title: Minimal clinically important difference on the Beck Depression Inventory--II according to the patient's perspective.
abstract: BACKGROUND
  The Beck Depression Inventory, 2nd edition (BDI-II) is widely used in research on depression. However, the minimal clinically important difference (MCID) is unknown. MCID can be estimated in several ways. Here we take a patient-centred approach, anchoring the change on the BDI-II to the patient's global report of improvement.
  
  
  METHODS
  We used data collected (n = 1039) from three randomized controlled trials for the management of depression. Improvement on a 'global rating of change' question was compared with changes in BDI-II scores using general linear modelling to explore baseline dependency, assessing whether MCID is best measured in absolute terms (i.e. difference) or as percent reduction in scores from baseline (i.e. ratio), and receiver operator characteristics (ROC) to estimate MCID according to the optimal threshold above which individuals report feeling 'better'.
  
  
  RESULTS
  Improvement in BDI-II scores associated with reporting feeling 'better' depended on initial depression severity, and statistical modelling indicated that MCID is best measured on a ratio scale as a percentage reduction of score. We estimated a MCID of a 17.5% reduction in scores from baseline from ROC analyses. The corresponding estimate for individuals with longer duration depression who had not responded to antidepressants was higher at 32%.
  
  
  CONCLUSIONS
  MCID on the BDI-II is dependent on baseline severity, is best measured on a ratio scale, and the MCID for treatment-resistant depression is larger than that for more typical depression. This has important implications for clinical trials and practice.
authors.affiliation: School of Social and Community Medicine,University of Bristol,Bristol,UK.
authors.forename: K S
authors.initials: KS
authors.lastname: Button
authors.affiliation: School of Social and Community Medicine,University of Bristol,Bristol,UK.
authors.forename: D
authors.initials: D
authors.lastname: Kounali
authors.affiliation: School of Social and Community Medicine,University of Bristol,Bristol,UK.
authors.forename: L
authors.initials: L
authors.lastname: Thomas
authors.affiliation: School of Social and Community Medicine,University of Bristol,Bristol,UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Wiles
authors.affiliation: School of Clinical Sciences,University of Bristol,Bristol,UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Peters
authors.affiliation: School of Social and Community Medicine,University of Bristol,Bristol,UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Welton
authors.affiliation: School of Social and Community Medicine,University of Bristol,Bristol,UK.
authors.forename: A E
authors.initials: AE
authors.lastname: Ades
authors.affiliation: Division of Psychiatry,University College London,London,UK.
authors.forename: G
authors.initials: G
authors.lastname: Lewis
mesh_terms: D000328:Adult; D003863:Depression / Q000175:diagnosis* / Q000628:therapy; D003866:Depressive Disorder / Q000175:diagnosis* / Q000628:therapy; D061218:Depressive Disorder, Treatment-Resistant / Q000175:diagnosis / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000592:standards*; D011569:Psychiatric Status Rating Scales / Q000592:standards*; D011594:Psychometrics / Q000592:standards*; D016032:Randomized Controlled Trials as Topic; D012720:Severity of Illness Index
keywords: 2nd edition (BDI-II); Beck Depression Inventory; depression; minimal clinically important difference; outcome assessment; primary care