Increasing Cure Rate of Hepatitis C Therapy in Obese Hepatitis C Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Increasing Cure Rate of Hepatitis C Therapy in Obese Hepatitis C Patients (NCT00871845), a non-randomized na study. The primary outcome is Percentage of Participants With HCV RNA (Early Virological Response).

2. Clinical Question

The question therefore combines a comparison of groups with different body-size categories and interest in a weight-management approach. Those are not equivalent questions: a difference between the lean and overweight groups would not, by itself, isolate the effect of the educational intervention or weight loss. Since allocation was non-randomized and the record does not report an outcome analysis, the posted information cannot establish whether the groups differed in early virological response or why they might have differed.

3. Trial Design

The registry describes a parallel, non-randomized study with no masking. Enrollment is recorded as 36, and the status is terminated. The phase is recorded as NA. The study start is listed as 2008-09 and primary completion as 2011-08. The registry record does not state why the study was terminated.

The two arm descriptions identify a lean, non-obese, treatment-naive group and an overweight, treatment-naive group. The lean group is described as having BMI <25. The overweight group is described as having BMI ≥ 25 and receiving dietary and lifestyle education. Its description includes a one-time 15 minute weight-loss instruction and pamphlet and a weight-management program with 5 weekly one-hour nutrition and physical-exercise education sessions; the description is cut off after that point. The lean arm's description does not list this educational program.

Non-random allocation is important when interpreting any comparison. Groups formed according to body-size category may differ in other characteristics, and the registry does not report an adjustment strategy that would address such differences. The record also does not explain how participants entered each group or whether other aspects of hepatitis C treatment were standardized.

The study summary mentions Orlistat as part of the question about weight loss, but the registered intervention listing names only dietary and lifestyle modification educational sessions. The record does not give enough detail to resolve the role of Orlistat in the study. Neither a protocol description nor a rationale for the enrollment target is reported in the registry record. No results analysis is listed.

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: While the initial study design included a drug intervention, drug intervention was not done. The study team could not identify an adequate study population willing to undergo drug intervention and funding to cover the costs of the drug intervention. Therefore, the only intervention was weight loss instruction/management.

Overall Study

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 Participants With HCV RNA (Early Virological Response), measured over Week 12.

The primary endpoint is the percentage of participants with HCV RNA meeting the registry's definition of early virological response at Week 12. That definition is a greater than 2-log10 decline in serum HCV RNA from the pretreatment baseline or an undetectable serum HCV RNA at treatment week 12. The endpoint is binary at the participant level: each participant either meets the stated response definition or does not.

In general, an early virological response is a treatment-response measure based on change in the virus level during therapy. Defining the endpoint in advance gives a consistent rule for classifying participants and makes it possible to report the proportion meeting that rule. The percentage can describe the frequency of response within a group, while a comparison between groups would require an analysis that accounts for the study design and relevant uncertainty.

The registry names this as the primary outcome and gives Week 12 as its timeframe, but does not report the number or percentage of participants meeting the definition in either group. It also does not report an estimated group contrast or a confidence interval. Consequently, the endpoint's intended meaning can be described, but its observed result cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a binary percentage outcome: whether participants met the early virological response definition. For an outcome of this kind, a basic descriptive summary is the number of participants meeting the definition and the percentage within each group. A comparison may then estimate how the groups differ, but the choice of comparison and the way uncertainty is calculated should reflect the design and available data. The registry record does not report counts, percentages, a group contrast, or the method used to analyze the primary endpoint.

What does a confidence interval communicate?

In general, a confidence interval expresses the uncertainty around an estimated quantity under the assumptions of the analysis. It is not a guarantee that the true value lies within the particular interval, and it does not repair design limitations such as confounding. For this trial, no confidence interval for early virological response is reported in the registry record. Thus, the precision of any endpoint estimate cannot be evaluated from the posted results.

What can a p-value establish?

In general, a p-value describes how unusual data at least as inconsistent with a specified null model would be if that model and the analysis assumptions were correct. It does not measure the size or clinical importance of an effect, nor does it show the probability that a hypothesis is true. No primary-outcome p-value or analysis is reported in the registry record, so statistical evidence for a group difference cannot be assessed.

Why does the allocation method matter?

