Skin Surface and Intradermal Temperature Responses to Heat Stress: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Skin Surface and Intradermal Temperature Responses to Heat Stress (NCT06593067), a non-randomized na study. The primary outcome is Skin Temperature With Fan Only.

2. Clinical Question

The study asks how skin temperature measured at the surface and within the skin responds to heat stress under different cooling conditions. Its stated purpose is to compare those responses with and without evaporative and convective cooling. The primary endpoint focuses on the fan-only condition, measuring skin temperature 40 minutes into the heat intervention.

The question concerns measurement as well as physiology: temperature is assessed at different skin depths, and the record also describes surface measurements using different probe types. These distinctions matter when interpreting any comparison because the measurement location and instrument form part of what is being observed. The registry record does not report a detailed hypothesis, a planned contrast among conditions, or a numerical estimate of the temperature response.

3. Trial Design

The registry record identifies the study as completed, non-randomized, and single-group, with no masking. Enrollment is listed as 27. The sponsor is University of Texas Southwestern Medical Center. The listed study start is 2024-10-01, and primary completion is listed as 2025-11-13. The phase is recorded as not applicable.

Four intervention entries appear in the record: Control, Fan, Fan and Water Spray, and Water Spray. The primary endpoint is specifically titled Skin Temperature With Fan Only. Separately, the outcome descriptions identify measurement groups for a needle placed in the intradermal skin layer, the same type of needle used on the surface, and a thermistor on the surface. These descriptions distinguish measurement arrangements; they do not establish that each is a separate treatment arm or a randomized group.

The stated purpose is to compare surface and intradermal skin temperature responses to heat stress with and without evaporative and convective cooling. The registry record does not report how the cooling conditions were ordered or assigned, whether participants experienced more than one condition, the duration of all conditions, or the procedures used to control heat exposure. It also does not report whether measurements were repeated within participants or how the measurement groups relate to the listed interventions.

Because allocation is non-randomized and the model is single-group, this record does not describe a randomized, parallel-group efficacy trial. A causal interpretation of differences between cooling conditions would require details about assignment, order, measurement, and analysis that are not reported in the registry record. The analysis count is listed as 0. Numerical primary outcome results and inferential analyses are not reported in the registry record, so the design information alone cannot establish the size or precision of a temperature response.

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 Skin Temperature With Fan Only, measured over 40 minutes into the heat intervention..

The primary endpoint is mean skin temperature, measured in degrees Centigrade 40 minutes into the heat intervention during fan cooling. The description specifies small temperature-sensitive electrodes attached to the skin surface and intradermal layer. The endpoint is therefore a continuous measurement, and the registry record identifies the intended summary as a mean with standard deviation.

Temperature is used to describe the response at the measurement locations under the stated heat and cooling condition. Measuring at the surface and within the skin can address whether the recorded response differs by depth; surface probes of different types can also be relevant because instruments and placement may affect what a measurement represents. These are general measurement considerations, not reported findings from this study.

The record does not report the observed mean, standard deviation, number of measurements contributing to the endpoint, or a confidence interval. It therefore does not establish the magnitude or precision of the fan-only temperature estimate. Nor does the endpoint description by itself provide a comparison with another cooling condition. A mean describes the central value of observations, while the standard deviation describes their spread; neither is a substitute for a reported estimate and its uncertainty.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical interpretation begins with the type of endpoint. Skin temperature is continuous: it can take values across a measurement scale rather than being limited to a set of categories. The registry record specifies a mean and standard deviation as the summary format. In general, the mean describes the center of a set of measurements, and the standard deviation describes how dispersed the measurements are around that center. These summaries answer different questions and should be considered together when both are available. The actual values are not reported in the registry record.

What does a mean estimate describe?

In general, a mean is a summary of the measurements included in its calculation. Its interpretation depends on the measurement procedure, the people or observations included, and the time at which measurement occurred. Here, the endpoint description sets the time at 40 minutes into the heat intervention and identifies the fan cooling modality, with electrodes attached at surface and intradermal locations. The record does not report how many measurements contributed to the mean, whether observations were repeated, or whether the mean was calculated separately by measurement location.

A mean alone does not show the full distribution of measurements. Two sets of observations can have the same mean but different degrees of spread. The standard deviation helps describe that spread, but it is not an uncertainty interval for the mean. A confidence interval, when calculated and reported, addresses uncertainty in an estimate under a specified statistical model. Neither a standard deviation nor a confidence interval for the primary endpoint is reported in the registry record.

Why does measurement location matter?

The record distinguishes an intradermal needle, a needle of the same type placed on the skin surface, and a standard surface thermistor. In general, measurement location and instrument can influence the reading and the interpretation of a measured quantity. Comparing measurements across locations or devices requires an analysis that accounts for how the observations were collected and whether they are paired or independent. The registry record does not report the relevant pairing structure, calibration details, or a statistical comparison among these measurement arrangements.

The primary endpoint description refers to electrodes at the surface and intradermal layer, while the arm descriptions also distinguish probe arrangements. This wording identifies intended measurement features but does not provide enough information to reconstruct a data structure or analysis model. The analysis count is 0, and a statistical model for the endpoint is not reported in the registry record.

