Results
Focus group study
Many participants indicated that the term fatigue did not adequately describe the sensation they experienced on a daily basis. Five descriptive themes emerged: feeling exhausted or tired; feeling heaviness in the limbs or whole-body; sensing fogginess in the head; feeling weakness in the muscles; and feeling drained of energy. These descriptors were nominated consistently across the groups, and no new themes emerged in the last group.Table 1 shows the word frequency analysis of the key descriptors within each of the nominated themes.
These themes revealed distinct‘physical’ and‘mental’ fatigue domains, and participants consistently suggested a clear differentiation, for example: “I still suffer not just physical fatigue, but the biggest thing I find for me personally is the mental fatigue,”(1:2);“I find that mental fatigue also makes you physically fatigued,”(1:3);“If I let myself get really mentally fatigued, I'm that much closer to being physically fatigued, and vice versa. They definitely feed into each other but they are quite separate to me.”(5:4).
This sense of distinct mental fatigue was commonly associated with patients' reduced cognitive performance:“I've read one novel in 14 years. I just cannot get through a novel. I pick bits out of books or I read the headlines in the paper every day and that's about it, really.” (3:1);“When I'm fatigued, I feel very overwhelmed and [it's] very hard to make a decision—even simple things, it's just overwhelming…” (5:1). The functional impact of the cognitive difficulties was commonly reported to be pronounced while driving:“I'm going home, thinking, ‘This is dangerous. I am so tired. I shouldn't be driving.’ I mean I've certainly been in that situation.”(4:6).“I probably shouldn't drive as much as I do at the moment because sometimes I just find myself driving and it's like,‘whoa! I've just been driving for 15 min and I can't remember a thing about it.’”(2:1). Reduced cognitive performance was occasionally associated with the sense of being cognitively wired (e.g.“Some days it's almost like I go hyper, my brain just goes so fast. If I'm really tired and have to lie down a lot, my brain goes even faster. It's really hard to settle my brain down.”3:1) or disoriented (e.g. feeling spaced out, or out of it, or like being in a dream)