Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12623000230651
Ethics application status
Approved
Date submitted
20/02/2023
Date registered
3/03/2023
Date last updated
19/02/2024
Date data sharing statement initially provided
3/03/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
Real-time microwearable sensor for monitoring human hydration status
Scientific title
Diagnostic performance of real-time microwearable sensor for monitoring hydration status in healthy volunteers
Secondary ID [1] 308207 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Dehydration 327958 0
Condition category
Condition code
Diet and Nutrition 325023 325023 0 0
Other diet and nutrition disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Fluid restriction followed by exercise-induced dehydration

The first visit (less than one hour) will involve several measures of hydration status (including body weight, a small quantity of blood collected via venipuncture in the arm and urine samples). You will then go about your normal daily activities for the next 24 hours but will be requested to minimise fluid intake. The following dietitian guided information will be provided:

In the 24 hours leading up to your exercise session, please minimise:
- drinks & liquids e.g. water, coffee, tea, soft drink, sports drinks, milk, juice, alcohol
- fluids that are part of a food e.g. soup, sauces, gravies, pudding, yoghurt, salad dressing
- foods that will melt down to a liquid e.g. ice cream, frozen yoghurt, milkshakes/smoothies, ice blocks, ice cubes
- juicy fruits or vegetables e.g. melons (watermelon, rockmelon,honeydew, etc.), berries (strawberries, blueberries, raspberries, blackberries, etc.), tomatoes, cucumbers

To reduce thirst and alleviate dry mouth:
- eat a low salt diet (salty foods will increase your thirst)
- keep hard candies, mints and gum available. some people find sugar-freevarieties to be more thirst quenching
- brush your teeth
- chill mouthwash and gargle for a fresh feeling
- rinse your mouth with water (no swallowing).
- add lemon or cucumber to your water to help quench your thirst.
- freeze or partially freeze pieces of fruit for a refreshing treat: like lemon wedges, orange sections, peaches, berries, or grapes
- breathe through your nose and not your mouth
- avoid mid-day heat

The second and final visit (24 hours following the first) will involve exposure to a hot and dry environment (40 deg C and 20% relative humidity). You will walk at 5 km.h-1 and 1% gradient for 150 minutes. This will be conducted in five 30 minutes bouts, separated by 20 minutes rest. Before, during, and after this session several measures of hydration status (including changes in body weight, blood and urine samples) will be recorded during the rest periods. Nude body weight will be conducted alone in a lockable room. Blood samples (six by 6-ml collections) will be collected from a cannula inserted, by a trained phlebotomist, into the antecubital fossa of the elbow. The blood will be assessed for osmolality, a hydration marker, at each time point. Baseline urine samples will be assessed for specific gravity and colour. Heart rate, core and skin temperature will be recorded continuously. Heart rate will be measured with a chest strap and watch, core temperature via a rectal probe and skin temperature with four wireless sensors (approximately 1cm in diameter) placed on the surface of the skin. This session will be overseen by an exercise scientist and/or exercise physiologist accredited with Exercise and Sport Science Australia (ESSA).

The hydration MicrowearableTM sensor will also be worn continuously throughout this second visit. The MicrowearableTM is a disposable single-use device, developed by WearOptimo, it comprises an array of microelectrode-projections that upon application to skin, will penetrate the upper most layer of the skin. The sensor may be placed on the following locations: shoulder, sternum, and hand. Bioimpedance spectroscopy (BIS), which has been developed as a measure of body composition and fluid volume status, is used to continuously measure skin tissue composition between the microelectrode-projections.

