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 Telaprevir, Peg-IFN-alfa-2a, and RBV in Treatment-Experienced Black/African American and Non-Black/African American Subjects With Genotype 1 Chronic Hepatitis C (NCT01467492), a non-randomized phase 4 study. The primary outcome is Percentage of Participants With Sustained Viral Response 12 Weeks After Last Actual Dose of Study Drug (SVR12).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01467492 |
| Phase | Phase 4 |
| Condition | Hepatitis C |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 121 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Vertex Pharmaceuticals Incorporated |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned Black/African American and non-Black/African American participants with genotype 1 chronic hepatitis C who had not achieved a sustained viral response after a prior course of interferon-based therapy. The registry describes the population as treatment-experienced. Enrollment was 121, while the safety counts list 82 participants in Group A and 38 in Group B; these figures do not establish the primary endpoint denominators.
Intervention
The regimen combined telaprevir, peginterferon alfa-2a, and ribavirin. The arm descriptions specify telaprevir 750 mg three times per day for 12 weeks, peginterferon alfa-2a 180 mcg/week, and ribavirin dosing based on weight. The non-Black group description specifies treatment for 24 or 48 weeks. The total treatment duration for the Black group is not reported in the registry record.
Comparator
There was no randomized control arm. The study was non-randomized and designated as a single-group model, with groups described by Black/African American and non-Black/African American status. Those groups are not a like-for-like control comparison: the record does not describe random allocation or establish that they differed only by the characteristic used to label them.
Primary question
The primary endpoint was the percentage of participants with a sustained viral response 12 weeks after their last actual dose of study drug. In practical terms, the endpoint asks whether HCV RNA was undetectable at that specified follow-up. The registry defines undetectable as below the assay’s lower limit of quantification. The result by group, its uncertainty, and any formal group comparison are not reported in the registry record.
3. Trial Design
This was an open-label, Phase 4, non-randomized study of telaprevir with peginterferon alfa-2a and ribavirin in treatment-experienced participants with genotype 1 chronic hepatitis C. The record identifies Black/African American and non-Black/African American groups, but describes the study model as single group and does not identify a randomized comparator. Participants and investigators were not masked.
Enrollment was 121. The study started in 2012-01, had primary completion in 2014-05, and is listed as terminated. The reason for termination is not reported in the registry record. The record also does not explain whether all enrolled participants began treatment, completed follow-up, or contributed to each outcome.
The treatment descriptions include telaprevir 750 mg three times per day for 12 weeks, peginterferon alfa-2a 180 mcg/week by subcutaneous injection, and ribavirin taken orally twice daily. Ribavirin dosing was 1000 mg/day for participants weighing <75 kg or 1200 mg/day at the higher weight category. The non-Black group description specifies peginterferon and ribavirin for 24 or 48 weeks. The treatment duration for the Black group beyond the stated telaprevir course is not reported in the registry record.
The stated purpose was to evaluate efficacy and safety in this treatment-experienced population. The primary endpoint was SVR12, with secondary outcomes covering SVR24, extended rapid viral response, relapse, virologic breakthrough, on-treatment virologic failure, adverse events, serious adverse events, and telaprevir-resistant HCV variants. The registry record does not report a statistical analysis plan or a randomized treatment comparison.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: Efficacy analyses were reported as per Race (Black/Non-Black) (reporting arms) and also separately as per prior response (in categories) (Prior Relapser, Prior Null Responder, Prior Partial Responder as well as for Total Participants), unless otherwise specified.
Overall Study
| Stage | Group A - Black | Group B - Non-Black |
|---|---|---|
| STARTED | 83 | 38 |
| COMPLETED | 61 | 25 |
| NOT COMPLETED | 22 | 13 |
Reasons for not completing this period:
| Reason | Group A - Black | Group B - Non-Black |
|---|---|---|
| Withdrawal by Subject | 6 | 4 |
| Study Terminated by Sponsor | 6 | 4 |
| Adverse Event | 4 | 3 |
| Lost to Follow-up | 3 | 2 |
| Undefined | 2 | 0 |
| Enrolled But Not Treated | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: FA Set. Here, n signifies participants who were evaluable for specified category for each arm, respectively.
