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 Bovine Carotid Artery Biologic Graft and Expanded Polytetrafluoroethylene for Permanent Hemodialysis Access (NCT03300024), a randomized na study. The primary outcome is Percentage of Patients With Primary Graft Patency.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03300024 |
| Phase | NA |
| Condition | End Stage Renal Disease, Hemolysis, Arteriovenous Graft |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 10 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johns Hopkins University |
| Results posted | Yes |
2. Clinical Question
Population
People with end-stage renal disease requiring permanent hemodialysis access. The registry record lists an enrollment of 10, but does not report the number assigned to each arm or provide participant characteristics.
Intervention
A bovine carotid artery biologic graft. The record describes this as a biological fibrous matrix processed to enhance long-term patency and provide a flexible, compliant conduit.
Comparator
An expanded polytetrafluoroethylene graft, abbreviated ePTFE. The registry describes the comparator as a device graft, but does not report which specific graft each participant received.
Primary question
What percentage of patients in each group had primary graft patency one year after graft placement? Primary patency is defined as the interval from graft placement to any intervention for stenosis, with or without complete occlusion (thrombosis). The registry record says data were not collected for this outcome, so it cannot answer the comparison.
The study is described as a prospective randomized comparison for permanent hemodialysis access. The clinical question is whether the two graft approaches differ in the prespecified measure of primary patency, with additional listed outcomes concerning pseudoaneurysm formation and surgical-site infection. Those secondary outcomes do not supply a substitute for the primary comparison: no outcome analyses are listed, and the primary outcome has no collected data.
Random assignment can help make treatment groups comparable at the start of a study, on average, when implemented as planned. That general advantage does not itself establish that groups were formed as intended or that results can be estimated. The registry record does not report allocation details, group sizes, or results. Consequently, the posted record describes a research question and a planned comparison, not an answer about the relative outcomes of the grafts.
3. Trial Design
The registry describes a prospective, randomized, single-masked, parallel-group study. Its stated purpose was to compare bovine carotid artery (BCA) biologic grafts with expanded polytetrafluoroethylene (ePTFE) grafts for permanent hemodialysis access. Enrollment is listed as 10. The study status is terminated. The listed start date is 2015-02-01 and the primary completion date is 2018-02-12.
In a parallel-group design, participants are assigned to one of the intervention groups and outcomes are assessed in those groups. Randomization is intended, in general, to reduce systematic differences between groups at assignment. The registry labels the study randomized, but does not report the method used to generate the allocation sequence, how assignments were concealed, or how many participants entered each arm. The meaning of “single” masking—who was masked—is not reported in the registry record.
The ePTFE arm is described as using grafts selected by surgeons from several listed types; the record does not establish which type any participant received. The BCA arm is described as using a biological fibrous matrix conduit. These device descriptions define the interventions broadly, but the available record does not provide participant-level treatment information or details of graft placement.
The registry lists 24 outcome measures, including the primary patency measure and secondary measures concerning pseudoaneurysm formation and surgical-site infection. The same secondary outcome labels occur repeatedly in the record. Their distinct time points or categories are not established by those labels alone. No analyses are listed, and no primary outcome data were collected. Although enrollment is recorded as 10, the record does not establish how many participants were randomized, treated, followed, or included in any analysis. The reason for termination is 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 | Expanded Polytetrafluoroethylene (ePTFE) | Bovine Carotid Artery Graft |
|---|---|---|
| STARTED | 4 | 6 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 4 | 6 |
Reasons for not completing this period:
| Reason | Expanded Polytetrafluoroethylene (ePTFE) | Bovine Carotid Artery Graft |
|---|---|---|
| Physician Decision | 4 | 6 |
Analysis population for the primary outcome, as defined in the registry: Data was not collected for this outcome measure
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: Work on this project was discontinued. Baseline data for "Race and Ethnicity" was not collected.
| Characteristic | Unit | Expanded Polytetrafluoroethylene (ePTFE) | Bovine Carotid Artery Graft | Total |
|---|---|---|---|---|
| Participants analysed | 4 | 6 | 10 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 3 | 3 | 6 |
| Age, Categorical: >=65 years | Participants | 1 | 3 | 4 |
| Age, Continuous | years | 63.5 (60 to 70) | 67.2 (45 to 80) | 65.7 (45 to 80) |
| Sex: Female, Male: Female | Participants | 4 | 3 | 7 |
| Sex: Female, Male: Male | Participants | 0 | 3 | 3 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | Participants | 4 | 6 | 10 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Patients With Primary Graft Patency, measured over One year after Graft Placement.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of patients with primary graft patency, assessed one year after graft placement. The registry defines primary patency as the interval from placement until any intervention for stenosis, whether or not complete occlusion (thrombosis) occurs. This definition focuses on whether the graft remains free from an intervention prompted by stenosis during the stated period.
