This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Vimpat® Added as Adjunctive Therapy to One Baseline Antiepileptic Drug (NCT01098162), a registered phase not stated study. The primary outcome is Clinical Global Impression of Change (CGI-C) at Month 6.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01098162 |
| Phase | Phase not stated |
| Condition | Epilepsies, Partial |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 576 |
| Arms in the primary outcome | n/a |
| Lead sponsor | UCB Pharma GmbH |
| Results posted | Yes |
2. Clinical Question
Population
People with partial-onset seizures, with or without secondary generalization, receiving care in daily clinical practice in Germany. The study focused on patients taking one baseline antiepileptic drug. The record gives an enrollment of 576. It describes a Full Analysis Set of 520 subjects and says 515 subjects were included in the analysis of the primary outcome.
Intervention
Vimpat® added to one baseline antiepileptic drug as routine treatment in accordance with the local marketing authorization. The study was non-interventional: the record describes the treatment being observed in clinical practice, not an assigned treatment regimen.
Comparator
No separate comparator group is described. The record does not state how treatment allocation occurred, and this is not a randomized comparison. The baseline assessment is a reference for describing change, not a concurrent control group.
Primary question
At Month 6, how did investigators rate each subject’s clinical status compared with baseline, using the Clinical Global Impression of Change? The registry record describes the categories but does not report how many subjects fell into each category or the results of a statistical comparison.
The study aimed to collect seizure-control and tolerability information prospectively in routine practice. Its secondary outcomes cover changes in frequencies of partial-onset seizures without secondary generalization and seizures with secondary generalization at Month 3 and Month 6, as well as adverse events during the study. These are descriptive questions about experience during treatment. Without a concurrent control group, changes over time cannot by themselves separate treatment-associated change from other explanations, such as the course of epilepsy or changes in care.
3. Trial Design
This was a completed, non-interventional post-marketing study sponsored by UCB Pharma GmbH. The record gives a start of 2010-03 and a primary completion of 2013-07. It describes routine clinical practice in Germany and Vimpat® added to one baseline antiepileptic drug, with treatment in accordance with local marketing authorization. The record does not describe a protocol-mandated treatment assignment or a randomized allocation process.
The enrollment is recorded as 576. The primary outcome description says that the Full Analysis Set comprised 520 subjects and that 515 subjects were included in the analysis of that outcome. These figures refer to different recorded populations. The registry record does not explain the reasons for the difference or give a complete participant flow, so the counts should not be used to infer why subjects were not included in the primary-outcome analysis.
The primary outcome was investigator-rated Clinical Global Impression of Change at Month 6. The listed secondary outcomes cover seizure-frequency changes at Month 3 and Month 6 for seizures with and without secondary generalization, and adverse-event incidence during the study. The record lists 6 outcome measures, but it does not provide outcome-category counts or estimates for the primary endpoint in the registry record for this account.
The registry record lists 0 analyses. That entry does not supply a statistical analysis plan, nor does it explain how the primary endpoint or the secondary outcomes were analyzed. Details such as adjustment for baseline characteristics, handling of repeated measurements, and methods for missing data are not reported in the registry record. The single treatment description and the stated absence of a randomized comparison mean that any observed changes should be read as within-study observations, not as estimates from a like-for-like controlled treatment comparison.
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.
Before assignment: Participant Flow refers to the Enrolled Set (ES). The ES comprises all subjects who have been included in the observational study and for whom baseline examination data are available. Three patients were removed from the Enrolled Set after discussion in the Data Review Meeting.
Overall Study
| Stage | Vimpat® |
|---|---|
| STARTED | 573 |
| COMPLETED | 461 |
| NOT COMPLETED | 112 |
Reasons for not completing this period:
| Reason | Vimpat® |
|---|---|
| Adverse Event | 37 |
| Lack of Efficacy | 4 |
| Wish of Patient | 7 |
| Lost to Follow-up | 9 |
| Lack of Efficacy & Wish of Patient | 5 |
| Adverse Event & Lack of Efficacy | 6 |
| Adverse Event & Wish of Patient | 13 |
| Adverse Event & Lost to Follow-up | 2 |
| AE & Lack of Efficacy & Wish of Patient | 1 |
| Wish of Patient & Lost to Follow-up | 1 |
| Other Reason | 1 |
| Reason Unknown | 26 |
Analysis population for the primary outcome, as defined in the registry: Of the 520 subjects in the Full Analysis Set (FAS), 515 subjects are included in the analysis of this outcome measure. FAS comprises all subjects who have been treated with Vimpat® at least once, who fulfill the inclusion criteria and for whom a valid baseline and post-baseline value of seizure frequency is available.
