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 Telemedicine Intervention to Improve Physical Function (NCT01639469), a randomized na study. The primary outcome is Total Falls During the 1-year Follow-up.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01639469 |
| Phase | NA |
| Condition | Parkinson's Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 169 |
| Arms in the primary outcome | 2 |
| Lead sponsor | VA Office of Research and Development |
| Results posted | Yes |
2. Clinical Question
Population
People with Parkinson’s disease. The registry record reports an enrollment of 169. For the primary fall outcome, 2 participants who were not analyzed were excluded because of early loss to follow-up and had no fall data collected.
Intervention
Structured exercise instruction by smartphone. The intervention is described as structured exercise, delivered as a behavioral program.
Comparator
A lifestyle exercise program taught via smartphone. This was also a behavioral program. The primary analysis compares the structured exercise group with the lifestyle exercise group.
Primary question
How did the total count of self-reported falls over follow-up of up to 1 year compare between the two exercise groups? Falls were collected weekly and totaled over the follow-up period. The reported analysis used negative binomial regression and expressed the comparison as an incidence rate ratio.
3. Trial Design
The registry record describes a randomized, single-masked, parallel-group trial. Participants were assigned to structured exercise instruction by smartphone or a lifestyle exercise program taught via smartphone. Both interventions are categorized as behavioral. The registry lists Parkinson’s disease as the condition and reports an enrollment of 169.
The study began in 2013-01, had primary completion in 2016-03, and is recorded as completed. The registry lists the phase as NA. The brief summary describes a one-year in-home exercise program and identifies falls, strength, and quality of life as areas of interest. The posted primary outcome, however, is total falls during the 1-year follow-up. The registry record does not report posted secondary outcome analyses.
The primary outcome population differs in its reported counts from the safety population: the fall analysis reports 88 participants in the structured exercise group and 79 in the lifestyle exercise group, while the serious adverse event figures use at-risk counts of 89 and 80. These are the counts recorded for their respective analyses; the registry record does not explain the difference in analysis populations.
The record identifies the VA Office of Research and Development as sponsor. It does not report further details about the randomization procedure, the masking procedure, or how participants and study staff were assigned or kept unaware of group assignment. Those details should not be inferred from the design labels alone.
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 | Structured Exercise | Lifestyle Exercise |
|---|---|---|
| STARTED | 89 | 80 |
| COMPLETED | 84 | 77 |
| NOT COMPLETED | 5 | 3 |
Reasons for not completing this period:
| Reason | Structured Exercise | Lifestyle Exercise |
|---|---|---|
| Death | 4 | 2 |
| Lost to Follow-up | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: 2 participants not analyzed were excluded due to "early loss to follow-up" and had no fall data collected.
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 | Structured Exercise | Lifestyle Exercise | Total |
|---|---|---|---|---|
| Participants analysed | 89 | 80 | 169 | |
| Age, Continuous | years | 71.5 (SD 9.4) | 72.7 (SD 9.8) | 72.1 (SD 9.6) |
| Sex: Female, Male: Female | Participants | 2 | 2 | 4 |
| Sex: Female, Male: Male | Participants | 87 | 78 | 165 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Total Falls During the 1-year Follow-up, measured over up to 1 year.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Total count of falls |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the total count of falls during follow-up of up to 1 year. The registry describes self-reported falls collected weekly and totaled over the follow-up period. Thus, the endpoint is a count accumulated over follow-up, rather than a measure of the time to a first fall or the number of participants who experienced at least one fall.
Fall counts are useful for representing recurrent events: a participant can contribute more than one fall. A count outcome therefore retains information about repeated events that a yes-or-no outcome would not capture. In this trial, the posted totals are 1026 falls in the structured exercise group and 1861 in the lifestyle exercise group. These are group totals, not individual-level counts or rates, and they do not by themselves account for differences in follow-up or the distribution of events across participants.
The record says 2 participants were not analyzed for this endpoint because of early loss to follow-up and had no fall data collected. Their missing fall data mean they could not contribute an observed fall count to the reported endpoint analysis. The registry record does not describe an imputation procedure or further details about how follow-up duration was handled in the model.
In general, a recurrent-event count can be analyzed with a count regression model that accounts for variability in the counts. The posted analysis used negative binomial regression and reported an incidence rate ratio.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary analysis reports an incidence rate ratio of 0.39 for structured exercise compared with lifestyle exercise, with a 95% confidence interval from 0.22 to 0.68 and p < 0.001. The sponsor’s analysis labels this comparison as superiority. The estimated ratio is below 1, so the model’s estimated fall rate is lower for structured exercise than for lifestyle exercise under the reported comparison.
