Post-stroke Fatigue, Inflammation, tDCS: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Post-stroke Fatigue, Inflammation, tDCS (NCT05330988), a randomized na study. The primary outcome is Change in Fatigue Severity Scale (FSS) Score.

2. Clinical Question

The study also describes interest in possible anti-inflammatory effects and lists change in Fatigue Assessment Scale score as a secondary outcome. The specific inflammation measure and a result for the secondary outcome are not reported in the registry record. Thus, the posted primary outcome information concerns fatigue scores, not an established biological mechanism or a broader clinical benefit.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group study. Participants were assigned to real anodal stimulation or sham stimulation. The record lists enrollment as 12, with 6 participants in each arm for the primary outcome summaries. The meaning of single masking—such as which participants or study staff were masked—is not reported in the registry record.

The active group received anodal transcranial direct current stimulation to the top of the head for 20 min. Current was slowly ramped up over 30 secs. The sham procedure also lasted 20 min.; the device was turned on and current was increased and subsequently decreased to zero over 30 secs. These descriptions distinguish the assigned procedures, but the registry does not report information about treatment adherence or whether participants could identify their assignment.

The primary outcome timeframe is baseline and post-intervention (2-weeks). The study is listed as completed. Its recorded start date is 2022-07-12, and primary completion is recorded as 2023-10-31. The phase is listed as NA. A protocol rationale for the enrollment target, the method used to generate the random sequence, allocation concealment, and the details of masking are not reported in the registry record.

The parallel design makes the active and sham groups the relevant comparison. However, the posted outcome information gives each arm's mean change and standard deviation without an estimable between-group result. Randomization is a design feature intended to support a fair comparison; it does not by itself establish that a treatment difference is precisely estimated or that all potential sources of bias were controlled.

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

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 Fatigue Severity Scale (FSS) Score, measured over Baseline, post-intervention (2-weeks).

The primary endpoint is change in Fatigue Severity Scale (FSS) score. The FSS is described as a patient-reported measure of trait fatigue over the past 7 days. Its range is 7 to 63, and higher scores indicate greater fatigue. The registry identifies the measure at baseline and post-intervention (2-weeks).

A patient-reported fatigue score can capture the participant's experience rather than relying only on an observer's impression. Repeating the measure allows the study to describe how scores changed during the intervention period. The endpoint is continuous: each participant's score can take values across the scale, and the registry reports group means with standard deviations.

Change scores need careful interpretation. A negative group mean and a positive group mean have opposite numerical directions, but the record does not explicitly state the subtraction convention used to calculate change. The scale's direction is clear—higher FSS scores indicate greater fatigue—but the precise interpretation of change direction depends on how the change was defined. The record does not provide individual measurements, confidence intervals, or a directly estimated active-versus-sham effect. Accordingly, the arm summaries describe the posted endpoint but do not establish the size or precision of a comparative effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is a continuous measure, and the registry reports a mean and standard deviation for each arm. These statistics answer different questions. The mean describes the center of the recorded changes in an arm. The standard deviation describes how spread out individual changes are around that arm's mean. Neither statistic alone gives the uncertainty in an active-versus-sham comparison.

What would a between-group estimate represent?

A comparative analysis would estimate how much the mean change in one assigned group differs from the mean change in the other, according to the analysis specified for the study. Its uncertainty would ordinarily be expressed with a confidence interval or a test result. A confidence interval is a range of values compatible with the data and the assumptions of the analysis; it helps readers judge whether the estimate is precise or remains compatible with a wide range of effects. This is general statistical explanation, not a result reported for this trial.

For this endpoint, the registry reports no estimable two-arm comparison. No comparative estimate, confidence interval, or p-value is reported in the registry record. It would therefore be inappropriate to treat a difference inferred by visually comparing the arm means as though it were the trial's analyzed effect. No new contrast is calculated in this interpretation.

How should the standard deviations be read?

The standard deviation is a descriptive measure of participant-to-participant variability in the observed changes. It does not indicate how many participants improved, and it is not a range containing all participant values. It also is not the same as a confidence interval around the mean. In small groups, a standard deviation estimated from observed participants can itself be uncertain. The record gives the group standard deviations but does not report further analysis of their uncertainty.

Differences in dispersion can matter when comparing groups. General statistical methods may account for unequal variability or use assumptions about a common variance, depending on the chosen procedure. Over-dispersion—greater variability than an analysis model anticipates—can make standard errors too small if the model does not accommodate it, yielding confidence intervals that are too narrow and tests that are too optimistic. The registry record does not identify a comparison method or say how unequal dispersion was addressed, so no conclusion can be drawn about which approach, if any, was used.

