Dispatcher-Activated Neighborhood Access Defibrillation and Cardiopulmonary Resuscitation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dispatcher-Activated Neighborhood Access Defibrillation and Cardiopulmonary Resuscitation (NCT02010151), a non-randomized na study. The primary outcome is Number of Participants Surviving at Hospital Discharge.

2. Clinical Question

The question concerns a system-level response to cardiac arrest: whether dispatcher activation of trained nearby responders is associated with a different discharge-survival outcome than conventional dispatcher-assisted CPR. The proposed pathway is described as alerting geographically accessible responders who could perform CPR and defibrillation. The registry also lists pre-hospital return of spontaneous circulation and good neurological recovery as secondary outcomes, but does not report their results.

The before-and-after comparison is important to interpreting the question. Because allocation is nonrandomized and the model is listed as single group, the periods should not be read as exchangeable randomized arms. Changes over time or differences in who was included could contribute to any observed contrast. The registry does not report a method for separating those influences from any association with NAD-CPR.

3. Trial Design

This completed population-based intervention trial is registered as NCT02010151. The registry lists Seoul National University Hospital as sponsor, enrollment of 3194, and an out-of-hospital cardiac arrest condition. The study start is recorded as 2015-03 and primary completion as 2017-12. The phase is marked NA.

The intervention is NAD-CPR. Dispatchers alert nearby trained neighborhood responders by cellular-phone short message service when they identify an out-of-hospital cardiac arrest. Responders within a geographically accessible area may attend to perform CPR and defibrillation. The conventional approach is dispatcher-assisted CPR: the dispatcher instructs the caller in CPR. The registry says the comparison is between the period before intervention and the intervention period.

Allocation is nonrandomized, masking is none, and the model is single group. These design labels matter because the two periods are not described as groups formed through random assignment. A before-and-after contrast can reflect differences in the intervention as well as changes in the population, emergency response, care, or recording over time. These are general design considerations, not claims that any particular change occurred in this trial. The registry does not report methods used to account for such differences.

The primary outcome is the number of participants surviving at hospital discharge. The registry gives its timeframe as discharge from the first admission from the emergency department within 2 month and says survival was checked at the hospital discharge point. It lists pre-hospital return of spontaneous circulation and good neurological recovery as secondary outcomes. The exclusion criteria, detailed participant flow, and period-specific outcome denominators are not reported in the registry record.

The registry lists no analysis entries. It does not report the statistical model, adjustment variables, hypothesis test, confidence interval procedure, or a protocol-defined sample-size justification. The planning illustration described for the posted results is based on an observed effect and assumed two-sided significance level 0.05, equal allocation, and a normal approximation; it is not the trial’s design rationale or observed power. Its assumptions also do not make the nonrandomized periods equivalent to randomized arms.

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

Analysis population for the primary outcome, as defined in the registry: Study population excluding exclusion criteria

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.

Population: in the before/after intervention period (January 2013 to April 2015, May 2015 to December 2017), Those cases without an attempted resuscitation effort, cases that were witnessed by EMS providers or those that occurred at a nursing home or medical facility were excluded. \* both arm participants are not double counted.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Surviving at Hospital Discharge, measured over discharge time from first admission from emergency department within 2 month.

The primary endpoint is the number of participants surviving at hospital discharge. It captures survival to a defined point in the hospital course, with the registry specifying that survival was checked at discharge from the first admission from the emergency department within 2 month. The registry describes comparing the survival-to-discharge rate between the before-intervention period and the intervention period, although the endpoint title itself is expressed as a participant count.

Hospital-discharge survival is a clinically interpretable outcome because it records whether participants reached discharge alive, rather than only an intermediate event during resuscitation. Counts can describe how many participants experienced the outcome, but comparison between periods also depends on knowing the number of participants assessed in each period. The registry does not report the period-specific survival counts, denominators, or rates, so the magnitude and precision of the primary contrast cannot be assessed from its outcome record.

The registry lists the outcome population as the study population excluding exclusion criteria. Those criteria are not reported in the registry record. It also does not report how discharge status was handled for participants whose status could not be established, whether any outcomes were missing, or whether the outcome was analyzed in a defined analysis population. These details affect how a count should be interpreted and how representative it is of all enrolled participants.

