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 Use Of Fragmin In Hemodialysis (NCT01879618), a na phase 3 study. The primary outcome is Mean Percent of Successful HD Sessions.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01879618 |
| Phase | Phase 3 |
| Condition | Chronic Renal Failure |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 152 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Participants with chronic renal insufficiency receiving hemodialysis were studied. The registry record describes the condition as chronic renal failure and states that the primary efficacy analysis included participants who received at least one dose of study medication.
Intervention
Fragmin, or dalteparin sodium, was given according to a flexible dosing regimen outlined in the protocol. The study aimed to assess dose adjustment in relation to clinical needs during dialysis.
Comparator
There was no comparison group. The registry describes a single-group study, with allocation recorded as not applicable. The results therefore do not provide a like-for-like control comparison.
Primary question
The main question was what mean percentage of hemodialysis sessions met the study definition of success during the stated assessment period of 20 sessions, up to 4 hours. Success was based on completion as planned without specified clotting-related problems. The numerical estimate and its confidence interval are not reported in the registry record.
3. Trial Design
This was a Phase IIIb, open-label, single-group study of Fragmin during hemodialysis. The registry records an enrollment of 152 and lists Pfizer as the sponsor. It gives the study status as completed. There was no random allocation and no masking; allocation is recorded as not applicable, and masking as none. These features matter because the study was not designed as a randomized comparison between Fragmin and a control treatment.
The intervention was Fragmin given under a flexible dosing regimen described in the protocol. The registry’s stated aim was to determine whether the dose could be adjusted to suit participants’ clinical needs during dialysis. The primary outcome was the mean percentage of successful hemodialysis sessions over 20 sessions, with each session lasting up to 4 hours. A secondary outcome was the mean percentage of sessions with an acceptable dose.
The efficacy analysis used the Full Analysis Set, defined in the record as participants who received at least one dose of study medication. The primary analysis included 2776 hemodialysis sessions from 151 participants. Sessions are repeated observations within participants, rather than independent observations from separate people; the analysis therefore used a method intended to account for clustering. The registry record does not report numerical results for either outcome, nor does it list analysis entries.
The design can describe outcomes observed under the study regimen, but without a comparator it cannot establish how those outcomes would differ under another regimen or no treatment. Open-label conduct also means treatment was not masked. Further details about procedures intended to reduce bias 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.
Before assignment: The Screening Visit was performed within 9 days preceding first HD session where FRAGMIN was administered. The Final Study Visit took place 5 to 15 days after the final study HD session where the participant was treated with Fragmin (# 20 or the last HD session that was completed, if the partcipant prematurely terminated).
Overall Study
| Stage | FRAGMIN |
|---|---|
| STARTED | 152 |
| COMPLETED | 131 |
| NOT COMPLETED | 21 |
Reasons for not completing this period:
| Reason | FRAGMIN |
|---|---|
| Does not meet entrance criteria | 1 |
| Withdrawal by Subject | 1 |
| Surgery;changed schedule; not available | 8 |
| Protocol Violation | 6 |
| Adverse Event | 5 |
Analysis population for the primary outcome, as defined in the registry: The Full Analysis Set (FAS) was used for all efficacy analyses which included all participants who received at least one dose of study medication. There were 2776 HD sessions from 151 participants included in the primary analysis.
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: The Safety Analysis Set consisted of all participants who received at least one dose of study medication.
| Characteristic | Unit | FRAGMIN |
|---|---|---|
| Participants analysed | 152 | |
| Age, Continuous | Years | 57.1 (SD 14.7) |
| Sex: Female, Male: Female | Participants | 46 |
| Sex: Female, Male: Male | Participants | 106 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Percent of Successful HD Sessions, measured over 20 HD sessions (up to 4 hours).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Percentage of HD Sessions |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the mean percentage of hemodialysis sessions classified as successful. The registry defines a successful session by whether it was completed as planned without premature termination due to Grade 3 or 4 clotting or a saline flush intended to prevent loss of the extracorporeal circuit because of clotting. The definition also describes circumstances in which the participant’s blood could not be returned or the exact extent of clotting could not be assessed. Sessions ending early for Grade 1 or 2 clotting, a safety event, machine failure, or access-site displacement were excluded from the analysis.
This endpoint focuses on session-level performance of the extracorporeal system during dialysis, rather than on a participant-level clinical outcome. A percentage expresses the frequency of sessions meeting the study’s criteria relative to the sessions included under its analysis rules. Repeated sessions from the same participant may be correlated, so treating every session as statistically independent could make uncertainty appear too small. The registry says the point estimate and confidence interval were computed with a generalized estimating equation model for clustered binomial data.
