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Osteoarthritis, Hip Phase 3 Continuous Endpoint NCT03793010

Study to Evaluate the Efficacy and Safety of FX006 in Patients With Hip Osteoarthritis: Complete Statistical Analysis

This analysis examines the registry results for a randomized, placebo-controlled study of FX006 in people with hip osteoarthritis. It focuses on the Week 12 WOMAC pain-score change, the reported between-group estimate, and the limits of interpreting the available results.

Trial start: 2018-12-12  ·  Enrollment: 70  ·  Sponsor: Pacira Pharmaceuticals, Inc
Scope of this record

This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.

1. Trial at a Glance

This page covers the registry results for Study to Evaluate the Efficacy and Safety of FX006 in Patients With Hip Osteoarthritis (NCT03793010), a randomized phase 3 study. The primary outcome is Change in WOMAC A (Pain) Score at Week 12.

70
Enrollment
Phase 3
2
Arms
In the primary outcome
n/a
Effect
No re-analysis shown
n/a
95% CI
See limitations
FeatureRegistry value
ClinicalTrials.gov identifierNCT03793010
PhasePhase 3
ConditionOsteoarthritis, Hip
AllocationRandomized
Design modelParallel
MaskingQuadruple
Enrollment70
Arms in the primary outcome2
Lead sponsorPacira Pharmaceuticals, Inc
Results postedYes

2. Clinical Question

Population

Patients with hip osteoarthritis. The primary-outcome description says the analysis included patients who received a full dose of study drug assigned to the FX006 32 mg arm or the placebo arm.

Intervention

A single intra-articular injection of FX006 32 mg.

Comparator

Normal saline, used as the placebo comparator.

Primary question

How did the average WOMAC A pain score change from baseline to Week 12 in each randomized group, and what between-group difference was reported?

The study addressed pain in patients with hip osteoarthritis, using the WOMAC A score as its primary outcome. The measure averages responses to five pain questions. Each question ranges from 0, no pain, to 10, extreme pain. The endpoint is the change in that average score from baseline to Week 12.

The registry reports least-squares mean changes of -1.85 for FX006 and -2.16 for normal saline. It also reports a mean difference in final values of 0.31, with a 95% confidence interval from -1.20 to 1.81. These are distinct reported quantities: the group outcome is described as change from baseline, while the between-group analysis is labelled as a difference in final values. The record does not report a p-value for that comparison.

The clinical question is therefore about the measured score and the precision of its estimated between-group contrast. The registry record does not report a threshold for a clinically important difference, so these estimates alone do not establish whether a score difference would matter to patients. They also do not support conclusions about outcomes beyond the stated Week 12 assessment.

3. Trial Design

This was a Phase 3, randomized, quadruple-masked, parallel-group, placebo-controlled study in patients with hip osteoarthritis. The registry names Pacira Pharmaceuticals, Inc as the sponsor. The study began on 2018-12-12, had a primary completion date of 2019-08-07, and is listed as terminated. The reason for termination is not reported in the registry record.

The brief summary describes a two-part study. It says approximately 70 patients would be enrolled in Part I and approximately 440 in Part II, with random assignment in each part to FX006 32 mg or normal saline in equal proportions. Each participant was to receive a single intra-articular injection. The registry's enrollment field lists 70; the record does not explain how that enrollment relates to the planned two-part study or provide a breakdown by part.

Randomization is intended to make treatment groups comparable on average, while masking is intended to limit the influence of treatment knowledge on care, assessment, and reporting. The registry identifies the masking level as quadruple but does not specify which roles were masked. A parallel-group design assigns each participant to one treatment group rather than comparing multiple treatments within the same participant.

The primary outcome was change in WOMAC A pain score from baseline to Week 12. The registry also names change in WOMAC C function score and PGIC score at Week 12 as secondary outcomes. It reports 68 patients in the safety analysis and 55 with Week 12 assessments included in primary and secondary outcome analyses. The primary-outcome arm counts are 24 for FX006 and 31 for normal saline. Additional details about randomization procedures, allocation concealment, and the conduct of each study part are not reported in the registry record.