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: Baseline characteristics refer to the Full Analysis Set (FAS) which comprises all patients who have been treated with Vimpat® at least once and for whom a valid value of seizure frequency is available.
| Characteristic | Unit | Vimpat® |
|---|---|---|
| Participants analysed | 520 | |
| Age, Continuous | years | 47.1 (SD 17.0) |
| Age, Customized: < 16 years | participants | 0 |
| Age, Customized: >= 16 years to <= 18 years | participants | 7 |
| Age, Customized: > 18 years to <= 64 years | participants | 419 |
| Age, Customized: >= 65 years | participants | 94 |
| Sex: Female, Male: Female | Participants | 264 |
| Sex: Female, Male: Male | Participants | 256 |
| Race/Ethnicity, Customized: North/Middle European | participants | 484 |
| Race/Ethnicity, Customized: South European | participants | 28 |
| Race/Ethnicity, Customized: Asiatic | participants | 3 |
| Race/Ethnicity, Customized: Arabic | participants | 2 |
| Race/Ethnicity, Customized: Black African | participants | 0 |
| Race/Ethnicity, Customized: Other Race | participants | 3 |
| Region of Enrollment: Germany | participants | 520 |
6. Primary Endpoint
The registry lists the primary outcome as Clinical Global Impression of Change (CGI-C) at Month 6, measured over Month 6.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the investigator’s Clinical Global Impression of Change (CGI-C) at Month 6. Investigators compared the subject’s clinical status with baseline and selected the category that best described the subject’s condition over the past 6 months compared with baseline. The response options range from very much improved through no change to very much worse, with intermediate categories in both directions.
As a general measurement concept, a global change rating can summarize a clinician’s overall judgment rather than reduce clinical status to a single symptom count. This can make it useful for describing perceived overall change in a clinical setting. It is a judgment-based measure, however: the rating depends on the investigator’s assessment and on the information available to that investigator. The registry record does not report how investigators were trained, whether ratings were made consistently across sites, or why this endpoint was selected over another measure.
The categories have a natural direction from improvement to worsening, but the record does not state whether the statistical analysis treated them as ordered categories, combined categories, or analyzed them in another way. It also does not report the number of subjects in each category. Consequently, the endpoint definition alone establishes what was assessed, not the direction or magnitude of the study’s result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the outcome and the population included in its analysis, but it does not report the distribution of CGI-C responses. It is therefore not possible to describe the proportion rated improved, unchanged, or worse, or to judge the precision of such a result. No confidence interval, p-value, or effect estimate for the primary endpoint is reported in the registry record. The listed categories and analysis count do not substitute for the outcome results.
The endpoint is an investigator’s rating of change relative to baseline over the past 6 months. It is not a randomized comparison of Vimpat® with a control treatment. A change noted during routine treatment could be associated with many aspects of care and the underlying condition; the study design described in the record does not isolate a causal treatment effect. The baseline reference helps define the rating but does not provide the counterfactual comparison that a concurrent control group could offer.
Interpretation also depends on how the CGI-C categories were summarized and analyzed. The registry record gives seven response categories, but it does not report whether the analysis preserved all categories or combined them. It gives no category counts, uncertainty estimates, or statistical test result. Without these details and results, a reader cannot determine how much the observed ratings varied or how precisely any group-level summary was estimated.
The enrollment and analysis-population counts describe different stages or definitions, but the record does not explain the participant flow. The Full Analysis Set is described as comprising treated subjects who met inclusion criteria and had valid baseline and post-baseline seizure-frequency values; the definition is not complete in the registry record. The primary outcome description says 515 subjects were included in its analysis. These statements do not establish why other enrolled subjects were absent from that analysis, or whether missingness was related to clinical status.
