Study to Evaluate Arthroplasty Specimens for Osteoarthritis of the Knee and Hip: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study to Evaluate Arthroplasty Specimens for Osteoarthritis of the Knee and Hip (NCT03949673), a na phase 2 study. The primary outcome is Number of Participants by Degree of Synovial Lymphocytic Inflammation.

2. Clinical Question

The study objective was exploratory: to evaluate cellular and connective tissue composition in joints from people with osteoarthritis who had been treated with fasinumab, compared with people treated with placebo or NSAIDs. The primary outcome focuses on synovial inflammatory cells, including lymphocytes, mast cells, neutrophils, and eosinophils. Their presence and degree were to be scored as None present, Slight/Mild, Moderate, or Marked/Band.

The key statistical question is descriptive as well as comparative. A useful comparison would require the number of assessed participants in each inflammation category for each parent-study treatment group, together with enough information to understand how specimens entered the analysis. The registry record does not report those category counts or an analysis comparing groups. It therefore identifies what the investigators intended to examine, but does not establish whether the recorded tissue patterns differed by treatment.

3. Trial Design

The registry record describes a single-group study of arthroplasty specimens from people with knee or hip osteoarthritis. Its arm description identifies participants who were enrolled in the tissue study while participating in an ongoing fasinumab phase 3 parent study. The record lists an enrollment of 23 and a study status of terminated. The study start is 2019-04-08, and primary completion is listed as 2020-08-25.

Although the tissue study is not described as a randomized comparison, the intended descriptive groups reflect treatment received in the parent study: fasinumab, placebo, or NSAIDs. Naproxen, diclofenac, and celecoxib are listed among the interventions. That list does not establish which specific treatments were received by participants whose specimens were evaluated, or how many participants were in each parent-study treatment group. The registry record does not report those group counts.

The primary population is defined as the arthroplasty analysis set: participants enrolled in this study who had histological evaluation data. The outcome is based on treatment received in the parent study, described as an as-treated approach. The stated assessment window is up to 24 weeks from the last dose of study drug in the parent study, an average of approximately 3 months.

The record labels the study phase as phase 2, while its official title refers to the phase 3 fasinumab program. These descriptions concern the tissue study and its parent-study context; the record does not explain the relationship between the phase designation and the parent program. The reason the study was terminated is not reported in the registry record. Allocation, masking, and the study model are recorded as NA, none, and single group, respectively; there is no basis to interpret the tissue groups as randomized, masked, or directly comparable arms.

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: This study only included participants that received at least 1 dose of study drug in one of the 3 parent studies: R475-PN-1523 (NCT02683239), R475-OA-1611 (NCT03161093), or R475-OA-1688 (NCT03304379).

Overall Study

Analysis population for the primary outcome, as defined in the registry: Arthroplasty analysis set: All participants who are enrolled in this study, have histological evaluation data and is based on the treatment received in their parent study (as treated).

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: Arthroplasty analysis set: All subjects who are enrolled in this study, have histological evaluation data and is based on the treatment received in their parent study (as treated).

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants by Degree of Synovial Lymphocytic Inflammation, measured over Up to 24 weeks from the last dose of study drug in the parent study, an average of approximately 3 months.

The primary endpoint is the number of participants by degree of synovial lymphocytic inflammation. It concerns histological assessment of inflammatory cells in joint specimens, including lymphocytes, mast cells, neutrophils, and eosinophils. The stated scoring levels are None present, Slight/Mild, Moderate, and Marked/Band. The endpoint is framed as participant counts, rather than as a continuous measurement of tissue inflammation.

Such a descriptive endpoint can show how assessed specimens are distributed across inflammation grades within treatment groups. It can preserve distinctions between levels of observed inflammation instead of reducing the tissue assessment to a single average. A comparison of those distributions could be relevant to the study objective of evaluating cellular and connective tissue composition in participants with osteoarthritis who received different parent-study treatments.

That general rationale does not establish how the scoring was performed or how differences were to be tested. The registry record does not report the actual category counts, scoring reliability, assessor procedures, or a statistical method for comparing the groups. It also does not report numerical findings for this endpoint. Consequently, the endpoint definition can be described, but its observed distribution and any treatment-group contrast cannot be interpreted from the posted results.

The stated timeframe is up to 24 weeks after the last parent-study dose, with an average of approximately 3 months. This specifies the intended timing relative to parent-study treatment, but does not give the timing for each specimen or the number assessed at each time.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the endpoint count?

The primary endpoint is expressed as the number of participants classified at each degree of synovial lymphocytic inflammation. In general, a count reports how many observations fall into a category; it does not, by itself, describe how uncertain that count is or whether groups differ. To interpret a count across treatment groups, readers need the number assessed in each group and the counts in each category. The registry record does not report those outcome values.

