A Study of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir With or Without Sofosbuvir and Ribavirin in Direct-Acting Antiviral Agent Treatment-Experienced Adults With Chronic Hepatitis C Virus Infection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir With or Without Sofosbuvir and Ribavirin in Direct-Acting Antiviral Agent Treatment-Experienced Adults With Chronic Hepatitis C Virus Infection (NCT02356562), a na phase 2 study. The primary outcome is Percentage of Part 1 Participants With Sustained Virologic Response 12 (SVR12) Weeks Posttreatment.

2. Clinical Question

The central statistical question concerns the proportion meeting a prespecified virologic threshold after treatment, rather than a comparison against a concurrent control group. The record’s definition makes the assessment time part of the endpoint: the HCV RNA criterion is evaluated 12 weeks after the last dose of study drug. This is a binary outcome for each participant—meeting or not meeting the stated threshold—and the primary result would ordinarily summarize the proportion meeting it in the defined Part 1 population.

The study also lists outcomes concerning SVR12 in Part 2, on-treatment virologic failure, and post-treatment relapse. Those outcomes address other aspects of virologic response and treatment course, but the registry record does not supply their numerical results. Since the primary endpoint result is not reported, the record cannot establish the observed Part 1 response proportion or its precision. The study’s design and endpoint can be described, but the posted record does not support a numerical estimate of the primary outcome.

3. Trial Design

This is a completed, open-label phase 2 study with a single-group model and no applicable allocation. It enrolled 29 participants and evaluated ombitasvir/paritaprevir/ritonavir and dasabuvir, with or without sofosbuvir and ribavirin, in adults with genotype 1 chronic hepatitis C who had experienced treatment failure after direct-acting antiviral therapy. The study began on 2015-02-03, and primary completion is recorded as 2016-10-28. AbbVie is listed as the sponsor.

The study description divides participants according to prior treatment history. Part 1 concerned people previously treated with ombitasvir/paritaprevir/ritonavir and dasabuvir, with or without ribavirin, who experienced treatment failure. Part 2 concerned people previously treated with sofosbuvir/ledipasvir who experienced treatment failure. The brief summary describes approximate planned enrollment for each part, but the registry’s overall enrollment is 29. The primary endpoint analysis was restricted to Part 1; the record says data from Parts 1 and 2 were not combined for analysis.

The Part 1 treatment is described as 3-DAA given with sofosbuvir, with or without ribavirin, while the broader regimen description allows the listed drugs in combinations with or without sofosbuvir and ribavirin. The Part 2 group is described as 3-DAA with ribavirin. The record also describes treatment duration as 12 or 24 weeks. These are regimen descriptions, not evidence that the groups were assigned by randomization.

Open-label means that masking was not used. Along with the lack of randomized allocation, this limits the role of the study as a controlled comparative design. The parts reflect distinct prior-treatment histories and are not described as equivalent groups receiving alternative randomized interventions. The registry record does not report a statistical analysis plan, a sample-size justification, or a detailed account of how participants were assigned among regimen variations.

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: The intent-to-treat (ITT) population consisted of all enrolled participants who received at least 1 dose of study drug.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All Part 1 participants who received at least 1 dose of study drug (ITT population). Per protocol, data from Parts 1 and 2 were not combined for analysis.

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.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Part 1 Participants With Sustained Virologic Response 12 (SVR12) Weeks Posttreatment, measured over 12 weeks after the last dose of active drug.

The primary endpoint is the percentage of Part 1 participants with sustained virologic response 12 weeks after post-treatment, with the assessment time specified as 12 weeks after the last dose of active drug. SVR12 is defined as plasma hepatitis C virus RNA below the lower limit of quantification at that assessment. The record identifies the analysis population as all Part 1 participants who received at least one dose of study drug, described as the ITT population.

This type of endpoint converts each participant’s laboratory result at a defined follow-up time into a binary classification: the threshold is met or it is not. The percentage summarizes the frequency of participants meeting the criterion in the stated population. The fixed follow-up timing matters because the endpoint is not simply an on-treatment viral measurement; it assesses whether the specified virologic threshold is present after treatment has ended.

