Blood Sampling Functionality of Extended Dwell Catheters: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Blood Sampling Functionality of Extended Dwell Catheters (NCT04409418), a randomized na study. The primary outcome is Blood Sampling Functionality.

2. Clinical Question

The central contrast is between catheter locations. The stated outcome is functional duration for blood sampling, rather than a general measure of catheter performance or a patient-reported outcome. The record also lists catheter dwell time or survival and thrombosis as secondary outcomes, but these do not replace the primary question about aspirating blood. The registry record identifies the trial as randomized and parallel-group. It does not report the precise process used to generate the random assignment or details about which patients were eligible to take part. The clinical question is therefore specific about the placement comparison and measured function, while the available description leaves some aspects of the target population and implementation unspecified.

3. Trial Design

The registry record describes NCT04409418, “Blood Sampling Functionality of Extended Dwell Catheters,” as a completed randomized, parallel-group trial. Its official title frames the comparison as blood-sampling functionality based on catheter site selection. The record lists an enrollment of 100 and identifies Corewell Health East as the sponsor. The trial is listed as not applicable for phase. Its start date is 2021-06-23, and its primary completion date is 2023-09-30.

Participants were assigned to an experimental group with forearm placement or a control group with upper-arm placement. In the experimental group, the catheter was placed in the forearm at least 10 cm from the antecubital fossa. In the control group, the catheter was placed in an upper-arm vein at least 2 cm above the antecubital fossa. The record lists extended dwell catheters as the device intervention. It does not describe a comparison between different catheter devices.

The study is listed as open label, meaning masking is recorded as none. The registry record does not report whether outcome assessors or other staff were masked separately from patients and inserters. It also does not report how the randomization sequence was generated, whether assignment was concealed before placement, or whether any stratification or blocking was used. These are relevant design details because random assignment alone does not describe every safeguard in the allocation process.

The primary outcome was blood-sampling functionality, measured in hours during hospitalization, up to 30 days. Daily blood draws before discharge were used to assess whether blood could still be aspirated. The registry record lists catheter dwell time or survival and thrombosis as secondary outcomes over the same stated timeframe. It does not report a participant-flow account, reasons for any missing outcome measurements, or the analysis population used for each result. Those omissions limit how fully the reported arm results can be connected to the enrollment figure and the conduct of follow-up.

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: 100 were consented. Prior to randomization, 9 patients were excluded for inadequate vessel size, 2 patients withdrew from the study, 1 patient investigator removed due to other IV access. 20 patients originally assigned to the forearm group crossed over to the upper arm group because there was no suitable target vessel, leaving 24 in the forearm group and 64 in the upper arm group.

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 Blood Sampling Functionality, measured over During hospitalization, up to 30 days.

The primary endpoint is the number of hours from catheter use until failure to aspirate blood is identified during follow-up in hospital. The record says blood-sampling ability was evaluated by daily blood draws before discharge, with the assessment period described as during hospitalization, up to 30 days. The reported outcome is a mean, with standard deviation as the measure of spread.

This endpoint addresses a practical function of an EDC: whether it continues to permit blood sampling. It focuses on the duration of that function, not simply whether a catheter was inserted or whether it remained in place. That distinction matters because blood-sampling function and catheter dwell time are listed as separate outcomes. A catheter could remain in place while its ability to provide blood samples has failed; the registry record treats those as different measurements rather than interchangeable endpoints.

Using hours preserves information about when failure was identified, rather than reducing the outcome to a simple count of catheters that did or did not fail. In general, a duration measure can help describe how long a function persists. Its interpretation depends on how failure is defined, when assessments occur, and how observations that end before a failure are handled. The registry record specifies daily assessment and the failure-to-aspirate criterion, but does not report further operational detail, such as how an exact failure time was assigned between assessments or how follow-up ending before observed failure was handled.

The endpoint therefore represents observed blood-sampling functionality during hospitalization, not necessarily the full possible lifespan of every catheter. Its meaning is bounded by the stated follow-up period and the details of assessment that are reported.

