In-home Cycling for Individuals With PD: Feasibility: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for In-home Cycling for Individuals With PD: Feasibility (NCT04300023), a randomized na study. The primary outcome is Adherence: Percentage of Sessions Completed.

2. Clinical Question

The registry describes a study of whether social support during in-home cycling is associated with exercise outcomes for individuals with Parkinson disease. Its stated interests include exercise frequency and duration, quality of life, and overall activity level. The posted primary outcome focuses more narrowly on adherence: the percentage of prescribed cycling sessions completed during the active intervention.

The study is randomized and described as a crossover. The registry says that 6 participants in the solo cycling group crossed over to the social group. Thus the posted group counts do not represent two wholly separate sets of people: the social-group result includes 12 participants, while the solo-group result includes 6. The record does not report a formal estimate of the effect of social support, an uncertainty interval for a between-condition contrast, or a test of that contrast. The results therefore answer the descriptive adherence question by condition, but do not by themselves establish a causal difference between conditions.

3. Trial Design

NCT04300023 is a completed randomized study listed as a feasibility study of in-home cycling for individuals with Parkinson disease. Its design is described in the registry as a crossover model with no masking. The sponsor is the University of Wisconsin, Madison. The listed start date is 2021-08-25, the primary completion date is 2024-01-04, and the status is COMPLETED. The registry lists 13 participants enrolled.

Both conditions involved an exercise bike delivered to the participant’s home, fitted to individual needs, and installed in a safe location. In the Solo Cycling Control Group, participants received exercise recommendations and data-recording calls every 2-weeks. In the Social Cycling Group, cycling sessions involved social interaction with a research staff member, adding a social or community element. The sessions were described as lasting up to 30 minutes. These descriptions distinguish the conditions by the social interaction component; they do not establish that every participant completed the same number or duration of sessions.

The primary outcome covers up to 6 months of active intervention and is based on completed sessions divided by the prescribed number of sessions per protocol, which the registry gives as 72. The primary outcome population is described as 12 unique participants, including 6 who moved from solo cycling to the social group. The reported group counts are 6 for solo cycling and 12 for social cycling. Because of crossover, these counts should not be read as independent randomized groups with no participant overlap.

The registry does not report the randomization sequence, the timing of each condition, a washout period, or how period and sequence effects were handled. Those details matter when interpreting crossover results because a participant’s experience in one condition may be related to their results in another. The record also does not report masking beyond listing the study as unmasked, or a formal statistical plan for comparing the conditions. No phase is applicable, as the study is listed with phase NA.

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: All participants who started the solo cycling group crossed over to the social cycling group.

Before Crossover to Social Group

Reasons for not completing this period:

After Crossover to Social Group

Analysis population for the primary outcome, as defined in the registry: 12 unique participants, 6 solo cycling group crossed over to social group

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.

Population: One individual assigned to the social cycling group contracted COVID following the baseline assessment and withdrew prior to starting the intervention.

6. Primary Endpoint

The registry lists the primary outcome as Adherence: Percentage of Sessions Completed, measured over up to 6 months of active intervention.

The primary endpoint is titled “Adherence: Percentage of Sessions Completed.” It measures the total number of completed sessions as a percentage of the number prescribed by the study protocol. The registry specifies 72 prescribed sessions and an assessment period of up to 6 months of active intervention. In plain terms, the endpoint describes how much of the planned cycling schedule participants completed.

Adherence is used in a feasibility study because it describes participation in the assigned activity, rather than a health outcome. It can indicate whether participants engaged with the prescribed sessions under the study conditions. It does not directly measure cycling intensity, fitness, disease progression, or quality of life. The registry separately identifies time per session and adverse events among secondary outcomes, but does not post results for those measures in the information described in the record.

The endpoint is reported as a mean with a full range for each condition. The solo cycling result is 38.0, with a range from 7.0 to 75.0; the social cycling result is 94.6, with a range from 88.9 to 98.6. The registry labels the unit as percent sessions completed. A range describes the lowest and highest reported values, not the distribution of all participant results. The record does not provide participant-level observations or an uncertainty interval for either mean.