In general, a sustained-response endpoint is used to describe a post-treatment virologic outcome at a defined time, rather than immediate change during treatment. It does not, by itself, describe every aspect of safety, tolerability, or longer-term health. Nor does an observed percentage from a single-group study establish what would have happened under another regimen or without treatment.

The registry record lists the endpoint definition and a 95% confidence interval as its dispersion measure, but it does not report the observed percentage or interval. Consequently, the magnitude and statistical precision of the primary endpoint cannot be evaluated from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a percentage endpoint represent?

The primary endpoint is expressed as a percentage of participants meeting the SVR12 definition. In general, a binary endpoint classifies each participant according to whether a stated event or criterion occurred. The proportion meeting the criterion is a descriptive summary of that outcome in the analysis population. Here, the criterion is plasma HCV RNA below the lower limit of quantification at the specified post-treatment assessment.

The percentage is meaningful only when its population and outcome definition are clear. The record identifies the primary population as Part 1 participants who received at least one dose of study drug, and it specifies the assessment time relative to the last dose. Those details set the scope of the endpoint. They do not supply the observed count or percentage, which are not reported in the registry record.

How should a confidence interval be understood?

The endpoint lists a 95% confidence interval as its measure of dispersion. In general, a confidence interval gives a range of values compatible with the observed data under a stated statistical method and its assumptions. It conveys uncertainty in the estimated proportion, rather than measuring the spread of individual participant outcomes. The actual interval is not reported in the registry record, so its width and the precision of the estimate cannot be assessed.

A confidence interval is also not a guarantee that a particular interval contains the true value. Its interpretation depends on the method used and on assumptions about the data. The registry record does not report the calculation method for the interval, so further details about its construction are not available.

Why does the design affect interpretation?

The record describes an open-label study, no applicable allocation, and a single-group model. These features mean the study is not presented as a randomized comparison. In general, a randomized concurrent control can help distinguish treatment effects from differences in patient characteristics, time, and other influences. Without that comparison, an observed outcome proportion describes participants in the study but does not by itself establish what would have happened under an alternative strategy.

The study is organized into two parts based on prior treatment histories. The primary analysis population belongs to Part 1, and the record explicitly says that data from the parts were not combined. The distinct histories matter: comparisons between the parts would not automatically isolate a treatment effect, because the populations differ by their prior treatment experience and the regimen descriptions also differ. The record does not describe a planned direct comparison between the parts.

What does the planning illustration mean?

The registry record includes sample-size planning assumptions based on the observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. The planning illustration considers detecting a stated fraction of the observed effect. This is a hypothetical design calculation, not a result from the trial and not observed power. The record’s own trial design is described as single group, so the illustration’s equal-allocation, two-arm assumptions should not be mistaken for the study’s actual allocation.

In general, a planning calculation estimates how much information a future design might need under selected assumptions. Such a calculation depends on the effect used, the chosen statistical test, the allocation, and the desired operating characteristics. The registry record does not report the sample-size justification for the original trial. Nor does the available information support recreating or independently checking the planning illustration’s numerical values. These assumptions should therefore be read as planning context, not as evidence that the trial had a particular probability of detecting an effect.

Why can variability affect analysis?

For binary outcomes, the amount of uncertainty depends in part on how many observations contribute and how the outcomes are distributed. More generally, over-dispersion occurs when the variability in data exceeds what a statistical model assumes. If a model fails to account for over-dispersion, its uncertainty estimates can be too small, making results appear more precise than warranted. The registry record does not state that over-dispersion was present or identify a model that assessed it; this is a general statistical consideration, not a finding about this study.

What analysis details are unavailable?

The registry record names the primary outcome, analysis population, endpoint timing, and confidence-interval measure. It does not report the observed primary result, the interval, the method for calculating that interval, or a detailed statistical analysis plan. It also does not report whether there were interim analyses, what procedures were used for missing measurements, or how any multiplicity concerns were handled. These elements should not be inferred from the phase, open-label status, or endpoint definition.