7. Results Posted in the Registry

• Experimental Group: mean 70.19 versus 112.90 on control; difference -42.71 (95% CI -85.19 to -0.23), standardized effect d = -0.34; z-test p = 0.049.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Catheter Dwell Time/Survival

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Experimental Group: mean 74.27 versus 115.52 on control; difference -41.25 (95% CI -83.18 to 0.68), standardized effect d = -0.33; z-test p = 0.054.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Experimental Group and the control. The interval gives the range of effects that remain compatible with the data.

Thrombosis

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Experimental Group: 8.3% (2/24) versus 7.8% (5/64) on control; risk difference 0.5 percentage points (95% CI -12.3 to 13.4), risk ratio 1.07 (0.22–5.13); unadjusted two-proportion z-test p = 0.936.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Experimental Group and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes add different kinds of information to the primary blood-sampling result. Catheter dwell time or survival describes duration in place, whereas thrombosis records whether the event was observed. Their scales and clinical meanings differ from the primary measure of hours until blood can no longer be aspirated. Taken together, they address additional aspects of catheter experience, but do not directly replicate the primary endpoint.

The overall pattern does not provide a clearly precise secondary contrast that independently strengthens the primary finding. The continuous dwell-time comparison has an interval that includes no difference, and the thrombosis comparison is also imprecise. This pattern should not be reduced to a claim that secondary outcomes agree with or refute the primary result. Each endpoint has its own measurement and uncertainty, and the available record does not report a combined analysis across them.

Unadjusted secondary results carry less weight when several outcomes are examined because each additional comparison creates more opportunity for a result to appear notable by chance. In general, multiplicity procedures can control the error associated with a family of tests, but the registry record does not report whether such procedures were planned or used. The posted secondary p-values should therefore be understood as unadjusted, endpoint-specific calculations rather than as evidence that accounts for the full set of outcome comparisons.

The registry record lists two secondary outcomes and does not report formal analyses for them. The posted comparisons are recalculations from summary data. No adjustment for baseline characteristics, competing events, or multiple comparisons is reported. The absence of such details does not show that a particular procedure was or was not used outside the registry record; it means that the record cannot support a more specific account of the secondary analysis.

Secondary outcomes are most useful as context: they describe other measured features of the catheter experience and help define the scope of what was assessed. They do not turn an uncertain result into a definitive one, and they should not be used to make a broad conclusion about all catheter-related outcomes. Their role is supplementary to the primary question about blood-sampling functionality.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Catheter Dwell Time/Survival
• Thrombosis

9. Statistical Interpretation

10. Statistical Methods Explained

What does a mean difference represent?

A mean is the arithmetic average of a continuous measurement. For this outcome, the measurement is hours until failure to aspirate blood is identified. The mean difference compares the group averages, calculated as the experimental-group mean minus the control-group mean. A negative estimate therefore indicates a lower observed mean in the experimental group. It does not imply that every participant in that group had a lower value, and it does not describe the distribution of individual experiences by itself.

The posted primary mean difference is -42.71 hours. It is an unadjusted comparison: it is not reported as controlling for other participant or catheter characteristics. The registry record does not report an adjusted primary analysis or a prespecified model. This matters because an unadjusted contrast summarizes the observed separation of the group means but does not show whether an analysis accounting for other variables would produce the same estimate.

What does standard deviation tell the reader?

Standard deviation describes how dispersed measurements are around a mean. It is not the uncertainty in the mean itself and is not a confidence interval. The primary standard deviations are 61.41 hours for the experimental group and 141.5 hours for the control group. The larger control-group standard deviation indicates more spread among those reported measurements. When observations are highly variable, a mean can be a less complete description of the data, so the mean and standard deviation are best read together with the confidence interval and the group sizes.

The registry record reports outcome group sizes of 24 and 64 for the primary result. Those figures describe the denominators attached to the posted arm summaries; they do not, on their own, explain why they differ from the enrollment figure. Participant flow and the reasons for any difference are not reported in the registry record.

How should the confidence interval be read?

A confidence interval expresses uncertainty around an estimated effect. In general, it gives a range of values compatible with the data and the method used to calculate the interval. It is not a range containing a stated proportion of individual participant outcomes, and it does not assign a probability to the true effect after the data have been observed. The primary interval ranges from -85.19 hours to just below zero. The fact that it lies on the negative side indicates that the interval does not include a zero mean difference, although its upper endpoint is close to zero.

The registry record does not explicitly state the confidence level or describe the method used for the interval. The estimate and interval posted for this comparison are unadjusted recalculations from the arm summaries. The record does not list a formal sponsor analysis for the primary result. Since the discrepancy indicator is false, there is no recorded conflict between the recalculation and a sponsor analysis; that should not be mistaken for evidence that a sponsor analysis was reported.

What does the p-value add?

The unadjusted p-value is 0.049. In general, a p-value describes how unusual results at least as incompatible with a specified null hypothesis would be if that null model and its assumptions were true. It is not the probability that the null hypothesis is true, nor is it the probability that chance alone caused the observed result. It also does not measure clinical importance.

The p-value should be interpreted alongside the estimated difference and its confidence interval. Here, the estimate is in the negative direction and the interval ends just below zero, while the p-value is close to the 0.05 planning reference. The result is therefore sensitive to the threshold chosen for a binary declaration of statistical significance. The registry record does not report a multiplicity adjustment for the primary and secondary outcomes, so the posted unadjusted p-value does not account for the possibility of examining multiple outcomes.

What are the secondary outcome measures?

Catheter dwell time or survival is reported as a continuous measure in hours, with means and standard deviations by group. Thrombosis is reported as a count of participants, and its comparison is expressed as a risk difference. These outcomes have different measurement scales, so their estimates should not be interpreted as if they were the same quantity. A difference in mean hours and a difference in event probability answer different questions.

For binary outcomes, a risk difference compares the observed proportions in the groups. In general, an interval for a risk difference that spans zero is compatible with no difference as well as with effects in either direction. The thrombosis interval is broad and spans zero. The posted unadjusted p-value is 0.936. The registry record does not report a sponsor analysis for this secondary result. These data do not establish equivalence between the groups: a failure to distinguish the groups statistically is not proof that their underlying risks are identical.

Why does variability matter?

When a continuous outcome has substantial spread, individual values can vary considerably around the group average. This makes the mean difference less precise than it would be with less variable observations, all else equal. The primary group standard deviations are large in relation to the estimated difference, and the confidence interval is correspondingly broad. The posted summaries do not include the underlying participant-level distribution, so it is not possible to assess skewness, outliers, or whether a different summary would better describe the data.

In general, over-dispersion means that observed variation is greater than a model assumes. If a statistical model underestimates variation, standard errors and intervals can be too narrow and tests can appear more decisive than warranted. The registry record does not report a model-based analysis or evidence that over-dispersion was assessed. For the posted continuous outcome, the standard deviations are useful descriptive information, but they do not reveal whether model assumptions were checked.

What can the planning estimates answer?

The planning estimates illustrate how many participants per arm would be needed under stated assumptions to detect specified fractions of the observed effect at the listed power targets. They are not a reconstruction of the original trial's design, because the trial's own sample-size assumptions are not reported in the registry record. They also are not observed power. Observed results and their uncertainty are described by the estimates and intervals; a planning calculation asks a different, prospective question about a hypothetical study under its assumptions.

