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 Study Evaluating ACC-001 In Subjects With Mild To Moderate Alzheimer's Disease (NCT00498602), a randomized phase 2 study. The primary outcome is Percentage of Participants With Treatment-emergent AEs or Serious Adverse Events (SAEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00498602 |
| Phase | Phase 2 |
| Condition | Alzheimer Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 160 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
The trial enrolled subjects with mild to moderate Alzheimer’s disease. The safety population was defined as randomized participants with documented use of at least one dose of study drug. The registry record reports enrollment of 160, but the number in each treatment group varied in the posted safety breakdown.
Intervention
The study evaluated ACC-001 at different dose levels, both with and without QS-21. The listed safety groups include ACC 3 μg+QS-21, ACC 10 μg+QS-21, ACC 30 μg+QS-21, ACC 10 μg, and ACC 30 μg. The brief summary describes ACC-001 as an investigational active immunization.
Comparator
The posted safety breakdown also includes a QS-21 Alone group and a Phosphate Buffered Saline group. These groups provide context for reading adverse-event counts across the listed study regimens. The registry record does not report a single prespecified pairwise comparison as the main comparison for the safety endpoint.
Primary question
The primary endpoint asked what percentage of participants experienced treatment-emergent adverse events or serious adverse events. It was a safety and tolerability question, not a measure of clinical benefit. The registry describes treatment-emergent events as events that began during treatment or worsened compared with the pretreatment state.
The registry record identifies the trial as a Phase IIa study of safety, tolerability, and immunogenicity. It also lists antibody outcomes, including anti-A-beta IgG and IgM geometric mean titers, at multiple scheduled weeks. Those immune measurements are distinct from the primary safety question. The posted record does not report results for those antibody outcomes or a quantitative estimate comparing the safety of any regimen against another.
3. Trial Design
This was a randomized, parallel-group Phase IIa trial. The registry lists quadruple masking, while the official title describes the study as third-party unblinded. Those are the record’s descriptions; it does not explain how masking and third-party unblinding were implemented or reconciled. The trial is listed as completed.
The study evaluated ACC-001 at multiple dose levels, with and without the QS-21 adjuvant. The posted safety groups comprise five ACC-001 regimens, a QS-21 Alone group, and a Phosphate Buffered Saline group. The registry lists biological interventions for ACC-001 and QS-21, and lists the diluent as another intervention. Although the record labels the design randomized, it does not report the allocation ratio or describe the randomization procedure.
The planned observation period for the primary safety outcome was approximately 110 weeks, including a 6-week screening period, 52 weeks of dosing and 54 weeks for follow-up after the last dose. The trial start is recorded as 2007-11, and primary completion as 2013-02. The record does not give a detailed visit schedule for safety assessments beyond the endpoint timeframe.
Enrollment is listed as 160. The posted safety breakdown reports different numbers at risk across the groups, so enrollment should not be treated as the denominator for every group-level safety count. The record defines the safety population as randomized participants with documented use of at least one dose of study drug. It does not report how many randomized participants did not enter that population or why any participants may have been excluded.
The stated purpose was to assess safety, tolerability, and immunogenicity in subjects with mild to moderate Alzheimer’s disease. The registry record does not report the protocol’s rationale for choosing the dose levels, the planned sample-size justification, or a detailed statistical analysis plan.
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: The Basic Results disclose pooled data from studies NCT00479557 and NCT00498602.
Only the first 6 of 7 groups are shown.
Overall Study
| Stage | ACC 3 μg+QS-21 | ACC 10 μg+QS-21 | ACC 30 μg+QS-21 | ACC 10 μg | ACC 30 μg | QS-21 Alone |
|---|---|---|---|---|---|---|
| STARTED | 36 | 61 | 40 | 35 | 12 | 44 |
| Treated | 36 | 60 | 40 | 35 | 12 | 44 |
| COMPLETED | 26 | 51 | 32 | 30 | 8 | 31 |
| NOT COMPLETED | 10 | 10 | 8 | 5 | 4 | 13 |
Reasons for not completing this period:
| Reason | ACC 3 μg+QS-21 | ACC 10 μg+QS-21 | ACC 30 μg+QS-21 | ACC 10 μg | ACC 30 μg | QS-21 Alone |
|---|---|---|---|---|---|---|
| Death | 0 | 0 | 0 | 0 | 0 | 1 |
| Lack of Efficacy | 1 | 0 | 0 | 0 | 0 | 0 |
| Lost to Follow-up | 0 | 2 | 0 | 2 | 0 | 0 |
| Adverse Event (AE) related to Study Drug | 1 | 0 | 3 | 2 | 0 | 1 |
| AE not related to Study Drug | 1 | 3 | 0 | 0 | 2 | 2 |
| Caregiver Request | 2 | 2 | 2 | 0 | 1 | 2 |
| Investigator Request | 0 | 0 | 1 | 0 | 0 | 0 |
| Subject Request | 3 | 0 | 1 | 1 | 1 | 4 |
| Other | 2 | 3 | 1 | 0 | 0 | 3 |
Analysis population for the primary outcome, as defined in the registry: The safety population included all randomized participants with documented use of at least one dose of study drug.
