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 Once-Daily Oral Avatrombopag Tablets Used in Subjects With Chronic Liver Diseases and Thrombocytopenia Prior to Elective Surgical or Diagnostic Procedures (NCT00914927), a randomized phase 2 study. The primary outcome is Percentage of Participants Experiencing Response.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00914927 |
| Phase | Phase 2 |
| Condition | Thrombocytopenia Related to Chronic Liver Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 130 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Eisai Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with chronic liver diseases and thrombocytopenia who were preparing for elective surgical or diagnostic procedures. The registry describes the intent-to-treat population as participants randomized into the study who received study medication and had a posttreatment assessment. It says this population was analyzed as randomized. The registry lists enrollment as 130; that figure is not a count of participants in any particular analysis group.
Intervention
The intervention was once-daily oral avatrombopag, studied for short-term use before the planned procedures. The official title describes use up to 7 days. The safety record lists avatrombopag groups with different doses and formulations across Cohort A and Cohort B. The registry does not provide arm descriptions beyond those safety-group labels.
Comparator
Placebo was the comparator. The safety record includes placebo groups in both Cohort A and Cohort B. The primary-outcome description does not provide a numerical response result for placebo or for any avatrombopag group, so the registry record does not support a reported treatment-versus-placebo estimate for the primary endpoint.
Primary question
The primary endpoint was the percentage of participants experiencing a platelet response by Day 8 (Visit 5, EOT). A response required an increase of at least 20,000/mm^3 from baseline and a platelet count greater than 50,000/mm^3 at least once during Day 4 through Day 8. The registry record does not report a numerical primary-outcome comparison, confidence interval, or test result.
Statistically, the intended question is whether response percentages differ across the randomized treatment groups. The outcome definition combines a change from baseline with a threshold that must be reached during a specified window. That makes the endpoint a binary classification at the participant level, rather than a comparison of average platelet counts alone. The study also set out to evaluate safety and population pharmacokinetics, as stated in its official title. Those additional aims do not replace the primary response question, and their presence does not provide an estimate of the primary treatment contrast.
3. Trial Design
This was a Phase 2, randomized, multicenter, placebo-controlled, double-blind, parallel-group study. Random allocation is intended to make treatment groups comparable on average, while placebo control gives a reference for interpreting outcomes over the same study period. Double masking is intended to limit the influence of treatment knowledge on participant experience, care, outcome assessment, or reporting. These are general design principles; the registry record does not describe the operational masking procedures or how allocation was generated or concealed.
The registry lists enrollment as 130 and status as completed. The start is recorded as 2009-05, and primary completion as 2011-11-11. The intervention was once-daily oral avatrombopag, and the official title describes use up to 7 days before elective surgical or diagnostic procedures. The record includes Cohort A labels for the 1G formulation and Cohort B labels for the 2G formulation. Within those cohorts, the safety groups list different avatrombopag doses and placebo. The arm descriptions themselves are blank, so further details about assignment, dosing schedules, or cohort structure are not reported in the registry record.
The primary outcome was a participant-level platelet response assessed by Day 8 (Visit 5, EOT). The outcome description specifies how repeated platelet measurements within an analysis visit window were selected, including rules based on proximity to the target date and measurement timing. Missing platelet assessments at a given time point were considered non-response at that point and were not estimated. These rules describe outcome handling but do not reveal the numerical response results.
The record does not report the allocation ratio, a sample-size justification, interim analyses, or a detailed statistical analysis plan. It also does not report the primary treatment-effect estimate or its uncertainty. As a result, the registered design can be described, but the primary efficacy comparison cannot be reconstructed from the record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Only the first 6 of 7 groups are shown.
Overall Study
| Stage | Cohort A: 20 mg Avatrombopag, 1G Formulation | Cohort A: 40 mg Avatrombopag, 1G Formulation | Cohort A: 80 mg Avatrombopag, 1G Formulation | Cohort A: Placebo, 1G Formulation | Cohort B: 0 mg Avatrombopag, 2G Formulation | Cohort B: 20 mg Avatrombopag, 2G Formulation |
|---|---|---|---|---|---|---|
| STARTED | 18 | 16 | 17 | 16 | 21 | 21 |
| COMPLETED | 16 | 14 | 17 | 14 | 19 | 21 |
| NOT COMPLETED | 2 | 2 | 0 | 2 | 2 | 0 |
Reasons for not completing this period:
| Reason | Cohort A: 20 mg Avatrombopag, 1G Formulation | Cohort A: 40 mg Avatrombopag, 1G Formulation | Cohort A: 80 mg Avatrombopag, 1G Formulation | Cohort A: Placebo, 1G Formulation | Cohort B: 0 mg Avatrombopag, 2G Formulation | Cohort B: 20 mg Avatrombopag, 2G Formulation |
|---|---|---|---|---|---|---|
| Adverse Event | 0 | 0 | 0 | 0 | 1 | 0 |
| Withdrawal by Subject | 0 | 1 | 0 | 1 | 0 | 0 |
| Lost to Follow-up | 0 | 0 | 0 | 1 | 0 | 0 |
| Administrative/Other | 2 | 1 | 0 | 0 | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-treat (ITT) population included all participants who were randomized into the study, received study medication, and had a posttreatment assessment. The ITT population was analyzed as randomized.