The planning calculation uses a two-sided significance level of 0.05, equal allocation between arms, a normal approximation, and an effect to detect set to a stated fraction of the observed effect. In general, the normal approximation simplifies the sampling distribution used in a calculation. Its suitability depends on the outcome and design; the registry record does not report additional validation or adjustments to the planning calculation. The estimated requirements should therefore be read as illustrations conditional on those assumptions, not as universal design recommendations.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data locate an effect estimate. The primary mean difference is -42.71 hours, with a confidence interval extending from -85.19 hours to just below zero. That range includes effects of considerably different magnitudes, so the point estimate should not be treated as an exact description of the underlying difference. The interval remains on the negative side, but its endpoint close to zero indicates that a small separation is compatible with the posted calculation.

The group standard deviations, 61.41 hours in the experimental group and 141.5 hours in the control group, show that measurements were dispersed around the means. Variation, group size, and analysis choices all affect precision. The registry record reports 24 observations for the experimental result and 64 for the control result. It does not report whether every randomized participant contributed a primary-outcome measurement, or how unavailable observations were handled. Without those details, it is difficult to assess the impact of missing information on the interval.

The p-value of 0.049 does not resolve this uncertainty. A p-value is not an effect-size estimate and does not show how close the estimate may be to zero or how wide the plausible range is. The confidence interval is more useful for understanding the range of mean differences compatible with the calculation, while the point estimate gives the center of that range.

For thrombosis, the posted risk-difference interval spans zero and is broad, consistent with substantial uncertainty around the group contrast. The unadjusted result does not establish that the risks are equivalent. The registry record does not report a precision target or a formal sample-size justification for the original trial, so it is not possible to determine whether the study was designed to estimate either endpoint to a particular degree of precision.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning estimates are illustrations based on the observed effect, not a report of the original design calculation. For the continuous outcomes and the binary thrombosis outcome, the listed figures are participants per arm. The registry record states that time-to-event planning tables, when present, give total events, but these posted planning figures are not presented as total events.

The calculation assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning scenario sets the effect to detect as a stated fraction of the observed effect. The trial's own original sample-size assumptions and justification are not reported in the registry record, so the planning estimates should not be read as evidence about how enrollment was chosen.

The 80% power column describes the calculated participants per arm for a hypothetical study with an 80% chance of detecting the stated effect if that effect and the planning assumptions were correct. The 90% power column gives the corresponding planning figure for a 90% chance. Power is a design property under assumptions; it is not a guarantee that a particular study will detect an effect, nor does it state the probability that a result is true.

For each outcome, the table gives planning figures for detecting 100%, 75%, and 50% of the observed effect. Smaller effects need more participants to detect under the same assumptions, which is why the estimates rise as the effect fraction becomes smaller. The thrombosis calculation is especially sensitive to the small observed risk difference, producing very large planning requirements. Such calculations should be interpreted cautiously when based on an observed effect that is itself uncertain.

These figures are not observed power. They are prospective planning illustrations generated from the posted effect estimates and stated assumptions. They do not change the interpretation of the trial's actual confidence intervals, group summaries, or unadjusted p-values.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -42.710; pooled standard deviation σ = 125.179.
2. n = 2 × (1.96 + 0.842)² × 125.179² / -42.710² = 134.8, rounded up to 135 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -42.71                      # observed difference in means
sigma <- 125.179139682408                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(4409418)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 135 (80% power), 181 (90% power)
 75% of observed effect: n per arm = 240 (80% power), 321 (90% power)
 50% of observed effect: n per arm = 540 (80% power), 723 (90% power)
power.t.test: 135.8 
Simulated power at n = 135 per arm: 0.795 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary outcome and secondary outcomes, but does not report a statistical analysis plan describing how results were to be tested or how multiple comparisons would be handled. In general, testing several outcomes increases the chance that at least one comparison will appear statistically notable even when there is no underlying effect. Procedures that account for multiplicity can address this issue, but no such adjustment is reported for these results. The posted p-values are unadjusted and should be read as outcome-specific rather than as a family-wise conclusion.

