An Efficacy Study of Osmotic Release Oral System (OROS) Methylphenidate in Participants With Attention-Deficit/Hyperactivity Disorder (ADHD): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for An Efficacy Study of Osmotic Release Oral System (OROS) Methylphenidate in Participants With Attention-Deficit/Hyperactivity Disorder (ADHD) (NCT01060150), a na phase 4 study. The primary outcome is Korean Version of the Attention-Deficit/Hyperactivity Disorder (ADHD) Rating Scale (K-ARS) Score.

2. Clinical Question

The study's stated purpose was to evaluate efficacy, tolerability, and changes in learning skill after OROS methylphenidate treatment. Its primary endpoint was the Korean Version of the ADHD Rating Scale (K-ARS) score at Week 12. The K-ARS is a symptom-rating measure, while the listed secondary outcomes include attention, response, memory, language, and interference test measures.

Because the study has a single group and no concurrent control, its central statistical question is descriptive: what outcome values were recorded after treatment in the study population? A change over time, if reported, would describe what happened during follow-up in participants receiving the study drug. On its own, such a change cannot separate a treatment effect from other explanations, such as changes over time, expectations in an open-label study, or measurement variability. The primary endpoint result itself is not reported in the registry record, so its direction, magnitude, and precision cannot be assessed from the posted information.

3. Trial Design

This was a Phase 4, multi-center, open-label, single-group study of OROS methylphenidate HCl. The official title describes a 12-week study of efficacy and learning skill in adolescents with ADHD. The registry record lists 115 enrolled participants and marks the study as completed. It gives a start date of 2008-07 and a primary completion date of 2010-04. Janssen Korea, Ltd., Korea is listed as the sponsor.

The design has no randomized allocation and no masking. Allocation is recorded as not applicable, and the trial model is single group. The registry record does not describe a separate untreated, placebo, or active comparator group. Consequently, the study is not a randomized comparison, and its outcomes should not be interpreted as if they were differences between comparable treatment arms. Open-label status also means participants and study personnel were not masked to the treatment.

The intervention is OROS methylphenidate HCl. The record does not report a dose, a dose-adjustment plan, or additional treatment details. Although the official title specifies the intended study duration, the registry record does not give participant-level treatment duration or follow-up completion information. The enrollment figure is the registry's reported enrollment, not a statement that every enrolled participant contributed data to every outcome.

The primary outcome was the K-ARS score at Week 12, described as a mean with standard deviation. The registry defines the intent-to-treat population for that endpoint as participants who received the study drug at least once, met inclusion and exclusion criteria, and had baseline efficacy assessment data. Missing Week 12 values were imputed using last observation carried forward (LOCF). The record does not report the endpoint mean, standard deviation, baseline-to-Week-12 change, or a confidence interval. It also does not report a detailed statistical analysis plan, a sample-size justification, or interim analyses.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat (ITT) population included all participants who received the study drug at least once, satisfied the inclusion and exclusion criteria, and had efficacy assessment data at the Baseline. Missing values at Week 12 were imputed using Last observation carried forward (LOCF).

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 Korean Version of the Attention-Deficit/Hyperactivity Disorder (ADHD) Rating Scale (K-ARS) Score, measured over Week 12.

The primary endpoint is the Korean Version of the ADHD Rating Scale (K-ARS) score at Week 12. The registry describes the K-ARS as a rating scale used for ADHD diagnosis and assessment of treatment efficacy. It comprises 18 items based on the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, with each item rated from 0-3 points. The total score ranges from 0-54, with 0 described as normal and 54 as severe condition.

The endpoint is a continuous measure: its value can vary across a range rather than falling into only a few categories. The registry specifies that the primary result should be represented as a mean and standard deviation. A mean describes the average score in the analyzed population, while the standard deviation describes how spread out individual scores are around that mean. Those statistics answer different questions and should not be treated as interchangeable.

A symptom-rating scale can provide a structured way to describe ADHD-related symptoms at a specified assessment time. The Week 12 timing makes the endpoint a follow-up measurement, but the record does not provide the observed Week 12 score or a baseline score. It therefore cannot establish how scores changed during the study or how much individual participants' scores varied. The endpoint result, including any estimate of precision, is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a continuous score, and the registry specifies a mean and standard deviation as its summary statistics. A mean gives a central summary of observed scores. The standard deviation describes the spread of those scores around the mean. A narrow spread indicates that observations are more clustered around the average; a wider spread indicates greater participant-to-participant variation. Neither statistic alone describes uncertainty in the estimated mean. The registry record does not report these primary endpoint values.

What would a confidence interval add?

General statistical explanation: A confidence interval expresses uncertainty around an estimate under the statistical method used. It is not a range containing a stated proportion of individual participants' scores, and it does not correct limitations in the study design. For a single-group endpoint, an interval around a mean would describe uncertainty in that group's mean under the analysis assumptions. It would not turn the mean into a comparison with an unobserved control group. No confidence interval for the K-ARS endpoint is reported in the registry record.

What does the study design imply?

General statistical explanation: Randomization helps create groups that can be compared by reducing systematic differences at the start of a study. A concurrent comparator also helps distinguish changes associated with treatment from changes that may occur over time for other reasons. This study is recorded as single group, with allocation not applicable and no masking. Its outcomes can be described for the participants studied, but a treatment contrast against a concurrent control is not available. Open-label conduct can also affect reporting or assessment, particularly when outcomes involve ratings or tests influenced by participant or assessor expectations.

What is LOCF?

The registry says missing Week 12 primary endpoint values were imputed using last observation carried forward. In this approach, the last available observation is used in place of a missing later measurement. General statistical explanation: This procedure effectively assumes that the last observed value is an appropriate substitute for the unobserved value at the target time. That assumption may be unrealistic if participants' scores would have changed after their last assessment. LOCF also does not eliminate uncertainty created by missing data; it substitutes values according to a rule. The registry record does not report the amount of missingness, the timing of last observations, or sensitivity analyses using alternative missing-data assumptions.

What is the intent-to-treat population?

The registry's primary endpoint population includes participants who received the study drug at least once, satisfied inclusion and exclusion criteria, and had efficacy assessment data at baseline. This is the record's operational definition for the primary endpoint. It should not be assumed to be identical to every use of the term intent-to-treat: conventions for analysis populations vary, and the registry definition is the relevant one for interpreting this record. The number of participants in that population is not reported in the registry record.

How should multiple outcomes be considered?

The record lists 12 outcome measures and 0 analyses. The secondary outcomes include multiple tests and score components addressing attention, reaction time, response variability, digit span, finger-window performance, verbal fluency, and Stroop performance. When many outcomes are assessed, the chance of obtaining at least one apparently unusual result can increase if each is tested separately. General statistical explanation: Multiplicity can be addressed through prespecified outcome hierarchies, adjusted testing procedures, or careful emphasis on estimation rather than isolated significance tests. The registry record does not report a multiplicity strategy, and it does not provide analysis results for the listed measures. No claim about statistical significance across these outcomes can therefore be made from the record.

Why can over-dispersion matter?

General statistical explanation: Over-dispersion occurs when variability in data is greater than a statistical model assumes. If a model underestimates variability, standard errors can be too small and intervals or tests can appear more precise than warranted. The primary K-ARS endpoint is described with a mean and standard deviation, but the registry does not report a model for it or identify over-dispersion as an issue. This general concept should not be mistaken for a finding about this study.

How do sample-size illustrations differ from trial evidence?

The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of an observed effect. For non-time-to-event calculations, the stated convention is participants per arm; time-to-event calculations are described in terms of total events. General statistical explanation: Such calculations explore how a hypothetical design might perform under chosen assumptions. They are not observed outcomes, evidence that the current study had a particular probability of detecting an effect, or a substitute for a trial's own sample-size rationale. Here, the actual trial is single group, and the registry record does not report a trial-specific sample-size justification or the primary endpoint result from which an observed effect could be interpreted.

