Background Rheumatoid arthritis (RA) patients suffer from disabling fatigue, and both The American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) have identified fatigue as an outcome of great importance to patients. Patients describe their fatigue to be physical and/or mental fatigue, which makes them unable to complete their daily tasks. Since the aetiology of fatigue is unknown, Treatment of fatigue is a great challenge.
Objectives Trying to find some of the causes behind fatigue, our aim was to assess which of the variables: disease activity, disease duration, and pain, could be associated to fatigue.
Methods A systematic literature search in the bibliographic databases Medline and EMBASE followed by selection of studies according to set criteria, data extraction, and statistical analyses of the relationships in RA between fatigue and the covariates: disease duration, erythrocyte sedimentation rate (ESR), C-reactive Protein (CRP), DAS28, swollen/tender joints, and pain. Linear regression analyses of fatigue regressed on each of the six covariates, and a multiple regression analysis where fatigue was regressed on the six covariates through a forward selection procedure was carried out with construction of correlation measures between fatigue and the covariates.
Results 121 studies were included in the analyses, including >100.000 RA patients. A high level of fatigue was seen even in well-treated patients (according to DAS28), demonstrating fatigue as a major problem in RA. Fatigue was found positively correlated to Pain, CRP, DAS28, and ESR, but not to the Swollen/Tender joint-ratio, or Disease duration. When the covariates were considered simultaneously with pain, the additional information contained in the other covariates were negligible, pain was the overall domineering factor in experience of fatigue.
Conclusions Fatigue has a substantial influence on the lives of RA patients, independent of disease duration. Pain is the domineering factor in the experience and degree of fatigue. Disease activity is positively correlated to fatigue, but does not contribute substantially when pain is considered. Optimal pain relief is therefore an important part of the treatment if one wishes to improve fatigue in RA.
The protocol for this study was registered in Prospero with registration number: CRD42013004178.
Acknowledgements This study was supported by the OAK Foundation
Disclosure of Interest None declared