Feasibility of Pain Informed Movement for Knee OA: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feasibility of Pain Informed Movement for Knee OA (NCT04954586), a na na study. The primary outcome is Acceptability of Content.

2. Clinical Question

The study asks whether a pain-informed movement program accompanied by education is feasible for people with knee osteoarthritis, and whether participants find its content acceptable. The intervention is described as an in-person group exercise program, with movement sessions and instructions for home practice. Its stated purpose is to inform a pilot and feasibility randomized controlled trial before a multisite trial assessing effectiveness.

The primary endpoint concerns acceptability of content. Participants rated how useful they found the treatment on a Likert scale from 1 to 5, and the registry defines the relevant result as the count reporting a rating greater than 4/5. This asks about participants’ appraisal of the program, not whether pain, function, or pain modulation changed.

The record describes a single-group study with no like-for-like control group. Consequently, it does not provide a randomized comparison of the program with usual care, another intervention, or no intervention. It also cannot separate changes associated with the program from changes that might occur over time or for other reasons.

The study’s broader rationale concerns pain modulation and movement in knee osteoarthritis. The brief summary describes a future research aim of assessing change in pain severity mediated by change in descending modulation. That is a proposed focus for later research, not the primary endpoint reported for this feasibility study.

The registry record does not report the primary acceptability count or a result for the other outcomes. It therefore does not establish how acceptable participants found the content, or whether pain, function, or pain modulation changed.

3. Trial Design

The registry identifies NCT04954586 as a completed, single-group study sponsored by McMaster University. It lists an enrollment of 19 and a study start date of 2022-05-04, with primary completion on 2022-10-27. The condition is knee osteoarthritis. The study is not described as a randomized comparison: allocation is listed as NA, and the design is identified as single group. Masking is listed as none.

The intervention is named Pain Informed Movement. Its description specifies an eight-week in-person group exercise program held twice weekly. The movement component is described as 60 minutes, and participants were to receive instructions for a third home session, facilitated by exercise handout sheets. The registry description of how pain education was delivered is incomplete; further details are not reported in the registry record.

In a single-group design, the observed experience of participants receiving the intervention can be described, but there is no concurrent control group to provide a direct comparison. This design can be used to examine feasibility questions, such as whether participants rate content as acceptable. It does not by itself establish that an intervention caused any change in a health outcome.

The registry lists phase as NA. It identifies the primary completion date and the overall status as completed, but the record does not report the timing or frequency of outcome assessments beyond the primary endpoint timeframe of 8 weeks. Recruitment methods, eligibility details beyond knee osteoarthritis, participant characteristics, adherence, and retention are not reported in the registry record.

The stated aim is to inform a pilot and feasibility randomized controlled trial before a multisite trial. The registry record does not report a randomized phase within this study, a comparator intervention, or a protocol for a later trial. The results described in the record should therefore be interpreted as relating to the feasibility study rather than as a comparative test of effectiveness.

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

Reasons for not completing this period:

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as Acceptability of Content, measured over 8 weeks.

The primary endpoint is Acceptability of Content, measured as a count of participants. Participants rated how useful they found the treatment using a Likert scale from 1 to 5; higher scores indicate a better outcome. The registry defines the endpoint as the count of participants reporting acceptability greater than 4/5, and states that this threshold is considered when deciding whether to proceed without a protocol amendment.

This endpoint addresses participants’ response to the content, which is relevant to deciding whether an intervention is acceptable enough to inform further feasibility work. It is not a direct measure of pain severity, physical function, pain modulation, or treatment effectiveness. A count above the stated threshold would describe how many participants met the acceptability criterion, but would not by itself show why they rated the content as they did or whether the program changed health outcomes.

The registry lists the timeframe as 8 weeks. It does not report the observed count meeting the threshold, the individual ratings, or how missing ratings were handled. Without those results, the acceptability outcome cannot be quantified from the registry record. The endpoint definition is available, but its result is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design allow?

In a single-group study, participants receive the intervention and outcomes can be described for that group. For a feasibility study, this can help characterize the experience of taking part and whether a program’s content is acceptable. However, there is no concurrent group receiving a different condition against which to compare outcomes. In general, without that comparison, changes over time cannot be distinguished from changes due to other influences, such as natural variation, expectations, or events outside the study.

The registry identifies this study as single group, with allocation listed as NA and masking as none. These features mean the record does not describe randomized assignment or masked assessment. The registry does not report further details about outcome assessment procedures. The absence of a control group is especially important when interpreting any apparent change in pain or function: a before-and-after difference, if reported, would not alone establish that the program caused it.

What does the primary endpoint measure?

