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 Assessing The Long-Term Safety And To Explore The Long-Term Efficacy Of Zonisamide As Monotherapy In Newly Diagnosed Partial Seizures (NCT00848549), a randomized phase 3 study. The primary outcome is Percentage of Participants Remaining in the Study at Each Visit.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00848549 |
| Phase | Phase 3 |
| Condition | Epilepsy |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 295 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Eisai Inc. |
| Results posted | Yes |
2. Clinical Question
Population
People with newly diagnosed partial seizures. The study condition is listed as epilepsy. The primary-outcome population is defined as the Intent-to-Treat (ITT) Population: all subjects who received at least one dose of investigational product.
Intervention
Zonisamide as monotherapy in a long-term extension study. The study objective was to assess long-term safety and tolerability and explore long-term efficacy.
Comparator
Carbamazepine as monotherapy. The registry record describes a randomized, double-blind, parallel study, but does not report further details about how treatment assignment was implemented or maintained.
Primary question
What percentage of participants remained in the study at each scheduled visit, from 3 through 27 months? The endpoint was defined as the percentage remaining on study at each visit, starting from the first dose of study drug in the extension phase. Visit-specific percentages and confidence intervals are not reported in the registry record.
The study also listed outcomes concerning time to drop-out due to lack of efficacy, time to drop-out due to an adverse event, seizure-free periods, and quality of life. Those outcomes address different aspects of continued participation, seizure control, tolerability, and participants’ reported experience. The registry record names these measures, but does not report their results in the information available for this analysis.
The main question is therefore about retention over scheduled follow-up, rather than a single direct measure of seizure reduction. Retention can describe how many participants remain under study, but it does not by itself explain why others leave or establish whether treatment affected seizure outcomes. The listed drop-out outcomes could help distinguish reasons for leaving, while the seizure-free and quality-of-life outcomes address other dimensions. Their estimates and analysis details are not reported in the registry record.
3. Trial Design
This was a Phase 3 randomized, double-blind, parallel extension study sponsored by Eisai Inc. It compared zonisamide with carbamazepine as monotherapy in people with newly diagnosed partial seizures. The study enrolled 295 participants. The registry record lists the study as completed, with a start date of 2008-10 and primary completion in 2011-06.
The extension study is identified as Study 314, NCT00848549. The adverse-event record also includes groups from Base Study 310, NCT00477295. The extension and base-study figures are separate sets of safety counts in the registry record; they should not be treated as a single cohort or as interchangeable follow-up periods. Further details about how participants entered the extension, the treatment history before extension, and the relationship between base-study and extension participants are not reported in the registry record.
Randomization is intended to make treatment groups comparable on average, while double blinding is intended to reduce the influence of treatment knowledge on participant or study-team assessments. These are general design concepts; the registry record does not describe the specific randomization procedure, concealment method, or blinding procedures. It identifies a parallel model, meaning the treatment groups are considered separately rather than participants crossing between treatments, but does not report additional operational details.
The stated primary outcome was retention at 3, 6, 9, 12, 15, 18, 21, 24, and 27 months. Its definition starts follow-up from the first dose of study drug in the extension phase. The record lists secondary outcomes for time to drop-out due to lack of efficacy, time to drop-out due to an adverse event, a consecutive seizure-free period, and change in QOLIE-31-P overall score. Specific eligibility criteria, treatment doses, follow-up procedures, and the planned statistical analysis are not reported in the registry record.
Although the study objective refers to long-term safety and to exploring long-term efficacy, the primary outcome is a measure of study retention. The registry record does not present the retention estimates or a treatment comparison for that outcome in the information available for this analysis. The design description alone cannot establish what the results were.
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.
