Optimization and Multi-Site Feasibility of Yoga for Chronic Pain in People in YOGAMAT-II - Phase I: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Optimization and Multi-Site Feasibility of Yoga for Chronic Pain in People in YOGAMAT-II - Phase I (NCT04646148), a randomized na study. The primary outcome is Percent of Weeks Where Data on Amount of Yoga Personal Practice Were Collected.

2. Clinical Question

The study is a feasibility and preparation trial rather than a definitive test of clinical benefit. Its stated aims include establishing trial procedures and documenting feasibility at both sites, including recruitment, training yoga teachers to fidelity, assigning and delivering intervention components, running classes, and collecting follow-up assessments. Those aims provide context for interpreting the outcome: completeness of practice data was considered useful because it could help determine whether a more direct practice measure can be used in later research.

The registry identifies random allocation and a factorial model. In general, factorial designs assign combinations of components so that their effects can be examined in relation to one another. However, this record posts no inferential analysis of component effects. It therefore does not answer whether videos, individual sessions, texts, or incentives changed practice or data collection. The reported values describe small groups in this pilot, not a comparative estimate of clinical effectiveness.

3. Trial Design

The registry describes a completed, randomized, double-masked factorial Phase I pilot sponsored by Butler Hospital. It lists an enrollment of 20 and a study period beginning 2021-03-01, with primary completion on 2021-11-01. The planned setting was two opioid use disorder clinic sites; the brief summary states a target of n=10 at each site and a total n=20. The record does not report site-specific enrollment or whether the intended enrollment was achieved at each site.

Yoga classes were the behavioral intervention. Randomized groups varied across four optional support components: Personal Practice Videos, One-on-One individual sessions with a Yoga Instructor, prompting Text messages, and financial Incentives to attend yoga classes. The group descriptions specify which components were and were not received. This component-based structure is consistent with the registry’s factorial model designation, but the exact allocation procedure, blocking or stratification, and implementation details are not reported in the registry record.

The record labels masking as double. It does not identify which people were masked or explain how masking was maintained. Because the intervention includes observable classes and support activities, the label alone does not establish which participants, instructors, assessors, or analysts knew group assignments.

The stated purpose was to establish procedures and document feasibility before a fully powered optimization trial. The listed feasibility aims concern recruitment, teacher training to fidelity, randomization and delivery of components, class operation, and follow-up data collection. The registry does not report quantitative results for those feasibility aims in the posted outcome fields.

There are no posted inferential analyses for the primary outcome, and no secondary outcome measures are posted. The trial’s phase is listed as NA in the registry, while the title identifies it as Phase I. The protocol, prespecified analysis plan, and justification for enrollment size are not reported in the registry record. The study’s pilot framing is therefore important: the small group summaries can describe what was observed, but the record does not establish that the trial was designed to estimate precise differences among component combinations.

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.

Only the first 6 of 16 groups are shown.

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.

Population: This was a pilot study. We planned ahead of time that some arms would not be populated.

Only the first 6 of 17 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Percent of Weeks Where Data on Amount of Yoga Personal Practice Were Collected, measured over 3 months.

The primary endpoint is the percentage of weeks during which data on the amount of personal yoga practice were collected. The follow-up timeframe is 3 months, and the description states that 12 weeks were possible. The registry reports the endpoint as a mean with standard deviation. The measure concerns whether practice information was obtained over the weeks, not how much yoga participants actually practiced. A participant could have data recorded for a week without that percentage conveying the duration, frequency, or quality of practice.

The registry explains why this outcome was selected: these data were considered important for deriving the primary outcome in the next phase, described as total amount of yoga practice. In a pilot focused on trial preparation, the completeness of measurement can help assess whether follow-up procedures capture information needed for a later study. It is therefore a process or measurement outcome, not a direct clinical outcome such as pain severity or opioid use.

The posted group summaries include means ranging from 8.3 to 100.0 percentage of weeks, with several groups reporting 100.0. Group sizes are very small, including groups with only one or two participants, and two groups have no participants by design. Standard deviations are reported for some groups, while confidence limits are not posted. These summaries show that the recorded data completeness varied among the small groups, but they do not establish which intervention component caused any variation.