What can the planning assumptions establish?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It is explicitly distinct from the study's own design. The record does not report a sample-size justification from the trial protocol. A planning illustration is conditional on its assumptions and is not observed power, a probability that the treatment effect is real, or a substitute for an uncertainty interval around the observed result. No planning figure is interpreted as an observed trial result.

More generally, a sample-size calculation asks how many participants per arm might be needed under specified assumptions to detect a target effect with a chosen operating characteristic. Its output depends on the target effect and variability assumptions. If those assumptions are based on observed results from a small study, they may not represent effects or variability in a later study. The registry's description does not supply the trial's own design rationale, and it does not establish that a particular target effect was prespecified.

What analyses are documented?

The registry lists no analyses for the posted outcomes and marks the two-arm continuous comparison as missing or not estimable. It does not report whether the primary analysis was intended to compare post-intervention scores, changes from baseline, or an adjusted model. It also does not state whether any covariates, transformations, or alternative models were used. These omissions matter because different analytic choices can produce different estimates and uncertainty, especially when the groups are small or the outcome distribution does not fit model assumptions.

The trial is described as randomized and parallel, but those design labels are not a complete statistical analysis plan. The allocation method, planned handling of missing outcomes, choice of comparison test, confidence level for intervals, and approach to protocol deviations are not reported in the registry record. Without those details, the safest reading is limited to the reported arm-specific summaries and the registry's explicit indication that a two-arm comparison was not estimable.

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("Real", "Sham")
n   <- c(6, 6)
m   <- c(-0.4, 0.2)
sp  <- c(0.9, 0.4)
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  Real  6  -0.400  0.900  -1.344  0.544
CARM  Sham  6  0.200  0.400  -0.220  0.620

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies change in FSS score as the primary outcome and change in Fatigue Assessment Scale (FAS) score as a secondary outcome. It lists two outcome measures, but the specific result reported for interpretation is the FSS arm summary. A result for FAS is not reported in the registry record. The study summary also describes interest in inflammation, but a specific inflammation outcome and its result are not reported in the registry record.

When a study examines multiple outcomes or multiple analyses, the chance of finding an apparently notable result can increase if the analyses are treated as independent opportunities for discovery. Statistical approaches can control or describe this multiplicity, but the record does not report a multiplicity adjustment or a plan for prioritizing outcomes beyond identifying FSS as primary and FAS as secondary. It would be inappropriate to infer that an adjustment was or was not performed outside the posted record.

The registry does not report how missing outcome data were handled, whether any participants lacked post-intervention scores, or what imputation or sensitivity methods were used. It also does not identify the analysis population—for example, whether results were intended to include all randomized participants or only those with observed endpoint data. The arm summaries include 6 participants per arm, but that fact alone does not establish the rule used to select observations for analysis.

These omissions limit interpretation of the summaries. Missingness can affect a result when the availability of measurements is related to participants' outcomes or group assignment. Without participant-flow and missing-data details, readers cannot assess that possibility from the registry record.

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 in the real-stimulation arm and zero in the sham arm. It also reports zero other adverse events and zero deaths in each arm. Each arm's at-risk count is 6 for the serious and other adverse-event summaries.

These figures describe events recorded in this study; they do not establish that the interventions carry no risk. The enrollment and observation represented by this trial are limited, and a zero count cannot rule out uncommon events or events not captured in the registry. The record does not provide detailed event definitions, ascertainment procedures, follow-up duration for safety, or information about whether any events were considered related to the assigned procedure.

No serious adverse-event terms are listed. The lack of listed terms is consistent with the reported zero serious adverse events, but it should not be read as a comprehensive assessment of safety beyond what the registry records. These counts are descriptive and do not provide a comparative estimate of risk or a formal safety analysis.

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

The registry records a completed randomized comparison of anodal stimulation with sham stimulation, with FSS change as the primary endpoint. The posted results give mean change and standard deviation by arm. The real arm's mean is -0.4 with a standard deviation of 0.9; the sham arm's mean is 0.2 with a standard deviation of 0.4. The record does not provide an estimable between-group comparison.

That distinction is central. Within-arm summaries describe what was observed among participants in each group, while a treatment comparison asks whether the outcomes differ between assigned groups and quantifies uncertainty in that contrast. The registry does not provide the estimate or uncertainty needed to answer the comparative question. Nor does it report the change-score subtraction convention, which affects how the signs of the means should be interpreted against the scale's direction.