In general, a clearly defined endpoint helps translate a clinical question into an outcome that can be assessed consistently. Patency is relevant to a graft-access comparison because it describes how long an access remains usable without an intervention meeting the endpoint definition. The specified one-year assessment gives the outcome a time horizon. Interpretation would ordinarily depend on how the event was measured, how follow-up was handled, and how the groups were compared; those details are not reported in the registry record.
Most importantly, the record states that data were not collected for this outcome measure. It gives no percentage, event count, estimate of the difference between groups, or uncertainty interval. Therefore, the endpoint definition can be described, but the primary patency outcome cannot be estimated or compared from the posted results. The registry’s definition should not be confused with an observed finding: it specifies what the endpoint would measure, not what happened to participants.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a randomized comparison of BCA and ePTFE grafts, but it does not report outcome analyses. The primary outcome—percentage of patients with primary graft patency one year after graft placement—is explicitly marked as having no collected data. There is therefore no posted primary estimate for either group and no statistical comparison to interpret.
Enrollment is listed as 10, but that figure is not a substitute for an analyzed sample size. The record does not state how many participants were randomized, received a graft, completed follow-up, or contributed outcome information. It also gives no participant flow or group-specific baseline description. Without those details, the scope of any possible inference cannot be assessed.
There are no reported effect estimates, confidence intervals, or p-values, and the registry lists zero analyses. This means the record does not establish whether the groups differed, how large any difference might have been, or how precise an estimate would be. A confidence interval, in general, expresses the statistical uncertainty around an estimated effect under the assumptions of the analysis. No such interval is available for this primary comparison. A p-value, in general, summarizes how compatible observed data are with a specified null model; without a reported analysis and outcome data, there is no p-value to interpret.
The record lists pseudoaneurysm formation and surgical-site infection among secondary outcomes, with repeated entries for both labels. It does not provide corresponding outcome results or analyses. The adverse-event fields list 0 for serious events, other events, and deaths in each of the two groups. These entries are registry fields, but they do not supply participant-level event data, denominators, follow-up, or an analysis. They should not be read as a demonstrated absence of adverse events.
The study status is terminated. The reason for termination is not reported in the registry record. Termination alone does not explain why recruitment or follow-up ended, nor does it establish the direction or magnitude of any treatment effect. Likewise, the randomized designation describes the recorded design, not the completeness of execution or reporting.
The record includes assumptions for planning illustrations: two-sided significance level 0.05, equal allocation, a normal approximation, and an effect expressed as a fraction of the observed effect. These are not reported as the trial’s own sample-size justification or as its analysis plan. With no reported observed effect and no primary analysis, there is no result from which to interpret such an illustration. The posted record supports a description of the intended comparison and its reporting gaps, but not an efficacy or safety conclusion.
9. Statistical Methods Explained
The registry classifies the study as randomized, single-masked, and parallel-group. These terms describe design features, not the result. In a randomized study, an allocation process is intended to assign participants to groups in a way that reduces systematic selection differences. The details of sequence generation and allocation concealment are not reported in the registry record, so the implementation cannot be evaluated from this record.
In a parallel-group study, each participant is assigned to one group, and outcomes are compared across groups. The registry names ePTFE and BCA graft arms. It does not report the number assigned to each arm, the number who received the assigned graft, or the number followed to the primary endpoint. The total enrollment listed is 10, but the record does not provide an analysis population. In general, these counts matter because the number enrolled, randomized, treated, and analyzed may differ.
Single masking means that some party is intended not to know the assigned intervention, but the registry does not identify who was masked. In general, masking may limit the influence of knowledge of assignment on outcome assessment or participant reporting, depending on who is masked and how outcomes are measured. Without knowing the masked party or the procedures, the contribution of masking cannot be judged.
The primary endpoint is a percentage assessed one year after graft placement, with primary patency defined by the interval until an intervention for stenosis, with or without complete occlusion. The endpoint description identifies the event of interest and its time horizon. In general, a time-to-event analysis can use both the timing of an event and the duration of follow-up, and can accommodate participants whose event status is not known through the full follow-up period under specified assumptions. The registry does not report an analysis method, censoring rules, event counts, or follow-up completeness. No time-to-event estimate should therefore be inferred from the endpoint wording.
