title: Classification of bipolar disorder in psychiatric hospital. A prospective cohort study.
abstract: BACKGROUND
  This study has explored the classification of bipolar disorder in psychiatric hospital. A review of the literature reveals that there is a need for studies using stringent methodological approaches.
  
  
  METHODS
  480 first-time admitted patients to psychiatric hospital were found eligible and 271 of these gave written informed consent. The study sample was comprised of 250 patients (52%) with hospital diagnoses. For the study, expert diagnoses were given on the basis of a structured diagnostic interview (M.I.N.I.PLUS) and retrospective review of patient records.
  
  
  RESULTS
  Agreement between the expert's and the clinicians' diagnoses was estimated using Cohen's kappa statistics. 76% of the primary diagnoses given by the expert were in the affective spectrum. Agreement concerning these disorders was moderate (kappa ranging from 0.41 to 0.47). Of 58 patients with bipolar disorder, only 17 received this diagnosis in the clinic. Almost all patients with a current manic episode were classified as currently manic by the clinicians. Forty percent diagnosed as bipolar by the expert, received a diagnosis of unipolar depression by the clinician. Fifteen patients (26%) were not given a diagnosis of affective disorder at all.
  
  
  CONCLUSIONS
  Our results indicate a considerable misclassification of bipolar disorder in psychiatric hospital, mainly in patients currently depressed. The importance of correctly diagnosing bipolar disorder should be emphasized both for clinical, administrative and research purposes. The findings questions the validity of psychiatric case registers. There are potential benefits in structuring the diagnostic process better in the clinic.
authors.affiliation: Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, and Division of general psychiatry, Nordland Hospital, Bodø, Norway. terje.oiesvold@nlsh.no
authors.forename: Terje
authors.initials: T
authors.lastname: Øiesvold
authors.forename: Mary
authors.initials: M
authors.lastname: Nivison
authors.forename: Vidje
authors.initials: V
authors.lastname: Hansen
authors.forename: Knut W
authors.initials: KW
authors.lastname: Sørgaard
authors.forename: Line
authors.initials: L
authors.lastname: Østensen
authors.forename: Ingunn
authors.initials: I
authors.lastname: Skre
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000145:classification* / Q000175:diagnosis*; D015331:Cohort Studies; D003866:Depressive Disorder / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006760:Hospitalization; D006778:Hospitals, Psychiatric; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results