Background Patients with rheumatoid arthritis (RA) complain about fatigue. However, little is still known about its causes and consequences. A fully developed theoretical model explaining the experience of fatigue in RA is lacking.
Objectives Goal of this study was to systematically review studies in RA that examined factors related to fatigue and differences in fatigue between RA patients and other patient groups, to gain more insight in possible causes and consequences of fatigue in RA.
Methods Four databases were searched for relevant studies; MEDLINE, Web of Science, SCOPUS and PsychInfo. All studies with RA samples about the relation between fatigue and other variables, that defined dependent and independent variables and used multivariate statistical methods, were included in the review. One hundred twenty nine studies were preliminary included. After reviewing the full-texts, we identified twenty-four studies on possible causes of fatigue, fifteen studies on possible consequences of fatigue and ten studies comparing levels of fatigue between groups.
Results Studies found possible causes of fatigue in illness-related aspects (e.g. pain), physical functioning (e.g. disability), cognitive/emotional functioning (e.g. depression) and social aspects (e.g. interpersonal events). Additionally, female gender was related to more fatigue. Inflammatory activity (e.g. ESR, DAS28) showed an unclear relationship with fatigue in RA. Possible consequences for fatigue were found among illness-related aspects (e.g. morning stiffness), physical functioning (e.g. physical quality of life), cognitive/emotional aspects (e.g. psychological distress) and social aspects (e.g. work ability). Patients reported higher severity of fatigue than healthy subjects and fibromyalgia patients reported worse levels of fatigue than other patient groups. Most evidence for a relation between fatigue and other variables was found regarding pain, physical functioning and depression. Many cross-sectional and also longitudinal studies reported that these variables were associated with fatigue.
Conclusions This study gave an overview about variables that are related to fatigue in RA and information about fatigue levels in RA compared to other patient groups. However, most of the included studies were cross-sectional and not all longitudinal studies controlled for baseline fatigue so that hardly conclusions about causal relationships could be drawn. Prospective longitudinal studies with adequate designs and analyses are needed to find out more about the multicausal pathways of fatigue in RA.
Disclosure of Interest None Declared