Adherence can help characterize the practical conduct of an intervention, but it is not a direct estimate of the effect of social interaction. In this crossover study, a formal condition comparison would need to account for the design and participant overlap. Such an analysis is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean summarize?

General explanation: A mean combines observed values into a single measure of their arithmetic average. It can be useful for describing a group, but it does not show the shape of the distribution or how many observations fall near that average. The endpoint results are reported as means: 38.0 for solo cycling and 94.6 for social cycling. The registry also reports full ranges for both conditions. Those measures provide different descriptive information and should be read together rather than treated as interchangeable.

The mean does not automatically describe a typical participant well in every dataset. If observations vary widely or are concentrated unevenly, individual results may differ from the mean. Here, the solo range extends from 7.0 to 75.0, and the social range extends from 88.9 to 98.6. The record does not include individual values, so it is not possible to assess the distribution in more detail from the registry summary alone.

What does the full range tell the reader?

General explanation: A full range gives the smallest and largest observed values in the summarized data. It is a descriptive measure of spread, not an estimate of the precision of the mean. It also does not reveal whether most values are close together or whether observations are distributed across the entire span. A confidence interval, by contrast, is designed to express uncertainty around an estimate under a statistical method and its assumptions. No confidence interval for the adherence mean or condition contrast is reported in the registry record.

Because the registry reports only the mean and full range for the primary endpoint, there is no posted standard deviation or other summary that would further describe variation around the mean. The range alone cannot be used to reconstruct participant-level results or a paired comparison.

Why does the crossover design matter?

General explanation: In a crossover design, participants may receive or experience more than one condition over time. Comparing conditions can then use within-person information, which may be useful because each participant can serve as their own reference. However, the analysis needs to account for the repeated observations and the order in which conditions occur. Period effects, carryover, and changes over time can affect interpretation. These are general methodological considerations, not claims about what occurred in this study.

The registry describes a randomized crossover and says that 6 participants crossed from the solo condition to the social condition. It does not report the condition sequence for all participants, the timing between conditions, or an analysis accounting for within-person data. The posted group means are therefore best interpreted as descriptive condition summaries, not as a complete crossover analysis. Treating the 6 and 12 group counts as unrelated samples would overlook the participant overlap described in the record.

What would an inferential comparison add?

General explanation: An inferential comparison estimates a contrast and quantifies uncertainty around it, using a statistical method suited to the design and outcome. A confidence interval can show a range of values reasonably compatible with the data and method; a test can assess the data against a specified null hypothesis. Neither is a substitute for evaluating the study design, measurement, and assumptions. The registry record reports no analyses and gives no inferential comparison for adherence. Therefore there is no posted confidence interval or p-value to interpret.

The lack of a reported analysis does not show that no analysis was conducted outside the registry. It means only that an analysis is not reported in the registry record. No statistical model, adjustment strategy, or treatment of repeated measurements is specified there.

Why might over-dispersion matter?

General explanation: Over-dispersion occurs when observed variability is greater than a statistical model expects. If a model assumes less variation than is present, its uncertainty estimates can be too small, making results appear more precise than they are. The concept is relevant to some kinds of outcome data and models, but the registry does not report an analysis of over-dispersion for this endpoint. The primary outcome is presented as a mean percentage with a full range, and the record does not identify a model that would allow an over-dispersion assessment. It would be inappropriate to claim that over-dispersion was present or absent.

How should planning calculations be read?

General explanation: Sample-size planning calculations describe the number of participants a hypothetical future study might require under specified assumptions. They are not observed trial outcomes, and they do not show the probability that this completed study detected an effect. The registry’s planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects expressed as fractions of the observed effect. Such figures, when presented, are planning illustrations rather than observed power.

Those assumptions describe a planning calculation, not the trial’s own design justification. The registry does not report a sample-size justification for the completed study. The planning illustration should not be used to imply that the observed result had a particular probability of statistical significance, or that the study was designed to detect a specified clinical difference.

What does the word “recalculated” mean?

