: people with Parkinson’s disease and older adults. It characterizes the older adults as age-matched, but the matching procedure and any other methods used to form or recruit the groups are not reported in the registry record.
Participants in the Parkinson’s disease group were described as at least 50 years old and without dementia, with a MoCA score of 21 or higher. The older-adult group was described as at least 50 years old and cognitively intact, with a MoCA score of 26 or higher. These different cognitive eligibility thresholds are important context for interpreting a group comparison: the record does not establish that the groups were otherwise equivalent.
The registry characterizes this as a non-randomized comparison and says that allocation was not stated. It therefore should not be interpreted as a randomized trial comparing assigned treatments. The primary outcome was to be observed during gait assessments in Session 1, described as lasting approximately 90 minutes. Walking conditions included single-task and dual-task walking, a doorway, turning, and a visual cue. The record names electrooculography (EOG) and a Dikablis mobile eye-tracker as measurement devices. Further details of recruitment, assessment order, masking, protocol conduct, or the analysis plan 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.
Overall Study
| Stage | Parkinson's Disease | Older Adults |
|---|---|---|
| STARTED | 60 | 40 |
| COMPLETED | 60 | 40 |
| 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 | Parkinson's Disease | Older Adults | Total |
|---|---|---|---|---|
| Participants analysed | 60 | 40 | 100 | |
| Age, Continuous | years | 67.8 (SD 7.6) | 66.9 (SD 10.9) | 67.4 (SD 9.0) |
| Sex: Female, Male: Female | Participants | 22 | 17 | 39 |
| Sex: Female, Male: Male | Participants | 38 | 23 | 61 |
| Region of Enrollment: United Kingdom | participants | 60 | 40 | 100 |
6. Primary Endpoint
The registry lists the primary outcome as Visual Sampling Parameter: Saccade Frequency During Gait, measured over Session 1: observation during gait assessments (lasting approx. 90mins).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Saccade frequency (sacc/sec) |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the mean frequency of saccades during gait, expressed as saccades per second. A saccade is a fast eye movement. The registry describes the measure as the number of fast eye movements made per second while walking, assessed with EOG and a Dikablis mobile eye-tracker. It includes observations under several walking conditions: single task, dual task, going through a doorway, turning, and walking with a visual cue. The stated timeframe is Session 1, during gait assessments lasting approximately 90 minutes.
In general, measuring saccade frequency offers a way to describe one aspect of how a person visually samples the environment while moving. It is not a direct measure of all visual or cognitive function, nor does the endpoint by itself establish whether a person can safely navigate a particular environment. Its interpretation depends on the assessment conditions, measurement quality, and the methods used to summarize observations across tasks. The registry specifies a mean and standard deviation as the summary format, but does not report the endpoint values, group estimates, or a statistical comparison. Consequently, the posted record does not establish the direction or size of any difference in saccade frequency.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes the purpose and measurement of a study of visual sampling during gait, but it does not report numerical results for the primary endpoint or the listed secondary outcomes. It records 27 outcome measures and zero analyses. No group means, standard deviations, effect estimates, confidence intervals, or p-values for the outcomes are reported in the registry record. The study’s title and outcome descriptions identify questions of interest; they do not supply evidence about the direction or magnitude of an observed group difference.
The primary outcome is a continuous measure: mean saccade frequency during gait. A useful interpretation of a continuous group comparison would ordinarily consider the estimated difference, its uncertainty, the variability of observations, and the assessment conditions. Those quantities are not reported in the registry record. Without them, neither the size nor precision of a possible difference can be assessed. In particular, the absence of numerical outcome results should not be mistaken for evidence that the groups had identical measurements.
The groups also differ in how they are described. The Parkinson’s disease group had a MoCA eligibility threshold of 21 or higher, while the cognitively intact older-adult group had a threshold of 26 or higher. The record describes the groups as age-matched, but does not report the matching procedure. It also says the comparison was not randomized and allocation was not stated. Therefore, any between-group contrast would need to be interpreted as a comparison of these described groups, not as an isolated causal effect of Parkinson’s disease or of a visual cue. Other group differences and features of recruitment could influence a contrast; their role cannot be evaluated from the registry information.
The listed gait conditions may also matter to interpretation. Single-task walking, dual-task walking, doorway passage, turning, and a visual cue are distinct assessment contexts. The registry does not report results by condition, how repeated observations were combined, or whether the primary estimate represents a particular condition or an overall summary. It likewise does not report the number of participants with usable measurements for each outcome.
The record’s planning description refers to illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It gives no numerical observed effect or planning results in the registry record for interpretation. Such planning illustrations would not be observed power or evidence of an outcome. Overall, the registry supports a description of the research question and measurement approach, but not a conclusion about observed saccade frequency or the precision of a group comparison.
9. Statistical Methods Explained
The registry specifies a continuous primary measure summarized as a mean with a standard deviation. In general, a mean describes the average value in a group, while a standard deviation describes how spread out individual measurements are around that average. Neither statistic is reported for the primary endpoint in the registry record. Even when means and standard deviations are available, they describe the data rather than, by themselves, establish the uncertainty in a comparison between groups.
