This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for tDCS in Elderly Fallers Study (NCT03814304), a randomized na study. The primary outcome is Change From Baseline in the Dual Task Cost to Gait Speed.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03814304 |
| Phase | NA |
| Condition | Accidental Falls, Aging |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 99 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Hebrew SeniorLife |
| Results posted | Yes |
2. Clinical Question
Population
Older adults who reported two or more falls within the past year and fear of falling again in the future were the intended population. The registry also describes excluding people with an acute or other neurological or musculoskeletal condition. The primary outcome record does not give a separate population description, so the number included in the primary analysis is not reported in the registry record.
Intervention
The active intervention was transcranial direct current stimulation (tDCS), designed to facilitate excitability in the left dlPFC. The study summary describes a four-week, 20-session intervention. The registry's description of the stimulation protocol is incomplete, so further session and dosing details are not reported in the registry record.
Comparator
The comparison was an active-sham intervention. The registry describes very low-level currents transferred between nearby scalp electrodes during the session. This comparator was intended to be optimized for participants and designed not to produce the intended stimulation effect; further details are not reported in the registry record.
Primary question
The primary question was whether change from baseline in the dual-task cost to gait speed differed between tDCS and active sham. The measure concerns how much gait speed changes when walking is combined with a serial-subtraction task, compared with walking alone. The intended follow-up time points were 3-day, 3-month, and 6-month follow-up. The primary outcome results are not reported in the registry record.
3. Trial Design
The registry describes a randomized, triple-masked, parallel-group trial comparing tDCS with active sham. Randomization means assignment to the study interventions was intended to occur by chance; masking means that some people involved in the trial were intended not to know the assigned intervention. Which specific groups were masked, and how masking was maintained or assessed, are not reported in the registry record. Allocation concealment details are also not reported in the registry record.
The registry lists enrollment as 99 and status as completed. The recorded start date is 2019-07-08, and the primary completion date is 2025-01-24. These registry fields describe enrollment and trial status, not the number of people contributing data to each outcome analysis. Analysis group sizes and analysis-population definitions are not reported in the registry record.
The intervention summary describes four weeks and 20 sessions. The study focused on older adults reporting two or more falls in the past year and fear of falling again, without an acute or other neurological or musculoskeletal condition. The active-sham description refers to low-level currents between nearby scalp electrodes. Details such as adherence, intervention fidelity, and whether participants received all intended sessions are not reported in the registry record.
The primary outcome is a continuous measure of change from baseline in dual-task cost to gait speed, expressed as a percentage. The outcome timeframe lists 3-day, 3-month, and 6-month follow-up. The registry also describes physical and cognitive endpoints, including the Short Physical Performance Battery and Trail Making Test B minus A, as well as other gait, balance, and cognitive measures. The phase is listed as NA. The registry does not report the statistical analysis plan, the primary analysis population, or a single selected follow-up comparison.
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
| Stage | tDCS | Active-Sham |
|---|---|---|
| STARTED | 50 | 49 |
| COMPLETED | 48 | 43 |
| NOT COMPLETED | 2 | 6 |
Reasons for not completing this period:
| Reason | tDCS | Active-Sham |
|---|---|---|
| Lost to Follow-up | 1 | 3 |
| Adverse Event | 1 | 3 |
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.
| Characteristic | Unit | tDCS | Active-Sham | Total |
|---|---|---|---|---|
| Participants analysed | 48 | 43 | 91 | |
| Age, Continuous | years | 80 (SD 7) | 78 (SD 7) | 79 (SD 7) |
| Sex: Female, Male: Female | Participants | 30 | 27 | 57 |
| Sex: Female, Male: Male | Participants | 18 | 16 | 34 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 6 | 2 | 8 |
| Race (NIH/OMB): White | Participants | 41 | 41 | 82 |
| Race (NIH/OMB): More than one race | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| BMI | kg/m^2 | 30 (SD 6) | 29 (SD 6) | 29 (SD 6) |
| Clinical Dementia Rating (CDR): CDR=0 | Participants | 38 | 29 | 67 |
| Clinical Dementia Rating (CDR): CDR=0.5 | Participants | 10 | 14 | 24 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in the Dual Task Cost to Gait Speed, measured over 3-day follow-up; 3-month follow-up; 6-month follow-up.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | percentage |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change from baseline in the dual-task cost to gait speed, expressed as a percentage. The dual-task cost compares gait speed while walking and performing serial subtraction with gait speed while walking alone. The registry defines the measure using the difference between dual-task and single-task speed relative to single-task speed, multiplied by 100. A greater reduction in this cost from baseline to after the intervention is described as better performance.
