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 Induction of Remission in RA Patients at Low Disease Activity by Additional Infliximab Therapy (Study P04644AM1) (TERMINATED) (NCT00521924), a randomized phase 3 study. The primary outcome is Number of Patients in Remission According to Disease Activity Score (DAS) 28 (< 2.6).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00521924 |
| Phase | Phase 3 |
| Condition | Rheumatoid Arthritis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
Population
Adults with rheumatoid arthritis and low disease activity were eligible. The registry describes low activity as DAS28 >2.8 and <3.5, an age range of >35 to <=65 years, and a stable disease-modifying antirheumatic drug regimen for at least 3 months before treatment.
Intervention
Infliximab was added to basic rheumatoid arthritis treatment. The described regimen was 3 mg/kg at Weeks 0, 2, 6, 14, 22, 30, and 38.
Comparator
The comparison group received basic treatment with disease-modifying antirheumatic drugs and no additional infliximab.
Primary question
Did the groups differ in the number of patients in remission according to DAS28 (<2.6) after 38 weeks? The registry record says the trial terminated early because of poor enrollment and none of the randomized patients reached Week 38. The planned primary outcome therefore could not be analyzed.
This is a question about remission at a specified endpoint, not simply whether disease activity changed at any time. The intervention was an add-on strategy: both groups had basic treatment, while infliximab distinguished the experimental group. The registry also describes secondary interests, including DAS28, quality of life, ACR response, radiographic disease progression, inflammatory markers, and the Simplified Disease Activity Index. Those interests do not substitute for the unavailable primary endpoint result.
3. Trial Design
The registry describes a Phase 3, randomized, open-label, multicenter, parallel-group study in rheumatoid arthritis. Participants were assigned in a 1:1 ratio to basic therapy with or without infliximab. The registry lists enrollment of 8 and identifies Merck Sharp & Dohme LLC as the sponsor. The study started in 2007-06, had primary completion in 2008-04, and is marked terminated.
Participants in the infliximab group were to receive 3 mg/kg alongside basic treatment at Weeks 0, 2, 6, 14, 22, 30, and 38. The planned treatment period was 38 weeks, followed by follow-up of up to 6 months. Basic treatment is described as disease-modifying antirheumatic drugs; the registry names methotrexate, chloroquine, leflunomidum, cyclosporin A, sulfasalazine, and OM 89.
Open-label means that masking was not used, according to the registry. Randomization can help make treatment groups comparable at the outset, while an open-label design means participants and study staff are not kept unaware of assigned treatment. These are general design concepts; the record does not describe further safeguards or methods for limiting bias.
The planned primary assessment was remission according to DAS28 after 38 weeks. The trial terminated early because of poor enrollment. The registry states that none of the randomized patients reached Week 38, so a change in DAS28 between baseline and Week 38 could not be analyzed. The record does not report the planned recruitment target or the reason for the enrollment difficulty beyond poor enrollment.
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 | Infliximab + Basic Treatment | Basic Treatment (DMARDs) |
|---|---|---|
| STARTED | 4 | 4 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 4 | 4 |
Analysis population for the primary outcome, as defined in the registry: This trial terminated early due to poor enrollment. Since none of the randomized patients reached Week 38, no change of DAS28 between baseline and Week 38 could be analyzed.
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 | Infliximab + Basic Treatment | Basic Treatment (DMARDs) | Total |
|---|---|---|---|---|
| Participants analysed | 4 | 4 | 8 | |
| Age, Customized | participants | 4 | 4 | 8 |
| Sex: Female, Male: Female | Participants | 4 | 1 | 5 |
| Sex: Female, Male: Male | Participants | 0 | 3 | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Patients in Remission According to Disease Activity Score (DAS) 28 (< 2.6), measured over after 38 weeks.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the number of patients in remission according to DAS28 (<2.6) after 38 weeks. DAS28 is an assessment of disease activity based on swollen joint count, erythrocyte sedimentation rate, and general health. The registry describes scores from 0 to 10, with lower scores indicating less disease activity.
A remission threshold turns a continuous disease-activity score into a clinically interpretable status at a specified assessment: each participant either meets the stated threshold or does not. The count would describe how many participants in each group met that criterion at the planned endpoint. It would not, by itself, describe the degree of change in participants who did not meet the threshold.
