A Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of ABT-450 With Ritonavir (ABT-450/r) When Given Together With ABT-333 and Ribavirin (RBV) in Treatment-Naïve and Non-responder Subjects With Genotype 1 Chronic Hepatitis C Virus (HCV) Infection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of ABT-450 With Ritonavir (ABT-450/r) When Given Together With ABT-333 and Ribavirin (RBV) in Treatment-Naïve and Non-responder Subjects With Genotype 1 Chronic Hepatitis C Virus (HCV) Infection (NCT01306617), a non-randomized phase 2 study. The primary outcome is Percentage of Participants With Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Suppressed Below the Lower Limit of Detection (LLOD) From Week 4 Through Week 12.

2. Clinical Question

The study evaluated antiviral activity, safety, and pharmacokinetics in people with chronic genotype 1 HCV infection. Its groups distinguish treatment-naïve participants from previous non-responders, and the treatment-naïve groups also differ in the ABT-450/r dose. This makes the study relevant to describing outcomes across those enrolled groups, but it does not create a randomized comparison between them.

The primary question is about the proportion reaching a specified viral RNA threshold during treatment, rather than a direct comparison with an untreated or alternative-treatment control. The registry also lists outcomes involving viral RNA at other thresholds or time points, sustained virologic response after treatment, virologic failure or relapse, resistance, and pharmacokinetics. Their results are not reported in the registry record.

3. Trial Design

This was a Phase 2, open-label, non-randomized, parallel-group study. The registry records enrollment of 50 and a completed status. The study began in 2011-02, with primary completion in 2011-11. AbbVie (prior sponsor, Abbott) is listed as the sponsor.

Three treatment groups are described. Treatment-naïve participants received either ABT-450/r (250/100 mg) once daily or ABT-450/r (150/100 mg) once daily, with ABT-333 (400 mg) twice daily and weight-based ribavirin divided twice daily. Both treatment-naïve regimens are described as lasting 12 weeks. Previous non-responders to pegylated interferon and ribavirin received ABT-450/r (150/100 mg) once daily, ABT-333 (400 mg) twice daily, and weight-based ribavirin divided twice daily. The treatment duration for this group is not reported in the registry record.

Open-label means masking was not used, as reflected by the registry’s masking entry. Non-randomized allocation means assignment was not randomized. The record explicitly cautions that the arms are not a like-for-like control comparison. Consequently, observed differences across groups could reflect their different participant histories or other differences, and should not be interpreted as randomized evidence of comparative efficacy.

The primary efficacy population is described as all participants who received at least one dose of study drug, with missing data imputed as failures. Further information about how participants entered each group, the allocation process, or group-specific baseline characteristics is not reported in the registry record. The primary endpoint result and estimates of uncertainty are also not reported in the registry 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Efficacy analyses included all participants who received at least 1 dose of study drug (ITT). Participants with missing data were imputed as failures.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Baseline analyses included all participants.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Suppressed Below the Lower Limit of Detection (LLOD) From Week 4 Through Week 12, measured over Week 4 through Week 12.

The primary endpoint is the percentage of participants with HCV RNA suppressed below the lower limit of detection from Week 4 through Week 12. The registry specifies the threshold as HCV RNA < 15 IU/mL. This is a binary outcome at the participant level: each participant either meets the stated suppression criterion or does not, and the result is expressed as a percentage.

Viral RNA measurement is used to assess the amount of virus detectable in a blood sample. A threshold-based endpoint describes whether measured RNA is below a specified assay limit; it does not mean that no virus exists. The lower limit of detection is distinct from the lower limit of quantitation, which appears in one of the listed secondary outcomes.

As a general statistical point, a percentage is easier to interpret when its denominator and missing-data handling are clear. The registry says the efficacy analysis included all participants who received at least one dose, and that missing data were imputed as failures. The observed percentage, its denominator, and any interval describing uncertainty are not reported in the registry record. Therefore, the endpoint definition is available, but the magnitude and precision of the primary result cannot be assessed from the registry information described.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help clarify what this study’s endpoint and design can establish. The points below distinguish general statistical principles from details stated in the registry record.