The record does not report whether the primary endpoint was formally prioritized in a prespecified hierarchy, whether secondary outcomes were exploratory, or whether any outcome definitions changed during the study. Those details matter because prespecification helps distinguish planned confirmatory questions from analyses selected after data are available. Their absence from the registry record limits assessment of how the reported comparisons relate to the original plan.

Missing-data handling is also not reported. The record does not describe the number of randomized participants with unavailable outcome measurements, reasons for missingness, imputation, or sensitivity analyses. It does not state whether participants were analyzed according to their randomized assignment or only if they had observed outcome data. The arm denominators attached to the posted results are therefore not enough to determine the analysis population or to assess whether missing observations could have affected the estimates.

The treatment of follow-up that ends before failure to aspirate blood is identified is not reported. This matters because a duration outcome can be affected by how observations without an observed failure are included or censored. The registry record gives the assessment schedule and maximum timeframe but not the statistical handling of incomplete follow-up.

There is also no reported account of interim analyses, stopping rules, or a data-monitoring process. These matters are not necessarily required for every trial, but without registry entries they cannot be incorporated into an assessment of the statistical plan. The appropriate conclusion is limited: the posted values permit descriptive and unadjusted comparisons, while the record does not document multiplicity control, missing-data methods, or analysis populations in enough detail to evaluate them.

15. 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.

Most frequent non-serious adverse event terms

The registry safety figures report no serious adverse events in either arm and no deaths in either arm. For other adverse events, the record lists 6 affected participants in the experimental group and 24 in the control group. These are counts, not rates, and the registry record does not provide further definitions or a narrative description of the events in these categories.

Counts should be read alongside the at-risk group sizes reported for each arm: 24 in the experimental group and 64 in the control group. A raw count alone does not account for differences in the number of participants at risk, length of observation, or completeness of reporting. The record does not provide a statistical comparison for these adverse-event figures, and no serious-event terms are listed.

Zero recorded serious events or deaths in the posted results is not proof that such events cannot occur. The figures describe what was reported for this trial and follow-up, rather than establishing a general safety profile. They also do not by themselves determine whether a treatment or catheter placement approach is safe or unsafe.

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

The primary result describes a difference in observed mean hours until failure to aspirate blood, comparing forearm placement with upper-arm placement. The posted mean was 70.19 hours in the experimental group and 112.9 hours in the control group, with an unadjusted mean difference of -42.71 hours. The confidence interval remains just below zero at its upper endpoint, while extending substantially farther in the negative direction. This indicates that the estimate is uncertain in magnitude even though the interval does not cross zero.

The result does not mean that every catheter placed in the forearm failed earlier, or that every catheter placed in the upper arm remained functional longer. Group means conceal individual variation, and the standard deviations show considerable spread. Nor does the result establish why the observed means differed. The registry record does not report adjusted analyses or enough detail about missing observations and follow-up to resolve those questions.

The primary endpoint is specifically blood-sampling function during hospitalization. It is not a direct measure of every aspect of catheter performance, patient experience, or longer-term outcome. Catheter dwell time and thrombosis were listed separately, and their posted results do not provide a precise corroborating contrast. The absence of a clear statistical distinction in a secondary result is not evidence that the groups are identical.

The trial is randomized, which makes the location comparison more informative than a simple observational comparison, but randomization does not remove uncertainty from a modest and variable dataset. Details of sequence generation, concealment, missing-data handling, and analysis populations are not reported in the registry record. The study was open label, and the primary endpoint involves assessment during routine blood draws. These features should inform interpretation without being used to assume bias in a particular direction.

Accordingly, the posted result is best understood as an unadjusted estimate for the specified endpoint and follow-up setting. It does not, by itself, demonstrate a universal effect of catheter location, establish equivalence or difference for all outcomes, or support a clinical recommendation. The result should be kept within the boundaries of the measured function, recorded time period, and limitations of registry reporting.

17. Why This Trial Matters Statistically

This trial is statistically interesting because its primary outcome is a duration measure that is closely tied to a specific function: the ability to aspirate blood from an extended dwell catheter. It compares two placement locations while holding the named device type constant. That makes the central statistical contrast relatively direct: a difference in mean hours until the defined functional failure is identified.