E2090-E044-310 (Base Study) Disposition
| Stage | Zonisamide | Carbamazepine |
|---|---|---|
| STARTED | 282 | 301 |
| COMPLETED | 161 | 192 |
| NOT COMPLETED | 121 | 109 |
Reasons for not completing this period:
| Reason | Zonisamide | Carbamazepine |
|---|---|---|
| Adverse Event | 31 | 35 |
| Withdrawal by Subject | 35 | 24 |
| Lack of Efficacy | 23 | 23 |
| Protocol Violation | 3 | 8 |
| Physician Decision | 4 | 5 |
| Lost to Follow-up | 21 | 11 |
| Other | 4 | 3 |
E2090-E044-310 (Base Study) Transition
| Stage | Zonisamide | Carbamazepine |
|---|---|---|
| STARTED | 161 | 192 |
| COMPLETED | 137 | 158 |
| NOT COMPLETED | 24 | 34 |
Reasons for not completing this period:
| Reason | Zonisamide | Carbamazepine |
|---|---|---|
| Chose not to enter 314 Extension study | 24 | 34 |
E2090-E044-314 (Extension Study)
| Stage | Zonisamide | Carbamazepine |
|---|---|---|
| STARTED | 137 | 158 |
| COMPLETED | 120 | 134 |
| NOT COMPLETED | 17 | 24 |
Reasons for not completing this period:
| Reason | Zonisamide | Carbamazepine |
|---|---|---|
| Adverse Event | 2 | 1 |
| Protocol Violation | 1 | 2 |
| Withdrawal by Subject | 8 | 12 |
| Lack of Efficacy | 1 | 1 |
| Physician Decision | 0 | 2 |
| Other | 5 | 6 |
Analysis population for the primary outcome, as defined in the registry: The Intent-to-Treat (ITT) Population is defined as all subjects who received at least one dose of investigational product(IP)
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 | Zonisamide | Carbamazepine | Total |
|---|---|---|---|---|
| Participants analysed | 282 | 301 | 583 | |
| Age, Continuous: Base Study 310 (NCT00477295, n=583) | years | 37.1 (SD 16.33) | 35.6 (SD 15.50) | 36.35 (SD 15.92) |
| Age, Continuous: Extension Study 314 (NCT00848549, n=295) | years | 37.8 (SD 16.13) | 34.4 (SD 14.93) | 36.1 (SD 15.53) |
| Sex/Gender, Customized: Female (Base Study 310, NCT00477295) | participants | 107 | 128 | 235 |
| Sex/Gender, Customized: Male (Base Study 310, NCT00477295) | participants | 174 | 172 | 346 |
| Sex/Gender, Customized: Female (Extension Study 314, NCT00848549) | participants | 57 | 59 | 116 |
| Sex/Gender, Customized: Male (Extension Study 314, NCT00848549) | participants | 80 | 99 | 179 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants Remaining in the Study at Each Visit, measured over At 3, 6, 9, 12, 15, 18, 21, 24, and 27 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Percentage of Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants remaining in the study at each visit. The registry definition specifies that retention is assessed at scheduled visits from 3 through 27 months and that the starting point is the first dose of study drug in the extension phase. The primary-outcome population is defined as all subjects who received at least one dose of investigational product.
Retention is useful in a long-term study because it describes whether participants continue to be followed over time. It can provide context for the availability of later observations and show how participation changes across scheduled visits. It does not, by itself, identify why a participant leaves. A lower retention percentage could reflect different reasons, and the endpoint alone cannot distinguish lack of efficacy, adverse events, participant choice, or other causes.
That distinction matters because the registry separately lists time to drop-out due to lack of efficacy and time to drop-out due to an adverse event. Those outcomes could add information about reasons for leaving, but their results are not reported in the registry record. Retention is also not itself a direct measure of seizure frequency, seizure freedom, or quality of life. The registry lists seizure-free periods and QOLIE-31-P change as secondary outcomes, but does not report their results in the information available for this analysis.
The outcome is expressed as a percentage, with a 95% confidence interval specified as the dispersion measure. A confidence interval generally describes the statistical uncertainty around an estimate; it does not guarantee that the true value lies within the interval. The visit-specific retention percentages and confidence intervals are not reported in the registry record, so the level and precision of retention at individual visits cannot be interpreted from the outcome definition alone.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies retention as the primary outcome and specifies assessments at 3, 6, 9, 12, 15, 18, 21, 24, and 27 months. It also defines the population for that outcome as participants who received at least one dose of investigational product. However, visit-specific retention percentages, confidence intervals, and a treatment-group comparison are not reported in the registry record. Consequently, the available information does not support a numerical interpretation of retention over time or a comparison of the two treatments for the primary outcome.
