The Effect of Age on the Incidence of Postoperative Residual Neuromuscular Blockade: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Age on the Incidence of Postoperative Residual Neuromuscular Blockade (NCT01545193), a registered phase not stated study. The primary outcome is Incidence of Residual Neuromuscular Blockade.

2. Clinical Question

3. Trial Design

The registry describes a comparison between two age-defined cohorts of patients undergoing surgery with general anesthesia. One cohort includes patients ages 18-50, and the other includes patients ages 70-90. The study title and stated aim focus on whether age is associated with the incidence of postoperative residual neuromuscular blockade. The registry does not describe a randomized allocation, and allocation is not stated. These cohorts therefore should not be read as randomized treatment arms or as a like-for-like control comparison.

The listed enrollment is 300. The study status is COMPLETED, with a start date of 2011-06 and a primary completion date of 2013-09. The adverse-event record lists 150 participants at risk in the age 18-50 group and 149 in the age 70-90 group. The registry does not explain how these safety denominators relate to the enrollment total or provide a participant flow accounting for the primary outcome.

The primary outcome is the incidence of residual neuromuscular blockade during the early postoperative period, up to 24 hours. Secondary outcomes listed are signs and symptoms of residual neuromuscular blockade, respiratory events potentially related to it, and PACU length of stay. The registry lists four outcome measures overall, but detailed results for these outcomes are not reported in the registry record.

The record does not report the study sites, recruitment procedures, eligibility criteria beyond the age cohorts and surgery/general anesthesia context, or the statistical analysis plan. Sample-size justification and any planned interim analyses 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 Incidence of Residual Neuromuscular Blockade, measured over Early postoperative period, up to 24 hours.

The primary endpoint counts participants whose train-of-four (TOF) ratio is < 0.9. TOF stimulation assesses responses to nerve stimulation; the registry says a TOF-Watch SX nerve stimulator and sensor will be used to quantify the ratio. A participant is counted as having the endpoint when the recorded ratio meets the stated threshold. The endpoint is assessed in the early postoperative period, up to 24 hours.

The registry describes obtaining two consecutive TOF responses and recording their average. If the measurements differ by > 10%, additional ratios may be obtained, up to a total of 4 values, with the closest two ratios averaged. This measurement procedure is intended to define the endpoint consistently from instrument readings rather than from symptoms alone. The registry lists signs and symptoms, respiratory events, and PACU length of stay as secondary outcomes, which capture other aspects of postoperative status; they are distinct from the primary count of participants crossing the TOF threshold.

For a binary endpoint, the key descriptive result is the number of participants with the event and the number assessed in each group. A group comparison can then quantify how the event frequency differs, with uncertainty described using an appropriate interval. These are general statistical concepts. The registry record does not report the primary endpoint counts, denominators for that endpoint, effect estimate, or uncertainty interval, so the comparison cannot be interpreted from the registry results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is being measured?

The primary outcome is binary at the participant level: a participant either meets the TOF threshold or does not, according to the registry's definition. For this type of outcome, a basic summary would report the number with the event and the number assessed in each cohort. A proportion expresses the event count relative to the assessed group, while a contrast compares the groups. These are general statistical descriptions; the registry record does not report the necessary primary counts or proportions.

The endpoint is not a direct measurement of age. Age defines the cohorts, while the instrument reading determines whether a participant is counted as having residual neuromuscular blockade. The registry specifies TOF ratios < 0.9 and explains how repeated readings may be averaged. The exact timing is described as the early postoperative period, up to 24 hours. The record does not provide participant-level readings or the distribution of assessment times.

How should uncertainty be understood?

A confidence interval is a range of values compatible with the data and a stated statistical procedure; it communicates the precision of an estimate. A narrow interval generally indicates greater precision than a wide interval, while an interval spanning values that imply different conclusions may leave substantial uncertainty. This is a general explanation, not a description of an interval reported for this study: no primary confidence interval is reported in the registry record.

A p-value, when used, describes how unusual data at least as incompatible with a specified null hypothesis would be under the model assumptions. It does not measure the size or clinical importance of a difference, and it does not establish that groups are otherwise comparable. No primary p-value or test is reported in the registry record. The analysis plan and any assumptions behind a statistical test are also not reported.

What can an age-cohort comparison establish?