The registry record gives the endpoint definition and assessment period but does not report the numerical mean or its 95% confidence interval. The observed level of success and the precision of its estimate therefore cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a clinically focused process outcome: the mean percentage of hemodialysis sessions meeting the study’s definition of success. It also specifies how sessions were classified and states that the primary analysis accounted for clustering of sessions within participants. These details clarify what the endpoint was intended to measure and how repeated observations were handled.
However, the numerical primary result is not reported in the registry record. Neither the point estimate nor its 95% confidence interval is available in the record. As a result, the observed proportion of successful sessions and the precision of that estimate cannot be described. The same limitation applies to the secondary outcome, the mean percentage of sessions with an acceptable dose: its title is listed, but its numerical result is not reported in the registry record.
The design also limits the kind of interpretation possible. This was a single-group, open-label study with no control arm. Its results, if reported, would describe outcomes under the flexible Fragmin regimen in the study population. They would not by themselves estimate a treatment contrast against another dose or treatment, and they would not separate the regimen’s effects from other explanations for the observed outcomes. The registry explicitly notes that this is not a randomized comparison and that the arms are not a like-for-like control comparison.
The primary analysis included 2776 hemodialysis sessions from 151 participants. Those sessions are clustered observations: sessions from one person may share characteristics and are not necessarily independent. The stated use of a generalized estimating equation model is relevant because it accounts for that clustered structure when estimating the endpoint and confidence interval. This modeling choice does not fill the gap in the reported result; without the estimate and interval, neither the outcome level nor the uncertainty can be judged.
Enrollment was 152, while the primary efficacy analysis population comprised 151 participants who had received at least one dose. The registry does not explain the difference between the enrollment figure and the primary analysis population. It also does not report detailed missing-data handling, sensitivity analyses, interim analyses, or a statistical analysis plan. Conclusions about how these issues were addressed would therefore go beyond the registry record.
Any planning calculations based on an observed effect should be read as illustrations, not as the trial’s original design rationale or as observed power. The stated calculation assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Since this study had no randomized comparator and the registry record does not report its numerical primary result, those assumptions do not turn this single-group study into a comparative trial. They also cannot substitute for a reported outcome estimate and confidence interval.
9. Statistical Methods Explained
Why account for repeated sessions?
Each participant could contribute repeated hemodialysis sessions, so the session-level observations may be related within a participant. For example, a participant’s clinical characteristics or access conditions can persist across sessions. General statistical principle: when observations within a person are correlated, an analysis that treats all observations as independent can misstate the uncertainty around an estimate. The registry reports that the primary point estimate and 95% confidence interval were computed using a generalized estimating equation model for clustered binomial data.
A generalized estimating equation, or GEE, is a population-averaged approach for estimating relationships when measurements are clustered, such as repeated observations within a participant. In this study, the endpoint was based on whether a session met a success definition, making a binomial framework relevant. The clustering adjustment addresses the fact that sessions from the same participant may be more alike than sessions from different participants. This is a general explanation of the method; the registry record does not report the working correlation structure, variance estimator, or further model specification.
What does the mean percentage describe?
The primary outcome is titled Mean Percent of Successful HD Sessions and has a unit of percentage of HD sessions. It summarizes session-level success under the study’s specified criteria, rather than reporting a separate result for every participant. The registry also identifies the outcome parameter as a mean. General statistical principle: a mean percentage provides a compact summary of the frequency of a binary event across the analyzed observations, subject to the exact definition of the analysis population and denominator. The registry’s session exclusions are therefore important to interpreting the measure.
Sessions were excluded if they ended prematurely due to Grade 1 or 2 clotting, a safety event, machine failure, or access-site displacement. The definition also identifies clotting-related circumstances that count against success. The record does not report a numerical denominator for the primary endpoint or a breakdown of excluded sessions. It is consequently not possible to reconstruct the endpoint from the registry record, and no new percentage can be calculated from the information recorded.
How should a confidence interval be read?
The registry says the primary estimate was accompanied by a 95% confidence interval, but neither the estimate nor interval limits are reported in the registry record. General statistical explanation: a confidence interval conveys uncertainty around an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, all else equal; it does not establish that an outcome is clinically important, nor does it remove design limitations. Because the interval itself is absent, the precision of this study’s primary estimate cannot be evaluated.
Confidence intervals also depend on the analysis model and data structure. Here, the stated GEE approach is intended to reflect clustering of session observations within participants. The interval should therefore be understood as arising from that clustered analysis rather than from a calculation that assumes every session is independent. Details beyond the stated method are not reported in the registry record.
