Evaluation of Various Methods Used to Identify the Proximal Humerus Intraosseous Vascular Access Site: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Various Methods Used to Identify the Proximal Humerus Intraosseous Vascular Access Site (NCT01742780), a randomized na study. The primary outcome is Ease of Use Score.

2. Clinical Question

3. Trial Design

This was a completed, randomized, non-masked, parallel study of methods for identifying a proximal humerus site for intraosseous vascular access. The registry lists an enrollment of 60 and a phase of not applicable. The study start and primary completion are both recorded as 2012-12. The sponsor was Vidacare Corporation.

The registry describes four clinician method arms: Campbell, Davlantes, Saussy, and Standard Vidacare. In these descriptions, clinicians with no prior training in identifying the site were trained in a method and performed one unilateral proximal humerus insertion. The method-specific arm descriptions are truncated in the registry record, so their full procedural instructions are not available there.

The registry also describes two healthy-subject groups receiving bilateral procedures: one pairing Campbell with Saussy, and another pairing Davlantes with Standard Vidacare. These descriptions indicate that each method in a pair was used on one proximal humerus. The registry’s parallel-model classification appears alongside these descriptions; further details about how the different groups related to randomization are not reported in the registry record.

The primary outcome was the operator’s perceived ease-of-use score within 10 minutes of the procedure. The posted outcome summaries give a mean and standard deviation for each of the four clinician method arms. They report 10.0 participants for Campbell, 9.0 for Davlantes, 10.0 for Saussy, and 10.0 for Standard Vidacare. The stated reason for the Davlantes outcome count is that one participant’s procedure was terminated by the investigator and that participant did not complete the ease-of-use question.

The registry lists four outcome measures and no posted registry analyses. Details of the original sample-size rationale, allocation procedure, and analysis plan 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: Healthy volunteers had a physical exam to confirm no excess tissue was overlaying the proximal humerus IO insertion site and adequate landmarks were visible. Clinicians were trained on and had to correctly demonstrate their assigned method for IO vascular access in the proximal humerus for approval to participate as a device operator.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: One participant in the Davlantes Method for Intraosseous Insertion arm had their unilateral proximal humerus IO site insertion procedure terminated by the investigator. Since the procedure was terminated the participant did not complete the Ease of Use Question. Therefore only 9 participants were included in the Davlantes Method for Intraosseous Insertion arm analysis for this outcome measure.

5. Baseline Characteristics

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

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Ease of Use Score, measured over Within 10 minutes of procedure.

The primary endpoint was the device operator’s perceived ease of using the assigned method to identify the site for a proximal humerus intraosseous insertion. Operators scored ease within 10 minutes of the procedure on a scale ranging from 0 to 10. A score of 0 represented extremely difficult, and a score of 10 represented extremely easy; higher values therefore represented greater perceived ease.

This endpoint is a continuous measure: it records a numerical score across a scale rather than only whether a procedure met a yes-or-no criterion. Reporting the mean describes the average rating within an arm, while the standard deviation describes how much individual ratings varied around that mean. Both are useful because an average alone does not show whether operators’ experiences were similar or widely spread.

The measure captures the operator’s perception of ease, not an independently measured clinical outcome. It should therefore be interpreted as a rating of the site-identification method as used in the study, rather than as a direct measure of access success, speed, safety, or patient benefit. Those are distinct outcomes, and the registry’s primary endpoint does not establish them.

The registry specifies the scoring scale and the time frame for assessment. More detailed information about how the question was administered, whether operators received common instructions for rating, and how the scale was handled in the analysis is not reported in the registry record.

7. Results Posted in the Registry

• Campbell Method for Intraosseous Insertion: mean 9.60 versus 8.30 on control; difference 1.30 (95% CI 0.57 to 2.03), standardized effect d = 1.56; z-test p = <0.001.
• Saussy Method for Intraosseous Insertion: mean 8.60 versus 8.30 on control; difference 0.30 (95% CI -1.25 to 1.85), standardized effect d = 0.17; z-test p = 0.705.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous score, and the registry reports each arm’s mean and standard deviation. A mean gives the arithmetic center of the ratings in an arm. A standard deviation describes the typical spread of individual ratings around that center. When the score is bounded from 0 to 10, the observed means and standard deviations should be understood in the context of that scale; they are not counts of successful procedures or probabilities.

What does a mean difference represent?

A mean difference compares two arm averages by subtracting one from the other. In the posted comparisons, the reference mean is the Standard Vidacare mean, and the other mean is for Campbell or Saussy. A positive difference therefore indicates a higher average rating for the named method than for Standard Vidacare. Since higher scores indicate greater perceived ease, the direction of the estimate is consistent with a higher average ease rating. This is a comparison of averages, not a statement that every operator preferred one method.

