Altered energy expenditure may contribute to the nutritional complications of RA, metabolic syndrome (MS) and rheumatoid cachexia (RC). The main aim of this study was to evaluate whether the altered resting energy expenditure (REE) and physical activity (PA)-related energy expenditure (EE) are related to the duration of RA and inflammatory activity and nutritional complications in RA.
Among patients with well-characterized RA (duration, activity: DAS28 ESR), we measured REE by indirect calorimetry, and PA-EE by actimetry (SenseWear Armband). MS was defined according to the International Diabetes Federation criteria and RC from DXA body composition analysis. The relations between the characteristics and nutritional complications, and EE were analysed by linear regression.
Fifty-seven patients were included [73% women, age 57 (10) years] with a wide range of disease duration: 3.8 (3.0) years, and DAS28 ESR: 3.9 (1.4). The mean REE was 1486 (256) kcal/day, associated with the DAS28 ESR (β = +0.21, P = 0.02 after adjusting for gender and fat free mass). The prevalence of MS and RC was, respectively, 24 and 18%, and they were unrelated to each other. The patients with MS and/or RC had double the longstanding RA score (P < 0.05), twice the homeostasis model assessment of insulin resistance values (P = 0.052) and halved levels of PA (P < 0.05 for metabolic equivalent tasks (METs) and number of steps/day). Two modifiable factors were associated with the presence of MS and/or RC: a low level of PA as METs [exp(B) = 0.03, P = 0.009] and the use of glucocorticoids [exp(B) = 4.08, P = 0.046].
Low levels of PA and treatment by glucocorticoids are associated with the nutritional complications of RA, suggesting the potential for therapeutic interventions.