Study of Cingal® for Symptomatic Relief of Osteoarthritis of Hip Joint: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Cingal® for Symptomatic Relief of Osteoarthritis of Hip Joint (NCT04640298), a na na study. The primary outcome is Numerical Rating Scale (NRS) Pain on Walking.

2. Clinical Question

This is a before-and-after clinical question within a single group, not a question about whether Cingal outperforms a concurrent control. The study’s stated purpose was to obtain clinical data to support an expanded indication for symptomatic relief of hip osteoarthritis. That purpose describes the intended use of the study; it does not establish what the outcome showed. Without a posted primary estimate, its variability, or a comparison group, readers cannot assess the size or precision of any observed change or separate a change over time from other influences.

3. Trial Design

The registry describes a prospective, single-group study of Cingal for symptomatic relief of osteoarthritis of the hip joint. Its listed intervention is a single injection into the hip joint. The study is marked completed, with an enrollment of 25. The recorded phase is NA, allocation is NA, and masking is none. These entries do not describe a randomized, masked, controlled comparison.

The recorded study start is 2021-01-16, and the primary completion date is 2021-09-10. The registry’s brief summary says the trial was intended to obtain clinical data supporting an expanded indication for a single injection of Cingal for hip osteoarthritis. The primary outcome is NRS pain on walking, measured as change from baseline to 6 months after injection. Secondary outcomes listed are the Lequesne Hip Index, Patient Global Assessment score, an OMERACT-OARSI responder measure, and use of rescue medication.

Because only one group is listed, changes in that group can be described, but the design does not supply a concurrent estimate of what would have happened under a different treatment or no study intervention. The record does not report the protocol’s rationale for the design, the sample-size justification, or further procedural details. Completion status and planned outcome timing do not substitute for posted outcome estimates; the primary numerical result is 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: Intent To Treat (ITT)

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: Intent to Treat (ITT)

6. Primary Endpoint

The registry lists the primary outcome as Numerical Rating Scale (NRS) Pain on Walking, measured over 6 months.

The primary endpoint is change in the index hip’s Numerical Rating Scale (NRS) pain-on-walking score from baseline to 6 months after injection. The NRS is described as an 11-point scale, ranging from 0 for no pain to 10 for the worst pain level. Participants reported their pain, and the registry specifies a mean as the summary measure and standard deviation as the dispersion measure. The primary population is identified as Intent To Treat (ITT).

Change scores give a direct description of how a participant’s reported score differs from their baseline score over the stated follow-up interval. Under the registry’s definition, a negative change means less pain after treatment; a more negative change represents a greater improvement. The direction is important when interpreting a mean because a negative value is not a worsening under this convention.

Pain on walking is the trial’s chosen primary symptom measure. A mean can describe the group’s average change, while a standard deviation describes the spread of individual changes around that mean. Neither statistic alone establishes how precise the estimated average is; a confidence interval would help express that uncertainty. The registry record does not report the primary endpoint’s numerical estimate, standard deviation, confidence interval, or participant-level distribution, so the magnitude and precision of the observed change cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean change describe?

For a continuous measure such as an NRS score, a change score expresses the difference between a participant’s follow-up score and baseline score according to the outcome’s defined convention. Averaging those changes gives a group mean change. The registry specifies that the primary measure is the mean change in pain on walking from baseline to 6 months. It also defines the direction: negative values indicate less pain after treatment, and more negative values indicate greater improvement.

A group mean is a compact description, not a description of every participant’s experience. Participants can have changes that differ substantially from the mean. The standard deviation is a measure of the spread of observed values around the mean. A relatively dispersed set of changes can make the group average less representative of any single participant, even though the mean remains a valid summary of the group. The registry identifies standard deviation as the primary endpoint’s dispersion measure, but the numerical value is not reported in the registry record.

How should uncertainty be assessed?

General statistical interpretation distinguishes variability in observations from uncertainty in an estimated average. A standard deviation describes the spread of observations. A confidence interval describes a range of values compatible with the data and the statistical method used, and indicates the precision of an estimate. A narrow interval generally indicates greater precision than a wide interval, although precision does not by itself establish clinical importance or remove limitations of the study design.

The primary result and its precision cannot be evaluated without a numerical estimate and an uncertainty measure. The registry record does not report a confidence interval for the primary endpoint. A p-value, if reported, would address a different question and would not replace the need to see the estimated magnitude and its uncertainty. The primary p-value is not reported in the registry record.

What does the single-group design allow?

The study is listed as a single-group design, with no randomized comparison and no masking. A within-group analysis can describe how scores in the enrolled group differ between baseline and follow-up. It cannot, on its own, estimate how scores would have changed over the same period under a different treatment or without the intervention. Changes can reflect multiple influences, including changes over time and factors associated with measurement or participation. This is a general limitation of interpreting before-and-after findings without a concurrent control.

The registry’s primary population is ITT. In general, an ITT approach seeks to analyze participants in the groups to which they were assigned, regardless of later treatment adherence. In a single-group study, the label still identifies the intended analysis population, but it does not by itself explain how missing outcome measurements were handled, how many participants contributed data at follow-up, or which records were included in the primary calculation. Those details are not reported in the registry record.

What do the planning illustrations mean?

The sample-size material is described as a planning illustration computed from an observed effect, rather than as the trial’s own prospective design. Its stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. These are assumptions for an illustrative planning exercise, not evidence that the single-group study itself was planned as a two-arm trial. They should not be read as the trial’s protocol or as an account of its actual allocation.

Planning sample sizes answer a hypothetical design question: how many participants per arm would be needed under specified assumptions to detect a target effect at a stated power. Such illustrations depend on the effect size and other assumptions used. They are not observed power, do not establish that the completed study had adequate power, and do not replace an outcome estimate with its uncertainty. The registry record does not report the study’s own sample-size justification or statistical plan.

When an outcome is more variable than a planning model assumes, a study may have less precision than expected for a fixed sample size. More generally, assumptions about the distribution of an outcome matter because the calculation’s operating characteristics depend on how well the assumed model represents the data. This is a general point about planning; the registry record does not report a distributional assessment or a plan for handling over-dispersion for this endpoint.

What other analysis details matter?

The record identifies five outcome measures and three analyses, but detailed analysis specifications are not reported in the registry record. It does not describe the exact statistical test or model used for the primary endpoint, any adjustment variables, how repeated measurements were handled, or the confidence-interval method. The outcome description identifies a baseline-to-follow-up change and the mean as the parameter, but that is not enough to reconstruct the complete analysis.

Recalculation from summary statistics, when possible, would be an unadjusted calculation and may not reproduce a sponsor’s analysis if that analysis uses a different model or data handling. No recalculated primary estimate is available in the registry record. Accordingly, there is no basis for comparing an independent recalculation with a sponsor analysis, or for making a claim about which result takes precedence.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Cingal")
n   <- c(25)
m   <- c(-2.48)
sp  <- c(1.61)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Cingal  25  -2.480  1.610  -3.145  -1.815

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies five outcome measures and three analyses. It lists the Lequesne Hip Index, Patient Global Assessment score, the OMERACT-OARSI responder measure, and rescue-medication use among the secondary outcomes. The NRS pain-on-walking change is the primary outcome. The record does not report how the analyses map to the listed outcomes or whether any outcomes had multiple time points or analysis variants.

When a study evaluates several outcomes or conducts multiple statistical tests, the chance of finding at least one apparently notable result can increase. A prespecified multiplicity strategy can address that issue, for example by defining a primary outcome and controlling how secondary tests are interpreted. This is a general statistical consideration; the registry record does not report a multiplicity adjustment or a hierarchy for interpreting the secondary outcomes. Their numerical results are not reported in the registry record.

The primary population is identified as ITT, but the record does not describe missing-data handling. It does not state how missing baseline or follow-up scores were treated, whether any imputation was used, or how participants with incomplete measurements contributed to analyses. The number with outcome data at each assessment and the reasons for missing data are also not reported in the registry record. Without these details, the effect of missing observations on the estimate cannot be assessed.

The registry record does not report the statistical analysis plan, interim analyses, or sensitivity analyses. These omissions do not show that such procedures were or were not used; they mean that the record does not document them. The absence of these details limits assessment of whether the analysis choices were prespecified and how robust the findings were to alternative assumptions.

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 1% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists 25 participants at risk for serious adverse events and records 0 serious adverse events. It also lists 25 at risk for other adverse events, with 4 in the other-adverse-event count, and records 0 deaths. These are the counts entered in the registry; the record does not provide further detail that would establish the nature, timing, severity, or attribution of the other adverse events.

The absence of a recorded serious adverse event in this study does not establish that the intervention has no serious risks. Safety counts from a study need to be interpreted in light of how events were defined and collected, the observation period, and the amount of information available. The registry does not report the safety follow-up window or detailed event-collection methods. Specific serious adverse-event terms are not reported in the registry record.

These figures are descriptive safety entries, not a comparison of event rates between treatments: only one study group is listed. The counts also do not establish whether an event was caused by the intervention. No causal attribution should be inferred from the counts alone.

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

The record describes a completed prospective study of a single Cingal injection for hip osteoarthritis, identifies pain on walking as the primary outcome, and specifies how change is interpreted. It also records safety counts. These details show what the study was intended to assess and what categories of results were registered.

