Adapting Acceptance and Commitment Therapy for Stroke Survivors With Aphasia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Adapting Acceptance and Commitment Therapy for Stroke Survivors With Aphasia (NCT04984239), a na na study. The primary outcome is Mean Scores on the Client Satisfaction Questionnaire - 8.

2. Clinical Question

The primary measure is satisfaction rather than a direct test of whether the intervention improves communication or other health outcomes. Satisfaction can help assess whether participants found the intervention acceptable, but it does not establish comparative efficacy. With a single arm, changes over time also cannot be separated from other explanations using a concurrent control. This trial is described as an early-stage adaptation and evaluation, with preliminary estimates intended to inform subsequent research.

3. Trial Design

The registry describes a completed Stage I successive-cohort trial of Acceptance and Commitment Therapy adapted for stroke survivors with aphasia. The sponsor is the University of Pittsburgh. The record lists a start date of 2021-11-02, primary completion date of 2024-01-22, status of completed, and enrollment of 20. The phase is listed as NA.

The planned work included developing a treatment manual with input from a stakeholder advisory board of caregivers and stroke survivors with aphasia. The description then names an initial cohort of five participants who would receive an early version and provide feedback, followed by revision of the manual and evaluation in a second cohort of 16. The registry enrollment is 20, and the record does not explain how that enrollment relates to the two cohort sizes in the description.

Only one arm is listed: Acceptance and Commitment Therapy adapted for aphasia. Allocation is NA, masking is none, and the model is sequential. There is no concurrent control group, so the design is not a randomized comparison. The registry describes combining ACT with communication supports and compensatory speech-language treatment, but details such as treatment dose and delivery schedule are not reported in the registry record.

The primary outcome is mean score on the Client Satisfaction Questionnaire - 8 after treatment, within one week of completing the treatment phase. The listed secondary measures cover acceptance, distress, quality of life, aphasia outcomes, communication participation, and resilience. The registry’s description states that pre- to post-treatment changes were to be measured. A detailed protocol, statistical analysis plan, and numerical outcome estimates are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: This study utilized a Stakeholder Advisory Board (SAB) of people with aphasia and care partners to provide input on treatment development. Members of the SAB were not study participants, and therefore were not enrolled as participants.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Data from 17 of the 19 completed participants were included in this analysis. This is due to missing data from the remaining 2 participants.

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 Mean Scores on the Client Satisfaction Questionnaire - 8, measured over Post-treatment (within one week of completing the treatment phase).

The primary endpoint is the mean score on the Client Satisfaction Questionnaire - 8 (CSQ-8), assessed after treatment, within one week of completing the treatment phase. The registry describes the CSQ-8 as a brief questionnaire intended to measure patient satisfaction. It has 8 questions, each rated on a 4-point scale, with summed scores ranging from 8 to 32. Higher scores indicate higher satisfaction, and lower scores indicate lower satisfaction.

Satisfaction was chosen as the primary measure because the stated purpose of the pilot included determining whether the adapted intervention was acceptable to participants. A satisfaction measure can capture participants’ views about their experience and can inform whether an intervention is suitable for further study. It is not, by itself, a measure of treatment efficacy, communication improvement, or quality-of-life change.

The registry reports that data from 17 of the 19 completed participants were included in the primary analysis because data were missing for the remaining 2. The numerical mean and standard deviation for the CSQ-8 are not reported in the registry record. The record therefore does not show the observed level of satisfaction or the precision of an estimated mean. It also does not report a comparison against another group or a stated threshold for interpreting the score as acceptable.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods matter because a measured score is an estimate from participants in a particular study, not a complete description of how an intervention might perform in other settings. The registry identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. It does not report the numerical mean or standard deviation, so the endpoint’s observed level and spread cannot be assessed from this record.

What does a mean and standard deviation describe?

In general, a mean is a measure of the center of a set of scores. A standard deviation describes how spread out individual scores are around that center. Together they can help characterize participant responses, but they do not show every response or explain why participants gave those scores. For the CSQ-8, the score combines responses across 8 questions rated on a 4-point scale, with summed scores from 8 to 32. The registry indicates that higher scores mean higher satisfaction. It does not provide the observed mean or standard deviation.

How should uncertainty be understood?

In general, a confidence interval is a range of values compatible with the observed data under the assumptions of a statistical method. A narrow interval indicates greater precision than a wide interval, while neither interval alone resolves possible bias or limitations in the design. No confidence interval for the primary outcome is reported in the registry record. Nor does the record report a p-value or a tested comparison for the primary outcome. Without an estimate and its uncertainty, a reader cannot assess how precise the satisfaction result would be.

What can a single-arm sequential design estimate?

A single-arm design can describe scores and experiences among participants who receive the intervention. Where measurements are made before and after treatment, changes can be described within participants. In general, however, a change from baseline does not by itself show that the intervention caused the change: time, other care, measurement effects, and other influences may also contribute. A concurrent comparison group can help address some of these alternative explanations, but this study has only one arm. Its sequential cohorts were part of an adaptation process, not a randomized control comparison.

The registry’s primary endpoint is satisfaction measured after treatment rather than a pre- to post-treatment change. Its stated secondary measures include psychological and functional outcomes. The registry describes these as mean scores, but their numerical results and any associated estimates of uncertainty are not reported in the registry record. It is therefore not possible to assess the size or precision of changes from the posted record.

What does the planning illustration mean?

In general, sample-size planning asks how many participants a future study might need to detect a specified effect under stated statistical assumptions. The registry’s accompanying planning approach is described as an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated portion of the observed effect. Such calculations are planning illustrations, not observed power and not results from a randomized comparison in this trial. The required numerical planning outputs and the observed effect estimate are not reported in the registry record, so those quantities cannot be interpreted from the record alone.

In general, a planning estimate depends on the effect assumed, the variability of the outcome, the chosen error rate, and the allocation and analysis assumptions. When a future study is intended to compare groups, planning also depends on the design and the outcome definition. The registry does not report a formal sample-size justification for the current study or a detailed protocol for a future efficacy trial. The enrollment of 20 is a recorded study characteristic; it should not be treated as evidence that a particular power target was met.

Why can over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a statistical model assumes. When a model underestimates variability, standard errors can be too small and uncertainty can appear less than it is. This concept is most relevant to certain count or categorical models and is not a reported finding for the CSQ-8 endpoint in this registry. The primary endpoint is described as a continuous score, and the record does not specify a model that would permit an assessment of over-dispersion.

More broadly, model choice should follow the outcome scale, study design, and analysis objective. The registry lists a mean as the primary outcome summary but does not state whether the analysis used an adjusted model, how assumptions were checked, or whether subgroup or cohort-specific analyses were conducted. Those analytic details are not reported in the registry record. Thus the design and endpoint can be described, but the precision, assumptions, and robustness of an estimated effect cannot be evaluated from the posted statistical information.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Acceptance and Commitment Therapy Adapted for Apha")
n   <- c(17)
m   <- c(29.7)
sp  <- c(5.3)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Acceptance and Commitment Therapy Adapted for Apha  17  29.700  5.300  26.975  32.425

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the CSQ-8 mean as the primary outcome and lists secondary measures covering acceptance, distress, quality of life, aphasia outcomes, communication participation, and resilience. When a study examines multiple outcomes, the chance of at least one apparently unusual result can increase if each result is interpreted as a separate test. In general, a statistical plan may specify a primary outcome, distinguish confirmatory from exploratory analyses, or adjust interpretation for multiple testing. A multiplicity plan is not reported in the registry record. Numerical outcome analyses and test results are also not reported.

For the primary outcome, the registry states that data from 17 of the 19 completed participants were included, while 2 had missing data. This is an analysis population description, not a missing-data method. The registry record does not explain the reasons for missingness, report participant characteristics for those with and without outcome data, or say whether missing scores were imputed. It does not report sensitivity analyses that would show how conclusions might change under different assumptions about the missing observations.

In general, analyzing only participants with recorded scores is most straightforward to interpret when missingness does not distort the analyzed group in a consequential way. If missingness is related to satisfaction or the intervention experience, the analyzed mean could differ from the mean among all completed participants. The record does not provide enough information to assess that possibility. It also does not report a broader analysis population definition, adherence-based analyses, or adjustments for cohort sequence. The registry lists zero analyses, so analysis-level entries are not available. These omissions limit assessment of how the endpoint was analyzed and how robust any result may be.

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 participants with serious adverse events among 20 at risk in the single study arm. It also reports zero participants with other adverse events among 20 at risk and zero deaths. No serious adverse event terms are listed. These are counts in the registry record and should be read as descriptive safety reporting for the study population, not as proof that no adverse events could occur.

The record does not provide event-level descriptions, timing, severity details, or an account of how adverse events were monitored. It therefore does not show how the events were defined or whether events outside the reported categories were collected. The absence of listed serious event terms is consistent with the record’s zero serious affected participants, but does not provide additional detail about surveillance.

There is no control group for comparing event counts between interventions. A zero count in this study cannot establish comparative safety or rule out uncommon events. The enrollment is 20, and the figures are limited to this trial’s recorded participants and reporting. The registry does not report a safety analysis beyond the event counts. These data should be interpreted as the reported counts, not as a general estimate of risk for other populations or settings.

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

The registry describes a study designed to adapt an ACT intervention for stroke survivors with aphasia and gather early information about acceptability, feasibility, and outcomes. The primary endpoint is post-treatment satisfaction measured using the CSQ-8. The record reports that the primary analysis included data from 17 of the 19 completed participants, with missing data for the other 2. However, the numerical mean and standard deviation are not reported in the registry record. Therefore, the posted results do not show the observed satisfaction score or how precisely it was estimated.