In general, an effect estimate expresses the size and direction of a contrast, while a confidence interval describes a range of values compatible with the data and analysis under its assumptions. A narrow interval indicates greater precision than a wide interval, but it does not remove concerns about design or measurement. The registry record does not report an effect estimate or confidence interval for saccade frequency. It also does not report a p-value. No statistical significance claim can therefore be assessed from the recorded outcome information.
The primary outcome is measured during walking, using EOG and a Dikablis mobile eye-tracker. The registry describes five kinds of walking context: single task, dual task, passing through a doorway, turning, and walking with a visual cue. In general, repeated or condition-specific measurements require a clear definition of what is being summarized and how within-person observations are handled. The record does not describe whether the primary mean is calculated across conditions, how measurements from repeated tasks are combined, or whether the analysis accounts for their dependence. It also does not report device calibration procedures, signal-processing rules, or criteria for excluding unusable recordings.
The record lists gait speed, step length, step time, single support time, and double support time as secondary gait outcomes. It also lists saccade number, velocity, and amplitude during gait as secondary visual-sampling outcomes. These are distinct measures and should not be treated as interchangeable with the primary measure of saccade frequency. The registry reports 27 outcome measures overall, but does not provide numerical results for those measures or explain how the listed outcomes relate to the full set.
In general, over-dispersion means that observed variability is greater than a statistical model assumes. When a model underestimates variability, its uncertainty estimates may be too small and its inferential results too optimistic. This is a general consideration for statistical analysis, not a reported finding about these data: the registry does not identify a fitted model, report a dispersion assessment, or state that over-dispersion occurred. More broadly, the analysis method, covariate adjustment, handling of repeated measurements, and assumptions used for the outcome analysis are not reported in the registry record.
The registry’s planning description says that its sample-size illustrations use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. The available registry information does not give the observed effect or numerical planning results. These are planning illustrations, not observed power. In general, a planning calculation estimates the sample size needed under specified assumptions; it does not show that a study had a particular probability of detecting an effect after the data have been collected. The record does not report the trial’s own sample-size justification, so the illustrations should not be attributed to the original design.
The registry describes a non-randomized comparison, with allocation not stated. In general, randomization can help balance both measured and unmeasured participant characteristics between assigned groups. Without randomization, group contrasts may reflect differences beyond the feature of interest. The record does not report an adjustment strategy that would address such differences. Thus, even if numerical outcome results were available, the design description would call for cautious interpretation of between-group associations rather than a causal claim.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists multiple outcomes: gait measures, visual-sampling measures, and 27 outcome measures overall. Considering many outcomes or comparisons can increase the chance of observing an apparently unusual result by chance. In general, a prespecified multiplicity strategy can define how such testing is handled. The registry record does not report whether outcomes were tested, which comparisons were planned, or whether any adjustment for multiple testing was used. It also does not report an analysis plan that identifies a hierarchy among outcomes beyond naming the primary endpoint.
Missing data are another important consideration for continuous outcomes. In general, an analysis should make clear how many participants contributed usable data to each outcome and how missing or unusable measurements were handled. The registry record does not report outcome-specific participant counts, reasons for missing data, imputation methods, or sensitivity analyses. It is therefore not possible to assess whether the recorded groups and any potential outcome summaries would represent all enrolled participants or only those with usable measurements.
The analysis populations are not described in the registry record. No information is reported about exclusions after enrollment, adherence to assessment procedures, or whether all enrolled participants were included in each analysis. The record lists zero analyses and gives no numerical outcome results. As a result, neither the extent of missingness nor the consequences of analysis-population choices can be evaluated from the registry information.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Parkinson's Disease | 0 | 60 | 0.0% |
| Older Adults | 0 | 40 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Parkinson's Disease | 0 of 60 |
| Older Adults | 0 of 40 |
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 |
|---|---|
| Parkinson's Disease | 0 of 60 |
| Older Adults | 0 of 40 |
The registry’s adverse-event figures list 60 participants at risk in the Parkinson’s disease group and 40 in the older-adult group. Serious adverse events affected 0 participants in each group. Other adverse events also affected 0 participants in each group, and deaths were recorded as 0 in both groups. No serious adverse-event terms are listed.
These figures describe what the registry record reports; they do not establish that no events occurred outside the record’s reporting scope or observation procedures. A zero count is not proof of zero risk. The registry does not report the method or duration used to collect adverse-event information, how events were defined, or how complete the reporting was. The assessment timeframe for the primary outcome is Session 1, approximately 90 minutes, but that does not by itself establish the period covered by adverse-event monitoring. The figures should therefore be read as recorded counts, not as a comprehensive safety assessment or a comparison of risks.
12. What the Result Does, and Does Not, Mean
The registry record identifies a study question about visual sampling during gait in people with Parkinson’s disease and older adults, and describes saccade frequency as the primary outcome. It also identifies several gait conditions and other gait and visual-sampling measures. These details explain what the study set out to measure and provide context for the comparison it describes.
