Bundling and Unbundling the Laparoscopic Electrosurgery Cord With the Camera Cord: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bundling and Unbundling the Laparoscopic Electrosurgery Cord With the Camera Cord (NCT01707095), a randomized na study. The primary outcome is Histologic Thermal Injury to Umbilical Port Site Skin.

2. Clinical Question

The study addresses a specific procedural comparison, not a comparison of different operations or patient treatments. Its proposed concern is capacitive coupling, described in the registry summary as a potential electrosurgery complication. The outcome is tissue evidence assessed by histology rather than a patient-reported symptom or a broad clinical recovery measure. The comparison therefore asks whether the two cord arrangements coincide with different observed rates of a narrowly defined tissue finding at the umbilical port site.

The trial also recorded histologic burn evidence at the epigastric port site as a secondary outcome. That is a separate anatomical site and should not be treated as interchangeable with the primary umbilical-site outcome. The registry record does not report additional population details, such as eligibility characteristics beyond the stated operation, or further clinical questions that the trial was designed to answer.

3. Trial Design

The registry describes a randomized, controlled trial with a parallel-group model and single masking. The trial is listed as completed, with enrollment of 84. The two groups each included 42 participants in the posted primary outcome results. The record lists the phase as not applicable. The sponsor is the University of Colorado, Denver.

The study compared two operating-room cord arrangements during laparoscopic cholecystectomy. In the bundled group, the camera and active electrode cords ran together along their lengths. In the separated group, the cords were placed on opposite sides of the table and were not run adjacent to or in parallel with one another. These descriptions define the contrast; further details about how the arrangements were implemented or monitored are not reported in the registry record.

The trial start is listed as 2012-09, and primary completion as 2014-01. The registry lists Fatigue as a condition, while the study summary and outcomes focus on histologic thermal injury at port-site skin. The primary outcome was assessed at the umbilical port site, with a timeframe of 1 day. The secondary outcome was histologic burn evidence at the epigastric port site, also with a timeframe of 1 day.

The registry record does not report the randomization sequence method, allocation concealment procedures, the identity of the masked party, or whether histology assessors remained unaware of group assignment. It also does not report a detailed protocol, eligibility criteria, participant flow, or the original sample-size justification. The randomized design supports a comparison between assigned cord arrangements, but the strength of conclusions about implementation and analysis depends on details that 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.

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 Histologic Thermal Injury to Umbilical Port Site Skin, measured over 1 day.

The primary endpoint is the number of participants with histologic evidence of thermal injury at the skin adjacent to the umbilical camera port. The registry describes a shave biopsy of the umbilical port-site skin after elective laparoscopic cholecystectomy, with assessment at 1 day. The posted results record 24 participants with the finding in the bundled group and 13 in the separated group; each group had 42 participants in the primary outcome results.

Histology provides a tissue-based way to identify evidence of a burn, which is the specific outcome named in the trial summary. It differs from an assessment based only on visible appearance or symptoms. The registry summary gives the rationale that capacitive coupling may produce thermal injury and describes the biopsy assessment as a way to determine whether such injury occurs at port sites. This endpoint consequently measures a defined tissue finding at a particular location and time, rather than all possible consequences of electrosurgery or all injuries associated with the operation.

The endpoint is used because the trial's question concerns whether cord arrangement is associated with tissue evidence of thermal injury near the umbilical port. Its scope is limited: it does not by itself establish the mechanism of any observed injury, the clinical importance of each histologic finding, or effects at other sites. The registry record does not report further details about histologic criteria, grading, or adjudication.

7. Results Posted in the Registry

• Unbundled / Separated: 31.0% (13/42) versus 57.1% (24/42) on control; risk difference -26.2 percentage points (95% CI -46.7 to -5.7), risk ratio 0.54 (0.32–0.91); unadjusted two-proportion z-test p = 0.016.

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.

Histologic Evidence of Burn at the Epigastric Port Site Skin.

