Fostering Eating After Stroke With Transcranial Direct Current Stimulation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Fostering Eating After Stroke With Transcranial Direct Current Stimulation (NCT01919112), a randomized na study. The primary outcome is To Assess Changes in Penetration and Aspiration.

2. Clinical Question

3. Trial Design

The registry describes a randomized, quadruple-masked, parallel-group trial sponsored by Beth Israel Deaconess Medical Center. It lists 42 participants as enrolled and the study status as completed. The phase is recorded as not applicable. The listed conditions are dysphagia and stroke.

Participants were assigned to high-dose anodal tDCS, low-dose anodal tDCS, or sham stimulation. The high-dose schedule was 2 milliamps twice daily for 5 days, while the low-dose schedule was 2 milliamps once daily for 5 days. Each active schedule was paired with swallowing exercises. The sham group was described as receiving twice-daily swallowing exercises only. The registry does not give additional details about the randomization procedure or the masking procedures, so those aspects are not reported in the registry record.

The primary outcome was change in PAS score, measured before stimulation and after 5 days following completion of stimulation. The record says that an average PAS score was computed over 9 swallows. Secondary outcomes included dietary intake, physiological measures of pharyngeal strength, briskness of swallow onset, laryngeal excursion, and PAS change after covariate adjustment. Dietary intake was assessed at study onset and after 1 month; the other listed physiological measures were assessed at baseline and after 5 days following completion of stimulation.

The record describes standardized swallowing and neurological assessments and brain MRI scans during the study. It does not report the allocation ratio, the details of the masking, the target enrollment rationale, or the trial's original sample-size assumptions. Those details 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: A total of 328 subjects were screened for the trial, of which 214 did not fulfill all trial criteria and 72 refused consent. A total of 42 subjects were eventually enrolled: 14 subjects in High-Dose tDCS, 13 in Low-Dose tDCS and 15 in Sham arms.

Primary Analysis-day 5 of Intervention

Secondary Analysis-day 30

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis of participant was based on an intention to treat principle.

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 To Assess Changes in Penetration and Aspiration, measured over Scores will be measured before tDCS and after 5 days after completion of stimulation.

The primary endpoint was change in the Penetration and Aspiration Scale (PAS), reported as a mean with a standard deviation. PAS is an 8 point ordinal scale used to quantify penetration and aspiration events observed during videofluoroscopic swallowing evaluation. Its values range from 1, representing no penetration or aspiration, to 8, representing severe aspiration. The outcome was calculated as an average across 9 swallows for each participant.

Change in PAS is used in this study to capture whether swallowing-related penetration and aspiration changed during the short stimulation period. Since lower PAS values represent better scores, a negative change is directionally consistent with a decrease in the measured score. The posted arm summaries give mean changes of -0.4 for high-dose tDCS, -0.8 for low-dose tDCS, and -0.8 for sham stimulation. Those arm-level changes alone do not establish whether groups differed; the between-group estimates and their uncertainty are needed for that question.

There is a statistical distinction between the scale's ordinal construction and the registry's choice to summarize its averaged score using a mean and standard deviation. A mean can communicate average change, but it does not show how individual participants' scores were distributed across the scale's categories. The record does not report a separate category-based analysis of PAS.

7. Results Posted in the Registry

• High Dose Anodal tDCS: mean -0.40 versus -0.80 on control; difference 0.40 (95% CI -0.63 to 1.43), standardized effect d = 0.28; z-test p = 0.444.
• Low Dose Anodal tDCS: mean -0.80 versus -0.80 on control; difference 0.00 (95% CI -1.15 to 1.15), standardized effect d = 0.00; z-test p = 1.000.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

To Assess and Compare Changes in Dietary Intake in Each of the Three Groups

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • High Dose Anodal tDCS: mean 2.90 versus 2.10 on control; difference 0.80 (95% CI -0.32 to 1.92), standardized effect d = 0.54; z-test p = 0.161.
  • Low Dose Anodal tDCS: mean 2.50 versus 2.10 on control; difference 0.40 (95% CI -0.91 to 1.71), standardized effect d = 0.24; z-test p = 0.550.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between High Dose Anodal tDCS and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Low Dose Anodal tDCS and the control. The interval gives the range of effects that remain compatible with the data.

