title: Pemphigus and associated comorbidities: a cross-sectional study.
abstract: BACKGROUND
  Pemphigus is a rare autoimmune blistering disease, reported to be associated with other coexisting and autoimmune diseases, including thyroid diseases, rheumatoid arthritis, alopecia areata, vitiligo, systemic lupus erythematosus, scleroderma and rare entities such as myasthenia gravis.
  
  
  OBJECTIVE
  To identify and describe patients with pemphigus with a diagnosed comorbidity, and to quantify the risk of additional comorbidities.
  
  
  METHODS
  This was a cross-sectional study of patients with pemphigus treated at a tertiary referral centre. Prevalence rates of 15 comorbid diseases were calculated. Age-standardized prevalence ratio (SPR) and 95% CI were calculated in comparison with prevalence rates in the general Canadian population using data from the Canadian Community Health Survey. Data were analysed using SAS software.
  
  
  RESULTS
  In total, 295 patients were identified. An increased risk of hypothyroidism (n = 38, SPR = 1.53, 95% CI 1.08-2.10) and inflammatory bowel disease (IBD) (SPR = 1.48, 95% CI 0.40-3.80), and a two-fold increased risk of diabetes (SPR = 2.20, 95% CI 1.64-2.87) were observed.
  
  
  CONCLUSIONS
  Patients with pemphigus have a higher incidence of hypothyroidism, IBD and diabetes compared with the general population. As part of pemphigus investigations and surveillance, investigating for these conditions may be considered.
authors: Division of Dermatology, ON, Canada.
authors: K
authors: K
authors: Heelan
authors: Department of Public Health Sciences, Queen's University , Kingston, ON, Canada.
authors: A L
authors: AL
authors: Mahar
authors: Division of Dermatology, ON, Canada.
authors: S
authors: S
authors: Walsh
authors: Division of Dermatology, ON, Canada.|Division of Clinical Pharmacology and Toxicology at Sunnybrook, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto, ON, Canada.
authors: N H
authors: NH
authors: Shear
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D002908:Chronic Disease / Q000453:epidemiology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010392:Pemphigus / Q000453:epidemiology*; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult