OA Clinic-Community CARE Model: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for OA Clinic-Community CARE Model (NCT05349500), a randomized na study. The primary outcome is Change From Baseline to Month 6 in Western Ontario and McMasters Universities Osteoarthritis (WOMAC) Total Score.

2. Clinical Question

3. Trial Design

OA Clinic-Community CARE Model, also called OA CARE, is a randomized, single-masked, parallel-group behavioral trial. The registry lists an enrollment of 60 and a status of completed. The trial began on 2022-06-07, and primary completion was recorded as 2024-02-08. The phase is listed as NA. The sponsor is the University of North Carolina, Chapel Hill.

The trial compared an OA CARE intervention with a usual-care control group. The intervention sought to connect clinical and community services, coordinating patient programs with primary-care-provider involvement. Its described components include a YMCA medical membership for 12 months, a 12-week weight-loss program, exercise and weight-management support, and tailored referrals. The primary-care-provider component included a video-based summary of treatment guidelines, collaboration on referrals, and progress reports on enrolled patients. Usual-care participants were described as receiving no additional study treatment for about 12 months.

The primary endpoint was change from baseline to month 6 in WOMAC total score. The outcome population is specifically described as participants completing both baseline and six-month assessments. Secondary outcomes listed in the registry include WOMAC pain and function at month 6 and month 12, objectively assessed physical activity, and steps per day. The registry lists 20 outcome measures and 20 analyses, and reports 18 posted secondary outcomes. Details of sequence generation, allocation concealment, the masking procedure, and the precise analysis population for the between-group model 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

Analysis population for the primary outcome, as defined in the registry: Participants who completed both baseline and 6-month follow-up assessments

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.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline to Month 6 in Western Ontario and McMasters Universities Osteoarthritis (WOMAC) Total Score, measured over Baseline, Month 6 (Follow-up).

The primary endpoint was change from baseline to month 6 in the Western Ontario and McMasters Universities Osteoarthritis (WOMAC) total score. WOMAC is a patient-reported measure combining pain, stiffness, and physical-function subscales. The registry describes questions scored on a 0-4 scale, with possible ranges of 0-20 for pain, 0-8 for stiffness, and 0-68 for physical function. The total score ranges from 0-96; higher scores indicate worse pain, stiffness, and functional limitations.

Change over time is useful because it describes how the measured symptom and function burden shifts from a participant’s baseline assessment to follow-up. The comparison between randomized groups then asks whether their average changes differ, rather than treating a follow-up score in isolation. WOMAC is relevant to this trial because the intervention was designed for people with knee or hip osteoarthritis and targeted care components related to symptoms and physical activity. The endpoint does not, by itself, identify which part of a multi-component intervention might account for a group difference. The registry does not report a threshold for interpreting a change as clinically important.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary measure is continuous: WOMAC total score is recorded on a numerical scale, and the posted arm summaries use means. A mean describes the central level of a set of values by averaging observations. For a change endpoint, each participant’s follow-up score is considered relative to baseline, and the arm-level mean summarizes those changes. In this trial, the registry reports mean changes at month 6 for participants completing both baseline and follow-up assessments.

What does the confidence interval express?

A confidence interval represents the statistical uncertainty around an estimate under the analysis assumptions. It is not a range containing every participant’s result, nor does it state that there is a particular probability that the fixed true effect lies inside the observed interval. Repeated use of the same interval procedure under its assumptions would produce intervals covering the true parameter at the stated confidence level at the specified rate. The arm summaries have 95% confidence intervals, as does the sponsor’s between-group estimate.

The OA CARE arm’s mean change is -7.8, with a 95% confidence interval from -16.04 to 0.4. The usual-care arm’s mean change is 3.2, with a 95% confidence interval from -4.8 to 11.2. The sponsor’s model-based contrast is -11.0, with a 95% confidence interval from -20.1 to -1.9. These intervals are not interchangeable: the first two concern the mean change in each arm; the latter concerns the comparison between arms under the sponsor’s model.

How should the p-value be read?

The sponsor reports p = 0.019 for the mixed-model comparison. In general, a p-value measures how unusual data at least as incompatible with a specified null hypothesis would be, if that null hypothesis and the statistical model were correct. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. Here, the p-value accompanies an estimated difference and its confidence interval; it should be read alongside both rather than as a stand-alone conclusion.

The registry labels the reported analysis as a superiority comparison and identifies its method as mixed models analysis. Mixed models are generally used to analyze data with grouping or repeated measurements, accounting for correlations that arise when observations are related. The registry does not give the model formula, covariance structure, adjustment variables, or detailed estimation procedure. Those specifics are therefore not reported in the registry record, and should not be inferred from the method label alone.

Why can the group contrast differ from the arm summaries?

A between-group estimate is not simply a restatement of either arm’s mean change. It compares groups and may be based on a model that handles the outcome data differently from a pair of separately reported means. The registry’s reported analysis describes its parameter as a mean difference in final values, while the primary endpoint is titled as change from baseline to month 6. The record does not explain this wording in more detail. Accordingly, the sponsor’s model-based contrast should be identified using the analysis description the registry supplies, rather than recast as a different estimand.

In general, estimates can have different precision depending on the amount of information, variability, correlation between repeated measurements, and model specification. If data are more variable than a model assumes, standard errors and confidence intervals may be understated; this general concern is often described as over-dispersion in settings where it applies. The registry does not report an over-dispersion assessment for this continuous endpoint, and there is no basis to claim that over-dispersion affected this analysis.

The registry also lists 20 outcome measures and 20 analyses, with 18 secondary outcomes posted. When many outcomes or comparisons are examined, the chance of finding at least one apparently notable result can increase if no multiplicity strategy is used. Whether adjustment or a prespecified hierarchy was used is not reported in the registry record. The primary result should therefore be distinguished from the additional outcome results, and the record does not establish how multiplicity was addressed.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s own primary comparison as a mixed-model analysis, with a mean difference in final values of -11.0, a 95% confidence interval from -20.1 to -1.9, and p = 0.019. The arm-level summaries report mean changes of -7.8 for OA CARE and 3.2 for usual care. These quantities have different descriptions in the registry: the arm results are mean changes, while the sponsor’s parameter is labeled a difference in final values. They should not be treated as identical estimates.

No discrepancy is flagged between the posted values and the sponsor’s analysis. The registry record does not report a separate recalculated contrast. The sponsor’s reported model-based result is therefore the relevant stated inferential analysis; it should not be replaced by an unadjusted calculation from arm summaries. Details needed to independently reproduce the mixed model, including its formula and handling of missing observations, are not reported in the registry record.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 20 outcome measures and 20 analyses, and 18 secondary outcomes are posted. The secondary outcomes include WOMAC pain and function at month 6 and month 12, as well as activity and step-count measures. Examining multiple outcomes raises a general statistical issue: the more hypotheses tested, the greater the opportunity for one or more results to appear notable by chance. This does not show that a particular reported result is false; it means the interpretation depends partly on how analyses were planned and whether multiplicity was considered.

A prespecified primary outcome can help focus interpretation, but the registry record does not report a multiplicity adjustment, testing hierarchy, or other strategy for controlling error across outcomes. It also does not report whether interim analyses were conducted or whether a statistical analysis plan specified how secondary findings would be interpreted. Those details should not be assumed.

The stated primary outcome population consists of participants who completed both baseline and month-6 assessments. The registry does not report the number of participants with missing outcome data, reasons for missingness, imputation methods, sensitivity analyses, or whether the sponsor’s model used all available observations. It does not describe an intention-to-treat analysis population or another population definition for the reported model. Although the record lists an enrollment of 60 and arm-specific outcome counts of 24 and 27, those entries alone do not explain participant flow or the handling of missing data. The analysis population and missing-data assumptions remain uncertain from the registry record.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The adverse-event record lists 30 participants at risk for serious adverse events in each arm, with zero serious adverse events affecting participants in OA CARE and zero in usual care. It also lists 30 at risk for other adverse events in each arm, with zero affected in either group. No top serious-event terms are listed. These figures describe what the registry reports; they do not establish that no unrecorded or unreported events occurred.

The registry lists one death in the OA CARE group and zero in the usual-care group. Deaths are presented separately from the serious-adverse-event counts in the record, so the zero serious-event figures should not be read as meaning that there were no deaths. The record does not give further detail about the death, its timing, or its relationship to the intervention. The adverse-event entries are descriptive and do not, on their own, establish a cause or comparative safety effect.

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

The posted primary result indicates that the sponsor’s mixed model estimated a lower WOMAC score for OA CARE relative to usual care at the primary assessment, with a mean difference of -11.0 and a 95% confidence interval from -20.1 to -1.9. The arm-level mean changes were -7.8 for OA CARE and 3.2 for usual care. Because higher WOMAC scores indicate worse pain, stiffness, and functional limitations, the direction of the model estimate corresponds to a lower score in the OA CARE group. The reported p-value was 0.019.

