Real-World Outcome of Rheumatoid Arthritis Patients in Korea on Adalimumab: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Real-World Outcome of Rheumatoid Arthritis Patients in Korea on Adalimumab (NCT02627924), a registered phase not stated study. The primary outcome is Change From Baseline in Health Assessment Questionnaire - Disability Index (HAQ-DI) Score at Week 24.

2. Clinical Question

The study focused on patient-reported health-related quality of life and work productivity in rheumatoid arthritis. Its primary endpoint was the change in HAQ-DI score at week 24. Secondary outcomes covered other measures of function, health status, treatment satisfaction, work impact, and use of healthcare resources. This breadth reflects the study’s interest in outcomes experienced by patients and in aspects of daily and clinical life beyond a single disease measure.

Because this was a prospective observational study, it describes outcomes among people receiving treatment in routine clinical practice rather than a randomized comparison of treatment strategies. The record does not report a separate control group suitable for a like-for-like comparison. Therefore, the central question is about change observed in the defined adalimumab-treated population, not whether adalimumab caused that change relative to an alternative.

3. Trial Design

The ROCKA Study was a prospective, observational study of adalimumab use among people with rheumatoid arthritis in Korea. The registry lists enrollment of 91 participants. The study began on 2015-11-18, reached primary completion on 2017-12-28, and has completed status. AbbVie is listed as the sponsor.

Participants were prescribed adalimumab according to their physician’s discretion and routine clinical practice. This means the treatment decision was part of clinical care rather than assignment by a stated trial randomization procedure. The registry does not state an allocation method. It also does not describe a like-for-like control arm, so the record does not support interpreting the study as a controlled treatment comparison.

The primary endpoint was change from baseline in HAQ-DI score at week 24. The specified endpoint population included participants who were still receiving adalimumab at week 24 and had HAQ-DI data at both baseline and week 24. This population definition is important: it does not automatically describe every enrolled participant, and the registry record does not give the number meeting those criteria.

Secondary outcomes included HAQ-DI change at week 12 and clinically meaningful HAQ-DI improvement at weeks 12 and 24. Other listed outcomes were SF-36 physical and mental component scores, EQ-5D-3L index, and WPAI, each assessed for change at weeks 12 and 24. Treatment satisfaction and healthcare resource use were also included, specifically visits to healthcare professionals and procedures related to rheumatoid arthritis treatment. The record lists 12 outcome measures and 12 analyses. It does not provide the numerical primary endpoint result or enough detail to reconstruct the study’s complete statistical analysis plan.

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 were still receiving adalimumab at week 24 and with available HAQ-DI data at baseline and week 24.

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 enrolled participants

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Health Assessment Questionnaire - Disability Index (HAQ-DI) Score at Week 24, measured over Baseline and week 24.

The primary endpoint was change from baseline in the Health Assessment Questionnaire–Disability Index (HAQ-DI) score at week 24. HAQ-DI is a patient-reported measure of physical function. Its questions cover activities such as dressing and grooming, arising, eating, walking, hygiene, reaching, gripping, and common daily activities. Participants report how difficult these tasks were during the past week.

The scale ranges from 0, representing the best score, to 3, representing the worst. Higher scores indicate greater dependency due to disability. A change from baseline is used to describe whether the average measured function in the endpoint population moved over the follow-up period. The registry specifies the mean as the summary measure and standard deviation as the measure of dispersion.

HAQ-DI is relevant to a study concerned with quality of life because it captures perceived difficulty with everyday function rather than only a clinical or laboratory measure. It provides a structured way to summarize participants’ reports across several activity domains. The endpoint’s interpretation nevertheless depends on the observed change, its variability, and the number of participants with data at both time points.

The numerical mean change, standard deviation, and associated uncertainty for this endpoint are not reported in the registry record. The endpoint population is defined as those still receiving adalimumab at week 24 with available HAQ-DI data at baseline and week 24; the record does not state how many participants met that definition.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies the primary outcome as a continuous measure summarized by its mean, with standard deviation used to describe dispersion. These summaries answer different questions. The mean indicates the central average change in HAQ-DI for the analyzed participants. The standard deviation describes how much participants’ measured changes vary around that average. Neither statistic, by itself, establishes why scores changed.

What does a change score represent?

A change score compares a participant’s measurement at follow-up with that participant’s baseline measurement. Summarizing those individual changes with a mean gives an average within-person change for the analysis population. This is distinct from comparing separate groups at follow-up. For this study, the primary time point was week 24, and the endpoint population required HAQ-DI measurements at both baseline and week 24 while still receiving adalimumab at week 24.

Change scores can be useful because each participant serves as their own reference for describing movement over time. But a before-and-after summary does not provide the counterfactual outcome: what would have happened to those same participants over the same period without the treatment. That comparison generally requires an appropriate control design or other defensible causal method. The registry describes no like-for-like control comparison.

Why report a standard deviation?