The outcome name and definition describe what was intended to be measured, not what was observed. A planned assessment schedule is not a result. Without estimates at the visits, it is not possible to describe the pattern of retention, the uncertainty around those estimates, or whether any difference between treatment groups was compatible with chance. No inferential analysis for the primary outcome is reported in the registry record.
The study also lists secondary outcomes that could address different questions: time to drop-out due to lack of efficacy, time to drop-out due to an adverse event, a consecutive seizure-free period of at least 24 months in the base study and extension phase, and change from baseline in QOLIE-31-P overall score at each visit. Their results are not reported in the registry record. Their names alone do not show whether participants experienced a particular outcome or whether the treatment groups differed.
The registry does contain adverse-event counts for extension-study and base-study groups. These are descriptive safety figures, not estimates of efficacy and not a substitute for the primary retention results. The counts should be read within their stated study and treatment groups. They do not establish a causal explanation for retention or drop-out, and the registry record does not report the analysis methods needed to make adjusted comparisons.
Confidence intervals, when reported, would help readers assess precision. In general, a wider interval indicates greater uncertainty about the estimate, while a narrower interval indicates greater precision, subject to the assumptions of the analysis. A confidence interval is not a measure of clinical importance and does not by itself settle whether groups differ. Since the primary endpoint’s percentages and intervals are not reported in the registry record, none of these features can be evaluated for retention.
Overall, the registry record establishes the study question, design, endpoint definition, and some safety counts. It does not report the primary endpoint results or the listed secondary outcome results in the information available for this analysis. Any conclusion about comparative retention, efficacy, or the meaning of changes over time would therefore go beyond the reported results.
9. Statistical Methods Explained
The registry record describes a randomized, double-blind, parallel Phase 3 study. These terms describe aspects of design, not the statistical results. Randomization generally aims to distribute participant characteristics across treatment groups without systematic selection. Double blinding generally limits the influence of knowledge about assigned treatment on participants and study staff. A parallel design compares groups that remain assigned to their respective treatments. The specific procedures used for randomization and blinding are not reported in the registry record.
What does a percentage at each visit represent?
The primary outcome is the percentage of participants remaining in the study at each scheduled visit. In general, a percentage expresses a count relative to a defined group. For this endpoint, the registry definition starts observation from the first dose of study drug in the extension phase. The denominator and handling of participants with incomplete follow-up at each visit are not further described in the registry record. Without that detail and the visit-specific values, it is not possible to reconstruct or evaluate the estimates.
Repeated visit assessments describe retention at multiple times rather than one single endpoint value. As a general statistical matter, observations from the same participant across visits are related, so methods that compare patterns over time may need to account for that dependence. The registry record does not report whether the analysis used a repeated-measures model, separate estimates at each visit, or another approach. It also does not report whether the treatment comparison was adjusted for any other factors.
How should the confidence interval be read?
The endpoint specifies a 95% confidence interval. In general, a confidence interval presents a range of values compatible with the data and the assumptions of the method, and communicates uncertainty around an estimate. It is not a guarantee that the interval contains the true value, nor does it say whether a difference is important in practice. The interpretation also depends on how the estimate was calculated and on the quality of the data. The registry record does not give the visit-specific intervals or the method used to calculate them.
For a treatment comparison, readers would usually want an estimate of the difference between groups, together with its uncertainty, rather than judging the groups only by whether their separate intervals overlap. The registry record does not report a primary-outcome comparison estimate or its confidence interval. Therefore, no conclusion about comparative retention or precision can be drawn from the endpoint description.
What does the safety count describe?
The safety record provides the numbers at risk and the numbers affected for serious and other adverse events in four named groups. These counts are descriptive. General interpretation of adverse-event counts depends on the group definitions, observation time, event definitions, and completeness of reporting. Those details are not all specified in the registry record. The extension-study groups and the base-study groups refer to different study records and should be interpreted separately. Counts alone do not establish that a treatment caused an event or quantify comparative risk after accounting for follow-up.
The listed serious-event terms and percentages are a registry listing, not a complete description of all possible safety outcomes. The record does not provide the methods for selecting or ranking those terms, nor does it report a treatment-adjusted analysis. Death counts are not reported in the registry record.
What are planning illustrations?
Planning sample sizes are hypothetical illustrations of what might be needed under stated assumptions; they are not observed results and are not “observed power.” The assumptions described for the illustrations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is a stated fraction of the observed effect. For non-time-to-event outcomes, the illustrations refer to participants per arm; for time-to-event outcomes, they refer to the total number of events using the Schoenfeld method.
