title: Differences in Comorbidity Profiles between Early-Onset and Late-Onset Alopecia Areata Patients: A Retrospective Study of 871 Korean Patients.
abstract: BACKGROUND
  Alopecia areata (AA) is a common dermatologic condition with a broad spectrum of clinical features and age of onset, classically characterized by nonscarring patches of hair loss. In the past, early-onset (before adolescence) AA has been associated with various autoimmune diseases, especially atopic diseases and lupus erythematosus and demonstrates a worse prognosis compared with late onset AA.
  
  
  OBJECTIVE
  To evaluate the differences in the comorbidity profile of AA with regard to age at onset.
  
  
  METHODS
  We completed a retrospective study of 871 Korean AA patients seen at our department within the last 10 years. After these patients were subdivided according to onset before or after age 13 years, the two groups were compared on the basis of their comorbid disorders, family history of AA, and hematologic test results.
  
  
  RESULTS
  Our results demonstrate that significantly more patients in the early-onset group had a personal history of atopic dermatitis or family history of AA. These findings are consistent with previous reports associating early-onset AA with autoimmune diseases and a family history of AA in different ethnic populations. Most of the serologic test values showed no significant differences between the groups and the results were considerably affected by age.
  
  
  CONCLUSIONS
  This study is significant because it is a large group study in Korean AA patients, and Korean AA patients with an onset age before adolescence show similar clinical manifestations to other ethnic populations.
authors.affiliation: Department of Dermatology, Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Noo Ri
authors.initials: NR
authors.lastname: Lee
authors.affiliation: Department of Dermatology, Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Bo-Kyung
authors.initials: BK
authors.lastname: Kim
authors.affiliation: Department of Dermatology, Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Na Young
authors.initials: NY
authors.lastname: Yoon
authors.affiliation: Department of Dermatology, Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Sung-Yul
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Dermatology, Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Seok-Yong
authors.initials: SY
authors.lastname: Ahn
authors.affiliation: Department of Dermatology, Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Won-Soo
authors.initials: WS
authors.lastname: Lee
keywords: Alopecia areata; Autoimmune diseases; Comorbidity; Onset age