title: Increased risk of lichen simplex chronicus in people with anxiety disorder: a nationwide population-based retrospective cohort study.
abstract: BACKGROUND
  The cingulate cortex is the main area in the brain involved in pruritus processing and is deactivated after scratching. Lichen simplex chronicus (LSC) is a common pruritic skin disorder characterized by skin lichenification following excessive scratching. Psychological factors may contribute to both the development and persistence of LSC.
  
  
  OBJECTIVE
  To estimate the hazard ratio (HR) of LSC in people with anxiety disorders compared with the general population.
  
  
  METHODS
  In this nationwide population-based retrospective cohort study we identified a total of 69 386 people, who formed the anxiety cohort, by using the Taiwan National Health Insurance Research Database from 2000 to 2009. The comparison cohort was composed of randomly selected people frequency matched for age (within 5-year intervals), sex and index date (the date of anxiety diagnosis) based on a 1 : 2 ratio. The risk of LSC was estimated as HRs and 95% confidence intervals (CIs) using the Cox proportional hazards model.
  
  
  RESULTS
  After adjusting for age, sex and LSC-associated comorbidities, the people with anxiety had a 1·41-fold greater risk of developing LSC compared with the people in the comparison cohort (HR 1·41, 95% CI 1·30-1·52, P < 0·0001). In particular, individuals with obsessive-compulsive disorder had a significantly increased risk of developing LSC (HR 1·72, 95% CI 1·03-2·88, P = 0·0395).
  
  
  CONCLUSIONS
  This study demonstrates that having an anxiety disorder is associated with an increased risk of LSC. Psychological factors were found to contribute to LSC. We recommend combining the management of LSC and psychological disorders to achieve favourable outcomes.
authors.affiliation: Department of Radiology, China Medical University Hospital, No. 2 Yuh-Der Road, Taichung, 404, Taiwan; Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University Hospital, No. 2 Yuh-Der Road, Taichung, 404, Taiwan.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Liao
authors.forename: C-C
authors.initials: CC
authors.lastname: Lin
authors.forename: P-P
authors.initials: PP
authors.lastname: Tsai
authors.forename: W-C
authors.initials: WC
authors.lastname: Shen
authors.forename: F-C
authors.initials: FC
authors.lastname: Sung
authors.forename: C-H
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D001008:Anxiety Disorders / Q000150:complications* / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009450:Neurodermatitis / Q000453:epidemiology / Q000523:psychology*; D017678:Sex Distribution; D013624:Taiwan / Q000453:epidemiology