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 Extension Study Of Long-Term Safety And Efficacy Of Pregabalin As Monotherapy (Lyrica) In Patients With Partial Seizures (NCT00596466), a non-randomized phase 3 study. The primary outcome is Seizure Frequency.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00596466 |
| Phase | Phase 3 |
| Condition | Epilepsy |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 75 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer's Upjohn has merged with Mylan to form Viatris Inc. |
| Results posted | Yes |
2. Clinical Question
NCT00596466 asked about long-term safety and efficacy of pregabalin used by itself in patients with epilepsy and partial seizures. It was an extension study to a previous clinical trial. The registry description identifies pregabalin as the study drug and frames its use as monotherapy, without another anti-epileptic medication.
The study's primary outcome was seizure frequency, with a timeframe from baseline up to Week 28. The registry says individual participants' seizure-frequency data were collected and reviewed. It also says no statistical inferences were conducted because the study had no comparator agent. Consequently, the posted record does not give a comparative estimate of the effect of pregabalin on seizure frequency.
The registry's design was non-randomized and single-group, with no masking. It therefore describes experience among participants receiving pregabalin in this study, rather than a randomized comparison with another treatment or control condition. The registry does not report a separate control group or a treatment contrast for the primary outcome.
The clinical question can be organized as follows:
Population
Patients with epilepsy and partial seizures participating in an extension study after a previous clinical trial.
Intervention
Pregabalin administered as monotherapy, without another anti-epileptic medication.
Comparator
No comparator agent; the study was a non-randomized, single-group study.
Primary question
Seizure frequency from baseline up to Week 28, considered alongside long-term safety. The registry reports that seizure data were collected and reviewed but not analyzed for statistical inference.
3. Trial Design
NCT00596466 is listed as a Phase 3 study with non-randomized allocation, no masking, and a single-group model. It is described as an open-label, multicenter extension study to determine long-term safety and efficacy of pregabalin as monotherapy in patients with partial seizures. The registry identifies epilepsy as the condition and pregabalin as the drug intervention.
The study enrolled 75 participants. Its recorded start was 2008-04, primary completion was 2011-12, and status is completed. These are registry-record milestones; they do not establish how long any individual participant was followed. The primary outcome timeframe is stated separately as baseline up to Week 28.
Because there was one study group and no comparator agent, the design does not support a randomized between-group treatment contrast. Non-randomized, open-label participation also means that the record does not describe masking of participants or study personnel. The registry does not report further details about the intervention schedule, eligibility criteria, specific follow-up visits, or how the extension related operationally to the previous trial.
The registry describes 3 outcome measures and 0 analyses. For the primary seizure-frequency outcome, it explicitly states that individual participant data were collected and reviewed but no statistical inferences were conducted because there was no comparator agent. A numerical seizure-frequency estimate, its variability, and an inferential result are not reported in the registry record.
The intervention description is limited to pregabalin as a drug and the monotherapy framing. Further details about dose, titration, adherence, or changes in treatment are not reported in the registry record. The registry also does not report a statistical analysis plan, a sample-size justification, or a protocol-based hypothesis test. Planning illustrations based on an observed effect are not part of the trial's own design and cannot be interpreted as evidence that the trial was planned or powered for a particular 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: Participants were eligible for the current study A0081160 (NCT00596466) if they adequately responded to pregabalin treatment in protocol A0081047 (NCT00524030).
Overall Study
| Stage | Pregabalin |
|---|---|
| STARTED | 75 |
| Enrolled, Treated | 73 |
| COMPLETED | 58 |
| NOT COMPLETED | 17 |
Reasons for not completing this period:
| Reason | Pregabalin |
|---|---|
| Lack of Efficacy | 5 |
| Adverse Event | 4 |
| Withdrawal by Subject | 2 |
| Protocol Violation | 2 |
| Unpecified | 2 |
| Enrolled, not treated | 2 |
Analysis population for the primary outcome, as defined in the registry: Not analyzed; Per protocol, seizure frequency data for individual participants were collected and reviewed but no statistical inferences were conducted because there was no comparator agent for this study.