To Assess Changes in Physiological Measures of Pharyngeal Strength

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • High Dose Anodal tDCS: mean -0.01 versus -0.02 on control; difference 0.01 (95% CI -0.05 to 0.07), standardized effect d = 0.13; z-test p = 0.732.
  • Low Dose Anodal tDCS: mean -0.10 versus -0.02 on control; difference -0.08 (95% CI -0.15 to -0.01), standardized effect d = -0.84; z-test p = 0.032.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between High Dose Anodal tDCS and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Low Dose Anodal tDCS than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

To Assess Changes in Physiological Measures of Briskness of Swallow Onset

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • High Dose Anodal tDCS: mean 5.20 versus 0.83 on control; difference 4.37 (95% CI -11.46 to 20.20), standardized effect d = 0.21; z-test p = 0.588.
  • Low Dose Anodal tDCS: mean -7.30 versus 0.83 on control; difference -8.13 (95% CI -35.95 to 19.69), standardized effect d = -0.25; z-test p = 0.567.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between High Dose Anodal tDCS and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Low Dose Anodal tDCS and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover dietary intake, physiological measures of swallowing, and an adjusted PAS measure. The posted numerical results include comparisons for dietary intake, pharyngeal strength, and briskness of swallow onset. The registry lists additional secondary outcomes concerning laryngeal excursion and covariate-adjusted PAS, but their numerical results are not reported in the registry record.

Across the outcomes with numerical summaries, the pattern is not uniformly in one direction or uniformly precise. Several comparisons have intervals spanning zero. One low-dose comparison for pharyngeal strength has an unadjusted p-value of 0.032 and an interval that does not span zero; the other comparisons do not provide a similarly clear statistical separation. This mixed pattern does not change the primary-outcome interpretation: both primary comparisons remain uncertain, and the secondary measures assess related but distinct aspects of swallowing or dietary intake.

Secondary outcomes can help describe whether patterns extend beyond the primary measure, but they carry less weight when many outcomes and comparisons are examined without a reported multiplicity strategy. A small unadjusted p-value may arise by chance when multiple hypotheses are tested. The registry record does not report a complete plan for controlling this risk, nor does it provide the reported analyses for all listed secondary measures. The results are therefore best viewed as exploratory context rather than as a replacement for the primary comparisons.

The secondary summaries also use different units and, for some measures, different time points. Directly comparing the numerical size of changes across outcomes would not be meaningful without accounting for those scale differences and their measurement properties. The registry does not give a threshold for clinical importance for these secondary endpoints.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• To Assess and Compare Changes in Dietary Intake in Each of the Three Groups
• To Assess Changes in Physiological Measures of Pharyngeal Strength
• To Assess Changes in Physiological Measures of Briskness of Swallow Onset
• To Assess Changes in Physiological Measures of Laryngeal Excursion
• Change in PAS Scores as an Indicator of Dysphagia Recovery After Covariate Adjustment

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is presented as a continuous summary: a mean PAS change and its standard deviation in each group. The registry defines PAS as an 8 point ordinal scale and says that each outcome score averages 9 swallows. Treating an averaged score as a mean supports a straightforward comparison of group averages. It does not, however, describe the full distribution of participants' scores or how often any particular PAS category occurred.

The comparison of interest is the difference between the mean change in an active-stimulation group and the mean change in sham. A mean difference of 0 would indicate identical group averages in the posted summaries. A positive estimate means the active group's mean change is numerically higher than the sham group's; a negative estimate means it is numerically lower. Because lower PAS scores represent better scores, interpreting the direction also requires remembering that the measure is a change score, rather than a final PAS score alone.

For high-dose tDCS versus sham, the unadjusted mean difference is 0.4. For low-dose tDCS versus sham, it is 0.0. The confidence interval expresses uncertainty around an estimated group difference: values within the interval are compatible with the data under the method used to construct it. When an interval includes zero, the data do not clearly distinguish a nonzero difference from no average difference. That does not prove there is no effect or that the groups are equivalent.

