This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Heart Rate Variability in Trauma Patients (NCT00795535), a registered phase not stated study. The primary outcome is Base Deficit </= -6.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00795535 |
| Phase | Phase not stated |
| Condition | Trauma |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 95 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Miami |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns trauma patients assessed in prehospital and hospital settings. The primary endpoint population is described as 75 patients with complete heart rate variability and trauma registry data. The registry record lists enrollment of 95.
Intervention
This is not a treatment intervention study. The investigators prospectively measured electrocardiograms and derived heart rate variability measures. The stated purpose was to develop a triage tool based on heart rate variability.
Comparator
No randomized comparator is described. The registry record does not state an allocation method, and the listed trauma-patient group is not a like-for-like control comparison. The proposed work instead relates heart rate variability to clinical and physiological measures.
Primary question
The registered primary endpoint counts participants with a base deficit at or below -6 upon hospital arrival. The broader research question is whether reduced heart rate variability in the field correlates with poor outcomes, and whether considering other factors can improve its performance as a screening measure. The registry record does not report the endpoint count or an estimated relationship between heart rate variability and this endpoint.
3. Trial Design
The registry record describes a prospective observational study of heart rate variability in trauma patients. Electrocardiograms were to be measured in two settings: prehospital, including in the field and during helicopter transport, and in the hospital. Heart rate variability was to be derived from the electrocardiogram signal. The description also proposes relating it to other non-invasive signals, routinely measured variables, injury severity, and day of discharge.
The stated development aim was to construct an algorithm using multiple linear regression. The hypotheses concern whether reduced field heart rate variability correlates with poor outcome, whether screening specificity and efficiency can be improved by accounting for factors such as heart rate, age, gender, respiratory rate, and pulse oxygen saturation, and whether an interpretable heart rate variability index can be derived for triage or diagnosis. These are stated aims; the registry record does not provide the algorithm, its performance, or results for those hypotheses.
The primary outcome is a participant count for base deficit at or below -6 upon hospital arrival. The primary population is described as 75 patients with complete heart rate variability and trauma registry data. The registry record lists 95 participants enrolled. It does not describe randomization, an assigned intervention, or a control group. Allocation is not stated, and the listed group is not a like-for-like control comparison.
The study is marked completed. Its recorded start is 2007-05 and its primary completion is 2014-12. A detailed protocol, a sample-size justification, and a full statistical 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.
Overall Study
| Stage | Trauma Patients |
|---|---|
| STARTED | 95 |
| COMPLETED | 75 |
| NOT COMPLETED | 20 |
Reasons for not completing this period:
| Reason | Trauma Patients |
|---|---|
| incomplete data and technical problems | 20 |
Analysis population for the primary outcome, as defined in the registry: 75 patients with complete HRV and trauma registry data
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: 75 patients with complete HRV and trauma registry data
| Characteristic | Unit | Trauma Patients |
|---|---|---|
| Participants analysed | 75 | |
| Age, Continuous | years | 47 (SD 20) |
| Sex: Female, Male: Female | Participants | 28 |
| Sex: Female, Male: Male | Participants | 47 |
6. Primary Endpoint
The registry lists the primary outcome as Base Deficit </= -6, measured over Upon arrival to the hospital.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with a base deficit at or below -6 upon arrival at the hospital. It is a binary classification at the participant level: each person either meets the stated threshold or does not. The registry record describes base deficit as an indicator of volume deficit and resuscitation, and states that a value at or below -6 signifies volume deficit and the need for volume resuscitation with fluids, blood or blood products, alone or in combination.
The record describes base deficit as the absolute difference of the base deficit from its normal range (-2 to 2). The endpoint therefore captures a threshold-defined finding at hospital arrival, rather than a continuous change over time or a later clinical outcome. The endpoint description does not state that this count itself measures the accuracy of heart rate variability as a triage tool. That would require results relating heart rate variability to the endpoint, which are not reported in the registry record.