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.
| Characteristic | Unit | Pregabalin |
|---|---|---|
| Participants analysed | 75 | |
| Age, Customized: 18-44 years | Participants | 48 |
| Age, Customized: 45-64 years | Participants | 23 |
| Age, Customized: Greater than or equal to (≥) 65 years | Participants | 4 |
| Sex: Female, Male: Female | Participants | 38 |
| Sex: Female, Male: Male | Participants | 37 |
6. Primary Endpoint
The registry lists the primary outcome as Seizure Frequency, measured over Baseline up to Week 28.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled Seizure Frequency. Its stated timeframe is baseline up to Week 28. In general, seizure frequency is a way to describe how often seizures occur over a defined observation period. It is clinically relevant to the study's stated focus on partial seizures because it tracks the event the treatment was intended to address in the study population.
The record does not specify the unit, parameter, or dispersion for this outcome. It does not provide a numerical seizure-frequency result, a measure of uncertainty, or a statistical comparison. The outcome description says individual participant data were collected and reviewed, but no statistical inferences were conducted because there was no comparator agent.
That distinction matters: collecting and reviewing observations is not the same as estimating a treatment contrast or testing a prespecified hypothesis. In a single-group study, changes from baseline could in principle be described, but the registry does not report such an estimate. Nor does it report how seizure-frequency values were summarized, how baseline was defined, or how incomplete observations were handled. Those details are not reported in the registry record.
General statistical context: an endpoint is useful when its definition, measurement window, and analysis are clear enough for readers to understand what is being estimated. The stated outcome and timeframe identify the topic and observation window, but the absent numerical result and analysis details limit interpretation of the seizure-frequency evidence in this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted record identifies the study as a single-group evaluation of pregabalin monotherapy and reports descriptive safety counts. It does not report a statistical result for the primary seizure-frequency outcome. The registry explicitly explains that seizure-frequency information was collected and reviewed, but that statistical inferences were not conducted because there was no comparator agent. Accordingly, the record does not establish an estimate of how seizure frequency changed, how variable that change was, or how it compares with an alternative treatment or control condition.
For adverse events, 73 participants are listed as at risk for serious adverse events, and 3 are listed as affected. For other adverse events, 73 are listed as at risk and 14 as affected. The registry lists Convulsion at 2.7%, Road traffic accident at 1.4%, and Transient ischaemic attack at 1.4% among the top serious adverse-event terms. These entries describe the posted safety data; they do not by themselves establish causation or provide a comparative risk estimate.
The study enrollment is 75, while the safety group lists 73 at risk. The record does not explain this difference. It also does not report a numeric death count: the death entry is null, so deaths are not reported in the registry record. A null entry should not be read as evidence that no deaths occurred.
General statistical context: a descriptive count tells readers how many participants were recorded as affected within the stated group. A comparative treatment effect requires a suitable comparison and an estimand that specifies the outcome, population, and contrast. A single-group study can describe observations during treatment, but it cannot separate treatment-associated change from other explanations such as the natural course of the condition, prior treatment history, or changes in observation.
The record's lack of inferential analysis is therefore a central interpretive feature, not an omitted p-value that can be reconstructed from the summary. There is no reported primary-outcome estimate to assess for precision, and no reported confidence interval. General statistical context: a confidence interval expresses uncertainty around an estimated quantity; without a reported estimate and analysis, precision for seizure frequency cannot be evaluated from this record.
The registry's completion status and stated enrollment describe study conduct at a high level, but they do not fill these analytical gaps. The posted results support a limited description of the recorded safety counts and of the primary outcome collection process. They do not support a causal or comparative conclusion about efficacy, nor a claim that a treatment effect is absent. The registry record does not report the underlying seizure-frequency data or a statistical analysis of them.