The posted p-values are unadjusted. A p-value describes how inconsistent the observed result would be with a specified null model, under the assumptions of the statistical test. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of a difference. These p-values should be read together with the mean differences and intervals, not as stand-alone verdicts. The registry record does not report the full test specification for these primary comparisons.

The displayed recalculations use the arm-level sample sizes, means, and standard deviations to estimate simple unadjusted comparisons. They do not represent a covariate-adjusted model. The registry's primary-outcome description says that analysis was based on an intention-to-treat principle, but details of the sponsor's primary statistical analysis are not reported in the registry record. The discrepancy indicator is false, so there is no noted disagreement between the posted results and these recalculations.

Standard deviations describe variability among participant-level outcome values within a group. They are not the same as standard errors, which describe uncertainty in an estimated mean. When participant outcomes are more variable, group averages tend to be less precisely estimated for a given sample size. This trial's group sizes for the primary outcome were 14 in the high-dose arm, 13 in the low-dose arm, and 15 in the sham arm. Those counts are relevant to the precision of estimates but do not, by themselves, establish whether the study was adequately powered.

Some secondary comparisons include a standardized effect-size measure. In general, a standardized effect expresses the difference relative to a measure of variability, making results measured on different scales easier to compare in magnitude. It does not remove uncertainty, turn an estimate into a clinical judgment, or establish that an observed result is reliable. The record does not describe a prespecified threshold for interpreting these standardized values.

Over-dispersion is a general concern when outcome variability is greater than a statistical model assumes. If a model assumes less variability than is present, standard errors may be too small and intervals too narrow. The primary comparisons are calculated from posted summary statistics rather than a reported model that specifies a dispersion assumption, so a model-based over-dispersion adjustment is not described in the registry record.

The registry identifies an additional PAS outcome after covariate adjustment, but does not provide a corresponding result in the numerical secondary summaries available. Which covariates would be included, how they would be handled, and whether any such analysis was performed are not reported in the registry record. The record also does not report an interim analysis plan, a complete prespecified statistical analysis plan, or the trial's original sample-size justification. These omissions limit assessment of whether all analyses followed a prespecified approach.

11. Confidence Intervals and Precision

Confidence intervals describe the range of group differences compatible with the observed data under the interval's statistical method. They are useful because a point estimate alone can hide how uncertain the estimate is. A narrow interval indicates greater precision, while a wide interval indicates that the data are compatible with a broader range of possible differences.

For both primary comparisons, the reported interval spans zero. The high-dose estimate is 0.4 and the low-dose estimate is 0.0. In each case, the interval includes values on both sides of zero, so the posted data do not precisely establish the direction of a group difference. This is consistent with the unadjusted p-values of 0.444 and 1.0, respectively, but the interval is more informative than a threshold-based reading of the p-value because it also conveys the range of plausible estimates.

The primary outcome groups are small: the posted counts are 14 for high-dose tDCS, 13 for low-dose tDCS, and 15 for sham stimulation. With limited observations, an estimate can remain uncertain even when the group means differ numerically. The standard deviations are 1.2, 1.5, and 1.6, respectively, indicating variation in participant-level change within each group. The registry does not give a clinically important difference threshold for PAS, so the practical importance of values within the reported intervals cannot be assessed from the record alone.

Intervals do not show every uncertainty relevant to interpretation. They do not account for unreported decisions about missing data, analysis choices, or multiple comparisons. The registry does not state the confidence level used for the posted intervals. Consequently, their main contribution is to show that the primary comparisons remain imprecise and compatible with differences in either direction, rather than to establish a definitive treatment effect or its absence.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size illustration is for planning, not a description of the number enrolled or analyzed. For the primary high-dose tDCS versus sham comparison, the figures are participants per arm. The illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It scales the effect to detect as a stated fraction of the observed effect.

For planning at 100% of the observed effect, the illustration gives 199 participants per arm for 80% power and 266 participants per arm for 90% power. At 75% of the observed effect, it gives 353 participants per arm for 80% power and 472 participants per arm for 90% power. At 50% of the observed effect, it gives 794 participants per arm for 80% power and 1,062 participants per arm for 90% power. Smaller effects require more participants under these assumptions.

In plain language, 80% power means that, if the assumed effect and other planning conditions held, a study of that size would have an 80% chance of detecting the effect using the specified testing approach. The 90% column describes the corresponding chance at the larger proposed sample size. These are planning illustrations based on the observed effect, not observed power for the completed trial. The registry record does not report the trial's original sample-size assumptions or justification. The illustration therefore should not be treated as evidence about the original design process.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.400; pooled standard deviation σ = 1.422.
2. n = 2 × (1.96 + 0.842)² × 1.422² / 0.400² = 198.3, rounded up to 199 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.4                      # observed difference in means
sigma <- 1.42152760815284                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1919112)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 199 (80% power), 266 (90% power)
 75% of observed effect: n per arm = 353 (80% power), 472 (90% power)
 50% of observed effect: n per arm = 794 (80% power), 1,062 (90% power)
power.t.test: 199.2 
Simulated power at n = 199 per arm: 0.800 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when multiple outcomes, treatment comparisons, or statistical tests are evaluated. Even if each test is conducted using a conventional significance threshold, testing many hypotheses increases the chance that at least one result appears notable by chance. This is why a prespecified hierarchy, adjustment procedure, or clear exploratory designation can matter when interpreting secondary findings.

The registry lists several secondary outcomes, including dietary intake, pharyngeal strength, briskness of swallow onset, laryngeal excursion, and covariate-adjusted PAS. Numerical secondary results are posted for three measures, while numerical results for the other listed outcomes are not reported in the registry record. The record does not report whether or how multiplicity was addressed, whether the outcomes were ranked in a hierarchy, or which comparisons were prespecified for confirmatory interpretation. The unadjusted secondary p-values should therefore be treated cautiously.

Missing-data handling is also important because the posted participant counts vary by outcome. The primary outcome description states that the analysis followed an intention-to-treat principle. However, the registry does not explain how missing measurements were handled, whether all randomized participants contributed to each analysis, or whether any imputation method was used. The record does not report reasons for missing outcome data by group.

An intention-to-treat principle generally aims to analyze participants according to their randomized assignments, regardless of adherence, but the exact implementation depends on the handling of unavailable measurements and the analysis population. The primary outcome statement alone does not resolve those practical details. In addition, the registry does not report the complete statistical analysis plan, interim analysis procedures, or the original sample-size justification. These gaps make it difficult to determine which analytic decisions were prespecified and how they may affect interpretation.

15. 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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pneumonia (13.3%), pulmonary embolism (7.1%).

The registry reports serious adverse events affecting 1 participant in the high-dose group, 1 in the low-dose group, and 2 in the sham group. It reports other adverse events affecting 3 participants in the high-dose group, 2 in the low-dose group, and 3 in the sham group. The listed numbers at risk are 14, 13, and 15, respectively. One death is reported in each group.

These counts describe what is recorded for the study groups; they do not by themselves establish whether an event was caused by stimulation or by another aspect of participants' illness or care. The registry lists pneumonia at 13.3% and pulmonary embolism at 7.1% among the top serious adverse event terms, but does not provide an arm-specific breakdown for those terms in the record. The percentages should not be assigned to a particular group or interpreted as comparative risks without additional detail.

Safety comparisons are limited by the small group sizes and by the lack of event-level timing, severity, relatedness, and arm-specific term detail. The registry's event counts should be read descriptively, not as a definitive comparison of safety between stimulation schedules and sham.

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

The primary results estimate average changes in PAS during a short period of stimulation and swallowing exercises. The high-dose and low-dose comparisons with sham have unadjusted mean differences of 0.4 and 0.0, respectively. Their reported intervals span zero, and their unadjusted p-values are 0.444 and 1.0. These results do not show a clear statistical separation between either active schedule and sham in the posted primary summaries.

That finding is not proof that the groups are identical, and it is not proof that no effect is possible. The intervals indicate uncertainty, and the study has small outcome group counts. Nor do the primary results establish that any numerical change is clinically important. The registry does not report a threshold for a meaningful PAS difference. Group averages also do not describe every participant's experience or the full distribution of individual outcomes.

