Powered Bone Marrow Aspiration and Core Biopsy System Compared to Manual Devices: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Powered Bone Marrow Aspiration and Core Biopsy System Compared to Manual Devices (NCT01312519), a randomized na study. The primary outcome is Subject Reported Level of Pain During Procedure.

2. Clinical Question

The clinical question is therefore a comparison of two devices for bone marrow sampling, with a patient-reported measure of procedural pain as the primary endpoint and procedure duration as a secondary endpoint. The design can estimate differences between assigned groups, but interpretation depends on the reported measurements, their precision, and what is missing from the record. In particular, the pain measure reflects participants' ratings at the specified procedural moment; it is not a general measure of pain outside that setting. The record describes randomization but does not report further details of how the sequence was generated or concealed.

3. Trial Design

The registry identifies this as a randomized, parallel-group device trial with no masking. Enrollment was 50, with 26 participants assigned to the manual bone marrow sampling device and 24 to the OnControl Bone Marrow System. The study status is completed. Its stated purpose was to compare powered and traditional manual bone marrow aspiration and core biopsy systems.

The record lists two outcome measures. The primary measure was subject-reported pain during needle insertion, assessed on Day 1 after the needle had penetrated the cortex. The secondary measure was time needed to perform the bone marrow procedure, measured from needle insertion through needle removal on Day 1. Both outcomes are continuous measures summarized by a mean and standard deviation. The registry's description says the pain scale runs from 0, no pain, to 10, worst possible pain.

Random allocation is relevant because, in principle, it aims to make the groups comparable with respect to factors that could affect measured outcomes. The record does not describe sequence generation, allocation concealment, stratification, or other implementation details, so those aspects cannot be assessed from the registry record. With no masking, participants and clinical staff could know which device was used. That is especially relevant to a subjective pain rating and could also affect how procedure time is measured or recorded.

The record names Vidacare Corporation as sponsor and lists the study phase as NA. It gives the study start as 2010-01 and primary completion as 2010-07. The trial's original sample-size justification, its planned statistical analysis, and its interim-analysis arrangements are not reported in the registry record. The enrollment count is a description of the study, not evidence by itself that the study had adequate precision for either endpoint.

The registry posts group summaries and an unadjusted comparison for the outcomes, but lists no sponsor-reported analyses. Accordingly, the reported numerical comparisons should be read as descriptive evidence about the observed groups rather than as a complete account of the trial's intended analysis plan. Details about participant flow, withdrawals, missing measurements, and the analysis populations are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: No pre-assisgnment details.

Overall Study

Analysis population for the primary outcome, as defined in the registry: as per protocol, 50 patients were enrolled in the study and randomized to the manual bone marrow sampling device or the battery powered device.

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 Subject Reported Level of Pain During Procedure, measured over Day 1 during the needle insertion.

The primary endpoint is the participant's rating of pain during needle insertion, taken after penetration of the cortex on Day 1. The record describes a 0 to 10 scale, with 0 meaning no pain and 10 meaning the worst possible pain. The registry reports the group mean and standard deviation, so the endpoint summary describes the average rating and the spread of ratings within each group.

A patient-reported measure is used because the experience of pain is subjective: the participant is the source of the rating. Comparing group means gives a straightforward summary of how reported ratings differed on average. It does not show that every participant in a group had a similar experience, and it does not capture all possible aspects of pain. The standard deviation helps describe how much participants' ratings varied around the group mean.

The specified timing matters. This endpoint concerns pain during the needle-insertion stage after cortex penetration; it should not be treated as a measure of pain at other stages or later times. The registry does not report additional pain assessments or a broader pain outcome. The absence of masking is also relevant when interpreting a subjective rating, because participants knew which device was used.

The endpoint is appropriate to the stated hypothesis about pain during the procedure, but the posted summaries alone do not establish how the assessment was administered beyond the registry description. Details such as missing ratings, the handling of incomplete observations, and the planned method of analysis are not reported in the registry record.

7. Results Posted in the Registry

• Manual bone marrow sampling device: mean 3.80 versus 3.20 on control; difference 0.60 (95% CI -0.85 to 2.05), standardized effect d = 0.23; z-test p = 0.418.

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.

