The effect of self-assessed fatigue and subjective cognitive impairment on work capacity: The case of multiple sclerosis

Objectives: The impact of physical disability in multiple sclerosis on employment is well documented but the effect of neurological symptoms has been less well studied. We investigated the independent effect of self-reported fatigue and cognitive difficulties on work. Methods: In a large European cost of illness survey, self-reported fatigue, subjective cognitive impairment (SCI), and productivity at work were assessed with visual analogue scales (VAS 0-10). The analysis controlled for country, age, age at diagnosis, gender, education, and physical disability. Results: A total of 13,796 patients were of working age and 6,598 were working. Physical disability had a powerful impact on the probability of working, as did education. The probability of working was reduced by 8.7% and 4.4% for each point increase on the VAS for SCI and fatigue, respectively (p < 0.0001). Regular work hours decreased linearly with increasing severity of fatigue and cognitive problems, while sick leave during the 3 months preceding the assessment increased. Finally, the severity of both symptoms was associated with the level at which productivity at work was affected (p < 0.0001). Conclusion: Our results confirm the independent contribution of self-reported fatigue and SCI on work capacity and highlight the importance of assessment in clinical practice.