Clinical Evaluation of Ropinirole IR (Immediate Release) Tablets in Patients Who Are Diagnosed With Symptomatic Restless Legs Syndrome (RLS) Associated With Chronic Kidney Disease (CKD) Managed With Haemodialysis (Including Haemofiltration and Haemodiafiltration): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of Ropinirole IR (Immediate Release) Tablets in Patients Who Are Diagnosed With Symptomatic Restless Legs Syndrome (RLS) Associated With Chronic Kidney Disease (CKD) Managed With Haemodialysis (Including Haemofiltration and Haemodiafiltration) (NCT00996944), a randomized phase 2 study. The primary outcome is International Restless Legs Syndrome (IRLS) Rating Scale Total Score at Week 0 and Week 12.

2. Clinical Question

3. Trial Design

This was a randomized, triple-masked, parallel-group Phase 2 study with a placebo comparator. The registry lists an enrollment of 34 participants. It describes a multicenter comparison of oral ropinirole immediate-release tablets with placebo in people with symptomatic restless legs syndrome associated with chronic kidney disease managed with haemodialysis, including haemofiltration and haemodiafiltration.

The brief summary says the study was intended to evaluate efficacy and safety during a 12-week treatment period. It also describes objectives concerning long-term administration and steady-state pharmacokinetics during long-term treatment. The registry record does not report the detailed sequence or duration of those longer-term procedures, nor does it give arm-specific treatment schedules. The study status is terminated. A reason for termination is not reported in the registry record, so the status alone cannot explain why the study stopped or whether termination altered its planned analyses.

The primary outcome was the IRLS Rating Scale total score at Week 0 and Week 12, reported as a mean with standard deviation. The description states that 17 participants were prematurely withdrawn before Week 12. This matters because incomplete follow-up can affect which data contribute to a Week 12 comparison and how missing measurements are handled. The record does not provide the group-specific number of withdrawals or the analysis method used for missing Week 12 scores.

Randomization and masking are design features intended to limit systematic differences in treatment allocation and expectations. The record calls the study triple-masked but does not identify which roles were masked or how masking was maintained. Details of randomization procedures, allocation concealment, protocol deviations and the statistical analysis plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Double-blind Treatment Period

Reasons for not completing this period:

Long-term Treatment Period

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full Analysis Set (FAS): participants who were progressed to the treatment phase, but excluding those who did not have the target indication, those who had not received at least one dose of the investigational product, and those who did not have any measured efficacy data after initiation of the study 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 International Restless Legs Syndrome (IRLS) Rating Scale Total Score at Week 0 and Week 12, measured over Week 0 and Week 12.

The primary endpoint was the International Restless Legs Syndrome Rating Scale total score at Week 0 and Week 12. The scale is investigator-rated and contains 10 questions, each with five response options scored from 0, the least severe response, to 4, the most severe response. The total is the sum of the response scores, ranges from 0 to 40, and is intended to represent overall restless legs syndrome severity. A score of 40 represents the most severe RLS, while 0 represents an absence of RLS.

Repeated measurement at baseline and follow-up can describe how scores change over the treatment period and can support a comparison between randomized groups. A between-group comparison is generally more informative about a treatment contrast than looking at change in one group alone, because both groups may change over time for reasons unrelated to the assigned treatment. That is a general statistical principle, not a reported analysis result for this trial.

The registry specifies a mean and standard deviation as the summary measures. The mean describes the average score, while the standard deviation describes variation among participants. The posted record does not report the group means, the amount of change, or a between-group estimate. Consequently, the endpoint definition is available, but its observed results and comparative interpretation are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation communicate?

The registry describes the primary endpoint as a mean with standard deviation. In general, a mean is an average that gives a compact description of the values in a group. A standard deviation describes how dispersed participant scores are around that average. Neither quantity alone gives the treatment effect. For a randomized comparison, the central estimate is typically a contrast between groups, such as a difference in average scores or a difference in average change, with an interval describing uncertainty. The registry record does not report such a contrast for the primary endpoint.

The IRLS score is a sum of responses to 10 questions, with response scores from 0 to 4 and total scores from 0 to 40. A mean is useful for describing an overall group level, but a group average can conceal differences in individual experiences. The distribution of scores and the way the analysis handles the bounded scale would help readers understand how representative the mean is. Those distributional details and the primary results are not reported in the registry record.

Why does a confidence interval matter?

In general, a confidence interval expresses the range of estimates reasonably compatible with the observed data under the analysis method. Its width conveys precision: a narrower interval indicates more precision than a wider interval, given the same method and scale. The interval also helps distinguish an estimate near no difference from one that is compatible with a range of potentially meaningful contrasts. It does not guarantee that the true effect lies within a particular interval, and it does not correct for bias caused by missing data, deviations from the analysis plan or other design problems. No confidence interval for the primary comparison is reported in the registry record.

A significance test addresses a different question from estimation. A test result alone does not convey the size of a contrast or how precisely it was estimated. Because the registry record does not report a primary test result or an effect estimate, neither statistical significance nor the practical magnitude of the primary comparison can be assessed from the recorded outcome information.

How should the randomized comparison be understood?

