Comparing Exertional Heat Illness Risk Factors Between Patients and Controls

May 19, 2023 updated by: Jo Corbett, University of Portsmouth

Comparison of Novel Putative Risk Factors for Exertional Heat Illness Between a Military Patient Cohort and Matched Control Cohort During Exercise Heat Stress

The arduous nature of military training and operations require personnel to encounter high heat load, e.g., during intense physical exertion, particularly in the heat. These conditions reduce operational effectiveness and expose personnel to a risk of incapacitation and death from exertional heat illness (EHI). The primary aim of this study is to compare putative 'chronic' EHI risk factors between a cohort who have suffered a history of EHI and a control cohort with no EHI history. The secondary aim is to examine the influence of these EHI risk factors on thermoregulation during a standard heat tolerance assessment.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Military training and operations present a risk of incapacitation and death from Exertional Heat Illness (EHI). However, widely accepted EHI risk factors are absent in almost half of all United Kingdom (UK) military EHI cases, indicating that a significant number of EHI cases in military personnel involve alternative risk factors. Risk factors for EHI can been classified along a spectrum ranging from acute (e.g. recent poor sleep) to chronic (e.g. low fitness), with the role of chronic risk factors supported by the observation that individuals who have suffered an EHI are at a substantially increased risk of subsequent EHI. The primary aim of this study is to compare putative 'chronic' EHI risk factors (e.g. composition of gastrointestinal (GI) microbiome, infection and inflammation, trait-like psychological factors) between a cohort who have suffered a history of EHI and a control cohort with no EHI history. The secondary aim is to examine the influence of these EHI risk factors on thermoregulation during a standard heat tolerance assessment.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
95

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United Kingdom
    • Hampshire
      • Portsmouth, Hampshire, United Kingdom, PO1 2UP
        • University of Portsmouth

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 40 years (Adult)

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Individuals who have experienced a recent exertional heat illness and matched controls with no previous history of exertional heat illness

Description

Inclusion Criteria:

Individuals with a history of EHI:

  • Previous EHI episode
  • Normal resting ECG
  • Male or female
  • 18 - 40 years

Control participants:

  • No previous history of EHI
  • Normal resting ECG
  • Male or female
  • 18 - 40 years

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Individuals with a history of EHI
Service personnel who have a history of EHI.
Other: Heat Tolerance Assessment
60-90 minutes exercise in hot (34 °C; 45% R.H.) conditions at 60%VO2max
Control participants without a history of EHI

Matched control participants with no history of EHI. They will be matched to the experimental group for parameters that are known to influence thermoregulatory responses to exercise heat-stress.

  1. Relative aerobic fitness (V̇O2max; ml∙kg-1∙min-1)
  2. Body mass (kg)
  3. Body surface area (m2)
  4. Age
  5. Sex
Other: Heat Tolerance Assessment
60-90 minutes exercise in hot (34 °C; 45% R.H.) conditions at 60%VO2max

