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 Long-Term One Year Use of Alefacept (Amevive®) in Moderate to Severe Chronic Plaque Type Psoriasis (NCT00655564), a na phase 4 study. The primary outcome is Efficacy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00655564 |
| Phase | Phase 4 |
| Condition | Psoriasis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Wake Forest University |
| Results posted | Yes |
2. Clinical Question
Population
People with moderate to severe chronic plaque psoriasis. The record lists psoriasis as the condition and describes the study in that disease context; detailed participant eligibility criteria are not reported in the registry record.
Intervention
Alefacept, studied as continuous treatment over a 52-week outcome period. The specific continuous dosing schedule used in the study is not reported in the registry record.
Comparator
No comparator group is listed. The study is recorded as a single-group study, with allocation marked not applicable and no masking.
Primary question
How many participants had a 75% reduction in Psoriasis Area and Severity Index score from baseline to week 52 during continuous alefacept use?
The clinical question is descriptive rather than a controlled comparison. The primary outcome counts participants who meet a specified PASI response threshold by the end of the stated follow-up period. It does not, by itself, estimate how outcomes would differ under another treatment or under no treatment.
The registry describes the study purpose as examining continuous alefacept treatment. It also notes that the FDA-approved schedule described in the record is intermittent, but that context does not establish the exact regimen participants followed in this study. The study-specific dosing details are not reported in the registry record.
The enrolled population is recorded as 15 participants. Further details about the characteristics of those participants, including how closely they matched the stated disease severity, are not reported in the registry record. The available record therefore defines the question and endpoint, but does not give enough information to assess the observed efficacy response or compare it with an alternative.
3. Trial Design
This is a completed phase 4 study sponsored by Wake Forest University. The registry lists a start date of 2008-05 and a primary completion date of 2009-12. Enrollment is recorded as 15 participants, and psoriasis is the listed condition.
The design is identified as single group. Allocation is marked not applicable, and masking is listed as none. Alefacept is the intervention. There is no separate control arm in the registry record, so the design does not support a randomized or blinded comparison between treatments. A comparator or placebo is not reported in the registry record.
The primary outcome is described as the number of participants with a 75% reduction in PASI score from baseline to week 52. The record lists safety of alefacept using CD4 counts as a secondary outcome. It records 2 outcome measures and 0 analyses. No efficacy result, statistical comparison, or analysis estimate is reported in the registry record.
The study purpose refers to continuous treatment, while the record also gives an FDA-approved intermittent schedule as background. The actual study dosing schedule, adherence procedures, and any permitted changes to treatment are not reported in the registry record. Thus, the design can be characterized as a small, single-group study with a defined endpoint and follow-up time, but its operational details cannot be reconstructed from the available information.
Because there is no concurrent control group, changes between baseline and week 52 would be observed within participants rather than contrasted with outcomes under another treatment. Even if the responder count were available, that count alone would not separate treatment effects from other explanations for change over time.
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 | Alefacept |
|---|---|
| STARTED | 15 |
| COMPLETED | 12 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Alefacept |
|---|---|
| Adverse Event | 1 |
| Lost to Follow-up | 1 |
| Desired Alternate Therapy | 1 |
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 | Alefacept |
|---|---|---|
| Participants analysed | 15 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 15 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 12 |
| Region of Enrollment: United States | participants | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Efficacy, measured over 52 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | #Participants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of participants whose PASI score is reduced by 75% or more from baseline to week 52. PASI is a measure of psoriasis area and severity; the endpoint converts change in that score into a responder count using a threshold. The registry labels the unit as participants and the timeframe as 52 weeks.
A responder endpoint can make a continuous score easier to interpret by distinguishing participants who meet a prespecified level of improvement from those who do not. It also gives a count that can be described directly. However, converting a score change into a thresholded outcome loses information: participants just on opposite sides of the cutoff are classified differently, while participants with substantially different changes can be grouped together if they remain on the same side of it. This is a general feature of threshold-based outcomes.
The endpoint definition does not disclose the observed responder count. That result, the baseline and week-52 score summaries, and any uncertainty estimate are not reported in the registry record. It is therefore not possible to describe the size or precision of the observed efficacy response from this record. The endpoint states what was intended to be counted, not what the study found.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry defines an efficacy outcome but does not post its result. It specifies a count of participants meeting a 75% PASI reduction threshold from baseline to week 52. No observed count, estimate of response, confidence interval, or test result is reported in the registry record. Consequently, the posted information does not quantify the efficacy outcome or its precision.
