Osteoarthritis Shoulder Injection Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Osteoarthritis Shoulder Injection Study (NCT03586687), a randomized phase 4 study. The primary outcome is Change in Overall SPADI Scores at Baseline Compared to 2,4, and 6 Months..

2. Clinical Question

The clinical question is about comparing assigned steroid concentrations, rather than establishing whether an injection is better than no injection. Random allocation can support a fair comparison of groups when assignment is maintained and the analysis follows the trial plan, but details of the allocation procedure and analysis are not reported in the registry record. The three arms differ in triamcinolone concentration; each description also includes lidocaine. The registry record does not report whether other aspects of care were standardized or whether participants could receive subsequent treatment during follow-up. It notes that differences in the number analyzed across arms were due to the need for subsequent treatment. That detail matters because later treatment can affect the interpretation of observed score changes and the set of participants contributing outcome data.

3. Trial Design

NCT03586687, titled Osteoarthritis Shoulder Injection Study, is a Phase 4, randomized, triple-masked, parallel-group trial sponsored by Milton S. Hershey Medical Center. The registry record lists Glenohumeral Osteoarthritis as the condition and Triamcinolone as the drug intervention. The study began on 2018-07-13, and its primary completion date is 2021-09-28. Its status is terminated. Enrollment was 19.

Participants were assigned among three dose groups: 20 mg, 40 mg, or 80 mg of triamcinolone. Each arm description includes 3cc of 1% lidocaine. The study description says the injections were ultrasound guided. Triple masking means the registry classifies the trial as masked at three roles or levels, but the identities of those masked and the practical masking procedures are not reported in the registry record. The method used to generate the random sequence, conceal assignments, or maintain masking is also not reported in the registry record.

The design is parallel: the intended comparison is between groups assigned to different concentrations, rather than a crossover in which the same participants receive each concentration in sequence. The primary outcome is change in overall SPADI score, assessed at baseline and follow-up time points of 2, 4, and 6 months. The registry record also names secondary outcomes concerning the rate of shoulder arthroplasty following injection and change in overall SPADI scores for those receiving shoulder arthroplasty at 1 Year.

Termination status alone does not explain why the trial ended or whether the reason was related to safety, recruitment, logistics, or another consideration. The reason for termination, the target enrollment, and any planned sample-size justification are not reported in the registry record. The registry record reports 4 outcome measures, but a complete account of how each was analyzed is not reported. It lists no statistical analyses. Consequently, the design features identify the intended comparison, but they do not establish what analyses were completed or what conclusions the investigators reached.

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: Difference in subjects analyzed for all arms was due to the need of subsequent treatment

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 in Overall SPADI Scores at Baseline Compared to 2,4, and 6 Months., measured over baseline, 2, 4, and 6 months. Baseline SPADI score was collected prior to injection..

The primary endpoint is change in overall SPADI scores at baseline compared with 2, 4, and 6 months. SPADI is a 13 item assessment of current shoulder pain and disability. Its scores range from 0-100, with higher scores indicating greater impairment or disability. The endpoint therefore expresses symptoms and functional difficulty using a patient-reported measure, rather than an imaging measure or a count of clinical events.

Change from baseline is used to describe how scores vary over follow-up relative to each participant’s starting score. Comparing changes across randomized dose groups addresses whether the average course of reported pain and disability differs by assigned concentration. The registry record specifies the outcome as a mean and its dispersion as a standard deviation. These summaries would describe the group average and the spread of individual scores, but the actual means, standard deviations, and changes are not reported in the registry record.

Repeated assessments can show whether group patterns are similar or diverge over time. They also create an analysis question: whether each time point is treated separately, modeled jointly, or handled using another prespecified approach. The analysis method and any clinically meaningful threshold for interpreting score change are not reported in the registry record. Thus, the endpoint definition identifies what was intended to be measured, but does not establish the magnitude, precision, or clinical importance of any observed difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

For a continuous measure such as SPADI, the mean is the arithmetic average of participants’ scores or changes. The standard deviation describes how dispersed individual values are around that average. Together, they provide a compact description of the group, but they do not show every participant’s experience or the shape of the distribution. A mean change can conceal substantial variation: some participants may have improved, some may have changed little, and others may have worsened. The registry record names the mean and standard deviation as the intended summary, but the values themselves are not reported in the registry record.

