Comfortable, Valid and Reliable? Measuring Stress in Children with ASD Using Select Consumer-Grade Heart Rate Trackers

Background: New wearable monitoring devices have the potential to revolutionize psychophysiology research among people with ASD by bringing it to the settings that matter – out of the laboratory and into schools and homes. However, due to sensory sensitivities, people with ASD may not be comfortable wearing such devices. In addition, formal testing of the reliability and validity of such devices among people with ASD is limited.

Objectives: This study tested whether commercially-available heart rate trackers (1) can be comfortably worn by children with ASD, and (2) validly and reliably measure stress in children with ASD.

Methods: 55 children, 32 with ASD and 23 without ASD, 8-12 years old were fitted with four heart rate trackers, including one chest-strap (Polar H7), two wrist-bands (Mio Fuse and Pulse On), and one set of headphones (Jabra). They participated in a two-hour battery that included a rest task (watching a relaxing video) and low-level stress tasks taken from the Laboratory Temperament Assessment Battery, including the transparent box task. Heart rate (beats per minute; BPM) and heart rate variability (R-R interval) data were recorded simultaneously from each of the devices with custom software. Researchers administered the Comfort Rating Scales to children at the end of the session; children rated the devices on eight dimensions: 1) Emotion (I feel tense or on edge because I am wearing the device); 2) Attachment (I can feel the device on my body); 3) Harm (the device is causing me some harm); 4) Perceived change (I feel strange wearing the device); 5) Movement (the device affects the way I move); 6) Anxiety (I do not feel secure wearing the device); 7) Sensory sensitivity (the device feels annoying on my skin); 8) Attention on sensation (I cannot stop thinking about the feeling of the device on my skin). Validity of stress measurement was analyzed using BPM and R-R interval data in 2 groups (ASD, non-ASD) 2 tasks (rest, stress) repeated measures ANOVAs.

Results: Comfortability. As shown in Table 1, 85% of children with ASD kept the Mio Fuse wrist-band and Polar H7 chest-strap on during the entire session (fewer children kept the other devices on). Although the Polar H7 chest-strap was less comfortable for children with ASD than for children without ASD with regards to the Emotion and Movement dimensions, absolute scores show that, on average, all children found the devices comfortable (see Figure 1). Validity. In the stress relative to rest condition, heart rate went up for the Polar H7 chest-strap, F(1,41)=56.27, p<.001, ηp²=.58, and Mio Fuse wrist-band, F(1,40)=13.70, p=.001, ηp²=.26, respectively, and R-R interval (ms) went down for the Polar H7 chest-strap, F(1,41)=56.27, p<.001, ηp²=.58, and Mio Fuse wrist-band, F(1,40)=21.17, p<.001, ηp²=.35, respectively. Reliability. Presentation of results will include technical reliability data (spike rate and sampling fidelity).

Conclusions: Findings show that select heart rate devices may be used for measuring stress in children with ASD. Results from this study may inform methodologies used in future studies to measure physiological stress in children with autism in community settings.