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 Pegylated Interferon Alpha-2b in Early Primary Myelofibrosis (NCT01758588), a randomized phase 2 study. The primary outcome is Clinical Improvement.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01758588 |
| Phase | Phase 2 |
| Condition | Myelofibrosis |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Weill Medical College of Cornell University |
| Results posted | Yes |
2. Clinical Question
Population
People newly diagnosed with untreated early-stage primary myelofibrosis, as described in the registry summary. The condition is listed as myelofibrosis, and the enrollment was 8 participants. The record does not provide additional eligibility details or a breakdown of participant characteristics.
Intervention
The intervention arm is described as peginterferon alfa-2a administered at a dose of 50 micrograms once a week for up to 3 years. Elsewhere, the study summary calls the drug PEGINTRON, also known as pegylated interferon alfa 2b. The drug naming is inconsistent within the registry record.
Comparator
The observation arm is described as close monitoring for disease progression with no intervention. The study summary characterizes this approach as “watch and wait” or best supportive care, with treatment initiated only if the disease progresses. No further details of monitoring or supportive care are reported in the registry record.
Primary question
The primary endpoint is clinical improvement at one year. The study asks whether participants meet the registry’s specified improvement criteria in the absence of disease progression and without assignment of complete response or partial response. The registry record does not report the arm-level clinical-improvement counts or a comparative effect estimate, so it does not establish what the comparison showed.
3. Trial Design
This is a randomized Phase II clinical trial with no masking. The registry lists a crossover model and an enrollment of 8. Its title describes a randomized controlled trial of pegylated interferon alpha-2b in early primary myelofibrosis. The brief summary describes a comparison between drug treatment and observation, while the arm descriptions identify an observation arm and a peginterferon arm.
The record does not report the crossover sequence, the timing of any treatment switch, the length of any washout, or how outcomes were attributed to treatment periods. These details matter when interpreting a crossover design because the observations may depend on treatment order, time, and any carryover from an earlier treatment period. Those considerations are general features of crossover trials; the registry record does not state how they were addressed in this study.
The study status is terminated. The start is listed as 2013-01 and primary completion as 2017-06. The reason for termination is not reported in the registry record. No conclusion about why recruitment or follow-up ended can be drawn from the status alone.
The intervention naming is not consistent across the record: the title and summary refer to pegylated interferon alpha-2b or PEGINTRON, while the intervention and arm description say peginterferon alfa-2a. The record does not explain this difference. The stated dose and schedule are 50 micrograms once a week for up to 3 years. No additional treatment administration details are reported.
The design establishes the intended comparison, but it does not by itself supply evidence about the treatment effect. Enrollment was 8, and the registry record does not provide the primary endpoint counts by arm or a comparative estimate. Results for the listed secondary outcomes, progression-free survival and overall survival, are also 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: Patients were randomized to either the treatment arm or the control arm of the study with a 2:1 allocation ratio. 8 patients were enrolled. No patients crossed over from observation to treatment.
Overall Study
| Stage | Treatment Arm | Observation Arm |
|---|---|---|
| STARTED | 5 | 3 |
| COMPLETED | 5 | 3 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | Treatment Arm | Observation Arm | Total |
|---|---|---|---|---|
| Participants analysed | 5 | 3 | 8 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 2 | 3 |
| Age, Categorical: >=65 years | Participants | 4 | 1 | 5 |
| Age, Continuous | years | 71.9 (SD 6.2) | 69.1 (SD 5.5) | 69.9 (SD 7.1) |
| Sex: Female, Male: Female | Participants | 2 | 2 | 4 |
| Sex: Female, Male: Male | Participants | 3 | 1 | 4 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 3 | 3 | 6 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 2 | 0 | 2 |
| Region of Enrollment: United States – Weill Cornell Medicine | Participants | 4 | 2 | 6 |
| Region of Enrollment: United States – Emory University | Participants | 1 | 1 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Clinical Improvement, measured over One year.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is clinical improvement, measured as a count of participants, with a timeframe of one year. The definition permits several kinds of improvement rather than requiring a single laboratory or clinical change. A response is validated only if it lasts for no fewer than 8 weeks, and it must occur in the absence of disease progression and without complete response or partial response assignment.