The washout period prior to undertaking the alternative condition will be at least 7 days.
Intervention code [1] 324664 0
Diagnosis / Prognosis
Comparator / control treatment
Exercise-induced dehydration with fluid replacement

This single visit (24 hours following the first) will involve exposure to a hot and dry environment (40 deg C and 20% relative humidity). You will walk at 5 km.h-1 and 1% gradient for 150 minutes. This will be conducted in five 30 minutes bouts, separated by 20 minutes rest. Before, during, and after this session several measures of hydration status (including changes in body weight, blood and urine samples) will be recorded during the rest periods. Nude body weight will be conducted alone in a lockable room. Blood samples (six by 6-ml collections) will be collected from a cannula inserted, by a trained phlebotomist, into the antecubital fossa of the elbow. The blood will be assessed for osmolality, a hydration marker, at each time point. Baseline urine samples will be assessed for specific gravity and colour. Heart rate, core and skin temperature will be recorded continuously. Heart rate will be measured with a chest strap and watch, core temperature via a rectal probe and skin temperature with four wireless sensors (approximately 1cm in diameter) placed on the surface of the skin. Fluid lost through sweating will be replaced throughout the session with isotonic drinks (i.e. Gatorade) and water. The volume of fluid provided will be dictated by the weight change during the preceding 30-minute exercise bout. This session will be overseen by an exercise scientist and/or exercise physiologist accredited with Exercise and Sport Science Australia (ESSA).

The hydration MicrowearableTM sensor will be worn throughout this final visit. The MicrowearableTM is a disposable single-use device, developed by WearOptimo, it comprises an array of microelectrode-projections that upon application to skin, will penetrate the upper most layer of the skin. The sensor may be placed on the following locations: shoulder, sternum, and hand. Bioimpedance spectroscopy (BIS), which has been developed as a measure of body composition and fluid volume status, is used to continuously measure skin tissue composition between the microelectrode-projections.

The washout period prior to undertaking the alternative condition will be at least 7 days.

This single session does NOT include a visit 24 hours prior to the exercise session, as fluid minimisation/dehydration is not the goal. Rather fluid maintenance is the objective of the comparator treatment.
Control group
Active

Outcomes
Primary outcome [1] 333866 0
Diagnostic performance of Microwearable for detection of the dehydrated state.

Diagnostic performance will be determined by receiver operating characteristic (ROC) analysis of a binary classification distinguishing euhydrated and dehydrated states, in the validation group.
The area under the curve (AUC) and its 95% confidence interval will be calculated to determine the predictive performance of the Microwearable. A participant’s hydration status will be defined using a 2% body mass loss and 295 mOsm/kg serum osmolality (determined by blood test) cut off, as well documented in the literature, with values <2% and 295 mOsm/kg considered hydrated, and values >2% and 295 mOsm/kg considered dehydrated. True positive and negatives, as well as false positive and negatives will be identified.
Timepoint [1] 333866 0
Post 150 minutes of exercise of both exercise sessions
Secondary outcome [1] 418563 0
Diagnostic performance of Microwearable for detection of the dehydrated state.

Diagnostic performance will be determined by receiver operating characteristic (ROC) analysis of a binary classification distinguishing euhydrated and dehydrated states, in the validation group.
The area under the curve (AUC) and its 95% confidence interval will be calculated to determine the predictive performance of the Microwearable. A participant’s hydration status will be defined using a 2% body mass loss and 295 mOsm/kg serum osmolality (determined by blood test) cut off, as well documented in the literature, with values <2% and 295 mOsm/kg considered hydrated, and values >2% and 295 mOsm/kg considered dehydrated. True positive and negatives, as well as false positive and negatives will be identified.
Timepoint [1] 418563 0
Pre-exercise and following 30, 60, 90 and 120 minutes of exercise for both exercise sessions

