This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Study on the Correlation Between Interleukin 28B Genotypes With Clinical and Demographic Characteristics in Treatment-Naïve and Treatment-Experienced Patients With Chronic Hepatitis C (NCT01675427), a non-randomized phase 4 study. The primary outcome is Number of Participants With Interleukin 28B (IL28B) Genotype rs12979860 by Cirrhosis Status and Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Genotype: Treatment-Naive.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01675427 |
| Phase | Phase 4 |
| Condition | Hepatitis C, Chronic |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 4766 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Hoffmann-La Roche |
| Results posted | Yes |
2. Clinical Question
Population
People with chronic hepatitis C, including treatment-naïve and treatment-experienced participants. The registry summary also says the study included patients with HIV co-infection. The primary outcome analysis is restricted to participants who had not received prior treatment for chronic hepatitis C. The number analyzed in each HCV RNA genotype category is not reported in the registry record.
Intervention
Interleukin 28B testing at a study visit, using blood sampling to determine IL28B genotype. The study evaluates associations with patient and disease characteristics; it is not described as assigning a hepatitis C treatment.
Comparator
No randomized comparator or separate control group is identified. The study is listed as nonrandomized and single-group. Treatment-naïve and treatment-experienced participants are distinct analysis populations, not randomized treatment arms.
Primary question
Among treatment-naïve participants, how many had each recorded IL28B genotype rs12979860 category across cirrhosis-status and HCV RNA genotype categories? Cirrhosis status was classified as “Cirrhosis/transition to cirrhosis” or “No cirrhosis.” The registry record describes the planned cross-classification but does not report the resulting participant counts.
3. Trial Design
The registry identifies this as a phase 4, nonrandomized, single-group study with no masking. Its official title describes an international, multicenter evaluation of IL28B genotype in relation to demographics and disease characteristics among people with chronic hepatitis C. Enrollment is listed as 4766, and the study status is completed. The listed start was 2011-08 and primary completion was 2013-10.
The study summary describes a single study visit for testing. Blood sampling at that visit was used to determine IL28B genotype. HCV RNA genotype and cirrhosis status were drawn from medical records. The cirrhosis classification relied on a previous biopsy or noninvasive assessment captured before treatment, if applicable. The primary outcome applies to treatment-naïve participants; other listed outcomes separately describe treatment-naïve and treatment-experienced groups.
The study is not a randomized comparison of treatment strategies. The intervention is listed as IL28B testing, and the record does not describe an assigned therapeutic intervention or an untreated control arm. Therefore, its design addresses distributions and associations among measured characteristics, rather than a causal contrast between treatments. The sponsor is Hoffmann-La Roche. Details such as the number of participating centers, the statistical analysis plan, and a sample-size justification are 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.
Overall Study
| Stage | Participants With Chronic Hepatitis C (CHC) |
|---|---|
| STARTED | 4766 |
| COMPLETED | 4732 |
| NOT COMPLETED | 34 |
Reasons for not completing this period:
| Reason | Participants With Chronic Hepatitis C (CHC) |
|---|---|
| Withdrawal by Subject | 7 |
| Participant Refused Sample Collection | 18 |
| Sample not Collected by Mistake | 2 |
| Lost to Follow-up | 5 |
| Other | 2 |
Analysis population for the primary outcome, as defined in the registry: Core Analysis Population (Treatment-Naive): Only participants who had not received prior treatment for CHC were included in the analysis; n = number of participants analyzed within each HCV RNA genotype category.
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: Core Analysis Population: All participants enrolled who had a blood sample drawn for genotyping with available data for the primary variables, and who met all eligibility criteria for analysis.
| Characteristic | Unit | Participants With CHC |
|---|---|---|
| Participants analysed | 4616 | |
| Age, Continuous | years | 49.1 (SD 12.87) |
| Sex: Female, Male: Female | Participants | 2043 |
| Sex: Female, Male: Male | Participants | 2573 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Interleukin 28B (IL28B) Genotype rs12979860 by Cirrhosis Status and Hepatitis C Virus (HCV) Ribonucleic Acid (RNA) Genotype: Treatment-Naive, measured over Study Visit 1 (single study visit).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of treatment-naïve participants with IL28B genotype rs12979860, classified by cirrhosis status and HCV RNA genotype. It is recorded at Study Visit 1, described as a single study visit. This is a count endpoint: it describes how many participants fall into each combination of the recorded categories, rather than measuring a change over time or a treatment response.