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("OROS Methylphenidate HCl")
n   <- c(113)
m   <- c(11.78)
sp  <- c(7.64)
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  OROS Methylphenidate HCl  113  11.780  7.640  10.356  13.204

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 12 outcome measures and 0 analyses. It names secondary outcomes covering ADHD Diagnostic System test errors and response measures, digit span, finger-window performance, verbal fluency, and Stroop outcomes. The presence of these listed outcomes does not establish that each was collected or analyzed. The record does not report outcome-level estimates, uncertainty intervals, or p-values for them.

When investigators examine multiple outcomes or multiple components of a measure, interpreting isolated results can be misleading unless the analysis plan accounts for multiplicity. General statistical explanation: A prespecified primary endpoint can help distinguish the main confirmatory question from exploratory questions, while an explicit testing strategy can address the increased chance of false-positive findings across multiple tests. The registry record does not report a multiplicity adjustment or a hierarchy for interpreting outcomes. With no analysis results reported, there is no basis to assess whether any multiplicity approach was used in practice.

For the primary K-ARS endpoint, the registry specifies an intent-to-treat population and says that missing Week 12 values were imputed using LOCF. It does not report the size of that analysis population, how many Week 12 observations were missing, or how many values were imputed. It also does not provide sensitivity analyses that could show whether conclusions change under alternative assumptions about missing outcomes. Missing-data handling for the secondary outcomes is not reported in the registry record.

The primary endpoint's analyzed result is not reported, so the effect estimate and its precision cannot be evaluated. The record also does not report a statistical analysis plan, interim analyses, or a trial-specific sample-size justification. Their absence from the registry entry should be read as unavailable information, not evidence that a particular procedure was or was not used outside the record.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lymphadenitis (0.9%), appendicitis (0.9%).

The registry reports serious adverse-event figures for the OROS methylphenidate HCl group: 113 participants at risk and 2 affected. For other adverse events, it reports 113 at risk and 98 affected. These are separate registry summaries; they should not be added together or interpreted as a count of distinct participants, since the record does not explain overlap between categories. The registry lists lymphadenitis and appendicitis among the top serious adverse-event terms, each reported as 0.9%.

These figures describe events recorded in the study group. They do not establish that an event was caused by treatment, and the registry record does not report the event terms' relationship to treatment, timing, duration, or clinical course. The event counts also do not provide a comparison with people who did not receive the study drug. With no concurrent control group, they cannot be used to estimate a relative increase or decrease in risk.

The death count is not reported in the registry record. The reported at-risk figures for the event categories should not be assumed to be the denominator for every outcome or every safety analysis unless the record specifies that. The safety summary is therefore useful as a description of recorded events, but it is not a complete account of event severity, exposure time, or causality.

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

The record describes a completed Phase 4 study evaluating OROS methylphenidate HCl in Korean participants with ADHD. It identifies the primary endpoint as the Week 12 K-ARS score and describes how the endpoint was defined and how missing Week 12 values were handled. It also lists learning and cognitive outcomes and provides adverse-event summaries. These details help readers understand the study's intended measurements and the limits of the available registry information.

The primary endpoint result is not reported in the registry record. Without a mean, standard deviation, change estimate, or confidence interval, the posted information does not establish what K-ARS scores were observed at Week 12 or how precisely they were estimated. It is not possible to characterize the size or direction of an endpoint change from the record. The listed outcome measures are not a substitute for their results, and 0 analyses are reported.

The study's single-group, open-label design also limits causal interpretation. A description of outcomes among participants who received the study drug is not equivalent to a randomized estimate of what the treatment changed. There is no concurrent comparator group in the record to distinguish treatment-associated changes from other changes over time or influences related to unmasked assessment. The record therefore cannot support a like-for-like comparison with another treatment or control condition.

The reported serious and other adverse-event figures are descriptive. They do not show whether the events were caused by the study drug, and, without a comparator, they do not quantify a treatment-related difference in risk. The registry does not report a death count or detailed event context. These limitations are separate from the absence of efficacy results: safety counts do not supply the missing primary outcome estimate.

