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Abstract Musculoskeletal disorders account for a higher proportion of sickness absence from work in the European Union than any other health condition. The present study examined the associations between work environment, dispositional optimism/pessimism and medically certified sickness absence caused by musculoskeletal complaints in a sample of employees from the Norwegian Armed Forces (N = 1190, 77.5% men). Dispositional pessimism, but not optimism, predicted the amount of absence also when taking into account the effects of age and the work environment. Overall, our results support previous studies suggesting that pessimism is a more salient predictor of physical health than optimism. Our results also suggest that it may be beneficial for employers to combine medical treatment of musculoskeletal symptoms with psychological treatment targeting pessimistic outcome expectancies in order to reduce the amount of sickness absence.

Introduction Musculoskeletal disorders (MSD) account for a higher proportion of sickness absence from work in the European Union than any other health condition (Bevan et al., 2009; Edwards & Greasley, 2010). The etiology of MSD is considered to be multidimensional and includes biomechanical risk factors, psychosocial workplace factors, and individual characteristics. For example, biomechanical risk factors like repetitive work and working in a static posture have been shown to predict musculoskeletal symptoms in a large variety of occupational groups (Bernard, 1997 and van der Windt et al., 2000). Reviews on the impact of psychosocial factors have demonstrated that employees’ perceptions of job control, job demands, and social support from colleagues and supervisors are important in relation to musculoskeletal complaints (e.g., Ariëns et al., 2001 and Bongers et al., 2002). The evidence from these reviews suggests that higher demands at work, less control over work, and lower support at work independently or in combination predict a wide variety of complaints, including neck pain and upper extremity symptoms. Alongside mental disorders, MSD are also one of the top causes of inflows into disability, with the majority caused by long-term absences (Organisation for Economic Co-operation and Development [OECD], 2009). MSD are thus not only a major burden for the individual, they also represent a substantial economical cost for society as a whole. It is estimated that OECD countries on average spend two percent of their gross domestic product (GDP) on sickness absence and disability benefits. In Norway, this estimate is even higher, with expenditures close to five percent of GDP, highest among all Member States (OECD, 2009). Identifying factors related to absence caused by musculoskeletal complaints can therefore have huge benefits for both the individual and society at large. 1.1. Dispositional optimism and pessimism The aim of the present study was to examine dispositional optimism/pessimism as possible individual characteristics affecting sickness absence caused by musculoskeletal complaints. Dispositional optimism and pessimism can be defined as, respectively, generalized positive and negative outcome expectancies that are relatively stable across time and situations (Scheier & Carver, 1985). Optimistic individuals generally hold positive expectations regarding the future and expect good things to happen to them. Pessimism, on the other hand, indicates a tendency to believe that generally bad things will happen to you in life across a wide variety of settings. Both optimism and pessimism have been found to be associated with a broad range of health outcomes. Optimism has been found to predict rapid recovery from surgery (Chamberlain, Petrie, & Azariah, 1992), adaption to chronic disease (Fournier, de Ridder, & Bensing, 2002), and better survival among cancer patients (Allison, Guichard, Fung, & Gilain, 2003), while a pessimistic life orientation has been shown to be a significant risk factor for mortality among cancer patients (Schulz, Bookwala, Knapp, Scheier, & Williamson, 1996) and physical illness among university students (Jackson, Sellers, & Peterson, 2002). The beneficial effects of optimism on health result in part because optimistic individuals employ more adaptive coping strategies and attract supportive social relationships (Carver et al., 2010 and Solberg Nes and Segerstrom, 2006). The positive expectancies of optimists lead to engagement and goal-directed efforts, and studies have found optimism to be associated with more approach and problem-oriented coping strategies (for a review, see Solberg Nes and Segerstrom (2006)). People who are doubtful in regard to goal-attainment (i.e., pessimistic) tend to give up or try to escape adversity by wishful thinking and other temporary distractions. Moreover, results from a meta-analytic review suggest that optimists are more flexible in their coping strategies and tend to use strategies that match the demands of the situation (e.g., more emotion-focused coping for traumas and more problem-oriented coping for academic stressors; Solberg Nes & Segerstrom, 2006). In work settings, the effect of optimism and pessimism on health may also be indirect through individuals’ perceptions of subjective work environment factors. Individual differences in pessimism/optimism may influence the degree to which people experience their work as demanding and uncontrollable, as well as how they relate to co-workers and supervisors. These experiences are in turn related to health outcomes (e.g., Ariëns et al., 2001). 