Group averages are not themselves a comparison. To address the randomized dose question, an analysis would ordinarily estimate a contrast between groups, such as a difference in average change, and report uncertainty around that contrast. The contrast’s direction indicates which group had the higher or lower score change under the chosen coding, while its magnitude describes the estimated separation. Because higher SPADI scores indicate greater impairment or disability, interpretation also depends on whether the analysis defines change as follow-up minus baseline or baseline minus follow-up. That sign convention is not reported in the registry record.

How should uncertainty be understood?

A confidence interval is a range of values compatible with the data and statistical model under the method’s assumptions. It communicates precision: a narrow interval indicates more precision than a wide interval. The interval is not a guarantee that the true effect lies inside it, and its interpretation depends on the sampling and modeling framework. For dose comparisons, the interval is especially useful because it can show whether the data are consistent with both small and large differences, even when a single p-value is available. No confidence intervals for the primary endpoint are reported in the registry record.

A p-value describes how surprising data at least as extreme as those observed would be under a specified null model and its assumptions. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. Statistical significance alone cannot show whether an estimated score difference matters to patients. Conversely, a non-significant result does not establish that the groups are equivalent. The registry record lists no p-values or statistical analyses for the primary outcome.

Why does the three-arm structure matter?

There are three randomized concentrations, so there are several possible pairwise comparisons and more than one follow-up time point. If each comparison is tested independently, the chance of at least one false-positive finding across a family of tests can increase. A statistical plan can address this through a prespecified primary contrast, an adjustment for multiple testing, or another approach. The choice depends on the study question. The registry record does not report a multiplicity strategy, a prioritized comparison, or which time point would anchor a primary inference.

Repeated measurements from the same participant are related: a person’s scores over time are not independent observations. An analysis that treats every measurement as unrelated can misstate uncertainty. A model for repeated measures can account for within-participant correlation and use the pattern across follow-up, while separate time-point analyses answer narrower questions. These approaches can differ in assumptions and in how incomplete follow-up is handled. The analysis model and correlation structure are not reported in the registry record.

Why can over-dispersion and small groups matter?

For outcomes that are counts, over-dispersion means the observed variation is greater than a simple model expects. A model that ignores extra variation may produce confidence intervals that are too narrow and p-values that overstate evidence. The primary endpoint is continuous, not a count outcome, so over-dispersion is not the central issue for its mean-and-standard-deviation summary. Still, unusual distributions, outliers, or unequal variability can affect the suitability of a simple mean-based model. Distributional checks and model diagnostics are not reported in the registry record.

With enrollment of 19 split across three groups, estimates can be imprecise and sensitive to the observations available for analysis. Small samples also limit the ability to detect imbalance in baseline characteristics and make complex models difficult to support. These are general statistical concerns, not evidence that a particular bias occurred in this trial. The actual group-specific outcome counts and estimates are not reported in the registry record, so the precision of any treatment comparison cannot be evaluated.

What do the planning illustrations mean?

A sample-size calculation is a planning exercise that asks how many participants might be needed under assumptions about the target effect, variability, significance level, allocation, and analysis. The stated assumptions for the planning illustration are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. This is an illustration based on an observed effect, not the trial’s own design justification, and it should not be described as observed power. The registry record does not report the trial’s own sample-size justification.

The assumptions describe a two-arm planning comparison even though the trial randomized participants among three dose groups. They should not be mistaken for a statement that the actual trial used equal allocation between two groups or that the investigators planned around the observed effect. The numeric planning outputs and the observed effect used to generate them are not reported in the registry record. Planning calculations also do not repair limited enrollment, missing outcome data, or uncertainty about the analysis actually performed. Their value is conditional on the assumptions being suitable for the question and on the underlying effect estimate being meaningful.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is measured at baseline and at 2, 4, and 6 months, with three randomized dose groups. This creates multiple possible comparisons across both dose pairs and follow-up times. If several hypotheses are tested without a plan, the overall chance of a false-positive result can rise. A prespecified primary contrast, a hierarchy of outcomes, or a multiplicity adjustment can clarify how evidence should be judged. The registry record does not report which approach, if any, was planned or used. It also does not identify one follow-up time as the sole basis for a primary comparison.

