Evaluating The Efficacy And Safety Of Donepezil Hydrochloride (HCl) (Aricept) In Treating Cognitive Dysfunction Exhibited By Children With Down Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluating The Efficacy And Safety Of Donepezil Hydrochloride (HCl) (Aricept) In Treating Cognitive Dysfunction Exhibited By Children With Down Syndrome (NCT00570128), a randomized phase 2 study. The primary outcome is Mean Change From Baseline in V-Scale Composite Score (Sum of 9 Sub-Domains) of Vineland Adaptive Behavior Scales Second Edition-Parent Caregiver Rating Form (VABS-II/PCRF) at Week 10-Last Observation Carried Forward (LOCF).

2. Clinical Question

3. Trial Design

This was a phase 2, randomized, double-blind, placebo-controlled, parallel-group study of donepezil HCl for cognitive dysfunction in children with Down syndrome. The registry record lists enrollment as 129. The study is marked completed. Its recorded start date is 2007-11-16, and its primary completion date is 2008-09-05. The official title describes a 10-week study.

Participants were assigned to donepezil HCl or placebo. The record identifies the trial as randomized and double-masked, but does not report details about sequence generation, allocation concealment, or how masking was maintained. Arm descriptions do not include the dose, administration schedule, or other treatment procedures. These details are not reported in the registry record.

The study population of interest was children and adolescents aged 10 to 17 with Down syndrome. The stated purpose was to evaluate efficacy and safety, with effectiveness assessed through ratings of communication, daily living skills, and social skills and relationships. The primary endpoint was a caregiver-rated adaptive-functioning score at Week 10; secondary outcomes included caregiver-rated V-scale changes at Week 4 and Week 10 and verbal-expression and reasoning scores.

The registry record does not report a sample-size justification, a statistical analysis plan, interim analyses, or details of the primary comparison. No outcome analyses are listed. As a result, the design can be described from its registry fields, but the planned inferential approach and the trial’s efficacy findings cannot be reconstructed from this 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: ITT population: all randomized participants who received at least one dose of study drug and had at least one post-baseline assessment for at least one efficacy variable irrespective of compliance and protocol violations. Here "Overall number of participants analyzed, N" signifies participants who were evaluable for this outcome measure.

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 Mean Change From Baseline in V-Scale Composite Score (Sum of 9 Sub-Domains) of Vineland Adaptive Behavior Scales Second Edition-Parent Caregiver Rating Form (VABS-II/PCRF) at Week 10-Last Observation Carried Forward (LOCF), measured over Baseline, Week 10.

The primary endpoint was mean change from baseline to Week 10 in the composite V-scale score on the Vineland Adaptive Behavior Scales Second Edition Parent Caregiver Rating Form (VABS-II/PCRF), using LOCF. The composite combines standardized scores across communication, daily living skills, and socialization. Each domain includes receptive, expressive, and writing; personal, domestic, and community; or interpersonal relationships, play/leisure time, and coping skills, respectively.

Caregivers rated raw behaviors using categories described in the record, and the sub-domain results were converted to age-based standardized V-scores. The composite is formed from the nine sub-domain scores and ranges from 9 to 216. Higher scores indicate higher adaptive functioning, and a positive change from baseline indicates improvement on this measure. These are properties of the instrument, not evidence of a treatment effect.

A caregiver-rated adaptive-functioning measure is relevant to the study’s stated focus on everyday communication, daily living, and social skills. It captures functioning across areas that matter to the study question rather than relying only on a test of verbal reasoning. However, interpretation depends on the rating process and on the analysis population and missing-data approach. The registry record does not report endpoint values, variability, a treatment contrast, or its uncertainty, so it does not establish the magnitude or precision of any difference between groups.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is a continuous score, and the registry record identifies its summary measure as a mean with standard deviation. In general, a mean describes the average score in a group, while a standard deviation describes how spread out individual scores are around that average. Neither statistic is reported for the primary endpoint, so the record does not allow readers to assess the observed score distribution or its variability.

The stated primary outcome is change from baseline, rather than the Week 10 score alone. In general, change scores express how a measure differs from a participant’s starting value. A comparison of average changes between randomized groups can address whether change differed between groups, but it needs the group-level results and an appropriate uncertainty estimate. Those results are not reported in the registry record. No recalculated comparison is available from the posted information.

The endpoint uses the VABS-II/PCRF composite. Its component V-scores are age-based standardized scores, and the composite sums the nine sub-domain scores. The record states that the composite ranges from 9 to 216, with higher scores indicating higher adaptive functioning. In general, a composite can summarize related aspects of functioning, while also making it important to understand which domains contribute to the total. The registry description explains the components, but does not report results by domain or sub-domain.