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: Full Analysis (FA) Set included all enrolled participants who received at least 1 dose of any study drug.
| Characteristic | Unit | Group A - Black | Group B - Non-Black | Total |
|---|---|---|---|---|
| Participants analysed | 82 | 38 | 120 | |
| Age, Continuous | years | 57.7 (SD 5.59) | 55.8 (SD 5.95) | 57.1 (SD 5.76) |
| Sex: Female, Male: Female | Participants | 34 | 6 | 40 |
| Sex: Female, Male: Male | Participants | 48 | 32 | 80 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Sustained Viral Response 12 Weeks After Last Actual Dose of Study Drug (SVR12), measured over 12 weeks after last actual dose of study drug (up to Week 60).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint was the percentage of participants with sustained viral response 12 weeks after the last actual dose of study drug, within a timeframe described as up to Week 60. The registry defines SVR12 as an undetectable HCV RNA level at that follow-up. The assay’s lower limit of quantification was 25 IU/mL, so the endpoint definition concerns RNA below that threshold. HCV RNA was measured using the Roche TaqMan HCV RNA assay.
SVR12 is a binary outcome for each evaluable participant: the endpoint classifies the measured viral RNA result at the specified follow-up as meeting or not meeting the registry’s undetectable criterion. The reported percentage would describe the share meeting that definition in the analysis population. The registry notes that the analysis population is the FA Set and that the number for each category signifies participants evaluable for that category in each arm.
In general, a prespecified follow-up endpoint gives a consistent time point for describing participants’ outcomes after treatment. That can make results easier to interpret than measurements taken at varying times. However, the percentage alone would not convey precision; a confidence interval, if reported, would indicate the range of estimates compatible with the data and analysis. The SVR12 result and its uncertainty are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies SVR12 as the primary endpoint, but does not report the endpoint result, its denominator, or an uncertainty estimate. It therefore does not support a numerical interpretation of the primary efficacy outcome. The record lists a study enrollment of 121, but enrollment is not interchangeable with the number evaluable for SVR12. The primary analysis population is identified as the FA Set, and the record says that category counts refer to evaluable participants for each arm; the arm-specific endpoint counts are not reported in the registry record.
The study’s structure also limits what can be inferred from a comparison between the Black and non-Black groups. Allocation was non-randomized, masking was absent, and the record explicitly cautions that the groups are not a like-for-like control comparison. Any difference between group percentages, if available, could reflect factors beyond the group label or treatment response. The record does not report an adjusted analysis or a method for accounting for differences between groups.
The available safety figures list serious adverse events affecting 7 of 82 participants in Group A - Black and 6 of 38 participants in Group B - Non-Black. Other adverse-event counts are listed as 79 of 82 and 38 of 38, respectively. These are descriptive counts, not evidence of a causal treatment effect. The registry does not provide a randomized untreated or alternative-treatment group against which to interpret them. Death counts are not reported in the registry record.
Several secondary outcomes are named, including SVR24, relapse, virologic breakthrough, on-treatment virologic failure, and adverse events. Naming an outcome is not the same as reporting its result. The record lists nine outcome measures and zero analyses; detailed outcome estimates, confidence intervals, p-values, and formal comparisons are not reported in the registry record.
In general, a confidence interval describes statistical uncertainty around an estimate, while a p-value summarizes how compatible data are with a specified null model under the analysis assumptions. Neither can establish that an effect is clinically important or remove limitations from a non-randomized design. Because the registry does not report the primary estimate or its precision, the magnitude and uncertainty of SVR12 cannot be judged from this record. Sample-size planning illustrations, where available, should not be read as observed power or as trial results.
9. Statistical Methods Explained
What kind of outcome is SVR12?
The primary outcome is a percentage of participants, and the registry’s outcome classification is a percentage with an event. The event for this endpoint is meeting the SVR12 definition: HCV RNA below the assay’s lower limit of quantification at the specified follow-up. Each evaluable participant is classified according to that criterion, and a group percentage describes the share meeting it. The registry identifies the FA Set as the population and explains that the count for each category is based on participants evaluable for that category in each arm.
In general, a binary endpoint reduces each participant’s outcome to a category such as meeting or not meeting a definition. This makes a percentage straightforward to describe, but it does not retain every detail of the underlying measurement. For SVR12, the threshold and timing are therefore central to interpretation. The registry defines the threshold using the assay’s lower limit of quantification, 25 IU/mL, and specifies follow-up 12 weeks after the last actual dose.