The registry record notes that the difference in subjects analyzed for all arms was due to the need for subsequent treatment. It does not report group-specific analyzed counts for SPADI at each follow-up, the number of missing scores, reasons for missingness, or the method used to handle missing data. It is therefore not possible to determine whether the analysis used all randomized participants, only participants with available measurements, or another population. The intended analysis population and any sensitivity analyses are not reported in the registry record.

Subsequent treatment can complicate interpretation because later care may affect follow-up scores and may influence whether a participant remains available for measurement. A trial can define its main estimand around assignment regardless of later treatment, or use a different approach, but the choice needs to be explicit. The record does not report how later treatment was incorporated into the primary analysis. It also does not report the statistical analysis plan, the handling of protocol deviations, or whether any interim analyses were conducted. No interim analysis plan is reported in the registry record.

Without these details, readers cannot judge the extent to which incomplete follow-up, repeated testing, or post-randomization events affected the reported inference. Since no outcome analyses are listed, there is no posted primary result to evaluate for robustness across analysis populations or missing-data assumptions.

11. 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.

Most frequent non-serious adverse event terms

The registry record reports serious adverse events among participants at risk as follows: 0 among 6 in the 20 mg group, 0 among 9 in the 40 mg group, and 0 among 4 in the 80 mg group. Deaths were 0 in all three groups. Other adverse events were recorded as 1 among 6 participants in the 20 mg group, 2 among 9 in the 40 mg group, and 0 among 4 in the 80 mg group. These are counts, not comparative estimates adjusted for follow-up or other factors.

Zero recorded serious events means none were reported among the participants counted as at risk in these groups; it does not establish that the risk is zero. The group sizes are small, so the counts provide limited information about uncommon events. The registry record does not report definitions of serious or other adverse events, how events were collected, their timing, or whether the observation period was the same across groups. It also does not report a statistical comparison of safety between doses.

The other-event counts should likewise be read as descriptive. Without event types, severity, duration, and exposure time, they do not show whether events were related to the injection or differed meaningfully by dose. These figures describe the posted safety record and cannot establish a dose-specific safety profile.

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

The registry record establishes that a randomized, triple-masked, parallel-group study compared three triamcinolone concentrations in people with glenohumeral osteoarthritis. Its stated primary question concerned change in SPADI, a measure of current shoulder pain and disability, over follow-up. The record also gives enrollment, study status, and adverse-event counts. These registry entries describe the intended comparison and the posted information; they do not provide an estimate of how scores changed in any group.

The primary outcome results are not reported in the registry record. There is no basis in the posted record to say which dose had a larger or smaller mean change, whether differences were statistically distinguishable, or how precise a comparison might be. The study hypothesis of equivalent improvement with the low dose remains a hypothesis in the absence of an equivalence margin, a suitable analysis, and reported results. No treatment-effect conclusion should be drawn from the absence of posted analyses.

Similarly, the listed adverse-event counts are observations in small groups, not proof that events are absent or that one concentration is safer. The record does not provide enough detail to assess event definitions, observation time, or comparative safety uncertainty. Termination status is reported, but the reason for termination is not reported in the registry record; status alone should not be interpreted as evidence about efficacy or safety.

The study can still be informative as a record of a dose-comparison question and its planned patient-reported endpoint. To evaluate the clinical findings, readers would need group-specific results, uncertainty estimates, analysis methods, counts at each follow-up, and an account of later treatment and missing data. Without these, the registry record cannot establish whether the observed differences were clinically meaningful, whether the dose groups were equivalent, or how broadly the findings would apply.