• 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:
  • Unbundled / Separated: 26.2% (11/42) versus 19.0% (8/42) on control; risk difference 7.1 percentage points (95% CI -10.7 to 25.0), risk ratio 1.38 (0.62–3.07); unadjusted two-proportion z-test p = 0.434.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Unbundled / Separated and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcome assesses histologic burn evidence at the epigastric port site, a different location from the primary umbilical port site. Across the posted outcomes, the secondary comparison does not mirror the primary result's directional pattern: its point estimate goes in the opposite direction, and its uncertainty interval includes no difference. This contrast means the secondary finding does not function as a straightforward confirmation of the primary result.

The endpoints are related in that both concern histologic evidence of burn at port-site skin after the operation, but they are not interchangeable measurements. A finding at one port site does not determine what will be found at another. Differences in the observed pattern across sites can reflect genuine site-specific variation, sampling variation, or other factors; the registry record does not establish which explanation applies.

The secondary result should carry less weight than the primary result because it is designated secondary and its p-value is unadjusted. When multiple outcomes are examined, the chance of obtaining a nominally notable result by chance can increase. General explanation: multiplicity procedures may control that risk by adjusting inference or by specifying a hierarchy of outcomes in advance. The registry record does not report a multiplicity adjustment or a prespecified testing hierarchy.

The secondary outcome can still contribute descriptive information about the broader pattern of port-site findings, but it does not settle the primary question or establish a general effect across all sites. No reported secondary analysis details are available in the registry record. Interpretation should therefore remain cautious and distinguish the primary assessment from the additional, less definitive endpoint.

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

• Histologic Evidence of Burn at the Epigastric Port Site Skin.

9. Statistical Interpretation

10. Statistical Methods Explained

Statistical interpretation starts with identifying the comparison and the outcome scale. The primary outcome is binary at the participant level: a participant either had histologic evidence of thermal injury at the umbilical port site or did not. The registry reports event counts and group sizes, along with risk-difference, risk-ratio, and odds-ratio estimates. These measures describe the same two-group contrast using different scales.

What does the risk difference express?

The risk difference subtracts the event frequency in the bundled group from the event frequency in the separated group, following the comparison's stated order. Its estimate is -0.262. A value below zero means the observed event frequency was lower in the separated group than in the bundled group. The confidence interval runs from -0.467 to -0.057. The risk difference is an absolute measure: it describes the gap in event frequencies on the probability scale, rather than how many times larger or smaller one frequency is relative to the other.

General explanation: an absolute measure is often useful when the practical question concerns how much the outcome frequency differs between groups. Its interpretation depends on the event definition and the population studied. It does not automatically communicate whether a histologic finding has clinical consequences, and the registry record does not report a clinical-importance threshold for this endpoint.

How do the ratio measures differ?

The reported risk ratio is 0.542, with a confidence interval from 0.321 to 0.913. A risk ratio compares event frequencies by division, with 1 representing equal frequencies. The reported odds ratio is 0.336, with a confidence interval from 0.137 to 0.823. An odds ratio compares event odds rather than event frequencies; 1 likewise represents no contrast on that scale. Both estimates are below 1 and therefore align directionally with the negative risk difference. The three measures are transformations of the same underlying group outcome information, so they should not be counted as separate evidence.

General explanation: ratio measures can express relative contrasts compactly, but an odds ratio is not the same quantity as a risk ratio. The risk difference retains the absolute scale, whereas ratio measures depend on a reference group and can be less intuitive when the underlying event frequency is not rare. The registry record does not report a rationale for selecting among these effect measures.

What does the p-value contribute?

The posted unadjusted p-value for the primary comparison is 0.016. In general, a p-value describes how incompatible the observed data are with a specified null model of no group difference, under the assumptions of the analysis. It is not the probability that the null hypothesis is true, and it does not quantify the size or clinical importance of an effect. Because the record calls this value unadjusted, it should not be interpreted as accounting for multiple outcomes or comparisons.

The registry record does not report the test used to obtain the p-value, the exact null-model specification, or whether the reported inference came from an analysis plan written before outcome data were examined. Therefore, the p-value can be described as posted, but the details needed to reproduce or fully evaluate its calculation are not reported in the registry record.

Why are confidence intervals useful?