Random allocation is intended to make treatment groups comparable at the point of assignment, on average, including with respect to characteristics that may not have been measured. In general, preserving participants in their assigned groups for analysis helps maintain the protection offered by randomization. The registry identifies the primary population as a Full Analysis Set, but its description is truncated. It says the population excludes people who did not have the target indication, had not received at least one dose, or had no measured efficacy data after treatment began. The precise implementation and analysis population counts are not reported in the registry record.

The study is described as parallel-group, so treatment groups are compared over the same general study period rather than each participant necessarily serving as their own comparator. The record states that masking was triple, but does not identify the masked parties. In general, masking can reduce the influence of treatment expectations on care, assessment and reporting. It does not eliminate the possibility of missing observations, protocol deviations or measurement error.

Why are withdrawals relevant to the analysis?

The record reports 17 premature withdrawals before Week 12. Missing outcomes can reduce the information available and can introduce bias if the chance of missing a score is related to the score that would have been observed. General missing-data methods make assumptions about those unobserved values; different assumptions can lead to different estimates. A complete-case analysis, for example, uses only participants with recorded outcomes, while other approaches may use additional observed information under specified assumptions. The registry record does not identify which method was used, whether sensitivity analyses were conducted, or whether withdrawals differed by group.

Baseline and follow-up values can be analyzed in more than one way, including comparison of follow-up scores with adjustment for baseline or comparison of changes from baseline. These methods have different assumptions and can yield estimates with different precision. The primary outcome title names measurements at Week 0 and Week 12, but the analysis approach is not reported in the registry record. It would therefore be inappropriate to infer how baseline scores entered the model or how repeated measurements were handled.

What can be inferred from the available analysis information?

The record lists 19 outcome measures and no analyses. That indicates that outcome definitions are listed without corresponding analysis results in the registry record. It does not establish that no analyses were performed outside the registry. The statistical plan, model specification, treatment of protocol deviations, handling of multiple outcomes, and any interim analyses are not reported in the registry record.

The record contains a general description of assumptions for planning illustrations based on an observed effect, but it does not report a primary effect estimate from which a trial-specific planning illustration could be interpreted. Such illustrations, when available, are planning calculations rather than observed power or evidence that the trial was adequately or inadequately sized. No sample-size justification or prespecified target effect is reported in the registry record. The enrollment of 34 is a recorded enrollment figure, not by itself evidence about precision, power or the adequacy of the design.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 19 outcome measures, including the primary IRLS total score and secondary measures concerning clinical global impression, quality of life and sleep quality. When a study evaluates multiple outcomes, time points, subgroups or analysis choices, the chance of at least one apparently notable result can increase if no multiplicity strategy is used. General approaches include identifying a single primary comparison in advance, adjusting for multiple tests, or treating secondary findings as exploratory. The multiplicity strategy for this trial is not reported in the registry record.

The primary measure is specified at Week 0 and Week 12, but the record does not state whether the primary analysis focused on follow-up score, change from baseline, or another contrast. It also does not report a hierarchy among secondary outcomes or any correction for multiple comparisons. With no outcome estimates or test results posted, it is not possible to assess how multiplicity affected interpretation.

Missing data are a separate concern. The record states that 17 participants were prematurely withdrawn before Week 12. It does not provide the reasons, the treatment-group distribution of withdrawals, or whether these participants had partial follow-up measurements. The method for handling missing values and any sensitivity analyses are not reported in the registry record. General statistical practice treats assumptions about missing outcomes as part of the interpretation, because results can depend on whether missingness is related to observed or unobserved scores.

The stated Full Analysis Set exclusions are described in the primary outcome information, but the full definition is truncated and group-specific analysis counts are not reported in the registry record. The protocol-defined analysis populations, per-protocol analyses and safety population are not described in enough detail to establish how participants were included in each result.

11. 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: atrial flutter (8.3%), upper respiratory tract infection (8.3%), acute coronary syndrome (4.5%).

The registry lists two treatment-group labels for adverse events: Ropinirole IR-Ropinirole IR and Placebo-Ropinirole IR. For the first label, 22 participants were at risk for serious adverse events and 1 was affected; 22 were at risk for other adverse events and 16 were affected. For the second label, 12 participants were at risk for serious adverse events and 1 was affected; 12 were at risk for other adverse events and 10 were affected. These are counts recorded for the listed groups, not estimates of a causal treatment effect. The registry does not explain the treatment sequences represented by the labels.

The record lists atrial flutter and upper respiratory tract infection at 8.3% each, and acute coronary syndrome at 4.5%, among the serious adverse-event terms. The denominators and event-level details for these percentages are not reported in the registry record. These percentages should therefore be read as the registry’s listed frequencies, not recalculated or treated as a complete account of safety.

Deaths are not reported in the registry record. This is different from evidence that no deaths occurred. Counts do not convey event timing, duration, severity beyond the serious-event classification, or whether investigators considered an event related to treatment. The record also does not provide a comparative statistical analysis of adverse events. Because the trial was terminated and the available safety information is limited, these figures describe recorded events but cannot alone establish the relative safety of the treatments.