The posted estimate also illustrates why a point estimate should not be read alone. The mean difference is -42.71 hours, but the confidence interval reaches close to zero and spans a broad range of negative values. The unadjusted p-value of 0.049 is near the conventional 0.05 reference used in the planning assumptions. Together, these features show how a binary threshold can obscure the uncertainty and magnitude represented by an estimate and its interval.

Variation is another important feature. The primary outcome standard deviation is much larger in the control group than in the experimental group. This reminds readers that the average difference exists against considerable within-group dispersion. A single mean cannot convey the range or shape of participant-level outcomes, which are not reported in the registry record.

The secondary outcomes further demonstrate that different endpoints can lead to different precision. Dwell time is continuous, while thrombosis is binary; neither should be treated as simply another version of the primary outcome. The registry record also illustrates the importance of reporting analytical choices: multiplicity handling, missing-data procedures, analysis populations, and sponsor analyses are not described in sufficient detail to evaluate fully.

Finally, planning estimates based on observed effects can be informative as illustrations, but they are not the original design rationale or observed power. Distinguishing prospective planning from analysis of completed trial data is essential when interpreting the very different questions those calculations answer.

18. 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.

Several limitations are specific to the available record for this trial. The study is listed as open label, with no masking. Because the primary outcome is assessed through blood-draw attempts during hospitalization, the absence of masking may be relevant to how assessments were made, although the record does not show that assessment was biased or describe separate masking of assessors.

The primary outcome is observed during hospitalization and is assessed daily. The record does not say how the time of failure was assigned between assessments, whether assessment procedures were standardized across sites or staff, or how catheter function was handled when discharge occurred before failure. Follow-up is described as up to 30 days, so the result should not be read as a measure of function beyond that stated period.

The registry record does not report details of random-sequence generation, allocation concealment, eligibility criteria, participant flow, or the analysis population. It lists enrollment as 100, while the primary outcome summaries report 24 participants in the experimental group and 64 in the control group. Without a flow account, the reason those outcome denominators are reported as they are cannot be determined from the registry record.

Missing-data methods, adjustment for baseline characteristics, and a formal primary analysis are not reported. There is no reported statistical analysis plan explaining how multiple outcomes were handled, nor are interim analyses or stopping rules described. The posted comparisons are unadjusted recalculations from summary statistics, and participant-level distributions are unavailable. These limits make it difficult to assess sensitivity to modeling choices, missing observations, or the multiplicity of outcome testing.

The registry record also provides limited detail about the secondary outcomes and adverse-event definitions. The posted counts and estimates can be described, but they do not permit a complete assessment of event ascertainment or clinical context. These limitations constrain interpretation of the reported results; they do not establish that the trial procedures were inadequate.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Blood Sampling Functionality of Extended Dwell Catheters — NCT04409418.
• Registry record last updated 2024-11-15; status last verified 2024-11.
• Results first posted 2024-11-15.
• 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.

22. Record Summary

NCT04409418 is a completed, randomized, open-label, parallel-group trial sponsored by Corewell Health East. It compared extended dwell catheter placement in the forearm with placement in the upper arm. The primary outcome was hours until failure to aspirate blood during hospitalization, assessed through daily blood draws before discharge and followed for up to 30 days.

The posted primary means were 70.19 hours for forearm placement and 112.9 hours for upper-arm placement. The unadjusted mean difference was -42.71 hours, with a confidence interval extending from -85.19 hours to just below zero and an unadjusted p-value of 0.049. The registry record also lists catheter dwell time or survival and thrombosis as secondary outcomes.

The record does not report a formal sponsor analysis, multiplicity procedures, missing-data methods, or the original sample-size assumptions. The posted comparisons support an unadjusted statistical description, with uncertainty that should be considered alongside the observed estimates.