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

Abstract

Purpose. 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 α-amylase as compared to the common laboratory standard method (ELISA immunoassay) prior to and after moderate intensity exercise. Methods. 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 75%HRmax , with repeated measures of salivary cortisol and ÉŚ-amylase pre, immediately post, and 30 min post-exercise. Results. Correlation between the iPro Cube and laboratory-based assessments of salivary cortisol was moderate-to-large (0.53 > r < 0.81) across all three testing points. In contrast, correlation between the iPro Cube and laboratory-based assessments of ÉŚ-amylase was small-to-moderate (0.25 > r < 0.46). We found a large correlation between duplicate samples of iPro Cube cortisol assessment (0.75 > r < 0.82), and a moderate-to-large correlation for ÉŚ-amylase (0.51> r < 0.77). Conclusions. 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 ÉŚ-amylase at rest and post-moderate intensity exercise. It is recommended that researchers continue using standard laboratory techniques to assess these salivary stress markers.How to cite this article Ducker KJ, Lines RLJ, Chapman MT, Peeling P, McKay AKA, Gucciardi DF. 2020. Validity and reliability evidence of a point of care assessment of salivary cortisol and α-amylase: a pre-registered study. PeerJ 8:e8366 http://doi.

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