9. Statistical Methods Explained
General statistical context: methods determine what a study's observations can answer. A randomized comparison can, subject to its assumptions and conduct, estimate differences between assigned groups. A single-group study instead describes observations among participants in that group. NCT00596466 is listed as non-randomized and single-group, and the outcome description states that there was no comparator agent. The registry therefore does not report a between-group estimate for seizure frequency.
What does a single-group result describe?
In a single-group study, observations during treatment can be described, and a before-and-after summary may sometimes be informative. However, a change over time is not automatically attributable to treatment. Changes may also reflect the condition's course, prior participation or treatment, altered observation, or other influences. This is general statistical context, not a claim that any particular influence occurred in this study. The registry does not report a numerical change from baseline for seizure frequency, so such a description cannot be made from the posted results.
The record specifically says individual participant seizure-frequency data were collected and reviewed, but no statistical inferences were conducted because there was no comparator agent. It gives no outcome unit, summary parameter, dispersion measure, or inferential result. These missing elements mean that readers cannot assess the size of any observed change or its precision from the registry record.
Why does a comparator matter?
General statistical context: a comparator helps distinguish outcomes under one treatment strategy from outcomes under another. In randomized trials, allocation can make groups comparable on average, while statistical analysis quantifies the observed contrast and uncertainty. Here, the record lists no comparator and no randomization. The study can contribute descriptive experience with the intervention, but the primary outcome information as posted does not provide a comparative treatment effect.
Masking is listed as none. General statistical context: masking can reduce the influence of knowledge about treatment assignment on some aspects of measurement and reporting. Its absence does not tell readers the direction or magnitude of any bias in this particular study. It does mean that the registry does not describe a masked assessment for this outcome.
How should the safety counts be read?
General statistical context: an at-risk count defines the denominator associated with a recorded event category, while an affected count describes participants recorded as having an event. The registry lists 73 at risk and 3 affected for serious adverse events, and 73 at risk and 14 affected for other adverse events. These are descriptive summaries, not estimates from a randomized comparison. They do not show whether the events were caused by treatment or whether event rates differ from another group.
The serious-event terms are listed with percentages: Convulsion at 2.7%, Road traffic accident at 1.4%, and Transient ischaemic attack at 1.4%. The record does not give a fuller account of event timing, recurrence, severity beyond the serious classification, or relatedness to treatment in the outcome summary. A listed term and percentage should therefore be read as a registry safety entry, not as a causal conclusion.
What can planning illustrations tell readers?
General statistical context: a sample-size calculation can illustrate the number of participants needed under specified assumptions to detect a chosen effect with a chosen error rate and power. Such a calculation is prospective only when it reflects the study's actual design and assumptions. The registry's stated planning illustration assumptions are 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. Time-to-event illustrations use total events; other illustrations use participants per arm.
Those assumptions describe planning illustrations, not the design of this single-group study. They do not establish the trial's planned sample size, its actual power, or an observed effect. Sample-size illustrations are not observed power. The registry does not report that the trial used those assumptions for its own design, and no trial-specific sample-size justification is reported in the registry record.
What is not available for independent analysis?
The record reports 0 analyses and provides no numerical primary-outcome result. It does not report the analysis population, a statistical model, adjustment variables, an uncertainty estimate, or a missing-data method. Without those details and without participant-level observations, readers cannot reproduce or independently evaluate an inferential analysis of seizure frequency from the registry record.
General statistical context: reproducibility depends on a sufficiently clear description of the data, estimand, and analysis choices. Missing information should not be filled by assuming a conventional method. The record's explicit statement that no statistical inference was conducted takes precedence over any hypothetical method that could have been used. The appropriate statistical reading is therefore descriptive for the posted safety information and non-inferential for the primary seizure-frequency outcome.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 3 outcome measures and 0 analyses. It does not report a multiplicity adjustment, a hierarchy of outcome tests, or a prespecified strategy for handling multiple comparisons. Because the primary seizure-frequency outcome was not subjected to statistical inference according to its description, the record does not present a family of primary-outcome tests for readers to interpret. Whether other analyses were planned is not reported in the registry record.
