A Study to Evaluate Preemptive Therapy in Hepatitis C (HCV) Organ Transplant Recipients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Evaluate Preemptive Therapy in Hepatitis C (HCV) Organ Transplant Recipients (NCT04508907), a na phase 4 study. The primary outcome is Rate of Prevention of HCV Viremia in Recipients of HCV Viremic Solid Organs.

2. Clinical Question

3. Trial Design

This is a Phase 4, single-group pilot study with enrollment of 227. The registry lists Mayo Clinic as the sponsor and gives the study status as completed. The study start is recorded as 2020-09-10 and primary completion as 2025-11-01. Those registry entries describe the study record; they do not supply a comparison group or an estimate of treatment effect.

All recipients in the described arm receive combination therapy after receiving an organ from an HCV-viremic donor. Allocation is listed as NA, masking as none, and the study model as single group. There is no like-for-like control arm in this design. In particular, the outcome cannot be compared within this study against a concurrently randomized group receiving a different strategy.

The term pilot identifies the study as a pilot in its official title, but a detailed rationale for the design, a protocol-defined sample-size justification, and any planned interim analyses are not reported in the registry record. The enrollment figure is a reported study characteristic, not evidence by itself that the study was sized to estimate the endpoint with a particular precision.

The record lists two outcome measures and zero statistical analyses. The primary outcome is prevention of HCV viremia at 3 months. Although the study is marked completed, an observed primary outcome value and inferential analysis are not reported in the registry record. Completion status should not be taken to mean that every result is present in the 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

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 Rate of Prevention of HCV Viremia in Recipients of HCV Viremic Solid Organs, measured over 3 months.

The primary endpoint is the percentage of patients who did not become HCV viremic using the preemptive treatment protocol, with a timeframe of 3 months. It is a binary outcome at the participant level: each recipient either becomes viremic or does not become viremic within the specified assessment period. The endpoint is expressed as a percentage of participants.

This outcome is used to describe prevention of the infection state of interest in recipients who receive organs from HCV-viremic donors. In a single-group study, the percentage can describe the observed outcome among enrolled participants, but it does not by itself estimate a contrast against an untreated or alternative-treatment group. Such a contrast would require a suitable comparator and an analysis of differences between groups.

The registry record gives the endpoint definition and timeframe but not the observed percentage, numerator, analysis denominator, or confidence interval. It is therefore not possible to describe the magnitude or precision of the endpoint result from the registry record. The record also does not report how incomplete endpoint assessments, if any, were handled.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods determine how an endpoint is converted into an estimate, how uncertainty is represented, and whether a comparison is made. For this study, the registry record defines a binary primary endpoint but lists zero analyses. A detailed statistical analysis plan, including the estimator and inferential procedure used for the primary endpoint, is not reported in the registry record.

How would a binary endpoint be summarized?

In general, a binary outcome is summarized by counting participants in each outcome category and dividing the count in the category of interest by the number of participants assessed. For this endpoint, the category of interest is not becoming HCV viremic within the stated 3-month timeframe. The resulting proportion may be expressed as a percentage. This description explains the general calculation; it is not a recalculation of the study result, because the registry record does not report the required outcome counts or analysis denominator.

The denominator is important. The number enrolled, the number with an endpoint assessment, and the number included in an analysis can differ when outcome data are missing or participants do not complete follow-up. The record reports enrollment of 227, but does not report the primary endpoint denominator or the way missing assessments were treated. It would be inappropriate to assume that every enrolled participant contributed a complete endpoint observation.

What does a confidence interval add?

In general, a confidence interval describes the statistical uncertainty around an estimate under the assumptions of the method used. For a proportion, its width is influenced by the number of participants with usable outcome data and by the observed distribution across outcome categories. A narrower interval indicates greater precision under that method; a wider interval indicates more uncertainty. A confidence interval does not repair limitations in the study design, establish causality, or guarantee that the interval contains the true value.

No confidence interval for the primary endpoint is reported in the registry record. Nor does the record identify whether an interval was planned or which method would be used. The observed endpoint percentage and its precision therefore cannot be interpreted from the registry information.

What can a single-group design estimate?

In general, a single-group study can describe the outcome observed among participants who receive the study strategy. It does not provide a randomized between-group contrast. A comparison with an external or historical group would require data and assumptions beyond the single-group observation, including whether the groups are sufficiently comparable. No such comparison is reported for this study.

Because there is no separate comparator arm, standard methods for estimating a randomized treatment contrast do not apply to the listed design as if it were a two-arm trial. The record does not report an adjusted comparison, a model for covariates, or another analysis intended to address differences in risk among participants.