The record’s primary population includes Part 1 participants who received at least one dose, but that wording alone does not establish how participants with missing follow-up measurements were classified. In general, missing-data handling can affect a binary endpoint because participants without an assessment may not be classifiable as meeting or not meeting the criterion. Without the registry’s method or participant-level disposition information, the effect of missingness cannot be evaluated.

Finally, the record lists secondary outcomes but does not report their numerical analyses. A defined list of outcomes is not the same as a reported statistical result. Interpretation should remain tied to outcomes for which estimates and methods are actually available; in this case, the registry record does not provide the primary numerical estimate needed for that assessment.

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("Part 1, 3-DAA With SOF With or Without RBV")
n      <- c(22)
events <- c(21)
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  Part 1, 3-DAA With SOF With or Without RBV  22  21  95.5  77.2  99.9  78.2  99.2  78.1  98.9

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary endpoint and secondary outcomes concerning Part 2 SVR12, on-treatment virologic failure, and post-treatment relapse. It does not report whether formal multiplicity procedures were used, whether testing was hierarchical, or whether secondary outcomes were treated as descriptive. A multiplicity adjustment or testing sequence is not reported in the registry record. Without that information, the interpretation of any collection of inferential tests cannot be assessed; numerical analysis results are not reported in any case.

The primary analysis population is described as all Part 1 participants who received at least one dose of study drug, identified as the ITT population. The record says the data from Parts 1 and 2 were not combined for analysis. This clarifies the intended scope of the primary endpoint, but the record does not state the number of Part 1 participants included in that analysis or provide a participant flow describing exclusions or missing assessments.

Missing-data handling is not reported in the registry record. In general, a missing post-treatment measurement can prevent classification against a binary endpoint definition. Methods may make different assumptions about such participants, and those choices can affect an estimated percentage. No assumption or method should be attributed to this study without a report of the analysis approach.

The registry record also does not report an interim-analysis plan, imputation method, sensitivity analysis, or detailed statistical analysis plan. Those details cannot be inferred from the endpoint definition or the study’s completed status. The posted information supports identification of the stated population and outcomes, but leaves important aspects of analysis and missingness unresolved.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cellulitis (4.5%), pneumonia (4.5%).

The registry record reports serious adverse events for two groups. In Part 1, 2 participants were affected among 22 at risk; in Part 2, 0 were affected among 7 at risk. These figures describe the recorded serious-event counts in the listed groups. They are not comparative estimates from randomized treatment arms, and the groups should not be treated as like-for-like controls.

Cellulitis and pneumonia are each listed among the top serious event terms at 4.5%. These percentages describe terms in the safety record; the registry information does not establish whether the same participant could contribute to more than one term. The record also lists other adverse events affecting 20 of 22 at risk in Part 1 and 6 of 7 at risk in Part 2. The categories are distinct registry fields, and their counts should not be combined.

Death counts are not reported in the registry record. The available figures do not provide event timing, duration of follow-up, severity details beyond the serious-event designation, or a full accounting of exposure by regimen variation. Because the study is open-label and lacks randomized allocation, differences between these group counts cannot establish that a regimen caused a difference in risk. They should be read as descriptive safety reporting, with the stated group denominators and the limitations of the record in mind.

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

The registry record describes a phase 2 study of antiviral regimens in adults with genotype 1 chronic hepatitis C and prior direct-acting antiviral treatment failure. It defines the primary outcome as SVR12 in Part 1 and identifies the population intended for that endpoint. This establishes what the study set out to measure, but the numerical primary result is not reported in the registry record.

Accordingly, the posted information does not establish the observed Part 1 response proportion or how precisely it was estimated. The record also does not report a numerical primary confidence interval. Without those results, the endpoint cannot be summarized as a particular level of response, and there is no basis in the posted data for judging the precision of such an estimate.

The study’s structure also limits comparative interpretation. It is described as open-label, single-group, and without applicable allocation. Part 1 and Part 2 reflect different prior treatment histories, and the registry says their data were not combined for analysis. Any outcome proportion within a part would be descriptive of that part’s participants and study conditions; it would not, by itself, show what would have occurred under another regimen.

