Introducing polyautoimmunity: secondary autoimmune diseases no longer exist

Abstract

Similar pathophysiological mechanisms within autoimmune diseases have stimulated searches for common genetic roots. Polyautoimmunity is defined as the presence of more than one autoimmune disease in a single patient. When three or more autoimmune diseases coexist, this condition is called multiple autoimmune syndrome (MAS). We analyzed the presence of polyautoimmunity in 1,083 patients belonging to four autoimmune disease cohorts. Polyautoimmunity was observed in 373 patients (34.4%). Autoimmune thyroid disease (AITD) and Sjögren's syndrome (SS) were the most frequent diseases encountered. Factors significantly associated with polyautoimmunity were female gender and familial autoimmunity. Through a systematic literature review, an updated search was done for all MAS cases (January 2006-September 2011). There were 142 articles retrieved corresponding to 226 cases. Next, we performed a clustering analysis in which AITD followed by systemic lupus erythematosus and SS were the most hierarchical diseases encountered. Our results indicate that coexistence of autoimmune diseases is not uncommon and follows a grouping pattern. Polyautoimmunity is the term proposed for this association of disorders, which encompasses the concept of a common origin for these diseases.

Figure 1

Flow chart of the systematic literature review. ADs: autoimmune diseases; MAS: multiple autoimmune syndrome.

Figure 2

Cluster analysis dendogram. Each node represets a stage from the clustering process. There were four clusters. The most hierarchical was composed of four ADs. AITD: autoimmune thyroid disease (including thyroiditis, Hashimoto disease, Graves disease); SLE: systemic lupus erythematosus; SS: Sjögren's syndrome; APS: antiphospholipid syndrome; T1D: type 1 diabetes mellitus; SSc: scleroderma (including localized, systemic, diffuse, limited); BID: billiary inflammatory disease (including primary biliary cirrhosis, primary sclerosing cholangitis); CD: celiac disease; VIT: vitiligo; AIH: autoimmune hepatitis; RA: rheumatoid arthritis; MG: myasthenia gravis; PMDM: polymyositis/dermatomyositis; PA: pernicious anemia; DAD: demyelinating autoimmune diseases (including multiple sclerosis, transverse myelitis, optic neuromyelitis); AAI: autoimmune adrenal insufficiency (Addison disease); HA: autoimmune anemia; ITP: idiopathic thrombocytopenic purpura; AG: autoimmune gastritis; VAS: vasculitis (including Churg-Strauss syndrome, giant cell arteritis, microscopic polyangiitis, cryoglobulinemia, polyarteritis nodosa, Wegener granulomatosis); PF: pemphigus (including vulgaris, bulloso, foliaceous); IBD: inflammatory bowel disease (including ulcerative colitis, Crohn's disease); AA: alopecia areata; PsA: psoriasis (including psoriatic arthritis); SAR: sarcoidosis; JCA: juvenile chronic arthritis; AS: ankylosing spondylitis; RePo: relapsing polychondritis.