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: Intent to Treat (ITT) population included all participants who were randomized into the study, received study medication, and had a post-treatment assessment.
Only the first 6 of 8 groups are shown.
| Characteristic | Unit | Cohort A: 20 mg Avatrombopag, 1G Formulation | Cohort A: 40 mg Avatrombopag, 1G Formulation | Cohort A: 80 mg Avatrombopag, 1G Formulation | Cohort A: Placebo, 1G Formulation | Cohort B: 10 mg Avatrombopag, 2G Formulation | Cohort B: 20 mg Avatrombopag, 2G Formulation |
|---|---|---|---|---|---|---|---|
| Participants analysed | 18 | 16 | 17 | 16 | 21 | 21 | |
| Age, Continuous | Years | 55.3 (SD 7.16) | 52.8 (SD 7.78) | 55.2 (SD 5.96) | 54.2 (SD 6.87) | 53.9 (SD 5.48) | 56.8 (SD 6.46) |
| Sex: Female, Male: Female | Participants | 4 | 3 | 6 | 5 | 10 | 7 |
| Sex: Female, Male: Male | Participants | 14 | 13 | 11 | 11 | 11 | 14 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants Experiencing Response, measured over Day 8 (Visit 5, EOT).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants experiencing a platelet response by Day 8 (Visit 5, EOT). A responder had to meet both parts of the definition: an increase of at least 20,000/mm^3 in platelet count from baseline, and a platelet count greater than 50,000/mm^3 at least once during Day 4 through Day 8. The endpoint therefore converts repeated platelet measurements into a yes-or-no participant-level outcome.
This kind of endpoint can be useful when the clinical question concerns whether participants reach a prespecified level of change and count during a relevant period. It reflects both improvement relative to baseline and crossing an absolute threshold. It is not the same as comparing mean platelet counts: participants with different measurement patterns can receive the same responder classification if they meet the definition, while participants just short of either requirement are classified as nonresponders.
As a general statistical point, a binary endpoint is often summarized as the number or percentage of participants meeting the response definition in each group, with a treatment contrast and an uncertainty interval. The registry record does not report those primary response counts or a comparison estimate. It therefore documents what response meant, but does not establish the observed size or precision of any difference between groups.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record gives a clear operational definition for the primary response endpoint but does not report the outcome comparison. It lists the endpoint as the percentage of participants experiencing response by Day 8 (Visit 5, EOT), and describes the required platelet-count change and threshold. However, the record reports zero analyses for the posted outcome data, and the primary outcome is not reduced to a single comparison because it has several categories or time points. No numerical response percentage, group contrast, confidence interval, or p-value is reported in the registry record. Consequently, the primary efficacy result cannot be interpreted quantitatively from this record.
The study was randomized, double-blind, placebo-controlled, and parallel-group. Those design features are relevant to how a comparison would be interpreted, but they do not substitute for the comparison itself. Randomization can support a causal interpretation when the study is properly conducted and analyzed; masking can help limit biases related to treatment awareness. Yet without reported group outcomes and an estimate of uncertainty, readers cannot assess the direction, magnitude, or precision of the primary contrast from this record.
The safety record does contain counts for serious and other adverse events by labeled group, as well as a death count for each group. These are descriptive figures and should be read separately from the primary platelet-response endpoint. They do not supply an efficacy estimate or a complete account of the balance of benefits and harms. The registry lists serious-event terms with percentages, but does not provide enough context in this record to attribute those terms to specific groups or to compare their risks reliably.
As a general statistical principle, an estimate describes the observed effect, while its confidence interval describes the range of effect values compatible with the data under the analysis assumptions. A narrow interval would indicate greater precision than a wide interval; neither the interval nor an estimate is reported for the primary endpoint. A p-value, if reported, would address compatibility with a specified null model and would not itself measure clinical importance. No primary-outcome p-value appears in the registry record.
