Hepatitis C Treatment to Prevent HIV, Initiate Opioid Substitution Therapy, and Reduce Risky Behavior: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hepatitis C Treatment to Prevent HIV, Initiate Opioid Substitution Therapy, and Reduce Risky Behavior (NCT03221309), a registered phase not stated study. The primary outcome is Hepatitis C Virus (HCV) Cure (Sustained Virologic Response).

2. Clinical Question

The study title frames the care model around HCV treatment, HIV prevention, opioid substitution therapy, and risk behavior. The registry description focuses on evaluating a model of HCV care for people with ongoing injection drug use. It says participants would receive direct-acting antivirals and would concomitantly be offered PrEP and buprenorphine when clinically indicated. These are components of the care approach, not randomized treatment assignments against a control group.

The record lists uptake and retention on HIV PrEP and uptake and retention in a buprenorphine program as secondary outcomes. The primary question is therefore narrower than the full set of care-model aims: it concerns the number of participants meeting the stated HCV cure definition. The registry record does not report the observed primary outcome result, nor does it report estimates for the secondary outcomes. It therefore cannot answer from the posted results whether uptake, retention, or cure differed across groups or phases.

3. Trial Design

NCT03221309 is registered as a completed, open-label, non-randomized, observational pilot study sponsored by the University of Maryland, Baltimore. The listed enrollment is 198. The recorded study start is 2017-05-01, and the primary completion date is 2021-01-22. The registry describes an evaluation of a care model rather than a randomized comparison of assigned treatments.

The intervention is named as an evaluation of a model of care for HCV-infected adults with ongoing opioid misuse. In the brief description, direct-acting antivirals were to be given as per standard of care. Participants would also be offered HIV PrEP and buprenorphine for opioid use disorder when clinically indicated. The record does not describe a control intervention or a randomized allocation procedure. It explicitly cautions that the arms are not a like-for-like control comparison, and allocation is not stated.

The arm description distinguishes two phases. Phase 1 is described as the first 100 enrolled participants, with HCV infection, ongoing injection drug use with opioids, and 3 months of screening. Phase 2 is described as enrolled participants 101-200, with HCV infection and ongoing misuse of non-prescription opioids within twelve months of screening. The record does not report phase-specific enrollment or explain how the phase change affected care delivery or analysis. The listed enrollment is 198; the phase labels do not establish the number analyzed in either phase.

The primary outcome is HCV cure, recorded as a participant count and assessed over a 24 weeks timeframe. Secondary outcomes concern uptake and retention for PrEP and buprenorphine. The record lists five outcome measures and reports no analyses. Completion status describes the registry status; it does not itself indicate that outcome results are available.

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 Hepatitis C Virus (HCV) Cure (Sustained Virologic Response), measured over 24 weeks.

The primary endpoint is Hepatitis C Virus cure, identified as sustained virologic response. It is measured as a count of participants and defined in the registry record as an undetectable HCV viral load 12 weeks after the end of treatment. The listed endpoint timeframe is 24 weeks.

This endpoint uses a laboratory-based definition tied to viral load after treatment, rather than a subjective assessment of symptoms or behavior. In general, defining an endpoint in advance gives researchers a consistent outcome to measure across participants. A count can describe how many participants meet the endpoint definition, but interpretation also depends on the denominator, follow-up completeness, and the analysis population. Those details are not reported for the primary outcome in the registry record.

The registry record does not report the number of participants who achieved sustained virologic response, an estimate with uncertainty, or a comparison between groups. The endpoint definition alone does not establish how many participants met it. Nor does the timeframe description establish whether every participant completed the required assessment. Follow-up completeness and the handling of missing viral-load results are not reported in the registry record.

The endpoint addresses HCV virologic status after treatment. It does not, by itself, measure HIV prevention, PrEP uptake or retention, buprenorphine uptake or retention, or changes in risky behavior. Those topics appear in the study aims or secondary outcomes, but the primary endpoint should be interpreted as a measure of HCV cure under the stated definition.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a binary participant-level event summarized as a count: whether a participant met the HCV cure definition. The event is an undetectable HCV viral load 12 weeks after treatment ended. The record gives a 24 weeks timeframe. It does not report an analysis estimate, confidence interval, p-value, or primary-outcome count.

What does a count endpoint describe?

In general, a count of participants with an event records how many people met a prespecified outcome definition. By itself, a count does not show the event frequency unless its denominator is also known. A proportion can help describe frequency, but it requires a clearly defined analysis population and an account of missing outcome data. The registry record does not report the primary endpoint denominator or how participants without a recorded viral-load result were handled.

For a binary endpoint, researchers may compare event proportions between groups or estimate an event probability within a group. General methods for these analyses depend on the study design, the number and structure of comparison groups, and the analysis plan. In this study, the registry describes a non-randomized observational design and warns that the arms are not a like-for-like control comparison. Allocation is not stated. A numerical contrast between groups, if reported, would therefore need careful interpretation and could not be treated as a randomized causal effect.

What does a confidence interval add?