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

StageFX006Normal Saline
STARTED3535
Randomized But Not Dosed20
COMPLETED78
NOT COMPLETED2827

Reasons for not completing this period:

ReasonFX006Normal Saline
Withdrawal by Subject57
Withdrawn by Investigator or Sponsor1918
Lost to Follow-up12
Patient couldn't sit still for injection10
Withdrew to pursue other treatment10
Did not meet eligibility criteria10

Analysis population for the primary outcome, as defined in the registry: All patients who received a full dose of study drug assigned to the FX006 32 mg arm and the placebo arm were included in the analysis. 68 total patients were included in the safety analysis. 55 of 68 patients had Week 12 assessments and are included in the primary and secondary outcomes analysis.

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: All patients who received a full dose of study drug assigned to the FX006 32 mg arm and the placebo arm were included in the analysis. 68 total patients were included in the safety population.

CharacteristicUnitFX006Normal SalineTotal
Participants analysed333568
Age, Continuousyears59.6 (SD 9.45)61.8 (SD 7.99)60.7 (SD 8.73)
Sex: Female, Male: FemaleParticipants202141
Sex: Female, Male: MaleParticipants131427
Ethnicity (NIH/OMB): Hispanic or LatinoParticipants448
Ethnicity (NIH/OMB): Not Hispanic or LatinoParticipants283159
Ethnicity (NIH/OMB): Unknown or Not ReportedParticipants101
Race (NIH/OMB): American Indian or Alaska NativeParticipants101
Race (NIH/OMB): AsianParticipants011
Race (NIH/OMB): Native Hawaiian or Other Pacific IslanderParticipants000
Race (NIH/OMB): Black or African AmericanParticipants8816
Race (NIH/OMB): WhiteParticipants242650
Race (NIH/OMB): More than one raceParticipants000
Race (NIH/OMB): Unknown or Not ReportedParticipants000
Region of Enrollment: United StatesParticipants333568
Body Mass Index (BMI)kg/m230.50 (SD 5.679)31.29 (SD 5.775)30.91 (SD 5.699)

6. Primary Endpoint

The registry lists the primary outcome as Change in WOMAC A (Pain) Score at Week 12, measured over Baseline and Week 12.

ElementRegistry entry
Result typeLeast Squares Mean
Measure of spread95% Confidence Interval
Unitscore on a scale
Endpoint classificationContinuous Endpoint

The primary endpoint is the change from baseline to Week 12 in the average WOMAC A pain score. WOMAC A is calculated from five pain questions, each scored from 0, no pain, to 10, extreme pain. The registry describes the outcome as a continuous score and reports least-squares means with 95% confidence intervals.

A change score expresses how the measured value at follow-up differs from the baseline value. In this scale, a negative change corresponds to a lower average pain score at Week 12 than at baseline. The reported least-squares mean changes are -1.85 for FX006 and -2.16 for normal saline. Their confidence intervals are -2.99 to -0.71 and -3.22 to -1.09, respectively.

WOMAC A provides a structured way to quantify pain using the same questions across participants. A continuous score can capture variation across a range rather than reducing each participant's experience to a yes-or-no category. The registry does not report why this particular endpoint or Week 12 was selected, or a threshold for interpreting the size of a change as clinically important.

The endpoint is a score-based measure, not a direct count of events or a measure of every aspect of hip osteoarthritis. It also represents one assessment time. The record names function and PGIC as secondary outcomes, but their numerical results are not included in the information reported for this analysis.

7. Why No Re-analysis Is Shown

Reported as posted, not recalculated. Values missing or not estimable for a two-arm comparison (continuous endpoint). A result is recalculated only when the posted data support a clean two-arm comparison, so no result is shown beyond what the sponsor posted.

8. Statistical Interpretation

Clinical Biostats interpretation

The registry reports a least-squares mean change in WOMAC A pain score of -1.85 for FX006, with a 95% confidence interval from -2.99 to -0.71. For normal saline, the corresponding estimate is -2.16, with a 95% confidence interval from -3.22 to -1.09. Both estimates are changes from baseline to Week 12 on a scale where lower scores indicate less pain.