The endpoint is a count of participants whose rating of content acceptability is greater than 4/5 on a Likert scale from 1 to 5. A count is a frequency, rather than an average rating or a difference between groups. It can communicate how many participants met the stated criterion, but interpretation also depends on knowing the number who completed the rating. The registry record does not report the observed count or its denominator.

In general, dichotomizing a rating at a threshold turns ratings on either side of the cutoff into different categories. This can make a decision rule easier to communicate, but it also discards information about the precise rating and about how far a rating lies from the cutoff. A count meeting the criterion would answer the specific acceptability question defined by the registry; it would not summarize every aspect of participants’ views.

How should estimates and uncertainty be read?

For quantitative outcomes, an estimate describes the observed result according to a specified method. A confidence interval communicates uncertainty around that estimate. In general, uncertainty reflects both the amount of information in the data and variation in the measurements. A point estimate without an interval can give an incomplete account of precision. Neither an estimate nor its interval resolves design limitations: a precise estimate from a single group still does not provide a randomized comparison.

The registry record does not report an estimate, confidence interval, hypothesis test, or p-value for the primary endpoint. It lists zero analyses. No inferential result should therefore be inferred from the endpoint definition or enrollment information. The absence of a reported statistical test is not evidence that a test found no effect.

What is over-dispersion, in general?

Over-dispersion arises when the variation in count data is greater than a statistical model assumes. If a model assumes less variation than the data contain, standard errors can be too small and confidence intervals too narrow. Appropriate count-data methods may account for this extra variation. This is a general issue for count outcomes; the registry record does not report a model or analysis for the acceptability count, so it is not possible to say whether over-dispersion was assessed or relevant to the analysis used.

What do the planning illustrations represent?

Planning calculations are not observed study results. The record’s stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is framed as a stated fraction of the observed effect. For time-to-event calculations, the stated output is a total number of events; for other calculations, it is participants per arm for 80% power or another stated planning target.

These assumptions describe a planning illustration, not the design of this single-group study. The study itself has no two-arm allocation in the registry record. The registry record does not report an observed effect estimate for the primary endpoint, so the planning illustration should not be read as a result or as evidence of the study’s power. Sample-size calculations for a future study are planning tools, not observed power.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Pain Informed Movement")
n      <- c(14)
events <- c(13)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Pain Informed Movement  14  13  92.9  66.1  99.8  68.5  98.7  68.1  98.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary acceptability endpoint and several secondary outcomes: pain modulation, pain intensity over the past 24 hours, function, brain-derived neurotrophic factor, pain catastrophizing, chronic pain self-efficacy, physical performance tests, and anxiety and depression. It also lists 24 outcome measures overall. Having multiple outcomes raises a general multiplicity issue: when many statistical tests are conducted, the chance of at least one apparently unusual result can increase. Study plans may address this through prespecified priorities or adjustment methods, but no multiplicity approach is reported in the registry record.

The record lists zero analyses and does not report an analysis plan, statistical tests, estimates, confidence intervals, or p-values. It is therefore not possible to determine which outcomes were analyzed, how the analyses were conducted, or whether any multiplicity strategy was used. The listed outcomes should not be treated as evidence of positive or negative findings.

Missing-data handling is not reported in the registry record. In particular, the record does not say how incomplete acceptability ratings or other missing outcome measurements were handled, whether participants were included according to a defined analysis population, or whether any imputation method was used. The enrollment figure does not establish the number contributing to each outcome.

Analysis populations are also not reported in the registry record. The record does not specify whether analyses were intended to include all enrolled participants, participants who attended a defined amount of the program, or another group. Interim analyses and stopping rules are not reported in the registry record. Without these details, the analysis process and the potential influence of missing data or repeated testing cannot be evaluated.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry reports zero serious adverse events and zero other adverse events for the Pain Informed Movement group, with 19 at risk in each reported category. It also reports zero deaths. These figures describe the adverse-event counts entered in the registry record; they are not a demonstration that the intervention was free from risk.

Event counts should be interpreted in the context of how events were defined, elicited, monitored, and reported. Those details, along with the observation period for adverse events, are not reported in the registry record. The record also does not explain whether events were counted as events or as participants experiencing events, so the figures should not be given a more specific interpretation than the registry supports.

Zero recorded events does not rule out events that were not captured or entered into the record. Nor does it establish that the study could detect uncommon events. The single-group design also provides no comparator for assessing whether event rates differed under another condition. The posted figures are therefore a limited description of reported safety data, not a comparative safety analysis.

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

The record describes a completed feasibility study of Pain Informed Movement for people with knee osteoarthritis. It provides information about the intervention’s broad structure, the study’s single-group design, and the definition of its primary acceptability endpoint. These details clarify what the study set out to assess and what kind of result the primary endpoint was intended to capture.