What does a percentage endpoint represent?

As a general concept, a binary endpoint classifies each participant according to whether a criterion is met. The percentage is the number meeting the criterion relative to the analysis denominator, expressed as a proportion on a percentage scale. For this study, the criterion is HCV RNA below the lower limit of detection from Week 4 through Week 12, with the threshold stated as < 15 IU/mL. The registry record does not report the resulting percentage or its denominator.

A threshold makes an outcome clinically and analytically interpretable in a particular way, but it also reduces a continuous measurement to a yes-or-no classification. Participants just above and just below a threshold are assigned to different categories, even though their measured values may be close. General interpretation should therefore keep the exact threshold and the underlying measurement context in view. The record does not report assay-performance details or the distribution of measured RNA values.

Why does the design affect comparisons?

As a general principle, random allocation helps balance known and unknown participant characteristics across treatment groups, on average. This trial was non-randomized, and the registry says its arms are not a like-for-like control comparison. Its groups also differ by treatment history and, among treatment-naïve participants, by ABT-450/r dose. A numerical difference between groups would therefore be descriptive unless supported by additional design and analysis information. The registry does not report a randomized comparison.

Parallel groups receive their assigned regimens in separate groups rather than crossing over between regimens, as indicated by the parallel model. The open-label designation means masking was absent. These features describe how the study was organized; they do not, by themselves, tell whether an endpoint was measured accurately or whether an observed difference was caused by treatment.

What does uncertainty around an estimate mean?

As a general statistical explanation, a confidence interval gives a range of values compatible with the data under a specified method and assumptions. It communicates precision as well as the estimated result: a narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. A p-value, when reported, addresses how compatible the data are with a specified statistical null model; it is not a measure of clinical importance or the probability that a treatment works.

The primary endpoint estimate, confidence interval, and p-value are not reported in the registry record. No conclusion about its precision or statistical compatibility with a null hypothesis can therefore be drawn from the endpoint definition alone. The registry also does not report an adjusted comparison for the groups.

Why can missing-data rules matter?

The efficacy analysis included all participants who received at least one dose, described as an intention-to-treat analysis in the registry. Missing endpoint data were imputed as failures. As a general point, an imputation rule substitutes an assumed outcome for an unobserved outcome, allowing an analysis to retain participants without observed endpoint measurements. The resulting estimate depends partly on that assumption. Calling missing values failures is a specific conservative convention in some settings, but it does not guarantee that bias is eliminated; its impact depends on why data are missing and what the unobserved outcomes would have been.

The registry does not report how many observations were missing, why they were missing, or any sensitivity analysis using alternative assumptions. The stated failure imputation is therefore useful context, but it is not enough to judge how robust the endpoint estimate would be to missing-data assumptions.

How should planning calculations be understood?

The registry describes sample-size illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not evidence about the trial’s observed precision, and sample-size illustrations are not observed power. The record does not report the trial’s own sample-size justification or design assumptions.

As a general principle, a planning calculation asks how much information a future study might need under specified assumptions. Its result is conditional on those assumptions, including the effect size used. It should not be confused with a post hoc claim that the completed study had a particular probability of detecting an effect. The numerical outputs of any planning illustration are not reported in the registry record.

For time-to-event outcomes, the registry’s planning description refers to the total number of events; for other outcomes it refers to participants per arm. This distinction reflects different ways of representing information for different outcome types. No time-to-event endpoint estimate or planning output is reported in the registry record.

What can multiple listed outcomes establish?

As a general statistical issue, evaluating many outcomes can increase the chance that at least one result appears notable by chance if no adjustment or prespecified hierarchy is used. The registry lists several secondary virologic, resistance, and pharmacokinetic outcomes. It does not report a multiplicity adjustment, a testing hierarchy, or an account of how conclusions were selected among outcomes. Those analysis details are not reported in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("ABT-450/r (250/100 mg) and ABT-333 Plus RBV in Tre", "ABT-450/r (150/100 mg) and ABT-333 Plus RBV in Tre", "ABT-450/r (150/100 mg) and ABT-333 Plus RBV in Non")
n      <- c(19, 14, 17)
events <- c(17, 11, 10)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  ABT-450/r (250/100 mg) and ABT-333 Plus RBV in Tre  19  17  89.5  66.9  98.7  68.6  97.1  68.3  96.8
ARM  ABT-450/r (150/100 mg) and ABT-333 Plus RBV in Tre  14  11  78.6  49.2  95.3  52.4  92.4  51.9  92.2
ARM  ABT-450/r (150/100 mg) and ABT-333 Plus RBV in Non  17  10  58.8  32.9  81.6  36.0  78.4  35.7  78.5

