@article {Gouldjrheum.200673, author = {Patrick W. Gould and Babette S. Zemel and Elena G. Taratuta and Joshua F. Baker}, title = {Circulating Fibroblast Growth Factor-21 Levels in Rheumatoid Arthritis: Associations with Disease Characteristics, Body Composition, and Physical Functioning}, elocation-id = {jrheum.200673}, year = {2020}, doi = {10.3899/jrheum.200673}, publisher = {The Journal of Rheumatology}, abstract = {Objective This study evaluated associations between Fibroblast Growth Factor (FGF)-21, an adipokine associated with metabolic stress, and adverse longitudinal changes in body composition and physical functioning in patients with rheumatoid arthritis (RA). Methods At baseline and follow-up, RA patients, aged 18-70, completed whole-body Dual Energy Absorptiometry and peripheral quantitative CT to quantify lean mass, fat mass, and muscle density. Dynamometry assessed muscle strength at the hand and knee, and physical functioning was measured with the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). FGF-21 and inflammatory cytokines were measured at baseline. Linear and logistic regression analyses assessed associations between FGF-21 levels and body composition and physical functioning over time. Results 113 RA patients were enrolled, and 84 (74\%) returned for follow-up at a median of 2.68 years. At baseline, FGF-21 was associated with age, smoking, methotrexate use, adiposity, and inflammatory cytokines: TNF-RI, YKL-40, VEGF, and resistin. The highest FGF-21 quartile was associated with worse SPPB and HAQ. Higher baseline FGF-21 levels (per 1 SD) were associated with worsening in muscle density and area z-scores [β=-0.056 (-0.12, 0.008), p=0.08; β=-0.049 (-0.10, 0.006), p=0.08] and a greater probability of a clinically meaningful worsening of HAQ [OR=2.37 (1.21, 4.64), p=0.01]. The fourth FGF-21 quartile was associated with worsening of SPPB [β=-0.57 (-1.04, -0.091), p=0.02]. Conclusion FGF-21 levels are associated with obesity and inflammatory cytokines, and with worsening in physical functioning in RA. These data support the hypothesis that FGF-21 can identify patients at risk of functional decline.}, issn = {0315-162X}, URL = {https://www.jrheum.org/content/early/2020/10/27/jrheum.200673}, eprint = {https://www.jrheum.org/content/early/2020/10/27/jrheum.200673.full.pdf}, journal = {The Journal of Rheumatology} }