General explanation: a confidence interval conveys the range of effect estimates reasonably compatible with the data under the method's assumptions. It combines information about the estimated contrast and its uncertainty. A narrow interval suggests greater precision than a wide interval, but interval interpretation also depends on the design, measurement, and analysis assumptions. A confidence interval is not a guarantee that the true effect lies within its endpoints.

For the primary risk difference, the interval from -0.467 to -0.057 excludes zero. That is consistent with the posted unadjusted p-value being below the conventional 0.05 significance level, although the registry record does not report the inferential procedure or its assumptions. The interval also shows that the size of the difference is imprecisely estimated: the plausible values span a range of magnitudes. The trial therefore supplies evidence of a group contrast in the posted primary results, while leaving uncertainty about its exact size.

What limits interpretation of the analysis?

The registry record does not report the original statistical analysis plan, model specification, handling of missing outcome data, or the analysis population. It lists zero reported analyses, so there is no detailed sponsor analysis description available in the record. The displayed comparisons give summary estimates, but the associated methods cannot be fully audited from the registry information. No adjustment for covariates or multiplicity is reported.

General explanation: randomized assignment can support causal interpretation when allocation is implemented as intended, outcome ascertainment is suitable, missingness is handled appropriately, and analyses preserve the comparison created by randomization. These are design and analysis considerations, not details established by the posted estimates. Here, relevant implementation details are not reported in the registry record. The result should therefore be stated as the observed randomized-group comparison, without filling in unreported procedures or treating the posted statistical significance as a complete assessment of bias or relevance.

11. Confidence Intervals and Precision

The primary risk-difference estimate is -0.262, and its 95% confidence interval extends from -0.467 to -0.057. The entire interval is below zero, so the interval is consistent with a lower observed frequency of histologic thermal injury in the separated group under the comparison's direction. At the same time, the interval covers a range of possible difference magnitudes. The point estimate should not be mistaken for a precisely known effect.

General explanation: a confidence interval represents uncertainty in an estimate under the statistical method's assumptions. It does not mean that every value inside the interval is equally likely, nor does it include all uncertainty arising from design, outcome measurement, missing data, or selective reporting. An interval can indicate compatibility with a direction of effect while still leaving substantial uncertainty about the size of that effect.

The ratio-scale intervals also exclude 1: the risk-ratio interval runs from 0.321 to 0.913, and the odds-ratio interval runs from 0.137 to 0.823. Their direction agrees with the risk-difference result. These intervals are not independent replications; they present the same underlying comparison on different scales. The risk-difference interval is especially useful for understanding the absolute contrast, while the ratio intervals describe relative contrasts.

Precision is limited by the number of participants represented in each group and the number of observed events. The registry does not report a sample-size justification or a target precision. The interval therefore communicates what can be learned from the posted results without establishing whether the study was designed to estimate the effect to a specified 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 sample-size planning figures are participants per arm, not total events. The planning illustration assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It uses the observed effect as a reference and considers planning for 100%, 75%, and 50% of that observed effect. The original trial's own design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the estimated participants per arm for a planning scenario intended to have an 80% chance of detecting the specified effect under the stated assumptions. The 90% power column gives the corresponding per-arm planning figure for a 90% chance. These are design illustrations, not descriptions of what the trial observed. Smaller effects require more participants under these assumptions, which is why planning for a smaller fraction of the observed effect yields larger per-arm figures.

These figures are not observed power. They do not indicate the probability that the trial's conclusion is correct, and they do not change the uncertainty in the posted outcome estimates. They are conditional planning calculations based on an effect drawn from the trial's observed results. Because an observed effect can be imprecise, using it as the planning reference does not ensure that a future study will have the same effect or require exactly the illustrated enrollment.