What does an uncertainty estimate add?
In general, a confidence interval expresses sampling uncertainty around an estimate under a particular statistical method and its assumptions. A narrow interval indicates greater precision than a wide interval, while neither guarantees that the estimate is free from bias. A p-value addresses compatibility with a specified null hypothesis under an analysis model; it is not the probability that a treatment works, nor does it measure the size or importance of an effect.
The registry does not report the SVR12 estimate, confidence interval, or p-value. It lists zero analyses. Consequently, there is no reported primary endpoint estimate to assess for precision or to use in a statistical comparison. The safety counts do not substitute for an efficacy analysis or an uncertainty interval.
Why does the design affect interpretation?
The study is open-label and non-randomized, and the registry identifies a single-group model. In general, random allocation helps balance both measured and unmeasured characteristics across treatment groups, on average. Without randomization, observed differences between groups can be related to participant characteristics, care, follow-up, or other factors as well as the treatment. Masking can reduce some influences on reporting or assessment; masking was absent in this study.
The Black and non-Black groups are not a randomized treatment comparison. The registry itself cautions that they are not like-for-like controls. A descriptive difference between them would not isolate a causal effect of treatment or of group membership. The record does not report adjustment methods, a comparator arm, or a formal between-group analysis.
What do the planning assumptions mean?
The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Its stated effect to detect is a fraction of the observed effect. These are planning assumptions, not evidence that the trial used that design or that an effect was detected. The record does not report the trial’s own sample-size justification, and it does not provide the endpoint result needed to interpret the observed-effect basis. Any such planning illustration is not observed power and should not be mistaken for a result from the trial.
In general, a sample-size calculation estimates the amount of information a proposed design would need under stated assumptions. It depends on the chosen outcome, target effect, error rates, allocation, and analysis method. If assumptions differ from the actual study or the effect estimate is uncertain, the calculation may not describe the study’s ability to answer its question. The registry’s planning assumptions do not establish that the study was designed around equal randomized groups; the actual allocation is listed as non-randomized.
How should the adverse-event counts be read?
The safety record gives, for each group, the number at risk and the number affected for serious adverse events and for other adverse events. These are counts attached to the listed groups. In general, a count describes how many participants were recorded with an event, while a percentage expresses that count relative to a denominator. The record also lists serious adverse event terms with percentages, but does not identify the denominator for those term-level percentages. They should not be assumed to be rates for each group or compared directly across groups without that information.
Safety counts can inform a description of what was recorded, but they do not by themselves show that the study drug caused an event. The non-randomized design, the absence of a comparator, and the missing denominator details for the term-level percentages constrain comparisons. Definitions and handling of recurrent events are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The record names a primary endpoint, SVR12, and several secondary outcomes: SVR24, extended rapid viral response, relapse, virologic breakthrough, on-treatment virologic failure, adverse events, serious adverse events, and telaprevir-resistant HCV variants. It lists nine outcome measures overall and zero analyses. The results and statistical comparisons for these outcomes are not reported in the registry record.
When a study examines multiple outcomes or makes multiple statistical comparisons, the chance of at least one apparently noteworthy finding can increase. In general, a multiplicity plan may specify which outcomes are confirmatory, how comparisons are ordered, and whether significance thresholds are adjusted. The registry does not report a multiplicity strategy, a hierarchy of secondary outcomes, or an adjustment method. It is therefore not possible to determine whether any reported statistical claims were intended as confirmatory; no such analysis results are listed.
The record identifies the primary analysis population as the FA Set and notes that counts refer to participants evaluable for the specified category in each arm. It does not define the FA Set in further detail in the information available, state how missing endpoint measurements were handled, or explain whether participants without follow-up were included in the denominator. The primary endpoint counts and denominators are not reported in the registry record.
In general, missing outcome data can affect both the denominator and the interpretation of a percentage, especially if participants with missing measurements differ from those with observed measurements. Statistical methods may use explicit assumptions or sensitivity analyses to explore this issue. The registry does not report missing-data assumptions, imputation procedures, or sensitivity analyses. No conclusion about their effect on the SVR12 estimate can be drawn because the estimate and handling methods are not reported.