The number of participants meeting the threshold is not reported in the registry record. Consequently, the posted endpoint information defines what was counted and when, but does not establish how often it occurred in the analysis population.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically oriented measurement question: whether heart rate variability can contribute to triage assessment in trauma patients. It describes prospective electrocardiogram measurement in prehospital and hospital settings and proposes examining relationships with other signals, routinely measured variables, injury severity, and day of discharge. Those aims do not, on their own, establish that heart rate variability predicts an outcome or improves a screening tool.
The registered primary endpoint is the count of participants whose base deficit was at or below -6 upon hospital arrival. The analysis population is described as 75 patients with complete heart rate variability and trauma registry data. However, the number meeting the threshold is not reported in the registry record. No effect estimate, association measure, confidence interval, or p-value for the relationship between heart rate variability and the endpoint is reported in the registry record. The precision and direction of any such relationship therefore cannot be assessed from the registry information.
The record's overall enrollment is 95, while the endpoint population is defined as 75 patients with complete data. These describe different aspects of the record. The reason the primary population is smaller, and how the remaining enrolled participants were handled, are not reported in the registry record. The difference should not be interpreted as evidence of a particular kind of exclusion or missingness without further documentation.
The registry lists one analysis and four outcome measures, but does not provide a detailed analysis plan or results for the broader hypotheses. A stated plan to use multiple linear regression to construct an algorithm does not reveal which predictors were included, how the model was fitted, or how its performance was assessed. Nor does it establish whether screening performance improved after adjustment for the listed factors.
In general, an estimate describes the size and direction of an observed association, while a confidence interval conveys its statistical uncertainty. Without a reported estimate and interval, neither the magnitude nor the precision of an association can be judged. The completed status of the study indicates its recorded status, not that every stated aim has a reported result in the registry.
9. Statistical Methods Explained
What kind of study is described?
The record describes prospective measurement rather than a randomized treatment comparison. In general, prospective observational studies collect measurements as participants are assessed and then examine how those measurements relate to outcomes or other characteristics. Such relationships can be informative, but an observational design does not by itself show that one measurement causes a later outcome. The registry record does not state an allocation method, and it does not describe a randomized comparator.
The heart rate variability measures were to be derived from electrocardiograms obtained in prehospital and hospital settings. The study description also mentions comparisons with non-invasive signals and routinely measured variables. It does not specify the precise heart rate variability measures, measurement windows, or procedures for combining measurements across settings. Those details are not reported in the registry record.
How should the primary outcome be understood?
The primary endpoint is a binary participant-level outcome: whether a participant had a base deficit at or below -6 upon hospital arrival. The registry record reports this as a number of participants, rather than as a mean, rate of change, or time-to-event measure. In general, binary outcomes reduce a measurement to whether a defined condition is present. This can make a result easier to interpret, but it also means that information about values on either side of the threshold is not represented by the count alone.
The record describes the threshold as an indicator of volume deficit and resuscitation. The count for this endpoint is not reported in the registry record. Without that count or a comparison of endpoint status across heart rate variability values, the primary endpoint definition cannot establish the strength of an association.
What does the regression description tell us?
The study summary says an algorithm would be constructed using multiple linear regression. In general, multiple linear regression models a continuous response as a function of multiple predictors. It can be used to estimate adjusted associations, meaning associations conditional on the other variables included in the model. Its interpretation depends on the response, predictor definitions, model assumptions, and analysis choices.
The registry record does not report the algorithm, its fitted coefficients, diagnostics, or validation results. It also does not clarify how this planned regression relates to the binary primary endpoint. The mention of multiple linear regression should therefore be read as a stated development method, not as evidence that a particular model was successfully fitted or performed well. The record's hypotheses also refer to screening specificity and efficiency; no corresponding estimates are reported in the registry record.
In general, screening performance concerns how a rule classifies people relative to a defined outcome. Assessing that performance requires results that compare the rule's classifications with outcome status. Adjusting for heart rate, age, gender, respiratory rate, or pulse oxygen saturation may change estimated associations or classifications, but the direction and size of any change depend on observed data and the specified model. Those results are not reported in the registry record.
How should uncertainty and sample-size illustrations be read?