General statistical explanation: the mean compresses a set of observations into one central summary, while the standard deviation gives a sense of their spread. A small spread means observations tend to lie closer to the mean; a larger spread means observations are more dispersed. The standard deviation is not the same as the uncertainty in the estimated mean. Precision of an estimate is commonly conveyed using a confidence interval or another inferential measure, but such a result is not reported for the primary endpoint in the registry record.

For a continuous outcome, the mean is often an interpretable summary when the distribution and analysis assumptions make it appropriate. If outcomes are strongly skewed or contain unusual values, the mean can be influenced by those observations. The registry record does not report distributional checks, transformations, robust methods, or an alternative summary for the primary endpoint. Those methods therefore cannot be attributed to this study.

What does an observational design change?

In an observational study, clinicians’ decisions and participants’ circumstances shape who receives the treatment. Here, adalimumab was prescribed according to physician discretion and routine clinical practice. This may make the setting relevant to routine care, but it also means the treated population was not described as randomized. Differences in health, treatment history, or other factors could be associated both with treatment decisions and with outcomes. A simple change over time cannot distinguish treatment effects from such influences or from changes that might occur with time and usual care.

Randomization, when used, helps balance measured and unmeasured factors between groups on average. Since the record does not describe a randomized comparison or a suitable control group, the primary endpoint should be read as an outcome in the defined treated population, not as a treatment effect relative to another strategy. The record does not report an adjusted causal analysis that would alter this interpretation.

How should planning illustrations be understood?

General statistical explanation: sample-size planning asks how many participants a future study might need under specified assumptions about the effect to detect, the significance level, allocation, and statistical model. A planning illustration is conditional on those assumptions; it is not an observed result and not a measure of the probability that a completed study’s finding is correct. The registry’s planning description states a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect.

The record does not say that these planning assumptions were the original design justification for this observational study. The record also does not report a randomized two-arm comparison, so an equal-allocation illustration should not be mistaken for the study’s actual treatment assignment. Sample-size calculations are planning scenarios, never observed power. Where the sponsor’s own analysis differs from a simple recalculation, the sponsor’s analysis takes precedence.

No inferential model, confidence-interval method, adjustment strategy, or detailed statistical analysis plan for the primary endpoint is reported in the registry record. The numerical endpoint result is also not reported there. Accordingly, a reader cannot verify model assumptions or independently assess the endpoint estimate’s precision from this record.

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("Adalimumab")
n   <- c(71)
m   <- c(-0.67)
sp  <- c(0.67)
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  Adalimumab  71  -0.670  0.670  -0.829  -0.511

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures and 12 analyses. The primary outcome is HAQ-DI change at week 24; the listed secondary outcomes cover additional time points and other patient-reported, work-related, satisfaction, and healthcare-use measures. When many outcomes or time points are examined, the chance of obtaining at least one apparently notable result can increase. Statistical methods may address this through a prespecified hierarchy, adjustment, or a clear distinction between confirmatory and exploratory analyses.

The registry record does not report whether a multiplicity adjustment was used, how outcomes were ordered for formal testing, or whether any secondary outcomes were designated as exploratory. It also does not report a detailed statistical analysis plan. Without that information and the numerical results, the strength of evidence across multiple measures cannot be assessed.

Missing-data handling is also not reported in the registry record. The primary endpoint population requires continued adalimumab use at week 24 and available HAQ-DI data at baseline and week 24. The record does not state the number of participants with both measurements, the reasons for missing data, whether missing values were imputed, or whether sensitivity analyses were performed. These details matter because a complete-case result can differ from the result that would be obtained if all enrolled participants’ outcomes were available.

The registry specifies an outcome population but does not describe a broader analysis population or an intention-to-treat approach. Since the study is observational and treatment was prescribed in routine clinical practice, the analysis-population rules and treatment discontinuation handling would be useful for understanding who contributed to each result. Those procedures are not reported in 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: arthralgia (1.1%), arthritis (1.1%), intervertebral disc protrusion (1.1%), spinal column stenosis (1.1%), pneumonia bacterial (1.1%).

The registry lists 91 participants at risk in the adalimumab group for both serious and other adverse-event reporting. It records 6 participants affected by serious adverse events and 6 affected by other adverse events. These are separate registry fields and should not be added together: the record does not establish that the groups are mutually exclusive. The listed number of deaths is 0.

The serious adverse-event terms listed are arthralgia, arthritis, intervertebral disc protrusion, spinal column stenosis, bacterial pneumonia, and deep vein thrombosis. Each listed term is shown at 1.1%. These entries describe the registry’s reported terms and percentages; they do not provide enough detail to infer event timing, duration, severity beyond the serious classification, relationship to treatment, or clinical course.

Adverse-event counts are descriptive. In an observational study without a like-for-like control comparison, these figures alone cannot establish whether events were caused by treatment or compare risk with another treatment strategy. They also do not provide a complete account of individual-level overlap between event categories. The registry record does not report additional safety detail needed to make those assessments.

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

The study addresses an important measurement question: how physical function, quality of life, work productivity, treatment satisfaction, and healthcare use were assessed among people with rheumatoid arthritis receiving adalimumab in Korean routine practice. Its prospective observational design and defined week-24 HAQ-DI endpoint describe the intended approach and outcome population.

The record does not report the numerical result for the primary outcome or the listed secondary outcomes. Therefore, it does not support a conclusion about the size or direction of change in HAQ-DI, how precisely that change was estimated, or whether other measures moved consistently. Outcome definitions and planned time points should not be mistaken for observed findings.

Even with a reported before-and-after change, the design would not by itself establish that treatment caused the change. There is no like-for-like control comparison described, and treatment was prescribed according to physicians’ discretion and routine practice. The observed course could reflect treatment, other care, natural changes over time, or participant characteristics. The registry record does not provide an analysis that separates these influences.

The safety entries report serious and other adverse-event counts, a list of serious-event terms and their percentages, and no deaths. These descriptions are informative as registry reporting but do not establish causation or comparative safety. They should be interpreted alongside the observational design and the limits of the reported detail.

In short, the registry documents the study’s question, design, outcome definitions, and selected safety counts, but not the numerical outcome results needed to judge the magnitude or precision of observed changes. It therefore supports a description of what was assessed, rather than a quantitative conclusion about the primary endpoint or a causal comparison.

14. Why This Trial Matters Statistically

Clinical studies often measure more than disease activity. Physical function, health-related quality of life, work impact, satisfaction, and healthcare use can describe different dimensions of participants’ experience. ROCKA’s listed outcomes reflect that broader measurement perspective, with HAQ-DI change selected as the primary endpoint.

The study is also statistically instructive because its design and endpoint population need to be kept distinct. A prospective observational assessment can document outcomes over time in routine practice, while a causal treatment comparison requires a credible counterfactual. The registry describes physician-directed prescribing and no suitable control comparison, so changes in the treated population cannot be read as effects relative to an alternative.

The primary endpoint’s restriction to participants still receiving adalimumab at week 24 and with HAQ-DI data at baseline and week 24 is another important interpretive point. Results from such a population would answer a question about those meeting the endpoint criteria. They would not necessarily represent all enrolled participants, especially when the size of that analysis population and the handling of missing data are not reported.

Finally, the distinction between a planned outcome and a posted result is essential. The registry describes the measures and follow-up points, but does not report numerical results for the primary or secondary outcomes. Without estimates and uncertainty measures, statistical interpretation is limited even when the design and endpoint are clearly described. This reinforces why outcome definitions, analysis populations, missing-data procedures, and result reporting all matter when evaluating clinical evidence.

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 principal limitation for interpreting efficacy-related outcomes is that numerical primary and secondary results are not reported in the registry record. The primary endpoint is clearly defined, but its mean change, standard deviation, and estimate of uncertainty are unavailable. The direction, magnitude, and precision of the observed change therefore cannot be assessed from the record.

The observational design limits causal interpretation. Adalimumab was prescribed at physicians’ discretion in routine clinical practice, and the registry does not describe a suitable control group or allocation method. This leaves potential differences among treated participants and other influences on change over time unresolved. A within-person comparison from baseline to follow-up cannot, by itself, isolate a treatment effect.

The endpoint population includes participants who remained on treatment at week 24 and had HAQ-DI data at both time points. The record does not report how many participants met these criteria, why measurements may have been missing, or how missingness was addressed. It also does not report whether participants who discontinued treatment were included in any other analysis.

The statistical analysis plan is not reported in enough detail to assess model choice, adjustment for potential confounding, multiplicity handling, or sensitivity analyses. Although the registry lists 12 outcome measures and 12 analyses, it does not state how the outcomes were prioritized for inference. The planning description is not a substitute for an original sample-size justification, which is not reported in the registry record.

Safety reporting is limited to the listed counts, serious-event terms and percentages, and deaths. The record does not provide the detail needed to assess timing, event duration, treatment relationship, or category overlap. These limitations constrain the conclusions that can be drawn from the registry entry.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Real-World Outcome of Rheumatoid Arthritis Patients in Korea on Adalimumab — NCT02627924.
• Registry record last updated 2019-03-22; status last verified 2018-11.
• Results first posted 2019-03-22.
• 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

The ROCKA Study was a completed prospective observational study sponsored by AbbVie, evaluating adalimumab use among people with rheumatoid arthritis in Korea. The registry lists enrollment of 91 participants, a start date of 2015-11-18, and primary completion on 2017-12-28. Treatment was prescribed according to physician discretion and routine clinical practice.

The primary endpoint was change in HAQ-DI score from baseline to week 24 among participants still receiving adalimumab at week 24 with data at both time points. Secondary outcomes covered function, health status, work impairment, treatment satisfaction, and healthcare resource use. The registry record does not report numerical primary or secondary outcome results or detailed statistical procedures for missing data and multiplicity.

For safety, the record lists 6 participants affected by serious adverse events, 6 by other adverse events, and 0 deaths among 91 at risk. It lists six serious-event terms, each at 1.1%. These observational safety figures do not establish treatment causation or comparative risk.