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 Enthesitis With Ultra Sonography Doppler in Spondyloarthropathies Treated With Infliximab (Study P04440) (NCT00686894), a na phase 4 study. The primary outcome is The Number of Enthesitis Between Week 4 and Week 12 Evaluated Using Power Doppler Ultrasonography (PDUS) and Proprietary Software..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00686894 |
| Phase | Phase 4 |
| Condition | Spondylitis, Ankylosing, SpA |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 7 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
Population
The registry lists ankylosing spondylitis and SpA as conditions. Enrollment was 7. Further participant characteristics, such as age, sex, disease duration, baseline enthesitis status, and eligibility details, are not reported in the registry record.
Intervention
The planned drug regimen was infliximab 5 mg/kg by infusion at weeks 0, 2, and 6. The study also used power Doppler ultrasonography (PDUS), with proprietary software specified for assessing the area of hyper-vascularization. The registry describes follow-up for a maximum of 18 weeks or until relapse.
Comparator
This was a single-group study, with allocation recorded as NA. A concurrent control group or alternative treatment is not described. The registry therefore does not support a like-for-like comparison between treatment groups.
Primary question
The planned primary assessment concerned the number of enthesitis between week 4 and week 12, evaluated using PDUS and proprietary software. The study was intended to assess whether PDUS could serve as a reliable marker of enthesitis response and relapse during infliximab treatment. The registry says the study ended early because recruitment was slow and efficacy analyses were not performed. It therefore does not report an answer to that efficacy question.
3. Trial Design
This was a phase 4, single-group study with no masking. Allocation is recorded as NA, and the registry does not describe random assignment or a comparator group. Enrollment was 7. The study began in 2008-01, had a primary completion date of 2008-11, and is recorded as terminated. The stated reason for early termination was slow recruitment.
The planned regimen was infliximab 5 mg/kg at weeks 0, 2, and 6. Participants were to be followed for a maximum of 18 weeks or until relapse. The registry identifies PDUS as a procedure and infliximab as a drug. It does not report whether every enrolled participant received every planned infusion or completed the planned follow-up.
The primary outcome was described as the number of enthesitis assessed between week 4 and week 12 using PDUS and proprietary software. The outcome description specifies two assessment measures: whether vascularization was present, recorded as yes or no, and the area of hyper-vascularization, recorded in mm^2 as a continuous measure. Although the study planned these assessments, the registry states that efficacy analyses were not performed. No efficacy estimate, analysis population, or participant-level outcome results are reported in the registry record.
The single-group structure matters for interpretation. Without a concurrent control group, the study could not directly compare the observed course with an alternative treatment or an untreated group. The registry record also does not describe a statistical analysis plan that would clarify how longitudinal observations, relapse, or the two imaging measures were to be combined.
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 5 mg/kg |
|---|---|
| STARTED | 7 |
| COMPLETED | 1 |
| NOT COMPLETED | 6 |
Reasons for not completing this period:
| Reason | Infliximab 5 mg/kg |
|---|---|
| Relapse | 2 |
| Protocol Violation | 4 |
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 5 mg/kg |
|---|---|---|
| Participants analysed | 7 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 7 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 6 |
6. Primary Endpoint
The registry lists the primary outcome as The Number of Enthesitis Between Week 4 and Week 12 Evaluated Using Power Doppler Ultrasonography (PDUS) and Proprietary Software., measured over 8 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Number of Enthesitis |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was described as the number of enthesitis between week 4 and week 12, evaluated using PDUS and proprietary software. The assessment description gives two components. Vascularization was recorded as present or absent, while the area of hyper-vascularization was measured continuously in mm^2. These measures describe imaging findings at entheses, the sites where tendons or ligaments attach to bone.
In general, an imaging endpoint can provide a structured way to track a feature of disease over time. A yes-or-no assessment records whether a feature is detected, while a continuous area measurement can capture variation in its extent. The registry’s stated aim was to assess whether PDUS could be a reliable marker of enthesitis response and relapse during infliximab treatment. Reliability would concern how consistently the measurement reflects the feature being assessed; the registry does not report reliability results.
