Background/Purpose:

Fatigue is a prominent problem in persons with rheumatoid arthritis (RA) and often has a detrimental effect on quality of life. Besides variables directly related to disease and disease impact, exercise and physical performance have been found to explain variation in fatigue. However, previous studies have used small samples and the role of aerobic capacity is unclear. The present study assessed the contribution of physical performance in the variation of fatigue in RA, beyond that of previously known factors related to disease and disease impact.

Methods:

This cross-sectional study used data from the Swedish Rheumatology Quality Registers and included 269 persons recruited for a physical activity intervention. They were all diagnosed with RA according to the ACR classification criteria, 82% women, mean age 60 ± 9 years, mean DAS28 2.8 ± 1.2, and mean HAQ 0.5 ± 0.5. The participants completed a questionnaire on fatigue, activity limitation, perceived health, pain, anxiety/depression and physical activity, and were tested for physical performance; lower limb function by Timed-stands Test, grip strength by Grippit, and aerobic capacity by Åstrand’s submaximal bicycle test. Fatigue was rated on a visual analogue scale 0-100 with severe fatigue defined as 50-100. Variation in fatigue was analyzed in two logistic regression models including A) variables related to disease and disease impact, and B) variables related to disease, disease impact and physical performance. Multiple imputation was used to account for missing data in explanatory variables. Nagelkerke’s R² was calculated to assess model fit.

Results:

Severe fatigue was reported by 95 persons (35%). Significant univariate associations (p < 0.1) between severe fatigue and disease duration, medication with biological drugs, comorbidities, activity limitation, perceived health, pain, anxiety/depression and grip strength were found and those variables were included in the adjusted models. Model fit statistics indicated that model B explained more of the variance in severe fatigue than did model A. (Nagelkerke’s R² 0.60 and 0.67 respectively, p <.0001). Perceived health, pain and anxiety/depression contributed significantly (p< 0.05) in both models and lower limb function in model B (Table 1).

Conclusion:

The results indicate that perceived disease impact variables together with lower limb function are predictors of fatigue in persons moderately affected by RA.  The role of physical performance should be explored further with multidimensional assessments of fatigue in samples with larger variation in fatigue and in potential explanatory factors.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/physical-performance-contributes-only-marginally-in-explaining-fatigue-variation-in-persons-with-ra-moderately-affected-by-their-disease/