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.
Population: 245 participants were randomized in both studies (86 participants in NCT00479557 and 159 participants in NCT00498602) are included in the analysis below. One participant of the randomized participants did not receive treatment.
Only the first 6 of 8 groups are shown.
| Characteristic | Unit | ACC 3 μg+QS-21 | ACC 10 μg+QS-21 | ACC 30 μg+QS-21 | ACC 10 μg | ACC 30 μg | QS-21 Alone |
|---|---|---|---|---|---|---|---|
| Participants analysed | 36 | 61 | 40 | 35 | 12 | 44 | |
| Age, Continuous | Years | 65.7 (SD 7.75) | 69.3 (SD 9.57) | 69.0 (SD 9.27) | 71.9 (SD 8.96) | 70.9 (SD 9.59) | 68.8 (SD 8.07) |
| Sex: Female, Male: Female | Participants | 16 | 29 | 22 | 19 | 8 | 31 |
| Sex: Female, Male: Male | Participants | 20 | 32 | 18 | 16 | 4 | 13 |
| Race/Ethnicity, Customized: Asian | number of participants | 0 | 0 | 0 | 0 | 1 | 0 |
| Race/Ethnicity, Customized: Black or African American | number of participants | 1 | 0 | 1 | 0 | 0 | 1 |
| Race/Ethnicity, Customized: Other | number of participants | 2 | 1 | 1 | 1 | 0 | 0 |
| Race/Ethnicity, Customized: White | number of participants | 33 | 60 | 38 | 34 | 11 | 43 |
| Mini-Mental State Examination (MMSE) Score | score | 21.4 (SD 2.96) | 21.4 (SD 3.38) | 21.0 (SD 2.92) | 21.6 (SD 3.16) | 21.8 (SD 3.60) | 21.7 (SD 3.11) |
| MMSE Stratum: High (21 - 26) | number of participants | 26 | 40 | 24 | 23 | 8 | 29 |
| MMSE Stratum: Low (16 - 20) | number of participants | 10 | 21 | 16 | 12 | 4 | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Treatment-emergent AEs or Serious Adverse Events (SAEs), measured over approximately 110 weeks, including a 6-week screening period, 52 weeks of dosing and 54 weeks for follow-up after the last dose.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint was the percentage of participants with treatment-emergent adverse events or serious adverse events. An adverse event was defined broadly as an untoward, undesired, or unplanned clinical event, including signs, symptoms, disease, or laboratory or physiologic observations. The event did not have to be judged causally related to study drug or study participation. A treatment-emergent event was one that appeared during treatment after being absent before treatment, or worsened during treatment compared with the pretreatment state.
The registry defines serious adverse events by outcomes or significance, including death, initial or prolonged inpatient hospitalization, an immediately life-threatening experience, persistent or significant disability or incapacity, and congenital anomaly. This classification reflects seriousness, not necessarily whether the event was caused by treatment.
Safety endpoints are used to describe the kinds and frequency of unwanted events observed during study participation. They are relevant to tolerability because they capture events over the treatment and follow-up period, including events without an established causal relationship. The endpoint does not, by itself, show whether a regimen caused an event or whether the observed event frequency differs reliably between regimens.
The registry record gives the endpoint definition and timeframe but does not report an overall endpoint percentage or a statistical comparison for it. The group-level counts posted separately should therefore be read as safety descriptions, not as a complete inferential analysis of the primary endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies safety as the primary outcome, but it does not post an overall percentage for participants with treatment-emergent adverse events or serious adverse events, confidence intervals, or a statistical comparison. The available group breakdown gives counts of participants at risk and counts affected for serious events and for other adverse events. These counts describe what was recorded in each group; without an accompanying analysis, they do not establish whether differences between groups are larger than would be expected from sampling variability.
