Table 3.

Reported fatigue associations in the included studies

Study ID	Associations
Alencar 2022 a [7]	Non-functional ambulatory patients had a higher level of fatigue (P = 0.026). There was a positive association between fatigue and the inability to walk (P = 0.034)
Alencar 2022 b [37]	There was a positive association between fatigue and pain intensity (P = 0.001). Fatigue was negatively associated with ALSFRS-R (P = 0.003), muscle strength (P = 0.004), and quality of life (P = 0.001)
An 2022 a [38]	There was a positive association between fatigue and the presence of pain (P = 0.032)
An 2022 b [39]	The ALS severity, sleepiness, and daytime dysfunction were associated with a higher risk of fatigue (P = 0.002, 0.045, and 0.001, respectively)
Lococo 2012 [9]	Fatigue was negatively associated with ALSFRS-R, forced vital capacity (P = 0.001), and sleep quality (P = 0.01). Fatigue was positively associated with sleepiness (P = 0.007) and depression (P = 0.003). Patients with fatigue were significantly more disabled (P < 0.001) and more frequently reported difficulties staying asleep (P = 0.009) and nocturnal complaints (P = 0.002)
McElhiney 2009 [40]	Fatigue was significantly and negatively associated with ALSFRS-R and positively with depression and ALS severity (P < 0.001)
Panitz 2015 [41]	Patients with fatigue had lower ALSFRS-R values (P < 0.01)
Sandstedt 2016 [43]	Fatigue was associated with worsening health-related quality of life (P = 0.01)
Vangroenestijn 2017 [44]	Fatigue was positively associated with participation restrictions (P ≤ 0.01)
Vogt 2020 [36]	Fatigue was significantly associated with worse health-related quality of life

ALSFRS-R, Amyotrophic Lateral Sclerosis Functional Rating Scale- Revised