Drug Utilization of Boceprevir and Clinical Management of Health Outcomes of Interest in Chronic Hepatitis C Participants (P08518): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Drug Utilization of Boceprevir and Clinical Management of Health Outcomes of Interest in Chronic Hepatitis C Participants (P08518) (NCT01544582), a registered phase not stated study. The primary outcome is Baseline Characteristics of Participants Initiating Boceprevir Plus PR Treatment, Telaprevir Plus PR Treatment, or PR Treatment Alone: Weight.

2. Clinical Question

3. Trial Design

This was an observational, prospective follow-up study of boceprevir use and the management of prespecified health outcomes of interest among participants with chronic hepatitis C genotype 1. The official title identifies it as a post-authorization safety study of Victrelis (boceprevir). Its stated purpose was to examine drug utilization and health outcomes under routine clinical care.

The registry lists the study as completed, with a start of 2012-05 and primary completion of 2015-07. Enrollment is listed as 713. The sponsor is Merck Sharp & Dohme LLC. The treatment groups were participants prescribed boceprevir plus PR, telaprevir plus PR, or PR alone. PR refers to peginterferon and ribavirin in the record.

Treatment was not assigned by the study. The record says there was no individual administration of a therapeutic or prophylactic agent assigned in the protocol, and no protocol-required procedures. Physician choice of treatment was based on clinical judgment. Thus, the groups represent treatment received in practice rather than randomized study arms.

This distinction matters for interpretation. People receiving different regimens may differ in ways related to treatment choice, clinical circumstances, or other factors. The registry record does not report a method for adjusting comparisons for such differences. It also cautions that the arms are not a like-for-like control comparison. Any group contrasts should therefore be read as descriptive observations, not as proof that treatment caused a difference.

The registry lists 16 outcome measures and zero analyses. The primary outcome measure is baseline weight; secondary outcomes include anemia, Grade 3/4 neutropenia, Grade 3/4 thrombocytopenia, and serious skin rash. A detailed statistical analysis plan, including any planned comparative modeling, is 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.

Before assignment: Of 713 Chronic Hepatitis C (CHC) participants included in the study, 679 were included in the Analysis Population and 34 were excluded. The Analysis Population comprised participants receiving Boceprevir plus peginterferon and ribavirin (PR), Telaprevir plus PR, or PR alone.

Screening/Eligibility

Reasons for not completing this period:

Analysis Population

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis Population: All CHC genotype-1 participants included in study meeting eligibility criteria and receiving boceprevir plus peginterferon and ribavirin (PR), telaprevir plus PR, or PR alone.

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: Analysis Population: All CHC genotype-1 participants included in study meeting eligibility criteria and receiving boceprevir plus peginterferon and ribavirin (PR), telaprevir plus PR, or PR alone.

6. Primary Endpoint

The registry lists the primary outcome as Baseline Characteristics of Participants Initiating Boceprevir Plus PR Treatment, Telaprevir Plus PR Treatment, or PR Treatment Alone: Weight, measured over Before initiation of CHC treatment (Week 0 baseline).

The primary measure is baseline mean weight in kilograms, summarized with standard deviation. Weight was recorded from the eCRF before chronic hepatitis C treatment, at Week 0 baseline. The population is described as eligible chronic hepatitis C genotype-1 participants receiving one of the three listed treatment regimens and having available demographic data for weight.

As a general statistical matter, a mean gives the central value of a continuous measure, while the standard deviation describes how spread out individual measurements are around that mean. Reporting both can help characterize the participants at treatment initiation. Baseline characteristics are useful for understanding who entered each observed treatment group and for considering whether groups appear comparable on measured features.

Weight is not an efficacy outcome in this record. It does not measure viral response, change during follow-up, or a safety event. Its role is descriptive: it characterizes participants before treatment initiation. The registry record does not include the actual mean weights or standard deviations, nor does it report a comparison test or confidence interval for this endpoint. Consequently, the recorded information does not establish whether baseline weight differed across treatment groups or how precisely any group mean was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean with standard deviation describe?

The primary measure is continuous: weight in kilograms. A mean is the arithmetic average of the recorded values in a group. The standard deviation describes the spread of individual values around that average. A small standard deviation would indicate that values are more concentrated around the mean, while a larger one would indicate greater spread. This is general interpretation, not a statement about the unreported weight results in this study.

A mean and standard deviation describe different features of a distribution. The mean identifies its center in a simple summary, while the standard deviation conveys variability among participants. Neither alone shows the full shape of the distribution or whether a small number of unusual values influence the average. The registry record does not report distributional plots, medians, ranges, or other summaries for weight. It also does not report an inferential comparison of baseline weight by treatment group.

What does baseline timing mean?

Weight was measured before initiation of chronic hepatitis C treatment at Week 0 baseline. A baseline description characterizes participants at treatment initiation; it is not a measure of change attributable to treatment. A comparison of baseline characteristics can help readers understand whether observed groups seem similar on the features reported, but similarity on one characteristic would not establish similarity on unmeasured factors. The actual weight summaries are not reported in the registry record, so even this descriptive comparison cannot be made from the available result details.

