Validity and reliability evidence of a point of care assessment of salivary cortisol and α -amylase: a pre-registered study

• Published in: PeerJ (San Francisco, CA) CA), 2020-01, Vol.8, p.e8366-e8366, Article e8366
• Main Authors: Ducker, Kagan J, Lines, Robin L J, Chapman, Michael T, Peeling, Peter, McKay, Alannah K A, Gucciardi, Daniel F
• Format: Article
• Language: English
• Subjects: Age; Age determination; Anatomy and Physiology; Circadian rhythm; Cortisol; Diabetes and Endocrinology; Drugs and Devices; Enzyme-linked immunosorbent assay; Exercise; Heart rate; Hormones; Kinesiology; Laboratories; Medical research; Metabolites; Methods; Physical fitness; Psychophysiology; Saliva; Stress; Studies; α-Amylase
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.8366

The iPro Cube is a small portable point-of-care device designed to analyse salivary markers of stress in a user-friendly manner (e.g., fast, convenient). Our aim was to test the reliability and validity of the iPro Cube to measure salivary cortisol and -amylase as compared to the common laboratory standard method (ELISA immunoassay) prior to and after moderate intensity exercise. The study was a repeated measures, pre-registered design, and statistical framework that incorporated prior knowledge directly into the estimation process. Twenty-nine individuals (age = 27.4 ± 6.6 y; body-mass = 70.8 ± 11.3 kg; height = 1.74 ± 0.92 m; 18 males) completed a single PWC , with repeated measures of salivary cortisol and -amylase pre, immediately post, and 30 min post-exercise. Correlation between the iPro Cube and laboratory-based assessments of salivary cortisol was moderate-to-large (0.53 > < 0.81) across all three testing points. In contrast, correlation between the iPro Cube and laboratory-based assessments of -amylase was small-to-moderate (0.25 > < 0.46). We found a large correlation between duplicate samples of iPro Cube cortisol assessment (0.75 > < 0.82), and a moderate-to-large correlation for -amylase (0.51> < 0.77). The iPro Cube is capable of taking measures of salivary cortisol that are moderately correlated to values obtained via ELISA immunoassay, however the unit underestimates salivary cortisol and overestimates salivary -amylase at rest and post-moderate intensity exercise. It is recommended that researchers continue using standard laboratory techniques to assess these salivary stress markers.