The endpoint wording does not specify how the two imaging components were combined into a single count or summary, or how repeated assessments were to be handled. Those details are not reported in the registry record. Most importantly, the outcome description states that efficacy analyses were not performed after early termination for slow recruitment. The planned endpoint therefore has no reported efficacy result in this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record describes a planned imaging study, not a completed efficacy analysis. Its central question was whether PDUS could be a reliable marker of enthesitis response and relapse in participants treated with infliximab. The registry says that recruitment was slow, the study was terminated early, and efficacy analyses were not performed. Consequently, there is no reported estimate of change in enthesitis, no comparison of response or relapse over time, and no statistical result from which to judge the planned endpoint.
The enrollment figure is 7. That number describes enrollment, not necessarily the number with complete imaging, the number included in a particular analysis, or the number with complete follow-up. Those analysis details are not reported in the registry record. Likewise, the planned follow-up duration does not establish how long participants were actually observed.
The study had a single-group design and no masking. Because a control group is not described, the record cannot provide a direct comparison with another treatment or with no treatment. A change observed within a group, even if reported, would not by itself distinguish a treatment-related change from other explanations such as natural variation, measurement variability, or changes over time. In this record, even a within-group efficacy result is absent.
The outcome description identifies both a binary vascularization assessment and a continuous area assessment. The record does not report results for either component or explain how they would contribute to the primary count. It also does not report confidence intervals, p-values, or an effect estimate. Without those results, there is no basis for assessing the magnitude or precision of any treatment-associated imaging change.
Any planning illustrations based on an observed effect should be read as planning exercises, not as observed power or evidence that the trial tested its efficacy question successfully. The described planning assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those assumptions do not match the registry’s single-group design. The registry record does not report an efficacy analysis from which to interpret an observed effect in this study.
Overall, the registry documents the intended question, treatment schedule, imaging measures, and early termination, but not an efficacy answer. It does not establish whether PDUS tracked enthesitis response or relapse in this study, nor how precisely such a relationship could have been estimated.
9. Statistical Methods Explained
The registry identifies the study as single-group, unmasked, and without a listed allocation scheme. It reports no efficacy analyses. The statistical concepts below are general explanations of how the described measurements could be approached; they are not claims about analyses that were conducted for this study. The analysis methods actually planned, beyond the brief outcome description, are not reported in the registry record.
What does the endpoint measure?
The primary outcome combines language about a number of enthesitis with two imaging features: vascularization, recorded as yes or no, and area of hyper-vascularization, measured continuously in mm^2. These data types carry different statistical information. A binary observation distinguishes detection from non-detection. A continuous observation records an amount on a measurement scale. A count outcome records how many events or findings occur within a defined unit or observation period.
In general, analysis should respect the type of measurement. A binary outcome is often summarized by the number or proportion of observations in each category. A continuous outcome may be summarized with a measure of central tendency and variability, depending on its distribution. A count outcome may be summarized by its frequency distribution or a rate when the observation time is relevant. These are general options, not reported methods for this trial. The registry does not state how the vascularization and area measurements were converted into the primary count, whether each enthesis was a separate unit of analysis, or how repeated observations were handled.
Why does the study design matter?
A single-group study can describe outcomes among people observed under a treatment regimen, but it does not create a concurrent contrast with an alternative group. In general, a randomized comparison helps separate treatment-group differences from differences in participant characteristics and other influences. This record lists no comparator and no random allocation. Any hypothetical within-group change would therefore have limited ability to establish what would have happened over the same period under another condition. Here, the registry reports no efficacy analysis or change estimate at all.
The absence of masking may also be relevant to measurement. In general, knowledge of treatment or study timing can influence judgments when measurements involve interpretation. The registry does not describe who performed or read the ultrasound assessments, whether readers were masked to visit or clinical information, or what procedures were used to support consistent scoring. These matters are not reported in the registry record and should not be assumed either way.
What do uncertainty measures tell a reader?
In general, a confidence interval gives a range of values compatible with an estimate under a statistical model and conveys uncertainty about the estimated effect. A narrow interval indicates greater precision than a wide interval, though interpretation also depends on the endpoint and study design. A p-value addresses how compatible the observed data are with a specified null model; it is not a measure of effect size, clinical importance, or the probability that a treatment works. The registry reports no efficacy estimate, confidence interval, or p-value for the primary outcome. Statistical precision therefore cannot be assessed from the efficacy record.
For count outcomes, general models may need to account for the relationship between the mean and the variability. Over-dispersion occurs when count variability is greater than a simple model assumes; ignoring it can make uncertainty appear smaller than it is. Repeated measurements on the same participant may also be correlated, so treating every measurement as independent can misstate precision. The registry does not report whether these features were assessed or what model, if any, was planned.