This measure captures performance when walking is paired with a cognitive task, rather than gait speed in isolation. That distinction matters because the study's question concerns dual-task walking: a situation in which attention is divided between movement and another task. The endpoint therefore combines a walking measure with a cognitive demand. It is one of the planned outcomes for the study's first aim, which concerns dual-task standing and walking performance.
Change from baseline expresses how a participant's measured outcome differs from their starting value. Comparing change between randomized groups can help address whether the groups' outcome trajectories differed during the trial, subject to the analysis methods and data available. The registry identifies 3-day, 3-month, and 6-month follow-up time points, but does not report which time point was designated as the single primary comparison. No group means, standard deviations, effect estimate, confidence interval, or significance test for this endpoint are reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the intended primary outcome and its measurement schedule, but does not report the primary outcome results. In particular, it does not report group-specific means or changes, a between-group estimate, a confidence interval, or a p-value for change in dual-task cost to gait speed. The posted information therefore does not establish the size, direction, or precision of any difference between tDCS and active sham on this endpoint.
The endpoint is defined so that a greater reduction from baseline in dual-task cost is described as better performance. That description explains how to interpret the direction of the measure, but it is not a result. Without outcome estimates, it is not possible to determine whether either group changed, whether the groups changed differently, or how compatible the data might be with effects of different sizes. The planned follow-up time points are 3-day, 3-month, and 6-month follow-up; results at those time points are not reported in the registry record.
The registry records safety information for both groups. For tDCS, serious adverse events are recorded as 12 affected among 50 at risk, and other adverse events as 45 affected among 50 at risk; deaths are recorded as 1. For active sham, serious adverse events are recorded as 7 affected among 49 at risk, and other adverse events as 36 affected among 49 at risk; deaths are recorded as 0. These are descriptive registry counts. The record does not provide an analysis comparing adverse-event risk between the groups, or enough detail to establish event timing, severity beyond the serious/non-serious classification, or whether individual events were judged related to the intervention.
The registry lists serious-event terms with percentages, including suicidal ideation at 4.1%, and fall, hip fracture, headache, transient ischaemic attack, and proctectomy each at 2.0%. It does not identify the treatment group for each listed term in the information recorded. These percentages should therefore be read as registry-listed event information, not as group-specific comparative estimates.
The trial is marked completed, but completion status is not a substitute for results. The number of outcome measures and analyses recorded does not reveal which analyses were prespecified, how missing measurements were handled, or whether any result was statistically persuasive. Those details are not reported in the registry record. The main statistical interpretation is consequently limited: the record describes the question and some safety counts, while the primary efficacy comparison remains unreported.
9. Statistical Methods Explained
The registry characterizes the primary endpoint as the mean of a continuous measure with standard deviation as its dispersion. A continuous measure can take values across a scale rather than belonging to a small set of categories. A mean describes the center of a set of measurements, while a standard deviation describes their spread around that center. Together, those summaries can help readers understand both the average outcome and how variable the measurements are. The registry does not report the primary outcome means or standard deviations.
What does change from baseline represent?
A change score expresses an outcome relative to its baseline measurement. In this trial, the endpoint is change from baseline in dual-task cost to gait speed. Baseline adjustment can make the comparison focus on how the outcome moved during follow-up rather than on follow-up values alone. However, the exact statistical model used to compare groups, including whether it adjusted for baseline values or other covariates, is not reported in the registry record. The definition of an endpoint does not, by itself, identify the model used to analyze it.
How should the dual-task cost be understood?
The dual-task cost relates walking speed during serial subtraction to walking speed during single-task walking. It is expressed as a percentage using the single-task speed as the reference. This puts the change in speed in relation to the person's single-task speed, rather than treating the speed difference as an unscaled quantity. The registry states that a greater reduction in dual-task cost from baseline indicates better performance. That interpretation describes the measure's direction; it does not provide an estimate of what happened in either group.
