Autoimmune comorbid diseases associated with lichen planus: a nationwide case-control study.

BackgroundLichen planus (LP) is a chronic inflammatory disorder with unknown aetiology. The association between LP and various autoimmune diseases has been reported, but nationwide study of the relationship of LP with associated diseases is quite limited. ObjectiveOur study aims to clarify the association between LP and a variety of autoimmune diseases in Taiwanese. MethodsData were obtained from the National Health Insurance Research Database (NHIRD) of Taiwan from 1997 to 2011. In total, 12427 patients with LP and 49708 age- and gender-matched controls were enrolled. ResultsAmong patients with LP, there were significant associations with systemic lupus erythematosus (SLE) (multivariate odds ratio [mOR]: 2.87; 95% CI: 1.97-4.17), Sjogren's syndrome (mOR: 3.75; 95% CI: 2.66-5.28), dermatomyositis (mOR: 6.34; 95% CI: 1.82-22.16), vitiligo (mOR: 2.09; 95% CI: 1.31-3.32) and alopecia areata (mOR: 2.82; 95% CI: 2.20-3.62). On gender-stratified analyses, SLE and alopecia areata were significantly associated with LP in both genders. The association with Sjogren's syndrome was significant only in female patients. The associations with dermatomyositis and vitiligo became insignificant in both genders. ConclusionLichen planus is associated with various autoimmune diseases. Further study is required to elucidate the possible underlying mechanisms and roles of autoimmunity in the aetiology of LP.