Pre-hospital return of spontaneous circulation and good neurological recovery are listed as secondary outcomes. They provide other outcome domains, but their definitions, assessment procedures, timeframes, and numerical results are not reported in the registry record. No claim about their relationship to hospital-discharge survival can therefore be made from the listed information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins by distinguishing an endpoint definition from an endpoint result. The registry defines the primary endpoint as the number of participants surviving at hospital discharge and describes comparison of survival-to-discharge rates across the before-intervention and intervention periods. It does not give the observed primary counts, period denominators, rates, effect estimate, confidence interval, or p-value. Without these, neither the size nor precision of the comparison can be described.

What a count can and cannot show

A count is the number of participants recorded with an outcome. To compare outcome frequency across groups or periods, the count needs to be interpreted against the number of participants eligible for assessment in each. A larger count does not by itself mean a more frequent outcome if the group sizes differ. The registry’s enrollment total is 3194, but period-specific denominators and the number with an observed discharge status are not reported in the registry record. No rates should be inferred from the enrollment total or from the adverse-event fields.

A confidence interval is a range of values compatible with the data under a specified statistical method. It communicates uncertainty around an estimated effect; it is not a guarantee that the true effect lies in that particular interval. A p-value, when reported, quantifies how unusual data at least as incompatible with a null hypothesis would be under that hypothesis and the assumed model. It does not measure the probability that the hypothesis is true, nor the clinical importance of an effect. The registry does not report a confidence interval or p-value for the primary comparison.

Why the design affects the comparison

Random allocation is one method for creating groups that are comparable on average at the start of a study. This trial is registered as nonrandomized and single group, with a comparison between a before-intervention period and an intervention period. In general, a before-and-after study may be influenced by differences between periods that are not caused by the intervention, including shifts in the people included, other care practices, or data collection. These are potential sources of confounding, not findings about what happened in this trial. The registry does not report a statistical adjustment strategy, concurrent control group, or analysis that would address period effects.

Masking is recorded as none. Masking can reduce the influence of knowledge of treatment assignment on some aspects of care or assessment, depending on the outcome. For this outcome, the registry says survival was checked at hospital discharge, but does not report further assessment procedures. The absence of masking does not by itself establish biased outcome ascertainment; it is a design feature relevant to evaluating the methods.

Planning calculations are not trial results

The registry describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It describes the target effect as a stated fraction of the observed effect. For non-time-to-event outcomes, the resulting quantities are participants per arm. These are planning assumptions, not a report of the trial’s allocation or a sample-size justification. The trial itself is recorded as nonrandomized and single group, so equal allocation between two arms is an illustration rather than a description of how participants were assigned.

Such calculations are sensitive to the effect chosen for planning and to assumptions about variability, allocation, and the statistical method. A planning count describes the sample size associated with those assumptions; it does not show that the trial had a particular probability of detecting an effect. It is not observed power. The registry does not report the original protocol’s sample-size calculation or justification, so the planning illustration should not be attributed to the trial design team.

Interpretation depends on the analysis details

The registry lists no analysis entries. It does not report whether the primary comparison used a model, whether any covariates were included, whether estimates were adjusted, or how uncertainty was calculated. It also does not report the handling of missing outcome data or a prespecified analysis population. These omissions limit reproducibility and make it impossible to assess whether reported statistical assumptions were appropriate, because no analysis result is listed.

Over-dispersion is a general issue for count models: it occurs when observed variability exceeds what a chosen model expects. If present and ignored, uncertainty estimates can be too small, making results appear more precise than they are. The primary endpoint is a count of participants, but the registry does not report use of a count model, evidence of over-dispersion, or any model diagnostics. This concept therefore explains a general consideration; it is not a claim about the trial’s data or analysis.

Finally, statistical significance and practical importance are distinct. A statistically precise estimate can still be small in magnitude, while an imprecise estimate may leave a broad range of effects compatible with the data. The registry’s missing effect estimate and uncertainty interval prevent either assessment for the primary endpoint. General statistical principles cannot substitute for the unreported trial results.