What do a confidence interval and a p-value tell readers?
In general, a confidence interval describes a range of values compatible with an estimate under the assumptions of the analysis. Its width conveys precision: a narrower interval indicates more precision than a wider interval, while both the location and width matter for interpretation. A p-value describes how unusual data at least as incompatible with a specified null hypothesis would be under the model assumptions. Neither measure alone describes clinical importance, and neither can replace seeing the estimated effect and its uncertainty. No confidence interval or p-value for the primary comparison is reported in the registry record.
What does randomization contribute?
In general, random assignment is intended to make treatment groups comparable at the point of assignment, including with respect to factors that may not have been measured. It does not guarantee that every characteristic is balanced in a particular trial, and it does not prevent bias from missing outcomes, departures from assigned treatment, or analysis choices. The record identifies the trial as randomized but does not report the method used to generate assignments, allocation concealment, baseline balance results, or the analysis population. The practical strength of the randomized comparison therefore cannot be fully assessed from those fields alone.
How should the follow-up schedule affect interpretation?
The primary outcome timeframe includes 3-day, 3-month, and 6-month follow-up. Measurements at different times can answer different questions about early change and later outcome patterns. A trial with multiple time points needs a clearly stated analysis strategy, since selecting or emphasizing one time point after results are known can affect interpretation. Which time point was the primary inferential comparison, how repeated measurements were modeled, and whether any adjustment was made for multiple time points are not reported in the registry record.
What can planning calculations say?
Sample-size planning calculations are illustrations of how many participants per arm might be needed under specified assumptions. They depend on assumptions about the effect to detect, variability, significance level, allocation, and statistical method. They are not observed power and do not describe the precision actually achieved in a completed trial. The registry's planning description refers to a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects defined as fractions of the observed effect; it distinguishes participants per arm for ordinary outcomes from total events for time-to-event outcomes. No planning estimates are included in the record details available for this analysis, and the trial's own design justification is not reported in the registry record.
Over-dispersion is a general issue when the observed variability exceeds what a simple statistical model assumes. In such cases, standard errors can be too small if the model does not account for the extra variation, making confidence intervals too narrow and tests too optimistic. This concept is relevant to choosing models for some outcomes, but the primary endpoint is recorded as a continuous mean measure, and the registry does not report whether over-dispersion was considered or any model diagnostics. No claim about over-dispersion in this trial can be made from the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 17 outcome measures and 16 analyses. The primary outcome has a timeframe of 3-day, 3-month, and 6-month follow-up. The study summary also describes several primary endpoints across physical and cognitive aims, alongside secondary measures covering falls efficacy, cognition, physical performance, gait, balance, and other tests. Considering multiple outcomes and time points can create multiplicity: the more comparisons examined, the greater the chance that at least one result appears notable by chance alone, if no adjustment or prespecified hierarchy is used.
Whether the investigators controlled the overall error rate, used a hierarchical testing strategy, designated one time point as primary, or treated other comparisons as exploratory is not reported in the registry record. The record also does not report whether analyses were prespecified before unmasking or how outcome measures were prioritized in interpretation. The count of measures and analyses does not answer those questions.
Missing-data methods are not reported in the registry record. The numbers of participants with measured primary outcomes at each follow-up, reasons for missing measurements, and any imputation or sensitivity analyses are also not reported. Without those details, it is not possible to assess whether missing outcomes could have influenced the estimated treatment contrast.
