BMC Public Health 2007, 7:45 http://www.biomedcentral.com/1471-2458/7/45 Conclusion In Sweden, levels of SA increased dramatically during the second half of the 1990s, and especially at the beginning of the 21st century; the rising cost of SA now threatens to undermine the welfare state. Efforts should continue to be made to reduce and prevent longer-term SA associated with poor health outcomes. We have shown that self-reported reduced working capacity due to a long-standing illness of more than 3 months is related to length of SA, even after taking several important confounders into consideration. The longer the SA taken, the more people reported longstanding illness and reduced working capacity. We also found that a large por- tion of those on SA ≥29 days had no self-reported reduced working capacity due to longstanding illness; however, some of the people in this group report other health prob- lems. It is also possible that some respondents had health problems not captured in the survey. Abbreviations CI = confidence interval, OR = odds ratio, SA = sickness absence, SES = socioeconomic status Competing interests The author(s) declare that they have no competing inter- ests. Authors' contributions KS conceived the idea for the study. JS, SEJ, and KS designed the study. JS and SEJ performed the statistical analysis. JS and SEJ drafted the manuscript. AAW and KS revised the manuscript. All authors read and approved the final manuscript. Acknowledgements This work was supported by grants from the National Institutes of Health (1 R01 HL71084-01), the Swedish Council for Working Life and Social Research (2001–2373), the Swedish Research Council (K2004-21X-11651- 09A and K2005-27X-15428-01A), the Knut and Alice Wallenberg Founda- tion, and the Stockholm County Council. These funding bodies played no role in the study design; the collection, analysis, and interpretation of data; the writing of the manuscript; or the decision to submit the manuscript for publication. We thank Kimberly Kane of the Center for Family and Com- munity Medicine for editing this text, and Sanna Sundquist at the University of California, San Francisco, for technical assistance. References 1. Eklund M, Jonasson B, Sunden A: Arbetsförhållanden – orsak till sjukskrivning? (Working conditions – the reason for sickness absence?). Stockholm, Sweden , Analyserar 2003:10, Riks- försäkringsverket (RFV), http://www.forsakringskassan.se; 2003. 2. Socialförsäkringens omfattning och finansiering 2003–2006. (Scope and financing of social insurance: 2003–2006.). Stock- holm, Sweden , Analyserar 2005:8, Försäkringskassan; 2005. 3. Redovisning av statistik, upplysningar om regler, rutiner och praxis. (Statistical report, information about rules, routines and practice. What is the cost of sickness absence in various occupations?). Stockholm, Sweden , 2003:5, Riksförsäkringsverket (RFV), http://www.forsakringskassan.se; 2003. 4. Marklund S, Palmer E, Hogstedt C, Bjurvald M, Theorell T: Den höga sjukfrånvaron - sanning och konsekvens. (High rates of sick- ness absence – truth and consequence). Stockholm, Sweden , Statens folklhälsoinstitut (Swedish National Institute of Public Health); 2004:362. 5. Söderström L, Ekbladh M, Rehn E: Vad sägar ekonomerna? En forskningsöversikt. Samtal om socialförsäkringen. (What do the economists say? An overview of research. Discussions About Social Insurance). Stockholm, Sweden , Socialförsäkringsu- tredningen, Nr 9, Statens Offentliga Utredningar, www.sou.gov.se/ socialforsakring. 6. Social Insurance: General Information about Social Insur- ance. Volume 2007. Stockholm, Sweden , Försäkringskassan, Elec- tronic source: http://www.forsakringskassan.se/sprak/eng/; 2007. 7. Larsson L: Sick of being unemployed? Interactions between unemployment and sickness insurance in Sweden. Uppsala, Sweden , Working Paper 2002: 6, Institute for Labour Market Policy Evaluation; 2002. 8. Wikman A, Marklund S, Alexanderson K: Illness, disease, and sick- ness absence: an empirical test of differences between con- cepts of ill health. J Epidemiol Community Health 2005, 59(6):450-454. 9. Kristensen TS: Sickness absence and work strain among Dan- ish slaughterhouse workers: an analysis of absence from work regarded as coping behaviour. Soc Sci Med 1991, 32(1):15-27. 10. Rael EG, Stansfeld SA, Shipley M, Head J, Feeney A, Marmot M: Sick- ness absence in the Whitehall II study, London: the role of social support and material problems. J Epidemiol Community Health 1995, 49(5):474-481. 11. Marmot M, Feeney A, Shipley M, North F, Syme SL: Sickness absence as a measure of health status and functioning: from the UK Whitehall II study. J Epidemiol Community Health 1995, 49(2):124-130. 12. Grossi G, Soares JJ, Angesleva J, Perski A: Psychosocial correlates of long-term sick-leave among patients with musculoskeletal pain. Pain 1999, 80(3):607-619. 13. Leigh JP: Employee and job attributes as predictors of absen- teeism in a national sample of workers: the importance of health and dangerous working conditions. Soc Sci Med 1991, 33(2):127-137. 14. Moreau M, Valente F, Mak R, Pelfrene E, de Smet P, De Backer G, Kornitzer M: Occupational stress and incidence of sick leave in the Belgian workforce: the Belstress study. J Epidemiol Commu- nity Health 2004, 58(6):507-516. 15. Morken T, Riise T, Moen B, Hauge SH, Holien S, Langedrag A, Peder- sen S, Saue IL, Seljebo GM, Thoppil V: Low back pain and wide- spread pain predict sickness absence among industrial workers. BMC Musculoskelet Disord 2003, 4:21. 16. Leijon M, Hensing G, Alexanderson K: Gender trends in sick-list- ing with musculoskeletal symptoms in a Swedish county dur- ing a period of rapid increase in sickness absence. Scand J Soc Med 1998, 26(3):204-213. 17. Shiels C, Gabbay MB, Ford FM: Patient factors associated with duration of certified sickness absence and transition to long- term incapacity. Br J Gen Pract 2004, 54(499):86-91. 18. Jzelenberg W, Molenaar D, Burdorf A: Different risk factors for musculoskeletal complaints and musculoskeletal sickness absence. Scand J Work Environ Health 2004, 30(1):56-63. 19. Statistics Sweden: The Swedish survey of living conditions. Design and method. Stockholm , Statistics Sweden; 1996:Appen- dix 16. 20. SAS Institute Inc: The SAS System, version 8. Cary, NC, USA , SAS Institute, Inc; 1999. 21. Alexanderson K, Arrelöv B, Hagberg J, Karlsryd E, Löfgren A, Ponzer S: Läkarens arbete med sjukskrivning- en enkätstudie. (Phy- sician’s work with sick listing – a questionnaire study). Swe- den , Swedish Social Insurance Agency, Karolinska Institute, Stockholm County Council, and Östergötland County Council; 2005. 22. Carne S: Sick absence certification. Analysis of one group practice in 1967. Br Med J 1969, 1(5637):147-149. 23. Handfield-Jones RP: Who Shall Help The Doctor?Ancillaries, Prescriptions, And Certificates. Lancet 1964, 14:1173-1174. 24. Englund L, Svardsudd K: Sick-listing habits among general prac- titioners in a Swedish county. Scand J Prim Health Care 2000, 18(2):81-86. Page 10 of 11 (page number not for citation purposes)