title: The prevalence and burden of subthreshold generalized anxiety disorder: a systematic review.
abstract: BACKGROUND
  To review the prevalence and impact of generalized anxiety disorder (GAD) below the diagnostic threshold and explore its treatment needs in times of scarce healthcare resources.
  
  
  METHODS
  A systematic literature search was conducted until January 2013 using PUBMED/MEDLINE, PSYCINFO, EMBASE and reference lists to identify epidemiological studies of subthreshold GAD, i.e. GAD symptoms that do not reach the current thresholds of DSM-III-R, DSM-IV or ICD-10. Quality of all included studies was assessed and median prevalences of subthreshold GAD were calculated for different subpopulations.
  
  
  RESULTS
  Inclusion criteria led to 15 high-quality and 3 low-quality epidemiological studies with a total of 48,214 participants being reviewed. Whilst GAD proved to be a common mental health disorder, the prevalence for subthreshold GAD was twice that for the full syndrome. Subthreshold GAD is typically persistent, causing considerably more suffering and impairment in psychosocial and work functioning, benzodiazepine and primary health care use, than in non-anxious individuals. Subthreshold GAD can also increase the risk of onset and worsen the course of a range of comorbid mental health, pain and somatic disorders; further increasing costs. Results are robust against bias due to low study quality.
  
  
  CONCLUSIONS
  Subthreshold GAD is a common, recurrent and impairing disease with verifiable morbidity that claims significant healthcare resources. As such, it should receive additional research and clinical attention.
authors.forename: Heidemarie
authors.initials: H
authors.lastname: Haller
authors.forename: Holger
authors.initials: H
authors.lastname: Cramer
authors.forename: Romy
authors.initials: R
authors.lastname: Lauche
authors.forename: Florian
authors.initials: F
authors.lastname: Gass
authors.affiliation: Department of Internal and Integrative Medicine, Kliniken Essen-Mitte, Faculty of Medicine, University Duisburg-Essen, Am Deimelsberg 34a, 45276 Essen, Germany. gustav.dobos@uni-essen.de.
authors.forename: Gustav J
authors.initials: GJ
authors.lastname: Dobos
mesh_terms: D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000188:drug therapy* / Q000453:epidemiology*; D015897:Comorbidity; D017281:Cost of Illness; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D015995:Prevalence; D011320:Primary Health Care / Q000191:economics