The measure’s interpretation depends on the collection process. Missing practice information may reflect data collection, follow-up, participant reporting, or other factors; the registry does not distinguish among these possibilities. The endpoint is useful as an indication of whether data were collected, but alone it does not establish actual practice behavior or clinical benefit.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean summarize?

General statistical explanation: A mean is the average of the observed values in a group. For this endpoint, each value represents a percentage of possible weeks with personal-practice data collected. A group mean of 100.0 indicates that the observed participants in that group had data collected for all possible weeks on average. It does not describe the amount of yoga practiced, and it does not guarantee that every participant had the same experience unless the participant-level values are known.

The registry reports standard deviations as the measure of spread. In general, a standard deviation describes how dispersed individual observations are around their group mean. A standard deviation of 0.0 means there was no observed variation among the values contributing to that summary. When a group contains only one participant, there is no meaningful information about between-participant variability; the registry posts 0.0 for several such summaries. Small groups make both means and spread estimates unstable as descriptions of a larger population.

Why does the factorial structure matter?

General statistical explanation: A factorial trial studies combinations of intervention components. Rather than comparing only one complete treatment package against one control package, a factorial design can be used to estimate component effects and, when planned, whether effects depend on combinations of components. Here the components are Personal Practice Videos, One-on-One sessions with a Yoga Instructor, prompting Text messages, and financial Incentives to attend classes. The listed groups represent different combinations of those components, including groups with components absent.

The structure does not itself guarantee that component effects can be estimated. That depends on the allocation, sample size, observed data, and analysis plan. In this record, some groups have no participants by design, and the remaining groups have very small counts. The registry posts no inferential analyses, so it does not estimate component effects or interactions. General factorial-design principles should not be mistaken for analyses that this trial actually reported.

What do confidence intervals contribute?

General statistical explanation: A confidence interval gives a range of values compatible with an estimate under a specified statistical procedure and its assumptions. It communicates uncertainty around the estimate; it is not a guarantee that the true value lies within a particular interval. The registry does not post confidence intervals for the primary endpoint. Without them, readers cannot use this record to assess the interval-scale precision of each group mean.

Even if intervals had been reported, intervals from groups with very few participants would generally be expected to be wide, because the data contain little information about the population mean. That is a general statistical consideration, not a calculated interval for this trial. No confidence limits are reported for any primary outcome group.

What can the posted comparisons support?

General statistical explanation: A comparison between group means requires an estimate of the difference and a measure of its uncertainty. A causal interpretation also relies on the trial design being implemented as intended and on an appropriate analysis. The record supplies group-level descriptive means and standard deviations, but does not post pairwise differences, tests, confidence intervals, or adjusted estimates. It also identifies the no-component group as empty in the outcome results. Thus, the record does not support a numerical comparison of the combinations or a conclusion about which component influenced data collection.

The planning illustration assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. These assumptions are for planning illustrations, not a description of the trial’s own statistical plan. The record does not report the trial’s sample-size justification. Since the posted results do not provide an estimable two-arm comparison for this continuous endpoint, there is no endpoint-specific planning estimate available in the registry record.

General statistical explanation: A sample-size calculation estimates how many participants a future study might need under specified assumptions about the target effect, variability, allocation, and type I error. It is not a measure of the power actually achieved by an already completed trial. Small observed groups are not evidence of low or high observed power, and observed power should not be inferred from the posted group means.

How should variation and incomplete observations be considered?

General statistical explanation: Over-dispersion means observed variation is greater than a model assumes. When that occurs, standard errors and tests based on the narrower variation assumption can understate uncertainty. The primary endpoint is continuous and the registry reports standard deviations, but no inferential model is posted, so over-dispersion cannot be assessed from an analysis in the record. The groups are also too small to support a stable assessment of distributional shape.

The endpoint itself concerns collection of data across possible weeks. It is therefore important to distinguish a week with no collected practice information from a week in which practice did not occur. The registry defines the outcome around whether data were collected, but does not provide reasons for uncollected data or describe any imputation, missing-data model, or sensitivity analysis. General methods for missing data cannot resolve that information gap without participant-level detail and a stated analysis plan.

