Low aerobic capacity and physical activity not associated with fatigue in patients with rheumatoid arthritis: a cross-sectional study.

OBJECTIVE To explore whether low aerobic capacity and physical activity are associated with fatigue, when controlling for age, gender, pain and depressive symptoms in persons with rheumatoid arthritis. METHODS In 60 individuals fatigue (Multidimensional Assessment of Fatigue scale; MAF), disease activity (Disease Activity Score-28; DAS 28), pain, physical and psychological status (Arthritis Impact Measurement Scales 2; AIMS 2), depression (Hospital Anxiety and Depression Scale; HADS), aerobic capacity and physical activity (Short Questionnaire to Assess Health-enhancing physical activity; SQUASH) were measured. Regression was performed to study the variance of fatigue explained by aerobic capacity and physical activity. RESULTS Mean (standard deviation (SD)) age of participants was 51.8 (SD 10.4) years and 73.3% were women. Duration of disease was 10.2 (SD 0-41) years and mean disease activity score was 3.4 (SD 1.4). Mean Global Fatigue Index was 20.3 (SD 10.5). Physical function was 1.6 (SD 1.1) and psychological status 3.1 (SD 0-8) on the AIMS2. Pain score was 4.1 (SD 2.0) and median depression score was 3.2 (range 0-15). Total amount of physical activity was 176.9 (10.6-1,492.3) METhours/week and VO2max was 27.8 (SD 3.8) ml/kg/min. Backward multiple regression showed a statistically significant relationship with depressive symptoms only (t = 5.4, p < 0.001), which explained 33% of variance of fatigue in patients with RA. CONCLUSION Depression, but not aerobic capacity or physical activity, contributed to fatigue. However, no relationship was found between aerobic capacity and fatigue.