Pilot and Feasibility of MEMI for Chronic Traumatic Brain Injury: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pilot and Feasibility of MEMI for Chronic Traumatic Brain Injury (NCT06375421), a non-randomized na study. The primary outcome is Acceptability.

2. Clinical Question

This is a feasibility-focused study, not a randomized comparison. Its central question is whether participants find the mobile-phone-delivered spaced-retrieval approach acceptable, with blocked retrieval serving as an active comparison condition. The additional memory outcomes address whether technology-delivered spaced retrieval opportunities may be associated with differences in memory performance among people with and without chronic traumatic brain injury. The registry record identifies these as preliminary questions; it does not report endpoint values or a conclusion about the memory outcomes.

Because the allocation is non-randomized, comparisons between conditions should be interpreted with attention to order and other possible differences between participants or study periods. The record describes two condition sequences, but does not report how sequence assignment was determined. It also does not report a numerical acceptability result, a statistical comparison between conditions, or details of a primary analysis. The clinical question is therefore best read as an assessment of feasibility and acceptability, with preliminary memory outcomes, rather than as a definitive test of clinical benefit.

3. Trial Design

The registry record describes a completed pilot and feasibility study of MEMI for chronic traumatic brain injury. The study began on 2024-04-03, had a primary completion date of 2024-12-02, and lists enrollment as 40. The listed phase is NA. Vanderbilt University Medical Center is the sponsor.

The design is identified as non-randomized, unmasked, and crossover. Participants complete both a MEMI spaced-retrieval week and a blocked-retrieval week. The record describes an Intervention, then Active Comparator sequence and an Active Comparator, then Intervention sequence. Thus, the condition order differs across the described sequences. The record does not state how participants entered either sequence, so random assignment should not be assumed. No masking is listed.

The study includes participants with traumatic brain injury and non-injured comparison participants. Its stated aim is to examine feasibility and acceptability and to assess preliminary efficacy related to memory. The primary outcome is acceptability. Secondary outcomes are free recall of word forms, cued recall of word forms, and cued recall of word meanings. Six outcome measures and six analyses are listed, but the registry record does not give enough detail to map each analysis to an outcome or to describe the analysis methods.

In a crossover design, the same participant can experience more than one condition, so comparisons may reflect both condition and the order or timing of exposure. This general design feature makes sequence and period effects relevant considerations. The record identifies the crossover structure but does not report analyses of order effects, a washout period, or other design details that would clarify how such effects were handled. The status is completed, but the registry record does not report the numerical primary endpoint result or the detailed memory outcome results in the registry record described for this study.

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.

First Intervention (1 Week)

Reasons for not completing this period:

Second Intervention (1 Week)

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 Acceptability, measured over 1 week in each intervention condition.

The primary endpoint is acceptability, assessed with the Acceptability of Intervention Measure. The registry describes the outcome as a mean score on a scale, with standard deviation as the dispersion measure, after 1 week in each intervention condition. Its stated scale interpretation runs from 4 = completely disagree/not acceptable, described as worse, to 20 = completely agree/acceptable, described as better. A higher score therefore corresponds to greater reported acceptability according to the measure’s stated direction.

Acceptability is relevant in a pilot and feasibility study because an intervention that is difficult to use or unacceptable to participants may be challenging to evaluate further. This is a general reason to assess acceptability; it is not a result about MEMI in this study. The endpoint concerns participants’ reported views of the intervention, rather than a direct measure of memory performance or a clinical outcome.

The registry record does not report the observed mean, standard deviation, or a comparison of acceptability between MEMI and blocked retrieval. It also does not report whether a threshold for acceptable scores was specified. As a result, the endpoint’s definition and direction can be described, but the posted information does not establish how acceptable participants found either condition.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. It also describes a non-randomized crossover design, with participants completing MEMI spaced retrieval and blocked retrieval in one of two orders. These details identify broad features of the study, but the specific statistical model, hypothesis tests, confidence intervals, covariate adjustments, and handling of repeated measurements are not reported in the registry record.