The listed grades are None present, Slight/Mild, Moderate, and Marked/Band. The outcome description also names lymphocytes, mast cells, neutrophils, and eosinophils as inflammatory cells scored by presence and degree. The record does not clarify whether each cell type was scored separately, how scores across cell types were combined, or whether the title’s reference to lymphocytic inflammation is intended to describe the complete scoring procedure. Those details should not be assumed.

Why does the study design matter?

In general, random allocation can help make treatment groups comparable at the start of a study, while masking can reduce the influence of knowledge about treatment on assessment. The registry identifies this as a single-group study with no masking and does not describe a randomized allocation for the tissue comparison. Its treatment groups are defined by treatment received in a parent study. Therefore, a difference between groups would be an association in the observed specimens, not automatically a causal effect of treatment.

Selection into the arthroplasty analysis set is also important. The stated population includes participants who were enrolled and had histological evaluation data. In general, a subset defined by having a specimen and evaluable histology may differ from the larger population in ways that affect a comparison. The record does not report how many participants in each parent-study treatment group entered this set or whether those with and without histology differed.

What does a confidence interval communicate?

In general, a confidence interval gives a range of values compatible with the observed data under the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, while an interval that spans a broad range leaves substantial uncertainty about the underlying quantity. The registry record provides no estimates or confidence intervals for the primary outcome, so there is no reported precision measure to interpret.

For categorical participant counts, uncertainty can depend on the number of observations in each group and on how observations are distributed among categories. Sparse categories can make comparisons unstable. General methods for categorical data may estimate category probabilities or compare distributions, but the registry record does not report which, if any, method was planned or used. The fact that the outcome is described as counts does not identify an analysis model.

How should significance testing be understood?

In general, a p-value measures how compatible the data are with a specified null model, given the assumptions of the analysis. It does not measure the size or clinical importance of an effect, and it cannot remedy bias in group selection or measurement. No p-value, test statistic, or primary-outcome analysis is reported in the registry record. There is therefore no statistical significance result to interpret.

The record lists three outcome measures but gives no analysis count. When a study examines multiple outcomes or multiple contrasts, multiplicity can increase the chance of obtaining at least one apparently unusual result under a set of null hypotheses. A planned strategy might define a primary hypothesis or adjust interpretation across tests. The registry record does not report such a strategy, and no claim about multiplicity control is justified.

What do planning assumptions mean?

The stated planning illustration assumes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the target effect as a stated fraction of the observed effect. In general, a sample-size calculation estimates the amount of information that would be needed to detect an assumed effect under specified assumptions. It is a planning exercise, not a measure of the probability that the completed study found an effect.

The record provides no primary-outcome effect estimate or category counts with which to assess the illustration. Any such planning output should not be interpreted as observed power, as a design justification documented by the investigators, or as evidence that the completed tissue study was sufficiently informative. The registry record does not report the study’s own sample-size justification.

Finally, the study status and absence of analyses limit what statistical conclusions can be drawn. A terminated status does not establish why the study ended or what data were available. The record does not report interim analyses, a prespecified statistical analysis plan, or the handling of missing histology. Without those details and the outcome results, methods can be explained in general, but the analysis actually conducted cannot be reconstructed.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists three outcome measures, but reports zero analyses. It does not describe a plan for controlling multiplicity, prioritizing outcomes, or handling multiple comparisons among parent-study treatment groups or inflammation grades. In general, multiplicity matters when many outcomes or contrasts are tested, because interpreting each result in isolation can overstate the strength of evidence. No multiplicity adjustment or testing hierarchy should be presumed.

The primary population is defined as participants enrolled in the tissue study who had histological evaluation data. This clarifies that the endpoint concerns an analysis subset, but the record does not report the number with histology by treatment group, the number with missing or unusable specimens, or reasons data may be unavailable. Missing-data procedures, including any imputation or sensitivity analyses, are not reported in the registry record.

The treatment classification is as treated according to the parent study. The record does not state how participants with changes in treatment, incomplete treatment information, or other deviations were handled. It also does not report whether the analysis population was restricted in any additional way beyond enrollment and histological data.

The statistical analysis plan, interim analyses, and sample-size justification are not reported in the registry record. The listed planning assumptions do not substitute for a documented justification or analysis plan. As a result, the intended control of false-positive findings, the approach to incomplete histology, and the relationship between the planned and reported analyses cannot be evaluated.

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

The record supports a limited description of study intent and structure. It describes an exploratory evaluation of joint tissue from people with knee or hip osteoarthritis who participated in a parent fasinumab study, and it defines a histological outcome based on degrees of synovial lymphocytic inflammation. It also gives the intended timeframe and the analysis population. These details explain what the investigators sought to assess, not what they found.

