The effect of acute stress on salivary markers of inflammation: a systematic review protocol.

backgroundThere is an increasing interest in the ability to non-invasively assess biological markers of stress. Measures of inflammation following exposure to acute stress have been assessed in saliva, but a systematic review and meta-analysis of the reliability of changes in response to stress has not been conducted. The proposed review aims to update and extend a prior review of this literature by performing a systematic review and meta-analysis, conducting moderator analyses, summarizing and reviewing best practices, and providing recommendations for future research. METHODS AND ANALYSIS: The adopted search strategy will involve the electronic databases PubMed, PsycINFO, and Embase. We will include the articles identified by a 2015 narrative review on a similar topic, as well as use reference treeing to identify additional potentially relevant articles. Identified articles will be independently screened by title and abstract. The full text of potentially relevant articles will then be retrieved and read for full inclusion criteria. Data will be extracted, and random-effects meta-analyses will be conducted in R for articles determined to meet all inclusion criteria. The primary outcome will be the magnitude of changes in inflammatory biomarkers following acute stress exposure, as indicated by Cohen's d. Participant psychosocial or demographic (e.g., age, gender/sex, race/ethnicity, salivary flow rate, oral health status, health status) and methodological (e.g., stressor type, sample timing, assay technique, sample collection method, study quality) moderators of this response also will be examined using meta-regression. DISCUSSION: This systematic review will synthesize the evidence regarding salivary markers of inflammation in response to acute stress. We anticipate variation across studies but hypothesize that salivary markers of inflammation will increase in response to acute stress. The evidence obtained for this study will help guide future research by providing guidelines for the design and measurement of studies assessing salivary inflammation in response to acute stress. Findings will be disseminated with a peer-reviewed manuscript and an international conference presentation.