title: The relative responsiveness of test instruments can be estimated using a meta-analytic approach: an illustration with treatments for depression.
abstract: We present a meta-analytic method that combines information on treatment effects from different instruments from a network of randomized trials to estimate instrument relative responsiveness.
  
  
  
  Five depression-test instruments [Beck Depression Inventory (BDI I/II), Patient Health Questionnaire (PHQ9), Hamilton Rating for Depression 17 and 24 items, Montgomery-Asberg Depression Rating] and three generic quality of life measures [EuroQoL (EQ-5D), SF36 mental component summary (SF36 MCS), and physical component summary (SF36 PCS)] were compared. Randomized trials of treatments for depression reporting outcomes on any two or more of these instruments were identified. Information on the within-trial ratios of standardized treatment effects was pooled across the studies to estimate relative responsiveness.
  
  
  
  The between-instrument ratios of standardized treatment effects vary across trials, with a coefficient of variation of 13% (95% credible interval: 6%, 25%). There were important differences between the depression measures, with PHQ9 being the most responsive instrument and BDI the least. Responsiveness of the EQ-5D and SF36 PCS was poor. SF36 MCS performed similarly to depression instruments.
  
  
  
  Information on relative responsiveness of several test instruments can be pooled across networks of trials reporting at least two outcomes, allowing comparison and ranking of test instruments that may never have been compared directly.
authors.affiliation: School of Social and Community Medicine, Faculty of Health Sciences, University of Bristol, 39 Whatley Road, Bristol BS8 2PS, UK. Electronic address: daphne.kounali@bristol.ac.uk.
authors.forename: Daphne Z
authors.initials: DZ
authors.lastname: Kounali
authors.affiliation: School of Social and Community Medicine, Faculty of Health Sciences, University of Bristol, 39 Whatley Road, Bristol BS8 2PS, UK; Department of Psychology, University of Bath, 6.19 Wessex House, Bath BA2 7AY, UK.
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Button
authors.affiliation: Division of Psychiatry, Faculty of Brain Sciences, School of Life and Medical Sciences, University College London, 67-73 Riding House St., London W1W 7EJ, UK.
authors.forename: Glyn
authors.initials: G
authors.lastname: Lewis
authors.affiliation: School of Social and Community Medicine, Faculty of Health Sciences, University of Bristol, 39 Whatley Road, Bristol BS8 2PS, UK.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Ades
mesh_terms: D003866:Depressive Disorder / Q000523:psychology* / Q000628:therapy*; D006801:Humans; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data*; D011788:Quality of Life / Q000523:psychology*; D016032:Randomized Controlled Trials as Topic; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
keywords: Depression; Effect sizes; Meta-Analysis; Ranking; Relative responsiveness; Test instruments