The endpoint focuses on participants’ ratings of how useful they found the treatment content. It is a feasibility-oriented outcome, not a direct measure of pain relief, improved function, or a change in pain modulation. The study rationale and planned future research concern those clinical outcomes, but the registry record does not report results for them.

The primary acceptability count is not reported in the registry record. Accordingly, the record does not establish whether participants met the acceptability criterion or whether the program would proceed without amendment under the stated rule. It also does not provide reported outcome estimates or measures of precision that would allow the size or uncertainty of any changes to be assessed.

The single-group design cannot provide a randomized treatment comparison. Even if changes in clinical outcomes were available, this design alone would not show that the program caused them. The brief summary identifies a later randomized controlled trial and a subsequent multisite trial as intended future steps for assessing effectiveness; those plans are not results from this study.

The adverse-event entries report zero serious events, zero other events, and zero deaths, but the record does not include details needed to interpret event ascertainment fully. These figures should not be read as proof of no risk. The study’s contribution, as documented, is its feasibility question and outcome framework. The registry record does not contain enough outcome information to judge observed acceptability or clinical effectiveness.

14. Why This Trial Matters Statistically

Feasibility studies address questions that precede a definitive evaluation of effectiveness. Whether participants find intervention content acceptable can inform refinement and the design of later research. In this study, the registry specifies an acceptability threshold and states that the count meeting it is considered when deciding whether to proceed without a protocol amendment. That makes the endpoint relevant to the stated development pathway, even though it is not itself a clinical efficacy measure.

Statistically, clear separation between feasibility outcomes and clinical outcomes matters. A favorable acceptability count, if reported, would describe responses to content; it would not establish a change in pain, function, or pain modulation. Conversely, a clinical outcome measure listed in a registry does not show that an outcome was analyzed or changed. Keeping these questions distinct helps prevent a feasibility result from being interpreted as an effectiveness result.

The single-group design also illustrates why design and analysis must be read together. Descriptive results can characterize the experience of participants who took part, but a comparator is needed for a direct estimate of differences between intervention conditions. The registry’s stated aim of informing later randomized and multisite research is consistent with the distinction between early feasibility work and comparative evaluation.

At the same time, interpretation depends on complete reporting. The primary outcome count, outcome-specific denominators, missing-data methods, and statistical analyses are not reported in the registry record. Without those results, the defined feasibility question cannot be answered from the posted record. The study’s statistical importance is therefore in the question and framework it establishes, while the record leaves the empirical acceptability finding unavailable.

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 most immediate limitation for interpreting this registry record is that it defines the primary endpoint but does not report its observed result. The number meeting the acceptability criterion, the denominator for that outcome, and any uncertainty around the count are not reported in the registry record. This prevents assessment of the endpoint that the record identifies as central to the decision about proceeding without protocol amendment.

The single-group design has no concurrent control condition, and allocation is listed as NA. As a result, the study cannot provide a like-for-like comparison of outcomes under the intervention and another condition. Masking is listed as none; further details about outcome assessment are not reported in the registry record. These design features limit conclusions about causation and comparative effects.

The intervention description is incomplete regarding delivery of pain education. The record describes the movement sessions and home-session instructions, but does not provide the remainder of the education-delivery description. The registry also does not report participant characteristics, recruitment details, attendance, adherence, retention, or outcome-specific completion.

Analysis methods, missing-data procedures, analysis populations, and multiplicity handling are not reported in the registry record. The record lists multiple outcomes but does not provide their results. The adverse-event entries are available, but definitions, monitoring procedures, and the observation period are not reported. Together, these omissions constrain interpretation of feasibility, outcome changes, and safety beyond the recorded counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Feasibility of Pain Informed Movement for Knee OA — NCT04954586.
• Registry record last updated 2024-10-03; status last verified 2024-07.
• Results first posted 2024-10-03.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT04954586 is a completed, single-group feasibility study sponsored by McMaster University, with an enrollment of 19. The condition is knee osteoarthritis, and the intervention is Pain Informed Movement. The program is described as an eight-week in-person group exercise program with twice-weekly sessions and instructions for a third home session. Masking is listed as none, and allocation as NA.

The primary endpoint is the count of participants rating content acceptability greater than 4/5 on a Likert scale from 1 to 5, assessed at 8 weeks. The registry record does not report that count or results for the listed secondary outcomes. It lists zero serious adverse events, zero other adverse events, and zero deaths in the intervention group.

The stated purpose is to inform a pilot and feasibility randomized controlled trial before a multisite effectiveness trial. The record does not report an analysis plan, missing-data methods, or comparative efficacy results.