The safety counts provide a separate description of recorded serious and other adverse events in the listed groups. They do not fill the efficacy reporting gap and should not be interpreted as randomized comparisons. The registry does not report deaths, and the available event information does not include all details needed to compare exposure or follow-up across regimen variations.

In general, a trial record can clarify the population, treatment structure, and outcome definitions even when numerical results are unavailable. It cannot support conclusions about treatment effects, comparative benefits, or the balance of outcomes when the relevant estimates and analysis details are absent. The registry record is therefore informative about the study question and design, but incomplete for interpreting its primary endpoint result.

14. Why This Trial Matters Statistically

This study illustrates why a clearly stated endpoint is not enough for statistical interpretation. The registry record defines SVR12, specifies the post-treatment assessment time, and identifies the Part 1 population. Those details are essential for understanding what a reported percentage would represent. Yet without the numerical estimate and confidence interval, the endpoint’s observed frequency and precision remain unknown.

The design also demonstrates the distinction between describing an outcome and estimating a comparative effect. A single-group, open-label study can describe what was observed among participants receiving the studied regimens. It does not provide the randomized control contrast needed to interpret differences causally. The separate parts are defined by treatment history, so their outcomes cannot be treated as if they arose from interchangeable groups assigned to alternatives.

The record further shows the importance of keeping planning calculations separate from observed results. A planning illustration based on stated assumptions is not the same as a trial outcome and does not establish observed power. Its assumptions include a two-arm equal-allocation setup, whereas the trial model is described as single group. Recognizing that difference prevents a planning aid from being mistaken for the design or results of the completed study.

Finally, the record highlights the role of analysis transparency. Information about missing outcome measurements, multiplicity, interval construction, and the analysis plan is not reported. These details influence how an endpoint estimate should be understood. When they are unavailable alongside the outcome estimate itself, readers can describe the research question and design but cannot fully evaluate the statistical evidence for the primary endpoint.

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 principal limitation for interpreting efficacy is that the registry record does not report the primary SVR12 percentage or its 95% confidence interval. Although the endpoint definition and Part 1 analysis population are stated, the result’s magnitude and precision cannot be assessed. Numerical results for the listed secondary outcomes are also not reported.

The study is open-label and has no applicable allocation, with a single-group model. It therefore does not provide a randomized control comparison. The two parts are distinguished by prior treatment history and were not combined for analysis; comparing them would not isolate a treatment effect. The registry does not describe the assignment process for the regimen variations in enough detail to support a more specific comparison.

The record does not report how missing post-treatment measurements were handled, how many participants contributed to the primary analysis, or whether sensitivity analyses were conducted. It also does not report a detailed statistical analysis plan, multiplicity procedures, interim analyses, or the method used to calculate the confidence interval. These omissions limit appraisal of the analysis even apart from the absent numerical outcome.

Safety information is descriptive and does not include death counts. The registry does not provide all details needed to assess event timing, duration of follow-up, or exposure across regimen variations. The serious-event terms and group counts should therefore be interpreted within the limited information recorded, not as estimates from a controlled safety comparison.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir With or Without Sofosbuvir and Ribavirin in Direct-Acting Antiviral Agent Treatment-Experienced Adults With Chronic Hepatitis C Virus Infection — NCT02356562.
• Registry record last updated 2017-12-20; status last verified 2017-10.
• Results first posted 2017-11-24.
• 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

NCT02356562 is a completed, open-label phase 2 study sponsored by AbbVie. It enrolled 29 participants with genotype 1 chronic hepatitis C and prior direct-acting antiviral treatment failure. The study evaluated ombitasvir/paritaprevir/ritonavir and dasabuvir, with or without sofosbuvir and ribavirin, and was organized into parts defined by prior treatment history.

The primary endpoint was the percentage of Part 1 participants with SVR12, assessed 12 weeks after the last dose of active drug. The analysis population was Part 1 participants who received at least one dose, and data from the two parts were not combined for analysis. The record does not report the primary endpoint percentage or confidence interval. Serious adverse event counts are reported for the listed groups, while death counts are not reported in the registry record.