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 |
|---|---|---|---|
| Group A - Black | 7 | 82 | 8.5% |
| Group B - Non-Black | 6 | 38 | 15.8% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Group A - Black | 79 of 82 |
| Group B - Non-Black | 38 of 38 |
Most frequent serious adverse event terms
| Event term | Organ system | Group A - Black | Group B - Non-Black |
|---|---|---|---|
| Anaemia | Blood and lymphatic system disorders | 0 of 82 | 2 of 38 |
| Dehydration | Metabolism and nutrition disorders | 1 of 82 | 1 of 38 |
| Warm type haemolytic anaemia | Blood and lymphatic system disorders | 1 of 82 | 0 of 38 |
| Abdominal pain | Gastrointestinal disorders | 1 of 82 | 0 of 38 |
| Pancreatitis | Gastrointestinal disorders | 0 of 82 | 1 of 38 |
| Vomiting | Gastrointestinal disorders | 1 of 82 | 0 of 38 |
| Cellulitis | Infections and infestations | 1 of 82 | 0 of 38 |
| Salmonellosis | Infections and infestations | 1 of 82 | 0 of 38 |
| Urinary tract infection | Infections and infestations | 1 of 82 | 0 of 38 |
| Hypokalaemia | Metabolism and nutrition disorders | 1 of 82 | 0 of 38 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Group A - Black | Group B - Non-Black |
|---|---|---|---|
| Anaemia | Blood and lymphatic system disorders | 40 of 82 | 19 of 38 |
| Fatigue | General disorders | 31 of 82 | 26 of 38 |
| Pruritus | Skin and subcutaneous tissue disorders | 33 of 82 | 16 of 38 |
| Nausea | Gastrointestinal disorders | 20 of 82 | 17 of 38 |
| Rash | Skin and subcutaneous tissue disorders | 15 of 82 | 13 of 38 |
| Headache | Nervous system disorders | 14 of 82 | 13 of 38 |
| Influenza like illness | General disorders | 15 of 82 | 7 of 38 |
| Anal pruritus | Gastrointestinal disorders | 16 of 82 | 5 of 38 |
| Insomnia | Psychiatric disorders | 8 of 82 | 10 of 38 |
| Decreased appetite | Metabolism and nutrition disorders | 11 of 82 | 7 of 38 |
Serious events with the highest arm-level rate: anaemia (5.3%), pancreatitis (2.6%), dehydration (2.6%), hypotension (2.6%), angina pectoris (2.6%).
The registry lists serious adverse events affecting 7 of 82 participants in Group A - Black and 6 of 38 participants in Group B - Non-Black. It also lists other adverse events affecting 79 of 82 and 38 of 38 participants, respectively. These are group-specific counts; they are not a randomized comparison and should not be read as establishing that one group had a higher or lower treatment-related risk.
Several serious adverse event terms are listed with percentages: Anaemia, 5.3%; Pancreatitis, 2.6%; Dehydration, 2.6%; Hypotension, 2.6%; Angina pectoris, 2.6%; and Facial bones fracture, 2.6%. The denominator and group attribution for these term-level percentages are not reported in the registry record. The figures should therefore be treated as listed descriptive percentages, not as group-specific rates. The record does not explain whether participants could contribute more than one event or how repeated events were counted.
In general, safety counts describe events recorded during a study, not necessarily events caused by the treatment. There is no randomized comparator in this record to help distinguish treatment-related events from events that would otherwise occur. Death counts are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
This registry record describes a Phase 4 study of telaprevir combined with peginterferon alfa-2a and ribavirin in treatment-experienced participants with genotype 1 chronic hepatitis C. Its primary endpoint is clearly defined as SVR12, based on HCV RNA below the stated assay threshold at the specified follow-up. The record also identifies a range of secondary efficacy and safety outcomes.
However, the primary endpoint result is not reported in the registry record. There is no reported SVR12 percentage, evaluable denominator, confidence interval, or p-value. Therefore, the magnitude of the recorded primary outcome and its statistical precision cannot be assessed from this record. The study’s stated purpose is not itself evidence of an outcome.