In general, a confidence interval gives a range of values compatible with the observed data under the statistical model. A narrow interval indicates greater precision than a wide interval, although neither alone determines whether a result is practically important. No confidence interval for the primary endpoint or heart rate variability association is reported in the registry record.
Planning illustrations based on an observed effect are not the same as the original trial's design justification. They describe hypothetical sample requirements under stated assumptions; they are not observed power and do not establish that the study was designed around those assumptions. The registry record does not report the study's own sample-size justification. The effect estimate underlying any planning illustration is not reported in the registry record, so the illustrations should not be treated as an independently documented protocol calculation.
In general, power is a design concept describing the probability of detecting an effect of a specified size under specified assumptions. It is not a measure of the probability that a result is true, and a post hoc power calculation does not substitute for an estimate and its uncertainty. No observed association estimate is reported in the registry record for interpreting power in relation to the primary question.
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.
| Arm | Participants | Events | Observed % | Clopper-Pearson 95% CI | Wilson 95% CI | Bayesian 95% credible interval |
|---|---|---|---|---|---|---|
| Trauma Patients | 75 | 12 | 16.0% | 8.6% to 26.3% | 9.4% to 25.9% | 9.4% to 26.0% |
R code and output
arm <- c("Trauma Patients")
n <- c(75)
events <- c(12)
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 Trauma Patients 75 12 16.0 8.6 26.3 9.4 25.9 9.4 26.011. Multiplicity, Missing Data and Analysis Populations
The registry record lists four outcome measures and one analysis, but it does not report a detailed plan for managing multiple outcomes or multiple statistical tests. In general, when many outcomes or analyses are examined, the chance of at least one apparently notable result can increase. Prespecifying a primary outcome and analysis can help clarify which result is central, but the record does not provide enough detail to determine the full testing strategy or whether any adjustment for multiplicity was planned.
The primary endpoint population is described as 75 patients with complete heart rate variability and trauma registry data. The handling of missing data is not reported in the registry record. It does not state how many measurements were missing, why data were incomplete, whether any imputation was used, or how incomplete records were treated for other outcomes. The enrollment figure of 95 and the complete-data population do not by themselves explain the data flow or the reasons for inclusion in the endpoint analysis.
In general, an analysis population should be defined in a way that matches the question and study design. Here, the registry does identify a complete-data population for the primary endpoint, but it does not describe additional analysis populations or sensitivity analyses. The exact population used for each of the other outcome measures is not reported in the registry record. This limits assessment of whether different outcomes were analyzed in comparable groups and how missingness may have affected the findings.
12. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Trauma Patients | 0 | 75 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Trauma Patients | 0 of 75 |
The registry lists a group titled “Trauma Patients” with 75 participants at risk for the serious adverse event measure and 0 affected. It also lists 75 participants at risk and 0 affected for the other adverse event measure. No serious adverse event terms are listed. These are the figures recorded for the listed group; the registry does not provide narrative details about event ascertainment or follow-up.
The two at-risk counts should not be added together: the record does not describe them as separate participant groups. The figures also do not establish that no adverse events occurred in every setting or during every period. They describe the recorded event counts and denominators for these registry entries. In general, a zero reported count means no events were entered for that measure in the listed group; it does not, by itself, establish complete event capture or explain how events were defined and monitored.
The record does not describe a randomized treatment comparison, so these figures should not be read as evidence comparing safety between assigned interventions. They are event counts for the listed trauma-patient group.
13. What the Result Does, and Does Not, Mean
The registry record establishes that a prospective study of heart rate variability in trauma patients was conducted and marked completed. It describes measurement in prehospital and hospital settings, a goal of developing a triage tool, and a primary endpoint based on base deficit at hospital arrival. It also provides an analysis population description and safety counts for the listed group.
It does not report the number of participants who met the primary endpoint threshold. It also does not report an association estimate linking heart rate variability to that endpoint, a confidence interval, or a p-value. As a result, the registry information does not establish the direction, magnitude, or precision of the relationship between heart rate variability and the primary outcome. It also does not show whether accounting for heart rate, age, gender, respiratory rate, or pulse oxygen saturation improved screening specificity or efficiency.
