Triggers of sick leave : epidemiological studies of work-related factors

Sammanfattning: Background: In Sweden, the prerequisite for compensation during sick leave is a reduction of work ability due to disease or injury. Perhaps as a result of this, sick leave varies between individuals with the same diagnosis and over time in the population in a way that does not coincide with the variations in population health. This implies that to better understand the social phenomenon that is sick leave we need to look into other factors which may influence the association between disease, illness, sickness and sick leave. Aim: The main aim of this thesis was to identify and estimate the effect of factors at work which influence ill individuals to take sick leave. Methods: All four studies were based on data from the TUFS-project (an acronym in Swedish for “Triggers of sick leave”) which took place at six Swedish workplaces in health care, manufacturing industry, and white-collar office work between 2005 and 2007. A total of 1 430 employees (participation proportion 47%) answered a questionnaire at baseline and were subsequently followed with regard to sick leave for 3-12 months and interviewed during or shortly after taking sick leave. Study I used a cohort design assessing exposure at baseline with a longitudinal follow-up of sick leave, and Studies II-IV used a case-crossover design which included only individuals on sick leave, with each case serving as its’ own control. Exposure was measured in a telephone interview conducted during or shortly after sick leave. Results: In Study I an increased risk of future sick leave was found for individuals with a low level of adjustment latitude, whether measured as the general level of adjustment latitude or as having few different types of adjustment possibilities. This is in line with previous studies of adjustment latitude. However in Study II, the results indicated that many individuals had a stable pattern of exposure to lack of adjustment latitude. Among the 35% with variations in exposure during the two weeks prior to sick leave a decreased risk of sick leave was found on days when the participants were exposed to lack of adjustment latitude. In Study III an increased risk of sick leave was found when individuals had been exposed to problems in the relationship with colleagues or superiors the previous two workdays. Furthermore individuals were more likely to take sick leave when they expected a very stressful work situation during the following workday. In Study IV an increased risk of sick leave was found when the participants expected a lower workload than usual. Conclusion: A possible interpretation of the results from Studies I and II is that adjustment latitude both may capture long-lasting effects of a flexible work environment, and temporary possibilities to adjust work to being absent. The increased risks of sick leave found when having been exposed to problems in workplace relationships and when expecting a stressful work situation or a lower workload than usual (Studies III and IV) may function by lowering the threshold of reduced work ability at which an employee feel the need to take sick leave.