What can a single-group design estimate?
A single-group study can describe outcomes observed among participants receiving the study regimen. It does not supply a concurrent control group for estimating a between-group treatment effect. General statistical principle: without a control comparison, changes or outcomes cannot be attributed uniquely to the intervention, because other factors may also contribute. In this record, there is no randomized comparator, and the registry cautions against treating the arms as a like-for-like control comparison.
The study was open-label, so masking was not used. The registry record does not report methods for limiting potential bias associated with open-label conduct. Outcome definitions and analysis methods can improve clarity, but they do not create a control comparison or eliminate every source of bias.
How do planning illustrations differ from observed results?
Planning calculations based on an observed effect are not the same as the trial’s observed outcome and are not observed power. The record’s stated assumptions for such calculations include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. These are planning assumptions, not evidence that this single-group trial used a two-arm randomized design. The registry does not report the trial’s sample-size justification, and the numerical primary effect is not reported in the registry record.
In general, a planning illustration asks what sample size might be needed under specified assumptions and a chosen effect to detect. Its answer depends on those assumptions and should not be read as a property of the completed trial. The available record does not establish that the trial was designed using the stated illustration assumptions. Nor do those illustrations replace the missing primary estimate, confidence interval, or a comparative analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures: the primary mean percentage of successful hemodialysis sessions and the secondary mean percentage of sessions with an acceptable dose. It reports no analysis entries. Numerical results for these outcomes are not reported in the registry record. The record does not specify how multiplicity across outcomes was addressed, whether any outcome hierarchy beyond the primary and secondary labels governed interpretation, or whether any interim analyses were conducted. Those details are not reported in the registry record.
The efficacy population is described as the Full Analysis Set, comprising participants who received at least one dose of study medication. The primary analysis included 2776 hemodialysis sessions from 151 participants. Enrollment was 152. The registry does not explain why the primary analysis population differs from enrollment, and the exact contribution of each participant or the number of sessions excluded from the endpoint analysis is not reported in the registry record.
The outcome definition excludes sessions ending prematurely for specified reasons. The record does not describe a broader missing-data strategy, how incomplete session data were handled, or whether sensitivity analyses examined alternative assumptions. It also does not provide a statistical analysis plan or sample-size justification. These omissions limit assessment of whether all planned analyses and missing-data decisions can be followed from the record. They do not establish that particular procedures were or were not used; those details are simply not reported in 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 |
|---|---|---|---|
| FRAGMIN | 3 | 152 | 2.0% |
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 |
|---|---|
| FRAGMIN | 27 of 152 |
Most frequent serious adverse event terms
| Event term | Organ system | FRAGMIN |
|---|---|---|
| Atrial fibrillation | Cardiac disorders | 1 of 152 |
| Pneumonia | Infections and infestations | 1 of 152 |
| Influenza | Infections and infestations | 1 of 152 |
Most frequent non-serious adverse event terms
| Event term | Organ system | FRAGMIN |
|---|---|---|
| Arteriovenous fistula site haemorrhage | Injury, poisoning and procedural complications | 19 of 152 |
| Hypotension | Vascular disorders | 8 of 152 |
Serious events with the highest arm-level rate: atrial fibrillation (0.7%), pneumonia (0.7%), influenza (0.7%).
The registry records 3 under serious adverse events among 152 at risk, and 27 under other adverse events among 152 at risk. These figures are counts as recorded in the safety summary; they are not the primary efficacy endpoint and should be read separately from the hemodialysis-session outcome. The registry lists atrial fibrillation, pneumonia, and influenza among the top serious adverse event terms, each at 0.7%.
The record does not report deaths in the safety summary. A missing death value should not be interpreted as a confirmed absence of deaths; deaths are not reported in the registry record. The registry information also does not establish whether an event was caused by Fragmin. General statistical principle: adverse-event counts describe events recorded during a study, while causal attribution requires additional clinical and methodological assessment. In a single-group study, there is no control group for comparing event frequencies under another regimen.
The safety counts do not provide detail about event timing, duration, severity beyond the serious-event classification, recurrence, or individual-level overlap. Those details are not reported in the registry record. The listed percentages and counts should therefore be read as the safety information recorded, not as a complete characterization of risk.
12. What the Result Does, and Does Not, Mean
The registry record documents a study of flexible-dose Fragmin during hemodialysis and defines a session-level primary outcome based on successful completion under specified clotting-related criteria. It also states that repeated sessions were analyzed with a method intended to account for clustering within participants. These features describe what the investigators set out to measure and how the primary estimate was intended to be calculated.