In general, a confidence interval expresses the statistical uncertainty around an estimate under the assumptions of the method used. It does not guarantee that the true value lies within the interval, nor does it resolve biases from study design or incomplete follow-up. A narrow interval can indicate greater precision for the modeled estimate, while a wide interval indicates greater uncertainty. No confidence interval for the primary endpoint is reported in the registry record, so its statistical precision cannot be assessed.

What can a significance test establish?

In general, a significance test evaluates how compatible observed data are with a specified statistical null model. A p-value is not the probability that a treatment works, and statistical significance is not equivalent to clinical importance. Testing also relies on choices about the outcome, comparison, model, and analysis population. The registry record reports no analyses or p-values for the outcomes. No conclusion about statistical significance can be drawn from the registered design details alone.

The record notes a planning-illustration framework based on an observed effect. Its stated assumptions include 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. For time-to-event planning, the stated convention is a total event count; for other planning illustrations, it is participants per arm. These are planning assumptions, not a report of the trial's own design justification or an observed power calculation. The record does not provide numerical planning results in the details available for this analysis. Planning calculations cannot be read as evidence that the study had a particular probability of finding an effect after the data were collected.

In general, over-dispersion means that observed variability is greater than a statistical model expects. It matters when the model assumes less variability than the data contain, because uncertainty estimates and tests may then be too optimistic. The primary endpoint is recorded as a binary count, and no dispersion value or model is reported. It would be inappropriate to assert that over-dispersion occurred or that a particular correction was used.

The study's non-randomized design also affects method selection and interpretation. Randomization, when used, can balance measured and unmeasured participant characteristics on average across assigned groups. An observational comparison does not have that design protection. Statistical adjustment can address measured differences under specified assumptions, but it cannot automatically remove unmeasured confounding. The registry record does not report covariate adjustment, a model specification, or a statistical analysis plan. Thus, no adjustment method or causal estimand should be attributed to this study from the registry record.

Finally, the endpoint is assessed after treatment, so a complete analysis requires clarity about who was eligible for assessment, how the observation window was applied, and what happened when follow-up was incomplete. General approaches might treat missing outcome data differently, and those choices can alter estimates. The registry record does not report missing-data methods or analysis populations. These omissions prevent an independent appraisal of the primary endpoint analysis, even though the endpoint definition itself is stated.

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("Adults Infected With Hepatitis C Virus (HCV)")
n      <- c(198)
events <- c(158)
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  Adults Infected With Hepatitis C Virus (HCV)  198  158  79.8  73.5  85.2  73.7  84.8  73.7  84.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists the primary HCV cure outcome and four secondary outcomes: uptake of HIV PrEP, retention on HIV PrEP, uptake of buprenorphine, and retention in a buprenorphine program. It reports five outcome measures and no analyses. Results, hypothesis tests, and a multiplicity strategy are not reported in the registry record.

In general, multiplicity arises when researchers examine several outcomes, comparisons, or time points. If each is tested separately, the chance of at least one apparently unusual result can increase. A prespecified hierarchy or an adjustment to testing can address some multiplicity concerns, while descriptive reporting may not require the same inferential framework. The registry record does not describe whether outcomes were ranked, whether any adjustment was planned, or which outcomes were intended for confirmatory inference. No claim about multiplicity control can therefore be made.

Missing-data methods are also not reported. The record does not state how participants without an endpoint assessment were handled, whether follow-up was complete, or whether missingness differed by phase or outcome. These details matter because a count of events is interpretable only alongside a defined analysis population and an account of unavailable outcomes.

The analysis populations are not reported in the registry record. There is no stated intention-to-treat, per-protocol, or other analysis set, and no reported flow from enrollment to outcome assessment. The phase descriptions do not establish how many participants contributed to each outcome analysis. Without these details, the denominator and selection of participants underlying any result cannot be evaluated.

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 5% reporting threshold.

The registry safety entry is for the group titled Adults Infected With HCV. It lists 198 participants at risk for serious adverse events and 0 participants affected by serious adverse events. It also lists 198 at risk for other adverse events and 0 participants affected by other adverse events. The death count is 14.

These are registry-record counts, not a comparison of safety between randomized groups. The record does not describe the causes, timing, or relationship of the deaths to treatment, nor does it give further event details in the listed serious-event terms. A count of 0 affected participants in the reported categories should be read as the registry entry's reported figure; it does not establish that no unrecorded event occurred or explain how events were collected and classified.

The death count should be kept distinct from the serious and other adverse-event counts. The registry record does not say whether deaths were treatment-related, when they occurred, or how they were distributed by phase or follow-up status. No causal safety conclusion can be drawn from these figures alone. The absence of a like-for-like control group further limits comparative interpretation.

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

The registry record establishes that NCT03221309 was completed as an open-label, non-randomized observational pilot with a registered enrollment of 198. It describes a care model centered on direct-acting antiviral treatment for HCV, alongside offers of HIV PrEP and buprenorphine when clinically indicated. It defines HCV cure as an undetectable viral load 12 weeks after treatment, with a 24 weeks endpoint timeframe.