The registry includes a planning-illustration assumption based on an observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation. Such illustrations are not a report of observed power and should not be mistaken for the original trial’s design justification. The sample-size justification and protocol-level planning rationale are not reported in the registry record. With the primary comparison absent, the descriptive design information and safety counts remain informative, but they do not support a numerical conclusion about the primary response contrast.
9. Statistical Methods Explained
What does the endpoint classify?
The primary outcome is binary at the participant level: a participant either meets the response definition or does not. The definition requires an increase of at least 20,000/mm^3 from baseline and a platelet count greater than 50,000/mm^3 at least once during Day 4 through Day 8. The endpoint is reported as a percentage of participants, rather than as a mean change in platelet count. This distinction matters because a response percentage focuses on crossing the stated criteria, whereas a mean summarizes the scale of measurements across participants.
As a general statistical explanation, binary outcomes are often described using event counts and proportions in each group. A treatment comparison might be expressed as a difference or ratio of those proportions, alongside an uncertainty interval. Each summary answers a different question and has different interpretive properties. The registry record does not report primary outcome group counts, a comparative effect estimate, or an interval, so no such interpretation can be made for this trial from the registered results.
How do randomization and masking affect interpretation?
Randomization assigns participants to study groups by chance, with the aim of reducing systematic differences between groups at baseline. It does not guarantee that all characteristics will be identical, especially in a study of limited size. The registry identifies the allocation as randomized but does not report the allocation sequence method, concealment procedure, or group allocation counts for the primary analysis.
Double masking means the record identifies the study as blinded, but the specific people kept unaware of treatment assignment and the procedures used to maintain masking are not reported. As a general principle, masking can reduce the chance that knowledge of treatment affects behavior, care, outcome assessment, or reporting. These design features strengthen the framework for an interpretable comparison, but the result still depends on the actual outcome data and analysis. Those primary comparison results are not reported in the registry record.
How should the confidence interval and test be read?
As a general statistical explanation, a confidence interval expresses uncertainty around an estimated treatment contrast. Its width reflects precision under the model and analysis assumptions; an interval that spans a broad range is less precise than a narrow one. A confidence interval is not a guarantee that the true effect lies within its limits. A hypothesis test and p-value address compatibility between the data and a specified null hypothesis, rather than the clinical importance of an effect. Neither a primary effect estimate, confidence interval, nor test result is reported in this record.
For a percentage endpoint, uncertainty depends on the number of participants with usable outcome information and how the response is distributed across groups. The record describes an intent-to-treat population definition, but does not give primary response counts or group denominators. It is therefore not possible to assess the precision of the response percentages from the registered outcome information.
What does the sample-size illustration represent?
The record describes a planning illustration based on the observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation. Its stated purpose is to illustrate the sample size needed to detect a fraction of the observed effect. This is a planning exercise, not the trial’s reported design rationale. Sample-size illustrations are not observed power: they describe hypothetical planning under assumptions, rather than the probability that the completed study detected an effect after the data were observed.
The original sample-size justification is not reported in the registry record. The record also does not report an interim-analysis plan or a detailed analysis plan. Without those details, the illustration should not be treated as evidence about what the investigators planned before enrollment or about whether the study was adequately sized for its primary question.
Why do measurement and missingness rules matter?
The endpoint description specifies rules for choosing among multiple platelet measurements in the same analysis visit window. The measurement closer to the target date was selected; if measurements were equally distant, the later measurement was selected; and if measurements occurred on the same day, a baseline record used the largest value while a postbaseline record used the smallest. These rules aim to make the selected measurement consistent when more than one measurement is available in a window. The registry record does not report how often the rules affected selection.
Missing platelet assessments at a given time point were treated as non-response at that point and were not estimated. As a general statistical point, this approach makes missingness part of the outcome classification rather than filling in an unobserved measurement. Its consequences depend on how much data are missing and why they are missing. Those details are not reported in the registry record. The rule is clear, but the amount and pattern of missing outcome data cannot be assessed from the record.
10. Multiplicity, Missing Data and Analysis Populations
The record names several secondary outcomes, including change in platelet count on Day 8, dose-response by visit, and the percentages achieving specified platelet-count thresholds on Day 4 or on Days 4 and 8. The primary endpoint itself is described using a Day 4 through Day 8 response window. Considering multiple outcomes, time points, or comparisons can raise multiplicity concerns: as a general statistical principle, making many tests can increase the chance of at least one apparently unusual result if no adjustment or prespecified hierarchy is used. The registry record does not report a multiplicity strategy, a hierarchy among outcomes, or a detailed statistical analysis plan. It is therefore not possible to determine how multiplicity was handled.