General explanation: A recalculation from posted summary statistics is an unadjusted calculation based on the available summaries. It may not match a sponsor’s prespecified analysis, especially when the design involves repeated observations or other features that require adjustment. No recalculated comparison is reported in the registry record for this outcome, and the registry lists zero analyses. There is no reported discrepancy between a sponsor analysis and a recalculation to resolve.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and identifies two secondary outcomes: Time Per Session and Adverse Events. It does not report a multiplicity plan describing whether or how statistical testing across outcomes was controlled. Multiplicity matters when several outcomes or comparisons are tested because the chance of at least one apparently notable result can increase as the number of tests grows. This is a general statistical concern; the record does not state that a particular testing strategy was used.

The registry reports the primary adherence outcome as a mean and full range by condition, but no inferential analyses are posted. It lists zero analyses. The absence of posted analyses means there are no reported p-values or adjusted results to interpret; it does not establish what analyses may have been conducted outside the registry. A protocol-level analysis plan, including any hierarchy among endpoints, is not reported in the registry record.

Missing-data handling is also not reported in the registry record. The primary outcome population is described as 12 unique participants, while the enrollment is 13. The record does not explain the status of the remaining enrolled participant for this outcome, whether any session records were incomplete, how missing sessions were treated in the percentage, or whether participants with incomplete data were excluded. No assumption about missingness or imputation should be inferred from the posted means and ranges.

The analysis population is not described in enough detail to determine whether the results follow an intention-to-treat, per-protocol, or other approach. In a crossover study, it would also be relevant to know how participants who did not complete both conditions were handled and whether period-specific observations were included. These details are not reported in the registry record. The participant counts and the crossover description therefore support a descriptive reading, but not reconstruction of a full analysis population or analysis strategy.

11. 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 reports zero participants with serious adverse events among 6 participants at risk in the Solo Cycling Control Group and zero among 12 participants at risk in the Social Cycling Group. It also reports zero participants with other adverse events among 6 at risk in the solo group and zero among 12 at risk in the social group. The death count is 0 in each group. No serious adverse-event terms are listed.

These figures describe the event counts recorded in the registry for the groups and populations shown. They do not establish that no event of any kind occurred outside the registry’s reporting definitions or observation period. The record does not report detailed event definitions, the method of event collection, or the specific observation period for safety reporting. Those details are not reported in the registry record.

Zero recorded events in a small study is not equivalent to proof that an intervention has no safety risks. It also does not support a precise comparison of safety between conditions. The group counts involve crossover, so the condition populations should not be assumed to be independent sets of participants. The safety figures are best read as registry-reported counts, without extending them to a general conclusion about safety.

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

The main result is a difference in the descriptive adherence summaries: the registry reports a mean of 38.0 percent sessions completed in the Solo Cycling Control Group and 94.6 in the Social Cycling Group. The full range is 7.0 to 75.0 for solo cycling and 88.9 to 98.6 for social cycling. These results describe what was recorded for the study conditions; they do not, by themselves, estimate a causal effect of social interaction.

The crossover design and participant overlap are central to interpretation. Six participants moved from solo cycling to the social condition, and the primary outcome population is described as 12 unique participants. The social-group count of 12 therefore should not be read as 12 people who were wholly separate from the 6 in the solo group. The record does not post a within-participant analysis or a formal adjusted contrast. The means alone cannot establish how much an individual’s adherence changed between conditions.

The endpoint concerns completion of prescribed sessions. It is a measure of participation, not a direct measure of physical activity intensity, quality of life, overall activity, or any other clinical outcome. Although the study description identifies those broader interests, the adherence result cannot substitute for their measurement. The registry lists Time Per Session and Adverse Events as secondary outcomes, but numerical secondary-outcome results are not reported in the registry record.

No confidence interval or p-value is reported for the primary outcome comparison. Consequently, the precision of a difference between conditions is not quantified in the posted results. The means and ranges are useful descriptive summaries, but they do not communicate the uncertainty that a formal estimate and interval would provide. Neither the range nor the size of the observed contrast should be mistaken for a measure of statistical significance.

The results are specific to this completed feasibility study, its participants, and its in-home cycling arrangements. The record does not report a sample-size justification or an inferential analysis designed to support broader effectiveness claims. The most defensible conclusion is limited to the posted adherence summaries and the reported study design. Any broader statement about the effect of social support or the experience of other populations would go beyond what the registry record reports.