Analysis populations are not reported in the registry record. In particular, the record does not specify whether the primary analysis included everyone as randomized, only participants who completed the intervention, or another defined group. The enrolled count and safety at-risk counts should not be treated as the analysis denominators for the primary endpoint. These gaps limit interpretation of both the statistical error control and the representativeness of any outcome estimate; no primary estimate is reported in the registry record to evaluate.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| tDCS | 12 | 50 | 24.0% |
| Active-Sham | 7 | 49 | 14.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| tDCS | 1 of 50 |
| Active-Sham | 0 of 49 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| tDCS | 45 of 50 |
| Active-Sham | 36 of 49 |
Most frequent serious adverse event terms
| Event term | Organ system | tDCS | Active-Sham |
|---|---|---|---|
| Suicidal ideation | Psychiatric disorders | 1 of 50 | 2 of 49 |
| Fall | Injury, poisoning and procedural complications | 1 of 50 | 1 of 49 |
| Hip fracture | Injury, poisoning and procedural complications | 1 of 50 | 1 of 49 |
| Atrial fibrillation | Cardiac disorders | 1 of 50 | 0 of 49 |
| Death | General disorders | 1 of 50 | 0 of 49 |
| COVID-19 | Infections and infestations | 1 of 50 | 0 of 49 |
| Gastroenteritis paracolon bacillus | Infections and infestations | 1 of 50 | 0 of 49 |
| Influenza | Infections and infestations | 1 of 50 | 0 of 49 |
| Muscle strain | Injury, poisoning and procedural complications | 1 of 50 | 0 of 49 |
| Headache | Nervous system disorders | 0 of 50 | 1 of 49 |
Most frequent non-serious adverse event terms
| Event term | Organ system | tDCS | Active-Sham |
|---|---|---|---|
| Fall | Injury, poisoning and procedural complications | 34 of 50 | 27 of 49 |
| COVID-19 | Infections and infestations | 7 of 50 | 6 of 49 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 7 of 50 | 4 of 49 |
| Headache | Nervous system disorders | 4 of 50 | 4 of 49 |
| Nasopharyngitis | Infections and infestations | 5 of 50 | 3 of 49 |
| Dizziness | Nervous system disorders | 4 of 50 | 3 of 49 |
| Back pain | Musculoskeletal and connective tissue disorders | 5 of 50 | 1 of 49 |
| Balance disorder | General disorders | 4 of 50 | 2 of 49 |
| Diarrhea | Gastrointestinal disorders | 2 of 50 | 4 of 49 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 4 of 50 | 1 of 49 |
Serious events with the highest arm-level rate: suicidal ideation (4.1%), fall (2.0%), hip fracture (2.0%), headache (2.0%), transient ischaemic attack (2.0%).
The registry reports serious and other adverse-event counts separately for tDCS and active sham. In the tDCS group, 12 were recorded as affected by serious adverse events among 50 at risk; 45 were recorded as affected by other adverse events among 50 at risk. The registry records 1 death in this group. In the active-sham group, 7 were recorded as affected by serious adverse events among 49 at risk; 36 were recorded as affected by other adverse events among 49 at risk. The registry records 0 deaths in this group.
These counts describe the entries in the safety record; they are not, on their own, a causal comparison. The registry information does not specify the event-level timing, recurrence, duration, or attribution to intervention, and it does not report a statistical comparison of safety outcomes between groups. Serious and other adverse events are separate categories in the record and should not be combined. The listed serious-event terms include suicidal ideation at 4.1%, and fall, hip fracture, headache, transient ischaemic attack, and proctectomy each at 2.0%. The record information does not assign these listed terms to a particular group, so they should not be read as group-specific percentages.
12. What the Result Does, and Does Not, Mean
The registry record answers some design questions: it describes a randomized, triple-masked, parallel comparison of tDCS with active sham in older adults meeting the stated fall-history and fear-of-falling criteria. It also defines the planned primary outcome as change from baseline in dual-task cost to gait speed and names the follow-up time points. These details explain what the trial was intended to investigate, but they do not establish the observed effect.
The primary outcome results are not reported in the registry record. As a result, the direction and magnitude of the group contrast, its precision, and the compatibility of the data with different effect sizes cannot be evaluated. The endpoint's stated favorable direction is not evidence that the intervention changed the endpoint, and completion status does not supply an efficacy result. No conclusion about benefit or lack of benefit follows from the information recorded.
The safety fields contain descriptive counts for serious events, other events, and deaths by group. They do not provide event attribution or an inferential comparison. A difference between raw counts would not by itself show that assignment caused a difference, especially without a defined analysis, event timing, and fuller information about who contributed data. The listed serious-event terms also cannot be assigned to a group from the record information.