The confidence interval describes uncertainty around the estimated ratio under the model. Its reported range is compatible with a range of lower rates in the structured exercise group, rather than a single precisely known value. The interval does not include 1, and the reported p-value is small; these are features of the posted statistical result, not proof that the estimate is free of bias or that the same effect would occur in other settings.
The raw outcome totals were 1026 falls among 88 participants in the structured exercise group and 1861 falls among 79 participants in the lifestyle exercise group. These totals provide descriptive context but are not a substitute for the model-based comparison. They cannot establish how falls were distributed among participants, and no unadjusted rate should be inferred from the totals alone.
The outcome is self-reported and accumulated over follow-up of up to 1 year. The record does not give individual follow-up time, a detailed missing-data analysis, or information about adherence to either program. These omissions limit what can be concluded about the relationship between the assigned programs and observed falls, including whether any differences reflect participation, reporting, or follow-up patterns.
The registry record reports one primary outcome measure and one analysis. It does not report secondary outcome analyses. The result therefore addresses the posted comparison for total falls, not the other outcomes described in the brief summary. It also does not establish effects beyond the recorded follow-up period.
9. Statistical Methods Explained
The primary outcome is a count: the total number of falls recorded over follow-up of up to 1 year. The registry reports weekly self-reports totaled across follow-up. The posted analysis used negative binomial regression, with the result expressed as an incidence rate ratio. This is a model-based comparison of the fall outcome between the two randomized groups.
What does a negative binomial model do?
General explanation: Count data often vary more than a simple model would expect if all participants had similar event rates. This extra variability is called over-dispersion. A negative binomial model allows for over-dispersion, making it a common option for count outcomes. The registry record does not report a dispersion estimate or explain the model-selection process, so the reason this model was chosen is not reported in the registry record.
The model’s incidence rate ratio compares the modeled event rate for one group with that for the reference group. Here, the reported ratio is 0.39, comparing structured exercise with lifestyle exercise. A ratio of 1 would represent equal modeled rates; a ratio below 1 indicates a lower modeled rate in the first group for this comparison. The registry provides the ratio but does not report further model details, such as covariates or an offset for follow-up time.
How should the confidence interval be read?
General explanation: A confidence interval communicates the precision of an estimate under the assumptions of the analysis. The reported 95% confidence interval is 0.22 to 0.68. It conveys uncertainty around the estimated incidence rate ratio; it is not a range of individual participants’ outcomes and does not guarantee that the true value lies in the interval. Its interpretation depends on the model and analysis assumptions.
The reported p-value is p < 0.001. General explanation: A p-value measures how incompatible the observed data are with a specified null hypothesis under the statistical model. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. The registry record does not report additional details of the hypothesis test beyond the stated analysis and result.
What does the raw count add?
The posted group totals are 1026 falls for structured exercise and 1861 for lifestyle exercise. The corresponding endpoint analysis counts are 88 and 79 participants. These descriptive figures show the event totals and group sizes used in the endpoint record, but do not reveal whether events were concentrated among a few participants or distributed across many. Nor do the totals alone describe person-time at risk. The model-based incidence rate ratio is the reported inferential comparison; a separate recalculated unadjusted comparison is not estimable from the posted summary statistics for this count outcome.
General explanation: Repeated events from one participant are not necessarily statistically independent. Count regression can model the number of events while allowing for variation between participants, but the details of how repeated events and follow-up were handled depend on the specified model. Those details are not reported in the registry record.
What are the planning illustrations?
Any sample-size planning illustrations associated with the posted results are not observed power and are not the trial’s original design calculations. The record describes them as illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. Such calculations are conditional on their assumptions and are not evidence about the probability that the trial detected an effect. The registry record does not report the trial’s own sample-size justification or planning assumptions.
More broadly, the record does not report whether there were interim analyses, a prespecified statistical analysis plan, or adjustment for multiple testing. The absence of those details should not be filled in by assuming what is customary. The posted inferential result can be described as reported, while those elements of its analysis context remain unknown.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Negative Binomial Regression | Incidence Rate Ratio 0.39 | 0.22 to 0.68 | < 0.001 |
The registry reports the sponsor’s primary analysis as negative binomial regression, with an incidence rate ratio of 0.39, a 95% confidence interval from 0.22 to 0.68, and p < 0.001. The analysis is labeled as a superiority comparison of structured exercise with lifestyle exercise.
