Occup Environ Med 2003;60(Suppl I):i71-i76Objectives: To investigate whether there is a relationship between fatigue and sickness absence. Two additional hypotheses were based on the theoretical distinction between involuntary, health related absence and voluntary, attitudinal absence. In the literature, the former term is usually used to describe long term sickness absence, the latter relates to short term sickness absence. In line with this, the first additional hypothesis was that higher fatigue would correspond with a higher risk of long term, primarily health related absence. The second additional hypothesis was that higher fatigue would correspond with a higher risk of short term, primarily motivational absence. Methods: A multidimensional fatigue measure, as well as potential sociodemographic and work related confounders were assessed in the baseline questionnaire of the Maastricht cohort study on fatigue at work. Sickness absence was objectively assessed on the basis of organisational absence records and measured over the six months immediately following the baseline questionnaire. In the first, general hypothesis the effect of fatigue on time-to-onset of first sickness absence spell during follow up was investigated. For this purpose, a survival analysis was performed. The effect of fatigue on long term sickness absence was tested by a logistic regression analysis. The effect of fatigue on short term sickness absence was investigated by performing a survival analysis with time-to-onset of first short absence spell as an outcome. Results: It was found that higher fatigue decreased the time-to-onset of the first sickness absence spell. Additional analyses showed that fatigue was related to long term as well as to short term sickness absence. The effect of fatigue on the first mentioned outcome was stronger than the effect on the latter outcome. Potential confounders only weakened the effect of fatigue on long term absence. Conclusions: Fatigue was associated with short term but particularly with long term sickness absence. The relation between fatigue and future sickness absence holds when controlling for work related and sociodemographic confounders. Fatigue as measured with the Checklist Individual Strength can be used as a screening instrument to assess the likelihood of sickness absence in the short term.S ickness absence is a complex phenomenon since its occurrence and course are influenced by a range of factors, including social factors (for example, social security system, health care, culture), work related factors (work content, work conditions), organisational factors (company size, the existence of health promotion programmes and absence policies) and individual factors (personality, health).

Little is known about the natural course of fatigue among employees. An adequate understanding of its development and risk factors is important to prevent chronic health complaints and absenteeism. This longitudinal study investigated associations between positive changes in perceived work characteristics (ie, a decrease in job demands, an increase in decision latitude, and an increase in social support) and changes in fatigue by performing hierarchical regression analyses. The work characteristics of the demand-control-support model were selected as predictors. The outcome measures emotional exhaustion and psychologic distress were investigated as secondary outcomes. The results showed that, compared with a stable work situation, positive changes in perceived social support, decision latitude, and psychologic job demands went together with a decrease in fatigue. Similar results were found for the secondary outcomes emotional exhaustion and psychologic distress.

The present study investigated work-related determinants of return to work. Our hypothesis was based on the strain hypothesis of the Demand-Control-Support model, which postulates a relation between job demands, job control and support at work on the one hand, and the aetiology of health complaints on the other hand. High demands were hypothesized to obstruct return to work, whereas high control and high support were thought to have a positive effect on return to work. This hypothesis was tested in a population of employees who were sick-listed for 6-8 weeks. Return to work, as operationalized by the categories (i) not working; (ii) return to work with adjustments; and (iii) full return to work, was determined 4 months after the onset of the sick leave. The hypothesis was tested by logistic regression analyses. High job demands were the least predictive of full return to work. However, the likelihood of employees with high job demands returning to work with adjustments was higher than the likelihood of them not working. Therefore, job demands might also work as a pressure to return to work (compare this with Smulders and Nijhuis, 1999). Furthermore, high skill discretion in combination with high job demands predicted working with adjustments in comparison with not working. Finally, high supervisor support was the most predictive of return to work without adjustments, and the least predictive of not working.