Outcomes for One-stage and Two-stage Brachial Basilic Arteriovenous Fistulas: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Outcomes for One-stage and Two-stage Brachial Basilic Arteriovenous Fistulas (NCT04376567), a randomized na study. The primary outcome is Number of Participants Who Had Successful Use of Arteriovenous Fistula for Dialysis.

2. Clinical Question

The central comparison concerns the timing and staging of the procedure, not whether an arteriovenous fistula is created. The registry describes both approaches as standard care and states that the study aimed to compare patient-centered outcomes and quality of life. It also says the choice between the approaches is left to the surgeon because clear data on the best method are lacking.

In the posted primary results, one participant in the one-stage arm and one participant in the two-stage arm are recorded as having successful fistula use. With one participant reported in each arm, those counts cannot establish how the approaches compare in a broader patient population. The record does not report an estimable statistical comparison.

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. The two groups were assigned to one-stage or two-stage BBAVF procedures. The study is classified as phase NA. The registry lists an enrollment of 2 and reports one participant in each arm.

In the one-stage approach, the arteriovenous anastomosis and basilic vein transposition occur during the same procedure. In the two-stage approach, the anastomosis is created at the first procedure; superficialization or transposition is carried out 6 to 8 weeks later, after maturation. The listed intervention is the one-stage procedure, while descriptions of both arms appear in the registry.

The trial start date is 2021-10-01, and the primary completion date is 2023-11-01. Its status is terminated. The reason for termination and the circumstances surrounding it are not reported in the registry record. The registry does not report a planned or actual sample-size justification, recruitment details, or the number of people screened or excluded.

The primary outcome is successful use of the fistula for dialysis within 6 months. The registry also lists three secondary outcomes: catheter-related complications, catheter dependency lasting more than 3 months after fistula creation, and Patient-Reported Outcomes Measurement Information System scores over 6 months. Details such as the specific score domains, planned measurement schedule, and analysis procedures are not reported in the registry record.

Randomization is intended to make treatment groups comparable on average, but that protection depends on adequate information and cannot be evaluated from a very small set of reported outcomes. No masking means participants and care providers were not masked to the assigned procedure. Whether outcome assessors were masked 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

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Who Had Successful Use of Arteriovenous Fistula for Dialysis, measured over 6 months.

The primary endpoint counts participants who successfully used their BBAVF for dialysis within 6 months of surgical creation. The registry defines functional clinical patency as using two dialysis needles in at least 75% of dialysis sessions over four weeks, without an additional procedure or surgery. Providers determine whether the definition has been met.

This endpoint addresses whether the fistula is usable for its intended dialysis purpose, rather than simply whether the procedure was performed or the fistula was created. A measure tied to actual dialysis use can therefore represent a clinically relevant functional outcome. It is also a binary participant-level outcome in this record: a participant either meets the registry definition or does not.

Interpretation depends on applying the definition consistently, including the observation period, dialysis-session threshold, and rule concerning additional procedures or surgery. Provider determination may involve clinical judgment; details about adjudication, assessor training, or independent review are not reported in the registry record.

The posted result records one successful-use outcome in each arm. The registry does not provide a two-arm estimate or uncertainty interval for this endpoint. With the reported arm sizes, the counts offer very limited information about how often successful use might occur among a larger group, or whether the approaches differ.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General statistical context: A randomized parallel-group design assigns participants to one of the procedures and compares outcomes between the resulting groups. Randomization can reduce systematic differences in baseline characteristics across groups over repeated applications of a trial, but it cannot guarantee balance in a particular small trial. With one participant reported in each arm, chance variation in participant characteristics can have a substantial influence on the observed outcomes.

The registry describes the trial as randomized and unmasked. It does not report the randomization sequence method, allocation concealment procedures, or masking of outcome assessors. These details matter because predictable assignment can affect who enters each group, while awareness of treatment assignment can influence care, reporting, or outcome assessment. The registry record does not give enough information to evaluate those processes.

General statistical context: A binary endpoint classifies each participant into one of two outcome states. The primary endpoint is defined as successful use or not meeting the success definition within 6 months. Analysis of a binary outcome ordinarily compares event counts or event probabilities between groups, with an estimate of uncertainty. The registry’s stated reason for skipping the two-arm comparison is that values are missing or not estimable for this binary endpoint. Thus, there is no comparative effect estimate to explain or interpret.

A confidence interval, when an estimate is available, gives a range of values compatible with the data and analysis assumptions. Its width reflects precision: sparse data generally yield limited precision. A p-value, when reported, assesses how incompatible the data are with a specified null model under the analysis assumptions; it does not measure the size or clinical importance of an effect. Neither a confidence interval nor a p-value for the primary two-arm contrast is reported in the registry results.

