Buttonhole Versus Step Ladder Cannulation in High Dose Hemodialysis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Buttonhole Versus Step Ladder Cannulation in High Dose Hemodialysis (NCT01962025), a randomized na study. The primary outcome is Feasibility of Participant Recruitment and Site Coordination.

2. Clinical Question

This was a feasibility question, not a registry-posted test of whether either needling technique is clinically superior. The pilot description identifies two practical uncertainties: whether patients would agree to random assignment between the two techniques, and whether sites could coordinate the study and produce useful multicentre data. The primary outcome is titled “Feasibility of Participant Recruitment and Site Coordination” and describes the percentage of qualified patients enrolled as the benchmark for deciding whether to move forward. The registry record does not provide the number of qualified patients approached or eligible, so the enrolled proportion and whether it met the benchmark cannot be determined from the posted figures. It also does not report a comparative effect estimate for a clinical outcome. The record lists participant counts in each arm, but those counts alone do not answer the recruitment-rate question or establish whether the participating sites coordinated successfully.

3. Trial Design

The registry describes a randomized, unmasked, parallel-group trial with an enrollment of 14 and status “Completed.” It lists buttonhole needling technique and step ladder needling technique as the two study approaches. The arm descriptions specify buttonhole needling for home hemodialysis and use of the step ladder technique in the comparison group. The posted arm counts are 8 for buttonhole and 6 for step ladder. The trial is listed under renal failure, and its phase is recorded as not applicable.

The study is identified as a pilot feasibility trial. Its stated purpose was to assess whether patients would agree to randomization between needling approaches and whether multiple sites could coordinate the work and generate useful trial data. The primary outcome timeframe is 2 years. The record lists the start as 2013-10 and primary completion as 2017-11. It does not state the number of sites, how participants were recruited, the randomization sequence method, allocation concealment, or whether assignment was stratified. Those design details are not reported in the registry record.

The randomized and parallel labels describe the recorded overall design; “unmasked” indicates that the study is not recorded as masked. The registry record does not describe whether outcome assessment or data analysis was masked separately. It names Ottawa Hospital Research Institute as sponsor. These details frame the pilot as a small feasibility investigation. The record does not specify a planned definitive-trial design, nor does it give a protocol-level explanation of how the pilot findings would be used to make a continuation decision beyond the stated recruitment benchmark and site-coordination aims.

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

Analysis population for the primary outcome, as defined in the registry: Intent to Treat (ITT)

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 Feasibility of Participant Recruitment and Site Coordination, measured over 2 years.

The primary endpoint is titled “Feasibility of Participant Recruitment and Site Coordination.” Its description says the pilot would assess the percentage of qualified patients enrolled, with a stated success target of ≥70%. If the target could not be reached, the definitive study would not move forward. The outcome also was intended to help assess whether multiple sites could coordinate needling techniques and whether a definitive study could proceed. The recorded timeframe is 2 years, and the population is identified as ITT.

This kind of endpoint is used to assess whether a larger study can be conducted, rather than to establish the comparative clinical effect of the assigned techniques. Recruitment and coordination are practical conditions for a multicentre trial: the recruitment measure concerns whether eligible, qualified patients enter the study, while coordination concerns the ability of sites to carry out the work and produce usable data. The registry record does not define a separate numeric site-coordination measure or its success threshold.

The posted arm values are participant counts, not a reported recruitment percentage. The number of qualified patients who could have enrolled is not reported in the registry record. Therefore, the posted counts cannot establish whether the ≥70% recruitment target was met. The record also provides no primary-outcome analysis or site-level results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry labels the study randomized, unmasked, and parallel. A randomized design assigns participants to study groups by chance, which is intended to reduce systematic differences between groups at assignment. “Parallel” means the listed groups are followed as separate groups rather than participants crossing between interventions as part of the recorded design. The record does not report the randomization procedure, allocation concealment, or the details of follow-up. “Unmasked” is the recorded masking status; whether particular outcome assessors or analysts were masked is not reported in the registry record.

What does a feasibility endpoint measure?

General explanation: feasibility outcomes ask whether a future study can be carried out as intended. Recruitment can be summarized as a proportion only when both the number enrolled and the relevant pool of qualified patients are known. The primary outcome description sets a target of ≥70% of qualified patients enrolled, but the denominator needed to evaluate that target is not reported in the registry record. The participant counts by arm are not a substitute for the number of qualified patients who could have enrolled. Likewise, a stated aim to examine site coordination needs a reported measure or account of coordination; no such result is posted in the record.

The outcome title combines recruitment and site coordination, but the description does not give a separate operational definition or threshold for site coordination. That makes it important to distinguish the stated purpose from reported results: an aim to investigate coordination does not itself show whether coordination was successful. The record also does not give a formal decision rule beyond the recruitment target, nor does it report a decision about proceeding to a definitive study.

Why is there no two-arm effect estimate?

