Severe fatigue in people with rheumatoid arthritis (RA) is associated with self-rated health, pain, and anxiety/depression rather than with physical capacity, a recent study found. Participants were recruited for a physical activity intervention and the database included questionnaires on fatigue, activity limitation, perceived health, pain, and anxiety/depression and from physical capacity tests (lower limb function, grip strength, and aerobic capacity). Researchers used logistic regression to estimate the association between severe fatigue (≥ 50, visual analogue scale 0–100) and (A) independent variables related to disease and disease impact and (B) model A plus physical capacity tests. They found:
- Out of the 269 participants (mean age 60 years, mean disease activity score [DAS28] 2.8), severe fatigue was reported by 35%.
- The 3 variables that were statistically significantly associated with severe fatigue in both models were perceived health, pain, and anxiety/depression.
- Anxiety/depression demonstrated the largest effect size with odds ratios of 2.43 in model A and 2.58 in model B.
- The likelihood ratio test indicated that model B was a better fit to the data than model A with Χ2 (df 3) = 2.65.
Demmelmaier I, Pettersson S, Nordgren B, Dufour AB, Opava CH. Associations between fatigue and physical capacity in people moderately affected by rheumatoid arthritis. [Published online ahead of print August 29, 2018]. Rheumatol Int. doi:10.1007/s00296-018-4140-z.
Although somewhat difficult to define and measure, fatigue is a real concern to patients with RA. This study evaluated factors that may be associated with fatigue in 269 patients with RA who had volunteered to participate in a 2-year support program for health-enhancing physical activity. The patients had relatively mild RA, with 33% in remission, according to DAS-28 score, and with a mean HAQ-DI of only 0.5%. Severe fatigue was significantly associated with perceived disease impact, and with higher HAQ score of subjective assessment of health, pain, and anxiety/depression. There was only a marginal significance for association with grip strength. Researchers conclude that physical capacity is only marginally associated with severe fatigue, but the validity of this conclusion may be compromised by the low disease activity of the majority of the participants. This study is useful in that it provides additional information about multiple factors that may contribute to fatigue in patients with RA. —Harold E. Paulus, M.D.; Emeritus Professor; University of California, Los Angeles; Division of Rheumatology.