The primary endpoint includes provider determination and a specified pattern of dialysis use: two needles in at least 75% of dialysis sessions over four weeks, with no additional procedure or surgery. Consistency in applying this definition is important for comparability. The registry does not report whether an independent adjudication process was used, how borderline cases were handled, or how the required dialysis records were collected.

The registry lists three secondary outcomes alongside the primary endpoint. Multiple outcomes can raise multiplicity concerns when several statistical tests are conducted, because repeated testing can increase the chance of at least one apparently notable finding by chance. General statistical context: Trials may address this by specifying a hierarchy, adjustment method, or exploratory status in advance. The analysis plan, any multiplicity procedure, and results for the secondary outcomes are not reported in the registry record, so no adjustment or outcome hierarchy can be described.

The registry states that sample-size planning illustrations use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. It also distinguishes participants per arm for most outcomes from total events for time-to-event outcomes. These are planning assumptions, not a report of the trial’s design rationale or an observed-power calculation. The record does not report the trial’s own sample-size justification. With the posted primary result not estimable as a two-arm comparison, planning values based on that observed effect cannot provide a dependable basis for interpreting the result.

Over-dispersion is a general concern when outcome variability exceeds what a statistical model assumes. It can make standard errors too small if ignored. The primary endpoint is a participant count for a binary outcome, and no fitted model or dispersion estimate is reported. Therefore, over-dispersion is not a reported feature of this analysis and should not be invoked as an explanation for the unavailable comparison.

The registry does not report whether the analysis was intention-to-treat, per-protocol, or based on another population. It also does not describe missing-data methods, protocol deviations, or sensitivity analyses. These are important because exclusions or missing outcome observations can affect a randomized comparison, particularly when the amount of information is already limited. No claim about the handling of these issues can be made from the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("One Stage Approach", "Two Stage Approach")
n      <- c(1, 1)
events <- c(1, 1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  One Stage Approach  1  1  100.0  2.5  100.0  20.7  100.0  15.8  98.7
ARM  Two Stage Approach  1  1  100.0  2.5  100.0  20.7  100.0  15.8  98.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and three secondary outcomes. It does not report a statistical analysis plan, a hierarchy among the outcomes, or a multiplicity adjustment. When a study tests several outcomes, the chance of a false-positive finding can increase if each is assessed independently. General statistical context: Prespecified outcome priorities and an appropriate adjustment or interpretation strategy can help readers distinguish confirmatory findings from exploratory ones. No such strategy is reported in the registry record.

Results for the listed secondary outcomes are not included in the posted outcome data. The record therefore does not support conclusions about catheter-related complications, catheter dependency lasting more than 3 months, or patient-reported scores over 6 months. The registry lists four outcome measures in all, but details about the fourth measure beyond the primary outcome and listed secondary outcomes are not reported in the registry record.

Missing-data handling is not reported in the registry record. There is no account of whether any outcome data were missing, how missing observations were classified, or whether an imputation or sensitivity method was used. The registry reports one participant in each arm and one successful-use outcome in each arm, but does not describe an analysis population or provide participant flow information. These counts alone cannot establish whether there were missing assessments or exclusions at other stages.

Analysis populations are also not reported in the registry record. Without knowing whether the reported results include all randomized participants or another defined group, the relationship between assignment and analyzed outcomes cannot be assessed in detail. The absent analysis plan and secondary results limit assessment of selective reporting as well as multiplicity.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry’s adverse-event figures list one participant at risk in each arm. In each arm, the serious adverse-event count is 0, the other adverse-event count is 0, and the death count is 0. These are the posted counts for the reported groups; they should be read as descriptive figures, not as precise estimates of safety.

General statistical context: An observed count of zero does not show that an event cannot occur. When the number of people observed is very small, uncommon events may not appear even if they are possible. A meaningful comparison of event rates also requires adequate follow-up and clear information about event definitions, collection, and completeness.

The registry does not list any top serious adverse-event terms. It does not report event-specific definitions, severity grading procedures, follow-up duration for safety, or whether events were considered related to a procedure. The primary outcome’s 6-month timeframe should not be assumed to be the safety follow-up period, which is not reported in the registry record.

These figures do not establish that either procedure is safer. They record no serious adverse events, other adverse events, or deaths in the reported participants, while offering little information about the range or frequency of possible harms in a larger population.

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

The posted primary outcome counts show successful fistula use for the one participant reported in each arm. That is a descriptive account of the recorded participants, not a reliable estimate of success rates across patients who might undergo either procedure. The registry does not provide an estimable two-arm comparison for the binary endpoint.

The result does not establish that one-stage and two-stage procedures are equivalent. It also does not show that one approach is better or worse. Equal observed counts in very small groups can occur across a wide range of underlying outcomes; without a comparative estimate and its uncertainty, the data cannot distinguish among those possibilities.