Time Necessary to Perform the Bone Marrow Procedure

• 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:
  • Manual bone marrow sampling device: mean 224.10 versus 100.00 on control; difference 124.10 (95% CI 82.02 to 166.18), standardized effect d = 1.63; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Manual bone marrow sampling device than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary endpoint measures procedure duration, while the primary endpoint measures participant-reported pain. The posted results therefore address different aspects of the procedure. The broad pattern is that the pain comparison is uncertain around a small estimated mean difference, whereas the time comparison has a mean difference whose interval is separated from zero. These findings are not contradictory: a device comparison can have different patterns for distinct outcomes.

The time result may be relevant to the trial's broader stated hypothesis about the amount of time needed to perform the procedure, but it does not resolve the primary pain question. Nor does a result on one endpoint validate a result on another. Each measure has its own definition, measurement process, and potential sources of bias. Pain is a subjective rating and the trial had no masking; procedure time is expressed in seconds, but the registry does not explain timing procedures or assessor blinding.

The secondary result is an unadjusted comparison, and no sponsor-reported analyses are listed. When multiple outcomes are assessed, the chance of observing at least one apparently notable result can increase if no adjustment or prespecified testing strategy is used. The record does not state whether the sponsor adjusted for multiplicity, designated a hierarchy among outcomes, or treated the secondary endpoint as confirmatory. For that reason, the secondary finding deserves less weight as confirmatory evidence than a fully documented, prespecified analysis would carry.

This caution does not mean that the time data should be ignored. It means that the result should be interpreted as a posted unadjusted comparison whose place in the trial's analysis plan is unclear. The record gives no further secondary endpoints beyond procedure time, and no analysis details that would allow a fuller evaluation of endpoint selection or multiplicity. The relationship between the endpoints is best understood descriptively: they concern separate outcomes, and the secondary comparison cannot substitute for more precise evidence about pain.

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

• Time Necessary to Perform the Bone Marrow Procedure

9. Statistical Interpretation

10. Statistical Methods Explained

The posted outcome summaries use means and standard deviations because both pain ratings and procedure duration are treated as continuous measures in the registry. The mean is the arithmetic average within a group. The standard deviation describes the amount of variation among individual observations around that mean. It is not the uncertainty around the mean itself: uncertainty in a group mean also depends on how many observations contribute to it.

The comparison is expressed as a mean difference, with the manual group minus the OnControl group. This direction is important for reading the sign. A positive difference means that the manual-group mean is larger; a negative difference means that the OnControl-group mean is larger. A value of zero corresponds to equal group means. For pain, the estimated difference is 0.6, with a 95% confidence interval from -0.851 to 2.051. For time, the estimated difference is 124.1 seconds, with an interval from 82.02 to 166.2.

A confidence interval gives a range of values compatible with the observed data under the statistical method used. In repeated applications of a method with its assumptions satisfied, intervals at a stated confidence level would cover the underlying quantity at that level in the long run. For an individual trial, the interval indicates how precisely the mean difference has been estimated. It is not a range containing a specified proportion of participants, nor does it assign a probability to the true value after the data are observed. The width and position of the interval both matter: an interval that crosses zero allows values on either side of no mean difference.

The p-value measures how unusual results at least as discrepant from the null value would be under a model that assumes no group mean difference. It is not the probability that the null hypothesis is true, and it does not quantify the clinical importance of an observed difference. The primary comparison has an unadjusted p-value of 0.418. The secondary comparison has p < 0.001. These are unadjusted values; the registry does not report a multiplicity adjustment or the sponsor's analysis plan. A p-value also does not remove uncertainty about missing data, measurement, or design implementation.

The posted unadjusted comparisons use the group summaries and are not listed as sponsor-reported analyses. No sponsor-reported analyses are present in the registry record. That distinction matters because a registry may post outcome values without documenting all planned analytical choices. The record does not state whether the sponsor intended a different model, covariate adjustment, transformation, or other approach. It is therefore appropriate to describe the comparisons as unadjusted and to avoid claiming that they reproduce an unreported protocol analysis.

Randomization supports a comparison of assigned groups, but the statistical interpretation also depends on how randomization was implemented and how outcomes were observed. The record states that allocation was randomized and that masking was none. Details of sequence generation and allocation concealment are not reported. Since the primary endpoint is subjective, awareness of device assignment may influence ratings or their reporting. The duration endpoint is more directly timed, but the registry does not describe timing procedures or whether assessors knew the assigned device.