The posted Campbell comparison has an estimated mean difference of 1.3, based on means of 9.6 for Campbell and 8.3 for Standard Vidacare. The Saussy comparison has an estimated mean difference of 0.3, based on means of 8.6 and 8.3. The standard deviations are not identical across arms, and the observed groups are small. Individual ratings can therefore vary, and estimates from small groups can be imprecise.

How should the confidence interval be read?

A confidence interval gives a range of values compatible with the data and the calculation method, expressing uncertainty around an estimated difference. It is not a range containing a fixed proportion of individual participant scores, and it is not a guarantee that the true difference lies within the displayed endpoints. An interval that includes zero is compatible with no mean difference, as well as with differences in either direction. An interval entirely on one side of zero indicates that the range of estimates under that calculation does not include zero.

For Campbell compared with Standard Vidacare, the posted interval is above zero. For Saussy compared with Standard Vidacare, the interval extends from -1.254 to 1.854 and includes zero. The interval’s breadth matters as well as whether it crosses zero: it conveys how much uncertainty remains about the size and direction of the difference. The confidence level used for the posted intervals is not reported in the registry record.

What does a p-value tell the reader?

A p-value describes how unusual data at least as inconsistent with a specified null model would be if that model and the test assumptions were correct. It is not the probability that the null hypothesis is true, nor does it measure the practical importance of a difference. The posted unadjusted p-value is < 0.001 for Campbell compared with Standard Vidacare, and 0.705 for Saussy compared with Standard Vidacare. These are recalculated unadjusted comparisons from the posted summary statistics, not registry analyses. The registry record lists no analyses, and the original analysis procedures are not reported in the registry record.

Because the study evaluates four methods and the posted comparisons cover only two comparisons against Standard Vidacare, the p-values do not answer every possible comparison. If multiple comparisons are considered together, the chance of obtaining at least one apparently unusual result can differ from the chance attached to a single test. General statistical practice may address this through prespecified multiplicity procedures, but whether such a procedure was planned or used is not reported in the registry record. The posted p-values should consequently be read as unadjusted for multiplicity.

Why does variability matter?

General statistical explanation: variation among ratings affects how precisely an arm mean and the difference between means can be estimated. A larger spread relative to the group size generally makes an estimate less precise. The standard deviations differ across the reported arms, with greater spread in the Saussy ratings than in the Standard Vidacare ratings. That observed variation is reflected in the wide interval for the Saussy comparison. The registry does not report whether the original analysis used a method designed for unequal variances.

General statistical explanation: over-dispersion means that data vary more than a statistical model expects. It is particularly relevant when a model assumes a specific variance structure, such as a count model. The endpoint is a bounded continuous rating, and the registry does not report an over-dispersion analysis. There is no basis in the record to claim that over-dispersion was assessed or that a particular variance model was used.

The posted planning illustrations use the observed effect as a starting point and show hypothetical participant counts for smaller fractions of that effect. These calculations are distinct from the trial’s original design decisions. The original sample-size justification and its assumptions are not reported in the registry record. The planning illustrations are therefore useful for understanding how assumptions about a target effect change a projected sample size, but they do not establish what the trial was designed to detect.

10. Confidence Intervals and Precision

Precision concerns how narrowly the data locate an estimated difference. A point estimate gives one value, while its confidence interval shows a range reflecting uncertainty under the calculation used. A narrow interval would indicate greater precision than a wide one, all else equal. Neither interval width nor a p-value alone tells the reader whether a difference matters in practice; that judgment would require a meaningful threshold for the ease-of-use scale, which is not reported in the registry record.

For Campbell compared with Standard Vidacare, the estimated mean difference is 1.3 points and the posted confidence interval lies entirely above zero. This supports a positive difference in average ratings under the recalculated comparison, while the interval’s exact lower endpoint is not repeated because it is recorded to more than three decimal places. The arm summaries are based on 10.0 participants each, so the estimate is grounded in limited data.

For Saussy compared with Standard Vidacare, the mean difference is 0.3 points and the confidence interval runs from -1.254 to 1.854. This interval includes zero and spans both negative and positive differences. It therefore leaves substantial uncertainty about the direction and magnitude of a difference, despite the point estimate being positive. It does not demonstrate equivalence.

The Davlantes mean is based on 9.0 participants, and one participant did not complete the rating after the procedure was terminated. No confidence interval or recalculated comparison involving Davlantes is posted. The descriptive mean and standard deviation alone do not quantify uncertainty in the same way as an interval for a contrast.

Confidence-interval level, prespecified precision goals, and an accepted clinically or operationally meaningful score difference are not reported in the registry record. These omissions limit how finely the estimates can be interpreted, especially when considering whether the size of an observed difference would matter outside the study.

11. 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 sample-size illustrations give participants per arm for the two-arm comparisons; they are not total event counts. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set to the stated fraction of the observed effect. The trial’s own original sample-size assumptions are not reported in the registry record.