Those design and endpoint details do not establish the observed outcome. The registry record does not report the primary endpoint count, denominator, estimate, confidence interval, or statistical test. It also does not report results for the listed secondary outcomes. Consequently, no estimate of cure frequency, PrEP uptake or retention, or buprenorphine uptake or retention can be drawn from the registry record. The title and objectives express aims; they are not outcome findings.

The study's observational, non-randomized design also means that an apparent association, if one were reported, would not automatically demonstrate that the care model caused it. Participant characteristics, care decisions, and the phase-specific eligibility descriptions could matter to comparisons. The registry record says the arms are not a like-for-like control comparison and does not state allocation. It also does not report an adjustment strategy that might address measured differences.

The safety entry reports 0 participants affected by serious adverse events, 0 affected by other adverse events, and 14 deaths. It does not report the causes or timing of deaths or establish their relationship to study treatment. These counts should be described as recorded, not interpreted as evidence about causation or comparative safety.

In general, a result is most informative when its estimate is accompanied by an uncertainty interval, a clear denominator, and an explanation of who was analyzed and how missing outcomes were handled. Those features are not reported for the primary outcome. The strongest supported conclusion is therefore about what the study set out to evaluate and how its primary endpoint was defined—not whether the model achieved its aims.

14. Why This Trial Matters Statistically

This trial is statistically notable as an observational evaluation of a multi-component care model, rather than a randomized efficacy comparison. The care described includes standard-of-care direct-acting antivirals and offers of PrEP and buprenorphine when clinically indicated. That combination raises an important interpretation issue: the primary endpoint concerns HCV cure, while other listed outcomes concern uptake and retention in additional services. These endpoints represent different questions and should not be treated as interchangeable evidence of a single effect.

The registry also describes two phases with different eligibility wording. Phase 1 concerns ongoing injection drug use with opioids and 3 months of screening; Phase 2 concerns ongoing misuse of non-prescription opioids within twelve months of screening. These descriptions matter statistically because changes in eligibility or context can make comparisons across phases difficult to interpret. The record does not report phase-specific enrollment or an analysis of phase differences.

The primary outcome is clinically and statistically specific: a participant count based on an undetectable HCV viral load 12 weeks after treatment, within a 24 weeks timeframe. Yet the registry record does not report the outcome analysis. This highlights the distinction between a well-defined endpoint and a reported result. Without the count, denominator, uncertainty, and analysis population, readers cannot judge the precision or robustness of an estimated outcome.

The record's explicit caution that the arms are not a like-for-like control comparison is also central. It guards against reading a difference between groups as if it arose from randomized assignment. For biostatistical interpretation, design information and analysis results must be read together; neither the completed status nor the stated enrollment supplies missing outcome evidence.

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 important limitation for interpreting outcomes is that the registry record does not report primary or secondary outcome analyses. It provides no primary event count, denominator, estimate, uncertainty interval, or statistical test. The listed enrollment of 198 therefore cannot be treated as the number with an observed primary endpoint or as the analysis population.

The design is open-label, non-randomized, and observational. The registry record states that allocation is not stated and that the arms are not a like-for-like control comparison. As a result, it does not support a straightforward randomized treatment contrast. The record also does not describe statistical adjustment or a prespecified analysis plan, so the handling of potential differences among participants cannot be assessed.

The two phase descriptions use different eligibility language. Phase 1 refers to ongoing injection drug use with opioids and 3 months of screening; Phase 2 refers to misuse of non-prescription opioids within twelve months of screening. The record does not report phase-specific enrollment, whether eligibility changed in practice, or how phase was incorporated into any analysis. These details limit interpretation of comparisons across phases.

Additional reporting gaps include the absence of analysis populations, missing-data methods, outcome denominators, and an explanation of how follow-up was completed. The record does not report a trial-specific sample-size justification. The safety entry gives event and death counts but not causes, timing, or relationships to treatment. These limitations constrain both efficacy and safety interpretation and should not be filled by assumptions.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Hepatitis C Treatment to Prevent HIV, Initiate Opioid Substitution Therapy, and Reduce Risky Behavior — NCT03221309.
• Registry record last updated 2026-05-04; status last verified 2026-04.
• Results first posted 2024-09-03.
• 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

NCT03221309 is a completed, open-label, non-randomized observational pilot sponsored by the University of Maryland, Baltimore. Its registered enrollment is 198. The recorded start date is 2017-05-01, and the primary completion date is 2021-01-22.

The study evaluates a model of HCV care for adults with HCV and ongoing opioid-related risk. Direct-acting antivirals were to be used as per standard of care, with PrEP and buprenorphine offered when clinically indicated. The primary outcome is a participant count for HCV cure, defined as an undetectable viral load 12 weeks after treatment, with a 24 weeks timeframe. Listed secondary outcomes concern uptake and retention for PrEP and buprenorphine.

The registry record reports no analyses and does not report primary or secondary outcome results. It cautions that the arms are not a like-for-like control comparison. Safety entries list 0 participants affected by serious adverse events, 0 affected by other adverse events, and 14 deaths; causes and timing are not reported.