What does non-randomized, single-group mean for interpretation?

These design labels indicate that the record does not describe a randomized, parallel-arm comparison. In general, random assignment can help balance measured and unmeasured factors between groups, while non-random assignment does not have that same design protection. A single-group label also does not, by itself, say whether participants underwent multiple conditions or how those conditions were ordered. The registry record does not report assignment procedures, condition sequence, washout periods, or whether each participant contributed measurements under multiple cooling modalities.

As a general matter, comparisons made under different conditions can be influenced by time, order, exposure, or measurement differences. If observations are repeated within the same participant, their dependence also matters: treating correlated observations as if they were independent can misstate uncertainty. If observations come from separate participants, other sources of between-person variation may matter. Which situation applies is not reported in the registry record, so no specific model or adjustment can be attributed to the study.

How should uncertainty and significance be read?

In general, statistical inference combines an estimate with assumptions about variability and how observations were generated. A confidence interval conveys a range of values compatible with the data and model at a stated confidence level. A p-value is tied to a null hypothesis and a test procedure; it is not the probability that a hypothesis is true, and it does not measure effect size. The registry record reports no confidence interval, p-value, test statistic, or inferential analysis for the primary endpoint. There is therefore no basis in this record for judging statistical significance or precision.

Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes. In such cases, a model that understates variability may produce overly narrow uncertainty intervals or misleading tests. This issue is especially relevant when selecting models for count or clustered data; it should not be assumed to apply to this continuous temperature endpoint without evidence. The registry record does not report a model, residual diagnostics, or an over-dispersion assessment.

What do planning calculations mean?

Sample-size calculations are prospective planning tools: they estimate the amount of information that may be needed to detect a specified effect under stated assumptions. The registry record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such illustrations are not the study's observed power. Observed power is not a substitute for interpreting an estimate and its uncertainty, and a planning calculation does not establish that the original study design used those assumptions.

The assumptions describe a hypothetical two-arm allocation, while this study is classified as non-randomized and single-group. Any planning figures should therefore be understood as illustrations rather than a description of the actual study design. No sample-size justification or prospective calculation for the trial's own design is reported in the registry record. The record does not provide the numerical planning estimates in the registry record for this analysis.

For all these methods, interpretation depends on the actual observations and analysis plan. Since the registry record reports no numerical temperature results and no analyses, statistical concepts can clarify what the specified endpoint would mean, but they cannot fill in the missing estimate or establish a result.

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("Intradermal Skin Temperature Needle in Intradermal", "Intradermal Skin Temperature Needle on Skin Surfac", "Skin Temperature Thermistor on Skin Surface")
n   <- c(9, 9, 9)
m   <- c(36.9, 37.8, 37.4)
sp  <- c(0.5, 0.7, 0.5)
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  Intradermal Skin Temperature Needle in Intradermal  9  36.900  0.500  36.516  37.284
CARM  Intradermal Skin Temperature Needle on Skin Surfac  9  37.800  0.700  37.262  38.338
CARM  Skin Temperature Thermistor on Skin Surface  9  37.400  0.500  37.016  37.784

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists four outcome measures and an analysis count of 0. It does not report a multiplicity adjustment, a hierarchy of outcomes, or a prespecified procedure for choosing among multiple comparisons. When several outcomes or contrasts are tested, the chance of at least one false-positive finding can increase if each is tested separately at the same threshold. In general, multiplicity procedures address this issue, but the record does not state whether any such procedure was planned or used.

The primary endpoint is identified as skin temperature with fan only, measured 40 minutes into the heat intervention. The record does not report how this endpoint relates analytically to the other outcome measures, whether there was a formal primary analysis population, or whether other comparisons were exploratory. No result-level analysis population is reported in the registry record.

Missing-data methods and the extent of missing outcome data are not reported in the registry record. The record also does not report participant flow, exclusions from analyses, or how incomplete measurements would be handled. In general, missing observations can affect an estimate when the likelihood of missingness is related to participant characteristics or outcomes; the appropriate approach depends on the reason and pattern of missingness. No assumption or method can be attributed to this study from the available record.

The registry record does not report whether interim analyses were planned or conducted, nor does it report stopping rules or adjustments for repeated looks at accumulating data. These omissions do not establish that such procedures did or did not occur; they mean that they are not reported in the registry record.

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.

The safety record gives three measurement-group entries: an intradermal needle in the intradermal skin layer, the same type of needle on the skin surface, and a thermistor on the skin surface. For each listed group, the record reports 9 at risk, 0 affected by serious adverse events, 0 affected by other adverse events, and 0 deaths. These are the reported counts for each entry, not a comparative estimate of risk between cooling conditions.

In general, an at-risk count describes the group monitored for an event, while an affected count describes participants recorded as experiencing it. The registry record does not clarify further whether event collection covered all possible adverse events, how events were defined, or how the safety groups correspond to the cooling interventions. It also does not report event timing or a narrative account of monitoring.