11. Multiplicity, Missing Data and Analysis Populations

The primary analysis population is described as all participants who received at least one dose of study drug, identified in the registry as the intention-to-treat population. The primary endpoint is the percentage with HCV RNA below the lower limit of detection from Week 4 through Week 12. Participants with missing data were imputed as failures. This tells readers how the registry says missing primary efficacy observations were classified, but it does not reveal how many observations were missing or how sensitive the result was to that decision.

Further information about the handling of missing values for secondary outcomes is not reported in the registry record. The reasons for missingness, the timing of missing observations, and sensitivity analyses are also not reported in the registry record. Without these details, the effect of missing data on reported estimates cannot be assessed.

The registry lists multiple secondary outcomes, including HCV RNA thresholds, sustained virologic response at post-treatment time points, failure to suppress or rebound, relapse, resistance, and pharmacokinetics. A prespecified multiplicity strategy can help control the chance of drawing overly strong conclusions from testing numerous outcomes. Such a strategy, including any testing hierarchy or adjustment, is not reported in the registry record. The number of listed outcome measures and analyses does not by itself establish how the analyses were conducted or interpreted.

Details of the statistical analysis plan, including any adjustment for baseline variables, subgroup analyses, interim analyses, or sample-size justification, are not reported in the registry record. The absence of these details in the record should not be read as proof that a procedure was or was not performed; it means the registry information does not establish it.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists zero participants affected by serious adverse events in each of the three groups. The corresponding numbers at risk are 19 in the treatment-naïve ABT-450/r (250/100 mg) group, 14 in the treatment-naïve ABT-450/r (150/100 mg) group, and 17 in the non-responder ABT-450/r (150/100 mg) group. These are group-specific registry counts, not a randomized safety comparison.

The registry also records other adverse events in 17 of 19 participants, 13 of 14 participants, and 13 of 17 participants, respectively. These figures should be kept separate from the serious adverse-event counts: they describe a different category in the adverse-event record. No serious adverse-event terms are listed. Death counts are not reported in the registry record.

As a general statistical point, a zero count in a group is an observed count, not proof that an event is impossible or that the true risk is zero. The record’s group sizes and event counts provide limited descriptive information; they do not establish comparative safety, especially because treatment allocation was non-randomized and the groups were not like-for-like controls. The registry does not report further details about event definitions, severity beyond the serious category, or timing.

13. What the Result Does, and Does Not, Mean

The registry record establishes that this completed, open-label Phase 2 study evaluated ABT-450/r with ABT-333 and ribavirin in treatment-naïve participants and previous non-responders with genotype 1 chronic HCV infection. It also defines the primary endpoint as the percentage with HCV RNA below the lower limit of detection from Week 4 through Week 12, using a threshold of < 15 IU/mL.

That endpoint definition does not show how many participants met the threshold. The primary result, its uncertainty, and the statistical comparison are not reported in the registry record. The listed secondary outcomes likewise do not establish results; their estimates are not reported in the registry record. Thus, the record as described supports interpretation of the study question and methods, but not a conclusion about the magnitude or precision of antiviral activity.

The group structure also limits comparative interpretation. Participants were not randomized, and the registry explicitly warns that the arms are not a like-for-like control comparison. Differences among the treatment-naïve groups or between treatment-naïve participants and previous non-responders cannot be attributed to dose or treatment history alone from this design. The study has no randomized control group described in the record.

The serious adverse-event entries show zero affected participants in each listed group, alongside other adverse-event counts. These are descriptive counts from the registry and should not be treated as proof of absence of risk or as evidence that one regimen is safer than another. Death counts are not reported in the registry record.