The listed HCV RNA genotype categories are Genotype 1 (G1), Genotype 2 (G2), Genotype 3 (G3), Genotype 4 (G4), and all other genotypes (Other). Cirrhosis status is grouped as “Cirrhosis/transition to cirrhosis” or “No cirrhosis.” Genotype information came from study blood sampling; the other two classifications came from medical records, with cirrhosis status based on prior biopsy or noninvasive assessment when applicable.
Such cross-classification can describe whether genotype counts differ across clinical subgroups. It does not, by itself, establish that IL28B genotype caused a disease characteristic or predicts an individual’s outcome. The registry record does not report the observed counts for this endpoint, so the size or pattern of any association cannot be assessed from the record details available.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record specifies a descriptive primary outcome: counts of treatment-naïve participants with IL28B genotype rs12979860, grouped by cirrhosis status and HCV RNA genotype. It does not report those counts, the distribution of IL28B genotype categories, or a statistical estimate of association. Consequently, the direction, magnitude, and precision of any relationship between genotype and the recorded clinical characteristics are not reported in the registry record.
The endpoint is organized around participant counts within categories. Such counts can help describe how characteristics are distributed in a study population, but their interpretation depends on knowing how many participants were assessed and analyzed in each category. The registry definition notes that the number analyzed varies within each HCV RNA genotype category, but the corresponding category-specific denominators are not reported in the registry record. Without those denominators and the observed counts, comparisons of raw counts across categories would not establish differences in proportions.
The study also lists outcomes involving another IL28B variant, rs8099917, METAVIR liver inflammation grade, HCV RNA genotype, and gender, with separate outcomes for treatment-naïve and treatment-experienced participants. Those listed aims indicate a broad descriptive scope, but numerical results for them are not reported in the registry record. The number of outcome measures is 94 and the number of analyses is 382; those counts alone do not convey the findings or the strength of evidence for any particular association.
Because this is nonrandomized and single-group, it does not provide a randomized treatment contrast. Observed relationships, if available, would need interpretation in light of the characteristics used to define the groups and any other relevant factors. The registry record does not report adjusted estimates, confidence intervals, p-values, or a statistical model for the primary outcome. Precision and statistical compatibility with no association therefore cannot be judged from the recorded information.
The study summary describes one testing visit and the use of medical-record information for HCV RNA genotype and cirrhosis status. That design captures classifications at a study visit rather than reporting a longitudinal clinical outcome. The primary endpoint should consequently be read as a description of genotype and disease-characteristic categories, not as evidence of a treatment effect, disease progression, or clinical benefit.
9. Statistical Methods Explained
What does a count endpoint convey?
In general, a count endpoint records how many participants meet a specified classification. Here, the primary outcome concerns participants with IL28B genotype rs12979860 within categories defined by cirrhosis status and HCV RNA genotype. Counts describe the size of the observed groups. They are not automatically proportions, rates, or comparisons of risk. To interpret a count against another group, the relevant denominators and a suitable comparison method are needed. The registry record does not report the observed counts or the denominators for the primary outcome categories.
Why classify participants by several characteristics?
In general, cross-classifying measurements can describe whether a characteristic appears with different frequency across subgroups. For this study, the primary outcome combines IL28B genotype with HCV RNA genotype and cirrhosis status. The HCV RNA categories are G1, G2, G3, G4, and Other; cirrhosis status is recorded as “Cirrhosis/transition to cirrhosis” or “No cirrhosis.” Such categories make the clinical question more specific, but they can also create smaller subgroups. A count in a small subgroup may be imprecise, especially when the denominator is limited. The relevant subgroup sizes are not reported in the registry record.
What does the data structure say about measurement?
The IL28B genotype was determined from blood sampling at the study visit. HCV RNA genotype and cirrhosis status were obtained from medical records. The record says cirrhosis status relied on a previous biopsy or noninvasive assessment captured before treatment, if applicable. In general, variables drawn from different sources can have different measurement processes. A study interpretation should consider how consistently categories were determined and whether records were complete. The registry record does not report further details about classification procedures, central review, or agreement between assessors.
