Body Temperature in Persons With Tetraplegia When Exposed to Heat: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Body Temperature in Persons With Tetraplegia When Exposed to Heat (NCT01890915), a registered phase not stated study. The primary outcome is Core Body Temperature.

2. Clinical Question

The study also lists cognitive performance, measured with Stroop Interference T-scores, as a secondary outcome. The brief summary frames the work as preliminary and as informing future study of temperature regulation and cognitive performance. That rationale does not establish that the temperature exposure caused any particular physiological or cognitive response. The record describes what the investigators intended to compare, but does not report effect estimates or uncertainty for the primary outcome.

3. Trial Design

The registry lists this as a completed study sponsored by James J. Peters Veterans Affairs Medical Center. The recorded start is 2013-05, and primary completion is recorded as 2015-10. The registry lists enrollment as 21. Separately, the brief summary describes a proposed one-visit study of 20 subjects, with 10 people with tetraplegia and 10 controls. Those are different enrollment figures in the record; the reason for the difference is not reported in the registry record.

The study is described as heat exposure rather than as a randomized treatment comparison. Allocation is not stated. The registry cautions that the arms are not a like-for-like control comparison, so group differences should not automatically be interpreted as causal effects of tetraplegia or of heat exposure. The control group is described as age- and gender-matched, but details about how matching was conducted or accounted for in analysis are not reported in the registry record.

The planned exposure is described in two ways. The brief summary says participants would be exposed to 81°F for 40 minutes and then 95° F for up to 2 hours. The primary outcome description instead refers to a seated baseline at 79 degrees F for 30 minutes followed by 95 degrees F for up to 2 hours. The record does not explain the difference between these descriptions. The primary outcome timeframe is 2 hours.

Physiological and psychological processes were to be monitored for safety and to compare responses to hot ambient temperatures. The record lists three outcome measures and three analyses, but does not provide the analysis methods or results for them. Further details about visit procedures, the statistical plan, and the conduct of follow-up 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

Reasons for not completing this period:

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 Core Body Temperature, measured over 2 hours.

The primary endpoint is core body temperature, reported as percent change, with the outcome parameter described as the mean and dispersion described as the standard deviation. Its timeframe is 2 hours. The endpoint description concerns change in core temperature in the seated position, from a stated baseline condition to exposure at 95 degrees F for up to 2 hours.

Core temperature is used to describe the body's internal temperature response during heat exposure. Comparing the mean percent change between the tetraplegia and able-bodied groups addresses the registered hypothesis about whether the temperature response differs between those groups. The standard deviation describes variation among measurements or participants around the group mean; it is not a measure of how precisely the mean itself is estimated.

The registry's exposure descriptions do not fully agree: the brief summary gives 81°F for 40 minutes before the hotter exposure, whereas the primary endpoint description gives 79 degrees F for 30 minutes. Both describe subsequent exposure to 95 degrees F for up to 2 hours. The record does not clarify which baseline description governed the endpoint analysis.

No group means, percent changes, standard deviations, between-group estimate, confidence interval, or test result for the primary endpoint are reported in the registry record. Consequently, the endpoint definition can be described, but the direction, magnitude, and precision of the observed temperature response cannot be assessed from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean describe?

The primary outcome is a continuous measure, and the registry specifies a mean as its summary parameter. A mean gives a central summary of the recorded values for a group. It can make group-level comparison straightforward, but it does not show whether individual observations cluster closely around that value or vary widely. The registry names standard deviation as the measure of dispersion. Standard deviation describes spread around the mean; it should not be read as the uncertainty in the estimated mean or as a confidence interval for the between-group difference.

The endpoint is described as percent change in core body temperature. The registry does not report the calculation details or the resulting values. Without the group summaries and analysis results, a reader cannot determine the size or direction of the mean change, how variable the measurements were, or whether the groups differed with useful precision.

What would a between-group estimate show?

A between-group estimate expresses the contrast in the outcome between the groups under a specified analysis. Its interpretation depends on the precise definition of the outcome, the observations included, and how the study design is handled. A confidence interval communicates uncertainty around that estimate. In general, it shows which values remain reasonably compatible with the observed data and the statistical model. It does not guarantee that the true effect lies within the interval, and it does not resolve bias from a design or measurement problem.

No between-group estimate or confidence interval for core temperature is reported in the registry record. A p-value is also not reported for the primary endpoint. A p-value, in general, describes how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the analysis assumptions. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. Without the actual outcome analysis, no inferential conclusion can be drawn from the registered hypothesis alone.

How does the design affect interpretation?