The primary numerical estimate and its 95% confidence interval are not reported in the registry record. The secondary outcome’s numerical result is also not reported. Therefore, the registry record does not permit a reader to determine the observed mean percentage of successful sessions, the precision of that estimate, or the observed percentage of sessions with an acceptable dose. No conclusion about the level of either outcome can be drawn from the definitions alone.
The study’s single-group design is another boundary on interpretation. The record describes outcomes under the flexible regimen, but it includes no control comparison. As a result, it cannot show how those outcomes compare with another treatment or dosing strategy, or isolate the contribution of Fragmin from other influences. Open-label conduct adds a further design consideration because treatment was not masked.
The primary efficacy population included 151 participants, and the analysis used 2776 sessions. These figures describe the analysis recorded, not evidence of a treatment effect. The safety summary separately records serious and other adverse-event counts, but does not establish causal relationships. Overall, the registry supports a description of the study question, endpoint definition, analysis approach, and selected safety figures; it does not provide the numerical efficacy results needed to characterize the primary outcome.
13. Why This Trial Matters Statistically
This study raises statistical issues that commonly arise when clinical outcomes are measured repeatedly within individuals. Hemodialysis sessions are session-level observations, but multiple sessions from the same participant may be correlated. Recognizing that structure matters because uncertainty estimates should reflect the data’s clustering rather than treating every session as an independent observation. The registry’s use of GEE for clustered binomial data explicitly addresses this feature of the design.
The endpoint definition also illustrates why operational rules matter. Success depends on specified clotting-related events, while sessions ending for several other reasons are excluded. These choices shape the outcome being estimated and determine which observations contribute to it. A clear endpoint definition is essential to interpreting a percentage, but a definition alone is not a result. In this case, the primary estimate and confidence interval are not reported in the registry record.
The single-group, open-label design further illustrates the distinction between describing an outcome and estimating a comparative effect. A study can characterize what was observed under a regimen without showing how that outcome differs from a concurrent control. For clinical researchers, this is a reminder to match the interpretation to the design and to avoid reading a single-group outcome as a controlled treatment contrast.
Finally, the record shows why reporting completeness is part of statistical interpretation. Outcome titles, populations, methods, and safety counts are useful, but they cannot replace numerical efficacy estimates, uncertainty intervals, and transparent accounts of missing-data and multiplicity decisions. Where those details are absent, the appropriate conclusion is limited to what the registry record actually reports.
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 most important limitation for interpreting efficacy is that the registry record does not report the numerical primary outcome or its 95% confidence interval. The secondary outcome is listed without a numerical result as well. Without these values, the observed outcome level and its precision cannot be assessed.
The study had a single-group, open-label design, with no randomized control arm. It can describe outcomes under the flexible Fragmin regimen but cannot provide a like-for-like comparison with another treatment or dosing strategy. The record does not report procedures intended to address potential bias associated with open-label conduct.
The primary endpoint excludes sessions that ended prematurely for specified reasons, including Grade 1 or 2 clotting, safety events, machine failure, or access-site displacement. The registry does not report counts for these exclusions, a detailed endpoint denominator, or how incomplete data were handled. The analysis population comprised 151 participants, while enrollment was 152; the reason for that difference is not reported in the registry record.
Further limitations include the absence of reported analysis entries, a statistical analysis plan, a sample-size justification, and details about multiplicity, interim analyses, or sensitivity analyses. The registry also provides only limited safety detail and does not report deaths. These omissions restrict assessment of analytic decisions and the completeness of outcome reporting; they should not be treated as proof that particular methods or events were absent.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Use Of Fragmin In Hemodialysis — NCT01879618.
- Registry record last updated 2017-03-10; status last verified 2017-01.
- Results first posted 2016-12-29.
- 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.
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18. Record Summary
The registry describes a completed Phase IIIb, open-label, single-group study of flexible-dose Fragmin during hemodialysis, sponsored by Pfizer. Enrollment was 152. The primary outcome was the mean percentage of successful hemodialysis sessions over 20 sessions, up to 4 hours. Its definition focused on completion as planned without specified clotting-related problems, and the analysis used GEE for clustered binomial data.
The Full Analysis Set included participants who received at least one dose. The primary analysis included 2776 sessions from 151 participants. The registry lists a secondary outcome concerning the mean percentage of sessions with an acceptable dose. Numerical results for the primary and secondary outcomes are not reported in the registry record. The safety summary records 3 serious adverse events and 27 other adverse events among 152 at risk, with three serious-event terms listed at 0.7% each.