Persistent smoking as a predictor of disability pension due to musculoskeletal diagnoses: A 23year prospective study of Finnish twins Annina Ropponen a, ⁎, Tellervo Korhonen b , Pia Svedberg c , Markku Koskenvuo b , Karri Silventoinen d , Jaakko Kaprio b,e,f a Finnish Institute of Occupational Health, Helsinki, Finland b Department of Public Health, University of Helsinki, Finland c Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden d Population Research Unit, Department of Sociology, University of Helsinki, Finland e Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Finland f Institute for Molecular Medicine, University of Helsinki, Finland abstract article info Available online xxxx Keywords: Sickness absence Disability pension Musculoskeletal disorders Smoking Prospective design Objective. To investigate whether stability or changes in smoking predict disability pension (DP) due to low back diagnoses (LBD) and musculoskeletal diagnoses (MSD) after taking familial confounding into account using a co-twin design. Method. Longitudinal smoking patterns and multiple covariates in a population-based cohort of 17,451 Finnish twins (6959 complete pairs) born before 1958 were surveyed through questionnaires in 1975 and 1981. The outcome data were collected from the national pension registers until the end of 2004. Cox proportional hazards regression models were used for statistical analyses. Results. Disability pension due to low back diagnoses was granted to 408 individuals and disability pension due to musculoskeletal diagnoses to 1177 individuals during the follow-up of 23 years. Being a persistent smoker (current smoker both 1975 and 1981) predicted a significantly increased risk for disability pension (hazard ratio 1.69, 95% confidence interval 1.46, 1.97) compared to those individuals who had never smoked. The association remained when several confounding factors, including familial factors, were taken into account. Conclusion. Persistent smoking predicts early disability pension due to musculoskeletal diagnoses and low back diagnoses independently from numerous confounding factors, including familial effects shared by the co- twins. © 2013 Elsevier Inc. All rights reserved. Introduction Smoking is a major preventable cause of death (WHO, 2012), and also clearly associated with chronic conditions including musculoskeletal disorders (MSD) (Battie et al., 1991; Brook et al., 2012; Malaise et al., 2012). Smoking can be causally associated with disability pension (DP), for example because of the adverse health effects of smoking related to underlying chronic conditions (MSD) (Karlson and Deane, 2012; Shiri et al., 2010), but the association can be also because of confounding factors, such as low socioeconomic status (Pietikäinen et al., 2011); these different mechanisms can also affect the associations with DP together (Haukenes et al., 2013). Both smoking and MSD incur considerable costs to society, but even more if they lead to an award of a DP. Despite the link between smoking and DP, their relationships, in particular DP due to MSD have been rarely studied. At present, smoking has been mainly studied as a risk factor for DP in general, not accounting for diagnosis group. Furthermore, these studies have had at least one of the following limitations: examined only in men (Neovius et al., 2010) or women (Friis et al., 2008), short follow-up time 10 years or less, or only one occupation or living area (Claessen et al., 2010; Friis et al., 2008; Husemoen et al., 2004). The previous reports specifically aimed at investigating DP due to MSD have been based on Nordic twin cohorts (Pietikäinen et al., 2011; Ropponen et al., 2011a,b) and have pointed in the direction that smoking might be an early predictor for individuals at risk for DP due to MSD. Some indications also exist that the risk associated with smoking might vary between different diagnosis groups leading to a DP grant. Furthermore, assessment of smoking patterns between two time points located 25 years apart in Swedish twins showed that being a persistent tobacco user predicted both DP in general and DP due to MSD in an 8 year follow-up (Ropponen et al., 2011a). Smoking is only one aspect of health behavior and different health behaviors are known to be mutually related. For example, smoking cessation may be promoted by a motivation to improve one's fitness level due to increased body weight or conversely smoking may be used to control excess weight gain (Farley et al., 2012; Yong and Preventive Medicine xxx (2013) xxx–xxx ⁎ Corresponding author at: Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, 00250 Helsinki, Finland. Fax: +358 30 474 2008. E-mail address: annina.ropponen@ttl.fi (A. Ropponen). YPMED-03757; No. of pages: 5; 4C: 0091-7435/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ypmed.2013.10.001 Contents lists available at ScienceDirect Preventive Medicine journal homepage: www.elsevier.com/locate/ypmed Please cite this article as: Ropponen, A., et al., Persistent smoking as a predictor of disability pension due to musculoskeletal diagnoses: A 23 year prospective study of Finnish twins, Prev. Med. (2013), http://dx.doi.org/10.1016/j.ypmed.2013.10.001