Mindfulness After Stroke: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mindfulness After Stroke (NCT04553679), a registered phase not stated study. The primary outcome is Change in Stroke Impact Scale.

2. Clinical Question

The study addressed both the online program’s usability and participants’ experiences, as well as changes in health-related measures. The registry description says quality of life, depression, anxiety, stress and sleep quality were to be assessed before and after the intervention and at 1 month after it. Feedback about usability and satisfaction was to be gathered after the intervention, with changes made in response to participant feedback.

This is not a question about whether the intervention outperformed an untreated or alternative-treatment group. The record describes a development and assessment study, with stroke survivors and caregivers in role-based groups. Because it does not report random allocation or a control comparison, changes over time cannot by themselves separate an intervention effect from other explanations for change. The registry record also does not report numerical results for the primary outcome, so the magnitude and precision of any change cannot be assessed.

3. Trial Design

The registry record describes a completed study titled “Mindfulness After Stroke,” with the official title “Development of an Online Mindfulness Program for Stroke Survivors and Their Caregivers.” The sponsor was the University of Southern California. The recorded study start was 2020-10-01, and the primary completion date was 2021-07-01. The enrollment was 16.

The behavioral intervention was an online mindfulness program. The two participant groups were stroke survivors and caregivers. The record defines stroke survivors as participants who have had a stroke, and caregivers as participants caring for someone who has had a stroke. These are participant-role groups; the registry record does not describe them as randomized treatment arms or as a treatment-versus-control comparison. Allocation is not stated.

The primary outcome was change in Stroke Impact Scale score from baseline to 3 weeks. The scale is described as a 59-item measure divided into 8 domains, with scores from 0-100; higher scores indicate better quality of life and lower stroke impact. It was not administered to caregivers. Two stroke survivors did not complete the post-intervention measurement.

The registry description also identifies intended assessments of quality of life, depression, anxiety, stress and sleep quality before and after the intervention and at 1 month after it. Named secondary outcomes include changes in Hospital Anxiety and Depression Scale, National Institute of Health Perceived Stress Survey, Single-Item Sleep Quality Scale, World Health Organization Quality of Life-bref and Zarit Burden Interview scores, as well as an adapted usability questionnaire.

The registry record does not report a detailed protocol, a sample-size justification, a statistical analysis plan, or an explanation of how participants entered the study. It reports no analyses. Consequently, the record supports a description of the intended study and recorded outcome measures, but not a detailed account of how the analysis was conducted.

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:

Analysis population for the primary outcome, as defined in the registry: The Stroke Impact Scale is a measure of stroke severity. It was not administered to caregivers. Two stroke survivors did not complete the post-intervention measurement.

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 Change in Stroke Impact Scale, measured over from baseline to 3 weeks.

The primary endpoint was change in Stroke Impact Scale score from baseline to 3 weeks. The measure is described as assessing quality of life and the impact of stroke after the intervention. It contains 59 items divided into 8 domains, with scores ranging from 0-100. Higher scores represent better quality of life and lower stroke impact.

The scale is specific to stroke-related functioning and impact, so it was not administered to caregivers. The registry record states that two stroke survivors did not complete the post-intervention measurement. It does not report the endpoint’s numerical results, such as the mean change, standard deviation, confidence interval or a statistical test. The number of stroke survivors included in an analysis of this endpoint is not reported in the registry record.

In general, a change score describes how a measure differs between a starting assessment and a later assessment. Its interpretation depends on the scale, the timing of measurement, the amount of variation among participants and the completeness of follow-up. A group average can describe the direction and typical size of change, but does not show whether every participant changed in a similar way. Without the numerical endpoint results and an uncertainty estimate, the extent and precision of change cannot be evaluated from the registry record.

The outcome’s stated measurement window is baseline to 3 weeks. The record does not establish that this window represents the full duration of the intervention, and it does not report a threshold for interpreting a change as important to participants. Such details are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. It reports no analyses. The numerical outcome estimates and inferential results are not reported in the registry record, so there is no trial-specific statistical estimate to interpret. The explanations below describe general statistical concepts, not methods confirmed as having been used in this study.

What does a mean change describe?

In general, a mean change is the average of the individual changes between an initial measurement and a later measurement. For the stated primary endpoint, the relevant comparison is baseline to 3 weeks on the Stroke Impact Scale. A positive or negative direction should be interpreted using the scale’s scoring convention: higher scores represent better quality of life and lower stroke impact. The registry record does not report the mean change, so its direction and magnitude cannot be stated.

A mean is a group-level summary. It does not imply that all participants had the same change, or even that all changes had the same direction. The standard deviation gives a description of the spread of participant values around the mean. It is not the same as the uncertainty around the estimated mean. Neither the mean nor the standard deviation for the primary outcome is reported in the registry record.

How would uncertainty be assessed?

In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical method. A narrower interval indicates greater precision, while a wider interval indicates less precision. A confidence interval for an average change would help distinguish an estimate that is relatively precise from one with substantial uncertainty. No confidence interval for the Stroke Impact Scale outcome is reported in the registry record.

A p-value, when reported, describes how compatible the observed data are with a specified statistical null hypothesis under the analysis assumptions. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. The registry record reports 0 analyses and does not provide a p-value for the primary outcome.

Why does the study structure matter?

In general, random allocation can help make comparison groups similar in expectation, while a suitable control group can help account for changes that might occur without the intervention. The registry record does not describe random allocation and notes that the arms are not a like-for-like control comparison. The stroke survivor and caregiver groups are defined by their roles, and the Stroke Impact Scale was not administered to caregivers. Their results therefore should not be treated as two comparable treatment groups.

A change observed between baseline and follow-up is a within-group description. Without an appropriate comparison, changes could reflect the intervention, other experiences during follow-up, measurement variation, or changes in who completed follow-up. This is a general limitation of interpreting before-and-after findings, not a claim about which explanation applies in this study.

What do the planning assumptions mean?

The registry record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. These are assumptions for planning, not evidence of observed power. A planning calculation estimates a sample size under its chosen assumptions; it does not show the probability that the completed study detected an effect. No numerical planning results or observed-effect estimate are reported in the registry record, so the illustration’s output cannot be assessed from the record.

In general, a two-sided significance level allows departures in either direction to count as evidence against a null hypothesis. Equal allocation is an assumption about how participants would be assigned between comparison groups. A normal approximation uses a mathematical approximation to estimate the sampling distribution. The suitability of these assumptions depends on the design, outcome and analysis. The registry record does not report a full statistical plan that would establish how such planning assumptions relate to the actual study.

The planning description refers to two arms, but the recorded groups are stroke survivors and caregivers, and the registry record explicitly warns that they are not a like-for-like control comparison. This means the planning assumptions should not be read as confirmation that the study conducted a balanced randomized comparison. Allocation is not stated.

How should incomplete measurements be considered?

In general, missing outcome measurements can affect both the number of observations available for analysis and the interpretation of an estimate. If participants with missing follow-up measurements differ systematically from those with complete measurements, an average among completers may not represent the originally enrolled group. Methods for handling missing data rely on assumptions; their appropriateness depends on why values are missing and what information is available. The registry record notes two missing post-intervention Stroke Impact Scale measurements among stroke survivors, but does not report a method for addressing them.

Statistical interpretation would ordinarily consider the estimate, its uncertainty, the measurement scale, the comparison design and the handling of incomplete data together. Here, the registry record does not report numerical primary outcome results, an inferential analysis or a missing-data method. General statistical principles can clarify what those items would mean, but they cannot substitute for trial-specific results.

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("Stroke Survivors")
n   <- c(11)
m   <- c(2.3)
sp  <- c(24.3)
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  Stroke Survivors  11  2.300  24.300  -14.025  18.625

11. Multiplicity, Missing Data and Analysis Populations

The registry record identifies one primary outcome, change in Stroke Impact Scale score, and several additional outcomes covering anxiety and depression, perceived stress, sleep quality, quality of life, usability and caregiver burden. It reports 0 analyses. Numerical results for the primary or secondary outcomes are not reported in the registry record.

In general, testing multiple outcomes or multiple time points increases the chance that at least one result may appear noteworthy by chance. Statistical plans can address this through prespecified outcome hierarchies or adjustments for multiple testing. The registry record does not report whether any such approach was planned or used. It also does not report how the different outcome measures or assessment times were prioritized for analysis.

The description states that quality of life, depression, anxiety, stress and sleep quality were to be assessed before and after the intervention and at 1 month after it. The primary Stroke Impact Scale timeframe is baseline to 3 weeks. The registry record does not report whether all intended measurements were completed or how repeated measurements were analyzed.

Missing data are particularly relevant to the primary outcome because two stroke survivors did not complete the post-intervention measurement. The number with complete baseline and follow-up scores, the analysis population, and any imputation or other missing-data procedure are not reported in the registry record. It is therefore not possible to determine how the incomplete measurements affected the reported analysis; no analysis results are reported.

The record also does not report a statistical analysis plan, interim analyses, a sample-size justification or a prespecified approach to multiplicity. These details are not reported in the registry record and should not be inferred from the outcome list or planning assumptions.

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.

Most frequent non-serious adverse event terms

The registry record lists serious and other adverse-event counts separately for stroke survivors and caregivers. For stroke survivors, 0 serious events were recorded among 13 at risk, and 0 other events among 13 at risk. For caregivers, 0 serious events were recorded among 3 at risk, and 1 other event among 3 at risk. Deaths were recorded as 0 in each group.

These are event counts over the study period as represented in the registry record. They are not estimates of the likelihood of an event in a broader population, and the record does not give additional detail about event timing, duration or relationship to the intervention. The one other event is not classified as serious in the posted figures. No serious-event terms are listed.

In general, zero recorded events in a small study do not demonstrate that an intervention has no risk. Small studies have limited ability to characterize uncommon events, and the registry record does not report a detailed safety analysis. The group counts should be read as the safety information recorded for this study, rather than as a complete assessment of safety or a comparison with another treatment.

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

The registry record describes a study intended to develop an online mindfulness program for stroke survivors and caregivers. Its aims included assessing relevance, satisfaction and ease of use, measuring several health-related outcomes, and using participant feedback to revise the intervention. These are development and assessment objectives, not a stated randomized comparison of treatment against control.

The record identifies change in Stroke Impact Scale score from baseline to 3 weeks as the primary outcome. It explains the scale’s scoring direction and notes that it was not administered to caregivers. However, it does not report numerical outcome results or any analyses. The direction, size and precision of the primary outcome change therefore cannot be determined from the registry record.

The record also does not report numerical results for the named secondary outcomes or usability measure. It cannot establish from those measures whether participants found the program relevant, satisfying or easy to use, or whether the health-related measures changed. The study description says participant feedback would guide changes toward a final version, but the actual feedback and resulting changes are not reported in the registry record.

The lack of a described randomized control comparison is important for interpretation. Even if a before-and-after change were reported, that change alone would not show that the intervention caused it. A control comparison and a clear analysis plan would be needed to support a stronger causal interpretation. The record does not report such a comparison or plan.

The safety counts record no serious adverse events and no deaths in either group, alongside one other adverse event among caregivers. These data describe recorded events in this study, but do not establish that the intervention is free of risk. Overall, the registry record documents the study’s intent, outcome definitions and some safety counts, but not the efficacy, usability or acceptability results needed to draw conclusions about observed outcomes.

14. Why This Trial Matters Statistically

This study is statistically important as an example of a development question that is broader than estimating a treatment effect. The stated aims include relevance, satisfaction and ease of use, alongside health-related measures. In early program development, participant feedback can inform how an intervention is refined, while outcome measures can describe changes that merit further evaluation. These aims should be distinguished from demonstrating comparative effectiveness.

The role-based groups also matter. Stroke survivors and caregivers have different roles, and the primary Stroke Impact Scale was not administered to caregivers. Treating them as if they formed intervention and control groups would obscure that design distinction. The registry record explicitly cautions that the arms are not a like-for-like control comparison and does not state allocation.

The outcome schedule and incomplete follow-up illustrate why analysis populations and missing-data methods matter. Two stroke survivors did not complete the post-intervention primary measurement. Without a reported analysis population or method for handling those missing measurements, readers cannot assess how follow-up affected the estimate. The absence of posted numerical analyses further limits statistical interpretation.

The record’s planning assumptions are also useful to interpret cautiously. General sample-size calculations depend on stated assumptions about the comparison, effect to detect and analysis. They are planning tools, not observed power and not a substitute for reported estimates and uncertainty. Here, the record does not report numerical planning outputs or the observed effect on which the illustration was based.

For readers assessing clinical studies, the distinction between a registry description and posted results is consequential. A clearly defined endpoint and study aim do not themselves establish what happened to participants. Transparent outcome estimates, uncertainty, missing-data handling and analysis methods are needed to judge the evidence. Those results and details are not reported in this registry record.

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 registry record does not report numerical results for the primary Stroke Impact Scale outcome or the named secondary outcomes. It reports 0 analyses. Consequently, the magnitude and precision of change, and any statistical evidence associated with the outcomes, cannot be evaluated from the record.

The study does not have a described like-for-like control comparison. The registry record states that allocation is not stated and cautions that the arms are not a like-for-like control comparison. Stroke survivors and caregivers are distinct participant groups, and the primary stroke impact measure was not administered to caregivers. This limits interpretation of any between-group comparison as an estimate of an intervention effect.

Two stroke survivors did not complete the post-intervention Stroke Impact Scale measurement. The record does not report the number included in an endpoint analysis or a method for handling missing measurements. It also does not report whether other outcome measures were incomplete or how the repeated assessments were analyzed.

The registry record does not describe a statistical analysis plan, a sample-size justification, interim analyses or a prespecified strategy for multiple outcomes. While it states planning assumptions for an illustration, numerical outputs and the observed-effect estimate are not reported. The record does not explain how those assumptions correspond to the actual participant groups.

Finally, the stated usability and satisfaction aims are not accompanied by numerical results or the participant feedback that informed changes to the intervention. The safety record includes a small number of participants and provides counts, but not detailed event descriptions or a comparative safety analysis. These omissions limit conclusions about feasibility, usability, outcome change and safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Mindfulness After Stroke — NCT04553679.
• Registry record last updated 2023-02-22; status last verified 2022-05.
• Results first posted 2023-02-22.
• 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

The registry record describes a completed study of an online behavioral mindfulness program for stroke survivors and caregivers, sponsored by the University of Southern California. Enrollment was 16. The study aimed to assess relevance, satisfaction and ease of use, measure health-related outcomes, and use participant feedback to guide revisions.

The primary outcome was change in Stroke Impact Scale score from baseline to 3 weeks. It applied to stroke survivors, and two did not complete the post-intervention measurement. The record lists additional outcomes relating to anxiety and depression, stress, sleep, quality of life, usability and caregiver burden. It reports 0 analyses and does not report numerical outcome results or a statistical analysis plan.

The registry record describes no randomized, like-for-like control comparison; allocation is not stated. It records no serious adverse events or deaths in either participant group, and one other adverse event among caregivers. These counts do not provide a comparative assessment of safety.