For serious adverse events, the reported affected counts range across the listed groups, with denominators that also vary. For the other adverse-event category, affected counts are posted for each group. These are group-specific descriptions, not direct evidence that one regimen has a higher or lower risk than another. A comparison would need to define the measure being compared, account for the relevant denominators and analysis population, and report uncertainty. Those details are not reported in the registry record.
The serious-event term list reports six terms, each with a percentage of 8.3%. The record does not provide enough context in this listing to establish whether those terms are mutually exclusive, how repeated events were handled, or what denominator was used for the term percentages. The percentages should therefore be treated as the registry’s reported term values rather than converted into participant counts or compared across terms.
Some participants may have experienced more than one type of event. The serious-event count and the other-event count cannot be added to obtain a total number of affected participants because the record does not state that the categories are mutually exclusive. Likewise, the group counts should not be combined to create an overall estimate without knowing the intended pooling method and whether participants can appear in more than one listed treatment group.
The record lists secondary immunogenicity outcomes based on anti-A-beta IgG and IgM geometric mean titers, as well as IgG subtypes. These outcomes are scheduled at multiple visits, but no results are posted in the available record. Thus the registry information does not support conclusions about the pattern or magnitude of antibody responses.
The posted material is descriptive rather than a reported comparative analysis. The registry record does not report effect estimates, confidence intervals, p-values, adjusted analyses, or a statistical analysis plan for the safety outcome. Without those, the precision of any between-group difference cannot be assessed. The absence of posted inferential results also does not mean that no such analyses were performed outside the registry record.
The distinction between adverse events and treatment-caused harms is important. The registry’s definition explicitly includes events without a causal relationship to study drug. Counts therefore describe events observed during the study, not necessarily events caused by ACC-001, QS-21, or the diluent. Interpretation should stay within that scope.
9. Statistical Methods Explained
What does a group count describe?
A count of participants with an event is a direct description of how many participants in a group were recorded as affected. The corresponding number at risk identifies the group denominator used for that safety listing. Counts alone are not a comparison of risks: groups can differ in size, and an absolute count does not account for that difference. The registry record posts both affected counts and denominators for the adverse-event categories, but it does not report a formal comparison of those group-level results.
For a percentage endpoint, the usual descriptive quantity is the number of participants meeting the event definition relative to the number included in the relevant population. A reported percentage should be interpreted alongside its denominator and the population definition. Here, the primary endpoint is described as a percentage, but its overall numerical result is not reported in the registry record. The group-level adverse-event breakdown is not a substitute for an overall primary-endpoint estimate.
Why does uncertainty matter?
General statistical explanation: an estimate from a clinical trial is subject to sampling variability because the enrolled participants are only one realization of the population that could have entered the study. A confidence interval expresses a range of values compatible with the data under the analysis method. Narrower intervals generally indicate greater precision, while wider intervals indicate less precision. The registry record does not report confidence intervals for the primary safety outcome or for group comparisons, so the precision of any difference cannot be evaluated from the posted results.
A test of statistical significance addresses a different question from the size or clinical importance of an estimated difference. A p-value, when reported, summarizes how compatible the observed data are with a specified null model under assumptions of the analysis. It does not measure the probability that a treatment caused an event, nor does a non-significant result establish equivalence. No p-values for the primary outcome are reported in the registry record.
How should multiple groups be considered?
There are several ACC-001 dose groups, with and without QS-21, as well as QS-21 Alone and Phosphate Buffered Saline groups. General statistical explanation: evaluating many groups or many pairwise comparisons can increase the chance of finding an apparently unusual result simply through repeated testing. A prespecified comparison plan and a multiplicity approach can help define how those comparisons should be interpreted. The registry record does not report a multiplicity plan, a primary pairwise contrast, or adjusted comparison results. It is therefore not appropriate to select one group contrast after seeing the descriptive counts and treat it as a prespecified confirmatory finding.
Differences between groups could also reflect variation in group size and chance. General statistical explanation: random allocation is intended to make treatment groups comparable in expectation, but it does not guarantee that observed groups will be identical on every characteristic. The registry record identifies the trial as randomized but does not provide baseline characteristics or a detailed account of allocation methods in the information posted for these results. No adjustment for baseline factors is reported.
What does an event category mean?
The endpoint includes treatment-emergent adverse events and serious adverse events. The registry’s definitions allow events that are not causally related to study drug to be included. This broad capture is useful for describing safety observations, but it means that event counts should not be read as counts of proven treatment-caused harms. Seriousness is classified by specified outcomes or clinical significance; it is not the same concept as severity or causality.