13. Why This Trial Matters Statistically

This study illustrates why feasibility outcomes deserve a different interpretation from clinical efficacy outcomes. Adherence describes whether participants completed the sessions prescribed by a study. It can help characterize engagement with an intervention and the practical experience of delivering it, while not answering whether the intervention changes health or quality-of-life outcomes. Keeping those questions separate avoids treating participation as a proxy for clinical benefit.

The crossover format also highlights the importance of matching the analysis to the design. When participants contribute observations in more than one condition, those observations are linked within a person. A comparison that ignores that relationship may not represent the intended condition contrast or its uncertainty. The registry identifies crossover and participant overlap, yet does not post a formal comparison accounting for them. The descriptive results remain informative, but their role should not be overstated.

Another statistical lesson is that a mean and a range are not enough to reconstruct a full analysis. The mean conveys an average, and the range conveys the extremes. Neither provides a confidence interval or tells the reader the relationship between a participant’s results across conditions. Participant-level data or a suitable repeated-measures analysis would be needed to address those questions, and those details are not reported in the registry record.

Finally, the record separates what can be stated from what remains unknown. It reports enrollment, the condition descriptions, the primary outcome definition, descriptive adherence results, and adverse-event counts. It does not report a multiplicity strategy, missing-data approach, detailed analysis population, or inferential results. This distinction is useful for clinical researchers: registry summaries can support transparent description while still leaving important statistical questions unanswered.

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 primary limitation for interpreting the adherence result is the absence of a reported inferential comparison. The registry gives condition-specific means and full ranges, but no confidence interval, p-value, or model-based contrast. It is therefore not possible to assess the precision of a between-condition estimate from the registry record.

The study is described as a crossover, and 6 participants crossed from solo cycling to social cycling. The posted group counts are 6 for solo cycling and 12 for social cycling, with 12 unique participants identified in the primary outcome population. This overlap means the condition summaries are not independent-group results. The record does not report the condition sequence for all participants, how the crossover observations were analyzed, or whether period or carryover effects were considered.

The registry reports 13 enrolled participants but describes 12 unique participants in the primary outcome population. It does not explain this difference or state whether any data were missing, excluded, or unavailable. The method used to handle incomplete session records is not reported in the registry record. The record also does not provide participant-level adherence values or a standard deviation, limiting assessment of the distribution beyond the full range.

Other details that would affect interpretation are not reported: a sample-size justification, a prespecified statistical analysis plan, a multiplicity strategy, and a detailed analysis population. The study description includes interests in exercise frequency, duration, quality of life, and overall activity level, but numerical results for those measures are not reported in the registry record. The posted primary endpoint therefore addresses adherence, not those broader outcomes.

Finally, the study is a small feasibility study of in-home cycling among people with Parkinson disease. The registry does not provide enough information to judge how representative participants were of a wider population or how readily the findings would generalize to other settings. These limitations do not invalidate the descriptive results; they define the scope of what can be concluded from them.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: In-home Cycling for Individuals With PD: Feasibility — NCT04300023.
• Registry record last updated 2025-02-04; status last verified 2025-01.
• Results first posted 2025-02-04.
• 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.

18. Record Summary

NCT04300023 is a completed randomized crossover feasibility study of in-home cycling for individuals with Parkinson disease. The registry lists 13 participants enrolled, a study start date of 2021-08-25, a primary completion date of 2024-01-04, and the University of Wisconsin, Madison as sponsor. The study was unmasked and is listed with phase NA.

The primary endpoint is adherence, defined as completed sessions divided by 72 prescribed sessions, during up to 6 months of active intervention. The registry reports mean adherence of 38.0, with a full range of 7.0 to 75.0, for solo cycling, and 94.6, with a full range of 88.9 to 98.6, for social cycling. The primary outcome population is described as 12 unique participants, including 6 who crossed from solo to social cycling.

The registry does not report a formal inferential comparison, confidence interval, p-value, sample-size justification, or detailed missing-data and analysis-population methods. It reports zero serious adverse events, zero other adverse events, and zero deaths in both condition groups. These results are descriptive and should be interpreted in light of the crossover design and the limits of the posted statistical details.