The record says primary outcome data were not collected and reports zero analyses. As a result, there is no sponsor analysis, adjusted estimate, unadjusted estimate, or uncertainty measure to interpret. A confidence interval is, in general, a range generated by a statistical procedure to represent uncertainty about an effect estimate. Its width depends on the information in the data and the method used; no interval is reported for this comparison. Statistical significance also cannot be assessed without an analysis and its assumptions.
The record’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation. They also describe the effect to detect as a stated fraction of the observed effect. These are generic inputs for planning illustrations and are not evidence of the study’s original design calculations. No trial-specific sample-size justification or analysis plan is reported in the registry record. Since the observed effect is not available, no planning illustration based on that effect can be given a trial-result interpretation. Such sample-size illustrations, when available, describe hypothetical planning requirements; they are not observed power and do not demonstrate that a study could detect an effect.
Over-dispersion is a general concern when observed variability exceeds what a chosen statistical model expects. If present, it can make standard errors and confidence intervals from an overly restrictive model unreliable. There is no outcome distribution or fitted model in this record from which to assess over-dispersion, and no reported model choice to evaluate. The same limitation applies to other modeling assumptions: without observations and analysis details, their adequacy cannot be checked.
The registry lists 24 outcome measures, including repeated labels for pseudoaneurysm formation and surgical-site infection. Multiple outcomes can create a multiplicity issue in general: evaluating many hypotheses may increase the chance of at least one apparently unusual result if each is assessed separately. Researchers may address this through prespecification, adjustment, or a clear hierarchy of outcomes. Such procedures are not reported in the registry record. The repeated labels do not establish distinct tests, time points, or categories, so the number of inferential comparisons cannot be determined from the labels alone.
The adverse-event record lists zero serious events, other events, and deaths in each group. These entries do not provide the denominators, exposure time, ascertainment method, or analysis needed for comparative safety inference. A zero in a registry field is not equivalent to a demonstrated zero risk. For rare events in particular, general statistical interpretation depends on the amount and completeness of observation, information not reported.
Overall, the listed design features and endpoint definition explain what the study set out to compare. They do not provide the data or analytic detail required to estimate a treatment contrast, quantify its precision, assess statistical assumptions, or evaluate whether the intended methods were implemented.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 24 outcome measures. Among the named secondary outcomes are pseudoaneurysm formation at the access site and surgical-site infection, each appearing repeatedly. The primary endpoint is one-year primary graft patency. The repeated secondary labels do not clarify whether they refer to separate time points, categories, or duplicated entries, so the number of distinct planned comparisons is not clear from the record.
Multiplicity is a general statistical concern when several outcomes or hypotheses are tested. If each test is treated as a separate opportunity to find a result, the chance of at least one apparently significant finding can increase. Common approaches include prioritizing a primary outcome, specifying a testing hierarchy, or adjusting inference across a defined family of tests. The registry record does not report a multiplicity strategy, a hierarchy beyond naming the primary endpoint, or a statistical analysis plan. It lists no analyses, so no adjustment or unadjusted secondary results are available to assess.
The record explicitly states that primary outcome data were not collected. It does not report missingness by group, reasons for missing data, follow-up completion, or procedures for handling missing outcomes. It is therefore not possible to distinguish an outcome that was never collected from outcomes missing for some participants after collection, or to assess whether missingness could bias an estimate.
Analysis populations are also not reported. There is no count identifying participants randomized, treated, followed, or included in an analysis, and no description of an intention-to-treat or other population. Enrollment of 10 alone cannot establish any of those counts. These gaps prevent evaluation of attrition, denominator choice, or whether analyses followed the recorded randomization. No statistical conclusion about the primary or secondary outcomes can be drawn from the available record.
11. What the Result Does, and Does Not, Mean
The registry record means that a prospective randomized comparison of BCA and ePTFE grafts was registered for permanent hemodialysis access, with primary patency specified as the main outcome. It also records an enrollment of 10 and a terminated study status. These registry entries describe the study’s recorded design and status; they do not establish an outcome difference.
The record does not show whether one graft had better or worse primary patency. It reports no primary outcome data, no analyses, and no group-specific estimates. It also provides no confidence interval or p-value. Thus neither the direction nor the size nor the precision of a possible effect can be determined. The absence of a reported analysis is not evidence that the treatments had identical outcomes.
