Salivary biomarkers to evaluate psychological disorders in oral lichen planus: a systematic review with meta‐analysis

Objective To analyze the use of salivary biomarkers to identify psychological disorders (anxiety, depression, and stress) in individuals with oral lichen planus (OLP). Materials and Methods The search was made in Medline/Pubmed, Scopus, Web of Science, Virtual Health Library, ProQuest, and by cross-reference. Original case-control, cross-sectional, and cohort studies, in human subjects (age >= 18 years) with clinical and histopathological diagnosis, with or without the use of psychometric scales, published until June 2021, were included. Random-effects meta-analyses, subgroup analyses, and sensitivity were performed. Publication bias was measured using the Egger test and visual inspection of the funnel plot. Results A total of 67 articles were found, of which 12 were included in the meta-analysis. Among the different biomarkers identified, it was only possible to perform a meta-analysis for cortisol. The mean difference between salivary cortisol levels in patients with OLP compared to controls was 3.43 ng/ml (95% CI: 1.20-5.65) with I-2 = 98.9%. Studies considered outliers were removed and based on sensitivity analyses, results did not change, therefore, being stable. Conclusion The studies analyzed demonstrated that cortisol was the most quantified biomarker to identify psychological disorders; however, DHEA, IgA, adiponectin, and alpha-amylase were also evaluated.