Why does over-dispersion matter in general?
Over-dispersion is a general issue for count data when the variability exceeds what a chosen statistical model expects. If present and ignored, uncertainty estimates from that model can be too small, making results appear more precise than they are. That concept is relevant to some count-model analyses, but the registry record does not report a model, dispersion estimate, or whether over-dispersion was assessed. The primary outcome is described as a number of participants, and no model-based estimate is reported.
How should statistical uncertainty be read?
In general, a confidence interval gives a range of values compatible with data and a specified analysis procedure, while reflecting sampling uncertainty. A p-value, when used, summarizes how inconsistent data are with a specified null hypothesis under the model assumptions; it is not a measure of clinical importance. Neither can be interpreted without the estimate, analysis method, and relevant assumptions. The registry record does not report a confidence interval, p-value, or test for the primary outcome. No precision statement about an association can therefore be made from the record.
What do the analysis counts mean?
The registry lists 94 outcome measures and 382 analyses. These are counts of listed outcomes and analyses, not measures of effect or evidence. A wide set of analyses can raise multiplicity concerns: when many hypotheses are examined, the chance of at least one apparently notable result can increase. In general, prespecifying the primary question and describing any adjustment strategy helps readers distinguish confirmatory from exploratory analyses. The registry record does not report a multiplicity adjustment strategy or enough analysis detail to determine how the listed analyses were interpreted.
Are recalculated results available?
No recalculated effect estimate or sample-size planning estimate is reported in the registry record. General planning calculations based on an observed effect require that effect and specified assumptions; their purpose is to illustrate planning, not to show observed power. The record states assumptions for a planning illustration, including a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect defined as a fraction of the observed effect. However, the outcome is a nonrandomized, single-group study rather than a two-arm randomized comparison, and no numerical planning estimates or observed effect are reported in the registry record. Those assumptions should not be mistaken for the study’s own design justification.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 94 outcome measures and 382 analyses. The outcomes cover several IL28B variants, clinical characteristics, and separate treatment-naïve and treatment-experienced populations. Examining many outcomes can create multiplicity: in general, the more hypotheses tested, the greater the possibility of a seemingly notable finding arising by chance. The registry record does not report a prespecified hierarchy beyond identifying the primary outcome, a multiplicity adjustment, or how exploratory analyses were distinguished from confirmatory ones.
The primary analysis population is described as treatment-naïve participants who had not received prior treatment for chronic hepatitis C. The record says the number analyzed is specific to each HCV RNA genotype category. It does not report the category-specific analysis counts or explain how missing genotype, cirrhosis, or medical-record information was handled. Missing-data methods, imputation, and sensitivity analyses are not reported in the registry record.
Accordingly, the enrolled total of 4766 should not be treated as the denominator for every endpoint category. Enrollment and analysis-population counts can differ, and the registry record does not provide the primary endpoint’s complete denominators. No inferential results or precision estimates are reported for assessing the effects of missingness or multiplicity.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Participants With CHC | 0 | 4733 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Participants With CHC | 0 of 0 |
The registry reports 4733 participants at risk in the “Participants With CHC” group and 0 serious adverse events. No serious adverse event terms are listed. These figures describe the safety entries recorded for this group; they do not establish that all participants had complete safety observation or that events could not have occurred outside the recorded reporting period.
The study summary describes a single visit for testing, while the registry record does not specify the safety observation window or provide additional detail about how adverse events were collected. The record also does not report a comparative safety analysis. Since the study is nonrandomized and single-group, the safety entries do not form a comparison between assigned treatment groups. They should be read as registry-reported counts, not as evidence about the safety of a hepatitis C treatment.
12. What the Result Does, and Does Not, Mean
The study’s question concerns how IL28B genotype is distributed alongside selected clinical and demographic characteristics in people with chronic hepatitis C. The primary outcome focuses on rs12979860 among treatment-naïve participants, cross-classified by cirrhosis status and HCV RNA genotype. The registry record identifies these measurements and classifications, but does not report the observed participant counts or an estimate of association. It therefore does not establish what pattern was observed or how precisely that pattern was estimated.