These assumptions do not establish the trial’s original design rationale. The sample-size justification for this trial is not reported in the registry record. The actual planning-illustration values and any corresponding calculations are not reported in the registry information described for this analysis, so no sample-size conclusion can be drawn from the assumptions alone. A planning illustration should not be confused with the number enrolled, the number observed at a visit, or evidence that the study had adequate precision for a particular result.
More broadly, statistical interpretation requires the outcome values, a clear analysis population, handling of missing observations, and a prespecified or otherwise documented analysis approach. The registry record identifies the primary population definition and outcome, but does not report the visit-specific results or a statistical analysis plan. These gaps limit evaluation of both the estimated retention and the uncertainty around it.
10. Multiplicity, Missing Data and Analysis Populations
The study lists several outcomes: retention at multiple scheduled visits, time to drop-out due to lack of efficacy, time to drop-out due to an adverse event, a consecutive seizure-free period, and change in QOLIE-31-P overall score at each visit. When many outcomes or time points are examined, the chance of finding an apparently notable result by chance can increase. General approaches to this issue include identifying a primary comparison in advance, adjusting for multiple testing, or treating additional analyses as exploratory. The registry record does not report a multiplicity strategy or the planned order of testing.
The primary endpoint itself is assessed at 3, 6, 9, 12, 15, 18, 21, 24, and 27 months. These repeated assessments raise questions about whether the intended interpretation concerns each visit separately or an overall pattern over time. The statistical analysis plan and the method for handling multiple visits are not reported in the registry record. The listed secondary outcomes also have no reported results in the information available for this analysis.
The endpoint population is defined as participants who received at least one dose of investigational product. That definition does not explain how missing visit data were handled. The registry record does not report whether participants with incomplete follow-up were excluded from particular visit estimates, treated as no longer retained, or handled by another method. It also does not report imputation procedures, sensitivity analyses, or reasons for missing observations. These choices can affect estimates, especially when missingness is related to treatment experience or outcome status.
The record reports zero analyses in the registry information summarized for this trial. A statistical analysis plan, interim analyses, and sample-size justification are not reported in the registry record. Without those details and the endpoint results, it is not possible to assess how multiplicity or missing data may have influenced the reported evidence.
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 |
|---|---|---|---|
| Zonisamide (Extension Study 314, NCT00848549) | 7 | 137 | 5.1% |
| Carbamazepine (Extension Study 314, NCT00848549) | 7 | 158 | 4.4% |
| Zonisamide (Base Study 310, NCT00477295) | 15 | 281 | 5.3% |
| Carbamazepine (Base Study 310, NCT00477295) | 17 | 300 | 5.7% |
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 |
|---|---|
| Zonisamide (Extension Study 314, NCT00848549) | 12 of 137 |
| Carbamazepine (Extension Study 314, NCT00848549) | 10 of 158 |
| Zonisamide (Base Study 310, NCT00477295) | 72 of 281 |
| Carbamazepine (Base Study 310, NCT00477295) | 69 of 300 |
Most frequent serious adverse event terms
| Event term | Organ system | Zonisamide (Extension Study 314, NCT00848549) | Carbamazepine (Extension Study 314, NCT00848549) | Zonisamide (Base Study 310, NCT00477295) | Carbamazepine (Base Study 310, NCT00477295) |
|---|---|---|---|---|---|
| Partial seizures with secondary generalization | Nervous system disorders | 0 of 137 | 0 of 158 | 0 of 281 | 4 of 300 |
| Facial bones fracture | Injury, poisoning and procedural complications | 0 of 137 | 0 of 158 | 0 of 281 | 2 of 300 |
| Rash | Skin and subcutaneous tissue disorders | 0 of 137 | 0 of 158 | 0 of 281 | 2 of 300 |
| Abdominal pain | Gastrointestinal disorders | 1 of 137 | 0 of 158 | 0 of 281 | 0 of 300 |
| Duodenal ulcer haemorrhage | Gastrointestinal disorders | 1 of 137 | 0 of 158 | 0 of 281 | 0 of 300 |
| Peptic ulcer haemorrhage | Gastrointestinal disorders | 1 of 137 | 0 of 158 | 0 of 281 | 0 of 300 |