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Core temperature
Time Frame: At 60 minutes (or test termination if earlier) of Heat Tolerance Assessment
Measured using a rectal thermistor.
At 60 minutes (or test termination if earlier) of Heat Tolerance Assessment
Core temperature
Time Frame: Rate of rise from 30 to 60 minutes (or test termination if earlier) of Heat Tolerance Assessment
Measured using a rectal thermistor.
Rate of rise from 30 to 60 minutes (or test termination if earlier) of Heat Tolerance Assessment
Diversity of gastrointestinal microbiota
Time Frame: Baseline
Measured in stool sample. Assessed by alpha diversity score.
Baseline
Diversity of gastrointestinal microbiota
Time Frame: Baseline
Measured in stool sample. Assessed by beta diversity score.
Baseline
Abundance of gastrointestinal microbiota
Time Frame: Baseline
Measured in stool sample. Assessed at level of phylum.
Baseline
Detection of sexually transmitted pathogens
Time Frame: Baseline
Assessed from urine sample. Measured using cobas CT/NG assays.
Baseline
Detection of respiratory pathogens
Time Frame: Baseline
Assessed from throat swab. Measured using Allplex assays.
Baseline
Detection of gastrointestinal pathogens
Time Frame: Baseline
Assessed from stool swab. Measured using Allplex.
Baseline
Circulating Interleukin 6
Time Frame: Baseline
Measured using ELISA
Baseline
Circulating Interleukin 6
Time Frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Measured using ELISA
Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating C-Reactive Protein
Time Frame: Baseline
Measured using ELISA
Baseline
Circulating C-Reactive Protein
Time Frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Measured using ELISA
Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating Claudin 3
Time Frame: Baseline
Measured using ELISA
Baseline
Circulating Claudin 3
Time Frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Measured using ELISA
Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating Zonulin
Time Frame: Baseline
Measured using ELISA
Baseline
Circulating lipopolysaccharide binding protein
Time Frame: Baseline
Measured using ELISA
Baseline
Circulating lipopolysaccharide binding protein
Time Frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Measured using ELISA
Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating intestinal fatty acid binding protein
Time Frame: Baseline
Measured using ELISA
Baseline
Circulating intestinal fatty acid binding protein
Time Frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Measured using ELISA
Post Heat Tolerance Assessment (within 15 minutes of test end)
Gastrointestinal illness symptomology questionnaire
Time Frame: Baseline
Visual analogue scale (0-10). Higher scores indicate worse symptomology
Baseline
Gastrointestinal illness symptomology questionnaire
Time Frame: Pre Heat Tolerance Assessment
Visual analogue scale (0-10). Higher scores indicate worse symptomology
Pre Heat Tolerance Assessment
Gastrointestinal illness symptomology questionnaire
Time Frame: Immediately post Heat Tolerance Assessment
Visual analogue scale (0-10). Higher scores indicate worse symptomology
Immediately post Heat Tolerance Assessment
Respiratory illness symptomology, measured by Jackson common cold questionnaire
Time Frame: Baseline
Higher scores indicate worse symptomology
Baseline
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index
Time Frame: Baseline -3 days
Higher scores indicate worse sleep
Baseline -3 days
Motivation, measured by Motivation scale
Time Frame: Baseline -3 days
Baseline -3 days
State-trait anxiety, measured by state-trait anxiety inventory form Y-2
Time Frame: Baseline -3 days
Baseline -3 days
Risk taking, measured by the risk-taking inventory
Time Frame: Baseline -3 days
Baseline -3 days
Resilience, measured by the Connor-Davidson resilience scale
Time Frame: Baseline -3 days
Baseline -3 days
Stress, measured by perceived stress scale
Time Frame: Baseline -3 days
Baseline -3 days
Mental readiness
Time Frame: Baseline
Visual analogue scale (0-100). Higher scores indicate a lower state of mental readiness.
Baseline
Stress
Time Frame: Baseline
Visual analogue scale (0-100). Higher scores indicate a greater state of stress.
Baseline

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Heat rate
Time Frame: At 5 minute intervals during the Heat Tolerance Assessment
At 5 minute intervals during the Heat Tolerance Assessment
Thermal comfort
Time Frame: At 15 minute intervals during Heat Tolerance Assessment
Modified 9 point Gagge scale. Higher scores indicate worse comfort.
At 15 minute intervals during Heat Tolerance Assessment
Thermal sensation
Time Frame: At 15 minute intervals during Heat Tolerance Assessment
Modified 9 point Gagge scale. Higher scores indicate hotter sensation
At 15 minute intervals during Heat Tolerance Assessment
Rating of Perceived Exertion
Time Frame: At 15 minute intervals during Heat Tolerance Assessment
6-20 Borg scale. Higher scores indicate higher perceived exertion
At 15 minute intervals during Heat Tolerance Assessment
Skin Temperature
Time Frame: During Heat Tolerance Assessment
Weighted mean skin temperature
During Heat Tolerance Assessment
Sweat rate
Time Frame: During Heat Tolerance Assessment
Determined from change in nude body mass during the heat tolerance assessment
During Heat Tolerance Assessment

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Body mass
Time Frame: Baseline
Baseline
Relative maximal aerobic fitness
Time Frame: Baseline
Highest value measured in ml.kg-1.min-1 during a treadmill graded exercise test.
Baseline
Urine osmolality
Time Frame: Baseline
Measured using freezing point depression
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Portsmouth

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Liverpool John Moores University
Institute of Naval Medicine (UK)
Public Health Wales (UK)
Headquarters Army Recruiting and Initial Training Command (UK)

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 1, 2022

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 6, 2023

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 6, 2023

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 3, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 21, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 31, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 22, 2023

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 19, 2023

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2023

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 209321

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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