The serious and other adverse-event counts may overlap at the participant level. A participant could potentially have more than one event, or an event could have more than one relevant classification. Since the record does not describe event-level deduplication or overlap across these categories, the counts should not be summed to make a participant total. General statistical explanation: analyses of event counts also need to distinguish the number of participants affected from the number of events, since multiple events in one participant can produce different totals.
What can be said about the analysis population?
The stated safety population includes randomized participants with documented use of at least one dose of study drug. This is a post-randomization population definition: it focuses on participants who actually began study treatment, rather than every randomized participant. General statistical explanation: the analysis population affects the question an estimate answers. A treated safety population is commonly used to describe events after exposure, while an analysis of all randomized participants would retain the original randomized groups and address a different analysis target. The record does not report the number randomized in each group, the number excluded from the safety population, or a separate analysis of all randomized participants.
The record also does not describe methods for handling missing safety observations, withdrawals, or incomplete follow-up. That information is important because participants with incomplete observation may have less opportunity for events to be recorded. No assumptions or sensitivity analyses for missing data are reported in the registry record.
What is not available for interpretation?
No inferential outcome analyses are posted in the record. It does not report a statistical model, covariate adjustment, confidence intervals, p-values, or a prespecified method for comparing the treatment groups. It also does not report a sample-size justification or interim-analysis plan. These omissions limit what can be inferred from the descriptive counts; they should not be filled in by assuming standard methods were used. The registry record’s stated endpoint, group counts, and event definitions are the appropriate basis for a cautious descriptive reading.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several dose and adjuvant groups, a primary safety endpoint, and secondary antibody outcomes measured at multiple scheduled weeks. This creates the possibility of multiple comparisons across treatment regimens, outcomes, and time points. General statistical explanation: when many hypotheses are tested, the chance of at least one apparently notable result can rise unless the comparison strategy is specified and accounted for. The registry record does not report a multiplicity adjustment, a hierarchy of outcomes, or a prespecified set of primary contrasts.
The record does not post outcome analyses for the primary safety endpoint or the secondary immunogenicity measures. It therefore contains no reported p-values, confidence intervals, or adjusted results to interpret. The record also does not describe how missing data or incomplete follow-up were handled, whether participants who discontinued remained in any analysis, or whether sensitivity analyses were performed. Each of these details is not reported in the registry record.
The safety population is defined as randomized participants with documented use of at least one dose of study drug. The registry record does not provide a full disposition accounting showing how many randomized participants entered that population in each group, or how missing follow-up affected the safety summaries. Because the definition conditions inclusion on documented exposure, it differs from an analysis that includes every randomized participant.
Although the study is identified as randomized and quadruple masked, the record does not report a detailed statistical analysis plan, sample-size justification, interim analyses, or the procedures used to preserve masking while allowing third-party unblinding as described in the official title. These items should not be inferred from the design labels. The posted safety counts remain descriptive in the absence of reported analysis methods and uncertainty estimates.
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 |
|---|---|---|---|
| ACC 3 μg+QS-21 | 6 | 36 | 16.7% |
| ACC 10 μg+QS-21 | 11 | 60 | 18.3% |
| ACC 30 μg+QS-21 | 7 | 40 | 17.5% |
| ACC 10 μg | 5 | 35 | 14.3% |
| ACC 30 μg | 5 | 12 | 41.7% |
| QS-21 Alone | 5 | 44 | 11.4% |
| Phosphate Buffered Saline | 3 | 17 | 17.6% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| ACC 3 μg+QS-21 | 34 of 36 |
| ACC 10 μg+QS-21 | 48 of 60 |
| ACC 30 μg+QS-21 | 35 of 40 |
| ACC 10 μg | 28 of 35 |
| ACC 30 μg | 10 of 12 |
| QS-21 Alone | 40 of 44 |
Most frequent serious adverse event terms
| Event term | Organ system | ACC 3 μg+QS-21 | ACC 10 μg+QS-21 | ACC 30 μg+QS-21 | ACC 10 μg | ACC 30 μg | QS-21 Alone |
|---|---|---|---|---|---|---|---|
| Dizziness | Nervous system disorders | 1 of 36 | 1 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 0 of 44 |
| Syncope | Nervous system disorders | 1 of 36 | 0 of 60 | 1 of 40 | 0 of 35 | 0 of 12 | 0 of 44 |
| Vasogenic cerebral oedema | Nervous system disorders | 0 of 36 | 0 of 60 | 1 of 40 | 1 of 35 | 0 of 12 | 0 of 44 |
| Myocardial infarction | Cardiac disorders | 1 of 36 | 1 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 0 of 44 |
| Gastroenteritis | Infections and infestations | 1 of 36 | 0 of 60 | 1 of 40 | 0 of 35 | 0 of 12 | 0 of 44 |
| Renal failure acute | Renal and urinary disorders | 0 of 36 | 1 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 1 of 44 |
| Vertigo positional | Ear and labyrinth disorders | 0 of 36 | 2 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 0 of 44 |
| Ataxia | Nervous system disorders | 0 of 36 | 0 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 1 of 44 |
| Balance disorder | Nervous system disorders | 0 of 36 | 0 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 1 of 44 |
| Bradykinesia | Nervous system disorders | 0 of 36 | 0 of 60 | 0 of 40 | 0 of 35 | 0 of 12 | 1 of 44 |
Most frequent non-serious adverse event terms
| Event term | Organ system | ACC 3 μg+QS-21 | ACC 10 μg+QS-21 | ACC 30 μg+QS-21 | ACC 10 μg | ACC 30 μg | QS-21 Alone |
|---|---|---|---|---|---|---|---|
| Injection site pain | General disorders | 7 of 36 | 17 of 60 | 9 of 40 | 4 of 35 | 1 of 12 | 6 of 44 |
| Headache | Nervous system disorders | 3 of 36 | 14 of 60 | 4 of 40 | 2 of 35 | 0 of 12 | 8 of 44 |
| Depression | Psychiatric disorders | 5 of 36 | 4 of 60 | 4 of 40 | 8 of 35 | 3 of 12 | 5 of 44 |
| Diarrhoea | Gastrointestinal disorders | 10 of 36 | 6 of 60 | 4 of 40 | 4 of 35 | 2 of 12 | 3 of 44 |
| Injection site erythema | General disorders | 7 of 36 | 9 of 60 | 6 of 40 | 0 of 35 | 0 of 12 | 1 of 44 |
| Fall | Injury, poisoning and procedural complications | 3 of 36 | 3 of 60 | 3 of 40 | 4 of 35 | 1 of 12 | 9 of 44 |
| Fatigue | General disorders | 5 of 36 | 7 of 60 | 4 of 40 | 1 of 35 | 0 of 12 | 5 of 44 |
| Nausea | Gastrointestinal disorders | 5 of 36 | 9 of 60 | 1 of 40 | 2 of 35 | 0 of 12 | 5 of 44 |
| Cough | Respiratory, thoracic and mediastinal disorders | 6 of 36 | 4 of 60 | 2 of 40 | 2 of 35 | 2 of 12 | 4 of 44 |
| Agitation | Psychiatric disorders | 4 of 36 | 4 of 60 | 0 of 40 | 5 of 35 | 2 of 12 | 4 of 44 |
Serious events with the highest arm-level rate: cerebrovascular accident (8.3%), lung neoplasm malignant (8.3%), decreased appetite (8.3%), agitation (8.3%), confusional state (8.3%).
For serious adverse events, the posted counts and numbers at risk are: ACC 3 μg+QS-21, 6 of 36; ACC 10 μg+QS-21, 11 of 60; ACC 30 μg+QS-21, 7 of 40; ACC 10 μg, 5 of 35; ACC 30 μg, 5 of 12; QS-21 Alone, 5 of 44; and Phosphate Buffered Saline, 3 of 17. For other adverse events, the respective affected counts and numbers at risk are 34 of 36, 48 of 60, 35 of 40, 28 of 35, 10 of 12, 40 of 44, and 17 of 17.
These are separate descriptive categories. The registry record does not state that they are mutually exclusive, so their counts should not be added to estimate the number of unique participants affected. The serious-event term listing reports Cerebrovascular accident, Lung neoplasm malignant, Decreased appetite, Agitation, Confusional state, and Hallucination, each at 8.3%. The record does not provide enough detail in that listing to establish the denominator or whether a participant could contribute to multiple terms.
Deaths are not reported in the registry record. The posted counts do not establish causality, and no uncertainty estimates or statistical comparisons are reported.
12. What the Result Does, and Does Not, Mean
The registry record describes a randomized study of ACC-001 regimens, with or without QS-21, in subjects with mild to moderate Alzheimer’s disease. Its primary question concerned treatment-emergent adverse events and serious adverse events over an approximately 110-week observation period. The group-level safety data give affected counts and numbers at risk, and the serious-event term list gives several reported percentages.
