title: A systematic review of the incidence and prevalence of autoimmune disease in multiple sclerosis.
abstract: BACKGROUND
  As new therapies emerge which increase the risk of autoimmune disease it is increasingly important to understand the incidence of autoimmune disease in multiple sclerosis (MS).
  
  
  OBJECTIVE
  The purpose of this review is to estimate the incidence and prevalence of comorbid autoimmune disease in MS.
  
  
  METHODS
  The PUBMED, EMBASE, SCOPUS and Web of Knowledge databases, conference proceedings, and reference lists of retrieved articles were searched, and abstracts were independently screened by two reviewers. The data were abstracted by one reviewer using a standardized data collection form, and the findings were verified by a second reviewer. We assessed quality of the included studies using a standardized approach and conducted meta-analyses of population-based studies.
  
  
  RESULTS
  Sixty-one articles met the inclusion criteria. We observed substantial heterogeneity with respect to the populations studied, methods of ascertaining comorbidity, and reporting of findings. Based solely on population-based studies, the most prevalent autoimmune comorbidities were psoriasis (7.74%) and thyroid disease (6.44%). Our findings also suggest an increased risk of inflammatory bowel disease, likely uveitis and possibly pemphigoid.
  
  
  CONCLUSIONS
  Fewer than half of the studies identified were of high quality. Population-based studies that report age, sex and ethnicity-specific estimates of incidence and prevalence are needed in jurisdictions worldwide.
authors.affiliation: Departments of Internal Medicine and Community Health Sciences, University of Manitoba, Canada rmarrie@hsc.mb.ca.
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
authors.affiliation: Departments of Internal Medicine and Community Health Sciences, University of Manitoba, Canada.
authors.forename: Nadia
authors.initials: N
authors.lastname: Reider
authors.affiliation: Mellen Center for MS Treatment and Research, Cleveland Clinic, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Cohen
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern, USA.
authors.forename: Olaf
authors.initials: O
authors.lastname: Stuve
authors.affiliation: Department of Neurology, Copenhagen University Hospital Rigshospitalet, Denmark.
authors.forename: Per S
authors.initials: PS
authors.lastname: Sorensen
authors.affiliation: Department of Biostatistics, University of Alabama at Birmingham, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Cutter
authors.affiliation: Scientific and Clinical Review Associates, LLC, USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Reingold
authors.affiliation: Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Trojano
mesh_terms: D001327:Autoimmune Diseases / Q000453:epidemiology*; D015897:Comorbidity; D006801:Humans; D015994:Incidence; D009103:Multiple Sclerosis / Q000453:epidemiology*; D015995:Prevalence
keywords: Multiple sclerosis; autoimmune disease; comorbidity; incidence; prevalence