The reported between-group analysis is labelled Mean Difference (Final Values). Its estimate is 0.31, and its 95% confidence interval runs from -1.20 to 1.81. The confidence interval includes zero. In general, when a confidence interval for a difference includes zero, the data are compatible with values on either side of no difference under the analysis used. That interval also spans effects of varying size, so the estimate is not precise enough to confine the possible difference to a narrow range. The registry does not report a p-value for this comparison.

The arm-level estimates and the between-group estimate should not be treated as interchangeable. The endpoint is described as change from baseline, whereas the posted comparison is explicitly labelled as a difference in final values. The analysis method is not named. The record therefore does not establish from the posted description whether the between-group comparison is adjusted for baseline or otherwise calculated in the same way as the arm-level least-squares mean changes.

The confidence intervals around each arm estimate describe uncertainty in those group estimates; they are not a substitute for the confidence interval for a between-group contrast. In general, overlap or non-overlap between separate arm intervals does not by itself provide the same information as an interval calculated directly for the contrast. The direct contrast and its interval are the relevant posted quantities for assessing the estimated between-group difference.

The analysis population was limited to 55 participants with Week 12 assessments, although the safety analysis included 68. The registry does not report why Week 12 assessments were unavailable for some participants or how missing outcome data were handled. If the observed participants differ systematically from those without assessments, estimates based on observed assessments may not represent the full analysis population. The record does not provide enough detail to assess that possibility.

These results describe a measured score at a specified follow-up point, rather than all possible outcomes or longer-term effects. There is no reported clinically important difference threshold, and the record does not include a formal statement about clinical relevance. The estimates should therefore be read as statistical summaries with uncertainty, not as a standalone judgment about the practical importance of the score changes.

9. Statistical Methods Explained

What does a least-squares mean represent?

General explanation: a least-squares mean is a model-based estimate of a group average. Depending on the analysis model, it can account for specified factors such as baseline measurements or design variables. It is not necessarily identical to a simple arithmetic average of the observed values. The registry identifies the primary outcome estimates as least-squares means, but the model, included covariates, and estimation details are not reported in the registry record. It is therefore not possible to determine which adjustments, if any, underlie these estimates.

The posted least-squares mean changes are -1.85 for FX006 and -2.16 for normal saline. The registry gives a 95% confidence interval for each estimate. These intervals express uncertainty about the corresponding estimated group change under the analysis; they do not show the range of individual participants' changes. Individual outcomes may vary more widely than uncertainty around a group mean suggests.

How should the confidence intervals be read?

General explanation: a confidence interval gives a range of estimates compatible with the observed data and the statistical procedure used. A narrower interval indicates greater precision than a wider interval, while a wide interval leaves more uncertainty about the size and direction of the underlying quantity. A 95% confidence interval is not a statement that there is a 95% probability that the particular fixed effect lies within the reported bounds.

The arm-level intervals are -2.99 to -0.71 for FX006 and -3.22 to -1.09 for normal saline. The reported interval for the final-value mean difference is -1.20 to 1.81. The latter concerns a between-group contrast and is the interval to use when describing uncertainty in that reported comparison. Its inclusion of zero means the interval does not rule out no difference under the stated contrast and analysis. The registry does not report the method used to construct this interval.

Why does the contrast definition matter?

The primary outcome is described as change from baseline, but the posted comparison is labelled Mean Difference (Final Values). A contrast based on final values and one based on changes from baseline can represent different estimands, meaning different quantities the analysis aims to estimate. An adjusted model may also estimate a contrast that differs from a simple subtraction of group summaries. General statistical interpretation depends on knowing what quantity is being compared and how it was estimated.

The registry does not name the method for the reported analysis or explain its relationship to the least-squares mean change estimates. A recalculated two-arm continuous comparison is not available because the posted summary statistics are missing or not estimable for that calculation. No alternative unadjusted contrast should be constructed from quantities that may not represent the same estimand. The registry's posted contrast can be described as reported, while its analytic details remain unclear.