The primary numerical result is not reported in the registry record. Readers therefore cannot determine from the posted results whether the mean NRS pain-on-walking score changed, in which direction it changed, how large any change was, or how precise an estimate might be. The outcome definition explains that a negative change would indicate less pain, but it is not itself evidence that the score decreased.

The design also limits what a change could establish. A single-group before-and-after assessment can describe changes in the enrolled group, but without a concurrent comparator it cannot distinguish the intervention’s contribution from other influences on scores over time. The record does not describe random allocation or masking; allocation is recorded as NA and masking as none. No like-for-like controlled comparison is available in the listed design.

The secondary outcomes and safety entries do not resolve these limitations. Their numerical results and detailed analysis methods are not reported in the registry record. The safety counts do not measure pain change, and they do not provide a comparison with another treatment. The study’s stated aim of supporting an expanded indication should not be mistaken for a result or a conclusion about efficacy.

Overall, the record supports a description of the design, the intended primary measure, and the recorded adverse-event counts. It does not support a quantitative conclusion about the primary outcome’s magnitude or precision, nor a comparative conclusion about treatment effects. Those judgments require posted outcome estimates and, for a comparative claim, an appropriate comparison.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of why design and outcome reporting must be read together. The primary question concerns change in a continuous pain score over time, and the registry supplies a clear direction convention for that change. Yet a defined endpoint cannot answer the clinical question without its numerical result. The missing mean change and uncertainty measure prevent assessment of magnitude and precision.

The single-group design makes the distinction between descriptive change and comparative effect especially important. A baseline-to-follow-up change can characterize what happened in the observed group, but it does not by itself show what would have happened under another condition. The registry record identifies no randomized comparator and no masking. Interpretation must therefore remain within the limits of a one-group assessment rather than treating the study as a controlled efficacy comparison.

The record also illustrates why outcome variability and precision are different considerations. The mean would summarize average change; the standard deviation would describe variation among observations; and a confidence interval would convey uncertainty around the estimated mean. Although the registry identifies the intended mean and standard deviation summaries, their values and a confidence interval are not reported. Neither the sample enrollment nor the endpoint definition can substitute for these results.

Finally, the listed planning assumptions should be separated from the actual study design. The planning illustration uses a hypothetical two-arm framework, while the registered study is single-group. Such illustrations can help frame future planning only when their assumptions are understood; they do not establish observed power or provide evidence of a treatment effect. The statistical importance of this record lies as much in these interpretive boundaries as in the outcomes it set out to measure.

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.

Several limitations are specific to the information recorded for this study. The single-group design has no concurrent control, and the registry identifies no random allocation or masking. Any within-group change would therefore be difficult to separate from other influences over time. The enrollment is 25, but the registry does not report the sample-size justification, so the enrollment alone does not establish the intended precision or adequacy of the study for a particular effect.

The primary endpoint is described, but its numerical result is not reported in the registry record. The record also does not report its standard deviation, confidence interval, or participant-level distribution. Without those quantities, readers cannot assess the size or precision of the change, or whether the mean adequately represents the range of individual outcomes.

The record names ITT as the primary population but does not explain how missing outcome data were handled or how many participants contributed data at follow-up. It does not report analysis specifications, multiplicity procedures, or sensitivity analyses. These gaps limit reproducibility and make it difficult to judge whether alternative reasonable analysis choices would affect interpretation.

Although the primary outcome has a 6-month timeframe, the safety follow-up window is not reported in the registry record. The adverse-event entries do not include detailed event descriptions or attribution. The record’s listed secondary measures are not accompanied by numerical results in the information available, so they cannot provide corroboration or context for the unreported primary estimate.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of Cingal® for Symptomatic Relief of Osteoarthritis of Hip Joint — NCT04640298.
• Registry record last updated 2024-12-16; status last verified 2024-12.
• Results first posted 2024-03-07.
• 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

NCT04640298 is a completed prospective, single-group study of a single Cingal injection for symptomatic hip osteoarthritis. The registry lists an enrollment of 25, no masking, and allocation recorded as NA. The recorded study start is 2021-01-16, and the primary completion date is 2021-09-10.

The primary outcome is mean change from baseline to 6 months in index-hip NRS pain on walking, with negative change defined as less pain after treatment. The registry identifies ITT as the primary population. Numerical primary and secondary outcome results are not reported in the registry record. Safety entries record 0 serious adverse events, 4 in the other-adverse-event count, and 0 deaths.

The record describes study intent and outcome definitions but does not provide a controlled comparison or enough primary outcome data to assess the size and precision of change.