The 80% power column gives the projected number of participants per arm for a planning scenario intended to have an 80% chance of detecting the specified effect under the listed assumptions, if that effect and the calculation assumptions are correct. The 90% power column uses a higher target chance of detecting that same specified effect and therefore generally requires more participants per arm. These are planning calculations, not evidence about what the completed study could or could not detect. This is not observed power.

The rows use 100%, 75%, and 50% of the observed effect. They illustrate how the projected sample size changes when the target difference is smaller than the difference observed in this study. For both posted comparisons, planning for a smaller fraction of the observed effect requires more participants per arm. The resulting counts vary markedly by comparison because the observed effects and variability differ.

These figures are illustrative rather than a reconstruction of the original protocol. They are based on observed summary statistics and stated planning assumptions, not on the registry’s original design rationale. The table and curve should therefore be read as conditional planning aids: different target effects, analysis choices, or assumptions could yield different projected counts. They do not show the number enrolled or assessed in the trial, and they do not replace a prospective sample-size justification.

12. 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 = 1.300; pooled standard deviation σ = 0.834.
2. n = 2 × (1.96 + 0.842)² × 0.834² / 1.300² = 6.5, rounded up to 7 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 <- 1.3                      # observed difference in means
sigma <- 0.834415963413932                     # 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(1742780)
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 = 7 (80% power), 9 (90% power)
 75% of observed effect: n per arm = 12 (80% power), 16 (90% power)
 50% of observed effect: n per arm = 26 (80% power), 35 (90% power)
power.t.test: 7.6 
Simulated power at n = 7 per arm: 0.757 (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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and no posted registry analyses. It does not report a statistical analysis plan, a prespecified hierarchy of outcomes, or a multiplicity adjustment. The recalculated p-values for Campbell and Saussy compared with Standard Vidacare are explicitly unadjusted. They should be interpreted as results for those individual comparisons rather than as family-wise conclusions covering all methods and possible comparisons.

The record identifies the primary endpoint and its measurement time frame, but the registry does not report whether the analysis population was defined in advance, whether all randomized participants were intended to be included, or how deviations from the assigned method were handled. The primary outcome summaries give 10.0 participants for Campbell, 9.0 for Davlantes, 10.0 for Saussy, and 10.0 for Standard Vidacare. For Davlantes, the registry says one procedure was terminated by the investigator and that the participant did not complete the ease-of-use question. The posted endpoint summary consequently excludes that rating. Further details of missing-data handling are not reported in the registry record.

There is no description of an imputation method, a sensitivity analysis for missing ratings, or a rule for handling incomplete procedures. Nor does the record explain whether the termination was related to the ease-of-use assessment or to the method’s performance. It would be inappropriate to assume a reason beyond the stated termination and absent questionnaire response.

The registry separately describes healthy subjects who received bilateral method pairings, in addition to the clinician arms with unilateral procedures. Whether those observations contributed to the primary outcome summaries or to any other analysis is not reported in the registry record. The available summaries are identified by method arm, but the relationship between the different populations, the randomization process, and the analysis populations is not fully described. These reporting gaps make it difficult to reconstruct the complete inferential plan or to assess the impact of missing outcome data and multiple comparisons.

14. 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 adverse-event record reports serious adverse events for six groups: the four method arms and two healthy-subject groups. Each group lists 10 participants at risk, 0 participants affected by a serious adverse event, and 0 deaths. No serious adverse-event terms are listed.

These figures mean that the registry reports no serious adverse events or deaths in the recorded groups. They should not be read as proof that serious events cannot occur, especially because the group sizes are limited. Zero observed events describe what was recorded during this study; they do not provide a precise estimate of the frequency of rare events.

The record also includes counts for other, non-serious adverse events. It lists 8 affected participants in the Healthy Subjects: Campbell and Saussy Methods group and 9 in the Healthy Subject: Davlantes and Standard Vidacare Methods group. The four clinician method groups each list 0 participants affected by other adverse events. Those non-serious counts are distinct from the serious-event figures. The registry’s adverse-event counts do not by themselves establish that any method caused or prevented an event, and further details about event types and attribution are not reported in the registry record.

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

The posted results describe how operators rated the ease of four proximal humerus site-identification methods in this study. Campbell had the highest reported mean score at 9.6, while the other reported means were 8.33 for Davlantes, 8.6 for Saussy, and 8.3 for Standard Vidacare. Because higher values represent greater perceived ease, the Campbell group’s average rating was higher than the Standard Vidacare average in the posted comparison. The recalculated difference was 1.3 points, with an unadjusted p-value of < 0.001.

The Saussy average was also higher than the Standard Vidacare average, by 0.3 points in the recalculated comparison, but its interval includes zero and its unadjusted p-value is 0.705. That result is inconclusive about whether the average ratings differ. It is not evidence that the methods are equivalent, and it does not show that their individual ratings are the same.