The listed criteria include a minimum 20-g/L increase in hemoglobin or becoming transfusion independent, when baseline hemoglobin is less than 100 g/L. For spleen findings, the definition includes a minimum 50% reduction in palpable splenomegaly when the spleen is at least 10 cm at baseline, or a spleen palpable at more than 5 cm at baseline becoming not palpable. It also includes a minimum 100% increase in platelet count with an absolute platelet count of at least 50 000 109/L for participants whose baseline platelet count is below 50 109/L, and a minimum 100% increase in absolute neutrophil count with an ANC of at least 0.5 109/L for participants whose baseline ANC is below 1 109/L.
A composite endpoint can capture improvement through different disease features, but interpretation depends on the exact definition and participant-level eligibility for each criterion. The registry record gives the definition but does not report how many participants met it in either arm. The endpoint’s clinical-improvement counts and comparative result are therefore not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a randomized comparison of peginterferon and observation, but it does not provide the arm-level result for the primary endpoint, clinical improvement at one year. Although the endpoint definition is detailed, the number of participants meeting it in each arm and a between-arm estimate are not reported in the registry record. The primary outcome is also identified as having several categories or time points and is not reduced to one comparison. The available record therefore does not support a numerical estimate of the difference between the assigned approaches.
There is likewise no reported confidence interval or p-value for the primary comparison in the registry record. A confidence interval, in general, describes the range of effect estimates compatible with the data under a specified statistical procedure. Its width conveys precision: wider intervals indicate less precise estimation. Without a reported estimate and interval, the direction and precision of the primary result cannot be assessed. The absence of a reported comparison should not be interpreted as evidence that the arms were equivalent.
The enrollment was 8. This small total makes the amount of information available for estimating arm differences limited, even before considering the missing endpoint results. General statistical reasoning indicates that estimates from small studies can be imprecise and sensitive to the outcome of individual participants. However, no study-specific uncertainty measure is reported, and no effect size should be inferred from the enrollment or from the safety counts.
The registry lists one analysis, but does not describe its method, the population included, or how the crossover structure was handled. Random allocation is part of the design, but the record does not describe the allocation procedure or any adjustment in the analysis. The lack of masking is reported; the consequences for assessment of a composite clinical endpoint depend on how the endpoint was evaluated, which is not reported in the registry record.
Progression-free survival and overall survival are listed as secondary outcomes. Their definitions, analyses, event counts, and results are not reported in the registry record. The safety information is limited to the serious and other adverse-event counts described separately; it does not supply the missing primary efficacy comparison. Taken together, the record describes what the study intended to compare and what clinical improvement meant, but does not report enough outcome information to quantify the primary treatment contrast.
9. Statistical Methods Explained
The registry describes the primary outcome as a count of participants meeting a binary clinical-improvement definition. In general, a binary outcome classifies each participant into one of two states for the endpoint, such as meeting or not meeting its criteria. A count records how many participants meet the definition; comparing such counts between randomized arms can describe the observed contrast. The registry record does not give the arm-level counts or the method used to analyze them, so no specific effect estimate can be reconstructed from the information reported.
What can a confidence interval tell us?
In general, a confidence interval is an uncertainty summary around an estimated effect. Its limits indicate the values that remain compatible with the observed data under the interval’s statistical assumptions. An interval that spans a wide range expresses less precision than a narrower interval. The interval does not show the probability that a particular treatment effect is true. No confidence interval for the primary endpoint is reported in the registry record, so the precision of an arm comparison cannot be described.
Why does the crossover model matter?
A crossover design generally means that participants receive more than one assigned condition in a planned sequence. This structure can allow within-participant comparisons, but analysis may need to account for treatment order, period effects, and carryover. These are general methodological considerations, not claims about what occurred in this trial. Although the registry identifies a crossover model, it does not report the sequence, period schedule, washout, or analysis approach. It is therefore not possible to determine from the registry record how the crossover design contributed to the reported analysis.
What does randomization contribute?
In general, random allocation is intended to reduce systematic differences between groups at assignment. It does not guarantee that groups will be similar in every characteristic, particularly in a study with limited enrollment. This trial is listed as randomized, but the method of sequence generation, allocation concealment, and any baseline comparison are not reported in the registry record. No claim about balance between the arms can be made from the design label alone.
How should the sample-size illustration be read?
The registry’s sample-size assumptions describe a planning illustration based on the observed effect, not the trial’s own design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The illustration varies the effect to detect as a stated fraction of the observed effect. For non-time-to-event outcomes, its results are expressed as participants per arm for 80% power or other stated power levels; for time-to-event outcomes, the stated quantity is the total number of events using the Schoenfeld method. No sample-size illustration values are reported in the registry record presented for this analysis.