The registry describes heat exposure and two groups, but does not state that participants were randomly allocated. It also cautions that the arms are not a like-for-like control comparison. In general, random allocation can help balance measured and unmeasured characteristics between treatment groups, while nonrandomized group comparisons can remain affected by differences that precede the exposure. Age and gender matching is described for controls, but the matching procedure and its treatment in analysis are not reported. Matching does not, by itself, ensure comparability on other characteristics.

The record gives two different descriptions of the initial temperature condition and duration. This matters statistically because the definition of the exposure and baseline condition determines what change the endpoint represents. The registry does not explain the difference, so it is not possible to establish from the record which description corresponds to the analyzed endpoint.

What do the planning assumptions mean?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It says the target effect is a stated fraction of the observed effect. Such calculations illustrate the number of participants per arm that might be needed under those assumptions to detect a selected effect at a selected power target. They are planning illustrations, not evidence that the completed study had that power and not a substitute for its observed effect estimate.

These calculations depend on the assumed effect, variability, allocation, and statistical model. If the observed effect used as a planning reference is uncertain, the resulting illustration is uncertain too. The numerical planning outputs are not reported in the registry record. The record does not report the trial's own sample-size justification, so the planning illustration should not be treated as the original design rationale.

Why can variability affect a model?

General statistical explanation: when data vary more than a model assumes, the model may understate uncertainty. Over-dispersion is one name for variation that exceeds the level expected under a chosen model. It can make standard errors too small and confidence intervals too narrow if not addressed. The registry identifies a continuous mean outcome with standard deviation, but does not report an over-dispersion assessment or a model for the primary outcome. There is no basis in the record to say whether this issue arose or how it was handled.

Overall, the registry identifies the outcome type and some planning assumptions, but does not report enough analysis detail or outcome results to reproduce or evaluate the primary comparison. The analysis population, missing-data approach, covariate adjustment, and handling of repeated measurements are not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Tetraplegia", "Control")
n   <- c(8, 9)
m   <- c(2.04, -0.05)
sp  <- c(0.49, 0.61)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Tetraplegia  8  2.040  0.490  1.630  2.450
CARM  Control  9  -0.050  0.610  -0.519  0.419

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and three analyses. It identifies core body temperature as the primary outcome and lists cognitive performance measured with Stroop Interference T-scores as a secondary outcome. The other outcome measures are not identified in the available record. The statistical plan for prioritizing outcomes or controlling the chance of false-positive findings across multiple comparisons is not reported in the registry record.

Multiplicity arises when several outcomes, comparisons, time points, or analyses are examined. In general, conducting more tests can increase the chance that at least one result appears statistically notable by chance. Methods such as prespecifying a primary endpoint, adjusting significance thresholds, or using a hierarchical testing plan can address different multiplicity concerns. The registry record does not say whether any such method was planned or used. The listed count of analyses alone does not establish how many statistical tests were performed or whether adjustment was appropriate.

Missing-data handling is also not reported in the registry record. The record does not state how many participants contributed primary outcome observations, whether any measurements were missing, why data might have been unavailable, or whether any imputation or sensitivity analysis was used. Without those details, the effect of incomplete data on the estimates cannot be evaluated.

The analysis populations are not described. It is not reported whether analyses included all enrolled participants, only those completing exposure, or another defined group. The enrollment figure and the proposed group sizes in the brief summary do not establish the analysis denominators. These omissions limit assessment of both the statistical procedures and the potential for selection due to incomplete observations.

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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: autonomic dysreflexia (9.1%).

The registry lists serious adverse events affecting 1 person in the tetraplegia group, with 11 at risk, and 0 people in the control group, with 10 at risk. The listed top serious-event term is autonomic dysreflexia, at 9.1%. The record also lists 0 other adverse events among 11 at risk in the tetraplegia group and 0 among 10 at risk in the control group.

These figures describe events recorded in the registry; they do not, on their own, establish whether an event was caused by the exposure. The groups were not described as a like-for-like control comparison, and the record does not provide further event narratives, timing, severity details beyond the serious-event classification, or an attribution assessment. The top-term listing does not provide enough information to establish how the term relates to all event records beyond its registry label and percentage.

Deaths are listed as null for both groups. A null entry is not the same as a reported zero, so deaths are not reported in the registry record. The adverse-event counts should therefore be read as the recorded figures with the listed at-risk group sizes, alongside the limits of the available reporting, rather than as a complete characterization of safety.

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

The registry record establishes that this completed study was designed to examine core body temperature during heat exposure in people with tetraplegia and able-bodied controls. It describes the primary outcome as mean percent change in core temperature over a timeframe of 2 hours, and states a hypothesis about greater temperature increase in the tetraplegia group. It also identifies cognitive performance as a secondary outcome and provides a limited summary of adverse events.