The primary endpoint rules state that a missing platelet assessment at any given time point was considered a non-response at that point and was not estimated. The outcome description also gives rules for selecting a platelet measurement when more than one fell in an analysis visit window. These definitions tell readers how missing assessments and repeated measurements were handled at the level of the endpoint. The amount and pattern of missingness, and the effect of these rules on the reported response results, are not reported in the registry record.
The intent-to-treat population is defined as participants who were randomized, received study medication, and had a posttreatment assessment, with analysis as randomized. This definition is more specific than an all-randomized population because it requires study medication and a posttreatment assessment. The record does not report the numbers meeting those criteria in each group for the primary outcome. It also does not describe other analysis populations or sensitivity analyses. Thus, the population rule is available, but the extent to which missingness or exclusions affected the analysis cannot be evaluated from 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 |
|---|---|---|---|
| Cohort A: 20 mg Avatrombopag, 1G Formulation | 3 | 18 | 16.7% |
| Cohort A: 40 mg Avatrombopag, 1G Formulation | 2 | 16 | 12.5% |
| Cohort A: 80 mg Avatrombopag, 1G Formulation | 3 | 17 | 17.6% |
| Cohort A: Placebo, 1G Formulation | 1 | 16 | 6.2% |
| Cohort B: 10 mg Avatrombopag, 2G Formulation | 5 | 21 | 23.8% |
| Cohort B: 20 mg Avatrombopag, 2G Formulation | 3 | 21 | 14.3% |
| Cohort B: Placebo, 2G Formulation | 3 | 21 | 14.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cohort A: 20 mg Avatrombopag, 1G Formulation | 0 of 18 |
| Cohort A: 40 mg Avatrombopag, 1G Formulation | 0 of 16 |
| Cohort A: 80 mg Avatrombopag, 1G Formulation | 0 of 17 |
| Cohort A: Placebo, 1G Formulation | 0 of 16 |
| Cohort B: 10 mg Avatrombopag, 2G Formulation | 1 of 21 |
| Cohort B: 20 mg Avatrombopag, 2G Formulation | 0 of 21 |
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 |
|---|---|
| Cohort A: 20 mg Avatrombopag, 1G Formulation | 17 of 18 |
| Cohort A: 40 mg Avatrombopag, 1G Formulation | 13 of 16 |
| Cohort A: 80 mg Avatrombopag, 1G Formulation | 13 of 17 |
| Cohort A: Placebo, 1G Formulation | 12 of 16 |
| Cohort B: 10 mg Avatrombopag, 2G Formulation | 17 of 21 |
| Cohort B: 20 mg Avatrombopag, 2G Formulation | 18 of 21 |
Most frequent serious adverse event terms
| Event term | Organ system | Cohort A: 20 mg Avatrombopag, 1G Formulation | Cohort A: 40 mg Avatrombopag, 1G Formulation | Cohort A: 80 mg Avatrombopag, 1G Formulation | Cohort A: Placebo, 1G Formulation | Cohort B: 10 mg Avatrombopag, 2G Formulation | Cohort B: 20 mg Avatrombopag, 2G Formulation |
|---|---|---|---|---|---|---|---|
| Liver disorder | Hepatobiliary disorders | 0 of 18 | 0 of 16 | 1 of 17 | 0 of 16 | 1 of 21 | 0 of 21 |
| Cellulitis | Infections and infestations | 0 of 18 | 0 of 16 | 0 of 17 | 1 of 16 | 1 of 21 | 0 of 21 |
| Anaemia | Blood and lymphatic system disorders | 1 of 18 | 0 of 16 | 0 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Gastric haemorrhage | Gastrointestinal disorders | 0 of 18 | 0 of 16 | 1 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Upper gastrointestinal haemorrhage | Gastrointestinal disorders | 1 of 18 | 0 of 16 | 0 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Portal vein thrombosis | Hepatobiliary disorders | 0 of 18 | 0 of 16 | 1 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Pneumonia | Infections and infestations | 1 of 18 | 0 of 16 | 0 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Intentional overdose | Injury, poisoning and procedural complications | 1 of 18 | 0 of 16 | 0 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Seroma | Injury, poisoning and procedural complications | 0 of 18 | 1 of 16 | 0 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
