title: Towards a clinical staging for bipolar disorder: defining patient subtypes based on functional outcome.
abstract: BACKGROUND
  The functional outcome of Bipolar Disorder (BD) is highly variable. This variability has been attributed to multiple demographic, clinical and cognitive factors. The critical next step is to identify combinations of predictors that can be used to specify prognostic subtypes, thus providing a basis for a staging classification in BD.
  
  
  METHODS
  Latent Class Analysis was applied to multiple predictors of functional outcome in a sample of 106 remitted adults with BD.
  
  
  RESULTS
  We identified two subtypes of patients presenting "good" (n=50; 47.6%) and "poor" (n=56; 52.4%) outcome. Episode density, level of residual depressive symptoms, estimated verbal intelligence and inhibitory control emerged as the most significant predictors of subtype membership at the p<0.05 level. Their odds ratio (OR) and confidence interval (CI) with reference to the "good" outcome group were: episode density (OR=4.622, CI 1.592-13.418), level of residual depressive symptoms (OR=1.543, CI 1.210-1.969), estimated verbal intelligence (OR=0.969; CI 0.945-0.995), and inhibitory control (OR=0.771, CI 0.656-0.907). Age, age of onset and duration of illness were comparable between prognostic groups.
  
  
  CONCLUSIONS
  The longitudinal stability or evolution of the subtypes was not tested.
  
  
  CONCLUSIONS
  Our findings provide the first empirically derived staging classification of BD based on two underlying dimensions, one for illness severity and another for cognitive function. This approach can be further developed by expanding the dimensions included and testing the reproducibility and prospective prognostic value of the emerging classes. Developing a disease staging system for BD will allow individualised treatment planning for patients and selection of more homogeneous patient groups for research purposes.
authors.affiliation: Bipolar Disorders Program, Institute of Neurosciences, Hospital Clínic, University of Barcelona, IDIBAPS, CIBERSAM, Barcelona, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Reinares
authors.forename: Efstathios
authors.initials: E
authors.lastname: Papachristou
authors.forename: Philip
authors.initials: P
authors.lastname: Harvey
authors.forename: C
authors.initials: C
authors.lastname: Mar Bonnín
authors.forename: José
authors.initials: J
authors.lastname: Sánchez-Moreno
authors.forename: Carla
authors.initials: C
authors.lastname: Torrent
authors.forename: José L
authors.initials: JL
authors.lastname: Ayuso-Mateos
authors.forename: George B
authors.initials: GB
authors.lastname: Ploubidis
authors.forename: Eduard
authors.initials: E
authors.lastname: Vieta
authors.forename: Sophia
authors.initials: S
authors.lastname: Frangou
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D001714:Bipolar Disorder / Q000145:classification* / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011379:Prognosis; D012720:Severity of Illness Index