Over-dispersion is a general concern when the variation in observed outcomes is greater than assumed by a particular statistical model. A model that understates variation can produce uncertainty estimates that are too narrow and p-values that are too small. The posted outcome summaries include standard deviations, but the record does not document model diagnostics or a formal assessment of over-dispersion. This concept is relevant when selecting or checking a model; it does not establish that over-dispersion occurred in this trial.

The planning illustrations use a normal approximation and assume equal allocation between the two arms, a two-sided significance level of 0.05, and an effect equal to a stated fraction of the observed effect. Those are assumptions for the planning illustration, not documented assumptions for the original trial. The original sample-size rationale and analysis plan are not reported in the registry record. The planning counts are not observed power and should not be interpreted as a retrospective measure of how likely the completed study was to detect an effect.

The standard deviation and the standard error serve distinct purposes. The standard deviation describes participant-to-participant spread. The standard error describes how much an estimated quantity, such as a mean, would vary across repeated samples under a model. The uncertainty interval for a mean difference reflects the standard errors of the group estimates and the method used to combine them. It does not describe the range of individual participants' measurements.

Finally, outcome definition and analysis population are part of the method, not merely administrative details. The registry describes the primary population as the 50 enrolled and randomized patients, but it does not give a detailed account of which participants contributed to each outcome summary. It also does not report missing-data procedures, protocol deviations, or sensitivity analyses. Those omissions limit assessment of whether the posted summaries represent all randomized participants and whether conclusions would be robust to alternate assumptions.

11. Confidence Intervals and Precision

Precision is conveyed most directly by the confidence interval around a mean difference. For pain, the manual-minus-OnControl estimate is 0.6, with a 95% confidence interval from -0.851 to 2.051. The interval spans zero, so the data are compatible with a range of mean differences that includes no average difference and values in either direction. The estimate should not be read as a precise measure of the size of a difference.

The interval's endpoints are not predictions for individual participants. They express uncertainty in the estimated difference between group means under the method used. The group standard deviations, 3.0 for the manual group and 2.2 for OnControl, describe variation among participant ratings; they are not confidence limits. The registry does not post confidence limits for each group mean.

For procedure time, the manual-minus-OnControl difference is 124.1 seconds, with a 95% confidence interval from 82.02 to 166.2. This interval lies above zero, indicating that the unadjusted estimate is separated from no mean difference under the stated comparison. Its width still represents uncertainty about the size of the mean difference. The interval does not show how much procedure time varied for each individual or guarantee that every participant's experience followed the group average.

Precision depends on both variability and the amount of information available. The enrolled groups contained 26 and 24 participants, and the pain ratings showed notable spread relative to the mean differences reported. These features help contextualize the intervals without proving why they have their particular widths. The registry does not report the original precision target or sample-size justification. Confidence intervals also cannot correct for unreported missingness, measurement issues, or selective analysis. The pain estimate is less precisely determined than a reader might infer from the single point estimate alone; the interval is essential to its interpretation.

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 figures are participants per arm, not total enrollment and not total events. They illustrate the group size that a hypothetical study would need under the stated planning assumptions to detect a selected fraction of the observed effect. The assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The assumed effect is the stated fraction of the observed effect. These are planning assumptions for the illustration; the original trial's design assumptions and sample-size justification are not reported in the registry record.

The 80% power column represents the planned probability of detecting the specified effect at the stated significance level if that effect is the true one and the planning assumptions hold. The 90% column makes the corresponding target probability higher. These are design targets for a hypothetical future study, not guarantees and not descriptions of the probability that this completed trial detected an effect.

For the pain comparison, the illustrations list 306 participants per arm for 80% power and 410 for 90% power when planning for 100% of the observed effect. Planning for 75% of the observed effect gives 544 per arm for 80% power and 728 for 90% power. Planning for 50% gives 1,223 per arm for 80% power and 1,637 for 90% power. The registry also presents planning illustrations for the procedure-time comparison; those counts use the same stated assumptions and should be read as participants per arm.