For safety, the record lists 56 subjects with serious adverse events among 571 at risk and 114 with other adverse events among 571 at risk. It also lists several serious adverse-event terms and percentages. These are descriptive figures in the treated study population, not comparative estimates. The record does not provide a control-group rate or enough information to attribute events to treatment. The absence of a reported death count is not evidence that no deaths occurred; deaths are not reported in the registry record.
Overall, the available record supports a description of the study setting, its planned outcome concepts, and some safety counts. It does not supply the primary efficacy result needed to characterize the distribution of clinical-change ratings, nor does it provide a controlled estimate of treatment effect. Any inference should remain within those limits.
9. Statistical Methods Explained
Statistical methods connect a study question to the way outcomes are measured, summarized, and compared. In this record, the primary measure is a categorical investigator rating, while the secondary outcomes include seizure-frequency changes and adverse-event incidence. These outcome types require different summaries. The registry record does not report the statistical analysis plan or the methods used for the clinical outcome results, so general statistical principles should not be mistaken for methods confirmed to have been used in this study.
What does a confidence interval describe?
As a general statistical concept, a confidence interval expresses uncertainty around an estimate. A narrow interval indicates greater precision under the assumptions of the method; a wide interval indicates less precision. An interval does not correct bias from study design or missing information. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be assessed from the outcome definition or analysis-population count alone.
How should a categorical outcome be summarized?
The CGI-C offers ordered verbal categories, from improvement through no change to worsening. A statistical summary could retain the category distribution, use a prespecified grouping, or apply a model that accounts for the ordering. These approaches answer somewhat different questions and rely on different assumptions. The record does not say which approach was used, and it does not report the category counts. It is therefore not appropriate to reconstruct a summary or assume that the categories were combined in a particular way.
A p-value, if reported, would address compatibility between data and a specified null hypothesis under the assumptions of a statistical test. It would not measure clinical importance, establish causality, or describe precision on its own. No primary-outcome p-value is reported in the registry record. In this non-interventional study without a stated comparator, even a hypothetical statistically unusual change from baseline would not by itself identify the cause of that change.
Why can seizure-frequency data be challenging?
Seizure counts are count outcomes. As a general matter, count data may vary more than a simple model assumes, a feature called over-dispersion. When present, over-dispersion can make standard errors too small and confidence intervals too narrow if the analysis does not accommodate it. Count outcomes can also have many zero values or substantial differences between people. The record lists seizure-frequency outcomes but does not report the count distributions, model, exposure-time handling, or assessment of over-dispersion. It is not possible to say whether these issues arose or how they were addressed.
Repeated assessments at baseline and follow-up can also be statistically related within a person. General methods for repeated measurements account for this dependence rather than treating each measurement as unrelated. The registry record names changes at Month 3 and Month 6, but does not describe the analysis of these measurements or whether all scheduled observations were available for each subject.
What do the planning assumptions mean?
The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. For time-to-event calculations, the illustration concerns the total number of events; other illustrations concern participants per arm for 80% power or another stated power level. These are planning assumptions, not evidence that the study was designed as a randomized two-arm trial. The record describes one routine-treatment group and does not state that allocation was randomized.
Such sample-size calculations are hypothetical planning illustrations, not observed power. They ask what sample size might be needed under stated assumptions; they do not establish the probability that a completed study has detected a real effect. The registry record does not report the study’s own sample-size justification or a statistical plan that would connect these illustrations to the study design. No numerical planning result is included in the registry record, and no new sample size can be inferred from the enrollment alone.
What can safety counts establish?
Counts of participants with an event describe how many people experienced at least one event under the recorded definitions. They are not the same as the number of event episodes, and they do not establish whether an event was caused by treatment. Interpretation of event proportions also depends on the at-risk population, event definitions, observation time, and how repeat events are handled. The record gives at-risk counts and affected-participant counts for serious and other adverse events, but does not report the serious-event definition, exposure-adjusted rates, or comparative estimates.
Finally, methods for missing data matter because an analysis of only observed outcomes may represent a selected subset if outcome availability is related to participants’ status. General approaches include describing missingness, analyzing according to a stated population definition, and conducting sensitivity analyses under alternative assumptions. The record gives a primary-outcome analysis count and a partial description of the Full Analysis Set, but it does not report reasons for missing outcome values or any missing-data method. These omissions limit assessment of both precision and possible selection effects.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary CGI-C endpoint and secondary outcomes covering seizure-frequency changes at Month 3 and Month 6, plus adverse-event incidence. When multiple outcomes or time points are examined, the chance of at least one apparently notable result can increase. General approaches include identifying a primary endpoint in advance, adjusting for multiple comparisons, or treating secondary analyses as exploratory. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or which outcomes were included in any formal statistical testing. No p-values or outcome estimates are reported in the registry record.