The safety information gives affected-participant counts for serious and other adverse events in the two listed groups, alongside a list of serious event terms and percentages. These figures describe what the record reports; they do not establish causation. Because allocation was non-randomized and the groups are not like-for-like controls, they also do not support a direct causal comparison between groups.
In general, an observed percentage is a descriptive estimate for a defined population and follow-up. Its interpretation depends on who was included, how missing measurements were handled, how events were counted, and the uncertainty around the estimate. Several of these details are not reported in the registry record. A planning illustration based on an observed effect, if displayed with the results, would address hypothetical sample-size requirements under its stated assumptions; it would not be an observed trial outcome or a measure of observed power.
The record can establish the study’s listed design, population, endpoint definition, and certain safety counts. It cannot establish from the posted results whether the primary endpoint was met, how precise the outcome was, or whether treatment caused the recorded events. Those conclusions require results and analysis details that are not reported in the registry record.
13. Why This Trial Matters Statistically
This study illustrates why a clearly defined endpoint and a reported result are both needed for statistical interpretation. SVR12 has a specified follow-up point and an assay-based threshold, which make the intended classification understandable. But without the outcome count, denominator, and estimate, readers cannot judge the observed percentage or its precision.
It also illustrates the distinction between a descriptive grouping and a valid control comparison. The record separates participants into Black/African American and non-Black/African American groups, yet allocation is non-randomized and the groups are explicitly not like-for-like controls. A group contrast should not be treated as a treatment effect simply because two groups are listed. In general, design determines what statistical comparisons can support, not just which calculations can be performed.
The record also names multiple outcomes but does not report analyses or a multiplicity approach. In general, selective emphasis among many outcomes can make results difficult to interpret unless outcome priorities and analysis methods are clear. Here, the lack of reported estimates prevents assessment of either primary or secondary outcome findings.
Finally, the safety record shows why denominators and event definitions matter. Group-level counts are available for serious and other adverse events, but the term-level percentages lack a reported denominator and group attribution. Statistical interpretation depends on those details and on the study’s non-randomized structure. The record is therefore useful for understanding the intended question and available descriptive information, while also demonstrating how missing analysis results restrict conclusions.
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 registry lists the study as terminated, but the reason for termination is not reported in the registry record. It is also unclear from the record whether enrollment, treatment, or follow-up ended as planned. The listed enrollment is 121, while the safety groups have their own at-risk counts; the relationship between these figures and the primary endpoint analysis population is not reported.
The non-randomized, open-label design is a major interpretive limitation. The two groups are not a like-for-like control comparison, and the record does not report adjustment for potential differences between them. It consequently does not support attributing group differences to treatment or to the group characteristic alone.
The record does not report the primary endpoint result, its denominator, a confidence interval, or a p-value. It lists zero analyses. The registry also does not report the sample-size justification for the trial, the statistical analysis plan, or a multiplicity procedure. The stated planning assumptions are illustrations rather than evidence of the trial’s original design rationale.
Details that would help assess completeness and possible bias are also absent: the definition of the FA Set beyond the evaluability note, how missing endpoint data were handled, and whether sensitivity analyses were conducted. For safety, the denominator and group attribution of the serious-event term percentages are not reported, and event counting details are not described. Death counts are not reported in the registry record. These gaps limit both efficacy and safety interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Telaprevir, Peg-IFN-alfa-2a, and RBV in Treatment-Experienced Black/African American and Non-Black/African American Subjects With Genotype 1 Chronic Hepatitis C — NCT01467492.
- Registry record last updated 2015-08-03; status last verified 2015-06.
- Results first posted 2015-06-16.
- 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
NCT01467492 is an open-label, non-randomized Phase 4 study of telaprevir, peginterferon alfa-2a, and ribavirin in treatment-experienced Black/African American and non-Black/African American participants with genotype 1 chronic hepatitis C. Enrollment was 121; the study started in 2012-01, reached primary completion in 2014-05, and is listed as terminated.
The primary endpoint was the percentage with SVR12, defined using HCV RNA below the assay’s lower limit of quantification 12 weeks after the last actual dose. The primary result and its precision are not reported in the registry record. Safety counts are available for serious and other adverse events, but the study has no randomized comparator, and term-level serious-event denominator details are absent. The record lists nine outcome measures and zero analyses.