a1 Medical Research Council (MRC) Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, UK
a2 Rheinische Friedrich-Wilhelms-Universität Bonn, Germany
a3 Central Institute of Mental Health, Division of Genetic Epidemiology in Psychiatry, Mannheim, Germany
a4 Laboratory of Psychiatric Genetics, Department of Psychiatry, Poznan University of Medical Sciences, Poland
a5 Institute of Public Health, Ljubljana, Slovenia
a6 Aarhus University Hospital, Risskov, Denmark
a7 Croatian Institute for Brain Research, Medical School, University of Zagreb, Croatia
a8 Biological Psychiatry Unit and Dual Diagnosis Ward IRCCS, Centro San Giovanni di Dio, FBF, Brescia, Italy
a9 Free University of Brussels, Department of Psychiatry, Belgium
a10 Department of Psychiatry, Nijmegen, The Netherlands
a11 Division of Psychological Medicine and Psychiatry, Institute of Psychiatry, King's College London, UK
Background A number of scales are used to estimate the severity of depression. However, differences between self-report and clinician rating, multi-dimensionality and different weighting of individual symptoms in summed scores may affect the validity of measurement. In this study we examined and integrated the psychometric properties of three commonly used rating scales.
Method The 17-item Hamilton Depression Rating Scale (HAMD-17), the Montgomery–Asberg Depression Rating Scale (MADRS) and the Beck Depression Inventory (BDI) were administered to 660 adult patients with unipolar depression in a multi-centre pharmacogenetic study. Item response theory (IRT) and factor analysis were used to evaluate their psychometric properties and estimate true depression severity, as well as to group items and derive factor scores.
Results The MADRS and the BDI provide internally consistent but mutually distinct estimates of depression severity. The HAMD-17 is not internally consistent and contains several items less suitable for out-patients. Factor analyses indicated a dominant depression factor. A model comprising three dimensions, namely ‘observed mood and anxiety’, ‘cognitive’ and ‘neurovegetative’, provided a more detailed description of depression severity.
Conclusions The MADRS and the BDI can be recommended as complementary measures of depression severity. The three factor scores are proposed for external validation.
(Received June 14 2007)
(Revised July 20 2007)
(Accepted July 20 2007)
(Online publication October 09 2007)