13. Why This Trial Matters Statistically

This trial addresses a statistical problem that often arises in dose-finding comparisons: a study may be framed around whether lower exposure can produce outcomes similar to higher exposure, rather than simply asking whether any group differs from another. Those questions require different interpretations. Evidence of no detected difference is not interchangeable with evidence of equivalence. A well-defined equivalence question requires a margin set in advance, a suitable analysis, and estimates precise enough to exclude differences outside that margin. The margin and analysis are not reported in the registry record.

The design also raises the challenge of interpreting several concentrations across repeated measurements. Comparing three arms at multiple time points can produce many plausible contrasts. Without a declared testing strategy, selective emphasis on one comparison or time point can overstate the strength of evidence. A clear plan helps readers distinguish the main question from exploratory comparisons. Such a plan is not reported in the registry record.

The endpoint is patient-reported and measured repeatedly, so the analysis must account for related observations from the same participant and for incomplete follow-up. The registry notes that differences in the numbers analyzed across arms were due to subsequent treatment, making the handling of post-randomization events particularly relevant. Yet the analysis population and missing-data methods are not reported. This illustrates why reporting participant flow and analysis choices is essential alongside an endpoint definition.

Finally, the enrollment of 19 across three dose groups underscores the importance of precision, not just whether a test crosses a threshold. Small groups may leave wide uncertainty and limited capacity to distinguish modest effects or uncommon harms. Because the primary results are absent, the precision cannot be assessed. The statistical importance of the record lies in the questions it makes visible: dose comparison, equivalence, repeated measures, multiplicity, later treatment, and transparent reporting of uncertainty.

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 of the registry record for statistical interpretation is that it contains no primary outcome estimates and lists no statistical analyses. The mean SPADI scores, changes, standard deviations, between-group contrasts, confidence intervals, and p-values are not reported in the registry record. This prevents assessment of effect direction, magnitude, precision, or statistical evidence.

Enrollment was 19, and the registry notes that the number of subjects analyzed differed across arms because of the need for subsequent treatment. Group-specific analyzed counts, follow-up completion, reasons for missing scores, and the handling of subsequent treatment are not reported. Without these details, the degree of missingness and its possible influence on the comparison cannot be evaluated.

The record describes a hypothesis of equivalent improvement, but does not report an equivalence margin or an analysis plan designed to test equivalence. The multiplicity strategy for the three groups and repeated follow-up assessments is not reported. The protocol’s sample-size justification, target enrollment, and interim analysis plan are also not reported in the registry record. The planning assumptions described for an illustration do not establish what the investigators planned for this trial.

Generalizability is difficult to assess because eligibility criteria, participant characteristics, and recruitment details are not reported in the registry record. Masking is classified as triple, but the roles masked and the procedures used to maintain masking are not reported. The reason for termination is not reported in the registry record. These gaps do not prove a flaw in trial conduct, but they limit the conclusions that can be drawn from the registry information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Osteoarthritis Shoulder Injection Study — NCT03586687.
• Registry record last updated 2022-03-02; status last verified 2022-02.
• Results first posted 2022-03-02.
• 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.

18. Record Summary

NCT03586687 is a Phase 4, randomized, triple-masked, parallel-group study sponsored by Milton S. Hershey Medical Center. It enrolled 19 participants and compared intraarticular triamcinolone doses of 20 mg, 40 mg, and 80 mg, with 3cc of 1% lidocaine described in each arm. The study began on 2018-07-13, had a primary completion date of 2021-09-28, and is listed as terminated.

The primary outcome was change in overall SPADI scores from baseline to 2, 4, and 6 months. SPADI is a 13 item measure with scores from 0-100; higher scores indicate greater impairment or disability. The registry record lists secondary outcomes concerning shoulder arthroplasty and SPADI among participants receiving arthroplasty. Primary outcome estimates and statistical analyses are not reported in the registry record.

Serious adverse events and deaths were recorded as 0 in each dose group. Other adverse-event counts were 1 in the 20 mg group, 2 in the 40 mg group, and 0 in the 80 mg group. The registry record does not report the reason for termination, the primary analysis methods, or enough detail to assess outcome precision or comparative safety.