Nor do the counts answer every question raised by the trial’s stated aims. The registry describes an interest in patient-centered outcomes and quality of life, and it lists patient-reported scores as a secondary outcome. Results for that measure are not reported. The primary endpoint focuses on whether the fistula met a defined use threshold, which is relevant to function but does not by itself describe all aspects of patient experience.

The safety counts are also descriptive. The record lists no serious adverse events, other adverse events, or deaths in the reported participants, but the reported group sizes are too limited to characterize uncommon harms or compare safety. The reason for trial termination is not reported in the registry record, so the termination status should not be interpreted as evidence about either procedure’s outcomes.

The appropriate statistical reading is therefore narrow: successful use was recorded for the reported participant in each arm, while a comparative effect and its precision are unavailable. The findings are insufficient to establish equivalence, superiority, or a safety difference. They should be understood as limited registry results from a terminated pilot trial rather than a conclusive comparison.

14. Why This Trial Matters Statistically

This trial addresses a practical procedural choice: whether BBAVF creation should be completed in one procedure or staged, with transposition or superficialization after an interval. The registry states that both approaches are standard care and that clear data on the best method are lacking. Comparing outcomes through random assignment is a relevant way to investigate that question, and the stated focus on patient-centered outcomes extends beyond technical procedure details.

The statistical importance of the record lies partly in showing the difference between a trial question and an answerable comparison. The study asks a comparative question, but the posted primary results contain one participant in each arm and the registry identifies the binary comparison as not estimable. A randomized design does not by itself guarantee that the resulting data will be sufficiently informative to quantify an effect.

This distinction matters for readers interpreting equal counts. The two observed successful-use counts are not evidence of equivalence, and an unavailable comparison is not a finding of no difference. Precision and the amount of information matter alongside the direction of observed results. Here, the record does not include a comparative estimate or uncertainty interval.

The case also illustrates why outcomes beyond the primary endpoint matter for patient-centered questions. Catheter complications, duration of catheter dependency, and patient-reported scores are listed, but their results are not reported in the registry record. Without those results, the broader aims described in the study summary cannot be assessed from the posted outcomes.

Finally, the terminated status and absence of a reported statistical analysis plan constrain interpretation. Those limitations do not invalidate the recorded counts, but they define what can be learned from them: a small descriptive record, not a resolved comparison of the procedures.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation is the very limited amount of outcome information: the registry reports one participant in each arm. The primary endpoint is binary, and the registry explicitly indicates that a two-arm comparison is not estimable. The observed counts therefore cannot yield a useful estimate of comparative effect or its precision.

The trial is listed as terminated, but the reason for termination is not reported in the registry record. It is also not reported whether the enrollment of 2 was planned, whether recruitment stopped early, or what target enrollment was intended. Without this context, the relationship between the reported enrollment and the trial’s intended scope cannot be assessed.

Details needed to evaluate trial conduct are not reported in the registry record, including eligibility criteria, participant flow, baseline characteristics, randomization procedures, allocation concealment, and masking of outcome assessors. The provider-determined primary endpoint may depend on clinical assessment, but adjudication procedures are not reported.

Analysis populations, missing-data handling, protocol deviations, and sensitivity analyses are not reported. The registry also does not provide results for the three listed secondary outcomes, including patient-reported scores. The absence of these results limits assessment of the stated patient-centered aims and of possible differences in catheter-related outcomes.

Finally, safety figures involve one participant per arm and list no events. They cannot characterize uncommon harms or support a comparative safety conclusion. The record does not report the safety follow-up period or event-collection procedures. These trial-specific gaps make the posted results descriptive and sharply limit generalization beyond the participants reported.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Outcomes for One-stage and Two-stage Brachial Basilic Arteriovenous Fistulas — NCT04376567.
• Registry record last updated 2025-09-11; status last verified 2025-09.
• Results first posted 2025-09-11.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT04376567 is a randomized, unmasked, parallel-group pilot trial comparing one-stage with two-stage BBAVF procedures. The registry lists an enrollment of 2, a start date of 2021-10-01, a primary completion date of 2023-11-01, and a terminated status. The reason for termination is not reported in the registry record.

The primary endpoint is successful fistula use for dialysis within 6 months, defined by a provider-determined pattern of dialysis use without an additional procedure or surgery. The posted results record one successful-use outcome in each arm, with one participant reported in each arm. A two-arm comparison is not estimable.

Three secondary outcomes are listed, but their results are not reported. The safety figures list no serious adverse events, other adverse events, or deaths in either arm. The statistical analysis plan, sample-size justification, analysis populations, and missing-data procedures are not reported in the registry record. The results therefore provide a limited descriptive account and do not establish a comparative effect or safety difference.