The registry record does not report that these planning assumptions were used to design this trial. They should therefore be read as illustrations of sample-size implications under the stated assumptions, not as evidence that the enrolled number was selected through that procedure. For this binary outcome, the figures refer to participants in each group, unlike time-to-event planning displays that may report total event counts.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.571; treatment proportion p₁ = 0.310; average p̄ = 0.440.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7021 = 1.3760.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6772 = 0.5700.
4. n = (1.3760 + 0.5700)² / (-0.2619)² = 55.2, rounded up to 56 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
p0 <- 0.571428571428571                          # control proportion
p1 <- 0.30952380952381                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1707095)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 56 (80% power), 74 (90% power)
 75% of observed effect: n per arm = 101 (80% power), 134 (90% power)
 50% of observed effect: n per arm = 228 (80% power), 305 (90% power)
power.prop.test: 55.2 
Simulated power at n = 56 per arm: 0.796 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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 does not report a multiplicity plan, such as an adjustment for testing more than one outcome or a prespecified hierarchy that determines which comparisons are confirmatory. The primary outcome and a secondary outcome are listed, and the posted p-values are unadjusted. The primary p-value should thus be read as an unadjusted result rather than as a value known to control a family-wise error rate across outcomes.

General explanation: when several hypotheses are tested, each test creates an opportunity for a chance finding. Adjustments or a prespecified testing sequence can address this issue, but the appropriate approach depends on the trial's aims and analysis plan. Since that plan is not reported in the registry record, it is not possible to determine whether additional outcomes were prespecified, how they were prioritized, or whether any multiplicity strategy was used outside the posted record.

Missing-data handling is also not reported. The registry provides outcome group sizes, but does not describe whether all randomized participants contributed outcome data, how unavailable biopsies or indeterminate histology were handled, or whether any imputation or sensitivity analysis was conducted. The analysis population is not defined in the posted record. Consequently, the relationship between the randomized enrollment and the outcome-analysis population cannot be fully evaluated.

The record lists zero reported analyses and does not include a detailed analysis plan, model specification, adjustment variables, or methods for addressing protocol deviations. This does not establish that no such work occurred; it means these details are not reported in the registry record. Without them, readers cannot assess whether the posted comparisons follow a prespecified plan, whether participants were analyzed according to assignment, or how robust the estimates are to alternative analytic choices.

These omissions matter for the interpretation of both the primary and secondary findings. They do not erase the posted counts and estimates, but they limit assessment of selective analysis, missingness, and the extent to which nominal statistical inference accounts for all planned comparisons.

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.

Most frequent serious adverse event terms

The registry lists zero serious adverse events among the 42 participants at risk in the bundled group and zero among the 42 participants at risk in the separated group. It lists no serious adverse event terms. Other adverse events are listed with zero participants at risk and zero affected in each group, so those entries do not provide a comparable account of non-serious events. Death counts are not reported in the registry record.

These entries describe what the safety record contains; they should not be read as proof that no adverse events of any kind occurred. In particular, the zero at-risk values for other adverse events do not establish that comprehensive non-serious-event surveillance took place. The record does not report the safety collection procedures, observation period, definitions, or whether adverse-event information was actively solicited.

The serious-event figures are therefore limited descriptive information from the registry. They do not establish that either cord arrangement has a particular safety profile, and they do not replace consideration of the trial's size, follow-up, or safety reporting methods. The record's primary focus is histologic port-site injury, not a broad safety comparison.

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

The posted primary results show fewer participants with histologic thermal injury at the umbilical port site in the separated-cord group than in the bundled-cord group. The risk-difference estimate is negative, its confidence interval excludes zero, and the unadjusted p-value is 0.016. These findings describe the trial's observed comparison and indicate a difference in the recorded primary outcome between the randomized groups.

They do not establish that separating cords prevents injury in every laparoscopic operation, that the same pattern will occur in other institutions or populations, or that the observed histologic finding has a particular clinical consequence. The trial focused on elective laparoscopic cholecystectomy and on biopsy evidence at a specified port site and timeframe. The registry record does not report a clinical-importance threshold or outcomes that would link the histologic result to later patient experience.

The results also do not establish a mechanism. The registry summary discusses capacitive coupling as a concern and describes prior work, but the posted comparison alone cannot show that any difference in histology was caused specifically by a change in capacitive coupling. Nor does the result establish that cord arrangement is the only relevant influence on the outcome. Further details about implementation, adherence, outcome assessment, and analysis are not reported in the registry record.