Zero recorded events in these entries means that no affected participants or deaths are listed in the registry record for those categories. It should not be interpreted as evidence that an event is impossible or that all potential harms were assessed. These descriptive counts do not establish comparative safety, and no safety analysis is reported in the registry record.

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

The record establishes that a completed, non-randomized, single-group study was intended to examine skin-surface and intradermal temperature responses to heat stress, including cooling conditions with and without evaporative and convective cooling. It identifies a fan-only primary temperature endpoint at 40 minutes into the heat intervention and specifies mean and standard deviation as the summary format.

It does not report the observed endpoint values. Without a mean, a measure of spread, or an uncertainty interval, the magnitude and precision of the temperature response cannot be determined from the registry record. The record also provides no inferential analysis, so it cannot establish statistical significance or support a numerical comparison among cooling conditions.

The design labels do not support treating the listed conditions as randomized comparison groups. Details about condition assignment and order, repeated measurement, and the relationship between intervention entries and measurement groups are not reported in the registry record. Those details would be important for determining whether contrasts are within-participant or between-participant and for selecting an appropriate analysis.

In general, a specified temperature measurement can be useful for describing a physiological response under defined conditions. It does not, by itself, establish that a cooling approach causes a change, that a measured difference is clinically important, or that a response generalizes beyond the study conditions and participants. The registry record does not report enough information to assess those questions.

The safety entries report zero serious adverse events, zero other affected participants, and zero deaths in each listed measurement group. Those counts are limited descriptive information and do not constitute a full comparative safety assessment. Overall, the record documents the study objective and endpoint specification, but does not provide outcome results from which to draw a conclusion about the temperature response.

14. Why This Trial Matters Statistically

This study raises a useful statistical question about what is being measured: temperature at the skin surface and temperature within the skin are related but distinct measurement targets. The registry record also distinguishes a needle used at two locations from a thermistor used at the surface. As a general principle, measurement location and instrument should be considered when interpreting differences, because a numerical contrast may reflect both the underlying response and the way it was measured.

The record also highlights the importance of matching the analysis to the design. It classifies the study as non-randomized and single-group, while listing multiple cooling conditions. That combination makes it especially important to know how conditions were assigned, ordered, and measured before interpreting any contrast. Those procedural and analysis details are not reported in the registry record, and no analysis is listed.

A clearly defined time point is another useful feature of the endpoint description: the primary measurement is specified at 40 minutes into the heat intervention. Fixing a measurement time can help make an endpoint interpretable, but it does not replace reporting the estimate, variability, and uncertainty. Those numerical results are not reported in the registry record.

Finally, the record illustrates the distinction between study completion and availability of interpretable results. The study status is completed, but the record does not report the primary temperature estimate or an analysis. Statistical interpretation depends not only on a stated objective and design, but on transparent reporting of the observations and methods used to summarize and compare them. Without those results, the study's intended measurement can be described, but its observed temperature response cannot be quantified from the record.

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 record is that numerical primary outcome results are not reported in the registry record. The mean and standard deviation specified for the continuous endpoint are absent, as are a confidence interval, a treatment contrast, and inferential results. The analysis count is 0, which leaves no reported model or test to evaluate.

Important design details are also not reported in the registry record. These include how participants were assigned to or experienced the cooling conditions, the order and timing of conditions beyond the primary endpoint time point, and how the intervention entries correspond to the measurement groups. Without those details, it is not possible to determine the appropriate comparison structure or assess whether observations may be paired or repeated.

The record does not report eligibility criteria, participant characteristics, outcome-specific denominators, measurement calibration, missing-data handling, or an analysis population. It therefore offers limited information for judging representativeness, measurement precision, completeness, and potential sources of bias. A sample-size justification for the trial's own design is not reported in the registry record.

The safety information is limited to the listed counts for three measurement groups. Broader safety collection methods and definitions are not reported in the registry record, so the zero affected counts cannot serve as a comprehensive assessment of safety. These limitations concern what can be interpreted from the record; they do not establish that the underlying procedures or analyses were absent.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Skin Surface and Intradermal Temperature Responses to Heat Stress — NCT06593067.
• Registry record last updated 2026-08-14; status last verified 2026-08.
• Results first posted 2026-08-14.
• 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 titled Skin Surface and Intradermal Temperature Responses to Heat Stress, sponsored by University of Texas Southwestern Medical Center. It lists hyperthermia as the condition, enrollment of 27, a non-randomized allocation, no masking, and a single-group model. The stated purpose is to compare surface and intradermal skin temperature responses to heat stress with and without evaporative and convective cooling.

The primary endpoint is mean skin temperature in degrees Centigrade, measured 40 minutes into the heat intervention during fan cooling. The record describes surface and intradermal electrode measurements and specifies standard deviation as the dispersion measure. It lists four outcome measures and an analysis count of 0.

Numerical primary outcome results, inferential analyses, and a detailed statistical plan are not reported in the registry record. The safety entries list zero serious events, zero other affected participants, and zero deaths in each of three measurement groups. The design and outcome descriptions define the intended study question, but the record does not provide results sufficient to quantify the temperature response.