The primary outcome description reports that 515 subjects were included in its analysis and describes a Full Analysis Set of 520 subjects. It does not give a complete participant flow or explain why the counts differ. The definition of the Full Analysis Set says that subjects had received Vimpat® at least once, fulfilled inclusion criteria, and had valid baseline and post-baseline seizure-frequency values; the remaining definition is not reported in the registry record. It is therefore not possible to determine from this description how the primary CGI-C analysis population was defined beyond the stated count.
Missing-data methods are not reported in the registry record. There is no description of the amount or pattern of missing endpoint data, reasons for missingness, imputation, or sensitivity analyses. As a general principle, missingness can affect both representativeness and uncertainty when the probability that an outcome is observed is related to a participant’s condition. The available counts alone do not show whether that concern applies in this study or how it was addressed.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Vimpat® | 56 | 571 | 9.8% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Vimpat® | 114 of 571 |
Most frequent serious adverse event terms
| Event term | Organ system | Vimpat® |
|---|---|---|
| Convulsion | Nervous system disorders | 10 of 571 |
| Grand mal convulsion | Nervous system disorders | 9 of 571 |
| Epilepsy | Nervous system disorders | 7 of 571 |
| Dizziness | Nervous system disorders | 5 of 571 |
| Status epilepticus | Nervous system disorders | 4 of 571 |
| Syncope | Nervous system disorders | 4 of 571 |
| Fall | Injury, poisoning and procedural complications | 3 of 571 |
| Conversion disorder | Psychiatric disorders | 3 of 571 |
| Pneumonia aspiration | Respiratory, thoracic and mediastinal disorders | 3 of 571 |
| Angina pectoris | Cardiac disorders | 2 of 571 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Vimpat® |
|---|---|---|
| Fatigue | General disorders | 71 of 571 |
| Dizziness | Nervous system disorders | 60 of 571 |
Serious events with the highest arm-level rate: convulsion (1.8%), grand mal convulsion (1.6%), epilepsy (1.2%), dizziness (0.9%), status epilepticus (0.7%).
The safety figures are descriptive counts from the Vimpat® group. The registry record lists 56 participants with serious adverse events among 571 at risk, and 114 participants with other adverse events among 571 at risk. These counts refer to participants affected, not necessarily to the number of separate event episodes. The record does not provide a control group, exposure-adjusted rates, or a definition of serious adverse events, so the figures should not be read as comparative treatment effects.
The listed serious adverse-event terms and percentages are Convulsion, 1.8%; Grand mal convulsion, 1.6%; Epilepsy, 1.2%; Dizziness, 0.9%; Status epilepticus, 0.7%; and Syncope, 0.7%. These are registry-listed term percentages; the record does not provide further detail on their calculation or on the relationship between terms and affected participants. A participant may experience more than one event, so term entries should not be treated as mutually exclusive categories.
The death count is not reported in the registry record. A missing death figure should not be interpreted as zero. The adverse-event counts describe events recorded during the study; they do not by themselves establish that treatment caused an event or characterize risk relative to another treatment.
12. What the Result Does, and Does Not, Mean
The record establishes that the study collected prospective information about Vimpat® used as adjunctive therapy to one baseline antiepileptic drug in routine clinical practice in Germany. It defines an investigator-rated clinical-change outcome at Month 6 and lists seizure-frequency and tolerability outcomes. The safety record includes counts of participants with serious and other adverse events, along with selected serious-event terms.
The record does not report the distribution of primary CGI-C categories, a numerical summary of clinical change, or uncertainty around such a summary. It therefore does not show how many participants were rated improved, unchanged, or worse, and does not permit an assessment of the precision of those outcomes. The outcome definition is not a result.