How should observational treatment groups be understood?

In a randomized study, an assignment process is used to form treatment groups. Here, the record describes physician choice based on clinical judgment and states that no treatment was assigned by the study. This means treatment groups reflect routine-care decisions. As a general principle, treatment choice can be associated with patient or clinical characteristics, and those characteristics may also be associated with outcomes. A raw difference between groups can therefore reflect factors other than the treatment itself.

The registry record explicitly notes that allocation is not stated and that the arms are not a like-for-like control comparison. It does not report adjustment methods that would address differences between groups. Without such information, a descriptive contrast cannot be interpreted as an unbiased causal effect. Even a statistical adjustment, if one had been reported, would depend on which factors were measured and how they were modeled.

What do the safety counts convey?

The safety summaries identify participants at risk and participants recorded as affected for serious and other adverse events within each group. Counts are useful for seeing the number of recorded cases, while the at-risk count gives context for the group represented. A count alone does not describe event severity, duration, recurrence, or the timing of an event. The registry record does not provide those details in the information described.

The serious-event terms are accompanied by percentages, but term-specific denominators and calculation details are not reported in the registry record. It is therefore important not to infer those details or combine the listed percentages. The event terms may describe different clinical events, and the record does not say whether one participant could contribute to more than one term. Death values are null in the record; this means death counts are not reported in the registry record, not that no deaths occurred.

How do uncertainty and over-dispersion matter in general?

A confidence interval is a statistical summary of uncertainty around an estimate. Its width depends on the amount of information and the variability represented by the data, as well as the analysis method. A narrower interval generally indicates greater precision under the model used; it does not remove bias from nonrandom treatment selection or establish causation. No confidence intervals are reported for the primary measure or safety comparisons.

Over-dispersion is a general issue in count data when observed variability exceeds what a simple statistical model assumes. If present, it can make standard errors from an overly simple model too small and uncertainty appear less than it is. The registry record does not describe a count-data model, report a dispersion assessment, or provide model-based estimates. Over-dispersion therefore cannot be assessed from the reported information and should not be presumed to have been present or absent.

What do the planning assumptions mean?

The registry record describes sample-size planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. For time-to-event tables, the record says the illustration gives the total number of events using the Schoenfeld method; other illustrations give participants per arm.

These are planning illustrations, not observed power and not evidence about the study’s design. The record does not report a sample-size justification from the study protocol, and the illustrations are explicitly described as not being the trial’s own design. A calculation based on an observed effect is sensitive to that effect estimate and should not be treated as proof that the study was adequately powered. The record lists zero analyses, and no inferential result is available to evaluate against the planning assumptions.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Boceprevir + PR", "Telaprevir + PR", "PR Alone")
n   <- c(280, 280, 74)
m   <- c(77.7, 77, 71.7)
sp  <- c(17.4, 15.5, 13.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Boceprevir + PR  280  77.700  17.400  75.653  79.747
CARM  Telaprevir + PR  280  77.000  15.500  75.177  78.823
CARM  PR Alone  74  71.700  13.700  68.526  74.874

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 16 outcome measures, including baseline weight as the primary measure and safety outcomes such as anemia, Grade 3/4 neutropenia, Grade 3/4 thrombocytopenia, and serious skin rash. It lists zero analyses. A multiplicity strategy—such as a hierarchy of tests, adjustment of significance thresholds, or a distinction between confirmatory and exploratory comparisons—is not reported in the registry record. Thus, the record does not show how multiple outcomes or comparisons were handled statistically.

Missing-data information is limited. The primary population is defined as eligible participants in the three treatment groups with available demographic data for weight. The record does not state how many weight values were missing, why any were missing, or whether missingness was handled through exclusion, imputation, or another approach. Those details are not reported in the registry record. The listed at-risk and affected counts do not establish the completeness of follow-up for every outcome.

The analysis population is described as all eligible chronic hepatitis C genotype-1 participants included in the study and receiving one of the listed regimens; for the primary endpoint, available weight data are additionally required. The registry record does not report whether this population definition differed across other endpoints, whether participants changed treatment, or how such situations were handled. No statistical analysis plan, prespecified model, or missing-data sensitivity analysis is reported. These gaps limit assessment of whether the reported summaries represent all eligible participants and how robust conclusions might be to incomplete observations.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: anaemia (4.1%), myocardial ischaemia (1.4%), multi-organ failure (1.4%), bacterial infection (1.4%), muscle abscess (1.4%).

The serious adverse event counts are listed as 58 affected among 298 at risk for Boceprevir + PR, 50 among 307 at risk for Telaprevir + PR, and 8 among 74 at risk for PR Alone. For other adverse events, the corresponding recorded counts are 178 among 298, 173 among 307, and 25 among 74. These figures describe the groups as recorded; they do not establish that a treatment caused an event or that differences between groups are statistically meaningful.

