title: Low prevalence of psoriasis among children and adolescents in a large multiethnic cohort in southern California.
abstract: BACKGROUND
  Little information is available on the prevalence of psoriasis in children and adolescents.
  
  
  OBJECTIVE
  We sought to estimate the prevalence of pediatric psoriasis in southern California and to investigate the validity of psoriasis diagnosis by a dermatologist compared with a nondermatologist.
  
  
  METHODS
  In a southern California population of 710,949 children who were enrolled in an integrated prepaid health plan in 2007 through 2008, cases of psoriasis were identified from electronic medical records and validated by medical chart review. Positive predictive values for valid diagnosis were reported for dermatologists and nondermatologists.
  
  
  RESULTS
  The prevalence of pediatric psoriasis confirmed by medical chart review was 19/10,000 patients. The prevalence of psoriasis diagnosis (confirmed and unconfirmed) was 30/10,000 patients. The age at onset of psoriasis was slightly earlier in boys than in girls. The positive predictive value for a valid diagnosis of psoriasis was 63.7% when the diagnosis was made by any health care provider, 90.0% by a dermatologist, and 26.6% by a nondermatologist. The prevalence of psoriasis was higher in girls than in boys. Psoriasis affected 29 (95% confidence interval [CI] 27-32) non-Hispanic whites, 20 (95% CI 16-24) Asian/Pacific Islanders, 16 (95% CI 15-18) Hispanic whites, and 6 (95% CI 4-9) blacks per 10,000 patients.
  
  
  CONCLUSIONS
  Information on the age at onset was estimated based on the first documented diagnosis of psoriasis.
  
  
  CONCLUSIONS
  The overall prevalence of pediatric psoriasis was lower compared with other published studies. This could be in part a result of underdiagnosis because of greater sunlight exposure in southern California and a lower proportion of non-Hispanic whites in the population.
authors.affiliation: Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California, USA. jashinwu@hotmail.com
authors.forename: Jashin J
authors.initials: JJ
authors.lastname: Wu
authors.forename: Mary Helen
authors.initials: MH
authors.lastname: Black
authors.forename: Ning
authors.initials: N
authors.lastname: Smith
authors.forename: Amy H
authors.initials: AH
authors.lastname: Porter
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Jacobsen
authors.forename: Corinna
authors.initials: C
authors.lastname: Koebnick
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D015535:Arthritis, Psoriatic / Q000188:drug therapy / Q000453:epidemiology / Q000208:ethnology; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003880:Dermatology; D057286:Electronic Health Records; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D010372:Pediatrics; D011237:Predictive Value of Tests; D015995:Prevalence; D011320:Primary Health Care; D011565:Psoriasis / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000208:ethnology*; D044469:Racial Groups / Q000706:statistics & numerical data*; D055815:Young Adult