The registry reports zero analyses and zero posted secondary outcomes. It does not state how multiplicity across the factorial components or outcome measures was handled, whether interim analyses were planned, or which analysis population was intended. Such choices can affect statistical inference, but their details are not reported in the registry record. The descriptive summaries should therefore be kept separate from unreported inferential methods.

10. Multiplicity, Missing Data and Analysis Populations

The registry posts no inferential analyses for the primary endpoint and no secondary outcome results. It does not report hypothesis tests or confidence intervals, nor does it state how comparisons among the intervention components or combinations would be prioritized. A factorial structure can create multiple potential component and interaction questions; the record does not describe any multiplicity adjustment or other strategy for interpreting multiple tests. The protocol’s statistical plan is not reported in the registry record, so it is not possible to determine whether such procedures were planned but not posted.

Missingness has a particular role in this study because the primary endpoint is the percentage of weeks with personal-practice data collected. The posted group means describe this collection measure, but the registry does not identify reasons that data were not collected in a given week. It does not report imputation, a missing-data model, sensitivity analyses, or participant-level patterns of follow-up. Consequently, the summaries cannot show whether uncollected information was associated with attendance, practice, intervention assignment, or other factors.

The outcome group listing includes two groups with no participants and states that no one was assigned to group 1 or 3 by design. Their absent estimates should not be interpreted as missing observations from enrolled participants. The registered no-component group also has no participants in the primary outcome results. The record does not explain whether this reflects allocation as intended beyond the stated design information.

The registry does not identify an analysis population, such as all randomized participants or participants with available outcome data. It does not report exclusions or deviations from assigned components. The listed arm counts and summaries are descriptive, but the record does not specify the participant-level rules used to form each analysis set. These omissions limit assessment of how the posted values relate to all randomized or enrolled participants.

Interim analyses, multiplicity procedures, missing-data handling, and analysis-population definitions are not reported in the registry record. These are reporting gaps, not evidence that a particular procedure was or was not used.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event listing separates serious events from other adverse events and reports how many participants were at risk and how many were affected in each intervention group. Across the listed groups, the number of participants affected by serious adverse events is 0, and deaths are reported as 0. The record lists no serious adverse event terms. These are the posted counts; they should not be interpreted as proof that risk is absent.

Other adverse events are reported for some small groups. For example, one group with No Video/No One-on-One/Yes Text/Yes Incentive has 1 participant at risk and 1 affected by an other adverse event. Another group, Yes Video/Yes One-on-One/Yes Text/No Incentive, has 2 at risk and 2 affected. Other listed groups have different counts, including groups with no affected participants. The group denominators are small, so the counts alone do not provide precise estimates of event rates or support reliable comparisons across combinations.

These summaries are counts, not adjusted comparisons. The record does not provide event descriptions for the other adverse events in the listed terms, and it does not report an analysis relating events to particular components. A zero count in a small group means no affected participants were recorded there in this listing; it does not establish that the intervention combination carries no risk. No treatment recommendation or safety conclusion can be drawn from these descriptive figures alone.

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

The results show that the registry recorded different levels of completeness for weekly personal-practice data across the small intervention-combination groups. Several group means are 100.0 percentage of weeks, while other reported means include 8.3, 12.5, 58.3, and 62.5. These values are useful as pilot descriptions of the collected endpoint, particularly because the stated next-phase goal is to derive a measure of total yoga practice.

The results do not show how much yoga participants practiced. The endpoint measures whether practice data were collected, not practice duration or frequency. Nor do the posted results measure change in chronic pain or opioid use. Those outcomes cannot be inferred from data completeness.

The summaries also do not establish whether a particular support component improved data collection. The groups have very few participants, two groups are empty by design, the no-component group has no outcome estimate, and no inferential comparisons are posted. Differences among the displayed means may reflect the observations of individual participants or other variation; the record does not quantify uncertainty with confidence intervals or explain causes of missing weekly data.

The trial’s stated aims extend beyond the primary endpoint to recruitment, teacher training, intervention delivery, class operation, and follow-up assessment. The registry record describes those aims but does not post quantitative findings for each feasibility target. The primary outcome summaries alone therefore cannot establish whether all procedures were feasible at both sites or ready for a later optimization trial.