The posted results do not report category counts, estimates, confidence intervals, or statistical tests for the primary outcome. Therefore, they cannot show whether the tissue assessments were distributed differently among participants treated with fasinumab, placebo, or NSAIDs. They also cannot establish the magnitude or precision of any difference. The study objective and endpoint definition should not be mistaken for a finding.

Even if comparative tissue values were available, this study’s nonrandomized, as-treated grouping would require cautious interpretation. In general, observed groups can differ for reasons other than the treatment being compared. The registry’s own description warns that these are not like-for-like control arms. The record does not provide enough information to assess the sources or extent of such differences.

The adverse-event fields showing zero participants at risk and affected do not demonstrate an absence of adverse events; they do not provide a usable account of participants at risk. Likewise, the terminated status does not explain why the study ended or whether the endpoint was fully assessed. Those details are not reported in the registry record.

Overall, the available information defines an exploratory question but does not provide evidence with which to answer it. No conclusion about treatment effects, tissue differences, or safety can be drawn from the outcome data posted in the registry record.

12. Why This Trial Matters Statistically

This study is statistically notable because it asks a tissue-composition question within an arthroplasty subset of participants from a parent treatment program. The focus is not only on a clinical outcome but on histological categories in joint specimens. Such work can raise distinctive design and analysis issues: who contributes a specimen, whether evaluation is available for everyone enrolled, how tissue grades are defined, and whether treatment groups are comparable.

The registry record makes the distinction between the tissue study and the parent study important. Treatment groups are based on treatment received in the parent study, and the tissue study is not described as a randomized, masked comparison. In general, this means that descriptive differences among specimens cannot be attributed to treatment without addressing selection and group comparability. The record itself notes that the arms are not a like-for-like control comparison.

The endpoint also illustrates why outcome definitions and outcome results must be distinguished. The record gives a named measure, a timeframe, and an inflammation grading scheme, but does not report the counts or analyses needed to characterize the findings. An endpoint can be clearly specified while the available registry results remain insufficient for statistical interpretation.

Finally, the record lists enrollment of 23, three outcome measures, and zero analyses, with the study marked terminated. These registry entries make transparent reporting of group denominators, specimen availability, analysis methods, and reasons for termination especially relevant. Those details are not reported in the registry record. The main statistical lesson is that a study objective and planned measure are not substitutes for analyzed results, and a planning illustration cannot fill that gap.

13. 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 the absence of primary outcome results. No participant counts by inflammation grade or parent-study treatment group are reported, and the record lists zero analyses. This prevents assessment of the observed tissue distribution, group differences, or statistical precision.

The enrolled population is described in relation to arthroplasty and availability of histological evaluation data. The record does not give treatment-specific denominators or explain how many participants lacked evaluable specimens. It is therefore not possible to assess the degree of selection into the analysis set or how missing histology might affect group comparisons.

The treatment groups are based on treatment received in the parent study, and the record explicitly cautions that they are not a like-for-like control comparison. Allocation is listed as NA and masking as none. The record does not explain how parent-study treatment assignment, specimen availability, or other participant characteristics were addressed analytically. Causal interpretation is not supported by the design description.

The endpoint description lists several inflammatory cell types and several grades, while the outcome title emphasizes synovial lymphocytic inflammation. The record does not clarify the scoring process, whether cell types were assessed separately, or how results were combined. The statistical method for the endpoint is not reported.

The study is marked terminated, with no reason for termination reported. The record also does not provide a statistical analysis plan, interim-analysis information, missing-data procedures, or the study’s sample-size justification. These omissions restrict evaluation of whether the planned methods were followed and how robust any intended conclusions would have been.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Study to Evaluate Arthroplasty Specimens for Osteoarthritis of the Knee and Hip — NCT03949673.
• Registry record last updated 2023-10-17; status last verified 2023-09.
• Results first posted 2023-10-17.
• 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.

17. Record Summary

This is an exploratory study of arthroplasty specimens from participants with knee or hip osteoarthritis who participated in a fasinumab phase 3 parent study. The registry labels the tissue study phase 2, describes a single-group design, and lists enrollment of 23. The study status is terminated; the reason is not reported in the registry record.

The primary outcome is the number of participants by degree of synovial lymphocytic inflammation, scored across stated grades from None present to Marked/Band. The intended analysis population includes enrolled participants with histological evaluation data, classified by treatment received in the parent study. The timeframe is up to 24 weeks after the last parent-study dose, an average of approximately 3 months.

The record lists three outcome measures and zero analyses. It does not report primary outcome counts, comparative estimates, confidence intervals, or statistical tests. The treatment groups are not a randomized like-for-like comparison, and adverse-event fields with zero participants at risk do not establish that no events occurred. The registry record describes the question and measurement plan, but not results sufficient to determine what the specimen assessments showed.