The record lists 15 participants enrolled. Enrollment alone does not establish how many participants contributed data to the week-52 endpoint. The number assessed at that time, the number excluded from the endpoint analysis, and reasons for any missing assessments are not reported in the registry record. Without those details, the analysis denominator and the handling of incomplete follow-up cannot be evaluated.
The design is single group, with no comparator listed. Any within-participant change from baseline, if reported, would describe change over time in this group. It would not establish how the same participants would have fared under another treatment or without alefacept. This is a general limitation of uncontrolled studies: changes may reflect treatment, the natural course of disease, other care, participant selection, or measurement and follow-up processes.
The record lists 0 analyses. It therefore does not provide an inferential analysis for the primary efficacy endpoint. No adjustment variables, uncertainty estimates, or analysis populations are described. The absence of a posted analysis is not evidence that the endpoint had no effect; it means the registry record does not report an estimate on which to base that interpretation.
Safety information is listed separately. The Alefacept group has 15 participants at risk for serious adverse events and 2 affected, while 15 are at risk for other adverse events and 8 are affected. Two serious adverse-event terms are listed, each with 6.7%. These counts describe reported safety observations in this group; they do not provide a controlled estimate of excess risk or establish that alefacept caused an event.
Overall, the record establishes the study question, design, endpoint definition, enrollment, and selected safety counts. It does not report the primary efficacy result or enough methodological detail to assess its uncertainty, completeness, or susceptibility to bias. Interpretation should remain limited to those details.
9. Statistical Methods Explained
Statistical methods determine how outcomes are defined, which participants contribute data, how estimates are calculated, and how uncertainty is expressed. The registry record identifies the primary endpoint and study design, but does not describe a statistical analysis plan. General explanations below clarify the methods that would ordinarily matter for interpreting this type of study; they should not be read as claims about methods actually used.
What does a single-group design estimate?
A single-group study observes outcomes in participants receiving the intervention without a concurrent comparison group. For a responder endpoint, the basic descriptive quantity is the number of participants who meet the response definition among those assessed. A proportion could also be reported, but the registry does not give the observed responder count or analysis denominator, so no such result can be stated.
Without a control group, a before-and-after difference is not a treatment contrast. General explanations for observed change can include the intervention, the course of the condition, other care, selection into the study, or changes in how outcomes are measured. Random allocation to comparison groups is one way trials aim to balance such influences, but this record lists a single group and no allocation.
What does the responder threshold mean?
The primary outcome classifies participants according to whether their PASI score has a 75% reduction from baseline by week 52. This creates an interpretable responder category, but it compresses the underlying score information. A threshold can be useful when the question concerns reaching a defined level of improvement, while still obscuring the amount of change among responders and nonresponders. The registry does not report the score distributions or the number meeting the threshold.
Clear endpoint definitions also need operational detail: how baseline was selected, how a score was collected, whether assessment procedures were standardized, and how missing week-52 scores were handled. These details are not reported in the registry record. The definition names the comparison time points and threshold, but does not resolve those implementation questions.
How should uncertainty be understood?
A confidence interval is a general statistical tool for expressing uncertainty around an estimate. For a responder outcome, an interval around a response proportion would reflect the limited information in the observed sample as well as the variability expected under the statistical model. An interval is not a guarantee about an individual outcome, and its interpretation depends on the data and method used.
No confidence interval, standard error, or other uncertainty measure for the primary outcome is reported in the registry record. The sample enrollment of 15 does not substitute for an uncertainty estimate. Because the endpoint result and its denominator are also absent, the precision of the efficacy estimate cannot be assessed.
What can a statistical test establish?
A statistical test evaluates data against a defined null hypothesis under specified assumptions. A p-value, if reported, would describe how incompatible the observed data are with that null model; it would not measure the magnitude or clinical importance of an effect. The record lists 0 analyses and contains no p-value or stated hypothesis test for the primary endpoint. The test method, if any was used outside the registry entry, is not reported in the registry record.
Sample-size planning is distinct from a trial result. Planning illustrations can show how a hypothetical design might perform under selected assumptions, but they are not observed power and do not establish what the study found. The planning assumptions associated with illustrations include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a stated fraction of the observed effect. Those are illustration assumptions, not a reported protocol or analysis plan for this single-group study. No sample-size justification for the study is reported in the registry record.