Overall, the registry record supports a description of the study design, endpoint definition, missing-data rule, listed outcomes, and reported safety counts. It does not provide the numerical primary efficacy result needed to assess the endpoint's observed magnitude or precision. It also does not establish a causal treatment effect.

14. Why This Trial Matters Statistically

This study illustrates why a clearly stated endpoint does not, by itself, provide an interpretable efficacy result. The registry specifies a Week 12 K-ARS score, describes the scale and its range, and identifies the population for analysis. Those details establish what the primary outcome was intended to measure. However, without the observed score summary or an estimate of change, readers cannot assess the outcome's magnitude or precision.

It also demonstrates the distinction between a within-group description and a controlled treatment comparison. A single-group study can describe scores and events among participants receiving an intervention. It cannot directly show how those outcomes compare with what would have happened in a concurrent control group. The open-label design further makes it important to consider potential influences on reported or assessed outcomes.

The missing-data rule is another important part of interpretation. LOCF is identified for missing Week 12 primary endpoint values, but the amount of missingness and any sensitivity analysis are not reported. A named imputation method tells readers how missing values were intended to be handled; it does not, on its own, show whether the resulting estimate is robust to assumptions about unobserved values.

Finally, the registry records multiple outcome measures but reports 0 analyses. This distinction reinforces why outcome listings should not be read as evidence of findings. Multiplicity, population definitions, missing-data assumptions, and study design all shape what an analysis can establish. In this case, the registry record contains useful methodological descriptions and safety counts, but not the numerical primary endpoint result or a randomized comparison.

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 most direct limitation for interpreting efficacy is that the registry record does not report the primary K-ARS result. It gives the endpoint definition and the Week 12 assessment time, but no mean, standard deviation, change estimate, or confidence interval. The record therefore does not allow readers to judge the observed outcome or its precision.

The single-group design has no concurrent comparator, and the study is open label. This restricts causal interpretation and leaves no like-for-like control comparison. The record does not report a dose or dosing schedule, so those aspects of the intervention cannot be evaluated from the registry entry. It also does not report participant-level follow-up, treatment adherence, or the number of participants who completed the Week 12 assessment.

The registry defines the primary endpoint population and reports LOCF for missing Week 12 values, but does not state the size of that analysis population, the extent of missingness, or the number of imputed values. Sensitivity analyses are not reported. The record does not report how missing data were handled for secondary outcomes.

Although 12 outcome measures are listed, 0 analyses are reported. There are no outcome-level results for the listed cognitive and learning measures, and no multiplicity strategy is reported. A statistical analysis plan, interim analyses, and a trial-specific sample-size justification are also not reported in the registry record. Safety summaries lack details about event timing, treatment relationship, and overlap between categories; the death count is not reported. These are limitations of the information available in the registry record and do not establish what may have been documented elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: An Efficacy Study of Osmotic Release Oral System (OROS) Methylphenidate in Participants With Attention-Deficit/Hyperactivity Disorder (ADHD) — NCT01060150.
• Registry record last updated 2013-08-23; status last verified 2013-08.
• Results first posted 2013-07-31.
• 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 registry record describes a completed Phase 4, 12-week, multi-center, open-label, single-group study of OROS methylphenidate HCl in Korean participants with ADHD. It lists 115 enrolled participants, with a start date of 2008-07 and primary completion date of 2010-04. The official title identifies adolescents as the study population.

The primary endpoint was the K-ARS score at Week 12, summarized as a mean and standard deviation. The record defines the primary endpoint population and states that missing Week 12 values were handled using LOCF. It lists 12 outcome measures and 0 analyses, but does not report the primary endpoint result or results for the secondary measures.

For the OROS methylphenidate HCl group, the registry reports serious adverse events for 113 at risk and 2 affected, and other adverse events for 113 at risk and 98 affected. Lymphadenitis and appendicitis are each listed as 0.9% among the top serious adverse-event terms. The record does not report a concurrent comparator or a death count.