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

The registry record establishes that a randomized, triple-masked, parallel-group Phase 2 comparison of ropinirole IR and placebo was conducted in people with restless legs syndrome associated with chronic kidney disease managed with haemodialysis. It identifies the IRLS total score at Week 0 and Week 12 as the primary outcome and describes the scale’s scoring. It also records that 17 participants were prematurely withdrawn before Week 12 and lists adverse-event counts for the named groups.

Those details do not answer whether the groups differed on the primary outcome. The registry record does not report group-level IRLS results, an estimated treatment contrast, a confidence interval or a test result. Without these, neither the direction nor magnitude of any difference can be stated, and its precision cannot be evaluated. The absence of a reported result is not evidence of no difference, just as the study’s terminated status does not establish why it ended or what the results would have been.

The safety counts are descriptive. They show recorded numbers of participants affected in the listed groups, but do not include enough detail to assess event timing, attribution, or a comparative safety effect. The serious-event percentages are reported without the denominators needed to interpret their precision. Deaths are not reported in the registry record, which should not be taken to mean that none occurred.

More generally, trial results require attention to the population analyzed, missing data, outcome selection and uncertainty, as well as the design. Here, the record’s incomplete analysis reporting limits what can be concluded. The trial information can be used to understand the intended comparison and some recorded safety information, but not to claim that ropinirole did or did not change symptoms, quality of life or sleep outcomes.

13. Why This Trial Matters Statistically

This trial is statistically notable because its registry record describes a randomized comparison in a specifically defined clinical setting: restless legs syndrome associated with chronic kidney disease managed with haemodialysis, including haemofiltration and haemodiafiltration. Its parallel-group, placebo-controlled structure gives the intended framework for a treatment comparison, while the triple-masked designation indicates an effort to limit knowledge of assignment. These design features matter, but they do not substitute for reported outcome estimates.

The selected primary measure is a continuous total score derived from 10 investigator-rated questions. Its defined range, from 0 to 40, makes score interpretation explicit. Reporting both a mean and standard deviation is useful for describing group summaries, but a treatment comparison also needs an estimated contrast and an indication of uncertainty. Those primary results are not reported in the registry record, making this a clear example of the distinction between a defined endpoint and an interpretable result.

Follow-up is another important statistical feature. The record reports 17 premature withdrawals before Week 12, while not giving group-specific counts, reasons or a missing-data method. That combination illustrates why attrition should be considered alongside the endpoint and the analysis population. The registry also lists 19 outcomes, but does not report the multiplicity approach or the results for those measures.

The study is marked terminated, yet the reason is not reported in the registry record. Termination is a status, not an explanation or a result. Overall, the available information helps readers identify the design and key reporting gaps without treating absent estimates as evidence for either benefit or no effect.

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 most important trial-specific limitation for statistical interpretation is that primary outcome results are not reported in the registry record. There are no arm-level IRLS means or standard deviations, no estimated comparison, and no confidence interval or test result. Therefore, the size, direction and precision of the primary treatment contrast cannot be assessed.

The record reports that 17 participants were prematurely withdrawn before Week 12, but does not describe withdrawal reasons or their distribution across groups. It does not identify the method used to handle missing Week 12 scores or report sensitivity analyses. This limits assessment of whether missing outcomes could have affected the primary comparison.

The Full Analysis Set description is incomplete in the registry record. The stated exclusions identify some eligibility and data requirements, but analysis counts and the exact implementation are not reported. Details of randomization, masking roles, treatment schedules and the analysis plan are also not reported. The registry lists 19 outcome measures but does not describe a multiplicity strategy or provide analyses for them.

The study is marked terminated, and the reason for termination is not reported in the registry record. The record also does not report a sample-size justification, target effect, interim-analysis plan or a detailed account of long-term treatment and pharmacokinetic results. The listed adverse-event counts and serious-event terms are descriptive, with limited information about event timing, attribution and percentage denominators. These reporting gaps constrain interpretation; they do not, by themselves, establish the direction or quality of the trial’s findings.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Evaluation of Ropinirole IR (Immediate Release) Tablets in Patients Who Are Diagnosed With Symptomatic Restless Legs Syndrome (RLS) Associated With Chronic Kidney Disease (CKD) Managed With Haemodialysis (Including Haemofiltration and Haemodiafiltration) — NCT00996944.
• Registry record last updated 2018-08-10; status last verified 2018-06.
• Results first posted 2011-06-13.
• 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

NCT00996944 is a randomized, triple-masked, parallel-group Phase 2 trial comparing oral ropinirole IR with placebo in people with symptomatic restless legs syndrome associated with chronic kidney disease managed with haemodialysis. The registry lists enrollment of 34 and marks the study terminated. The primary outcome was the IRLS Rating Scale total score at Week 0 and Week 12, summarized as a mean and standard deviation. The outcome description reports 17 premature withdrawals before Week 12.

The registry lists 19 outcome measures and no analyses. Primary outcome estimates and the reason for termination are not reported in the registry record. Safety information includes serious and other adverse-event counts for two named groups, while deaths are not reported in the registry record. The listed information describes the study’s design and selected recorded events but does not permit an assessment of the primary treatment effect.