Eligibility
Key inclusion criteria
To be eligible for study entry participants must satisfy all of the following criteria:
1. Male or female over 18 years of age, inclusive at the time of screening;
2. Generally healthy and considered to be of ‘Low Risk’ for suffering from an adverse event during physical activity per the Exercise and Sports Science Australia (ESSA) adult pre-exercise screening tool;
3. Partake on average in greater than or equal to 150-minutes weighted physical activity per week; with an emphasis on endurance exercise;
4. Able to provide voluntary, written informed consent with comprehension of all aspects of the protocol, prior to any study procedures.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Participants will be excluded from the study if one or more of the following criteria are applicable:
1. Have an implanted pacemaker or cardiogenic device;
2. Have a known skin allergy to gold;
3. Has any known blood clotting disorders (e.g., hemophilia), or taking any blood thinning medications or have any red blood cell disorders (e.g., thalassemia) (due to the requirement for blood collection during the study);
4. Women who are pregnant or breast feeding;
5. Identified as ‘Higher Risk Participants’ (i.e., answered ‘Yes’ to any of the Stage 1 questions via the ESSA adult pre-exercise screening tool);
6. Concurrently participating in any other clinical study.

Study design
Purpose of the study
Diagnosis
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation to which condition would be delivered first to each participant in this cross over trial was performed by an a priori randomisation schedule that involves a balanced block design. Staff involved in the enrolment of participants will be aware of the randomisation schedule, and therefore allocation is not concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation) with four equal blocks of 10
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Data acquired from the first two groups of at least 10 completed participants (first and second train-test data sets) will be to inform iterative development of the sensor geometry and hydration index algorithm. Within each of these groups, a hold-out set of at least 3 participants will be reserved (test data set) so that preliminary performance on out-of-sample data can inform development at each iteration. Machine learning model selection and optimization of algorithm parameters will be conducted using data of all other participants (the training data set) by applying a leave-one-participant-out cross-validation design within the training set.
The hydration index algorithms to be evaluated apply signal processing (time-frequency analysis, complex-valued independent component analysis of transformed impedance data) and computational Bayesian inference (Markov Chain Monte Carlo and Stochastic Variational Inference), with the latter applied to fit biophysical models of epidermal tissue and the sensor-tissue interface, extending the Cole-Cole model of dielectric relaxation (Cole and Cole, 1941), which is the model used in existing hydration measurement products (Kyle et al. 2004).
Following analysis of data from the second pilot group, the results of the exploratory investigation will be assessed. This is a decision point to determine whether the current iteration of sensor and hydration algorithm is sufficiently mature to justify proceeding directly to the final stage of the study, analytical validation to quantify diagnostic performance. Criteria for this decision are:
1. Preliminary performance on the out-of-sample test data set, which is necessarily incomplete statistical evidence due to the limited sample size;
2. The strength and interpretability of group-level associations between hydration state and the machine learning data features identified in the exploratory investigation; and
3. Any signal quality issues identified in the exploratory investigation.

On successful completion of iterative development, the optimal sensor characteristics and algorithm parameters determined will then be fixed, and diagnostic performance evaluated using the final group of 15 participants (validation data set), with sensitivity and specificity of detection of the dehydrated state determined by receiver operating characteristic (ROC) analysis of a binary classification distinguishing euhydrated and dehydrated states.
The area under the curve (AUC) and its 95% confidence interval will be calculated to determine the predictive performance of the device. The AUC and 95% confidence interval will be calculated using the ‘cvAUC’ R package (LeDell, Petersen & van der Laan, 2014). If missing data are present, the analysis will be run twice to determine the influence of missingness on the results: (1) using complete cases only; and (2) after imputing missing values using multiple imputation.
A participant’s hydration status will be defined using a 2% body mass loss cut off, as well documented in the literature, with values <2% considered hydrated, and values >2% considered dehydrated. True positive and negatives, as well as false positive and negatives will be identified.
A sample size of 15 participants was determined via simulation methods and was selected based on the precision of the 95% confidence interval of the area under the curve (AUC), from receiver operating characteristic (ROC) analysis. We considered scenarios where hydration status was incorrectly classified in 5, 10 and 20% of cases, at sample sizes of 5, 10 and 15 participants. At a sample of 15 participants each completing two exercise trials, the worst-case scenario (i.e., the hydration status of 20% of the data incorrectly classified) resulted in a 95% confidence interval on the AUC of .78 to 1—a range considered good (.8 to .9) to excellent (.9 to 1) performance.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
27/03/2023
Actual
21/03/2023
Date of last participant enrolment
Anticipated
1/07/2024
Actual
Date of last data collection
Anticipated
30/08/2024
Actual
Sample size
Target
45
Accrual to date
29
Final
Recruitment in Australia
Recruitment state(s)
QLD

