Predictors of outcome in fatigued employees on sick leave: Results from a randomised trial

The main objective of this study was to identify predictors of fatigue caseness, work resumption and chronic fatigue syndrome (CFS)-like caseness in a sample of fatigued employees on sick leave. For 12 months, 151 fatigued employees on sick leave, 44% of whom met research criteria for CFS at baseline, were followed. Measures included fatigue, health aspects, psychological problems, burnout, causal attributions and self-efficacy. Logistic regression analysis was used to determine associations between predictor variables at baseline and outcome at follow-up. After 12 months, 43% of the patients were no longer fatigue cases, and 62% had resumed work. Recovery from fatigue caseness was predicted by stronger psychological attributions and other perception-related factors, whereas work resumption was predicted by lower age, male sex, CFS-like caseness and less cognitive difficulties. Lower physical functioning scores were predictive of (the development of) CFS-like caseness. Recovering from persistent fatigue and work resumption seem to result from different underlying processes and do not necessarily fall together. As many factors associated with outcome in fatigue reflect illness perception, the prevention of persistent fatigue and CFS may partly be achieved by the modification of perception.