The listed serious terms are Anaemia (4.1%), Myocardial ischaemia (1.4%), Multi-organ failure (1.4%), Bacterial infection (1.4%), Muscle abscess (1.4%), and Septic shock (1.4%). The record does not report the term-specific denominators or clarify whether participants could be counted under more than one term. Death counts are not reported in the registry record. Because treatment was selected through routine clinical judgment and the arms are not a like-for-like control comparison, these data are best read as descriptive safety reporting rather than causal estimates.

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

The registry record establishes that this was a completed prospective observational study of treatment utilization and health outcomes in chronic hepatitis C genotype-1 participants. Its primary measure was baseline weight before treatment initiation. It also records safety outcomes for participants receiving boceprevir plus PR, telaprevir plus PR, or PR alone. The reported safety counts and serious-event terms describe what was recorded in these groups.

The record does not report the mean or standard deviation for baseline weight. It lists safety counts but does not report comparative estimates, confidence intervals, p-values, or adjusted analyses. It therefore does not support a conclusion about the size or precision of a treatment-group difference. The record also cautions that the groups are not a like-for-like control comparison and that treatment was chosen by physicians in routine care.

As a general principle, observational findings can describe patterns of care and recorded events, but treatment groups may differ for reasons related to clinical judgment or other characteristics. Without a reported analysis addressing those differences, observed contrasts should not be interpreted as causal effects. A lack of reported statistical significance is not evidence of no difference, especially when no inferential analyses are listed.

These results do not establish that one regimen is safer, less safe, more effective, or equivalent to another. Nor do the safety counts alone establish the timing, duration, or clinical course of events. The information is most useful as a description of the registry’s stated population, baseline measure, treatment group definitions, and recorded adverse event summaries, with substantial limits on comparative interpretation.

14. Why This Trial Matters Statistically

This study is statistically notable for its observational design and its focus on treatment use in routine clinical care. The treatment groups were based on physician choice rather than study assignment. That design can describe real-world prescribing and recorded outcomes, but it does not create randomized groups. As a result, group differences may reflect clinical selection and other characteristics as well as any treatment-related differences.

The primary endpoint is a baseline characteristic rather than a treatment outcome. Baseline weight can help describe the participants entering each treatment group, but the registry record does not report the weight summaries. This highlights a distinction between a clearly specified measure and a reported result: the endpoint definition alone cannot show the observed values or their precision.

The registry also lists serious and other adverse event counts, along with selected serious-event terms. Such descriptions can be useful for understanding what was captured during observational follow-up, but they do not substitute for a formal comparative safety analysis. The record lists zero analyses and does not provide inferential estimates or an account of adjustment for group differences.

Finally, the record describes planning illustrations based on an observed effect while stating that these are not the study’s own design. This is an important distinction in statistical reporting: an illustration for planning should not be mistaken for observed power or for a protocol-based sample-size rationale. Together, the record underscores the need to interpret endpoint definitions, design, and reported analysis separately.

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 registry record does not report the primary weight means or standard deviations, despite defining the measurement and population. This prevents evaluation of baseline weight distributions across the treatment groups. It also lists zero analyses, so no inferential comparison is available for the primary endpoint or the listed safety outcomes.

Because the study was observational, treatment was chosen by physicians rather than assigned by the protocol. Allocation is not stated, and the record warns that the arms are not a like-for-like control comparison. The registry record does not report adjustment for differences in participant characteristics, treatment selection, or other potential confounders. Causal interpretation is therefore limited.

Important details about measurement and follow-up are not reported in the registry record, including the number of missing weight measurements, the handling of missing data, term-specific safety denominators, and the timing or duration of adverse events. Death counts are also not reported. The record does not state whether adverse-event terms could overlap or how the listed percentages were calculated.

A statistical analysis plan, multiplicity approach, and detailed sample-size justification are not reported in the registry record. The planning illustrations are described as not being the study’s own design and should not be treated as observed power. These limitations make it difficult to assess precision, completeness, robustness, and the strength of any between-group inference.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Drug Utilization of Boceprevir and Clinical Management of Health Outcomes of Interest in Chronic Hepatitis C Participants (P08518) — NCT01544582.
• Registry record last updated 2016-09-16; status last verified 2016-07.
• Results first posted 2016-09-16.
• 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.

19. Record Summary

NCT01544582, titled “Drug Utilization of Boceprevir and Clinical Management of Health Outcomes of Interest in Chronic Hepatitis C Participants (P08518),” is an observational prospective post-authorization safety study of boceprevir in chronic hepatitis C genotype-1 participants. The registry lists enrollment of 713, status completed, a start of 2012-05, and primary completion of 2015-07. The sponsor is Merck Sharp & Dohme LLC.

Participants received boceprevir plus PR, telaprevir plus PR, or PR alone through routine clinical management. The primary measure is mean baseline weight with standard deviation at Week 0. Secondary outcomes include anemia, Grade 3/4 neutropenia, Grade 3/4 thrombocytopenia, and serious skin rash. The record lists 16 outcome measures and zero analyses. Baseline weight summaries and a comparative statistical analysis are not reported in the registry record. The safety counts are descriptive, and the record cautions that treatment groups are not a like-for-like control comparison.