How should planning calculations be read?
Sample-size calculations are prospective planning tools: they describe the number of observations a hypothetical design might require under specified assumptions. They are not a measure of the power actually achieved after a trial, and they do not substitute for an estimated treatment effect with uncertainty. The planning assumptions associated with this record describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and detection of a stated fraction of an observed effect. These are assumptions for a planning illustration, not the design described in the registry, which is single-group.
Any number of participants per arm for a specified power should therefore be interpreted as a hypothetical design quantity, not as a result from this study. In particular, the planning structure with two arms does not match the listed study structure. The registry also reports that efficacy analyses were not performed, so the record supplies no efficacy result to interpret as a treatment effect. Planning calculations do not resolve that absence or establish that the intended marker question was answered.
In summary, general statistical methods can explain what analyses might suit binary, continuous, and count data, and why design and repeated-measure structure matter. But the registry does not report an efficacy analysis plan or results detailed enough to identify a method used, assess assumptions, or quantify uncertainty for the primary endpoint.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 1 outcome measure and describes two imaging components within the primary outcome: vascularization recorded as yes or no, and area of hyper-vascularization measured continuously. It does not report whether these components were separate inferential tests, combined into a composite, or used in a particular hierarchy. The multiplicity strategy, if any, is not reported in the registry record.
In general, testing multiple outcomes or time points can increase the chance of obtaining a seemingly notable result by chance. A prespecified testing hierarchy or adjustment can address that issue, but no such approach is described. The registry identifies the primary assessment interval as between week 4 and week 12 and gives the timeframe as 8 weeks. It does not state how visits within that interval, or assessments related to relapse, would have entered an analysis.
Missing-data handling is also not reported. The planned follow-up was a maximum of 18 weeks or until relapse, but the record does not say whether participants completed follow-up, which imaging measurements were available, how missing visits would be treated, or whether an imputation method was planned. Enrollment of 7 does not establish how many participants had usable primary outcome data.
The registry does not define analysis populations, such as which participants would be included in an efficacy analysis or how deviations from the planned infusion schedule would be handled. It does not report an efficacy analysis, so the record cannot clarify these choices through an analysis description. These omissions limit assessment of how the intended endpoint and incomplete observation would have been addressed.
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 5 mg/kg | 0 | 7 | 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 5 mg/kg | 2 of 7 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Infliximab 5 mg/kg |
|---|---|---|
| Vertigo | Ear and labyrinth disorders | 1 of 7 |
| Constipation | Gastrointestinal disorders | 1 of 7 |
| Nausea | Gastrointestinal disorders | 1 of 7 |
| Oral Herpes | Infections and infestations | 1 of 7 |
| Pruritis | Skin and subcutaneous tissue disorders | 1 of 7 |
| Pruritis Generalised | Skin and subcutaneous tissue disorders | 1 of 7 |
| Rash | Skin and subcutaneous tissue disorders | 1 of 7 |
| Skin Plaque | Skin and subcutaneous tissue disorders | 1 of 7 |
The registry’s adverse-event record lists the infliximab 5 mg/kg group with 7 participants at risk for serious adverse events and 0 serious adverse events. For other adverse events, it lists 7 at risk and 2 affected. Deaths are recorded as null, and no top serious-event terms are listed. These are the registry’s reported safety figures; they do not provide a detailed account of event types, timing, severity, or relationship to treatment.
A count of 0 recorded serious adverse events should not be read as proof that serious harms cannot occur. In general, safety counts from a small study can be imprecise, and an absence of recorded events in this record cannot establish the absence of risk. The record does not explain whether adverse-event collection was complete through the planned follow-up or provide participant-level details. It also does not report a separate safety analysis.
The 2 other adverse events are not characterized in the listed summary, so their nature and clinical significance cannot be inferred. Safety counts should be considered alongside the study’s early termination, limited enrollment, and the absence of reported efficacy analyses. They describe recorded events in this study, not a comparison of safety between treatments.
12. What the Result Does, and Does Not, Mean
The registry record documents a phase 4, single-group study intended to examine PDUS as a marker of enthesitis response and relapse during infliximab treatment. It specifies a planned infliximab schedule, follow-up period, and primary imaging assessment. It also reports that the study ended early because recruitment was slow and that efficacy analyses were not performed.