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("Conventional Dispatcher CPR", "NAD-CPR")
n      <- c(1498, 1696)
events <- c(135, 216)
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  Conventional Dispatcher CPR  1498  135  9.0  7.6  10.6  7.7  10.6  7.7  10.6
ARM  NAD-CPR  1696  216  12.7  11.2  14.4  11.2  14.4  11.2  14.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome, survival at hospital discharge, and two secondary outcomes: pre-hospital return of spontaneous circulation and good neurological recovery. It does not report results for these outcomes or describe a multiplicity strategy. Multiplicity arises when several outcomes or statistical comparisons are assessed: the more opportunities there are to find a result meeting a threshold, the more important it is to interpret the analysis plan and any adjustment method. No particular adjustment method should be assumed for this trial.

The registry records zero analysis entries. It does not report the number of prespecified hypotheses, whether there were additional exploratory analyses, whether any interim analyses were planned or conducted, or how outcome priorities were handled in analysis. Those details are not reported in the registry record. The listing of primary and secondary outcomes does not establish how many tests were actually performed.

Missing data handling is also not reported in the registry record. There is no reported count of participants with unknown discharge status, no explanation of how such cases were treated, and no sensitivity analysis described. Missingness can affect an outcome comparison if the probability of outcome ascertainment differs across periods or relates to the outcome. This is a general concern, not evidence that missing data occurred in this trial.

The outcome population is described as the study population excluding exclusion criteria, but the criteria and analysis population are not specified. The registry does not report whether all enrolled participants were included in the primary comparison or how exclusions after enrollment were handled. Without a participant flow and analysis-population definition, the relationship between enrollment and the primary endpoint population remains unclear.

12. 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 serious adverse event terms

Serious events with the highest arm-level rate: death (91.0%).

The serious adverse-event record lists a conventional dispatcher CPR group with 1498 participants at risk and 1363 deaths, and a NAD-CPR group with 1696 participants at risk and 1480 deaths. No other serious adverse events are recorded in the corresponding fields. The registry identifies death as the top serious term at 91.0%.

These entries require care in interpretation. The registry does not explain the denominator or calculation convention behind the 91.0% figure, define the safety-reporting period, or clarify how the serious adverse-event records relate to the primary survival endpoint. It also does not report whether events were judged related to an intervention. The figures should therefore be read as registry safety fields, not as evidence that NAD-CPR caused deaths or changed mortality.

The death counts are not a substitute for the missing primary endpoint results. The primary endpoint is survival at hospital discharge, while the safety entries have their own reporting labels and scope. The registry does not establish that the groups, observation periods, or definitions are identical for these two records. A comparison of the listed counts alone would not account for design differences or establish a causal effect.

In general, serious adverse-event data are interpreted alongside event definitions, exposure and follow-up periods, reporting procedures, and attribution assessments. Those details are not reported in the registry record. The absence of other entries in the listed fields should not be read as proof that no other clinical events occurred.

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

The registry establishes that a population-based NAD-CPR intervention was studied and that the planned primary question concerned survival to hospital discharge before and during implementation. It describes how nearby trained responders could be alerted and how conventional dispatcher-assisted CPR worked. It also records enrollment of 3194 and lists two secondary outcomes.

It does not establish the size or direction of the primary outcome contrast. Period-specific survival counts and rates, an effect estimate, and a measure of uncertainty are not reported in the registry record. Thus, the listed hypothesis that NAD-CPR would improve survival must not be mistaken for an observed finding. The registry’s completed status does not itself provide evidence of a particular outcome.

The design also limits causal interpretation. The trial is nonrandomized, uses a single-group model, and compares periods before and during intervention. In general, differences between periods may reflect intervention exposure, other changes over time, or both. The registry does not report adjustment methods that would help separate those explanations. Accordingly, even if a period difference were reported elsewhere, this registry record alone would not establish that NAD-CPR caused it.

The serious adverse-event fields list death counts and identify death as the top serious term at 91.0%, but their scope and relation to the primary endpoint are not fully described. They cannot be used as a stand-in for the primary survival analysis or interpreted as an intervention-caused harm. Results for the secondary outcomes are also not reported.