LOCF means Last Observation Carried Forward. In general, this approach substitutes a participant’s last available observation for a later missing measurement. It can retain participants without a Week 10 measurement in an analysis, but it assumes that the carried-forward value is a suitable representation of the unobserved later value. That assumption may not hold when a participant’s status would have changed after the last observation. LOCF can also make uncertainty appear smaller or larger than it would under other missing-data assumptions. The registry record does not report how many measurements were missing, why they were missing, or any sensitivity analyses examining alternative assumptions.

The secondary outcomes distinguish observed-case and LOCF analyses. In general, an observed-case analysis uses available measurements at the specified assessment and does not fill in missing values. Its interpretation can be affected if the participants with observed data differ systematically from those without them. The record names observed-case analyses for VABS-II/PCRF change at Week 4 and Week 10 and for TOVER change at Week 4; it names LOCF for the TOVER Week 10 outcome. It does not report the results or missing-data patterns for these analyses.

The primary outcome is described at Week 10, while the secondary outcomes include more than one outcome and assessment time. In general, testing multiple outcomes or time points raises a multiplicity question: the chance of at least one apparently notable result can increase when many comparisons are considered. The registry record does not report a multiplicity adjustment or a prespecified hierarchy for interpreting these measures. This does not show that no adjustment was used; the method is not reported in the registry record.

The record identifies a randomized, double-blind, parallel-group design. In general, random allocation is intended to make treatment groups comparable at the start, and masking is intended to reduce the influence of treatment knowledge on care, ratings, or assessment. These design features do not remove the need to report the analysis, outcome estimates, and uncertainty. The record does not give technical details of randomization or masking, so their implementation cannot be evaluated from the registry entry.

The sample-size assumptions describe a planning illustration based on an observed effect: two-sided significance level 0.05, equal allocation, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. The record does not provide the resulting planning figures in the registry record for this analysis, and they are not trial results. Such sample sizes are planning illustrations, not observed power. The trial’s own sample-size justification and statistical plan are not reported in the registry record.

Finally, an inferential comparison would ordinarily be interpreted using both an effect estimate and its uncertainty. In general, a confidence interval expresses a range of values compatible with the data under the analysis assumptions; it helps distinguish a precise estimate from one with substantial uncertainty. A p-value addresses compatibility with a specified null model, but does not measure clinical importance. Neither a confidence interval nor a p-value for the primary endpoint is reported in the registry record. Without these, no claim about statistical precision or strength of evidence can be made from the endpoint results.

10. Multiplicity, Missing Data and Analysis Populations

The registry record names several outcomes and assessment times. The primary measure is VABS-II/PCRF composite change from baseline to Week 10 using LOCF. Secondary measures include V-scale composite change at Week 4 and Week 10 using observed cases, and TOVER total-score change at Week 4 and Week 10, with the specified analysis differing by outcome. Considering more than one outcome or time point can raise multiplicity concerns. In general, multiplicity procedures or a prespecified testing hierarchy can help control how results across comparisons are interpreted. Such procedures are not reported in the registry record.

The record does not provide a statistical analysis plan, interim-analysis details, or outcome analyses. It therefore does not establish whether any multiplicity adjustment or other prespecified strategy was used. Nor does the presence of multiple outcome definitions establish that each was tested or that any result was statistically significant.

The primary outcome uses LOCF, while some secondary outcomes are defined as observed-case analyses. In general, missing-data methods rely on assumptions about the unobserved values. Carrying forward a previous observation and analyzing only observed measurements address missingness differently, and either approach can be sensitive to why data are missing. The registry record does not report the extent or reasons for missing assessments, or sensitivity analyses.

The stated efficacy population includes randomized participants who received at least one dose and had at least one post-baseline assessment for at least one efficacy variable, regardless of compliance and protocol violations. The number analyzed for the primary outcome and the number contributing to each secondary analysis are not reported in the registry record. Therefore, the relationship between randomized participants and the analysis sets cannot be assessed for each endpoint.

11. 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 2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: gastroenteritis (1.5%), dehydration (1.5%).

The registry record reports serious adverse events for the donepezil HCl and placebo groups separately. The serious-event fields show 0 of 64 participants at risk in the donepezil HCl group and 1 of 65 at risk in the placebo group. The record reports 0 deaths in each group. Other adverse events were reported for 45 of 64 participants at risk in the donepezil HCl group and 42 of 65 at risk in the placebo group.

These fields are counts of participants with reported events relative to the corresponding number at risk, not a measure of how severe every event was or how long participants were observed. The registry record also lists gastroenteritis and dehydration among the top serious-event terms, each with a reported percentage of 1.5%. It does not identify the group for those terms in the information, so they should not be assigned to an arm.

In general, safety counts are descriptive unless accompanied by a comparative analysis and relevant context, including event definitions, timing, exposure, and follow-up. The figures do not establish that treatment caused an event or that an event was unrelated to treatment. The registry record does not report a statistical comparison of safety outcomes or details that would support a fuller assessment.