As a general principle, evidence about a treatment’s effect depends on the observed outcomes, their uncertainty, and the study design. Here, the registry supplies the endpoint and design context but does not report the primary estimate or inferential results. No medical conclusion about benefit or harm follows from the available information alone.

14. Why This Trial Matters Statistically

This study illustrates why a clearly defined endpoint is only one part of statistical interpretation. The primary measure is specific: the percentage with HCV RNA below the lower limit of detection from Week 4 through Week 12, with the threshold set at < 15 IU/mL. Knowing the time window, measurement threshold, analysis population, and missing-data rule helps readers understand what the planned percentage represents.

It also illustrates the importance of design when interpreting group results. The trial was non-randomized and open-label, with groups distinguished by treatment history and, in treatment-naïve participants, by ABT-450/r dose. Because the registry cautions that the arms are not like-for-like controls, a difference between group percentages would not have the same interpretation as a randomized treatment comparison. A study can still describe outcomes within its enrolled groups, but comparative claims require careful attention to allocation and possible group differences.

The record also shows why estimates need uncertainty information. A percentage alone cannot communicate how precisely an outcome is estimated, and the endpoint result and its interval are not reported in the registry record. The listed outcome definitions cannot substitute for results. Similarly, a missing-data rule is informative, but without the amount and pattern of missingness, readers cannot judge its effect on the estimate.

Finally, the presence of multiple secondary outcomes raises a general question about how results are interpreted across a set of analyses. The registry lists several virologic and other outcomes, but its multiplicity strategy is not reported in the registry record. This distinction between what a record defines and what it reports as an analysis result is central to transparent evidence appraisal.

15. 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 the primary endpoint result. It therefore does not provide the percentage meeting the suppression criterion, the underlying numerator and denominator, or an interval expressing uncertainty. The listed secondary outcomes also lack reported results in the registry information described.

The non-randomized design and absence of masking limit what can be inferred from comparisons across groups. Treatment history differs between treatment-naïve participants and previous non-responders, while the treatment-naïve groups differ in ABT-450/r dose. The registry explicitly states that the arms are not a like-for-like control comparison. Baseline characteristics and details of allocation are not reported in the registry record.

The analysis population and primary missing-data rule are stated, but the number and reasons for missing observations are not reported in the registry record. Sensitivity analyses and missing-data procedures for secondary outcomes are also not reported. These gaps make it difficult to assess whether conclusions would be robust to other plausible assumptions.

The registry lists a range of secondary outcomes, but a multiplicity strategy, statistical analysis plan, sample-size justification, interim analyses, and adjusted analyses are not reported in the registry record. Their absence from the record does not establish whether they were conducted; it limits what can be verified from the recorded information.

For safety, the registry provides serious and other adverse-event counts by group, but no serious adverse-event terms are listed and death counts are not reported in the registry record. The non-randomized design also prevents a strong comparative safety interpretation from these group counts alone. Further detail about event definitions and timing is not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of ABT-450 With Ritonavir (ABT-450/r) When Given Together With ABT-333 and Ribavirin (RBV) in Treatment-Naïve and Non-responder Subjects With Genotype 1 Chronic Hepatitis C Virus (HCV) Infection — NCT01306617.
• Registry record last updated 2015-01-08; status last verified 2014-12.
• Results first posted 2015-01-08.
• 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.

19. Record Summary

This completed Phase 2 study evaluated ABT-450/r with ABT-333 and ribavirin in treatment-naïve participants and previous non-responders with genotype 1 chronic HCV infection. It was open-label, non-randomized, and parallel-group, with enrollment of 50. The registry defines the primary endpoint as the percentage with HCV RNA < 15 IU/mL from Week 4 through Week 12.

The efficacy population included participants who received at least one dose, and missing primary endpoint data were imputed as failures. The primary endpoint result and its uncertainty are not reported in the registry record. The registry lists zero serious adverse events in each group, alongside other adverse-event counts, but the non-randomized groups are not like-for-like controls. Comparative efficacy and safety conclusions are therefore not established by the recorded information.