Age is the basis for cohort membership rather than a randomized intervention. In general, random allocation can help balance both measured and unmeasured factors between groups, whereas comparisons of pre-existing groups may remain affected by differences between them. This does not establish that any particular factor differed in this study. The registry record does not describe measured covariates, adjustment, matching, or other methods for addressing possible group differences.

Consequently, even if a group contrast were available, it would describe the observed comparison and would not by itself establish that age caused the outcome difference. Interpreting the contrast would require the result, its uncertainty, and relevant design and analysis details. Those primary results and details are not reported in the registry record.

What do the planning assumptions mean?

The registry's sample-size assumptions describe planning illustrations, not the study's own design justification. They use a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect specified as a fraction of the observed effect. For non-time-to-event outcomes, the stated convention is participants per arm; time-to-event illustrations use total events. No numerical planning illustration values are reported in the registry record.

In general, a planning calculation estimates how many participants may be needed to detect a specified effect under stated assumptions. Its answer depends on the effect being targeted and on the statistical assumptions. An illustration based on an observed effect is not an observed-power calculation, and it does not show how likely the study was to detect an effect before data collection. The registry does not report its original sample-size rationale or the expected event frequency used to plan the study.

Over-dispersion is a general concern when outcome variation is greater than a model assumes; if ignored, uncertainty estimates can be too small. It is not clear that this issue applies to the endpoint or analysis in this record, because the statistical model and primary results are not reported. No model details should be inferred from the endpoint description alone.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Age 18-50", "Age 70-90")
n      <- c(150, 149)
events <- c(45, 86)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Age 18-50  150  45  30.0  22.8  38.0  23.2  37.8  23.2  37.8
ARM  Age 70-90  149  86  57.7  49.4  65.8  49.7  65.4  49.7  65.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures overall and names three secondary outcomes: signs and symptoms of residual neuromuscular blockade, respiratory events potentially related to it, and PACU length of stay. Examining multiple outcomes can raise a multiplicity question: when many hypotheses are tested, the chance of at least one nominally unusual result can increase. General approaches include prespecifying a primary outcome, adjusting tests, or interpreting secondary analyses as exploratory. The registry record does not report whether any multiplicity strategy was planned or used.

The primary outcome is identified as incidence of residual neuromuscular blockade. However, the analysis details are not reported in the registry record, and no analyses are listed. It is therefore unknown which comparison method was used, whether results were adjusted for any covariates, or how the secondary outcomes were handled. No unreported adjustment should be assumed.

Missing-data handling and analysis populations are also not reported in the registry record. The record does not say how missing or unusable TOF measurements were handled, whether participants with incomplete assessments were excluded, or whether the primary analysis included all enrolled participants. The listed enrollment is 300, while the adverse-event record gives at-risk counts of 150 and 149; the record does not explain the relation between those safety counts and the primary endpoint population.

These omissions matter because the number analyzed and the handling of unavailable measurements affect both the event estimate and its precision. Without a participant flow, endpoint-specific denominators, and missing-data rules, it is not possible to judge the extent or potential impact of missing primary outcome data.

12. 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 adverse-event record lists 150 participants at risk in the age 18-50 group and 149 in the age 70-90 group. It records zero participants affected by serious adverse events and zero affected by other adverse events in each group. These are counts in the adverse-event record; they should not be read as the primary endpoint counts or as proof that no event of any kind occurred outside the categories and reporting represented in that record.

The record does not report death counts. It also does not provide serious adverse event terms, and the detailed descriptions, ascertainment procedures, and reporting windows for adverse events are not reported in the registry record. Therefore, the zero affected counts need to be interpreted within the scope of the registry's adverse-event entries rather than as a complete account of all postoperative outcomes.

The adverse-event denominators are not identified as the primary endpoint denominators. No rates should be inferred from them, and they do not establish how many participants had TOF measurements or met the primary endpoint. The safety counts describe a separate part of the record from the primary comparison of residual neuromuscular blockade.

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

The registry record documents a completed study designed to compare a postoperative TOF-defined outcome between patients ages 18-50 and ages 70-90. It gives a measurement procedure and a primary endpoint threshold, and it lists several secondary outcomes. These details clarify what investigators intended to assess, but they are not results. The primary outcome counts and the statistical comparison are not reported in the registry record.

Accordingly, the record does not establish whether the event was more frequent in either cohort, how large a difference might have been, or how uncertain that difference was. The cohort descriptions anticipate a higher incidence in the older group and a lower incidence in the younger group, but these expectations cannot be treated as observed outcomes. A completed status does not change that distinction.

