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Open Access Highly Accessed Research article

Classification of bipolar disorder in psychiatric hospital. a prospective cohort study

Terje Øiesvold1*, Mary Nivison2, Vidje Hansen3, Knut W Sørgaard45, Line Østensen5 and Ingunn Skre6

Author Affiliations

1 Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, and Division of general psychiatry, Nordland Hospital, Bodø, Norway

2 Clinic for substance abuse and specialized psychiatry, University Hospital of Northern Norway, Tromsø, Norway

3 Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, and Division of general psychiatry, University Hospital of Northern Norway, Tromsø, Norway

4 Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway

5 Division of General Psychiatry, Nordland Hospital, Bodø, Norway

6 Department of Psychology, Faculty of Health Science, University of Tromsø, Tromsø, Norway

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BMC Psychiatry 2012, 12:13  doi:10.1186/1471-244X-12-13

Published: 29 February 2012

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.