Smaller effects require more participants because they are harder to distinguish from the variability in the outcome. The progression across the effect scenarios illustrates that principle. These counts are not observed power: observed power is not an appropriate way to reinterpret the completed trial's results. Instead, the illustrations show how a future design's required group size would change under the stated assumptions and chosen effect size. They do not establish that the original study was designed with those assumptions or targets.

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 = 0.600; pooled standard deviation σ = 2.647.
2. n = 2 × (1.96 + 0.842)² × 2.647² / 0.600² = 305.5, rounded up to 306 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 <- 0.6                      # observed difference in means
sigma <- 2.64701089281224                     # 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(1312519)
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 = 306 (80% power), 410 (90% power)
 75% of observed effect: n per arm = 544 (80% power), 728 (90% power)
 50% of observed effect: n per arm = 1,223 (80% power), 1,637 (90% power)
power.t.test: 306.5 
Simulated power at n = 306 per arm: 0.802 (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 record lists one primary endpoint and one secondary outcome. It does not report a planned approach to multiplicity, such as an adjustment to significance levels, a testing sequence, or a rule for interpreting several outcomes together. Without that information, the unadjusted p-values should not be treated as if they necessarily preserve a prespecified overall error rate across all analyses. This is especially relevant to the secondary outcome, whose role in the trial's confirmatory testing strategy is not documented.

Missing-data handling is also not reported in the registry record. The record gives the number randomized to each device and posts outcome summaries for those groups, but it does not say whether every randomized participant contributed a measurement to every endpoint. It does not describe missing observations, withdrawals, exclusions, imputation, or sensitivity analyses. The posted group counts therefore should not be assumed to establish complete outcome ascertainment.

The primary population description refers to 50 patients enrolled and randomized according to protocol. Beyond that description, the registry does not specify whether the analyses followed an intention-to-treat population, a per-protocol population, or another analysis set. It also does not report protocol deviations or how such deviations were handled. These details matter because excluding participants after randomization or analyzing only a subset can affect comparability and interpretation.

There are no sponsor-reported analyses listed, and the original statistical plan is not reported in the registry record. Thus, it is not possible to compare the posted results against a documented prespecified plan or determine whether additional analyses were conducted. This absence is a limit on what can be concluded from the record; it is not evidence that missing data or multiplicity problems necessarily occurred. The appropriate reading is that these procedures and analysis-population details remain undocumented.

15. Safety Results

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

Other (non-serious) adverse events

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

The registry posts zero participants affected by serious adverse events in the manual-device group among 26 at risk, and zero in the OnControl group among 24 at risk. It also posts zero participants affected by other adverse events in each group, with 26 and 24 at risk, respectively. These figures describe what is recorded for the trial; they should not be expanded into a broader claim about device safety.

The death counts are not reported in the registry record. The record also does not provide a list of serious adverse-event terms, with no serious terms listed. The absence of posted events is not the same as proof that no events occurred under every possible definition or observation method. The registry entry does not describe adverse-event ascertainment procedures, observation duration, or completeness of reporting. The group counts are small, so the figures should be read as trial-specific recorded counts rather than as precise estimates of event risk.

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

The registry's results describe average outcomes among participants assigned to the two devices in this trial. For pain, the estimated manual-minus-OnControl mean difference is 0.6, but its 95% confidence interval, -0.851 to 2.051, includes zero and spans values in both directions. That leaves substantial uncertainty about the size and direction of an average difference in pain ratings. The unadjusted p-value of 0.418 does not establish that the groups were equivalent; an absence of a statistically notable difference is not proof of no difference.

For procedure time, the posted means and unadjusted comparison indicate a difference between the observed group averages, with the confidence interval from 82.02 to 166.2 seconds for manual minus OnControl. This is a result about the recorded duration outcome in this trial. It does not by itself answer the pain question or establish effects beyond the study's procedures and participants. The registry does not report a sponsor analysis or an analysis plan that would clarify whether this was intended as confirmatory evidence.

Neither endpoint describes every participant's experience. A group mean can coexist with substantial variation across individuals, and the standard deviations for the pain measure demonstrate that ratings varied within each group. A confidence interval around a mean difference describes uncertainty in that group-level estimate, not the range of individual outcomes.