What does a mean describe?

In general, a mean is an average that describes the central level of a quantitative outcome in the observations being summarized. For this study, the primary measure is a scale score for acceptability, and the record states that higher scores indicate greater acceptability. A mean can help describe the overall response, but it does not show whether most participants gave similar ratings or whether responses varied substantially. It also does not establish that one condition differs from another unless the conditions are compared using an appropriate analysis.

What does a standard deviation add?

In general, a standard deviation describes how dispersed individual observations are around their mean. A smaller spread indicates observations are more clustered around the average; a larger spread indicates more variability. The standard deviation is not itself an estimate of the uncertainty in a difference between conditions. To evaluate a comparison, readers generally need an effect estimate and a measure of its uncertainty, such as a confidence interval. The registry record does not report those numerical results for the primary endpoint.

How should the crossover design be understood?

In general, a crossover design has participants experience multiple conditions, with their outcomes considered across those experiences. This can make within-person comparisons useful because stable characteristics of a participant are shared across conditions. However, this design also raises questions about order, period, and carryover effects. A condition experienced first may be followed by changes that affect responses during the next condition, and the study period itself may matter. These are general methodological considerations, not evidence that such effects occurred in this study.

The registry describes two sequences: MEMI followed by blocked retrieval, and blocked retrieval followed by MEMI. It labels allocation non-randomized. The record does not say how participants were assigned to sequences, whether the analysis included sequence or period terms, or whether any washout was used. As a result, the exact statistical handling of the crossover structure cannot be reconstructed from the registry information.

What does non-randomized allocation imply?

In general, random allocation is used to reduce systematic differences between groups or sequences. When allocation is non-randomized, pre-existing differences or selection processes may be related to which condition is experienced first. This can complicate interpretation of a comparison. The study’s crossover structure does not remove the concern automatically, particularly if order is associated with participant characteristics or if outcomes vary across periods. The registry record does not report a method for addressing these possibilities, so no particular adjustment should be assumed.

What can the outcome list tell readers?

The record names acceptability as the primary outcome and lists free recall of word forms, cued recall of word forms, and cued recall of word meanings as secondary outcomes. It also states that six outcome measures and six analyses are listed. The number of listed measures and analyses does not, by itself, indicate which statistical tests were used, whether outcomes were analyzed separately or jointly, or how repeated observations were modeled. Those details are not reported in the registry record.

When multiple outcomes or analyses are considered, multiplicity can affect how readers interpret statistical evidence. In general, testing many questions creates more opportunities for a result to appear noteworthy by chance, unless the analysis plan addresses that issue. The record does not report a multiplicity procedure or identify which analyses, beyond the primary outcome designation, were treated as confirmatory. This does not establish that no such procedure was used; it means the registry record does not report one.

What do planning illustrations mean?

The record describes sample-size planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It specifies that the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not necessarily the design decisions used to enroll participants. The illustrations are not observed power. In general, post-study calculations based on an observed effect do not show the probability that the completed study detected an effect; they are conditional planning exercises and depend on the assumptions used. The listed assumptions do not provide an observed acceptability or memory effect magnitude in the registry record for this account.

The registry record does not report the sample-size justification used when the study was planned, a statistical analysis plan, interim analyses, confidence intervals, or the handling of missing data. Such items should not be inferred from the design label, outcome list, enrollment, or planning assumptions. The methods that can be described with confidence are limited to the stated non-randomized crossover design, the listed outcome summaries, and the planning assumptions recorded in the registry.