The endpoint is useful for framing the study's stated question about reaching remission, rather than only comparing average scores. However, the assessment requires information at the planned time point. The registry says none of the randomized patients reached Week 38, and no change from baseline to Week 38 could be analyzed. It therefore contains no evaluable primary remission count at the planned endpoint. This absence is not evidence that no participant achieved remission; the endpoint was not assessed as planned.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the primary endpoint could not be analyzed. The trial terminated early because of poor enrollment, and none of the randomized patients reached Week 38. The registry therefore does not report remission counts at the planned endpoint, a comparison between groups, or an estimate of the treatment-group difference.
The enrollment recorded was 8. The adverse-event summary lists 4 participants at risk in each group, but those safety denominators do not provide a Week 38 outcome. In particular, the record does not support treating the absence of a primary endpoint analysis as a remission count of zero in either group. No endpoint assessment at the intended time is reported.
There is consequently no posted estimate of how frequently remission occurred with infliximab plus basic treatment or with basic treatment alone. No confidence interval, p-value, or other statistical test for the primary comparison is reported in the registry record. Without an endpoint estimate, the precision of a treatment contrast cannot be described. The record also does not report an analysis of earlier DAS28 measurements that could answer a different, shorter-term question.
As general statistical context, an effect estimate describes the observed contrast between groups, while a confidence interval expresses the uncertainty around that estimate under the analysis assumptions. A wide interval would indicate limited precision; a narrow interval would indicate greater precision. Neither can be interpreted for this primary comparison because the endpoint data and estimate are absent. A p-value likewise cannot replace the missing estimate or show the size of an effect.
The randomized design specifies how treatment assignment was intended to occur, but randomization alone does not create outcome data. Early termination and the lack of Week 38 assessments prevent a randomized comparison of the primary endpoint in the posted results. The record does not establish whether the planned analysis would have used an adjusted model, how missing endpoint data would have been handled, or which analysis population would have been primary. Those details are not reported in the registry record.
The registry lists secondary areas of interest, including quality of life, ACR response, radiographic disease progression, inflammatory markers, and SDAI. It does not provide analysis results for those areas in the information recorded. They should not be interpreted as evidence for or against an effect. The appropriate reading is limited: this study set out to compare an add-on treatment strategy, but its planned primary endpoint was not observed at the specified time and no comparative efficacy result is posted.
9. Statistical Methods Explained
What does randomization contribute?
The registry describes randomized assignment in a 1:1 ratio. As general statistical context, randomization is intended to reduce systematic differences between groups at the start of a trial. It does not guarantee that every characteristic will be balanced, especially in a small enrolled group, and it does not compensate for outcome data that were never collected at the planned endpoint. Here, the registry lists enrollment of 8 and says none of the randomized patients reached Week 38. Thus, the planned randomized comparison of remission cannot be reconstructed from the assignment method alone.
What does open-label mean for interpretation?
The study is described as open-label, with masking listed as none. In general, knowledge of assigned treatment can affect participant reports, care decisions, or outcome assessment, depending on how outcomes are gathered. The primary endpoint uses DAS28, which incorporates swollen joint count, erythrocyte sedimentation rate, and general health. The registry does not report procedures for blinded assessment or other measures to reduce the possible influence of treatment awareness. This is a design consideration, not a finding that bias occurred.
Why does the endpoint need a group comparison?
The primary endpoint is the number of patients meeting the remission definition, DAS28 <2.6, after 38 weeks. In general, a count within one group describes that group's observed outcomes, whereas a comparison asks how those outcomes differ between assigned groups. A count would need to be paired with its denominator to be interpretable, and a treatment contrast would need uncertainty information to convey precision. The registry does not report the planned endpoint counts or a comparison because no randomized patient reached the specified assessment time.
What would an interval or test tell a reader?
As general statistical context, a confidence interval gives a range of values compatible with the observed data and the method used to construct it. Its width conveys precision, while its location conveys the direction and possible size of the estimated contrast. A hypothesis test addresses compatibility of the data with a specified null hypothesis; a p-value is not an effect size and does not describe clinical importance. No primary endpoint estimate, confidence interval, or p-value is reported in the registry record. These concepts therefore explain how a completed analysis might be read, not a result from this trial.
