Do Psychosocial Working Conditions Modify the Effect of Depressive Symptoms on Long-Term Sickness Absence? Pernille U. Hjarsbech, MSc, 1 Karl Bang Christensen, PhD, 2 Rikke Voss Andersen, MSc, 3 Vilhelm Borg, PhD, 1 Birgit Aust, DrPH, 1 and Reiner Rugulies, PhD 1,4,5 Background The objective of this study was to investigate whether work unit-levels of psychosocial working conditions modify the effect of depressive symptoms on risk of long- term sickness absence (LTSA). Methods A total of 5,416 Danish female eldercare workers from 309 work units were surveyed using questionnaires assessing depressive symptoms and psychosocial working conditions. LTSA was derived from a national register. We aggregated scores of psychosocial working conditions to the work unit-level and conducted multi-level Poisson regression analyses. Results Depressive symptoms, but not psychosocial working conditions, predicted LTSA. Psychosocial working conditions did not statistically significantly modify the effect of depressive symptoms on LTSA. Conclusions Psychosocial working conditions did not modify the effect of depressive symptoms on LTSA. The results, however, need to be interpreted with caution, as we cannot rule out lack of exposure contrast and non-differential misclassification of the exposure. Am. J. Ind. Med. 56:1329–1340, 2013. ß 2013 Wiley Periodicals, Inc. KEY WORDS: psychosocial work environment; sickness absence; mental health; multi-level analysis; interaction INTRODUCTION Sickness absence have great cost for the individual and studies have found long-term sickness absence (LTSA) to be a strong predictor for both disability pensioning [Kivimäki et al., 2004; Lund et al., 2008] and mortality [Kivimäki et al., 2003; Vahtera et al., 2004]. Furthermore, the economic costs of LTSA put a strain on workplaces and the general social welfare system [Henderson et al., 2005; Ministry of Employment, 2008]. There is growing interest for mental health problems in working populations, as disability benefit claims and sickness absence due to mental health problems have increased in OECD countries [OECD, 2012]. Sickness absence has a multi-factorial etiology [Alexanderson and Norlund, 2004] and the International Classification of Functioning, Disability and Health (ICF) provides a bio-psychosocial model [World Health Organiza- tion (WHO), 2001] that is able to take the multidimensional 1 National Research Centre for theWorking Environment,Copenhagen,Denmark 2 Department of Biostatistics, Institute of Public Health, University of Copenhagen, Copenhagen,Denmark 3 COWIA/S,Esbjerg,Denmark 4 Department of Social Medicine, Institute of Public Health, University of Copenhagen, Copenhagen,Denmark 5 Departmentof Psychology,Universityof Copenhagen,Copenhagen,Denmark Contract grant sponsor: Danish Working Environment Research Fund; Contract grantnumber: 03-2008-09; Contractgrantsponsor:Danish Parliament (SATSpulje). Disclosure Statement:The authors report no conflicts of interests.  Correspondence to: Pernille U. Hjarsbech, MSc, National Research Centre for the Working Environment,Lersø Parkalle ´ 105,DK-2100Copenhagen,Denmark. E-mail:pmi @nrcwe.dk Accepted1July 2013 DOI10.1002/ajim.22230.Publishedonline 23 August2013 inWiley Online Library (wileyonlinelibrary.com). AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 56:1329–1340 (2013) ß 2013 Wiley Periodicals, Inc.