title: The Bipolar Depression Rating Scale (BDRS): its development, validation and utility.
abstract: OBJECTIVE
  Unipolar and bipolar depression differ neurobiologically and in clinical presentation. Existing depression rating instruments, used in bipolar depression, fail to capture the necessary phenomenological nuances, as they are based on and skewed towards the characteristics of unipolar depression. Both clinically and in research there is a growing need for a new observer-rated scale that is specifically designed to assess bipolar depression.
  
  
  METHODS
  An instrument reflecting the characteristics of bipolar depression was drafted by the authors, and administered to 122 participants aged 18-65 (44 males and 78 females) with a diagnosis of DSM-IV bipolar disorder, who were currently experiencing symptoms of depression. The Bipolar Depression Rating Scale (BDRS) was administered together with the Hamilton Depression Rating Scale (HAM-D), Montgomery Asberg Depression Rating Scale (MADRS) and Young Mania Rating Scale (YMRS).
  
  
  RESULTS
  The BDRS has strong internal consistency (Cronbach's alpha = 0.917), and robust correlation coefficients with the MADRS (r = 0.906) and HAM-D (r = 0.744), and the mixed subscale correlated with the YMRS (r = 0.757). Exploratory factor analysis showed a three-factor solution gave the best account of the data. These factors corresponded to depression (somatic), depression (psychological) and mixed symptom clusters.
  
  
  CONCLUSIONS
  This study provides evidence for the validity of the BDRS for the measurement of depression in bipolar disorder. These results suggest good internal validity, provisional evidence of inter-rater reliability and strong correlations with other depression rating scales.
authors.affiliation: Barwon Health and the Geelong Clinic, Geelong; Department of Clinical and Biomedical Sciences, University of Melbourne; and Orygen Research Centre, Melbourne, Victoria, Australia. mikebe@barwonhealth.org.au
authors.forename: Michael
authors.initials: M
authors.lastname: Berk
authors.forename: Gin S
authors.initials: GS
authors.lastname: Malhi
authors.forename: Catherine
authors.initials: C
authors.lastname: Cahill
authors.forename: A Catherine
authors.initials: AC
authors.lastname: Carman
authors.forename: Dusan
authors.initials: D
authors.lastname: Hadzi-Pavlovic
authors.forename: Mary T
authors.initials: MT
authors.lastname: Hawkins
authors.forename: Mauricio
authors.initials: M
authors.lastname: Tohen
authors.forename: Philip B
authors.initials: PB
authors.lastname: Mitchell
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000503:physiopathology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index