What does randomization contribute?

General explanation: random assignment is intended to reduce systematic differences between treatment groups at the time of assignment. It does not guarantee that every group characteristic will be identical, especially in a study with a limited number of participants. Masking can reduce bias that might arise if participants or study personnel know which treatment was assigned. The registry calls the study randomized and quadruple-masked, but does not describe the sequence-generation process, allocation concealment, or the specific groups of people who were masked.

Parallel-group assignment means participants were assigned to one of the treatment groups. The record describes FX006 32 mg and normal saline as the study treatments, with one injection planned for each participant. The available summary does not give further operational details about treatment administration or adherence.

What cannot be inferred from the reported analysis?

The registry does not report a p-value for the between-group estimate, the statistical model, a prespecified analysis plan, or whether any interim analyses were conducted. It also does not report a sample-size justification or the assumptions used in the original trial planning. Those details should not be inferred from the observed group estimates or from generic features of a randomized study.

General explanation: statistical significance and clinical importance are different ideas. A statistical interval concerns uncertainty under a model and analysis; clinical importance concerns whether an effect is meaningful in context. A clinical-importance threshold is not reported in the registry record. The confidence interval alone cannot establish such a threshold or replace clinical judgment about the relevance of a score difference.

The numerical analysis also depends on which participants contribute outcome data and how missing values are addressed. The registry states that 55 participants had Week 12 assessments and were included in primary and secondary outcome analyses. It does not report a missing-data method, sensitivity analysis, or the reasons assessments were unavailable. Consequently, the reported estimates can be described for the analyzed data, but the robustness of those estimates to missing outcomes cannot be assessed from the record.

10. Analyses Reported by the Sponsor

MethodEstimate95% CIP-value
not statedMean Difference (Final Values) 0.31-1.20 to 1.81not reported

The registry reports a mean difference in final values of 0.31, with a 95% confidence interval from -1.20 to 1.81. It does not name the method used for that analysis, and it does not report a p-value. The posted analysis is therefore the available between-group estimate, but the record does not provide enough methodological detail to reproduce or fully evaluate it.

A simple recalculation of the two-arm continuous comparison is not available because the posted summary statistics are missing or not estimable for that calculation. The arm-level least-squares mean changes and their confidence intervals do not necessarily define the same contrast as a difference in final values. Reconstructing a contrast from those quantities could conflate distinct estimands, so no recalculated result is stated.

The record does not flag a discrepancy between a recalculation and the reported analysis. The reported estimate should be read on its own stated terms: a final-value mean difference with the given interval. Because the interval includes zero and extends in both directions, it leaves uncertainty about the direction and size of the contrast. The lack of a method description limits further comparison between the reported contrast and the change-from-baseline endpoint.

11. Multiplicity, Missing Data and Analysis Populations

The registry names two secondary outcomes: change in WOMAC C function score at Week 12 and PGIC score at Week 12. It reports three outcome measures and three analyses, but the numerical results for those secondary outcomes are not included in the reported information. Their estimates, uncertainty intervals, and any p-values are not reported in the registry record.

When multiple outcomes or comparisons are assessed, the chance of obtaining at least one apparently unusual result can increase. General statistical practice may address this through a prespecified testing hierarchy or adjustment procedure, but the registry record does not report whether either approach was used. It does not describe a multiplicity plan, designate confirmatory versus exploratory secondary analyses, or state whether any adjustments were made. The missing details mean the family of analyses cannot be interpreted as a single confirmatory testing strategy.

The primary outcome population is described as patients who received a full dose of study drug assigned to the FX006 32 mg arm or placebo. The record states that 68 participants were included in the safety analysis and that 55 of those participants had Week 12 assessments and were included in primary and secondary outcome analyses. The primary-outcome arm counts are 24 for FX006 and 31 for normal saline.

