Estimating depression prevalence from the Beck Depression Inventory: is season of administration a moderator?

the ODIN group,; Michalak, Erin E.; Murray, Greg; Wilkinson, Clare; Dowrick, Chris; Lasa, Lourdes; Lehtinen, Ville; Dalgard, Odd Steffen; Ayuso-Mateos, Jose Luis; Vázquez-Barquero, Jose Luis; Casey, Patricia

doi:10.1016/j.psychres.2004.06.006

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Volume 129, Issue 1 , Pages 99-106, 30 November 2004

Estimating depression prevalence from the Beck Depression Inventory: is season of administration a moderator?

the ODIN group
- The ODIN group is composed of academic colleagues and research and administrative staff who have worked on this part of the project. They are Gail Birkbeck, Trygve Børve, Maura Costello, Pim Cuijpers, Ioana Davies, Graham Dunn, Nicholas Fenlon, Mette Finne, Fiona Ford, Andres Gomes del Barrio, Claire Hayes, Maggie Hendry, Ann Horgan, Tarja Koffert, Nicola Jones, Lourdes Lasa, Marja Lehtilä, Catherine McDonough, Christine Murphy, Anna Nevra, Teija Nummelin, Helen Page and Britta Sohlman.
Erin E. Michalak
- Corresponding author. Tel.: +1-604-822-7325; fax: +1-604-822-7922.
- Division of Mood Disorders, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, Canada V6T 2A1
Greg Murray
- School of Social and Behavioural Sciences, Swinburne University of Technology, John Street Hawthorn, P.O. Box 218, Hawthorn, 3122, Australia
Clare Wilkinson
- Division of General Practice, University of Wales College of Medicine, Wrexham, UK
Chris Dowrick
- Department of Primary Care, University of Liverpool, Liverpool, UK
Lourdes Lasa
- Clinical and Social Psychiatry Research Unit, Hospital de Laredo, University of Cantabria, Santander, Spain
Ville Lehtinen
- National Research and Development Centre for Welfare and Health, Mental Health Unit, Turku, Finland
Odd Steffen Dalgard
- Institute of General Practice and Community Medicine, University of Oslo, Oslo, Norway
Jose Luis Ayuso-Mateos
- Department of Psychiatry, Universidad Autonoma de Madrid and Hospital Universitario de la Princesa, Madrid, Spain
Jose Luis Vázquez-Barquero
- Clinical and Social Psychiatry Research Unit, Universidad de Cantabria and Marqués de Valdecilla University Hospital, Santander, Spain
Patricia Casey
- Mater Misericordiae Hospital, University College Dublin, Dublin, Ireland

Received 3 December 2003; received in revised form 29 March 2004; accepted 11 June 2004.

Abstract

The existence of winter seasonal affective disorder (SAD) and its milder population variants implies that depression estimates in a given population may tend to be higher in winter than at other times of the year. The aim of this study was therefore to test whether depression prevalence estimates based on the Beck Depression Inventory (BDI) are systematically moderated by season of administration. Existing information from the screening phase of a multicentre investigation of depression prevalence provided the data for the study. Repeated cross-sectional BDI data from samples in the United Kingdom (n=1299), Finland (n=1352), Norway (n=2711) and Spain (n=1246) were analysed for month- and season-of-administration effects. Whether data were measured continuously or as a dichotomous variable (BDI cutoff ≥13), there was no evidence of a systematic seasonal pattern in depression estimates across the four sites. No seasonal effects reached statistical significance at any single site, and trends in the association between winter and elevated BDI scores were positive in two sites (UK and Norway) and negative in two (Finland and Spain). Although limited by a post hoc analysis of existing data, this study provides the strongest evidence to date that season of administration is not a moderator of depression prevalence as estimated by the BDI.

Keywords: Depressive symptoms, Seasonality, Beck Depression Inventory