That distinction is central to interpretation. A planned outcome is not an observed result. The record does not report whether the number of enthesitis changed, whether vascularization or hyper-vascularization area changed, or whether any imaging measure tracked relapse. It therefore cannot establish whether PDUS was a reliable marker in this study. No estimate or interval is available to show the size or precision of a possible relationship.
The single-group design also means there is no concurrent comparator in the registry record. Even if a change had been reported, a within-group observation alone would not provide a direct estimate of how outcomes differed from an alternative condition. The lack of masking is recorded, but details about assessment procedures and reader masking are not reported.
The safety figures describe 0 serious adverse events and 2 other adverse events among the listed group, with 7 participants at risk for each category. These figures are descriptive and do not support a comparative safety conclusion. The record provides no detailed terms for the other adverse events and no listed serious-event terms.
Planning calculations are not substitutes for trial results. Their stated two-arm, equal-allocation assumptions do not reflect the single-group design, and they should not be read as observed power. The record is most informative about what the investigators intended to measure and why the study stopped, rather than about treatment efficacy or the performance of the imaging marker.
13. Why This Trial Matters Statistically
This study is statistically informative because its stated aim concerns measurement as well as treatment. It was intended to assess whether PDUS could reliably mark enthesitis response and relapse during infliximab treatment. That is not identical to asking whether treatment changes a clinical outcome: it also requires a clear definition of the imaging features, a consistent measurement process, and an analysis linking those measurements to response or relapse. The registry describes the intended imaging components but reports no efficacy analysis.
The record also illustrates why a trial’s design and its analysis question need to align. A single-group study can document observations under a regimen, but it cannot provide a direct between-group contrast. Meanwhile, planning illustrations based on equal allocation between two arms do not describe the listed single-group design. Readers need to distinguish hypothetical design calculations from the actual structure of a study.
Early termination for slow recruitment is another important context. With enrollment of 7 and no efficacy analyses, the record offers no estimate of the imaging outcome’s behavior under the planned regimen. This is not evidence that PDUS did or did not perform well; it is an absence of reported efficacy evidence from this study.
Finally, the entry emphasizes that registry outcomes can be more detailed than the results available for interpretation. It identifies binary and continuous imaging measures, but does not report their results, the intended analysis details, missing-data handling, or analysis populations. Those gaps limit what statistical conclusions can be drawn, even when the research question and measurement goals are clearly stated.
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 principal limitation for interpreting this study is that efficacy analyses were not performed. The registry therefore contains no efficacy estimate for the primary outcome, no uncertainty interval, and no reported test result. The stated aim of evaluating PDUS as a marker of response and relapse remains unanswered in the efficacy record.
Enrollment was 7, and the study was terminated early because recruitment was slow. The registry does not report how many participants had complete imaging, how many completed the planned follow-up, or how many contributed to each outcome measure. It also does not state whether all planned infusions were administered. The planned schedule and follow-up should not be mistaken for confirmed treatment exposure or actual observation time.
The single-group, unmasked design offers no concurrent control for comparison. The registry does not describe how ultrasound readers were selected, whether assessments were blinded to visit or clinical status, or how measurement consistency was evaluated. These details are particularly relevant to an aim focused on marker reliability, but they are not reported in the registry record.
The outcome description names binary vascularization and continuous hyper-vascularization area, but does not explain how these were combined into the number of enthesitis, how repeated observations were handled, or how relapse was incorporated. Multiplicity procedures, missing-data methods, analysis populations, and a detailed statistical analysis plan are also not reported. These limitations prevent assessment of the intended analysis beyond its stated measurement components.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Enthesitis With Ultra Sonography Doppler in Spondyloarthropathies Treated With Infliximab (Study P04440) — NCT00686894.
- Registry record last updated 2017-03-13; status last verified 2017-01.
- Results first posted 2010-03-05.
- 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 phase 4 study enrolled 7 and is recorded as terminated after slow recruitment. It used a single-group, unmasked design, with infliximab 5 mg/kg planned at weeks 0, 2, and 6 and follow-up for a maximum of 18 weeks or until relapse.
The primary assessment concerned the number of enthesitis between week 4 and week 12 using PDUS and proprietary software. The outcome description includes vascularization recorded as yes or no and hyper-vascularization area measured in mm^2. The stated objective was to assess PDUS as a marker of enthesitis response and relapse.
The registry says efficacy analyses were not performed. It lists 0 serious adverse events and 2 other adverse events among 7 at risk in the infliximab group. No efficacy conclusion or comparative treatment estimate can be drawn from the reported record.