A separate simple unadjusted re-calculation from posted summary statistics is not estimable for this count outcome. The available group totals and participant counts do not provide the information needed to reproduce the model-based incidence rate ratio. Consequently, there is no recalculated estimate to compare numerically with the sponsor’s result. The record does not indicate a discrepancy between the sponsor analysis and a recalculation.
The sponsor’s model-based analysis is therefore the inferential result to describe. Its interpretation remains subject to the information available about the model, endpoint collection, and analysis population. In particular, model details beyond the negative binomial method, missing-data handling, and the rationale for the analysis choices are not reported in the registry record.
11. Multiplicity, Missing Data and Analysis Populations
The registry record reports one primary outcome measure and one analysis: total falls during follow-up of up to 1 year, analyzed using negative binomial regression. It reports no posted secondary outcome analyses. The brief summary mentions falls, strength, and quality of life as areas of interest, but the posted results described in the record concern total falls. No inference about strength or quality of life can be drawn from this primary analysis.
The record does not report whether the outcome and analysis were selected in a prespecified statistical analysis plan, whether there were interim analyses, or whether any adjustment for multiple testing was planned or used. It is therefore not possible to assess from the registry record whether the reported p-value was adjusted for other analyses or outcome choices. The reported p-value should be read as the value attached to the posted primary analysis, without assuming an unreported multiplicity procedure.
For the fall outcome, the record states that 2 participants were not analyzed because of early loss to follow-up and had no fall data collected. It does not report a method for imputing their outcomes or describe sensitivity analyses for missing data. Their absence could matter if missingness was related to fall experience, but the record does not provide enough information to assess that possibility.
The analysis counts are 88 for structured exercise and 79 for lifestyle exercise. The safety at-risk counts are 89 and 80, respectively. The registry does not explain the difference between these reported populations, or provide a broader account of which participants were included in each analysis. It also does not report whether the primary analysis followed an intention-to-treat principle. These population and missing-data details are relevant to interpretation, but should not be resolved by assuming an analysis approach that is not documented.
12. 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 |
|---|---|---|---|
| Structured Exercise | 4 | 89 | 4.5% |
| Lifestyle Exercise | 2 | 80 | 2.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Structured Exercise | 4 of 89 |
| Lifestyle Exercise | 2 of 80 |
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 |
|---|---|
| Structured Exercise | 0 of 89 |
| Lifestyle Exercise | 0 of 80 |
Most frequent serious adverse event terms
| Event term | Organ system | Structured Exercise | Lifestyle Exercise |
|---|---|---|---|
| Death | General disorders | 4 of 89 | 2 of 80 |
Serious events with the highest arm-level rate: death (4.5%).
The safety record reports serious adverse events among 89 participants at risk in the structured exercise group and 80 at risk in the lifestyle exercise group. It lists 4 affected participants in the structured exercise group and 2 in the lifestyle exercise group. The record identifies Death as the top serious adverse event term and reports 4.5% for that term.
The record also reports 0 other adverse events in each group and deaths of 4 and 2, respectively. These figures should be read as separate entries in the safety record, not added together: the record does not establish that event categories are mutually exclusive or explain their relationship. In particular, it does not provide case-level information or further detail about the classification of the deaths.
Safety counts describe what was recorded, not the cause of an event or whether it was related to an intervention. The registry record does not provide additional detail about event timing, severity beyond the serious-event designation, attribution, or exposure duration. The safety at-risk counts also differ from the group counts reported for the primary fall analysis; the reason is not reported in the registry record. These figures do not by themselves establish a comparative safety profile.
13. What the Result Does, and Does Not, Mean
The posted data show a model-based comparison of total self-reported falls between two smartphone-delivered exercise programs. The negative binomial regression estimate favors a lower modeled fall rate in the structured exercise group relative to the lifestyle exercise group: the incidence rate ratio is 0.39, with a 95% confidence interval from 0.22 to 0.68 and p < 0.001. The sponsor labels the analysis as a superiority comparison.
This result does not mean that every participant in one group had fewer falls, or that the same outcome would occur for each person. The endpoint is a group-level count of recurrent events, and the record does not describe how those events were distributed among individuals. The estimate is subject to uncertainty, as reflected by the confidence interval, and depends on the statistical model and the quality and completeness of self-reported follow-up.
