Use of salivary diurnal cortisol as an outcome measure in randomised controlled trials: a systematic review
Annals of Behavioral Medicine
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Ryan, R., Booth, S., Spathis, A., Mollart, S., & Clow, A. (2016). Use of salivary diurnal cortisol as an outcome measure in randomised controlled trials: a systematic review. Annals of Behavioral Medicine, 50 210-236. https://doi.org/10.1007/s12160-015-9753-9
Background: Dysregulation of the hypothalamic - pituitary - adrenal (HPA) axis is associated with diverse adverse health outcomes, making it an important therapeutic target. Measurement of the diurnal rhythm of cortisol secretion provides a window into this system. At present, no guidelines exist for the optimal use of this biomarker within randomised controlled trials (RCTs). Purpose: To describe the ways in which salivary diurnal cortisol has been measured within RCTs of health or behavioural interventions in adults. Methods: Six electronic databases (up to May 21st 2015) were systematically searched for RCTs which used salivary diurnal cortisol as an outcome measure to evaluate health or behavioural interventions in adults. A narrative synthesis was undertaken of the findings in relation to salivary cortisol methodology and outcomes. Results: From 78 studies that fulfilled the inclusion criteria, 30 included healthy participants (38.5%), 27 included patients with physical disease (34.6%) and 21 included patients with psychiatric disease (26.9%). Psychological therapies were most commonly evaluated (n=33, 42.3%). There was substantial heterogeneity across studies in relation to saliva collection protocols and reported cortisol parameters. Only 39 studies (50%) calculated a rhythm parameter such as the diurnal slope or the cortisol awakening response (CAR). Patterns of change in cortisol parameters were inconsistent both within and across studies and there was low agreement with clinical findings. Conclusions: Salivary diurnal cortisol is measured inconsistently across RCTs, which is limiting the interpretation of findings within and across studies. This indicates a need for more validation work, along with consensus guidelines.
salivary cortisol, diurnal rhythm, randomized controlled trial, systematic review, intervention
Dr. Ryan is funded by a National Institute for Health Research (NIHR) Doctoral Research Fellowship Programme Award in the UK. The views expressed are those of the authors and not necessarily those of the National Health Service (NHS), the NIHR or the Department of Health.
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External DOI: https://doi.org/10.1007/s12160-015-9753-9
This record's URL: https://www.repository.cam.ac.uk/handle/1810/251436