The record does not explain why Week 12 assessments were unavailable for some participants, whether those participants differed from those assessed, or how missing outcome values were handled. Imputation, likelihood-based methods, sensitivity analyses, and assumptions about missingness are not reported in the registry record. Without these details, the impact of missing assessments on the estimated group contrast cannot be evaluated.

The record also does not report whether the primary analysis followed an intention-to-treat principle, how protocol deviations were handled, or whether any participants were excluded after randomization beyond the stated full-dose analysis description. These omissions limit understanding of the analysis population and the relationship between assigned treatment and the reported estimates.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

ArmParticipants with serious adverse eventsParticipants at riskPercentage
FX0060330.0%
Normal Saline0350.0%

Deaths

ArmDeaths (participants affected of at risk)
FX0060 of 33
Normal Saline0 of 35

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

ArmParticipants affected of at risk
FX00621 of 33
Normal Saline14 of 35

Most frequent non-serious adverse event terms

Event termOrgan systemFX006Normal Saline
ArthralgiaMusculoskeletal and connective tissue disorders8 of 331 of 35
Blood Pressure IncreasedInvestigations2 of 331 of 35
DysphagiaGastrointestinal disorders2 of 330 of 35
BronchitisInfections and infestations1 of 331 of 35
Blood Pressure Diastolic IncreasedInvestigations1 of 331 of 35
Weight IncreasedInvestigations2 of 330 of 35
Back PainMusculoskeletal and connective tissue disorders1 of 331 of 35
Lumbar RadiculopathyNervous system disorders2 of 330 of 35
ThrombocytopeniaBlood and lymphatic system disorders1 of 330 of 35
Dry MouthGastrointestinal disorders1 of 330 of 35
Do not overextend the safety comparison. Serious-adverse-event counts are safety observations, not efficacy outcomes, and should not be combined with the primary result into a single benefit-risk number.

The safety figures are reported for 33 participants at risk in the FX006 group and 35 in the normal saline group. The record reports zero serious adverse events in each group and zero deaths in each group. It reports other adverse events affecting 21 participants in the FX006 group and 14 in the normal saline group.

These counts describe the safety population recorded for the study. The registry does not provide the serious-event terms, and no top serious adverse-event terms are listed. It also does not provide event-level detail, severity classifications for the other adverse events, or information about how long participants were followed for safety. The counts alone therefore do not describe the types, timing, or clinical course of reported events.

General explanation: an observed count of zero is not proof that an event cannot occur. Safety comparisons also depend on the number of participants observed, the duration and completeness of follow-up, and how events were defined and collected. The registry does not report a formal comparative safety analysis, so the counts should not be converted into a claim that one group had a higher or lower risk. They are descriptive figures for the recorded study groups.

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

The posted results establish that the registry reports Week 12 WOMAC A change estimates for the analyzed participants, along with a between-group mean difference in final values. The least-squares mean changes were -1.85 for FX006 and -2.16 for normal saline. The reported final-value mean difference was 0.31, with a 95% confidence interval from -1.20 to 1.81. The interval includes zero and permits uncertainty in either direction.

Those details do not establish the precise size of a treatment effect. The interval is broad enough to include a range of possible contrasts, and the registry does not report a p-value or the method for the comparison. The arm-level estimates concern change from baseline, while the reported between-group contrast is labelled as a difference in final values. Without additional analytic detail, the two descriptions should not be collapsed into a single calculation.

The results also do not show whether a difference is clinically important. No clinically important threshold is reported. The endpoint is a score-based pain measure assessed at Week 12; it is not a complete account of symptoms, function, durability, or other outcomes. The named secondary outcomes do not have numerical results in the information reported for this analysis.

Nor do these data settle how missing assessments affect the estimates. The primary and secondary outcome analyses included participants with Week 12 assessments, while the safety analysis included more participants. Reasons for missing assessments and methods for handling missing data are not reported. The outcome estimates should therefore be interpreted in the context of the analyzed population and these uncertainties.