The trial was randomized, which supports comparison of assigned groups, but masking was absent and the primary endpoint was self-reported. The record does not document allocation concealment, missing-data procedures, detailed analysis populations, or multiplicity handling. These gaps limit the strength of claims that can be made from the posted summaries. They do not show that the results are invalid; they identify aspects that cannot be evaluated from the registry record.

The findings should therefore be read as trial-specific statistical evidence with different degrees of precision across the two outcomes. They do not establish a general conclusion about all bone marrow procedures, all patients, or outcomes not measured in the record. They also do not constitute medical advice. The registry contains no basis for extending these statistics into recommendations for individual care.

17. Why This Trial Matters Statistically

This trial illustrates why a clinical comparison should be read through its outcome definitions and not just through a single significance label. The primary outcome is a participant's pain rating at a particular procedural moment, while the secondary outcome is duration from needle insertion to removal. Both concern the same procedure but measure distinct dimensions. A statistical pattern in one does not automatically answer the other.

It also illustrates the importance of precision. The pain mean difference is accompanied by an interval that includes zero and allows values on both sides of it. Reporting the point estimate alone would conceal that uncertainty. The time comparison has an interval entirely above zero for the stated manual-minus-OnControl direction, but it remains an unadjusted comparison without a documented sponsor analysis. Confidence intervals, endpoint roles, and analysis status all contribute to sound interpretation.

Randomization is an important design feature, but reporting details affect how fully readers can assess the comparison. The record identifies the trial as randomized and unmasked, yet does not document sequence generation, concealment, missing-data methods, or analysis populations. The subjective primary endpoint makes the absence of masking particularly relevant to interpretation. These are not merely technical footnotes: they determine what the registry can support and where uncertainty remains.

The planning illustrations further distinguish a completed study's observed results from the requirements of a future design. Their counts depend on explicit assumptions and selected effect sizes. They cannot be used as evidence that this trial had a particular probability of success or that its original enrollment target was based on those assumptions. This distinction helps prevent retrospective power calculations from being mistaken for observed evidence.

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.

The registry record offers limited detail about trial conduct beyond randomized allocation, parallel groups, and no masking. It does not report how the randomization sequence was generated or concealed. Without those details, readers cannot assess those parts of implementation. The lack of masking is a trial-specific concern for the subjective pain endpoint, because participants could know which device was used when rating pain.

The enrolled groups were 26 and 24 participants, and the record does not report the original sample-size justification. The pain estimate has a confidence interval that includes zero and permits differences in either direction, so its precision is limited. The registry does not report a target precision or a prespecified effect size against which to judge whether the study enrollment was adequate.

The registry does not describe participant flow, endpoint-specific denominators beyond the posted groups, missing measurements, withdrawals, exclusions, or the analysis populations. It is not possible to establish from the record whether all randomized participants contributed to each endpoint or how incomplete data were handled. The original statistical plan, sponsor-reported analyses, and multiplicity procedures are also not reported.

Measurement details are limited. The pain assessment is defined by its scale and timing, but the record does not explain the administration process. Procedure time is reported in seconds and defined from insertion through removal, but details about timing and assessment are absent. There are no posted confidence limits for group means. These gaps constrain evaluation of measurement reliability and the full context of the comparisons.

Finally, the registry presents a single primary endpoint and one secondary endpoint in a trial without masking. The secondary comparison is unadjusted, and its planned inferential status is not documented. The results are therefore best understood as posted statistical summaries, with uncertainty about analysis planning and data handling, rather than as a complete report of all trial methods.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Powered Bone Marrow Aspiration and Core Biopsy System Compared to Manual Devices — NCT01312519.
• Registry record last updated 2025-12-24; status last verified 2013-07.
• Results first posted 2013-07-23.
• 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

NCT01312519 is a completed randomized, parallel-group trial comparing the OnControl powered bone marrow aspiration and biopsy system with a manual bone marrow sampling device. Enrollment was 50, with 26 participants in the manual group and 24 in the OnControl group; masking was none.

The primary endpoint was participant-reported pain during needle insertion after cortex penetration on Day 1, rated on a scale from 0 to 10. The secondary outcome was procedure time from needle insertion through needle removal. The posted pain comparison is imprecise, while the unadjusted procedure-time comparison is separated from zero. No sponsor-reported analyses are listed. Details about the original sample-size justification, analysis plan, missing-data handling, and analysis populations are not reported in the registry record.