Such calculations are planning illustrations, not observed power. General power calculations describe the chance of detecting a specified effect under assumptions about the effect, variability, design, and analysis. They do not measure the probability that the observed finding is true, and they cannot replace an effect estimate with an uncertainty interval. Because the primary endpoint comparison is not reported, the planning illustration cannot be interpreted as a result of the randomized comparison. No sample-size justification for the original trial is reported in the registry record.
Why can over-dispersion matter?
For count outcomes, a statistical model may assume a particular relation between the average count and its variability. Over-dispersion means that the observed variability exceeds what the model assumes. If it is ignored, uncertainty estimates can be too small and statistical tests can be misleading. This is a general concept; the primary outcome is described as a participant count, and the registry does not report a count model, a dispersion estimate, or an assessment of over-dispersion. It would not be appropriate to claim that over-dispersion occurred in this trial.
The registry lists one analysis and three outcome measures, but does not identify the full analysis method or provide a statistical analysis plan. The analysis population, handling of missing outcomes, treatment of crossover periods, and adjustment for multiple outcomes are not reported in the registry record. These omissions prevent a detailed assessment of whether the analysis matched the intended design and endpoint definition.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary endpoint of clinical improvement and identifies progression-free survival and overall survival as secondary outcomes. It also reports three outcome measures and one analysis. The record does not describe whether the analyses were planned as a family of hypotheses, whether any multiplicity adjustment was used, or how the primary and secondary outcomes were prioritized beyond their labels. The approach to multiplicity is therefore not reported in the registry record.
In general, testing several outcomes can increase the chance of at least one apparently notable result arising by chance. Statistical plans may address this through prespecified testing order or adjustment procedures. No such procedure is described, and no significance tests for the outcome comparisons are reported in the registry record. The number of listed outcomes alone does not establish that a particular adjustment was required or used.
The record does not state how missing endpoint data were handled, whether every enrolled participant was included in the primary analysis, or whether analyses followed assigned treatment regardless of exposure. These are not reported in the registry record. For a crossover trial, the handling of incomplete periods and treatment changes can also affect the analysis, but the relevant details are not reported.
The primary endpoint is not reduced to one comparison because it has several categories or time points. That limitation leaves no single primary contrast to interpret. Without an analysis population, missing-data approach, and multiplicity plan, the completeness and inferential scope of the reported analysis cannot be evaluated from the registry record.
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 |
|---|---|---|---|
| Treatment Arm | 2 | 5 | 40.0% |
| Observation Arm | 0 | 3 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Treatment Arm | 0 of 5 |
| Observation Arm | 0 of 3 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Treatment Arm | 1 of 5 |
| Observation Arm | 0 of 3 |
Most frequent serious adverse event terms
| Event term | Organ system | Treatment Arm | Observation Arm |
|---|---|---|---|
| Pneumonia | Respiratory, thoracic and mediastinal disorders | 1 of 5 | 0 of 3 |
| Hypoxia | Respiratory, thoracic and mediastinal disorders | 1 of 5 | 0 of 3 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Treatment Arm | Observation Arm |
|---|---|---|---|
| Depression | Psychiatric disorders | 1 of 5 | 0 of 3 |
Serious events with the highest arm-level rate: pneumonia (20.0%), hypoxia (20.0%).
The serious adverse-event figures are reported by treatment and observation arm. In the treatment arm, 2 participants were affected among 5 at risk; in the observation arm, 0 were affected among 3 at risk. No deaths are reported in either arm. The record also lists other adverse events affecting 1 participant among 5 at risk in the treatment arm and 0 among 3 at risk in the observation arm.
Pneumonia and hypoxia are listed among the top serious terms, each at 20.0%. These percentages are reported as registry entries; the record does not provide additional event-level detail or explain whether a participant could contribute to more than one term. The serious-event counts are descriptive and based on small arm totals. They do not by themselves estimate comparative risk with precision, establish causation, or capture the full safety profile.
The registry record does not describe adverse-event collection methods, severity grading details, exposure time for each participant, or statistical comparisons. Because the study is listed as crossover, the record also does not clarify how safety events were assigned across treatment periods. These details are not reported in the registry record. The counts should therefore be read as the posted event summaries, not as a definitive comparative safety analysis.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, unmasked Phase II crossover study was intended to compare peginterferon with observation in early primary myelofibrosis. It reports an enrollment of 8 and defines clinical improvement at one year using specified blood-count and spleen-related criteria, with a minimum response duration of 8 weeks and exclusions related to progression or response assignment. It also provides limited adverse-event counts.
