title: Laboratory tests and identified diagnoses in patients with physical and chronic urticaria and angioedema: A systematic review.
abstract: BACKGROUND
  The value of laboratory tests in chronic urticaria is still controversial.
  
  
  OBJECTIVE
  Our aim was to assess this value in clinical studies, and to identify factors explaining the variation in the number of identified causes.
  
  
  METHODS
  A total of 4 electronic databases were searched, and a manual literature search was performed. Only unselected patient series with more than 50 adult patients were included. From each included study predefined items were recorded to assess their quality (consecutive patients, use of standardized diagnostic criteria) and validity (follow-up, assessment of treatment effects, level of evidence).
  
  
  RESULTS
  A total of 29 studies were included, involving 6462 patients. The verification of the validity of the results and the level of evidence of the included studies were limited.
  
  
  CONCLUSIONS
  No relationship between the number of identified diagnoses and the number of performed laboratory tests, the different settings, the study design, or the publication period was found. On the basis of this systematic review and the relevant literature, a clinical guideline in the form of a flowchart is presented.
authors.affiliation: Department of Dermatology, Academic Medical Center, University of Amsterdam, The Netherlands.
authors.forename: Martina M A
authors.initials: MM
authors.lastname: Kozel
authors.forename: Patrick M M
authors.initials: PM
authors.lastname: Bossuyt
authors.forename: Jan R
authors.initials: JR
authors.lastname: Mekkes
authors.forename: Jan D
authors.initials: JD
authors.lastname: Bos
mesh_terms: D000799:Angioedema / Q000175:diagnosis*; D002908:Chronic Disease; D019411:Clinical Laboratory Techniques; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity; D014581:Urticaria / Q000175:diagnosis*