title: A review identifies and classifies reasons for ordering diagnostic tests.
abstract: OBJECTIVE
  To consider the reasons and context for test ordering by doctors when faced with an undiagnosed complaint in primary or secondary care.
  
  
  METHODS
  We reviewed any study of any design that discussed factors that may affect a doctor's decision to order a test. Articles were located through searches of electronic databases, authors' files on diagnostic methodology, and reference lists of relevant studies. We extracted data on: study design, type of analysis, setting, topic area, and any factors reported to influence test ordering.
  
  
  RESULTS
  We included 37 studies. We carried out a thematic analysis to synthesize data. Five key groupings arose from this process: diagnostic factors, therapeutic and prognostic factors, patient-related factors, doctor-related factors, and policy and organization-related factors. To illustrate how the various factors identified may influence test ordering we considered the symptom low back pain and the diagnosis multiple sclerosis as examples.
  
  
  CONCLUSIONS
  A wide variety of factors influence a doctor's decision to order a test. These are integral to understanding diagnosis in clinical practice. Traditional diagnostic accuracy studies should be supplemented with research into the broader context in which doctors perform their work.
authors: MRC Health Services Research Collaboration, Department of Social Medicine, Canynge Hall, Whiteladies Road, Bristol BS8 2PR, UK.
authors: Penny
authors: P
authors: Whiting
authors: Merran
authors: M
authors: Toerien
authors: Isabel
authors: I
authors: de Salis
authors: Jonathan A C
authors: JA
authors: Sterne
authors: Paul
authors: P
authors: Dieppe
authors: Matthias
authors: M
authors: Egger
authors: Tom
authors: T
authors: Fahey
mesh_terms: D001291:Attitude of Health Personnel; D003657:Decision Making; D003695:Delivery of Health Care / Q000379:methods*; D003954:Diagnostic Services; D006801:Humans; D017116:Low Back Pain / Q000209:etiology; D009103:Multiple Sclerosis / Q000175:diagnosis; D010818:Practice Patterns, Physicians'; D011379:Prognosis