In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. If present, it can make standard errors and confidence intervals too small when the model does not account for it. The registry identifies the outcome as a participant count and gives no dispersion parameter or model-based analysis. There is no basis in the record for saying over-dispersion was assessed or that it affected the results.
Which analysis population matters?
Trial reports commonly distinguish participants enrolled, participants who began treatment, and participants with outcome data, and may define which group is used for each analysis. Those distinctions matter because exclusions or missing assessments can change the denominator and potentially the interpretation. Here, enrollment is 15, but analysis populations and the number with week-52 endpoint data are not reported in the registry record. No intention-to-treat, per-protocol, or other analysis population is identified.
The registry also lists safety of alefacept using CD4 counts as a secondary outcome. It does not give a statistical method, summary result, or analysis population for that outcome. The same caution applies to all statistical interpretation: endpoint definitions and design information are available, but the methods and efficacy analysis needed to quantify results are not.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when a study evaluates multiple outcomes, time points, subgroups, or statistical tests. If many hypotheses are tested, the chance of at least one apparently notable result can increase unless the analysis plan addresses that issue. This is a general statistical concern, not evidence that a particular adjustment was required or performed in this study.
The record lists a primary efficacy outcome and a secondary outcome concerning safety using CD4 counts. It reports 2 outcome measures and 0 analyses. A multiplicity strategy, hierarchy among outcomes, or adjustment for multiple testing is not reported in the registry record. The available information therefore does not show whether multiplicity was considered in the study analysis.
Missing data are also important for the week-52 endpoint. The record does not report the number of participants with a week-52 PASI assessment, reasons for missing assessments, or a method for handling missing outcomes. It does not identify analysis populations or state whether all enrolled participants were included in efficacy or safety analyses. Enrollment of 15 cannot be treated as proof that all 15 contributed endpoint data.
These omissions limit assessment of potential bias and precision. If outcome availability differs across participants, the observed results can depend on how missingness is handled. Without the data-flow information or analysis plan, the direction and magnitude of any such influence cannot be judged. The registry record also does not report interim analyses, stopping rules, or a prespecified statistical analysis plan.
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 |
|---|---|---|---|
| Alefacept | 2 | 15 | 13.3% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Alefacept | 8 of 15 |
Most frequent serious adverse event terms
| Event term | Organ system | Alefacept |
|---|---|---|
| Low CD4 cell count | Immune system disorders | 1 of 15 |
| Severe allergic contact dermatitis | Skin and subcutaneous tissue disorders | 1 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Alefacept |
|---|---|---|
| Upper respiratory infection | Respiratory, thoracic and mediastinal disorders | 4 of 15 |
| Back pain | Musculoskeletal and connective tissue disorders | 2 of 15 |
| Generalized muscle aches | Musculoskeletal and connective tissue disorders | 1 of 15 |
| Breast tenderness | Reproductive system and breast disorders | 1 of 15 |
| Eye irritation | Eye disorders | 1 of 15 |
| Generalized itching | Skin and subcutaneous tissue disorders | 1 of 15 |
Serious events with the highest arm-level rate: low cd4 cell count (6.7%), severe allergic contact dermatitis (6.7%).
For the Alefacept group, the registry reports 15 participants at risk for serious adverse events and 2 affected. For other adverse events, it reports 15 at risk and 8 affected. These are participant-level counts as represented in the registry outcome fields; they should not be interpreted as a count of every event episode unless the record specifies that meaning.
The serious adverse-event terms listed are low CD4 cell count and severe allergic contact dermatitis, each reported as 6.7%. The record does not explain whether participants could contribute to more than one term or how the term percentages were calculated. Those details are not reported in the registry record.
The counts describe events recorded in this group, not a causal effect. With no comparison group, the figures cannot show whether the occurrence was more or less common than it would have been under another treatment or without alefacept. The registry does not report deaths; the death value is not reported in the registry record. Definitions, follow-up procedures, and attribution assessments are also not reported, so the counts should be read as limited descriptive safety information.
12. What the Result Does, and Does Not, Mean
The record establishes that a phase 4, single-group study of alefacept was completed, enrolled 15 participants, and defined a week-52 PASI responder outcome. It also lists safety information for the Alefacept group. These details help identify the study question and the kinds of outcomes recorded.
The record does not report the primary efficacy count or an efficacy analysis. It therefore does not establish how many participants met the PASI response definition, how variable the outcome was, or how precise an estimate might be. No conclusion about the magnitude of an efficacy response can be drawn from the endpoint definition alone.