The repeated secondary outcome labels do not provide findings about pseudoaneurysms or surgical-site infections. Similarly, the adverse-event fields listing zero counts do not establish that no adverse events occurred or that the groups had equivalent safety. The record does not provide the details needed to interpret those entries as participant-level incidence results.
In general, an inconclusive or unavailable result differs from evidence supporting no effect. To assess whether a difference is small enough to be clinically unimportant, an analysis would need an estimate and sufficiently precise uncertainty bounds, interpreted against an appropriate clinical margin. Neither an estimate nor such a margin is reported in the registry record. The stated endpoint and design cannot replace those data.
The terminated status does not explain why the study ended, and the record does not report whether termination was related to enrollment, conduct, data availability, or another cause. No reason should be inferred from status alone. The appropriate interpretation is limited: the registry records an intended comparison, but its posted results do not answer the primary question or support a comparative conclusion about patency, secondary outcomes, or adverse events.
12. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the distinction between a prespecified question and an estimable result. The registry defines a primary patency outcome and names two graft approaches, but states that primary outcome data were not collected. A well-defined endpoint is necessary for a useful comparison, yet definition alone cannot produce an effect estimate or quantify uncertainty.
It also highlights why enrollment and analysis counts should not be treated as interchangeable. The record lists enrollment of 10, but does not report group sizes, follow-up, or analysis populations. In general, transparent accounting of participants at each stage allows readers to judge how much information supports an estimate and whether loss to follow-up might affect interpretation. Those details are not available in this record.
The study’s randomized designation is informative about the intended design, but statistical interpretation also depends on the conduct and reporting of allocation, outcome assessment, and analysis. The registry does not report those operational details or a statistical analysis plan. This limits assessment of the reliability of any hypothetical comparison, independent of the absence of outcome data.
Finally, the record lists multiple outcomes and repeated secondary labels without reporting a multiplicity approach or analyses. This underscores the value of clearly distinguishing primary and secondary questions and documenting how multiple comparisons will be handled. Here, the primary outcome itself cannot be estimated, so the broader lesson is about the limits of inference when registered questions are not accompanied by collected outcomes and analysis results—not about which graft performs better.
13. 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 central limitation is that the registry explicitly says data were not collected for the primary endpoint. No primary patency result is available at the one-year time point, despite a definition of the endpoint. There are no reported outcome analyses, estimates, confidence intervals, or p-values. This prevents both a comparative assessment and an evaluation of precision.
The recorded enrollment is 10, but the registry does not report group allocation counts, the number receiving each graft, follow-up completion, or analysis denominators. Participant characteristics are not reported in the available record. These omissions mean that the effective information available for any comparison cannot be established from enrollment alone.
The study is marked terminated, but the reason for termination is not reported in the registry record. The record also does not explain whether the listed completion date represents complete follow-up for all enrolled participants. No conclusions about the circumstances or consequences of termination can be drawn.
Methodological details are limited. The record does not identify who was masked, describe the randomization procedure, or report an analysis plan. It does not specify how missing outcomes would be handled, describe an analysis population, or state how the repeated secondary outcome labels correspond to distinct time points or categories. A multiplicity strategy is not reported.
The adverse-event fields list zero serious events, other events, and deaths in both groups, but do not provide event definitions, denominators, follow-up, or an analysis. These entries cannot support a comparative safety estimate. Taken together, the record supports description of the trial design and its stated aims, but not conclusions about patency, secondary outcomes, or adverse events.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Bovine Carotid Artery Biologic Graft and Expanded Polytetrafluoroethylene for Permanent Hemodialysis Access — NCT03300024.
- Registry record last updated 2019-05-21; status last verified 2019-05.
- Results first posted 2019-05-14.
- 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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17. Record Summary
NCT03300024 is a prospective randomized, single-masked, parallel-group study comparing BCA biologic grafts with ePTFE grafts for permanent hemodialysis access. Enrollment is listed as 10, and the study status is terminated. The primary endpoint is the percentage of patients with primary graft patency one year after placement, defined by the interval until intervention for stenosis, with or without complete occlusion.
The registry states that primary outcome data were not collected and lists zero analyses. It names secondary outcomes concerning pseudoaneurysm formation and surgical-site infection, but does not report their results. The adverse-event fields contain zero entries for serious events, other events, and deaths in each group; these do not provide a comparative safety analysis. The reason for termination, analysis populations, group sizes, and statistical analysis plan are not reported in the registry record. Accordingly, the record describes the intended comparison but does not provide evidence to estimate comparative outcomes.