1.2. Research aim and hypotheses Although several studies have investigated the association between optimism and quality of life among individuals suffering from chronic MSD (e.g., Brenes et al., 2002, Fournier et al., 2002 and Long and Sangster, 1993), little is known about the relationships between optimism/pessimism and sickness absence caused by musculoskeletal complaints. Based on the discussion presented above we propose that optimism and pessimism affect the amount of sickness absence caused by musculoskeletal symptoms. Specifically, the following hypotheses were tested:

3. Results We conducted preliminary analyses to examine the relationships between gender and the variables under investigation. A summary of descriptive statistics and correlations among all variables separately for men and women is provided in Table 1. Men reported significantly higher amounts of work load (t[1188] = 2.987, p = .003), job control (t[1188] = 2.024, p = .043), and ergonomic (t[495.98] = 3.247, p = .001) and environmental (t[477.05] = 4.761, p < .001) demands. Women were on average older (t[400.277] = −4.640, p < .001) and had more sickness absence than men (t[408.928] = −3.194, p = .002). The mean untransformed sickness absence in days was 24.68 (SD = 38.01) for men and 33.12 (SD = 44.38) for women. Table 1. Descriptive statistics and intercorrelations among study variables for men (n = 922) and women (n = 268). Men Women Variable M SD M SD 1 2 3 4 5 6 7 8 9 10 1. Age 40.84 10.49 44.52b 11.69 — .08 .00 .05 -.07 .02 −.19⁎⁎ .13⁎ .04 .11 2. Work load 2.37 0.72 2.22b 0.75 −.01 — −.35⁎⁎ .04 −.03 .23⁎⁎ .15⁎ .01 .03 .09 3. Job control 2.59 0.63 2.50a 0.67 .10⁎⁎ −.31⁎⁎ — .55⁎⁎ .24⁎⁎ −.19⁎⁎ −.09 .08 −.14⁎ −.13⁎ 4. Positive stimulation 2.81 0.72 2.80 0.75 .01 .01 .51⁎⁎ — .50⁎⁎ −.11 −.07 .19⁎⁎ −.19⁎⁎ −.07 5. Relationship with supervisor 2.61 0.79 2.61 0.87 −.01 −.04 .32⁎⁎ .59⁎⁎ — −.09 .01 .02 −.11 −.05 6. Ergonomic demands 1.57 0.63 1.45b 0.54 −.08⁎ .12⁎⁎ −.23⁎⁎ −.20⁎⁎ −.17⁎⁎ — .41⁎⁎ −.06 .14⁎ .19⁎⁎ 7. Environmental demands 1.57 0.78 1.33b 0.70 −.24⁎⁎ −.01 −.16⁎⁎ −.05 −.04 .48⁎⁎ — −.03 .12 −.10 8. Optimism 3.54 0.62 3.60 0.66 −.02 −.11⁎⁎ .18⁎⁎ .27⁎⁎ .19⁎⁎ −.09⁎⁎ −.03 — −.47⁎⁎ .00 9. Pessimism 2.19 0.74 2.29 0.82 .03 .04 −.18⁎⁎ −.34⁎⁎ −.28⁎⁎ .24⁎⁎ .07⁎ −.40⁎⁎ — .21⁎⁎ 10. Sickness absencea 1.09 0.49 1.21b 0.53 .12⁎⁎ −.03 −.02 −.05 −.05 .14⁎⁎ .04 −.04 .10⁎⁎ — Note. Coefficients are presented below the diagonal for men and above the diagonal for women. Statistically significant differences in means between men and women are indicated by a(p < .05) and b(p < .01). a Logarithmically transformed sickness absence. ⁎ p < .05. ⁎⁎ p < .01. Table options Given that we found gender differences in sickness absence and some of the work environment variables, we examined separate mediation models for men and women. The first set of models assessed the direct effect of optimism on sickness absence, as well as the indirect effects via the psychosocial work environment variables. The next set of models repeated these analyses with pessimism as independent variable. In all instances age and ergonomic and environmental demands were entered as covariates. For optimism, no direct or indirect effects were found for either men or women. As expected, optimism influenced perceptions of the psychosocial work environment, but there were no significant relationships between the proposed mediators and sickness absence. The only significant predictors of absence in these two models were age (B = 0.01, p < .001) and ergonomic demands (B = 0.12, p < .001) for men, and ergonomic (B = 0.24, p < .001) and environmental demands for women (B = −0.15, p = .003). No indirect effects were found in the analyses with pessimism as predictor either. However, as can be seen in Fig. 1, pessimism had significant direct effects on sickness absence in these models. After controlling for age and the physical work environment, pessimism was associated with more sickness absence for both men and women. The c’ path in Fig. 1 also shows that when the effects of the proposed mediator variables were partialled out, the coefficient for men fell just outside of conventional levels of statistical significance (p = .057). We used the procedure available in Brame, Paternoster, Mazerolle, and Piquero (1998) to determine whether the coefficient for men differed significantly from the coefficient for women. The resultant z-statistic was 1.733 which is not significant at p < .05. A multiple mediation model of dispositional pessimism and sickness absence ... Fig. 1. A multiple mediation model of dispositional pessimism and sickness absence through psychosocial work-environment. Unstandardized coefficients are given along the paths, with coefficients for men outside parentheses and women inside parentheses; c is the total effect of pessimism on sickness absence corrected for the effects age and ergonomic and environmental demands, and c’ is the direct effect after also correcting for proposed mediators. R2men = .04∗∗∗. R2women = .12∗∗∗. ∗p < .05. ∗∗p < .01. ∗∗∗p < .001. †p < .10.