| Ataxia | Nervous system disorders | 0 of 137 | 1 of 158 | 0 of 281 | 0 of 300 |
| Carotid artery stenosis | Nervous system disorders | 1 of 137 | 0 of 158 | 0 of 281 | 0 of 300 |
| Somnolence | Nervous system disorders | 0 of 137 | 1 of 158 | 0 of 281 | 0 of 300 |
| Transient ischaemic attack | Nervous system disorders | 1 of 137 | 0 of 158 | 0 of 281 | 0 of 300 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Zonisamide (Extension Study 314, NCT00848549) | Carbamazepine (Extension Study 314, NCT00848549) | Zonisamide (Base Study 310, NCT00477295) | Carbamazepine (Base Study 310, NCT00477295) |
|---|---|---|---|---|---|
| Headache | Nervous system disorders | 6 of 137 | 10 of 158 | 29 of 281 | 37 of 300 |
| Somnolence | Nervous system disorders | 0 of 137 | 0 of 158 | 17 of 281 | 23 of 300 |
| Dizziness | Nervous system disorders | 0 of 137 | 0 of 158 | 11 of 281 | 23 of 300 |
| Weight Decreased | Investigations | 8 of 137 | 0 of 158 | 19 of 281 | 0 of 300 |
| Decreased appetite | Metabolism and nutrition disorders | 0 of 137 | 0 of 158 | 22 of 281 | 5 of 300 |
Serious events with the highest arm-level rate: partial seizures with secondary generalization (1.3%), abdominal pain (0.7%), duodenal ulcer haemorrhage (0.7%), peptic ulcer haemorrhage (0.7%), carotid artery stenosis (0.7%).
The registry lists serious and other adverse-event counts for the extension study and the base study. In the extension study, the zonisamide group had 137 participants at risk for serious adverse events and 7 affected; the carbamazepine group had 158 at risk and 7 affected. For other adverse events, the corresponding figures were 137 at risk and 12 affected for zonisamide, and 158 at risk and 10 affected for carbamazepine.
For Base Study 310, the zonisamide group had 281 participants at risk for serious adverse events and 15 affected; the carbamazepine group had 300 at risk and 17 affected. For other adverse events, the figures were 281 at risk and 72 affected for zonisamide, and 300 at risk and 69 affected for carbamazepine. These base-study figures should be kept distinct from the extension-study figures.
The registry also lists serious-event terms with percentages: partial seizures with secondary generalization, 1.3%; abdominal pain, 0.7%; duodenal ulcer haemorrhage, 0.7%; peptic ulcer haemorrhage, 0.7%; carotid artery stenosis, 0.7%; and transient ischaemic attack, 0.7%. The registry information does not assign those listed percentages to a treatment group. Deaths are not reported in the registry record.
These counts are descriptive and do not, on their own, establish causation or provide a complete comparison of safety. Follow-up duration and other details needed to interpret event occurrence are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The study was designed to assess long-term safety and tolerability and to explore long-term efficacy of zonisamide as monotherapy in newly diagnosed partial seizures. Its primary endpoint measured retention at scheduled visits in the extension phase. The registry record specifies the outcome definition, assessment schedule, and ITT population definition, but does not report the visit-specific retention estimates or confidence intervals in the information available for this analysis.
That absence is important for interpretation. The endpoint description cannot show how many participants remained at any particular visit, whether retention changed over time, or whether the treatment groups differed. It also cannot establish the precision of any estimate. The secondary outcome names do not provide evidence about seizure-free periods, drop-out reasons, or quality of life, because those results are not reported in the registry record.
The adverse-event information provides counts for serious and other events in extension-study and base-study groups. These data can be read as descriptive counts within their recorded groups, but they are not the primary retention result and do not explain why participants remained or left. The listed safety counts do not by themselves establish that a treatment caused an event or that one treatment had a more favorable safety profile.
More generally, a statistical result describes evidence under an analysis and its assumptions; it does not automatically establish a causal or clinically meaningful effect. Randomization and blinding are design features, but the available registry information does not include the outcome estimates and analysis details needed to evaluate comparative results. The sample-size assumptions for planning illustrations also do not provide observed evidence or establish that the trial’s original design was adequate.