General statistical context: multiplicity arises when several outcomes or hypotheses are tested, because repeated testing can increase the chance of at least one apparently notable result. A prespecified analysis strategy can clarify which outcomes are confirmatory and how uncertainty is controlled. The absence of such details in this record should not be taken to mean that a particular adjustment was or was not used outside what the record states.
The primary outcome description says participant seizure-frequency data were collected and reviewed, but no statistical inference was conducted. The registry does not report how missing seizure observations were handled, how many participants contributed data to each assessment, or whether any analysis population was defined. It also does not report the criteria used to include participants in a per-protocol population, although the outcome description uses the phrase per protocol.
General statistical context: missing-data methods matter because conclusions can depend on whether unavailable observations differ systematically from observed ones. Without a reported flow of outcome availability or an analysis method, the impact of missing observations cannot be evaluated. The 75 enrolled participants and the 73 listed as at risk for the safety summaries do not establish the number with evaluable seizure-frequency data. The reason for the difference is not reported in the registry record.
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 |
|---|---|---|---|
| Pregabalin | 3 | 73 | 4.1% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 3% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Pregabalin | 14 of 73 |
Most frequent serious adverse event terms
| Event term | Organ system | Pregabalin |
|---|---|---|
| Convulsion | Nervous system disorders | 2 of 73 |
| Road traffic accident | Injury, poisoning and procedural complications | 1 of 73 |
| Transient ischaemic attack | Nervous system disorders | 1 of 73 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Pregabalin |
|---|---|---|
| Nausea | Gastrointestinal disorders | 4 of 73 |
| Headache | Nervous system disorders | 4 of 73 |
| Weight increased | Investigations | 3 of 73 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 3 of 73 |
| Convulsion | Nervous system disorders | 3 of 73 |
Serious events with the highest arm-level rate: convulsion (2.7%), road traffic accident (1.4%), transient ischaemic attack (1.4%).
The registry lists 73 participants at risk for serious adverse events, with 3 affected. For other adverse events, it lists 73 at risk and 14 affected. The top serious adverse-event terms are Convulsion at 2.7%, Road traffic accident at 1.4%, and Transient ischaemic attack at 1.4%. These are the safety entries reported for the pregabalin group.
General statistical context: counts and percentages are descriptive. They indicate what was recorded in the study group, but do not by themselves establish that an event was caused by the intervention. With no comparator group, the record does not provide a comparative event rate or a basis for estimating how these counts differ from another treatment or from no treatment.
The registry does not report the death count as a number; that field is null, so deaths are not reported in the registry record. Nor does the safety summary state the event-level details needed to assess timing, recurrence, or treatment relatedness. The listed affected counts should be read as participant counts, not necessarily as total event counts. The posted safety data are informative as descriptive records, but they cannot answer comparative or causal safety questions on their own.
12. What the Result Does, and Does Not, Mean
The record establishes that NCT00596466 was completed as a Phase 3, open-label, non-randomized, single-group extension study of pregabalin monotherapy in patients with partial seizures. It records enrollment of 75 participants and defines seizure frequency from baseline up to Week 28 as the primary outcome. It also records a safety group of 73 participants at risk for serious and other adverse events, with 3 and 14 affected, respectively.
For seizure frequency, the record says data were collected and reviewed but no statistical inferences were conducted because the study had no comparator agent. The registry does not report a numerical seizure-frequency result or an uncertainty estimate. As a result, the posted record does not quantify a change in seizures or show how precisely a treatment-associated change was estimated.
These limitations do not mean that no change occurred, and they do not establish that pregabalin had no effect. They mean that the registry record does not provide a statistical estimate capable of supporting those conclusions. Likewise, the safety counts do not establish that the listed events were caused by pregabalin. They describe recorded events among participants in the study group, without a comparative reference group.
General statistical context: evidence from a single group can help characterize observations in that group, but causal attribution generally requires a design and analysis that address alternative explanations. A randomized comparator can support a treatment contrast; a single-group extension study does not supply that contrast. The open-label, non-randomized design and absence of reported inferential analysis are therefore relevant when judging what the record can answer.