Statistical conclusions require both an estimated contrast and information about its uncertainty, together with a clear account of who was analyzed and how the comparison was conducted. Those elements are not reported for the primary outcome. The most defensible conclusion is that the registry records an intervention and an intended before-and-after question, while leaving the main outcome result and its precision unavailable.

14. Why This Trial Matters Statistically

This trial raises an important statistical problem: evaluating a population-level emergency response intervention when implementation occurs across time rather than through randomized allocation. The intervention depends on dispatcher recognition, communication with nearby responders, geographic access, and responder capability as described in the registry. The resulting comparison is not only about an individual treatment assignment; it is about a response system operating in a population.

That setting makes design and analysis choices especially important. A before-and-after contrast can be affected by temporal changes in the population or surrounding care. Randomization, when feasible, can help balance known and unknown factors, while careful adjustment and transparent sensitivity analyses may help address measured differences in nonrandomized studies. The registry does not report such methods, so their use cannot be assumed.

The case also illustrates why outcome definitions and denominators matter. Survival at hospital discharge is understandable, but interpretation requires knowing who was included in each period and how many had outcome data. A total enrollment count cannot answer those questions. Counts, rates, effect estimates, and uncertainty each provide different information, and none should be inferred from a different registry field.

Finally, the distinction between an intervention hypothesis and an analyzed result is essential. A completed study record and a stated hypothesis do not reveal whether the primary comparison favored either period, how large any contrast was, or how precise it was. The registry lists no analysis entries and does not report primary or secondary outcome results. This makes transparent reporting of estimates, denominators, uncertainty, and analysis methods particularly important for readers assessing a nonrandomized trial.

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 main limitation for interpretation is that the registry does not report the primary endpoint results. Period-specific survival counts and denominators, rates, effect estimates, confidence intervals, and p-values are not reported in the registry record. Without them, the primary comparison’s direction, magnitude, and precision cannot be assessed.

The study is registered as nonrandomized and single group. The described before-and-after comparison may be vulnerable in general to differences across periods, including changes in participant characteristics, emergency response, hospital care, or recording. These possibilities are not evidence that such changes occurred. The registry does not report adjustment methods, a concurrent control group, or sensitivity analyses to address them.

The exclusion criteria are not reported in the registry record, even though the primary outcome population is described as excluding those criteria. Period-specific enrollment, participant flow, analysis-population details, and the handling of missing discharge status are also not reported. These omissions prevent assessment of how the enrolled population relates to the endpoint analysis.

The record lists secondary outcomes but provides no numerical results or detailed definitions and assessment procedures for them. It also lists serious adverse-event counts without fully describing reporting scope, event attribution, or how those records correspond to the survival endpoint. No analysis entries are listed, and the registry does not report a statistical plan, multiplicity approach, interim analyses, or the original sample-size justification.

Finally, the planning illustration is based on an observed effect and stated assumptions, but it is not the trial’s design rationale or observed power. Its equal-allocation assumption does not describe the registered nonrandomized, single-group design. These limitations mean the registry record supports description of the study setup, but not a quantitative conclusion about its primary or secondary outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Dispatcher-Activated Neighborhood Access Defibrillation and Cardiopulmonary Resuscitation — NCT02010151.
• Registry record last updated 2020-03-30; status last verified 2020-03.
• Results first posted 2020-03-30.
• 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

NCT02010151 is a completed, nonrandomized, single-group population-based intervention trial sponsored by Seoul National University Hospital. The registry records enrollment of 3194, study start at 2015-03, and primary completion at 2017-12. The intervention is dispatcher-activated neighborhood access defibrillation and CPR; the comparison is described as conventional dispatcher-assisted CPR before intervention versus NAD-CPR during the intervention period.

The primary endpoint is the number of participants surviving at hospital discharge. Pre-hospital return of spontaneous circulation and good neurological recovery are listed as secondary outcomes. The registry does not report outcome estimates, analysis entries, or statistical uncertainty for these outcomes. Serious adverse-event fields list deaths in both groups, but do not establish their relationship to the primary endpoint or an intervention effect. The record therefore describes the study question and design, while leaving the principal outcome findings and their precision not reported.