It does not report the primary endpoint counts by arm, a treatment-effect estimate, a confidence interval, or a p-value. Consequently, the posted information does not show the size, direction, or precision of the clinical-improvement comparison. A missing estimate is not evidence of no difference, and it cannot establish equivalence. Nor can safety counts substitute for the primary endpoint comparison.
The record also does not report results for progression-free survival or overall survival. The reason for termination is not reported in the registry record, so the termination status should not be taken as an explanation of the study’s outcome or conduct. Likewise, the record does not state whether the trial met a recruitment target or why enrollment was 8.
The appropriate interpretation is bounded: the registry describes a treatment comparison and endpoint, but its posted results do not permit a quantitative conclusion about that endpoint. The small enrollment and absence of reported comparative estimates limit what can be learned from the available data. Any broader conclusion would require information not reported in the registry record.
13. Why This Trial Matters Statistically
This trial illustrates why a registered study’s design description and outcome definition are not interchangeable with an interpretable result. The randomized comparison and clinical-improvement criteria explain the intended question, but a result requires arm-level outcome information and an analysis that yields an effect estimate. Those primary comparison details are not reported in the registry record.
The enrollment of 8 is especially important when considering precision. General statistical reasoning is that studies with limited information often produce uncertain estimates, and individual outcomes can have substantial influence. Here, no primary effect estimate or confidence interval is reported, so the degree of uncertainty cannot be quantified. The registry status and design alone cannot fill that gap.
The crossover label also highlights the need for analysis details. Treatment sequence, period structure, and handling of carryover can affect how observations should be interpreted. The record does not report those elements or the analysis method. This is a practical reminder that design labels need accompanying operational and analytic descriptions.
Finally, the intervention is named inconsistently as alpha-2b in the title and summary and alfa-2a in the intervention and arm description. Such record-level discrepancies complicate precise interpretation of what was administered. The record does not resolve the inconsistency. Taken together, this study is statistically informative as an example of the limits of interpreting sparse registry results: the intended comparison is identifiable, but the primary effect, its precision, and important analytic details are not reported.
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 principal limitation for interpreting the study is that the registry record does not report an arm-level primary clinical-improvement result or a comparative estimate. The endpoint definition is available, but the counts, uncertainty, and test result are not. The record also indicates that the primary outcome has several categories or time points and is not reduced to one comparison.
Enrollment was 8, limiting the amount of information available for the comparison. The trial is marked terminated, but the reason is not reported in the registry record. The start is listed as 2013-01 and primary completion as 2017-06; these entries do not explain the termination or the completeness of follow-up.
Although the model is listed as crossover, the sequence, periods, treatment-switch timing, and any washout are not reported. The analysis method and the handling of potential period or carryover effects are also not reported. Masking is listed as none, but the registry record does not describe how clinical improvement was assessed or whether outcome assessment involved safeguards against bias.
The drug name differs across record entries: the title and summary refer to alpha-2b, while the intervention and arm description refer to alfa-2a. The record does not explain the discrepancy. It also does not report a sample-size justification, analysis populations, missing-data methods, multiplicity handling, or results for the secondary survival outcomes. These limitations constrain interpretation without establishing why any particular result or study decision occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pegylated Interferon Alpha-2b in Early Primary Myelofibrosis — NCT01758588.
- Registry record last updated 2018-07-24; status last verified 2018-06.
- Results first posted 2018-07-24.
- 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
NCT01758588 is a terminated, randomized, unmasked Phase II crossover study titled “Pegylated Interferon Alpha-2b in Early Primary Myelofibrosis.” Enrollment was 8. The registry describes an observation arm and a peginterferon arm, with the intervention listed as 50 micrograms once a week for up to 3 years. Drug naming differs across registry entries.
The primary endpoint is participant count for clinical improvement at one year, defined through blood-count or spleen-related criteria and a required response duration of no fewer than 8 weeks. Progression-free survival and overall survival are listed as secondary outcomes. The registry record does not report the primary arm-level comparison or secondary outcome results. It lists serious adverse events affecting 2 of 5 at risk in the treatment arm and 0 of 3 at risk in the observation arm; no deaths are reported.