The result concerns the primary fall outcome over follow-up of up to 1 year. It does not establish an effect on strength, quality of life, or outcomes beyond the recorded follow-up; those results are not reported in the registry record. The record also does not provide information about adherence, intervention uptake, or individual follow-up duration that would support further explanations of the observed comparison.
The trial’s randomized design is relevant to the comparison, but the registry record does not report enough detail to evaluate all aspects of implementation or analysis. In particular, the rationale for the model, missing-data procedures, and analysis population beyond the stated counts are not reported. The result should therefore be read as the posted estimate and its precision, not as a complete account of the evidence or a recommendation about care.
14. Why This Trial Matters Statistically
This trial illustrates why recurrent-event outcomes need to be distinguished from simple participant-level outcomes. Total falls count repeated events over follow-up, so a participant may contribute more than one event. Reporting the event total alongside a model-based comparison makes clear that the statistical question concerns a count process, not merely whether a participant ever fell.
It also demonstrates the role of a count regression model in a clinical trial report. Negative binomial regression can allow for over-dispersion, a general feature of count data in which observed variation exceeds what a simpler count model expects. The registry reports this method and an incidence rate ratio, but does not report the diagnostics or modeling details needed to evaluate that choice further.
The difference between descriptive totals and an inferential estimate is important. The group totals and participant counts provide context, whereas the reported incidence rate ratio is the model-based comparison. Without individual-level data and further model details, a reader cannot reproduce that estimate from the summary figures alone. The uncertainty interval is therefore essential to reporting the magnitude and precision of the sponsor’s result.
Finally, the record highlights the importance of documenting analysis populations and missing data. The fall outcome and safety entries use different reported counts, and early loss to follow-up left participants without fall data. The registry does not explain all of these details. Clear reporting of such information helps readers understand the scope of an estimate without treating an observed group comparison as a complete account of every outcome or analysis choice.
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 primary endpoint relies on self-reported falls collected weekly. The registry record does not describe how reports were checked, how missed weekly reports were handled, or whether participants’ reporting differed between groups. The outcome is therefore subject to the limitations of the recorded reporting process.
Two participants were excluded from the primary analysis after early loss to follow-up and had no fall data collected. The registry does not report why they were lost, how much follow-up they had, or whether any sensitivity analysis assessed the effect of missing outcomes. This leaves uncertainty about how the missing data may affect the comparison.
The posted summaries do not include individual fall counts, distributions, or individual follow-up times. The registry also does not report covariates, model diagnostics, an exposure offset, or other details of the negative binomial regression. A separate unadjusted re-calculation is not estimable from the reported summary statistics, so the sponsor’s model-based estimate cannot be independently reproduced from these figures alone.
The record does not report adherence to the exercise programs, the amount of exercise completed, or details of intervention delivery beyond smartphone instruction. It also does not report further details about randomization or masking. These gaps restrict assessment of how the interventions were implemented and how the design features operated in practice.
Finally, no secondary outcome analyses are posted, despite the brief summary’s mention of strength and quality of life. Multiplicity procedures, interim analyses, and the trial’s sample-size justification are not reported in the registry record. These limitations do not change the result that was posted, but they narrow what can be concluded from it.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Telemedicine Intervention to Improve Physical Function — NCT01639469.
- Registry record last updated 2017-06-23; status last verified 2017-06.
- Results first posted 2017-06-23.
- 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.
19. Record Summary
This completed randomized, single-masked, parallel-group trial compared smartphone-delivered structured exercise with a smartphone-taught lifestyle exercise program in people with Parkinson’s disease. The registry reports an enrollment of 169, a start date of 2013-01, and primary completion in 2016-03.
The primary endpoint was total self-reported falls during follow-up of up to 1 year. Falls were collected weekly and totaled. The posted negative binomial regression analysis reported an incidence rate ratio of 0.39, with a 95% confidence interval from 0.22 to 0.68 and p < 0.001, for structured exercise compared with lifestyle exercise.
The endpoint analysis excluded 2 participants with early loss to follow-up and no fall data. The record does not report secondary outcome analyses, detailed missing-data methods, or full model specifications. Safety entries report serious adverse events and deaths separately, with at-risk counts that differ from the endpoint analysis counts; the reason is not reported in the registry record.