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("Participants With Traumatic Brain Injury (TBI) Com", "Non-Injured Comparison Participants Completing Int", "Participants With Traumatic Brain Injury (TBI) Com", "Non-injured Comparison Participants Completing Act")
n   <- c(19, 20, 19, 20)
m   <- c(16.68, 17.55, 15.31, 17.25)
sp  <- c(2.81, 2.18, 4.5, 2.79)
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  Participants With Traumatic Brain Injury (TBI) Com  19  16.680  2.810  15.326  18.034
CARM  Non-Injured Comparison Participants Completing Int  20  17.550  2.180  16.530  18.570
CARM  Participants With Traumatic Brain Injury (TBI) Com  19  15.310  4.500  13.141  17.479
CARM  Non-injured Comparison Participants Completing Act  20  17.250  2.790  15.944  18.556

11. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and six analyses. It identifies acceptability as the primary outcome and lists free recall of word forms, cued recall of word forms, and cued recall of word meanings as secondary outcomes. The record does not explain how the listed analyses map to those outcomes, whether additional measures are included, or whether any outcomes were designated exploratory beyond the stated primary and secondary labels.

When a study evaluates multiple outcomes or statistical tests, multiplicity is a general interpretive concern: the more questions assessed, the greater the opportunity for chance findings. Researchers may use a prespecified hierarchy or an adjustment procedure, but the registry record does not report whether such a strategy was used. It also does not report a statistical analysis plan, so the prespecification of analyses cannot be assessed from this record.

Missing-data methods and analysis populations are not reported in the registry record. The enrollment entry does not establish how many observations were available for each outcome, whether anyone discontinued or missed an assessment, or whether all participants were included in every analysis. The record does not state whether missing values were imputed, excluded, or handled using a model-based approach. Those distinctions can affect both the estimated result and its uncertainty.

These omissions limit interpretation of the numerical evidence, even though the study status is completed. Without reported outcome summaries and analysis details, readers cannot assess the extent of missingness, the analysis population, or the effect of multiplicity handling. The absence of these details in the registry record should not be taken to mean that a particular method was or was not used.

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 adverse-event counts separately for participants with traumatic brain injury completing MEMI, non-injured comparison participants completing MEMI, participants with traumatic brain injury completing blocked retrieval, and non-injured comparison participants completing blocked retrieval. In each of these reported groups, 19 participants were listed as at risk for serious adverse events and 0 serious events were reported. In each group, 19 were listed as at risk for other adverse events and 0 other events were reported. Deaths are listed as 0 in each group.

These are the registry’s reported counts for the named groups and conditions. A count of 0 means that no events were recorded in that category in the registry entry; it does not establish that an event is impossible or that risk is absent. The counts also do not describe the kinds of non-serious events that might have been assessed, since no other adverse-event terms are listed in the record.

The record does not provide additional information about how adverse events were collected, the duration of safety monitoring, or how event severity and relatedness were determined. The reported counts should therefore be read as the posted safety summary, not as a complete characterization of every possible safety outcome.

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

This study is designed to examine feasibility and acceptability of a mobile-phone-delivered spaced-retrieval intervention for memory, with blocked retrieval as an active comparator. It also addresses preliminary memory questions in participants with chronic traumatic brain injury and non-injured comparison participants. The primary endpoint is acceptability, while the listed secondary outcomes assess recall of word forms and word meanings.

The registry record does not report the numerical primary endpoint result or results for the secondary memory outcomes in the registry record for this account. It therefore does not support a statement about whether acceptability scores favored either condition, how large any difference was, or how precisely it was estimated. It also does not establish a memory effect or a clinical benefit. The study’s stated aim to assess preliminary efficacy describes a research question, not a conclusion.

The design provides useful context for interpreting future or posted results. Participants complete both conditions in different orders, but allocation is non-randomized and no masking is listed. In general, order, period, and participant differences can influence comparisons in such a design. The registry record does not report whether those factors were assessed or adjusted for in the analyses. Its design should not be interpreted as a randomized comparison.

Completion status and enrollment describe the study’s administrative status and planned or recorded enrollment, not the amount or quality of outcome evidence. The record does not report analysis populations, missing-data handling, confidence intervals, or the statistical analysis plan. Those details would be needed to judge the robustness and precision of reported estimates.