The result therefore does not establish that active stimulation changed fatigue more or less than sham stimulation. It also does not establish that the interventions were equivalent. Absence of an estimable comparison is not evidence that the effect is exactly zero; it means the registry record does not provide a usable comparative estimate for this endpoint.

The study's stated interest includes possible anti-inflammatory effects, but a specific inflammation endpoint and result are not reported in the registry record. The record lists FAS change as a secondary outcome, without a result in the information. The primary FSS summaries should not be extended to those other questions.

The adverse-event counts are zero for serious events, other events, and deaths in both arms. Those counts are reassuring only as a description of what was recorded in this small study; they cannot rule out events that might occur in a larger or longer study. Overall, the record offers limited descriptive information, but not the comparative precision or outcome coverage needed for broader conclusions.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the difference between reporting arm summaries and reporting a treatment comparison. Means and standard deviations are useful descriptive quantities, but they do not answer the randomized comparison by themselves. A reader needs the contrast and its uncertainty to judge how compatible the data are with different possible effects.

The registry explicitly marks the continuous two-arm comparison as missing or not estimable. That transparency is important: it prevents the arm summaries from being mistaken for a complete inferential result. It also highlights how much interpretation depends on details beyond the outcome numbers, including the definition of change, the analysis population, and the method used to handle missing observations.

The enrollment of 12 and the reported 6 participants in each arm make clear that the posted summaries arise from a small study. In small studies, estimates can be imprecise and sensitive to the values of individual participants. This is a general statistical concern, not a claim about any unreported participant-level pattern in this trial. The registry does not give a confidence interval that would show the precision of the primary comparison.

The trial also illustrates why study aims and registered outcomes should be distinguished. The summary mentions inflammation, while the specific primary endpoint is FSS change and the listed secondary outcome is FAS change. The record does not report a specific inflammation measure or its result. Separating these questions avoids treating a stated research interest as though it were a documented finding.

Finally, a planning illustration based on observed data is not the same as a prespecified design justification, and neither is the same as observed power. The registry's distinction between planning assumptions and trial results is essential to interpreting evidence responsibly. Here, the main statistical lesson is the need for a clear, estimable comparative analysis and transparent reporting of its uncertainty.

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 the result is that no estimable comparison between real and sham stimulation is reported. The arm-specific means and standard deviations do not include an uncertainty interval for the contrast. Without that result, the registry does not support a precise statement about the relative change in FSS scores.

The record does not specify the change-score subtraction convention. Although it states that higher FSS scores indicate greater fatigue, the direction of change cannot be fully interpreted from the signs alone without knowing how change was calculated. It also does not report individual scores, baseline group summaries, or post-intervention group summaries, so the reader cannot examine those components separately.

Details needed to evaluate the analysis are not reported in the registry record. These include the statistical test or model, the analysis population, the approach to missing observations, any baseline adjustment, and any sensitivity analyses. The record also does not describe allocation concealment or identify who was masked. These are reporting limitations; they do not establish that a particular procedure was absent.

The study's small enrollment limits the amount of information in the posted summaries and the ability to assess variability reliably. The zero adverse-event counts similarly cannot rule out uncommon events. The FAS secondary result and a specific inflammation endpoint are not reported, limiting interpretation of the study's broader stated aims.

Finally, the registry gives no protocol-based sample-size rationale or detailed statistical analysis plan. The described planning illustration is not identified as the trial's own design justification. Together, these gaps mean the reported data are best read as descriptive arm summaries rather than a definitive estimate of comparative effect.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Post-stroke Fatigue, Inflammation, tDCS — NCT05330988.
• Registry record last updated 2024-12-10; status last verified 2024-11.
• Results first posted 2024-12-10.
• 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

NCT05330988 is a completed randomized, single-masked, parallel-group study sponsored by Medical University of South Carolina. It compared anodal transcranial direct current stimulation with sham stimulation for post-stroke fatigue. Enrollment is listed as 12, with 6 participants in each arm for the primary outcome summaries. The recorded start date is 2022-07-12, and primary completion is 2023-10-31.

The primary outcome was change in Fatigue Severity Scale score from baseline to post-intervention (2-weeks). The registry reports mean change and standard deviation by arm, but marks a two-arm comparison as missing or not estimable. Change in Fatigue Assessment Scale score is listed as secondary; its result and a specific inflammation outcome are not reported in the registry record.

Zero serious adverse events, other adverse events, and deaths are recorded in each arm. The record does not provide a comparative safety analysis or the statistical details needed to interpret the primary outcome beyond its descriptive summaries.