| Acute prerenal failure | Renal and urinary disorders | 0 of 18 | 1 of 16 | 0 of 17 | 0 of 16 | 0 of 21 | 0 of 21 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cohort A: 20 mg Avatrombopag, 1G Formulation | Cohort A: 40 mg Avatrombopag, 1G Formulation | Cohort A: 80 mg Avatrombopag, 1G Formulation | Cohort A: Placebo, 1G Formulation | Cohort B: 10 mg Avatrombopag, 2G Formulation | Cohort B: 20 mg Avatrombopag, 2G Formulation |
|---|---|---|---|---|---|---|---|
| Nausea | Gastrointestinal disorders | 1 of 18 | 2 of 16 | 2 of 17 | 2 of 16 | 5 of 21 | 2 of 21 |
| Headache | Nervous system disorders | 2 of 18 | 2 of 16 | 1 of 17 | 2 of 16 | 1 of 21 | 3 of 21 |
| Fatigue | General disorders | 4 of 18 | 1 of 16 | 0 of 17 | 1 of 16 | 2 of 21 | 2 of 21 |
| Portal hypertensive gastropathy | Gastrointestinal disorders | 4 of 18 | 2 of 16 | 0 of 17 | 0 of 16 | 3 of 21 | 0 of 21 |
| Varices oesophageal | Gastrointestinal disorders | 2 of 18 | 2 of 16 | 0 of 17 | 1 of 16 | 1 of 21 | 2 of 21 |
| Dizziness | Nervous system disorders | 2 of 18 | 0 of 16 | 1 of 17 | 1 of 16 | 3 of 21 | 1 of 21 |
| Diarrhoea | Gastrointestinal disorders | 2 of 18 | 1 of 16 | 1 of 17 | 0 of 16 | 0 of 21 | 3 of 21 |
| Vomiting | Gastrointestinal disorders | 1 of 18 | 2 of 16 | 3 of 17 | 0 of 16 | 0 of 21 | 1 of 21 |
| Procedural pain | Injury, poisoning and procedural complications | 1 of 18 | 2 of 16 | 2 of 17 | 0 of 16 | 1 of 21 | 1 of 21 |
| Muscle spasms | Musculoskeletal and connective tissue disorders | 1 of 18 | 1 of 16 | 2 of 17 | 0 of 16 | 2 of 21 | 1 of 21 |
Serious events with the highest arm-level rate: cellulitis (6.2%), seroma (6.2%), acute prerenal failure (6.2%), gastric haemorrhage (5.9%), liver disorder (5.9%).
The safety record presents serious adverse events, other adverse events, and deaths by labeled treatment group. For example, Cohort A’s 20 mg avatrombopag, 1G formulation group lists 3 participants affected by serious adverse events among 18 at risk, and 17 affected by other adverse events among 18 at risk. The Cohort A placebo, 1G formulation group lists 1 affected by serious adverse events among 16 at risk and 12 affected by other adverse events among 16 at risk. The other groups have their own at-risk and affected counts; these should be read within their respective cohort and formulation labels, not combined into a single comparison.
The death counts are listed by group. Cohort B’s 10 mg avatrombopag, 2G formulation group lists 1 death, while the other listed groups report 0. These counts are descriptive. The record does not establish that a treatment caused an event, and differences between group counts alone do not adjust for chance variation or other factors.
The listed serious-event terms include Cellulitis and Seroma, each at 6.2%, and Acute prerenal failure at 6.2%; Gastric haemorrhage, Liver disorder, and Portal vein thrombosis are each listed at 5.9%. The record does not make clear in this information how those terms map to treatment groups or provide the context needed for group-specific comparisons. Serious adverse-event counts should therefore not be interpreted as complete comparative safety estimates.
12. What the Result Does, and Does Not, Mean
The registry record establishes what the trial set out to study and how its primary platelet-response endpoint was defined. It describes a randomized, double-blind, placebo-controlled, parallel-group Phase 2 trial of once-daily oral avatrombopag before elective procedures in people with chronic liver diseases and thrombocytopenia. The response criterion required both a change from baseline and a platelet count threshold during the stated time window. Those details let readers understand the intended outcome, but not the observed primary result.
The primary response percentages and comparative estimates are not reported in the registry record. No confidence interval or p-value is reported for that endpoint. It is therefore not possible to state from this record how large a treatment difference was observed, how precisely it was estimated, or whether the posted data favor one group. The absence of a reported comparison is not evidence that groups were the same, and it is not evidence of an effect.