Even if subgroup distributions are available from other sources, a descriptive association would not by itself show that genotype caused a clinical characteristic. The study is listed as nonrandomized and single-group, and its primary endpoint is a count at a study visit rather than a randomized treatment outcome. Confounding, participant selection, incomplete records, and classification differences are general considerations for interpreting observational associations; the registry record does not report analyses addressing them.
The record also does not report a treatment-effect estimate, a comparison of clinical outcomes between assigned interventions, or evidence that genotype testing changes patient outcomes. The study summary describes testing and evaluation of correlations, not a trial of a therapeutic strategy. The registry information therefore supports describing the study’s objective and measurement plan, but not drawing conclusions about treatment effectiveness or individual prognosis.
More complete interpretation would require the outcome counts, subgroup denominators, analysis methods, uncertainty estimates, and details of missing-data handling. Those items are not reported in the registry record. The reported enrollment total and completion status do not substitute for endpoint results.
13. Why This Trial Matters Statistically
This study is statistically notable for its broad descriptive question: relating IL28B genotype to disease characteristics and demographics across treatment-naïve and treatment-experienced chronic hepatitis C populations. Its primary endpoint illustrates how a genetic marker can be cross-classified with clinically relevant characteristics such as cirrhosis status and HCV RNA genotype. Such designs can characterize who was measured and how categories are distributed, without requiring a treatment assignment.
The record also highlights important interpretive distinctions. Enrollment is not the same as the endpoint-specific analysis population, and raw counts are not equivalent to proportions or adjusted associations. The registry states that analysis counts vary by HCV RNA genotype category, so denominators matter when comparing categories. Because those denominators and the observed primary outcome counts are not reported in the registry record, the association cannot be quantified from its information.
The breadth of listed outcomes—94 outcome measures and 382 analyses—also makes transparent reporting of analysis plans and multiplicity procedures important. In general, readers need to know which questions were primary, what comparisons were planned, and how uncertainty was assessed. Those analysis details are not reported in the registry record. The study thus provides a useful example of why a registry description of objectives and outcome definitions is distinct from a complete statistical account of results.
14. 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 describes the primary outcome but does not report its observed counts, category-specific denominators, or statistical estimates. As a result, the direction and magnitude of any association cannot be evaluated, and its precision cannot be assessed. The number enrolled, 4766, does not identify how many participants contributed to each primary outcome category.
The study is nonrandomized and single-group, so it is not designed as a randomized comparison of interventions. The primary outcome is descriptive and based on classifications recorded at a study visit. The registry record does not report adjusted analyses or methods for addressing potential confounding. It also does not report the missing-data strategy, the extent of missing information, or sensitivity analyses.
Measurement sources differ: IL28B genotype was determined from blood sampling, whereas HCV RNA genotype and cirrhosis status were obtained from medical records. Although the record describes the basis for cirrhosis classification, it does not report additional information about consistency of assessments or classification error. The study summary mentions treatment-naïve and treatment-experienced participants and HIV co-infection, but detailed subgroup results are not reported in the registry record.
Finally, the registry lists many outcomes and analyses but does not report a multiplicity strategy or a full statistical analysis plan. Numerical results, confidence intervals, and p-values for the primary outcome are not reported in the registry record. These omissions limit assessment of both the findings and their uncertainty.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study on the Correlation Between Interleukin 28B Genotypes With Clinical and Demographic Characteristics in Treatment-Naïve and Treatment-Experienced Patients With Chronic Hepatitis C — NCT01675427.
- Registry record last updated 2015-08-26; status last verified 2015-08.
- Results first posted 2015-06-08.
- 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.
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18. Record Summary
NCT01675427 is a completed phase 4, nonrandomized, single-group study sponsored by Hoffmann-La Roche. It enrolled 4766 participants and evaluated IL28B genotype in relation to demographics and disease characteristics in chronic hepatitis C, including treatment-naïve and treatment-experienced participants and patients with HIV co-infection. The summary describes a single study visit for testing.
The primary outcome counts treatment-naïve participants with IL28B genotype rs12979860 across cirrhosis-status and HCV RNA genotype categories. The registry record describes the outcome and analysis population but does not report the resulting counts, denominators, or statistical estimates. It lists 94 outcome measures and 382 analyses. The safety entry reports 0 serious adverse events among 4733 participants at risk. The registry record does not report a detailed statistical analysis plan, missing-data methods, or a multiplicity adjustment strategy.