The stated goal of deriving an interpretable heart rate variability index is a research aim, not a reported finding. The described plan to construct an algorithm with multiple linear regression does not establish that an algorithm was completed, validated, or useful for triage. No model performance results are reported in the registry record.
In general, evidence of association and evidence of screening performance answer different questions. An association describes how measurements vary together; screening performance concerns how well a rule distinguishes outcome categories. Neither alone proves causation. The registry record does not report the results needed to evaluate either question for this study's primary endpoint.
The recorded zero adverse event counts are limited to the registry entries and denominators described. They do not supply a comparative safety assessment. The record supports describing the study's aims, endpoint definition, population description, and posted counts, but not a conclusion about clinical benefit or lack of benefit.
14. Why This Trial Matters Statistically
This study is statistically relevant because it frames heart rate variability as a candidate measurement for trauma triage, with data collection across prehospital and hospital settings. It also identifies potential related signals and clinical variables that could be considered when evaluating whether heart rate variability carries information about outcomes. These aims illustrate the distinction between collecting a physiological marker and demonstrating that it improves prediction or classification.
The registry record also makes clear why endpoint definitions matter. The primary outcome is a threshold-based count at hospital arrival, while the broader study description refers to injury severity, day of discharge, and screening characteristics. Those are not interchangeable targets. A model's meaning depends on which outcome it is intended to predict and when its predictors are measured.
In general, developing a triage algorithm requires more than fitting a regression model. Researchers need clear outcome and predictor definitions, an assessment of model fit and predictive performance, and evidence that performance holds beyond the data used to build the model. The registry record does not report those details or results. This makes it important to distinguish the stated methodological ambition from evidence that an algorithm was derived or assessed.
The incomplete reporting of endpoint results also limits statistical interpretation. Without an endpoint count or association estimate, readers cannot assess the observed relationship or its uncertainty. The record therefore illustrates that study aims and design descriptions can be informative while still leaving the central empirical question unanswered in the registered results.
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 interpreting this trial from the registry record is that the primary endpoint count is not reported. No estimate relating heart rate variability to the endpoint is reported either. The record therefore does not allow assessment of the observed association, its direction, magnitude, or precision.
The study summary describes several aims, including evaluating field heart rate variability, considering additional physiological factors, and developing an interpretable index. The registry record does not provide results for these aims, the algorithm, or its performance. It also does not specify the detailed measurement procedures, model specification, or validation approach. The planned use of multiple linear regression alone is not enough to evaluate those methodological choices.
The primary analysis population is described as 75 patients with complete heart rate variability and trauma registry data, while overall enrollment is listed as 95. The reason for this difference, the pattern of missing information, and any consequences for analysis are not reported in the registry record. No sensitivity analysis addressing incomplete data is described.
The record lists four outcome measures but does not give a complete statistical analysis plan or explain how multiple outcomes and analyses were handled. It does not report a sample-size justification. The study is not described as randomized, and the registry does not state an allocation method or identify a like-for-like control group. These features restrict interpretation of the record to its observational aims and posted descriptions; they do not support a treatment comparison.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Heart Rate Variability in Trauma Patients — NCT00795535.
- Registry record last updated 2015-02-09; status last verified 2015-02.
- Results first posted 2014-12-22.
- 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.
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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
The registry record describes a completed prospective study of heart rate variability in trauma patients, with electrocardiogram measurement planned in prehospital and hospital settings. Its stated purpose was to develop a triage tool and examine relationships between heart rate variability, other signals, routinely measured variables, injury severity, and day of discharge.
The primary endpoint is the number of participants with a base deficit at or below -6 upon hospital arrival. The endpoint population is described as 75 patients with complete heart rate variability and trauma registry data; overall enrollment is 95. The endpoint count and an estimate relating heart rate variability to it are not reported in the registry record. The record lists one analysis and four outcome measures, but does not provide a detailed statistical analysis plan, sample-size justification, or results for the stated algorithm-development aims.