The study's age comparison also has a different interpretation from a randomized trial of an assigned treatment. Age defines the groups, and allocation is not stated. In general, comparisons between age cohorts may reflect a combination of age and other differences; the registry does not report adjustment methods that could help assess this concern. Even with a reported association, causal attribution would require caution.

The adverse-event entries show zero affected participants for the serious and other event categories in both groups, with at-risk counts listed separately. These figures do not provide the missing primary endpoint results, and the death counts are not reported in the registry record. They should not be used to infer results for TOF-defined residual blockade, symptoms, respiratory events, or PACU length of stay.

The appropriate conclusion from the registry record is therefore limited: it describes the question, cohorts, and planned measurement, but does not provide enough outcome information to evaluate the primary age-group comparison. No claim that the study found a difference, or found no difference, can be supported from the recorded results.

14. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between defining a precise measurement and reporting evidence from that measurement. The registry specifies a TOF ratio threshold, a device, and a procedure for averaging repeated readings. Those details make the intended binary endpoint understandable. Yet without the number meeting the threshold in each cohort, the endpoint definition alone cannot answer the comparative question.

The age-based design also highlights the difference between association and randomized evidence. A randomized comparison aims to make assigned groups comparable on average; an age-cohort comparison does not assign age. As a general principle, a difference between cohorts can be influenced by characteristics other than the grouping variable. Interpreting an estimate requires attention to cohort construction, measured factors, and any adjustment strategy. Those analysis details are not reported in the registry record.

The record is also a reminder that study completion and enrollment do not substitute for results. Enrollment is listed as 300, but the primary endpoint denominators, event counts, estimates, and uncertainty measures are not reported. Likewise, adverse-event counts answer a different question from the primary TOF comparison. Keeping outcome definitions and evidence separate prevents safety entries or anticipated patterns from being mistaken for the primary finding.

Finally, planning illustrations and observed results serve different purposes. Planning calculations depend on assumptions about the effect to detect and the analysis; they do not show what the study found. The registry's stated illustration assumptions therefore cannot resolve the absence of primary results. Statistically, the main lesson is that a well-defined endpoint is necessary, but a transparent account of analysis populations, estimates, and uncertainty is needed to evaluate the question.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most consequential limitation for interpreting this record is that the primary outcome results are not reported in the registry record. There are no group-specific TOF event counts or endpoint denominators, and no effect estimate, confidence interval, or p-value. As a result, neither the direction nor the precision of the age-group comparison can be evaluated.

The registry describes two cohorts but does not state how participants were allocated, and it does not describe a randomized comparison. The record also does not report covariates, adjustment methods, matching, or other analytical approaches for addressing differences between age groups. Any group contrast would therefore require cautious interpretation as an association, not as a causal effect of age.

Participant accounting is incomplete for statistical interpretation. Enrollment is listed as 300, while the adverse-event record lists 150 and 149 participants at risk in the cohorts. The record does not explain how these numbers relate to one another or to the primary endpoint analysis. Eligibility details, recruitment flow, missing TOF measurement handling, and analysis populations are not reported in the registry record.

Outcome measurement is described, but the registry does not provide the collected readings, endpoint timing distributions, or details on whether additional measurements were needed. The secondary outcomes are named, but their definitions, results, and analyses are not reported. Multiplicity handling and the analysis plan are also not reported in the registry record.

Finally, adverse-event entries list zero affected participants in the serious and other categories, but death counts and detailed event terms are not reported. Those entries cannot be interpreted as a complete account of the primary outcome or all possible postoperative events.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Effect of Age on the Incidence of Postoperative Residual Neuromuscular Blockade — NCT01545193.
• Registry record last updated 2019-09-16; status last verified 2019-09.
• Results first posted 2015-04-06.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed study of residual neuromuscular blockade after surgery and general anesthesia, comparing patients ages 18-50 with those ages 70-90. Listed enrollment is 300; the start date is 2011-06, and the primary completion date is 2013-09. The primary outcome is the number of participants with a TOF ratio < 0.9 during the early postoperative period, up to 24 hours.

The record describes TOF-Watch SX measurement and lists signs and symptoms, potentially related respiratory events, and PACU length of stay as secondary outcomes. It does not report the primary outcome counts, analyses, or effect estimate. The adverse-event entries report zero affected participants for serious and other events in both groups, while death counts are not reported in the registry record. The comparison is not described as randomized, and allocation is not stated.