The Validity of the Salivary Cortisol Analysis Method Using the Cube Reader in Japanese University Students
Hisashi Mitsuishi, Hisayoshi Okamura, Yusuke Moriguchi, Yoshiko Aoki
Abstract
Abstract The assessment of salivary cortisol is considered a noninvasive method for measuring stress. The validity of the SOMA Cube Reader method to measure salivary cortisol was evaluated by comparing the results with those of the long‐used enzyme‐linked immunosorbent assay method (ELISA) in 18 healthy Japanese university students (including non‐athletes). We measured diurnal salivary cortisol levels (immediately post‐awakening, 30 min post‐awakening, and at 11:00, 14:00, and 17:00). Measurements obtained by both methods were compared using analyses of variance. No significant main effects or interactions were demonstrated. Significant positive correlations were noted between the ELISA and Cube Reader measurements across all five testing points, the cortisol awakening response, the daily output, and the diurnal cortisol slope ( r s = .50–.75). Moreover, the limits of agreement between the Cube Reader and the ELISA results were assessed via a Bland–Altman graph, showing good agreement with no bias. The results obtained with the Cube Reader method correlated with values obtained using the ELISA method, confirming the potential to use the Cube Reader for measuring diurnal salivary cortisol levels in healthy Japanese university students, including non‐athletes.