The posted primary data are participant counts, and the statistical record identifies values as missing or not estimable for a two-arm comparison of the binary endpoint. No analysis results are listed. For a comparative binary outcome, an analysis generally requires a defined event for each participant and a count of participants with and without that event in each group. The posted participant totals do not provide those outcome-event counts for the primary feasibility target. Without them, an arm comparison, confidence interval, or p-value cannot be reported from the registry data.

General explanation: a confidence interval expresses the range of estimates compatible with the observed data under a specified method. It communicates precision as well as direction and magnitude. A p-value addresses how compatible data are with a specified null hypothesis and model; it is not a measure of effect size or the probability that a hypothesis is true. Neither can be interpreted when the corresponding estimate and analysis are not reported. No interval or p-value for the primary outcome is reported in the registry record.

What can the small participant counts establish?

The recorded counts describe the size of the two groups, but they do not by themselves measure recruitment feasibility or treatment effects. General explanation: estimates from small groups are often imprecise, especially when outcomes are uncommon. If no events are recorded, the observed count is still only a count in the participants followed and does not prove that the underlying event probability is zero. Precision depends on the design, outcome definition, follow-up, and analysis, details that are not fully reported in the registry record. No uncertainty intervals for the posted adverse-event counts are included in the record.

The record gives no sample-size justification, power calculation, or planned statistical analysis. Those items are not reported in the registry record. The study’s pilot purpose is stated, but it should not be assumed that the enrollment target was selected by a particular calculation or that the study was intended to test a clinical difference. General explanation: feasibility studies commonly focus on whether a larger study can be implemented and on estimating practical parameters, rather than on definitive hypothesis testing. That general point does not establish the specific design rationale for this trial.

How should planning estimates be understood?

General explanation: sample-size planning based on an observed effect is an illustration under specified assumptions, not a measure of observed power and not a report of the original design. Its result depends on the effect size, allocation, significance threshold, and statistical approximation used. The record identifies planning assumptions of a two-sided significance level of 0.05, equal allocation, and a normal approximation for such illustrations, with the target effect expressed as a fraction of the observed effect. However, no two-arm estimates are available for the posted binary endpoint, so there is no estimable effect on which to base such a planning calculation for this comparison. A planning illustration would not remedy the missing primary-outcome denominator or constitute evidence of efficacy.

Finally, the registry identifies an ITT population for the primary outcome. General explanation: an intention-to-treat approach generally analyzes participants according to their randomized assignment, regardless of adherence, but the label alone does not describe how missing outcomes, withdrawals, or protocol deviations were handled. Those operational details and any analysis implementation are not reported in 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("Buttonhole Needling Technique", "Step Ladder Group")
n      <- c(8, 6)
events <- c(8, 6)
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  Buttonhole Needling Technique  8  8  100.0  63.1  100.0  67.6  100.0  66.4  99.7
ARM  Step Ladder Group  6  6  100.0  54.1  100.0  61.0  100.0  59.0  99.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 5 outcome measures in total: the primary feasibility outcome and four secondary outcomes. The secondary topics are participant training time, cost, number of participants with complications, and pain with needling. No analyses are listed. The statistical analysis plan, any hierarchy among outcomes, and any adjustment for multiple comparisons are not reported in the registry record. Consequently, the posted entry does not support claims about which outcomes were formally tested or how the risk of false-positive findings across multiple tests was managed.

Missing-data methods are also not reported in the registry record. The record does not state whether participants withdrew, whether all outcomes were collected for every participant, how incomplete observations were handled, or whether any imputation was used. These omissions matter because an analysis can depend on both the amount and pattern of missing data. The arm counts do not provide enough information to infer completeness for each outcome.

The primary outcome population is labeled ITT, but the record does not explain how that population was implemented or whether all randomized participants contributed data to each measure. The analysis populations for the secondary outcomes are not reported in the registry record. No protocol deviations, exclusions, or per-protocol analyses are described in the posted information. Therefore, the population label should be read as a registry designation rather than as a full account of the analysis set or missing-data handling.

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 reports 0 serious adverse events among 8 participants at risk in the buttonhole group and 0 among 6 at risk in the step ladder group. For other adverse events, it likewise reports 0 among 8 at risk in the buttonhole group and 0 among 6 at risk in the step ladder group. Deaths are reported as 0 in each group. No serious adverse-event terms are listed.

These figures are event counts, not comparative risk estimates. A zero count means no event was recorded in the stated group for that category; it does not establish that the underlying risk is zero. General explanation: when groups are small, the absence of observed events can coexist with uncertainty about the frequency of uncommon events. Confidence intervals or other uncertainty estimates would help quantify that uncertainty, but none are reported in the registry record.

The record does not describe adverse-event collection procedures, event definitions, follow-up completeness, or whether all events were actively assessed. The figures should therefore be read as the safety counts posted in the registry, not as proof that the groups have the same safety profile or that no event could occur outside the recorded observation.

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

The result supports a limited description: the registry records a completed randomized feasibility trial with 14 participants enrolled, distributed as 8 in the buttonhole group and 6 in the step ladder group. The trial’s stated purpose was to assess willingness to be randomized and the ability of multiple sites to coordinate the study. Its primary outcome description set a recruitment target of ≥70% of qualified patients enrolled over a 2-year timeframe.

