Fatigue after stroke: its frequency, natural history and associations with mood, physical activity and physical fitness
Duncan, Fiona Helen
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Background: Fatigue is common and distressing after stroke. Many stroke survivors say it is their worst or one of their worst symptoms. The frequency of clinically significant fatigue, whether fatigue is likely to be more or less problematic over time, and its aetiology are unknown. There are currently no known treatments. One hypothesis is that fatigue after stroke is triggered by physical deconditioning which sets up a self-perpetuating cycle of fatigue, avoidance of physical activity, further deconditioning and more fatigue. Another theory is that low mood may contribute to fatigue. Aims: This thesis therefore aims to investigate the frequency and natural history of fatigue after stroke and to explore its associations with mood, physical activity and/or fitness. Method: These aims were addressed by carrying out: 1) a systematic review of all longitudinal observational studies which have assessed fatigue on at least two separate time points and reported its frequency, 2) a systematic review of all observational studies which have measured both fatigue poststroke and one or more measures of physical activity and/or fitness at the same time point and 3) a longitudinal cohort study which assessed clinically significant fatigue, mood and physical activity and fitness at one, six and 12 months after stroke. Results: Frequency of fatigue ranged from 30% to 92% at first time point and frequency of fatigue decreased over time in seven of the ten studies identified in the systematic review of longitudinal studies. The second systematic review found that only two of the eight studies identified found a significant direct relationship between fatigue and physical activity and/or fitness poststroke. In the longtidudinal cohort study, clinically significant fatigue was identified in 32.6% of 132 participants at one month and was still present in a fifth of 91 participants at 12 months, two-thirds of participants who had clinically significant fatigue at one month did not have it by six months and that most (60.4%) individuals either reported fatigue at all three time points or that they did not have fatigue at any time point. There were significant associations between daily step count and fatigue at each time point (p=<0.0001, 0.011, 0.006). Physical activity (p=0.002, 0.006) and anxiety (p=<0.0001, 0.001) at one month were independent significant predictors of fatigue severity at six and 12 months after stroke. Age, gender, fatigue before stroke, step count and anxiety at one month accounted for 22% and 27% of the variance in fatigue severity at six and 12 months respectively. No significant associations were found between fatigue and measures of physical fitness. Discussion and conclusion: The findings suggest that although fatigue is common and persistent after stroke, it is more likely to become less problematic over time. They also suggest that the de-conditioning hypothesis of the aetiology of fatigue may be too simplistic and that other factors are involved in the development and perpetuation of fatigue after stroke. Implications are that patients should be assessed for fatigue early after stroke and that the development of an intervention which increases activity and/or reduces anxiety may be beneficial.