This is a group-level statistical result, not a prediction for any individual participant. A confidence interval communicates uncertainty in the estimated contrast, and its range does not establish the exact effect. The registry does not report a threshold for clinical importance, so the result cannot be classified from this record alone as meeting a clinically meaningful-change criterion. Nor does a difference in the combined score identify whether pain, stiffness, or function contributed most to the result.

The intervention was multi-component, pairing patient programs with provider support and tailored referrals. The primary comparison cannot isolate the contribution of any single component. It also does not establish that the same estimate would apply in other settings or populations. The registry record provides limited detail about missing data, the precise model specification, and multiplicity handling, all of which are relevant to judging robustness.

The result does not establish that every participant improved, that all secondary outcomes followed the same pattern, or that no adverse events occurred. The safety record lists zero serious and other adverse events affecting participants in both groups, while separately listing one death in OA CARE and none in usual care. These entries should be read as registry-reported counts, not as proof of causation or as medical advice.

14. Why This Trial Matters Statistically

This trial is statistically informative because it evaluates a coordinated care model rather than a single isolated treatment. The intervention links clinical guidance and primary-care-provider participation with community-based exercise and weight-management services and tailored referrals. That structure makes it important to distinguish the effect of assignment to the overall model from the effect of any one component. The primary comparison addresses the package as a whole.

The endpoint also illustrates why the estimand and model description matter. The primary outcome is framed as change from baseline, while the sponsor analysis is described as a mixed-model difference in final values. A careful reading keeps those labels distinct and avoids assuming details about adjustment or repeated-measure handling that the registry does not state. The arm summaries and the sponsor’s contrast answer related, but not identical, descriptive questions.

The record reports both an effect estimate and uncertainty, rather than relying only on a significance test. The confidence interval gives context for the plausible range under the model, while the p-value addresses compatibility with a null comparison under specified assumptions. At the same time, the listed outcomes and analyses raise questions about multiplicity, and the registry does not describe how those questions were handled. Missing-data procedures and the full analysis population are also not reported.

These features make the record useful for statistical interpretation while defining its limits. It gives a clear primary endpoint, arm-level summaries, and a sponsor-reported comparison, but it does not provide all the design and analysis details needed for independent reconstruction. Reading the estimate together with its uncertainty and the reporting gaps is more informative than treating a single p-value as a complete account.

15. 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 registry record gives a concise description of the intervention and comparison but does not provide full operational detail for every component. The OA CARE arm description is incomplete after its reference to navigator work with the primary care provider, and the exact referral and service uptake patterns are not reported. It is therefore not possible to determine from the record how consistently participants received each component or how much exposure varied.

For the primary analysis, the record names mixed models but does not report the model formula, covariates, covariance structure, or detailed missing-data approach. The arm-specific outcome counts are reported as 24 for OA CARE and 27 for usual care, while the overall enrollment is listed as 60. Participant flow and reasons that the analysis counts differ from enrollment are not reported in the registry record. The primary outcome population is defined by completion of baseline and six-month assessments, but the treatment of participants without both assessments is not specified.

The registry lists multiple outcome measures and analyses but does not report whether multiplicity was controlled, whether the primary outcome was part of a prespecified hierarchy, or whether interim analyses occurred. It also does not report a clinically important threshold for WOMAC total-score change. The sponsor’s model estimate is reported as a difference in final values, whereas the endpoint title describes change from baseline; further explanation of this distinction is not reported.

Finally, the adverse-event record gives counts but limited context. It lists one death in OA CARE and none in usual care, without details on timing or relationship to the intervention. These reporting limitations restrict how confidently the estimate, safety entries, and broader applicability can be assessed from the registry record alone.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: OA Clinic-Community CARE Model — NCT05349500.
• Registry record last updated 2025-01-14; status last verified 2023-01.
• Results first posted 2025-01-14.
• 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.

19. Record Summary

OA Clinic-Community CARE Model was a completed, randomized, single-masked, parallel-group behavioral trial sponsored by the University of North Carolina, Chapel Hill. The registry lists an enrollment of 60, a start date of 2022-06-07, and primary completion on 2024-02-08. It compared OA CARE, a clinic-community care package, with usual care.

The primary endpoint was change from baseline to month 6 in WOMAC total score among participants completing both assessments. Reported mean changes were -7.8 for OA CARE and 3.2 for usual care. The sponsor’s mixed-model analysis reported a mean difference in final values of -11.0, with a 95% confidence interval from -20.1 to -1.9 and p = 0.019. The record also lists 18 posted secondary outcomes. Missing-data procedures, full model details, and multiplicity handling are not reported in the registry record.