Why does early stopping matter?
Early termination curtailed observation before the planned primary assessment. In general, fewer observed outcomes mean less information for estimating a treatment contrast, and stopping can also affect which participants contribute data. The registry gives poor enrollment as the reason for termination. It does not report an interim analysis, a stopping boundary, or a statistical stopping rule. It would be inappropriate to infer that termination followed a finding about benefit, lack of benefit, or harm.
How should planning illustrations be understood?
General sample-size planning uses assumptions about the effect to be detected, the error rate, allocation, and the statistical method. A planning illustration is a hypothetical design calculation, not an observed outcome and not a measure of the trial's achieved power. The planning framework described for this record assumes a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect expressed as a fraction of the observed effect. It also distinguishes event totals for time-to-event settings from participants per arm for other settings.
Those assumptions cannot create an observed effect estimate. Since the primary endpoint was not available at Week 38, there is no observed primary effect on which to base a meaningful illustration for that comparison. The registry does not report the trial's own sample-size justification. No planning figure should be read as the number enrolled, the number analyzed, or evidence that a target level of power was achieved.
Which analysis details are unavailable?
The registry record does not report a primary statistical model, covariate adjustment, confidence-interval method, or hypothesis-testing procedure. It also does not report an interim analysis plan, a missing-data method, or the definition of an analysis population. These are distinct elements of a statistical analysis plan. Their absence from the record means they cannot be described as methods used in this trial. The reported randomized design and endpoint definition do not establish what analysis would have been conducted had the planned assessment been reached.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several secondary areas: DAS28 at baseline versus Week 38, quality of life, ACR response, radiographic disease progression, the effect of inflammatory markers on response and disease progression, and SDAI. These are distinct questions and may involve different outcome types or assessment procedures. The record does not report results for these areas in the posted information, nor does it describe a plan for controlling multiplicity across outcomes or analyses.
As general statistical context, examining multiple outcomes can increase the chance that at least one result appears noteworthy by chance if each is tested separately. A prespecified multiplicity strategy can define how to interpret a family of tests. No such strategy is reported, so no adjustment method or hierarchy among outcomes can be attributed to the trial.
Missing endpoint information is central: the record says none of the randomized patients reached Week 38, and the planned change in DAS28 could not be analyzed. It does not describe imputation, a model for incomplete repeated measurements, or another approach to missing data. The reason given for early termination is poor enrollment, but the record does not provide further detail about participant-level follow-up or outcomes before Week 38.
The analysis populations are also not reported. The record does not specify whether the intended primary analysis was based on all randomized participants, participants who received treatment, or another defined group. No assumption about missingness or analysis population should be inferred from the randomized design alone.
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 |
|---|---|---|---|
| Infliximab + Basic Treatment | 0 | 4 | 0.0% |
| Basic Treatment (DMARDs) | 0 | 4 | 0.0% |
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 |
|---|---|
| Infliximab + Basic Treatment | 0 of 4 |
| Basic Treatment (DMARDs) | 0 of 4 |
The registry's safety summary lists 4 participants at risk in the infliximab plus basic treatment group and 4 in the basic treatment group. It reports 0 serious adverse events and 0 other adverse events in each group. These are the posted counts for the categories shown; they do not establish that the study collected safety information over the intended treatment and follow-up periods for every participant.
The death counts are not reported in the registry record. A missing death value should not be read as a count of zero. No serious adverse-event terms are listed. The absence of listed terms is consistent with the posted serious-event counts, but the record does not give additional event narratives or detail on timing, duration, or attribution.
As general context, safety counts are interpreted alongside the number of participants observed and the period of observation. Here, the trial terminated early, and the posted summary should be read as a limited record rather than as a complete account of risks over the planned study duration. The counts do not establish comparative safety beyond the events and denominators recorded.
12. What the Result Does, and Does Not, Mean
The record supports a clear conclusion about study completion: this randomized Phase 3 trial terminated early because of poor enrollment, and none of the randomized patients reached Week 38. The primary remission outcome was therefore not analyzed at the planned time. The record does not provide a comparative estimate of remission for infliximab plus basic treatment versus basic treatment alone.
This does not mean that no participant experienced remission. It means the registry reports no assessment at the planned endpoint from which remission counts could be compared. Similarly, the absence of an efficacy estimate is not evidence of no effect, and it is not evidence of an effect. The available record leaves that primary treatment question unanswered.