Even if outcome changes were available, a non-interventional study without a described concurrent comparator would not, on its own, distinguish treatment effects from other influences. Clinical status can change over time for reasons unrelated to a specific treatment. The comparison with baseline defines the CGI-C question, but it does not supply the control experience needed for a like-for-like causal comparison.
The adverse-event counts should likewise be read as observed descriptive information in the recorded treatment group. They do not estimate an excess risk relative to an untreated or differently treated group, and they do not establish causation. The registry record does not report a death count, event definitions in detail, or a comparative safety analysis.
Thus, the record is informative about the study’s setting, treatment context, endpoints, and some recorded safety counts. It does not provide enough outcome results or analysis detail to quantify the primary clinical-change result or support a controlled causal conclusion. Those limits are central to interpreting what this study can say.
13. Why This Trial Matters Statistically
This study is statistically relevant because it concerns treatment in daily clinical practice rather than a randomized comparison. Routine-care data can describe how an intervention is used and what outcomes or adverse events are recorded in that setting. Such information addresses a different question from a controlled trial: it reflects observed experience, but is more exposed to differences in patient characteristics, clinical decisions, follow-up, and measurement.
The primary endpoint also illustrates the distinction between defining an outcome and reporting its result. The registry record specifies a clinician-rated scale with categories from improvement to worsening and identifies the assessment time. Yet without category counts and a statistical summary, readers cannot evaluate the observed distribution or its precision. Clear outcome definitions are valuable, but they cannot substitute for results.
The study also underscores why analysis populations and missingness need explanation. The record gives an enrollment count, a Full Analysis Set count, and a primary-outcome analysis count, but not a complete flow or the reasons for exclusions. Transparent reporting would help readers understand which participants contributed to each result and whether missing outcomes could affect interpretation.
Finally, safety event counts are meaningful as descriptions of recorded events, but they are not comparative risk estimates. A denominator and event count do not establish causation, especially in a single-group observational design. Statistical interpretation depends not only on numerical summaries but on how participants were selected, outcomes were measured, and comparisons were constructed. Those design details constrain conclusions even when counts are available.
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 study is non-interventional and the registry record describes one treatment group, without a concurrent comparator. It also states that allocation was not stated. Accordingly, the design does not support a direct like-for-like comparison with another treatment, and observed change from baseline cannot be attributed uniquely to Vimpat® from the information reported.
The primary endpoint is based on investigator judgment. The record defines the CGI-C categories and comparison period, but does not report rating procedures, assessor consistency, or whether investigators were aware of other clinical information when making ratings. The registry record also does not report the category distribution or analysis method. These omissions prevent assessment of how the rating was summarized and how much uncertainty surrounds the result.
Participant accounting is incomplete. Enrollment is 576, the Full Analysis Set is described as 520 subjects, and 515 subjects are reported in the primary-outcome analysis. The record does not explain the differences or give a full flow of participants. Its Full Analysis Set definition is incomplete in the registry record. Reasons for missing data and methods to address them are also not reported.
The secondary outcomes involve seizure-frequency changes at specified follow-up assessments and adverse events, but their numerical results and analysis methods are not included in the registry record. The record does not report a statistical analysis plan, multiplicity handling, or a sample-size justification for the study. It also does not report detailed event definitions, exposure-adjusted safety rates, or a death count. These are limitations of the available registry information; they do not establish that a particular analysis or event did or did not occur.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Vimpat® Added as Adjunctive Therapy to One Baseline Antiepileptic Drug — NCT01098162.
- Registry record last updated 2014-09-03; status last verified 2014-08.
- Results first posted 2014-07-22.
- 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.
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18. Record Summary
NCT01098162 is a completed, non-interventional post-marketing study of Vimpat® added to one baseline antiepileptic drug in routine clinical practice in Germany. The record gives enrollment of 576 and identifies investigator-rated CGI-C at Month 6 as the primary outcome. It describes a Full Analysis Set of 520 subjects and says 515 were included in the primary-outcome analysis. Secondary outcomes address seizure-frequency changes and adverse-event incidence.
The record reports 56 participants with serious adverse events among 571 at risk and 114 with other adverse events among 571 at risk. It lists several serious adverse-event terms with percentages. The primary CGI-C category results, statistical analysis methods, missing-data methods, and death count are not reported in the registry record. With no stated randomized comparator, the available description is observational and does not establish a causal treatment effect.