How should the planning assumptions be read?

The record describes a planning illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. These are assumptions for a planning illustration, not a description of the enrolled single-group study. The registry record does not report a protocol-based sample-size justification, the observed effect on which the illustration depends, or a numerical planning estimate in the information available for this analysis. Such planning estimates are hypothetical design aids, not observed power and not evidence that the completed study had a particular probability of detecting an effect.

In general, sample-size planning depends on the target effect, variability or event probability, significance level, desired power, allocation, and analysis method. Altering the assumed effect changes the size of study that a planning calculation would suggest. A planning illustration cannot establish that a study was adequately powered after the fact, and it does not substitute for a reported estimate with an uncertainty interval.

Why can event proportions be difficult to model?

General methods for binary outcomes may rely on approximations that work better when expected counts are not sparse. When outcomes are uncommon or very common, some approximate procedures may perform poorly, and exact or alternative interval methods may be considered. The registry record does not report the outcome counts, so the appropriateness of any particular method cannot be assessed. The record also does not state which method, if any, was used.

Over-dispersion is a general concern when variation is greater than a model assumes, for example when outcomes cluster by a feature that a simple model does not represent. A model that ignores extra variation can understate uncertainty. The registry record does not describe a model or report an assessment of over-dispersion, so there is no basis to say that this issue arose or how it was handled in the study.

These statistical concepts explain what would be needed to interpret a binary endpoint estimate. They should not be mistaken for methods documented as having been used. For this study, the registry record states the endpoint and its timeframe but does not report its numerical result, an uncertainty interval, the analysis population, or the statistical procedure.

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("Arm 1: Pre-emptive Treatment Arm")
n      <- c(227)
events <- c(226)
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  Arm 1: Pre-emptive Treatment Arm  227  226  99.6  97.6  100.0  97.5  99.9  97.6  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures, but a multiplicity strategy is not reported in the registry record. Multiplicity concerns arise when several outcomes, timepoints, subgroups, or statistical tests are assessed, because the chance of at least one apparently notable result can increase as more tests are considered. General approaches include designating a primary endpoint in advance or adjusting inference across selected tests. The record identifies a primary endpoint, but does not describe whether or how inference across the listed outcomes was managed.

Zero statistical analyses are listed. This means the registry record does not provide analysis results or document which tests were performed. It should not be read as proof that no analyses were conducted outside the posted record. Details such as an analysis plan, hypothesis tests, confidence intervals, covariate adjustment, and handling of repeated assessments are not reported in the registry record.

Missing-data handling and analysis populations are also not reported in the registry record. The enrollment of 227 does not establish how many participants had a complete primary endpoint assessment at 3 months, whether any participants were excluded from an endpoint analysis, or how missing measurements were treated. The adverse-event fields list 227 at risk for each recorded category, but that does not define the primary endpoint analysis population.

In general, missing outcome data can affect both the denominator and the interpretation of an estimated proportion. Excluding participants with missing assessments, assigning them to an outcome category, or using a model-based approach can lead to different estimates and requires explicit justification. Because the record does not describe a method, no particular missing-data assumption can be attributed to this study.

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 fields list 227 participants at risk and 0 affected in the pre-emptive treatment arm. The other adverse-event fields also list 227 at risk and 0 affected. The record separately reports 8 deaths. No top serious adverse-event terms are listed.

These entries should be read as the safety counts recorded for the arm, not as a complete account of clinical events or their causes. The registry record does not report the deaths’ timing, causes, relationship to treatment, or whether any occurred during the endpoint follow-up period. It also does not state the observation window used for these safety fields or provide event-level narratives.

Zero affected in the listed adverse-event categories does not mean there were no deaths, since deaths are reported separately. Conversely, the death count alone does not establish that deaths were caused by treatment or were unrelated to it. The record does not provide the information needed to make either attribution. These safety entries should not be substituted for the missing primary endpoint result.

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

The record establishes that the study was designed to evaluate preemptive treatment in HCV-seronegative recipients of organs from HCV-viremic donors. It specifies a single treatment arm and a primary endpoint: the percentage of participants who did not become HCV viremic at 3 months. It also reports enrollment of 227 and marks the study completed.

The record does not report the observed value of the primary endpoint, the number of participants who did or did not become viremic, or a measure of statistical uncertainty. Thus, it does not show how often the intended outcome occurred among participants, and it cannot establish the precision of an estimate. A stated endpoint is not itself evidence of the endpoint’s result.