Finally, the registry status is terminated, and the listed enrollment is 70. The record does not report why the study was terminated or how its two planned parts were completed. Those details do not by themselves explain the observed results. Overall, the posted statistics describe the analyzed measurements and their uncertainty; they do not support a broad conclusion about clinical benefit, lack of benefit, or comparative safety.

14. Why This Trial Matters Statistically

This trial illustrates why the definition of an estimand matters. The primary outcome is described as change from baseline, whereas the posted between-group analysis is labelled as a difference in final values. These quantities can differ, and the registry does not identify the model or explain how the contrast was constructed. Readers can report the estimate as posted while recognizing that its relationship to the primary change endpoint is not fully specified.

It also highlights the distinction between arm-level estimates and a direct comparison. The two group changes have their own confidence intervals, but uncertainty about the treatment contrast is represented by the interval for the contrast itself. The reported interval, -1.20 to 1.81, includes zero and spans possible differences in either direction. Reporting the direct estimate and its interval is more informative for the comparative question than relying on separate group summaries alone.

The difference between the safety and outcome analysis populations is another important feature. The registry states that 68 participants were included in the safety analysis and 55 had Week 12 assessments for outcome analyses. Missing-outcome reasons and handling methods are not reported, limiting assessment of possible bias from incomplete follow-up.

The study is listed as a Phase 3 randomized, quadruple-masked trial, but its registry status is terminated and its listed enrollment is 70. The brief summary describes two planned parts with different approximate enrollment targets. The record does not explain the relationship between those plans and the enrollment or report the termination reason. For statistical interpretation, these gaps matter: design labels do not replace details about analysis populations, methods, and study conduct. The result is most useful when read with those uncertainties made explicit.

15. Limitations

Several limitations are specific to the information recorded for this trial. The primary outcome is described as a change from baseline, but the reported between-group analysis is labelled as a difference in final values. The analysis method and the relationship between that contrast and the change endpoint are not reported in the registry record. This prevents a full assessment of the estimand and of whether baseline adjustment or another model was used.

The outcome analysis included 55 participants with Week 12 assessments, compared with 68 in the safety analysis. The record does not explain why assessments were unavailable, describe missing-data handling, or provide sensitivity analyses. As a result, the influence of incomplete outcome follow-up cannot be evaluated from the posted information.

The registry names secondary outcomes for function and PGIC, but their numerical results are not reported in the information analyzed. It also does not report a multiplicity strategy, a p-value for the primary comparison, or the statistical analysis plan. The absence of these details limits evaluation of how the primary and secondary findings were intended to be interpreted together.

The brief summary describes a two-part plan, with approximate enrollment targets for each part, while the registry lists enrollment of 70 and status as terminated. The record does not explain how the planned parts relate to the listed enrollment, whether the second part proceeded, or why the study was terminated. No conclusions about the reason or consequences of termination can be drawn from the status alone.

The registry does not report a clinically important difference threshold for WOMAC A, so the practical importance of the observed score estimates cannot be determined from the listed values alone. The masking level is recorded as quadruple, but the masked roles and operational details are not described. These omissions do not negate the reported statistics, but they constrain how confidently the results can be interpreted and generalized beyond the recorded analysis.

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19. Record Summary

The registry describes a Phase 3 randomized, quadruple-masked, parallel-group, placebo-controlled study of FX006 32 mg versus normal saline in patients with hip osteoarthritis. Enrollment is listed as 70; the study status is terminated. The primary endpoint was change from baseline to Week 12 in WOMAC A pain score.

The primary-outcome analysis included 55 participants with Week 12 assessments: 24 in the FX006 group and 31 in the normal saline group. Reported least-squares mean changes were -1.85 and -2.16, respectively. The reported final-value mean difference was 0.31, with a 95% confidence interval from -1.20 to 1.81; no p-value or analysis method is reported.

The safety analysis included 68 participants. Serious adverse events and deaths were reported as zero in both groups. The registry names function and PGIC as secondary outcomes, but their numerical results are not reported in the information analyzed. Reasons for termination, missing outcome assessments, and the statistical plan are not reported in the registry record.

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