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

The registry record establishes that this was a randomized, double-blind, placebo-controlled phase 2 study of donepezil HCl in children and adolescents with Down syndrome. It defines a caregiver-rated adaptive-functioning endpoint and reports selected adverse-event counts. It does not provide numerical results for the primary or secondary efficacy outcomes. Consequently, the posted information cannot show the size or direction of an efficacy difference between the groups, or how precisely such a difference was estimated.

The endpoint description clarifies what a score would mean: higher composite V-scores indicate higher adaptive functioning, and positive change from baseline indicates improvement on the measure. This direction is not a finding about the trial. Without group-specific changes and a between-group comparison, it is not possible to infer whether either group’s scores changed or whether their changes differed.

The safety counts are also limited in what they establish. They report serious and other adverse events and deaths by group, but the record does not provide a comparative safety analysis or sufficient context to assign causality. The serious-event terms and percentages should be read as registry listings, not as proof of a treatment effect.

In general, a trial result is best interpreted using the estimated effect, its uncertainty, the analysis population, and the assumptions behind handling missing data and multiple outcomes. Those elements are not available for the primary comparison in this record. This absence does not demonstrate that the treatment had no effect, nor does it demonstrate that it did. It means the registry information is insufficient to establish either conclusion.

The findings should also be understood within the defined study population, intervention, comparator, and follow-up described in the registry record. The entry does not report details such as the dose or dosing schedule, and it does not supply efficacy estimates. No recommendation about treatment follows from these registry fields.

13. Why This Trial Matters Statistically

Statistically, this trial illustrates why an endpoint definition alone is not enough to evaluate efficacy. The registry record describes a clinically oriented caregiver-rated composite, the direction of its scale, the assessment time, and the use of LOCF. Those details help explain what a complete result would need to represent. But without group-level changes, a treatment contrast, and an uncertainty estimate, the endpoint cannot answer whether outcomes differed between randomized groups.

The record also makes the analysis population and missing-data method relevant to interpretation. The stated efficacy population requires post-baseline assessment information, and the primary analysis carries forward the last observation. In general, readers need to know how many participants contribute to each analysis and how missing observations are handled to judge the assumptions and possible selection effects. Those details are not fully reported in the registry record.

Multiple outcomes and assessment times create another statistical issue. In general, multiplicity planning helps clarify how evidence across several comparisons should be interpreted. The record lists primary and secondary outcomes but does not report a multiplicity strategy or the results. This leaves the inferential framework unclear.

The trial’s safety counts show why descriptive data should be distinguished from comparative inference. Event counts provide basic information, but without analysis and context they do not establish causation or quantify a treatment-related risk. Overall, the record is useful for identifying the design and measurement strategy, while its lack of posted analyses limits what can be concluded statistically.

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 efficacy is that the registry record does not report primary or secondary outcome results. It gives no group means, standard deviations, changes, treatment contrasts, confidence intervals, or p-values. No outcome analyses are listed. The effect and its precision therefore cannot be assessed from this record.

The primary endpoint relies on caregiver ratings, and the registry record does not describe rating procedures beyond identifying the parent/caregiver form. It does not report how ratings were collected or whether assessors were aware of group assignment. Although the trial is identified as double-masked, implementation details are not reported in the registry record.

The primary outcome uses LOCF, but the record does not provide missing-data counts, reasons for missingness, or sensitivity analyses. It also does not report the analysis count for the primary outcome. These omissions limit assessment of the assumptions and the extent to which the analyzed participants represent the randomized groups.

The registry record does not report the donepezil HCl dose or dosing schedule, the randomization procedures, a sample-size justification, a statistical analysis plan, or interim analyses. It also does not report a strategy for interpreting multiple outcomes and time points. These details should not be inferred from the trial title or design labels.

The safety information is limited to selected event counts and listed serious-event terms. The record does not give a comparative statistical analysis or fuller event-level context. These limitations constrain interpretation of both efficacy and safety; they do not establish that an unreported analysis was or was not conducted.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluating The Efficacy And Safety Of Donepezil Hydrochloride (HCl) (Aricept) In Treating Cognitive Dysfunction Exhibited By Children With Down Syndrome — NCT00570128.
• Registry record last updated 2021-04-19; status last verified 2021-03.
• Results first posted 2021-04-19.
• 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.

18. Record Summary

The registry record describes a completed, randomized, double-blind, parallel-group phase 2 trial comparing donepezil HCl with placebo in children and adolescents with Down syndrome. Enrollment is recorded as 129. The primary endpoint was change from baseline to Week 10 in the VABS-II/PCRF composite, analyzed using LOCF. Secondary outcomes included VABS-II/PCRF and TOVER measures at specified assessment times.

The record reports serious adverse events, other adverse events, and deaths by group, but lists no outcome analyses. Numerical efficacy results, uncertainty estimates, and a statistical analysis plan are not reported in the registry record. The available information therefore describes the study design and selected safety data, but does not establish the primary efficacy result.