Even if a single-group outcome proportion were available, that value would describe the participants in the treatment arm. Without a comparator, it would not directly quantify the difference between preemptive treatment and another strategy. The design does not include random allocation to a control group, and no such comparison is reported. Findings from other populations or studies cannot be treated as if they were a control arm in this registry record.

The registry record also does not report enough detail to assess the primary analysis population, missing endpoint data, or statistical methods. The listed safety counts provide separate information but do not fill those gaps. The reported 8 deaths have no stated cause or treatment attribution in the record.

The most defensible conclusion is therefore descriptive: the registry specifies what the study intended to measure and reports basic design and safety information, but the posted results do not include a primary endpoint estimate or analysis. The available record does not support a conclusion about the magnitude or precision of the prevention outcome.

14. Why This Trial Matters Statistically

This study addresses a setting in which recipients are HCV-seronegative and the donated organs are from HCV-viremic donors. Statistically, its central feature is the attempt to summarize a binary prevention outcome after a defined follow-up period. Clearly defining the population, outcome, and timeframe is necessary for an interpretable estimate, and the registry does identify those elements for the primary endpoint.

The single-group design also illustrates an important distinction between measuring an outcome and estimating a treatment effect. An outcome proportion can describe what happened among participants who received the intervention. A treatment effect is a contrast: it asks how outcomes differ under alternative strategies. Without a comparison arm, the study record does not provide that contrast. This limits causal interpretation even if a proportion is reported elsewhere.

Reporting the estimate and its uncertainty is as important as defining the endpoint. A percentage without its denominator can be difficult to interpret, and an estimate without an uncertainty measure does not show its precision. In this record, the endpoint value and analysis are not reported, making it impossible to evaluate either the observed outcome or its statistical uncertainty.

The record also highlights why planning assumptions should be kept separate from study results. A hypothetical two-arm calculation does not change the design of a completed single-group study and cannot stand in for an observed endpoint estimate. Likewise, enrollment alone does not establish that an estimate would be sufficiently precise.

These points matter for clinical trial interpretation more broadly: design determines what comparisons are possible, analysis and missing-data choices determine how estimates are formed, and complete result reporting is needed to assess what the data show. Here, the registry record documents the intended question but leaves the primary statistical result unavailable.

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 for interpreting this record is that the primary endpoint result is not reported in the registry record. The outcome definition and 3-month timeframe are available, but the observed percentage, numerator, denominator, and uncertainty measure are not. This prevents assessment of the primary outcome’s magnitude and precision.

The single-group design has no concurrent comparator, and allocation is recorded as NA. Masking is listed as none. These design features mean that the record cannot provide a randomized treatment contrast, and it does not document a comparison capable of separating treatment-related outcomes from other explanations.

Several details needed to assess the endpoint are not reported in the registry record, including the primary analysis population, missing-data methods, statistical analysis plan, and any adjustment for relevant participant characteristics. The numbers of participants receiving each organ type are also not reported. The registry lists kidney, heart, lung and/or pancreas in the study description, but does not give organ-specific outcome estimates.

The safety fields report zero affected in the serious and other adverse-event categories and 8 deaths, but the record does not give the deaths’ causes, timing, or relationship to treatment. The follow-up window for those safety counts is not reported in the registry record. These omissions limit interpretation of the safety entries and prevent linking them to the 3-month primary endpoint.

Finally, the planning assumptions describe a hypothetical two-arm illustration rather than the enrolled single-group design. The record does not report a protocol-based sample-size justification or the numerical basis and result of that illustration. These limitations are specific to what the registry record documents and should not be taken as proof that unreported analyses or details do not exist elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study to Evaluate Preemptive Therapy in Hepatitis C (HCV) Organ Transplant Recipients — NCT04508907.
• Registry record last updated 2026-10-29; status last verified 2026-10.
• Results first posted 2026-10-29.
• 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 a completed Phase 4 pilot study sponsored by Mayo Clinic, with enrollment of 227. It evaluates preemptive combination therapy among HCV-seronegative kidney, heart, lung and/or pancreas recipients of organs from HCV-viremic donors. The design is single-group, allocation is listed as NA, and masking is listed as none.

The primary endpoint is the percentage of participants who did not become HCV viremic at 3 months. Its observed value and a statistical analysis are not reported in the registry record. The safety entries list 0 affected among 227 at risk for serious adverse events, 0 affected among 227 at risk for other adverse events, and 8 deaths. The record does not report attribution or further details for the deaths.