The safety figures provide counts for serious and other adverse events and deaths in the listed groups. They are useful descriptive information, but they do not by themselves establish causation or permit a full comparative assessment. The serious-event terms are listed with percentages, but the record does not specify their group mapping in the information available for interpretation. Safety findings should therefore be kept distinct from the missing primary efficacy comparison.
As a general statistical principle, a trial result is best understood through its estimate, uncertainty, outcome definition, and analysis population together. Design labels such as randomized and double-blind describe methods intended to support a fair comparison; they do not reveal the size or precision of the result. Likewise, sample-size planning illustrations are not observed power and do not replace the results. The registry record is informative about design, endpoint rules, and listed safety counts, but it does not support a quantitative conclusion about the primary treatment contrast.
13. Why This Trial Matters Statistically
This trial illustrates why an endpoint definition and a result estimate are separate pieces of statistical evidence. The primary outcome is defined with a change-from-baseline requirement, an absolute platelet-count threshold, and a specified time window. That makes the clinical question more precise than simply asking whether platelet counts changed. At the same time, without the group response data and treatment contrast, the endpoint definition alone cannot show the magnitude or precision of the observed difference.
The randomized, double-blind, placebo-controlled, parallel-group design is also statistically important. These features are intended to support a comparison that is less vulnerable to systematic group differences and treatment-awareness effects. Their value depends on implementation and on transparent reporting of the analysis. The registry describes the broad design, but does not report allocation details, a sample-size justification, an interim-analysis plan, or a detailed statistical analysis plan.
The registry also shows how outcome rules influence interpretation. Missing platelet assessments were classified as non-response at the relevant time point, and repeated measurements within a visit window were selected using specified rules. These choices affect what is counted as a response and should be considered when comparing results across studies. The record does not report missingness patterns or the primary outcome values needed to assess their impact in this trial.
Finally, the safety counts demonstrate the difference between descriptive event reporting and a comparative analysis. Counts should be interpreted in their labeled groups and with attention to their denominators. They do not establish causality, and they cannot replace a clearly reported efficacy estimate. The central statistical lesson is that study design, endpoint rules, missing-data handling, and result reporting all contribute to interpretation; none alone supplies the absent primary comparison.
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 statistical interpretation is that the registry record does not report numerical results for the primary response endpoint. The outcome is described, but there is no reported group response percentage, treatment contrast, confidence interval, or test result. The registry also indicates that the primary outcome has several categories or time points and was not reduced to a single comparison. This prevents a quantitative interpretation of the main question.
Important analysis details are not reported in the registry record. These include a detailed statistical analysis plan, multiplicity handling, sample-size justification, interim analyses, allocation ratio, and the methods used to generate and conceal the random sequence. The registry does not report the numbers included in the intent-to-treat population by group for the primary outcome, nor does it provide the amount or pattern of missing platelet assessments. Although missing measurements were treated as non-response at the relevant point, the impact of that rule cannot be evaluated without those data.
The arm descriptions are blank, while the safety record names Cohort A and Cohort B groups by formulation, dose, and placebo. Further treatment-administration details are not reported in the registry record. The serious adverse-event terms are listed with percentages, but the information does not specify how those terms map to groups. The safety figures therefore support descriptive reading by labeled group, not a complete comparative safety interpretation.
These limitations concern what can be concluded from the registry record; they do not establish that the study lacked analyses or procedures outside the record. Such details are simply not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Once-Daily Oral Avatrombopag Tablets Used in Subjects With Chronic Liver Diseases and Thrombocytopenia Prior to Elective Surgical or Diagnostic Procedures — NCT00914927.
- Registry record last updated 2018-01-23; status last verified 2018-01.
- Results first posted 2018-01-23.
- 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
NCT00914927 is a completed Phase 2 randomized, multicenter, double-blind, placebo-controlled, parallel-group study of once-daily oral avatrombopag in people with chronic liver diseases and thrombocytopenia before elective surgical or diagnostic procedures. The registry lists enrollment as 130 and primary completion as 2011-11-11. The official title describes treatment for up to 7 days and study aims covering efficacy, safety, and population pharmacokinetics.
The primary endpoint was the percentage of participants meeting a platelet-response definition by Day 8 (Visit 5, EOT). Response required an increase of at least 20,000/mm^3 from baseline and a platelet count greater than 50,000/mm^3 at least once during Day 4 through Day 8. The registry record does not report a numerical primary-outcome comparison. It does list serious and other adverse-event counts and deaths by labeled group, but these are descriptive and do not provide the missing primary efficacy estimate.