What the record does not establish is the observed result. Numerical outcome estimates, measures of uncertainty, and statistical test results are not reported in the registry record. It is therefore not possible to say from these registry entries whether saccade frequency differed between groups, in which direction it might have differed, or how precisely any difference was estimated. The lack of posted numerical results should not be interpreted as evidence of no difference.
The design description also limits what a group contrast could mean. The comparison was not randomized, and allocation was not stated. The older-adult and Parkinson’s disease groups have different cognitive eligibility thresholds, and the record does not describe the matching procedure or report an adjustment strategy. In general, differences between non-randomized groups can reflect characteristics other than the group label. A comparison would consequently need to be interpreted in light of these design features, rather than as proof that a particular factor caused a change in visual sampling.
The endpoint is one measure of eye movements during walking, not a complete account of vision, cognition, gait, or daily function. Its meaning also depends on how the separate walking conditions and repeated observations were summarized. Those analysis details are not reported. The listed adverse-event counts are all zero, but the registry does not describe monitoring coverage or duration; these figures are not evidence that all possible harms were absent.
In short, the registry supports a description of the study population, measurement approach, and planned outcome focus. It does not support a conclusion about the size, direction, statistical significance, or practical importance of an observed outcome difference.
13. Why This Trial Matters Statistically
This study is statistically interesting because it places measurement of eye movements within walking tasks rather than describing visual sampling only in a stationary setting. The registry names several contexts that may challenge gait or attention, including dual-task walking, doorways, turning, and a visual cue. It also identifies cognition as a topic in the study title and defines cognitive eligibility thresholds for the two groups. These features make the definition of the measurement and the handling of task conditions central to interpretation.
The primary outcome is a continuous rate, while the secondary outcomes include other continuous gait and eye-movement measures. In general, a study with several related outcomes must distinguish its primary question from secondary or exploratory questions and explain how multiple comparisons are handled. The registry lists 27 outcome measures but does not report an analysis plan or numerical results. That leaves readers unable to determine which contrasts were tested, how repeated condition measurements were treated, or how uncertainty was quantified.
The non-randomized comparison also illustrates a basic distinction between describing an association and estimating a causal effect. The registry does not state allocation and characterizes the comparison as non-randomized. Group differences could therefore reflect factors besides Parkinson’s disease status, and the record does not describe adjustments intended to address this issue. The cognitive thresholds and unreported matching procedure are relevant design details when considering how comparable the groups may be.
Finally, the record demonstrates why an endpoint description is not a substitute for results. It identifies the mean and standard deviation as the intended summary format and names the measurement devices, but does not report the outcome estimates or their precision. Without those quantities, statistical interpretation remains limited to the design and measurement questions, not the magnitude or reliability of a finding.
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 most direct limitation for interpreting the registry record is that it contains no numerical results for the primary or secondary outcomes. It lists 27 outcome measures and zero analyses, but does not report group summaries, effect estimates, confidence intervals, or p-values. The direction and precision of an outcome comparison therefore cannot be assessed.
The study is described as a non-randomized comparison, with allocation not stated. The record does not explain participant recruitment, group formation, or the procedure used to make the older adults age-matched. It also does not report covariate adjustment. The Parkinson’s disease group and older-adult group have different MoCA eligibility thresholds, which is relevant when interpreting cognitive characteristics and potential group comparability.
Several measurement and analysis details are absent. Although the primary endpoint is described as mean saccade frequency measured with EOG and a Dikablis mobile eye-tracker, the record does not explain how signals were processed, how repeated measures across walking conditions were summarized, or how unusable recordings were handled. It does not report condition-specific estimates, outcome-specific sample sizes, or the number of participants contributing valid measurements. The analysis model and its assumptions are also not stated.
The registry identifies numerous outcome measures but does not report how multiplicity was addressed or whether the analysis plan distinguished confirmatory from exploratory comparisons. Missing-data methods, analysis populations, and sensitivity analyses are not reported. The adverse-event figures are recorded as zero, but monitoring procedures and the period covered are not described. These limitations constrain interpretation of both outcomes and safety reporting; they do not, by themselves, establish that a particular bias or problem occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Visual Function During Gait in Parkinson's Disease: Impact of Cognition and Response to Visual Cues — NCT02610634.
- Registry record last updated 2017-10-23; status last verified 2017-09.
- Results first posted 2017-01-30.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry describes a completed, non-randomized study of visual sampling during gait in people with Parkinson’s disease and older adults, with an enrollment of 100. The primary endpoint is mean saccade frequency during gait, measured using EOG and a Dikablis mobile eye-tracker during several walking conditions. Secondary outcomes include gait parameters and other measures of saccades.
The Parkinson’s disease group was described as at least 50 years old, without dementia, and with a MoCA score of 21 or higher. The older-adult group was described as age-matched, at least 50 years old, cognitively intact, and with a MoCA score of 26 or higher. Allocation was not stated. The registry record reports no numerical outcome results or analyses, and does not describe the analysis plan, missing-data methods, or multiplicity handling. Serious and other adverse events, and deaths, are recorded as zero in both groups.