The outcome is an average on an ordinal scale based on 9 swallows, measured over the specified short period. It cannot by itself answer every question about swallowing recovery, dietary intake, longer-term outcomes, or safety. The trial also includes secondary measures, but their mixed results and the absence of a reported multiplicity plan mean they do not overturn the uncertain primary comparisons.

The registry describes a randomized and quadruple-masked study, but does not report details of the randomization or masking procedures, the original sample-size rationale, or a complete statistical analysis plan. The record also does not describe how missing values were handled. Those omissions limit the ability to evaluate potential sources of bias and the robustness of the analyses.

Accordingly, the posted data support a cautious statistical reading: the estimated primary differences are imprecise and do not clearly distinguish the tDCS groups from sham. The results alone do not warrant claims of benefit, lack of benefit, equivalence, or a definitive safety comparison.

17. Why This Trial Matters Statistically

This trial is statistically instructive because it compares two active stimulation schedules with a sham group while measuring change on a clinically relevant but ordinal scale. It makes visible the difference between observing a change within a group and estimating a difference between groups. The sham group also had a mean PAS change, so interpreting active-arm changes in isolation would not answer the comparative question.

The primary comparisons demonstrate why uncertainty matters. The mean differences are point estimates, but their intervals span zero; the results are therefore compatible with more than one direction of group difference. A p-value alone would not convey that range. Reading the estimates, intervals, and group variability together gives a more complete view of what this sample can establish.

The registry also illustrates how secondary outcomes can broaden a trial's descriptive scope while complicating interpretation. Measures of dietary intake and physiology may address different aspects of recovery, but multiple unadjusted comparisons create a risk of chance findings. The pharyngeal-strength comparison with an unadjusted p-value of 0.032 deserves context rather than isolation, particularly when the registry does not report a multiplicity strategy.

Finally, transparency about analysis populations, missing data, prespecified methods, and sample-size assumptions is essential for readers assessing precision and potential bias. The primary outcome is described as intention-to-treat, but implementation details and the original design rationale are not reported in the registry record. These limitations show why a numerical result should be interpreted alongside both the design information and the completeness of the statistical reporting.

18. 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.

Several limitations specific to this record affect interpretation. The enrolled total was 42, divided across three groups, and the posted primary outcome counts are 14, 13, and 15. The resulting estimates have broad uncertainty, as reflected by intervals spanning zero for both primary comparisons. The record does not report the original sample-size justification, so it is not possible to assess the planned sensitivity of the trial to a particular difference.

The primary measure averages an ordinal PAS score over 9 swallows and is summarized with means and standard deviations. The registry does not provide category-level distributions, participant-level outcome data, or a separate ordinal analysis. This limits assessment of whether group averages conceal different patterns across the scale.

The primary outcome is measured over a short interval around stimulation. The registry describes dietary intake assessment after 1 month, but numerical results for all listed secondary outcomes are not available in the record. It does not report longer-term primary PAS comparisons. Nor does the record provide a clinically important difference threshold for interpreting the scale.

Some group counts differ across outcomes, while details of missing-data handling and analysis populations are not reported. The registry also does not give the complete statistical analysis plan, the method used to generate the reported intervals, or a multiplicity strategy for secondary comparisons. These reporting gaps, together with the small sample and multiple outcomes, limit the strength of conclusions that can be drawn from individual estimates.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Fostering Eating After Stroke With Transcranial Direct Current Stimulation — NCT01919112.
• Registry record last updated 2020-07-21; status last verified 2020-07.
• Results first posted 2020-07-07.
• 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.

22. Record Summary

The registry describes a completed randomized, quadruple-masked, parallel trial of high-dose anodal tDCS, low-dose anodal tDCS, and sham stimulation, each assessed alongside swallowing exercises as described for the study arms. Total enrollment was 42. The primary endpoint was change in PAS score, measured before stimulation and after 5 days following completion of stimulation.

The posted primary mean differences versus sham were 0.4 for high-dose tDCS and 0.0 for low-dose tDCS. Both reported intervals span zero. The registry also lists secondary swallowing and dietary outcomes and adverse event counts, but key details about the original design assumptions, analysis procedures, missing data, and multiplicity are not reported in the registry record. The primary comparisons are consequently best understood as uncertain estimates rather than definitive evidence of a difference or equivalence.