The posted information does not establish whether the recruitment target was met because the number of qualified patients is not reported. Nor does it provide a separate site-coordination result or a decision about whether a definitive study proceeded. The listed arm counts are not a recruitment rate. No comparative statistical analysis is posted for the primary outcome, and the registry record does not report results for the four named secondary outcomes. Thus, the available record cannot show whether either needling approach produced a different outcome.

The adverse-event counts are zero in both groups for serious and other events, and deaths are listed as zero. These counts do not establish absence of risk or equivalence between groups, particularly without uncertainty estimates, detailed event-collection information, or larger group sizes. An absence of reported comparative analysis must not be interpreted as evidence that there is no difference.

General explanation: feasibility findings can inform whether a larger study is practical, but they do not automatically answer a clinical effectiveness question. In this case, the registry’s stated feasibility aims are clear, while the posted outcome information is insufficient to quantify the recruitment proportion or site coordination. The record is therefore most useful as documentation of the trial’s design, aims, group sizes, and reported event counts, not as a definitive comparison of the needling techniques.

14. Why This Trial Matters Statistically

This trial matters statistically because its principal question is about whether a study can be conducted, not simply whether two clinical approaches differ. Recruitment and coordination are necessary elements of a future multicentre investigation, and the registry explicitly frames the pilot around patient willingness to be randomized and the ability of sites to work together. Treating those aims as feasibility questions helps avoid reading a small pilot as though it were a definitive comparison.

The record also illustrates why a denominator is essential for interpreting a recruitment target. A count of enrolled participants, even when reported by arm, does not reveal the percentage of qualified patients enrolled unless the number of qualified patients is also known. The registry sets a threshold of ≥70%, but does not post that denominator or a calculated recruitment percentage. The counts alone therefore cannot show whether the stated benchmark was reached.

There is a second statistical lesson in the distinction between no posted analysis and a null result. The record contains no analyses and does not provide a comparative estimate for the primary endpoint. That is not evidence that the approaches are equivalent. Likewise, zero adverse-event counts in small groups do not demonstrate zero underlying risk. Clear reporting of outcome definitions, denominators, uncertainty, missing data, and analysis methods is needed to make estimates interpretable.

Finally, the trial shows the value of separating practical feasibility outcomes from clinical outcomes. The registry names secondary topics such as training time, cost, complications, and needling pain, but does not post their results. Without those estimates, readers should not infer that the trial established either practical or clinical advantages. The statistical contribution of the record is chiefly to identify the intended feasibility questions and the limits of what can be concluded from the posted counts.

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 chief limitation for interpretation is that the registry record does not report the denominator of qualified patients needed to evaluate the primary recruitment target. It gives the target as ≥70% and reports arm counts, but no number approached, eligible, declining, or enrolled as a fraction of those qualified. The record also does not post a quantitative result for site coordination, even though coordination is part of the primary outcome title and the pilot’s stated purpose.

No statistical analyses are listed, and the primary binary comparison is identified as not estimable from the posted values. No comparative effect estimate, confidence interval, or p-value is reported. The four secondary outcomes are named, but their results are not available in the registry entries. This leaves both the feasibility question and any secondary comparisons unresolved in the posted record.

Design and conduct details are limited. The record does not report the number of sites, recruitment process, randomization method, allocation concealment, detailed eligibility criteria, participant characteristics, or outcome-assessment procedures. It does not provide a sample-size justification, a statistical analysis plan, handling of missing data, or information about withdrawals and protocol deviations. These details are not reported in the registry record, so their absence should not be filled by assumptions.

The safety figures consist of zero recorded serious and other adverse events in each group, with no uncertainty estimates or detailed collection information. The small arm counts restrict the interpretation of those observations, and the posted counts cannot establish equivalence or rule out uncommon events. These limitations are specific to the available record; they do not establish that the unreported procedures or results were absent from other study materials.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Buttonhole Versus Step Ladder Cannulation in High Dose Hemodialysis — NCT01962025.
• Registry record last updated 2020-09-29; status last verified 2020-09.
• Results first posted 2020-09-29.
• 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.

19. Record Summary

NCT01962025 is a completed, randomized, unmasked, parallel feasibility trial comparing buttonhole with step ladder needling for home hemodialysis. Enrollment is listed as 14, with 8 participants in the buttonhole group and 6 in the step ladder group. The primary outcome concerns recruitment feasibility and site coordination, with a stated target of enrolling ≥70% of qualified patients over 2 years.

The pilot aimed to assess willingness to be randomized and the ability of sites to coordinate the study. The registry lists four secondary outcome topics: training time, cost, complications, and pain with needling. It reports zero serious adverse events, zero other adverse events, and zero deaths in both groups. No statistical analyses are listed, and the recruitment denominator, site-coordination result, secondary-outcome estimates, and analysis methods are not reported in the registry record. The posted information therefore describes the study and counts but does not provide a comparative result for its primary question.