Randomization, when used and implemented appropriately, helps make comparison groups similar on average with respect to both measured and unmeasured characteristics. This study is explicitly listed as non-randomized. The registry also says the arms are not a like-for-like control comparison. As a general matter, a comparison of non-randomized groups can be affected by confounding: characteristics associated with group membership may also be related to the outcome. Statistical adjustment can address some measured differences under suitable assumptions, but it cannot automatically remove unmeasured differences. The registry record does not report an adjustment plan or adjusted analysis.

The parallel structure means the record describes separate groups rather than a stated within-participant comparison. The record does not give further detail about the timing or conduct of assessments beyond the primary endpoint timeframe, Week 12. It does not report the statistical model, handling of baseline measurements, or a prespecified analysis population.

How should the planning assumptions be read?

The sample-size assumptions describe a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustration is framed as detecting a stated fraction of the observed effect. These are planning assumptions, not a report of the trial's original design justification and not observed power. The registry record does not report the trial's own sample-size justification, nor does it supply the effect values or resulting planning counts in the information available for this analysis. Any such illustrations should be understood as hypothetical planning scenarios, not as additional trial findings.

In general, power is a property of a planned design under specified assumptions; it is not a measure of how persuasive an observed result is. Post hoc calculations based on an observed effect do not substitute for reporting an estimate and its uncertainty. Since the primary outcome result is not reported, there is no basis for judging the precision of the endpoint or for interpreting a planning illustration as evidence that the trial could or could not detect a particular difference.

What would over-dispersion mean?

In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. It can make standard errors too small and confidence intervals too narrow if the model does not account for that extra variability. This concept is relevant when a chosen model has a variance assumption that may not fit the data. The registry does not report a model for the primary outcome, diagnostics, or evidence of over-dispersion, so there is no trial-specific claim to make about it.

More broadly, the registry record does not report interim analyses, multiplicity procedures, missing-data methods, or a detailed statistical analysis plan. Those omissions do not establish that such procedures were absent from the conduct of the study; they mean they are not reported in the registry record. Without endpoint results and analysis details, the statistical strength, precision, and robustness of a treatment-response comparison remain unknown.

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("Lean", "Overweight")
n      <- c(11, 25)
events <- c(9, 13)
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  Lean  11  9  81.8  48.2  97.7  52.3  94.9  51.6  94.5
ARM  Overweight  25  13  52.0  31.3  72.2  33.5  70.0  33.4  70.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures, but the information available for the primary endpoint names only the early virological response measure and does not give results for it. The number of analyses listed is 0. How the outcome measures were organized into primary, secondary, or exploratory analyses beyond the identified primary endpoint is not reported in the registry record.

Multiplicity arises when several outcomes, comparisons, or analyses are examined. In general, the more opportunities there are to identify a statistically unusual result, the more important it is to understand which analyses were planned and how the analysis plan addressed that issue. The registry record does not report multiplicity adjustment, a hierarchy of tests, or an interim-analysis plan. It is not possible to determine from the record whether such procedures were used.

Missing-data handling is also not reported in the registry record. There is no statement describing whether participants without a Week 12 measurement were excluded, classified in another way, or handled using a statistical method. The analysis population is not reported, and the record does not specify whether all enrolled participants were included in the primary analysis.

These gaps matter because the interpretation of a percentage depends on who was counted and how unavailable outcome measurements were treated. They also affect the interpretation of uncertainty and any comparison between groups. The registry enrollment is 36, but that value alone does not establish how many participants contributed to the primary endpoint. The safety denominators should not be assumed to be the primary-outcome analysis populations.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The serious adverse event figures record 0 events among 11 participants at risk in the lean group and 0 among 25 participants at risk in the overweight group. The record also lists 0 other adverse events for each group, with 11 and 25 participants at risk, respectively, and 0 deaths in each group. These are the safety counts reported for the listed groups.

A count of zero means no event of the corresponding type was recorded among the participants represented by that safety denominator. It does not establish that the risk of an event is zero, and it does not show that the groups had identical safety experience in every respect. With no events recorded, the registry figures do not provide a basis for a comparative risk estimate or for judging the range of plausible event rates. The record does not describe how adverse events were collected, the observation period for these safety counts, or whether any participants were excluded from the safety population.

These safety counts should be kept separate from the primary efficacy endpoint. They do not indicate whether participants met the early virological response definition, and they do not establish a benefit or harm attributable to the educational intervention or any other aspect of care.

