title: Systemic sclerosis at the crossroad of polyautoimmunity.
abstract: OBJECTIVE
  Several epidemiological studies have revealed the co-occurrence of other autoimmune diseases (AIDs) within patients with systemic sclerosis (SSc). However, some of these studies were based on small cohorts and wide ranges of prevalence have been reported. Therefore to overcome these limitations of individual studies, we sought to perform a meta-analysis to determine the accurate prevalence of polyautoimmunity in SSc.
  
  
  METHODS
  We performed a systematic review and a meta-analysis of literature in MEDLINE and Embase databases from January 1960 to March 2013. All cohort studies reporting on prevalence of other AIDs known to be associated with SSc were analyzed. Prevalence of polyautoimmunity and of each AID were then calculated.
  
  
  RESULTS
  Ten studies reporting polyautoimmunity were identified corresponding to a total of 6102 SSc patients. Overall 1432 patients with at least one AID were identified corresponding to a weighted prevalence of polyautoimmunity equal to 25.7% CI 95% [20.1%-31.6%]. Overall 208/5139 SSc-patients had at least two additional AIDs resulting in a weighted prevalence of 3.9% [3.3%-4.4%]. The most prevalent associated AIDs were autoimmune thyroid disease (10.4%) followed by Sjögren's syndrome (7.7%) and dermatopolymyositis/polymyositis (5.6%).
  
  
  CONCLUSIONS
  Our results confirm that SSc polyautoimmunity is a frequent condition in SSc affecting a quarter of SSc-patients. The impact on the phenotype and also on the management and therapy will need to be addressed now in further works.
authors.affiliation: Rheumatology A Dpt, Paris Descartes University, Sorbonne Paris Cite, Cochin Hospital, APHP, 27 rue du Faubourg Saint-Jacques, 75014 Paris, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Elhai
authors.forename: Jerôme
authors.initials: J
authors.lastname: Avouac
authors.forename: André
authors.initials: A
authors.lastname: Kahan
authors.forename: Yannick
authors.initials: Y
authors.lastname: Allanore
mesh_terms: D001327:Autoimmune Diseases / Q000150:complications* / Q000453:epidemiology / Q000235:genetics; D015331:Cohort Studies; D006801:Humans; D010641:Phenotype; D015995:Prevalence; D012595:Scleroderma, Systemic / Q000150:complications* / Q000235:genetics / Q000276:immunology*; D012859:Sjogren's Syndrome / Q000150:complications* / Q000235:genetics / Q000276:immunology*
keywords: Autoimmunity; Connective tissue diseases; Overlap; Systemic autoimmune disease; Systemic sclerosis