Even if a responder count were available, the single-group design would describe outcomes among participants in the study rather than a comparative treatment effect. Without a control group, it would not separate changes associated with alefacept from other influences. This is a design limitation, not a judgment about the direction of the observed outcome.
The safety counts indicate that serious and other adverse events were recorded among participants at risk, and the record names two serious adverse-event terms. They do not establish causation or allow comparison with another treatment. The details needed to understand event definitions, follow-up completeness, and attribution are not reported in the registry record.
Accordingly, the most defensible reading is descriptive and limited: the registry documents a study design, endpoint definition, enrollment, and selected safety counts, while leaving the primary efficacy result and key analysis details unreported. The record cannot answer how outcomes would compare with an alternative regimen or a control condition.
13. Why This Trial Matters Statistically
This study is statistically notable because its primary question is stated in a concrete responder format while its posted record lacks the outcome result. The endpoint specifies a thresholded PASI change from baseline to week 52. That definition clarifies what the study intended to count, but the absence of the count and analysis prevents readers from evaluating the observed response or its uncertainty.
The single-group design also illustrates the distinction between describing change and estimating a comparative effect. Within-group outcomes can be useful for documenting what occurred among participants, but without a concurrent comparator they do not isolate the intervention's contribution. The registry's design labels make that interpretive boundary explicit.
Enrollment of 15 highlights why complete reporting of denominators, missing assessments, and uncertainty is important. A reader needs to know who contributed data to the endpoint and how the analysis treated incomplete follow-up. Those details are not reported in the registry record, so enrollment cannot stand in for an analyzed sample.
The safety entries show another important distinction: event counts and percentages are descriptive observations, not causal estimates. A controlled comparison and clear event definitions would be needed to interpret relative safety, while this record lists no comparator and provides limited event detail.
More broadly, the record demonstrates that an endpoint description, a completed status, and enrollment information do not amount to a complete statistical result. Reporting the outcome estimate, its denominator, uncertainty, and analysis methods would be necessary for a fuller assessment. The registry information is useful for defining what was studied, but leaves those central statistical questions unresolved.
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 most direct limitation is that the registry does not report the primary efficacy result. Although the endpoint is defined as the number of participants with a 75% PASI reduction by week 52, the observed number and analysis denominator are absent. No confidence interval, test result, or other estimate is reported.
The study has no listed comparator and is identified as single group, with allocation not applicable and masking none. This prevents a controlled estimate of differences between alefacept and another treatment. Any observed change, if reported elsewhere, would remain vulnerable to explanations that a comparator group could help address.
The enrolled sample is 15, but the number with endpoint data is not reported. The registry does not describe missing data, participant disposition, analysis populations, or exclusions. It also does not give detailed eligibility criteria, baseline characteristics, or the actual continuous dosing schedule used. These omissions limit assessment of who was studied, what treatment exposure occurred, and how representative the participants may be.
The record lists safety counts and serious-event terms but does not report event definitions, attribution, timing, or whether term categories overlap. Deaths are not reported in the registry record. The number of analyses is listed as 0, and statistical methods, multiplicity procedures, interim analyses, and a prespecified analysis plan are not reported.
These limitations concern what can be concluded from the registry entry. They do not establish that omitted procedures were not performed; such details are simply not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Long-Term One Year Use of Alefacept (Amevive®) in Moderate to Severe Chronic Plaque Type Psoriasis — NCT00655564.
- Registry record last updated 2018-09-11; status last verified 2018-08.
- Results first posted 2012-08-03.
- 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
The registry describes a completed phase 4, single-group study of alefacept for moderate to severe chronic plaque psoriasis, sponsored by Wake Forest University. Enrollment was 15. The listed study dates are 2008-05 for start and 2009-12 for primary completion.
The primary endpoint is the number of participants with a 75% PASI reduction from baseline to week 52. The registry lists safety using CD4 counts as a secondary outcome, 2 outcome measures, and 0 analyses. The primary efficacy result and its statistical uncertainty are not reported in the registry record.
For the Alefacept group, 15 participants were at risk for serious adverse events and 2 were affected; 15 were at risk for other adverse events and 8 were affected. Low CD4 cell count and severe allergic contact dermatitis are listed as serious adverse-event terms, each at 6.7%. The study has no listed comparator, and the registry record does not report the analysis population, missing-data approach, or study-specific dosing schedule.