title: Differences in the ICD-10 diagnostic subtype of depression in bipolar disorder compared to recurrent depressive disorder.
abstract: BACKGROUND
  The aim of the study was to investigate whether patients with bipolar depression and patients with recurrent depressive disorder present with different subtypes of depressive episode as according to ICD-10.
  
  
  METHODS
  All patients who got a diagnosis of bipolar affective disorder, current episode of depression, or a diagnosis of recurrent depressive disorder, current episode of depression, in a period from 1994 to 2002 at the first outpatient treatment or at the first discharge from psychiatric hospitalization in Denmark were identified in a nationwide register.
  
  
  RESULTS
  Totally, 389 patients got a diagnosis of bipolar disorder, current episode of depression, and 5.391 patients got a diagnosis of recurrent depressive disorder, current episode of depression, at first contact. Compared with patients with a diagnosis of recurrent depressive disorder, patients with bipolar disorder, current episode of depression, were significantly less often outpatients (49.4 vs. 68.0%), significantly more often got a diagnosis of severe depression (42.7 vs. 23.3%) or a diagnosis of depression with psychotic symptoms (14.9 vs. 7.2%). The rate of subsequent hospitalization was increased for patients with bipolar disorder, current episode of depression, compared with patients with a current depression as part of a recurrent depressive disorder (HR = 1.50, 95% CI = 1.20-1.86).
  
  
  CONCLUSIONS
  The results consistently indicate that a depressive episode is severer and/or more often associated with psychotic symptoms when it occurs as part of a bipolar disorder than as part of a recurrent depressive disorder.
authors.affiliation: Department of Psychiatry, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark. lars.kessing@rh.dk
authors.forename: Lars Vedel
authors.initials: LV
authors.lastname: Kessing
authors.forename: Hans Mørch
authors.initials: HM
authors.lastname: Jensen
authors.forename: Ellen Margrethe
authors.initials: EM
authors.lastname: Christensen
mesh_terms: D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data; D001714:Bipolar Disorder / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D015897:Comorbidity; D003718:Denmark; D003866:Depressive Disorder / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D011379:Prognosis; D011618:Psychotic Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D012008:Recurrence; D013001:Somatoform Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D019966:Substance-Related Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology