Autoimmune disorders in oral lichen planus: A systematic review and meta-analysis

Objectives The association of OLP with other autoimmune processes points to the possibility that OLP-affected patients are actually developing an autoimmune status that predisposes them to autoaggression against different targets. This systematic review and meta-analysis aim to evaluate the current evidence on the prevalence of autoimmune disorders in patients with OLP and their magnitude of association. Methods We searched PubMed, Embase, Web of Science, Scopus databases for the studies published before May 2021, with no limitation in regards to their publication date or language. We evaluated the quality of studies, carried out meta-analyses and performed heterogeneity, subgroups, meta-regression, and small-study effects analyses. Results Inclusion criteria were met by 153 studies (23,327 patients). Our results indicate the existence of high prevalence and a frequent association between OLP and some autoimmune disorders, especially in regards to thyroid disease (PP = 7.96%, 95% CI = 6.32-9.75; OR = 1.99, 95% CI = 1.60-2.49, p < 0.001) and diabetes mellitus (PP = 9.41%,95% CI = 8.16-10.74; OR = 1.64, 95% CI = 1.34-2.00, p < 0.001). Conclusions Our study demonstrates the existence of a comorbidity between autoimmune thyroid diseases as well as between diabetes mellitus and OLP respectively. Quality of evidence should be upgraded on other autoimmune diseases (fibromyalgia, gastrointestinal disorders, rheumatic diseases, Sjogren's syndrome, lupus erythematosus, and dermatological diseases) for which the current data do not allow us to know whether they are really associated with OLP.