The secondary epigastric-site result has a different point-estimate direction and substantial uncertainty. It should not be used to claim a uniform pattern across port sites. The distinction between primary and secondary outcomes is important, particularly because the secondary p-value is unadjusted and the registry does not report a multiplicity plan.

In general, randomized assignment strengthens a group comparison when carried out and analyzed as intended. However, the registry record does not provide all details needed to assess those conditions. The appropriate conclusion is therefore limited to the reported outcome counts and estimates, with uncertainty and reporting gaps kept in view. The findings are not medical advice and do not by themselves determine a clinical or procedural decision.

17. Why This Trial Matters Statistically

This trial is statistically notable because it tests a concrete procedural contrast with a tissue-based binary outcome and reports both absolute and relative measures. The risk difference communicates the absolute direction and magnitude of the group contrast, while the risk ratio and odds ratio express the same comparison on relative scales. Seeing the measures together can help readers distinguish effect scale from evidential strength.

The primary estimate and interval illustrate why a single point estimate is not enough. The reported interval excludes zero, yet it spans a range of possible effect sizes. Statistical evidence for a directional contrast and precision about its magnitude are related but distinct questions. The posted results support describing the observed difference while still emphasizing uncertainty in how large that difference may be.

The secondary endpoint also illustrates why results should be interpreted by outcome role and not just by whether a p-value crosses a threshold. The primary and secondary patterns differ, and the secondary inference is unadjusted. That makes multiplicity, outcome hierarchy, and cautious interpretation important statistical issues, even when the outcomes are biologically related.

Finally, the registry record highlights how much interpretation depends on reporting. The randomized parallel design and equal group sizes are stated, but the record does not report the analysis plan, missing-data handling, randomization details, or original sample-size rationale. Those absences do not invalidate the posted comparisons, but they limit reproducibility and assessment of bias. The trial is a useful case for separating observed results from what can be inferred about methods that are not documented.

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 outcome population is narrowly described: participants undergoing elective laparoscopic cholecystectomy. The registry record does not provide participant characteristics or eligibility details, so it is not possible to assess how well the enrolled group represents other surgical populations. The comparison concerns two cord arrangements in this setting and should not automatically be extended to other operations or technical configurations.

The primary endpoint is histologic evidence at the umbilical port site, assessed by biopsy at 1 day. The secondary endpoint concerns the epigastric site. This limited set of locations and timing does not describe longer-term outcomes or all possible consequences of electrosurgery. The registry record does not report histologic grading criteria, assessor procedures, or how ambiguous findings were classified.

Each group included 42 participants in the posted outcome results. The primary confidence interval shows uncertainty in the estimated difference, and the record does not report a target precision or original sample-size justification. Missing outcome data, participant flow, adherence to the assigned cord arrangement, and analysis-population definitions are not reported.

Although the trial is described as randomized and single-masked, the registry record does not specify the sequence-generation method, concealment, or which parties were masked. It also does not report the statistical analysis plan, multiplicity handling, or adjustment strategy. The unadjusted secondary result merits particular caution. These limitations restrict evaluation of generalizability, implementation, and the robustness of inference beyond the posted summary results.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Bundling and Unbundling the Laparoscopic Electrosurgery Cord With the Camera Cord — NCT01707095.
• Registry record last updated 2014-07-17; status last verified 2014-07.
• Results first posted 2014-06-27.
• 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

The registry record describes a completed randomized, controlled, single-masked, parallel-group trial of bundling versus separating camera and active electrode cords during laparoscopic cholecystectomy. Enrollment is listed as 84, with 42 participants in each group in the posted primary outcome results. The sponsor is the University of Colorado, Denver; the trial start is listed as 2012-09 and primary completion as 2014-01.

The primary outcome is histologic thermal injury at the umbilical port site at 1 day. The posted comparison has a negative risk difference for separated versus bundled cords, with a confidence interval excluding zero and an unadjusted p-value of 0.016. A secondary histologic burn outcome at the epigastric port site is also listed, but its result is less definitive and should be interpreted separately.

Details of the original sample-size rationale, analysis plan, missing-data handling, and multiplicity strategy are not reported in the registry record. The findings describe the recorded group comparison and should be understood within those reporting limits.