Funding & Sponsors
Funding source category [1] 312464 0
Commercial sector/Industry
Name [1] 312464 0
WearOptimo
Country [1] 312464 0
Australia
Primary sponsor type
Commercial sector/Industry
Name
WearOptimo
Address
2 Heaslop St
Woolloongabba
Queensland, 4102
Country
Australia
Secondary sponsor category [1] 314043 0
None
Name [1] 314043 0
Address [1] 314043 0
Country [1] 314043 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 311809 0
Queensland University of Technology Human Research Ethics Committee
Ethics committee address [1] 311809 0
PO Box: OREI
Office of Research Ethics and Integrity
GPO Box 2434
QLD 4000
Ethics committee country [1] 311809 0
Australia
Date submitted for ethics approval [1] 311809 0
10/02/2023
Approval date [1] 311809 0
10/03/2023
Ethics approval number [1] 311809 0
4795

Summary
Brief summary
WearOptimo is developing the MicrowearableTM Hydration Sensor (the Microwearable) that utilizes localized impedance measurements to monitor, in real-time, changes in hydration. The Microwearable has been designed on the hypothesis that mild, systemic dehydration can be detected through changes in the impedance characteristics of the skin. By passing a small alternating current between microneedles that have been painlessly inserted into the uppermost layers of the skin, detection and notification of dehydration status can be provided to the Microwearable user.
This study will be the first in-human study of the WearOptimo Microwearable Hydration Sensor.
A key question for the feasibility of the Microwearable is whether dehydration at the systemic level will produce a corresponding pattern of changes in skin impedance that is consistent enough to support dehydration detection and diagnosis, against the background of natural confounding processes (sweat, motion, heart rate, blood pressure and local skin temperature changes).
To monitor contrasting levels of hydration, each participant will attend two trials with intervals of light exercise:
• Exercise in a hot and dry environment with continuous fluid replacement;
• Restriction of fluids for 24-hours followed by exercising in a hot and dry environment.
The primary endpoint will be the diagnostic performance of the Microwearable for detection of the dehydrated state. Diagnostic performance will be evaluated with sensitivity and specificity of detection of the dehydrated state determined by receiver operating characteristic (ROC) analysis of a binary classification distinguishing euhydrated and dehydrated states.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 122438 0
Prof Ian Stewart
Address 122438 0
Queensland University of Technology
60 Musk Ave
Kelvin Grove
QLD, 4059
Country 122438 0
Australia
Phone 122438 0
+61 7 3138 6118
Fax 122438 0
Email 122438 0
i.stewart@qut.edu.au
Contact person for public queries
Name 122439 0
Prof Ian Stewart
Address 122439 0
Queensland University of Technology
60 Musk Ave
Kelvin Grove
QLD, 4059
Country 122439 0
Australia
Phone 122439 0
+61 7 3138 6118
Fax 122439 0
Email 122439 0
i.stewart@qut.edu.au
Contact person for scientific queries
Name 122440 0
Prof Ian Stewart
Address 122440 0
Queensland University of Technology
60 Musk Ave
Kelvin Grove
QLD, 4059
Country 122440 0
Australia
Phone 122440 0
+61 7 3138 6118
Fax 122440 0
Email 122440 0
i.stewart@qut.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Commercial-in-confidence contract agreement with trial sponsor


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

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No documents have been uploaded by study researchers.

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No additional documents have been identified.