The study also lists measures related to acceptance, distress, quality of life, aphasia, communication participation, and resilience. The registry does not report numerical results for these outcomes. Its stated intention to measure pre- to post-treatment changes does not itself establish that changes occurred, how large they were, or whether any change was attributable to the intervention.

The single-arm successive-cohort design is appropriate to describe as an early-stage adaptation and evaluation, but it does not provide a randomized comparison with usual care or another intervention. Without a concurrent comparator, outcomes cannot be used to estimate a comparative treatment effect. The successive cohorts also relate to revision of the intervention manual, and the record does not report cohort-specific outcome estimates.

The adverse event record lists zero serious events, zero other events, and zero deaths among the recorded at-risk participants. Those counts describe what the registry reports for this study, not a guarantee of safety or a comparative safety finding.

Accordingly, the registry supports understanding the study’s aims, design, and primary measure, but it does not provide the numerical outcome evidence needed to characterize satisfaction, changes in secondary outcomes, or the precision of estimates. The study is described as preparing for a subsequent Stage II efficacy trial; the registry record does not report results from such a trial.

14. Why This Trial Matters Statistically

This trial is statistically important because it illustrates a distinct role for early-stage research. Before a later efficacy comparison, an intervention may need to be adapted to the communication needs of its intended participants and assessed for acceptability and feasibility. The registry describes stakeholder input, successive cohorts, manual revision, and an adapted therapy that incorporates communication supports and compensatory speech-language treatment. These are design features intended to inform intervention development, rather than components of a randomized efficacy test.

The choice of satisfaction as the primary endpoint matches the stated acceptability aim. It also illustrates why endpoint interpretation depends on the research question: a satisfaction score can characterize participant experience, but it is not interchangeable with an outcome such as communication participation or quality of life. The registry lists several such secondary measures, but their numerical results are not reported in the registry record.

The record also illustrates the importance of reporting estimates and uncertainty, alongside sample counts. Knowing that 17 of the 19 completed participants contributed primary outcome data does not reveal the average score or its precision. Similarly, zero reported adverse events is a descriptive observation, not proof of no risk. In a small, single-arm study, both outcome estimates and safety counts require cautious interpretation.

Finally, the successive-cohort structure underscores that an intervention can change during development. Clear reporting of cohort-specific procedures and results would help readers understand what version participants received and how the adaptation process relates to measured outcomes. Those details and the numerical outcome estimates are not reported in the registry record. The study’s statistical contribution can therefore be understood from its developmental aims and design, but the posted record does not permit assessment of its outcome magnitudes.

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 limitation for interpreting outcomes is that numerical results are not reported in the registry record. For the primary CSQ-8 endpoint, the record identifies the measure and analysis population but not the mean or standard deviation. It likewise does not provide numerical results for the listed secondary measures. This prevents assessment of outcome magnitude and precision.

The study has one arm and no concurrent control group. Its results cannot establish how outcomes compare with another intervention or with no intervention. Because the design is sequential and intended to support adaptation, participants may have received versions of the intervention that differed as the manual was revised. The registry does not report cohort-specific treatment or outcome details.

The primary analysis included data from 17 of 19 completed participants, with missing data for 2. The reasons for missing data and their potential relationship to satisfaction are not reported in the registry record. There is no reported missing-data procedure or sensitivity analysis. The enrollment is 20, but the record does not explain how this relates to the described initial cohort of five and second cohort of 16.

The record does not report participant characteristics beyond the listed conditions, treatment dose, detailed eligibility criteria, outcome assessment procedures beyond the primary timeframe, or a detailed statistical analysis plan. It does not describe how multiplicity was handled or whether results were adjusted for cohort sequence. The serious and other adverse event counts are reported as zero, but event-monitoring procedures and additional safety details are not reported. These limitations constrain interpretation of both the intervention experience and the generalizability of any findings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Adapting Acceptance and Commitment Therapy for Stroke Survivors With Aphasia — NCT04984239.
• Registry record last updated 2025-04-25; status last verified 2025-04.
• Results first posted 2025-04-25.
• 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

NCT04984239 is a completed Stage I successive-cohort study sponsored by the University of Pittsburgh. It enrolled 20 participants and studied Acceptance and Commitment Therapy adapted for stroke survivors with aphasia. The registry lists one behavioral intervention arm, allocation as NA, masking as none, and the phase as NA. The listed study dates are 2021-11-02 for start and 2024-01-22 for primary completion.

The primary outcome was mean CSQ-8 score after treatment, within one week of completing the treatment phase. The registry states that data from 17 of 19 completed participants were included because data were missing from the other 2. Numerical primary and secondary outcome results are not reported in the registry record. The record lists zero serious adverse events, zero other adverse events, and zero deaths. It describes the study as an intervention adaptation and preliminary evaluation in preparation for a subsequent Stage II efficacy trial.