One size does not fit all: a scoping review on study population diversity in studies assessing the validity of consumer wearables for measuring vital signs

Background: Consumer wearables provide promising opportunities for early detection and prevention of disease through continuous remote monitoring of vital signs. However, before implementing consumer wearables into research and healthcare settings their validity needs to be assessed. As user characteristics like sex, BMI and skin tone could influence the validity of wearable sensors, it is important that different categories of these characteristics are represented in the studies assessing wearable validity. So far, no study has investigated this representation, which makes it difficult to identify gaps in representation and provide recommendations for future studies.<br/><br/>Objective: This scoping review aims to provide an overview of the representation and reporting of study population characteristics in studies that assess the validity of consumer wearables for measuring vital signs. These vital signs include heart rate, heart rate variability, blood pressure, blood oxygen saturation, respiratory rate and body temperature. <br/><br/>Methods: A search was conducted in Scopus, PubMed and IEEE Xplore databases in June 2024. Publications were eligible if they assessed the validity of one or more consumer wearables for one or more vital signs in humans compared to a reference method. Publications were excluded if: 1) the wearable assessed was a chest strap or not suitable for wear during daily activities; 2) the study included only one participant. <br/><br/>Results: After screening, a total of 161 studies were included. By extracting and synthesizing the study population characteristics for these studies, we will present gaps in reporting and representation of user characteristics including age, BMI and skin tone. Based on these findings, recommendations for reporting and representation for future studies will be provided. <br/><br/>Conclusion: This scoping review will contribute to a more inclusive transition to home-based healthcare by identifying gaps in reporting and representation of study population characteristics in consumer wearable validation studies. <br/>