Model of understanding fatigue after stroke.

F atigue is ubiquitous but it is more common and more severe in patients with acute and chronic conditions, including stroke. The reported proportion of people with fatigue after stroke ranges from 23% to 75%. 1 The variation in proportion between studies reflects the heterogeneity in the studied populations , time since stroke, and assessment methods for fatigue. Fatigue is common immediately after stroke, and it tends to persist in most but not all patients. It contributes to lower quality of life and a higher risk of death. 2,3 How to manage and prevent fatigue is ranked by stroke survivors and health professionals among the top 10 research priorities relating to life after stroke. 4 However, there is no effective treatment, which is partly because of our lack of knowledge of its mechanisms. Fatigue after stroke may share some common underlying mechanisms with other conditions. For example, Zedlitz and colleagues found that the psychosocial profiles of stroke patients with fatigue were similar to those reported in patients with cancer, multiple sclerosis, and chronic fatigue syndrome. 5 Several fatigue models have been developed for patients with other conditions; a myriad of biological, 6,7 psychosocial, 8,9 and behavioral factors, 9 as well as other symptoms, such as pain and sleep problems, 10 are involved. In this review, we explored whether these factors contribute to fatigue after stroke. We systematically reviewed studies of post-stroke fatigue (PSF) and discussed the definition of PSF, its natural history, and its associations. By drawing on literature of fatigue in other conditions alongside evidence from stroke studies, we propose a conceptual model of PSF. This model is potentially useful in understanding the mechanisms of PSF and informing the development of its treatment. In stroke studies, PSF is usually defined by cutoff scores on fatigue scales, which are often devised in nonstroke populations. Among over 50 fatigue scales used in research studies, only 7 have been tested for their psychometric properties in a stroke population, and all showed feasibility and validity in assessing PSF. Furthermore, dichotomizing patients by a single cutoff score does not fully characterize fatigue that matters to stroke survivors. To address this weakness, a case definition for PSF was developed, of which the criterion was self-reported significant fatigue that interfered with daily activities. 13 This definition is valid and reliable in identifying clinically significant fatigue in stroke survivors. 13 A study found that a third of …