These results concern perceived ease-of-use scores. They do not establish that a method improves the chance of successful access, reduces procedure time, changes clinical outcomes, or is safer. The endpoint and summaries do not answer those questions. Nor do the two posted recalculated comparisons establish a complete ranking of all four methods: no recalculated Davlantes comparison is posted, and not every pair of methods is compared.

The study’s reported method-arm groups are small, and one Davlantes rating is absent after an investigator-terminated procedure. The registry also describes separate healthy-subject bilateral method pairings, but does not fully report their relation to the primary outcome summaries. Together with the lack of a posted analysis plan and multiplicity approach, these features counsel against treating an observed mean difference as a definitive general conclusion. The data support a description of ratings in the reported groups, with uncertainty that is particularly evident in the Saussy comparison.

16. Why This Trial Matters Statistically

This study is statistically useful because its outcome is a subjective rating on a defined numerical scale. That makes it possible to examine both average perceived ease and the spread of ratings, while also making clear that a score is not the same as an objective success measure. The distinction between what the endpoint captures and what it does not capture is central to interpreting comparisons between procedural methods.

The arm summaries also illustrate why estimates should be read with their uncertainty. Campbell’s mean difference from Standard Vidacare is positive and its posted interval excludes zero, whereas the Saussy interval spans negative and positive differences. A point estimate alone would obscure that contrast in precision. Conversely, the uncertainty does not erase the observed pattern: it identifies how limited the data are for locating the possible difference.

The record additionally highlights the importance of transparent reporting. Four methods were evaluated, but the posted recalculated contrasts cover Campbell and Saussy against Standard Vidacare. The registry reports no analyses, and the multiplicity strategy and original sample-size rationale are not reported in the registry record. These omissions affect how readers should treat unadjusted comparisons and how confidently the results can be generalized beyond the reported groups.

Finally, the study illustrates the difference between a trial’s observed sample and a planning calculation. The sample-size illustrations use fractions of observed effects under stated assumptions. They are not observed power and do not reveal the assumptions behind the original design. Keeping descriptive results, inferential comparisons, and hypothetical planning calculations separate helps prevent overstatement of what the study establishes.

17. 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 arise from the information recorded about this particular study. The primary outcome is an operator-reported ease score, so the results reflect perceived usability rather than a direct measure of successful vascular access or another clinical endpoint. The registry does not report a threshold for a meaningful change in score, making it difficult to judge the practical importance of the 1.3-point Campbell comparison from the endpoint alone.

The reported method-arm outcome counts are 10.0 for Campbell, 9.0 for Davlantes, 10.0 for Saussy, and 10.0 for Standard Vidacare. One Davlantes procedure was terminated by the investigator, and the participant did not complete the ease-of-use question. The reason for the termination and its relationship to the outcome are not reported in the registry record. The registry does not report how missing ratings were handled beyond the resulting arm count.

The registry describes both unilateral clinician procedures and bilateral procedures in healthy subjects, but the relationship between these groups and the posted primary outcome summaries is not fully reported. The full arm-method instructions are truncated, limiting assessment of the exact procedural differences. Further details about operator characteristics, training standardization, allocation implementation, and the analysis population are not reported in the registry record.

Only two recalculated method comparisons are posted, and they are unadjusted. There are no registry analyses, and the original analysis plan, multiplicity approach, confidence-interval level, and sample-size justification are not reported in the registry record. These gaps limit assessment of the intended statistical framework and the completeness of comparisons across all four methods. The study’s enrollment is 60, but the reported primary outcome arm counts are smaller; the registry does not fully explain how all enrolled participants map to these outcome groups.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Evaluation of Various Methods Used to Identify the Proximal Humerus Intraosseous Vascular Access Site — NCT01742780.
• Registry record last updated 2026-04-17; status last verified 2026-03.
• Results first posted 2026-04-17.
• 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.

21. Record Summary

The registry record describes a completed randomized, non-masked, parallel study of four methods for identifying the proximal humerus intraosseous access site. Enrollment was 60, and the primary outcome was an operator-rated ease-of-use score from 0 to 10, with higher scores indicating greater ease.

Reported mean scores were 9.6 for Campbell, 8.33 for Davlantes, 8.6 for Saussy, and 8.3 for Standard Vidacare. Recalculated unadjusted comparisons against Standard Vidacare show a Campbell mean difference of 1.3 with p < 0.001, and a Saussy mean difference of 0.3 with p = 0.705. No recalculated Davlantes comparison is posted. No serious adverse events or deaths were recorded in the listed groups.

The record does not report the original sample-size justification, statistical analysis plan, multiplicity approach, or full details connecting the different participant groups to the primary outcome summaries. The findings describe operator ratings in the reported groups and do not establish effects on clinical outcomes.