title: Increased risk of systemic lupus erythematosus in 29,000 patients with biopsy-verified celiac disease.
abstract: OBJECTIVE
  To investigate a possible association between celiac disease (CD) and systemic lupus erythematosus (SLE). Case series have indicated a possible association, but population-based studies are lacking.
  
  
  METHODS
  We compared the risk of SLE in 29,048 individuals with biopsy-verified CD (villous atrophy, Marsh 3) from Sweden's 28 pathology departments with that in 144,352 matched individuals from the general population identified through the Swedish Total Population Register. SLE was defined as having at least 2 records of SLE in the Swedish Patient Register. We used Cox regression to estimate hazard ratios (HR) for SLE.
  
  
  RESULTS
  During followup, 54 individuals with CD had an incident SLE. This corresponded to an HR of 3.49 (95% CI 2.48-4.90), with an absolute risk of 17/100,000 person-years and an excess risk of 12/100,000. Beyond 5 years of followup, the HR for SLE was 2.54 (95% CI 1.57-4.10). While SLE was predominantly female, we found similar risk estimates in men and women. When we restricted our outcome to individuals who also had a dispensation for a medication used in SLE, the HR was 2.43 (95% CI 1.22-4.87). The HR for having 2 records of SLE diagnoses, out of which at least 1 had occurred in a department of rheumatology, nephrology/dialysis, internal medicine, or pediatrics, was 2.87 (95% CI 1.97-4.17).
  
  
  CONCLUSIONS
  Individuals with CD were at a 3-fold increased risk of SLE compared to the general population. Although this excess risk remained more than 5 years after CD diagnosis, absolute risks were low.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden. jonasludvigsson@yahoo.com
authors.forename: Jonas F
authors.initials: JF
authors.lastname: Ludvigsson
authors.forename: Alberto
authors.initials: A
authors.lastname: Rubio-Tapia
authors.forename: Vaidehi
authors.initials: V
authors.lastname: Chowdhary
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Murray
authors.forename: Julia F
authors.initials: JF
authors.lastname: Simard
mesh_terms: D000328:Adult; D002446:Celiac Disease / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012042:Registries; D012306:Risk; D013548:Sweden / Q000453:epidemiology