The most defensible interpretation is limited: the record describes a randomized, double-blind extension study comparing zonisamide with carbamazepine, identifies retention as the primary outcome, and reports selected safety counts. The registry record does not report the principal endpoint results or the listed secondary efficacy results in the information available for this analysis. No conclusion about comparative efficacy or retention should be inferred from the study objective or design alone.
13. Why This Trial Matters Statistically
This trial is statistically notable because its primary outcome is retention across multiple scheduled visits in a long-term extension study. Retention is relevant to understanding whether participants continue under observation, but it is not a direct measure of seizure control or quality of life. The registry also lists outcomes intended to address drop-out reasons, seizure-free periods, and quality of life, which are conceptually distinct from retention.
Repeated assessments pose an interpretive challenge. A value at an individual visit answers a different descriptive question from an overall comparison of retention patterns across follow-up. General statistical methods may account for the relationship between observations from the same participant, but the registry record does not report the method used. It also does not report visit-specific estimates or a treatment comparison, so the intended question cannot be evaluated from the endpoint definition alone.
The trial also illustrates why a stated endpoint and an observed result must be distinguished. The record defines the primary measure and its confidence-interval type, but does not report the actual retention percentages or intervals in the information available for this analysis. Without these, readers cannot assess magnitude or precision. The secondary outcomes likewise cannot support interpretation without their estimates and methods.
Finally, the safety record contains counts from both the extension study and the base study. Keeping those groups separate is important because they refer to different study records. The figures provide descriptive context, but do not substitute for a comparative safety analysis or the missing primary outcome results. Overall, the statistical value of the record lies in clarifying what was intended to be measured and what information is needed to interpret it—not in establishing comparative treatment effects from the available results.
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 principal limitation for interpreting the primary outcome is that visit-specific retention percentages and their 95% confidence intervals are not reported in the registry record. The record therefore does not permit assessment of the level, pattern, or precision of retention across the scheduled visits, or of a comparison between zonisamide and carbamazepine.
The registry identifies the primary-outcome population as participants who received at least one dose of investigational product, but does not report the number contributing to each visit estimate or how missing visit data were handled. Reasons for missing data and sensitivity analyses are not reported in the registry record. The statistical analysis plan, the method for analyzing repeated visits, and any adjustment for multiple outcomes or time points are also not reported.
The secondary outcomes are named but their results are not reported in the registry information described for this analysis. That includes the time-to-drop-out measures, the consecutive seizure-free-period outcome, and change in QOLIE-31-P overall score. The listed adverse-event counts are descriptive, and details needed to evaluate exposure duration, event ascertainment, or adjusted group comparisons are not reported in the registry record. Deaths are not reported in the registry record.
The safety record includes both extension-study and base-study groups. These are distinct records and should not be combined into a single set of results. The relationship between the base-study participants and the extension population, as well as further details of treatment history and follow-up, is not reported in the registry record. The original sample-size justification and any interim analyses are also not reported. These limitations constrain conclusions about efficacy, retention, and comparative safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Assessing The Long-Term Safety And To Explore The Long-Term Efficacy Of Zonisamide As Monotherapy In Newly Diagnosed Partial Seizures — NCT00848549.
- Registry record last updated 2015-12-24; status last verified 2015-11.
- Results first posted 2013-01-15.
- 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
NCT00848549 is a completed Phase 3 randomized, double-blind, parallel extension study sponsored by Eisai Inc. It enrolled 295 participants and compared zonisamide with carbamazepine as monotherapy for newly diagnosed partial seizures. The study started in 2008-10, and primary completion was in 2011-06.
The primary outcome was the percentage of participants remaining in the study at 3, 6, 9, 12, 15, 18, 21, 24, and 27 months, defined from the first extension-phase dose. The ITT population was defined as all subjects who received at least one dose of investigational product. The registry record also lists secondary outcomes concerning drop-out, seizure-free periods, and quality of life.
Visit-specific primary outcome estimates, confidence intervals, and secondary outcome results are not reported in the registry record in the information available for this analysis. Selected serious and other adverse-event counts are recorded for both the extension study and Base Study 310; they should be interpreted separately. The statistical analysis plan, missing-data procedures, multiplicity strategy, interim analyses, and original sample-size justification are not reported in the registry record.