Interpretation is further constrained by absent reporting on the seizure-frequency unit, summary measure, dispersion, missing-data handling, analysis population, and trial-specific sample-size justification. These details are not reported in the registry record. The record can be read as documenting a study and its posted descriptive safety information, while leaving the primary efficacy question without an inferential result in the registry entry.
13. Why This Trial Matters Statistically
This study matters statistically because it illustrates the difference between collecting an outcome and reporting an estimate that supports inference. The registry says participant seizure-frequency data were collected and reviewed, yet it also states that no statistical inferences were conducted because no comparator agent was present. That distinction is essential: measurement alone does not tell readers the size or precision of an effect.
The design also clarifies the limits of single-group evidence. NCT00596466 is listed as non-randomized, unmasked, and single-group. The posted safety counts describe participants in that group, but there is no like-for-like control comparison. Without a comparator, observed events and any possible changes in seizure frequency cannot be interpreted as differences attributable to pregabalin through a between-group analysis.
The safety entries further show why denominators and outcome definitions matter. The registry identifies 73 participants at risk in each safety category and reports the numbers affected, while the overall enrollment is 75. The record does not explain the difference. It also leaves the death entry null rather than reporting a count. Careful interpretation requires preserving those distinctions instead of filling gaps with assumptions.
General statistical context: transparent reporting of the analysis population, missing-data approach, endpoint definition, and uncertainty helps readers judge the strength and limits of evidence. Those details are not reported for the primary outcome in this registry record. The study remains statistically informative as an example of a completed extension study with descriptive safety entries and a primary endpoint for which the registry explicitly reports no inferential analysis.
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 main limitation for interpreting efficacy is that the registry does not report a numerical result for seizure frequency. It gives the outcome title and timeframe, and states that participant data were collected and reviewed, but no statistical inference was conducted because there was no comparator agent. The unit, summary measure, dispersion, and uncertainty around any estimate are not reported in the registry record.
The non-randomized, single-group design and absence of masking limit the kinds of comparisons that can be made from the posted information. The record does not contain a control group, a randomized contrast, or a reported estimate of change from baseline. It therefore cannot establish a comparative treatment effect from the primary outcome.
Reporting of study conduct is also limited. The intervention is identified as pregabalin monotherapy, but details about dose, treatment changes, adherence, and specific assessment procedures are not reported in the registry record. The record does not explain why 75 participants were enrolled while the safety summaries list 73 at risk. A numerical death count is not reported in the registry record.
Analysis details are absent, including the trial-specific sample-size justification, statistical analysis plan, analysis population, and approach to missing seizure-frequency data. The number of participants with evaluable primary-outcome observations is not reported in the registry record. The safety summary does not provide the comparative information needed to distinguish treatment-associated events from events that might occur for other reasons. These limitations constrain interpretation of the posted results; they do not establish that an unreported result was favorable or unfavorable.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Extension Study Of Long-Term Safety And Efficacy Of Pregabalin As Monotherapy (Lyrica) In Patients With Partial Seizures — NCT00596466.
- Registry record last updated 2021-01-26; status last verified 2012-08.
- Results first posted 2012-09-11.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT00596466 was a completed Phase 3, open-label, non-randomized, single-group extension study of pregabalin monotherapy for patients with partial seizures. Enrollment was 75. The study recorded its start as 2008-04 and primary completion as 2011-12.
The primary outcome was seizure frequency from baseline up to Week 28. The registry says individual participant data were collected and reviewed, but no statistical inferences were conducted because there was no comparator agent. A numerical primary-outcome result is not reported in the registry record.
For safety, 73 participants were listed as at risk for serious adverse events, with 3 affected; 73 were listed as at risk for other adverse events, with 14 affected. The top serious terms were Convulsion at 2.7%, Road traffic accident at 1.4%, and Transient ischaemic attack at 1.4%. A death count is not reported in the registry record. The posted information is descriptive and does not provide a comparative treatment-effect estimate.