The record does not report primary outcome estimates, group variability, a between-group comparison, confidence intervals, or p-values. It therefore cannot establish the observed direction or magnitude of temperature change, how precisely the response was estimated, or whether the groups differed in the analyzed data. The registered hypothesis is a proposed question, not a result.

The study design also limits causal interpretation. Allocation is not stated, and the registry cautions that the arms are not a like-for-like control comparison. Age and gender matching is described, but the implementation and analysis of matching are not reported. Group comparisons in this setting should not be treated as proof that group status caused any observed difference.

The record gives different descriptions of the initial exposure condition, and it does not explain the difference. It also does not report missing-data procedures, analysis populations, or the statistical plan for the listed outcomes and analyses. These gaps constrain interpretation independently of the absence of outcome estimates.

Accordingly, the record supports a description of the intended study question and the recorded adverse-event figures, but not a conclusion about whether core temperature changed by a particular amount or whether a difference between groups was statistically or clinically meaningful. The absence of reported estimates is not evidence that there was no effect; it means the effect cannot be evaluated from the registry record.

14. Why This Trial Matters Statistically

This study illustrates why a registered hypothesis and an outcome definition are not enough to assess a clinical comparison. The primary outcome is described as mean percent change in core body temperature, but interpretation requires the group estimates, their variability, and an uncertainty measure for the contrast. Without those results, readers cannot distinguish a small, precisely estimated response from a large but uncertain one, or determine whether the results are compatible with the registered hypothesis.

It also demonstrates the importance of matching the analysis to the design. The registry describes a tetraplegia group and an age- and gender-matched able-bodied control group, while cautioning that the arms are not a like-for-like control comparison. Matching may address selected characteristics, but it does not ensure equivalence on all relevant factors. Allocation and the treatment of matching in analysis are not reported. Those design details matter when interpreting group contrasts as descriptive associations rather than causal effects.

Outcome definitions and protocol descriptions need to be clear enough for readers to know what was measured. Here, the initial exposure condition is described differently in the brief summary and the primary endpoint description. The record does not clarify the difference. This makes it harder to connect a result, if reported elsewhere, to a clearly specified baseline and exposure sequence.

Finally, the record lists multiple outcome measures and analyses but does not report multiplicity procedures, missing-data handling, or analysis populations. These are not merely technical details: they affect how confidently estimates can be interpreted and how much influence selective analysis or incomplete observations might have. The study's statistical value cannot be judged from design intent alone; transparent reporting of estimates, uncertainty, and analytic decisions is essential.

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 primary limitation for interpretation is that the registry record does not report results for core body temperature. It provides no group means, standard deviations, effect estimate, confidence interval, or test result. The direction, size, and precision of the primary outcome therefore cannot be assessed. The same record does not provide results for the listed cognitive outcome.

The group comparison has design limitations documented in the registry itself. Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. Although controls are described as age- and gender-matched, how matching was performed and addressed in analysis is not reported. Other group characteristics and any adjustment for them are also not reported in the registry record.

Exposure conditions are not described consistently. The brief summary specifies 81°F for 40 minutes before 95° F for up to 2 hours, while the primary outcome description specifies 79 degrees F for 30 minutes before exposure to 95 degrees F for up to 2 hours. The record does not clarify which description applies to the analyzed endpoint or why they differ.

The registry lists enrollment as 21, while the brief summary describes a proposed study of 20 subjects. The record does not explain the difference or identify the analysis population. It does not report whether primary outcome measurements were missing, how missing data were handled, or whether sensitivity analyses were conducted. Details of outcome measurement, the statistical model, multiplicity procedures, and the trial's own sample-size justification are also not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Body Temperature in Persons With Tetraplegia When Exposed to Heat — NCT01890915.
• Registry record last updated 2016-03-03; status last verified 2016-02.
• Results first posted 2016-03-03.
• 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

NCT01890915 is a completed heat-exposure study sponsored by James J. Peters Veterans Affairs Medical Center. The registry lists enrollment as 21 and describes a comparison between people with tetraplegia and able-bodied controls. The primary endpoint is mean percent change in core body temperature over 2 hours; cognitive performance measured with Stroop Interference T-scores is listed as a secondary outcome.

The registry describes different initial exposure conditions in its brief summary and primary endpoint description. Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. It lists serious adverse events affecting 1 person in the tetraplegia group and 0 in controls. Primary outcome estimates and key analysis details are not reported in the registry record, so the temperature comparison's magnitude and precision cannot be evaluated.