More generally, an observed estimate would need to be interpreted together with its uncertainty, the analysis population, outcome completeness, and the handling of multiple outcomes and time points. Those elements are not reported in the registry record. Statistical significance, if reported elsewhere, would not alone establish practical importance; conversely, a non-significant result would not alone demonstrate equivalence. Here, no primary estimate or test is reported, so the appropriate interpretation is that the trial's primary comparative result is unavailable in this registry record, rather than that a particular treatment effect has been demonstrated or ruled out.
13. Why This Trial Matters Statistically
This trial raises a statistical question about a functional outcome measured under divided attention. Walking while performing serial subtraction is different from measuring walking alone, and the dual-task cost expresses that difference relative to single-task gait speed. This makes the endpoint specific to the kind of combined physical and cognitive performance described in the study aims. It also means the result cannot be inferred from a general measure of gait, balance, or cognition alone.
The randomized, parallel-group design is intended to support a comparison between tDCS and active sham. The active comparator is relevant to interpretation because the question is framed as a contrast with another intervention condition, not simply a comparison with no session. The registry describes triple masking, but does not specify which people were masked or report whether masking was successful. Those details matter when assessing the potential for expectation or assessment effects.
The planned follow-up schedule spans early and later measurements, making the analysis strategy important. A clear account of the selected primary time point, repeated-measure approach, missing outcomes, and multiplicity would help readers distinguish a prespecified central result from secondary or exploratory findings. Those statistical details are not reported in the registry record.
The record also illustrates the distinction between a completed trial and a complete statistical account. Enrollment and safety counts are recorded, while the primary outcome estimates are not reported. Without an effect estimate and its uncertainty, neither the size nor precision of the primary comparison can be judged. The study's statistical importance therefore lies in the focused question and outcome definition, alongside the need for transparent reporting of the analysis and results; the registry information alone does not resolve the efficacy question.
14. 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 main limitation for interpreting this trial from the registry record is that the primary outcome result is not reported. There are no group-specific outcome summaries, between-group estimate, confidence interval, or p-value. Although the endpoint's definition and follow-up schedule are recorded, they are not enough to assess the size, direction, or precision of the comparison.
The analysis plan is not reported in the registry record. Details about the primary analysis model, adjustment for baseline, treatment of repeated measurements, and selection among the listed follow-up times are therefore unavailable. The record also does not describe multiplicity control, missing-data handling, or the population used in the primary analysis. These omissions prevent assessment of how analysis decisions may have affected the reported evidence.
The registry describes the population criteria and the randomized, triple-masked, parallel design, but does not report assignment-generation or concealment procedures, baseline balance, masking success, adherence, or intervention fidelity. It also does not report how many participants contributed primary-outcome measurements at each follow-up. Enrollment and adverse-event denominators cannot substitute for those outcome-analysis details.
Safety information is recorded as counts, but event timing, recurrence, severity details beyond the serious/non-serious classification, and intervention attribution are not reported in the registry information. The listed serious-event terms are not linked to a treatment group in that information. These constraints mean the safety counts should be treated as descriptive rather than as a comparative causal analysis.
The registry marks the study completed and lists multiple outcomes and analyses, but does not provide the statistical context needed to evaluate a primary result. The absent details do not show that a particular method was or was not used; they are simply not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: tDCS in Elderly Fallers Study — NCT03814304.
- Registry record last updated 2026-07-28; status last verified 2026-07.
- Results first posted 2026-07-28.
- 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.
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18. Record Summary
NCT03814304, titled tDCS in Elderly Fallers Study, is listed as a completed randomized, triple-masked, parallel-group trial sponsored by Hebrew SeniorLife. The registry records enrollment of 99, a start date of 2019-07-08, and a primary completion date of 2025-01-24. The comparison is tDCS versus active sham in older adults described as having recurrent falls and fear of falling.
The primary outcome is change from baseline in dual-task cost to gait speed, with 3-day, 3-month, and 6-month follow-up listed. The primary outcome results and the statistical analysis plan are not reported in the registry record. Safety counts are recorded for serious events, other events, and deaths in both groups, but no comparative safety analysis is reported. Missing-data methods, analysis populations, and multiplicity procedures are not reported in the registry record.