Overall, the registry information establishes what the study set out to assess, how the two conditions were arranged, and which outcomes were named. It does not establish what the outcome scores were or whether one condition differed from the other. Any interpretation should keep that distinction between the research question and a reported result in view.

14. Why This Trial Matters Statistically

This trial is statistically interesting because it combines a feasibility question with a preliminary comparison of two memory-retrieval approaches. Acceptability is a distinct outcome from memory performance: it addresses participants’ assessment of the intervention, while the secondary outcomes concern recall. Separating these questions helps prevent an acceptability measure from being treated as evidence about memory, or memory performance from being treated as evidence that an intervention is feasible or acceptable.

The crossover structure also creates a useful methodological teaching point. In general, observing participants under more than one condition can support comparisons that account for stable differences between individuals. But condition order and time can also matter, and the non-randomized allocation means sequence differences cannot automatically be treated as random. The registry describes the sequences without reporting how sequence assignment or its possible effects were handled.

The study’s stated pilot and feasibility purpose is another important context. A pilot study can help assess whether measures and procedures are workable and can generate information for later research. It is not, by that label alone, evidence that a treatment has a reliable effect. The registry record does not report a sample-size justification or detailed analysis plan, so the planned role of the enrollment cannot be assessed from the information recorded.

Finally, the distinction between an outcome definition and an outcome result is central. The registry specifies the acceptability scale and its direction, and names the memory outcomes, but numerical outcome findings are not reported in the registry record described for this account. Statistical interpretation requires estimates and information about uncertainty, not only a study aim or a list of endpoints. This record therefore offers design and measurement context, while leaving the primary empirical question unanswered in the posted information.

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 gives limited detail about participant eligibility beyond identifying adults with chronic traumatic brain injury and non-injured comparison participants. It does not report the specific inclusion and exclusion criteria, participant characteristics, recruitment approach, or how the comparison participants were selected. These omissions make it difficult to judge how broadly the study population represents people who might be considered for future research.

The design is non-randomized and unmasked. The two described sequences vary in condition order, but the method for assigning participants to sequence is not reported. The record also does not state whether order, period, or carryover effects were evaluated. These are relevant design limitations for interpreting condition comparisons, though the registry does not establish whether any such effects occurred.

The primary endpoint is described, but observed acceptability values are not reported in the registry record. Numerical findings for the memory outcomes are also absent. Without estimates, dispersion, uncertainty intervals, and analysis details, the size and precision of any outcome pattern cannot be assessed. The registry record does not report how missing data were handled, which participants entered each analysis, or whether all planned outcomes were analyzed.

Finally, the study is identified as a pilot and feasibility study with a preliminary efficacy aim. The record does not report a sample-size justification, detailed statistical plan, or multiplicity procedure. The listed planning assumptions are not a substitute for those design and analysis details, and planning illustrations are not observed power. These limitations concern what can be concluded from the registry record; they do not establish what methods may have been used outside the reported record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Pilot and Feasibility of MEMI for Chronic Traumatic Brain Injury — NCT06375421.
• Registry record last updated 2026-01-06; status last verified 2025-12.
• Results first posted 2026-01-06.
• 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 identifies NCT06375421 as a completed, non-randomized, unmasked crossover pilot and feasibility study sponsored by Vanderbilt University Medical Center. The study concerns MEMI spaced retrieval for adults with chronic traumatic brain injury and includes non-injured comparison participants. Enrollment is listed as 40. The study began on 2024-04-03, and the primary completion date is 2024-12-02.

Participants complete MEMI spaced retrieval and blocked retrieval in one of two described orders. Acceptability is the primary outcome, measured with the Acceptability of Intervention Measure after 1 week in each condition. The listed secondary outcomes are free recall of word forms, cued recall of word forms, and cued recall of word meanings.

The registry record does not report the primary endpoint result, numerical memory outcome results, analysis populations, missing-data methods, or a detailed statistical analysis plan. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each of the four listed safety groups.