CARWatch – A smartphone application for improving the accuracy of cortisol awakening response sampling

Richer R, Abel L, Küderle A, Eskofier B, Rohleder N (2023)


Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2023

Journal

Book Volume: 151

Pages Range: 106073

Article Number: 106073

URI: https://www.sciencedirect.com/science/article/abs/pii/S0306453023000513

DOI: 10.1016/j.psyneuen.2023.106073

Abstract

Background

Many studies investigating the cortisol awakening response (CAR) suffer from low adherence to the study protocol as well as from the lack of precise and objective methods for assessing the awakening and saliva sampling times which leads to measurement bias on CAR quantification.


Methods

To address this issue, we have developed “CARWatch”, a smartphone application that aims to enable low-cost and objective assessment of saliva sampling times as well as to concurrently increase protocol adherence. As proof-of-concept study, we assessed the CAR of N=117 healthy participants (24.2 ± 8.7 years, 79.5% female) on two consecutive days. During the study, we recorded awakening times (AW) using self-reports, the CARWatch application, and a wrist-worn sensor, and saliva sampling times (ST) using self-reports and the CARWatch application. Using combinations of different AW and ST modalities, we derived different reporting strategies and compared the reported time information to a Naive sampling strategy assuming an ideal sampling schedule. Additionally, we compared the AUCI, computed using information from different reporting strategies, against each other to demonstrate the effect of inaccurate sampling on the CAR.


Results

The use of CARWatch led to a more consistent sampling behavior and reduced sampling delay compared to self-reported saliva sampling times. Additionally, we observed that inaccurate saliva sampling times, as resulting from self-reports, were associated with an underestimation of CAR measures. Our findings also revealed potential error sources for inaccuracies in self-reported sampling times and showed that CARWatch can help in better identifying, and possibly excluding, sampling outliers that would remain undiscovered by self-reported sampling.


Conclusion

The results from our proof-of-concept study demonstrated that CARWatch can be used to objectively record saliva sampling times. Further, it suggests its potential of increasing protocol adherence and sampling accuracy in CAR studies and might help to reduce inconsistencies in CAR literature resulting from inaccurate saliva sampling. For that reason, we published CARWatch and all necessary tools under an open-source license, making it freely accessible to every researcher.

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How to cite

APA:

Richer, R., Abel, L., Küderle, A., Eskofier, B., & Rohleder, N. (2023). CARWatch – A smartphone application for improving the accuracy of cortisol awakening response sampling. Psychoneuroendocrinology, 151, 106073. https://doi.org/10.1016/j.psyneuen.2023.106073

MLA:

Richer, Robert, et al. "CARWatch – A smartphone application for improving the accuracy of cortisol awakening response sampling." Psychoneuroendocrinology 151 (2023): 106073.

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