In statistical terms, this is a small feasibility dataset that can motivate measurement and design decisions, not a definitive estimate of a population effect. A later study would need a clearly specified analysis plan and enough observations in the relevant groups to estimate component effects with useful precision. The registry record does not report those later results, and the pilot findings should not be generalized beyond what the posted descriptive data support.

13. Why This Trial Matters Statistically

This trial illustrates a central statistical challenge in pilot and factorial research: a design can include several intervention components, but the ability to learn about component effects depends on sufficient observations in the combinations being compared. Here, the record lists many combinations, yet the total enrollment is 20 and the primary outcome groups contain at most two participants each. Two groups have no participants by design, and the group receiving none of the four components has no primary outcome estimate. The factorial label alone cannot overcome sparse data.

The selected endpoint also highlights the difference between measuring an outcome and measuring the quality of its collection. The percentage of weeks with practice information is relevant to planning a later measure of total practice, but it is not interchangeable with actual yoga practice. Clearly distinguishing these concepts prevents a process measure from being interpreted as a behavioral or clinical result.

The registry’s stated feasibility aims cover recruitment, instructor training, component delivery, classes, and follow-up assessment. Those aims are important in a multi-site pilot because operational procedures can affect whether a later study can produce interpretable data. Yet the posted outcome summaries address only data collection for personal practice; the registry does not provide quantitative results for the other feasibility aims. That gap shows why pilot reporting benefits from explicit operational criteria and results for each aim.

Finally, this record demonstrates the value of separating descriptive evidence from inference. Group means can describe what was observed, but without adequate group sizes, uncertainty estimates, and a reported analysis plan, they do not establish comparative effects. For clinical researchers, that distinction is essential when using pilot results to refine measurement or plan a larger study.

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 outcome groups are very small, with only one or two participants in groups where results are reported. This makes group means sensitive to individual observations and limits the usefulness of standard deviations as estimates of population variability. Two groups have no participants by design, and the group with no videos, no individual sessions, no texts, and no incentives has no primary endpoint estimate. Comparisons with that group are unavailable.

The registry posts no confidence intervals, hypothesis tests, adjusted estimates, or component-effect analyses. It also reports no secondary outcome results. The descriptive summaries cannot establish whether differences between groups reflect intervention components, random variation, or other factors. The record does not report the planned statistical analysis, multiplicity strategy, sample-size justification, or intended analysis population.

The outcome measures collection of personal-practice information rather than amount of practice. Reasons for weeks without collected data are not reported, and no missing-data procedures or sensitivity analyses are described. The summaries therefore cannot distinguish incomplete collection from lack of practice or other causes of missing information.

The record identifies a two-site pilot and outlines feasibility objectives, but it does not report site-specific outcome summaries or quantitative results for the broader objectives, such as recruitment, teacher fidelity, delivery of components, class operation, and follow-up assessments. The double-masking designation is not accompanied by details about who was masked. The registry record also does not report protocol-level implementation details or interim-analysis plans.

These limitations mean the posted results are best read as sparse descriptive information about one measurement outcome. They do not support precise generalization to a wider population or causal conclusions about the intervention components.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Optimization and Multi-Site Feasibility of Yoga for Chronic Pain in People in YOGAMAT-II - Phase I — NCT04646148.
• Registry record last updated 2022-09-14; status last verified 2022-08.
• Results first posted 2022-09-14.
• 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

The registry record describes a completed randomized, double-masked factorial pilot of yoga classes for people in treatment for opioid use disorder with chronic pain. Enrollment is listed as 20, with a planned two-site approach and n=10 at each site. The study period is listed from 2021-03-01 to primary completion on 2021-11-01.

The primary outcome is the mean percentage of weeks during 3 months in which personal-practice data were collected. Group means vary, but group sizes are very small; two groups have no participants by design, and no inferential analyses or secondary outcome results are posted. The registry’s aims include establishing procedures and documenting feasibility, but quantitative findings for the broader feasibility aims are not reported in the registry record.

The posted data are descriptive and do not establish comparative effects of videos, individual yoga sessions, text messages, or incentives. They also do not measure total yoga practice, pain outcomes, or opioid use outcomes.