The posted safety counts are limited to the listed categories and denominators: 0 serious adverse events and 0 other adverse events among 4 participants at risk in each group. Death counts are not reported in the registry record. These entries do not provide a full estimate of safety during the intended treatment and follow-up period, particularly given early termination.
As general statistical context, conclusions depend on both the observed outcomes and their uncertainty. With no primary endpoint comparison, neither the magnitude nor precision of a remission difference can be described. The randomized allocation and stated outcome definition explain what the study intended to compare, but they are not themselves evidence of a treatment effect. The secondary questions listed in the record also cannot fill this gap without reported analyses.
The appropriate interpretation is therefore about the information available, not about whether infliximab should be used. The trial's planned primary comparison was not completed as specified in the registry record, and the posted information does not establish benefit, lack of benefit, or comparative harm.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the distinction between a planned comparison and an analyzed comparison. A randomized design can specify a meaningful question, a treatment contrast, and a follow-up time, yet still yield no primary estimate if participants do not reach the assessment point. Here, the primary question was framed around remission after 38 weeks, but the registry reports that none of the randomized patients reached Week 38.
The record also shows why outcome timing matters. A score or clinical state measured at another time would not automatically answer the stated question about remission at the planned endpoint. Without the specified observation, a group comparison cannot be estimated from the information recorded. This is a data-availability limitation, not a statistical test result.
Enrollment of 8 and early termination also place the posted safety counts in context. Counts should be interpreted with their denominators and observation period, not treated as a complete account of outcomes over the intended study duration. The registry reports no serious or other adverse events in the listed groups, but deaths are not reported and the planned follow-up was not completed as intended.
Finally, the record distinguishes study design information from results. It identifies randomization, open-label conduct, the endpoint definition, and a reason for termination, but does not report a primary analysis, an uncertainty estimate, or a statistical analysis plan. Recognizing those boundaries prevents a design description or an empty result from being mistaken for evidence about treatment effect.
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 is that the trial did not reach the planned primary endpoint assessment. The registry states that poor enrollment led to early termination and that none of the randomized patients reached Week 38. Consequently, the planned DAS28 remission count and the change from baseline to Week 38 could not be analyzed. No comparative effect estimate or measure of its precision is reported.
The recorded enrollment was 8, which leaves a small enrolled group for describing outcomes even apart from the absent Week 38 assessment. The registry does not report a recruitment target or a sample-size justification, so the intended information target cannot be assessed. A planning illustration based on an observed effect cannot replace a missing observed comparison.
There are also reporting limits. The registry does not describe the primary analysis method, the analysis population, handling of missing data, covariate adjustment, or an interim analysis plan. It does not report a multiplicity strategy for the listed secondary interests. The record therefore cannot establish how an intended statistical analysis would have addressed these issues.
The safety summary contains event counts and group denominators, but death counts are not reported in the registry record. The record does not provide additional detail about the duration or completeness of safety observation after early termination. These limits narrow what can be inferred from the posted counts and prevent a complete account of outcomes over the planned treatment and follow-up period.
Finally, the open-label design is a potential consideration for outcome assessment and reporting, although the registry does not establish that it caused bias. The principal interpretive constraint remains the lack of primary endpoint data at the planned time.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Induction of Remission in RA Patients at Low Disease Activity by Additional Infliximab Therapy (Study P04644AM1) (TERMINATED) — NCT00521924.
- Registry record last updated 2017-04-12; status last verified 2017-03.
- Results first posted 2009-06-01.
- 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
NCT00521924 is a Phase 3 randomized, open-label, multicenter, parallel-group study of rheumatoid arthritis. It compared infliximab added to basic disease-modifying antirheumatic drug treatment with basic treatment alone. Enrollment was 8. The study started in 2007-06, had primary completion in 2008-04, and is marked terminated.
The primary outcome was the number of patients in DAS28 remission (<2.6) after 38 weeks. The registry says the trial terminated early because of poor enrollment and none of the randomized patients reached Week 38, so the planned primary outcome could not be analyzed. The safety summary lists 0 serious and 0 other adverse events among 4 participants at risk in each group; death counts are not reported in the registry record.