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

The registry record establishes that this was a non-randomized, parallel study involving lean and overweight participants naive to hepatitis C therapy, with dietary and lifestyle education described for the overweight group. It specifies a Week 12 early virological response endpoint and defines the response criterion. It also posts safety counts for serious adverse events, other adverse events, and deaths.

However, the primary endpoint results are not reported in the registry record. No group-specific response percentages, effect estimate, confidence interval, or p-value is available. The posted information therefore does not show whether response differed between the groups or how precisely any such difference was estimated. It also does not establish whether a weight-management approach changed response, or what role Orlistat may have played.

The design further limits what a group comparison could establish. Because allocation was non-randomized and the groups were not described as like-for-like controls, any observed difference could not automatically be attributed to the intervention. A causal interpretation would depend on study conduct and analysis details that are not reported in the registry record.

The absence of a posted primary outcome result is not evidence that there was no difference, just as it is not evidence that a difference existed. Likewise, the zero recorded adverse-event counts do not establish an absence of risk. The appropriate conclusion is limited: the registry defines the study question and reports some design and safety information, while the primary response result and the analysis needed to interpret it are unavailable.

14. Why This Trial Matters Statistically

This study illustrates why a clearly defined outcome is only one part of statistical interpretation. The registry gives a specific early virological response rule and a Week 12 timeframe, which identify what the investigators intended to measure. Without the observed counts and an analysis, however, readers cannot assess the outcome's magnitude, precision, or relationship to the study question.

The design also demonstrates the distinction between comparing groups and estimating an intervention effect. The lean and overweight groups differ by the body-size categories used in the arm descriptions, and the registry classifies allocation as non-randomized. A difference between these groups, if reported, would not automatically represent the effect of dietary and lifestyle education. The record itself cautions that the arms are not a like-for-like control comparison.

In general, statistical interpretation depends on both the numerical results and the assumptions linking those results to the question. Outcome definitions, allocation methods, missing-data handling, analysis populations, and adjustment for potential confounding all shape what a comparison can mean. Several of those analysis details are not reported in the registry record, and no primary endpoint analysis is listed.

The study is therefore useful as an example of how registry descriptions can clarify a research question while leaving important results and methods unavailable. Its posted safety counts can be described, but they do not answer the efficacy question. A careful reading separates what is documented—the design, endpoint definition, and safety counts—from what cannot be concluded: the response rate, a group contrast, and a causal effect of the intervention.

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 most direct limitation is that the registry record does not report the primary endpoint results. It therefore provides no response counts or percentages, no estimated contrast, and no measure of uncertainty. Although enrollment is recorded as 36, the number contributing to the Week 12 endpoint is not reported in the registry record.

The design is non-randomized, and the registry cautions that the arms are not a like-for-like control comparison. The record does not explain how participants were assigned to groups or report an adjustment strategy for potential differences between them. This restricts the interpretation of any group comparison, even if outcome results were available.

The intervention description is incomplete: the overweight arm text ends mid-sentence. The study summary refers to Orlistat, while the intervention listing names dietary and lifestyle educational sessions. The registry record does not clarify the role of Orlistat or provide a complete account of the intervention. It also does not report why the study was terminated.

Analysis details are limited. The statistical model, analysis population, missing-data approach, multiplicity procedures, interim analyses, and trial-specific sample-size justification are not reported in the registry record. The safety figures are available, but the collection methods and observation period for those counts are not described. These limitations mean that the posted information supports a description of the intended endpoint and recorded safety events, but not a statistical assessment of the primary clinical question.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Increasing Cure Rate of Hepatitis C Therapy in Obese Hepatitis C Patients — NCT00871845.
• Registry record last updated 2018-11-05; status last verified 2018-03.
• Results first posted 2018-11-05.
• 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

The registry record describes NCT00871845, titled “Increasing Cure Rate of Hepatitis C Therapy in Obese Hepatitis C Patients.” It is a parallel, non-randomized study with no masking, a recorded enrollment of 36, and terminated status. The listed study period begins in 2008-09, with primary completion in 2011-08.

The study concerns lean and overweight participants naive to hepatitis C therapy. Its primary endpoint is the percentage meeting the early virological response definition at Week 12. The listed intervention is dietary and lifestyle modification educational sessions; the brief summary also mentions Orlistat. The registry record does not report primary endpoint results or a statistical analysis. It records 0 serious adverse events in each group, among 11 participants at risk in the lean group and 25 in the overweight group, and lists 0 other adverse events and 0 deaths in each group.