These data do not establish that an event was caused by a study treatment. The endpoint definition includes adverse events regardless of causal relationship, and the registry does not post a causal assessment for the listed events. Nor do the descriptive counts establish that one regimen has more or fewer events than another in a statistically reliable way. No primary-endpoint estimate, confidence interval, p-value, or comparative analysis is reported.
The record also does not report results for the listed immunogenicity outcomes. Although anti-A-beta IgG, anti-A-beta IgM, and IgG subtype measurements appear among the secondary outcomes, there are no posted values from which to describe antibody responses or compare regimens.
Interpretation is further limited by the absence of reported information on missing-data handling, group-level participant disposition, multiplicity procedures, and the statistical analysis plan. The safety population includes randomized participants with documented use of at least one dose, but the record does not provide a full account of how this population relates to all randomized participants in each group.
Accordingly, the registry record supports a descriptive reading of the posted safety counts and endpoint definitions. It does not support conclusions about treatment efficacy, comparative safety, the precision of treatment differences, or the cause of individual events. It also does not establish that no additional analyses were conducted outside the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable for the range of dose and adjuvant regimens represented in the safety breakdown. Multiple groups can make descriptive patterns useful to inspect, but they also make a prespecified comparison strategy important. Without a reported primary contrast or multiplicity plan, readers cannot determine which group differences, if any, were intended to carry confirmatory weight.
The endpoint also illustrates why event definitions and analysis populations matter. The primary outcome concerns treatment-emergent events, while the safety population includes randomized participants with documented exposure. Events are included even without a causal relationship to study drug. These choices define what the endpoint describes and prevent a direct interpretation as a count of proven treatment-caused harms.
The record provides group-specific counts and denominators, but no inferential analyses or uncertainty estimates. This distinction is central in clinical research: observed counts are evidence about what happened among participants in the study, whereas comparison and precision require an explicit analysis framework. The registry’s lack of reported analyses means readers should not turn descriptive differences into conclusions about comparative safety.
Finally, the study lists immunogenicity outcomes at multiple scheduled visits but does not post their results. This underscores the difference between an outcome named in a registry and an outcome with interpretable results available. For clinical researchers, transparent reporting of outcome values, denominators, missing-data handling, and analysis methods is necessary to assess how strongly any observed pattern supports a conclusion.
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 registry record does not report a numerical result for the primary endpoint as defined: the percentage of participants with treatment-emergent adverse events or serious adverse events. Instead, it provides group-level counts for serious events and other adverse events. It does not explain whether these categories overlap, how repeated events were treated, or how the counts relate to the primary endpoint’s combined wording.
Group sizes in the safety breakdown vary, and the record does not provide a full participant disposition account by randomized group. Enrollment is 160, while the posted numbers at risk for the listed safety groups are not a single common denominator. The relationship between enrollment, randomized participants, and the safety population is not fully described in the registry record.
The listed serious-event terms each have a reported percentage, but the record does not give the denominator or clarify whether the percentages refer to participants or events. It also does not describe whether a person could be counted under multiple terms. Death counts are not reported in the registry record.
No confidence intervals, p-values, comparative estimates, or adjustment procedures are posted. The record does not report how missing observations, withdrawals, or incomplete follow-up were handled. Results for the antibody outcomes are also not reported, despite their listing as secondary outcomes at multiple weeks.
The record identifies randomization and quadruple masking, while the official title describes third-party unblinding. It does not provide procedural detail explaining these design labels. The allocation ratio, sample-size justification, interim-analysis plan, and detailed statistical analysis plan are not reported in the registry record. These gaps limit interpretation but should not be used to infer that particular methods were or were not applied outside the registry.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study Evaluating ACC-001 In Subjects With Mild To Moderate Alzheimer's Disease — NCT00498602.
- Registry record last updated 2016-01-01; status last verified 2015-11.
- Results first posted 2016-01-01.
- 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
This completed Phase IIa randomized parallel-group study evaluated ACC-001, with and without QS-21, in subjects with mild to moderate Alzheimer’s disease. Enrollment was 160. The primary endpoint was the percentage of participants with treatment-emergent adverse events or serious adverse events over approximately 110 weeks, including screening, dosing, and follow-up.
The registry posts group-level affected counts and numbers at risk for serious and other adverse events, along with a list of serious-event terms. It does not report an overall primary-endpoint percentage, comparative statistical analyses, or results for the listed immunogenicity outcomes. Details on missing data, multiplicity, and the statistical analysis plan are not reported in the registry record.