AB0795 DYNAMIC CHANGES IN QUANTITATIVE INDICES OF BODY COMPOSITION BY DUAL-ENERGY X-RAY ABSORPTIOMETRY IN PATIENTS WITH EARLY RHEUMATOID ARTHRITIS ON DIFFERENT THERAPEUTIC REGIMENS
Authors: Y. Gorbunova, T. Popkova, T. Panafidina, N. Demin, E. Nasonov, A. Lila
Journal: Annals of the Rheumatic Diseases (2021)

Background: A redistribution of body fat (abdominal obesity) is quite common in RA patients. Such parameters as body mass index (BMI) and waist circumference do not distinguish or quantify fat and lean (muscle) mass. For that purpose, dual-energy X-ray absorptiometry (DXA) is usually used. Objectives: to compare quantitative body composition in patients with early RA at baseline and after 24 weeks of therapy with different regimens. Methods: The study included 37pts (31 women /6 men) with early RA (ACR/EULAR criteria, 2010), 57 [46.5, 62,0] years old, naïve to treatment with glucocorticoids and disease-modifying anti-rheumatics (DMARDs). Pts were seropositive for IgM RF (76%) and anti-CCP (92%), with highly active RA (DAS28 5,5 [5,1; 6,0]; SDAI 32,4 [22,4; 42], CDAI 29,0 [19,7; 39,5]) scores, and median disease duration of 6.0 [5,5;15.5] months. Methotrexate (MTX) 10 [10-15] mg/week subcutaneously was initiated in all included patients as first line therapy for 12 weeks. By this time point therapy was reviewed in 19 patients (51%) due to MTX inefficacy and adalimumab (ADA) at 40 mg once every 2 weeks was added on top of MTX. DXA scan (HOLOGIC, USA) was used to measure body composition at baseline and after 6mths of treatment with the protocol assessing total body, body fat and lean muscle mass. Results: Based on therapeutic regimens at week 24 all study subjects were divided into 2 groups: Group I (n=18) receiving MTX monotherapy, Group II (n=19) – the combination of MTX and ADA (Table 1). Group I patients had lower body weight, lean and fat mass vs patients from Group II (62 kg vs. 73.7 kg; 40.6 kg vs. 49.7 kg; 21.0 kg vs. 25.8 kg, respectively (p&lt;0.05 in all cases) at baseline. 24 weeks of combination therapy eventuated in body weight gain (73.7 kg vs. 75.8 kg), accumulation of fat (25.8 kg vs. 28.1 kg) and unchanged lean tissue mass. In contrast, patients on MTX monotherapy managed to increase their lean mass (40.6 kg vs. 41.6 kg) without gaining in total fat mass. Table 1. Indices I group ( n =18), monotherapy МТ II group ( n =19), combination therapy (MTX, ADA) baseline 24 weeks Δ,% baseline 24 weeks Δ,% Body fat mass, kg 21,0 [17,2;26,2] ** 23,4 [17,5;29,7] +11 25,8 [18,4;35,0] 28,1 [21,4;37,9] * +9 Lean mass, kg 40,6 [37,3;44,7] ** 41,6 [38,2;46,4] ***/ * +2,5 49,7 [39,0;56,1] 49,9 [41,0;57,6] 0,4 Total mass, kg 62,0 [57,7;77,6] ** 64,1 [59,5;81,6] *** +3,4 73,7 [64,5;97,9] 75,8 [66,8;102,1] * +2,8 *p&lt;0,05 reliability of differences in parameters before treatment and after 6mth (Wilcoxon); **p&lt;0.05 differences in baseline values in groups I and II (Mann-Whitney test);***p&lt;0.05 difference in the indices between the groups by the 6mth of therapy; Δ,% difference in indices between the groups by the 6mth of therapy. Conclusion: In general, RA patients on treatment tend to gain weight by week 24. Patients who failed on MTX monotherapy by week 24 and were switched to combination therapy had higher fat mass at baseline. Mediations used for RA treatment produce multidirectional effects on quantitative parameters of body composition: MTX monotherapy triggers some increase of lean mass, while combination of MTX and bDMARD results in weight gain and increase of total and fat mass. These data need to be confirmed in large-scale studies with longer follow-up period. Disclosure of Interests: None declared