ASSESSMENT OF MUSCLE MASS RELATIVE TO FAT MASS AND ITS ASSOCIATION WITH DISEASE ACTIVITY STATUS AND PHYSICAL FUNCTIONING IN RHEUMATOID ARTHRITIS

Background: Rheumatoid arthritis (RA) is an autoimmune, chronic, progressive, inflammatory disease characterized by symmetrical, destructive polyarthritis and is accompanied by systemic manifestations. RA patients show low appendicular lean mass index (ALMI) and higher fat mass index. Impaired physical function is associated greater with fat mass and the adiposity is an important confounder that may mask true relationships between physical functioning and ALMI (1). Objectives: To assess muscle mass relative to fat mass and verify associations this parameter with disease activity status, functional capacity and biologics treatments. Methods: 90 RA patients, aged between 40 and 70 years, were recruited and followed for 12 months. Body composition was assessed by total body dual-energy x-ray absorptiometry for measurement of appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI, kg/m2). Age-, sex-, and race-specific Z- Scores and T-Scores were determined by comparison to published reference ranges. ALMI values were adjusted for FMI (ALMIZ/FMIZ) using a published method. Disease activity was assessed by Disease Activity Score-28 with erythrocyte sedimentation rate (DAS28). RA patients were divided in non-remission (DAS28<2.6) and in remission (DAS28>2.6). Physical functioning was assessed by Health Assessment Questionnaire (HAQ). Pharmacological treatment used by patients were assessed in patient medical records and the RA were divided in RA patients treated with biologic disease modifying antirheumatic drugs (bDMARDs) and non-treated with bDMARDs. Frequency analysis, Pearson Correlations and GEE analyses were used and statistical significance was considered as p<0.05. Results: Of the 90 patients analyzed, most were women (86.7%,78/91), with mean age of 56.5±7.3 and median disease duration time of 8.5 (3-18) years. At baseline, the mean±SD DAS28 score was 3.7±1.4 and thirty percent of the RA patients (27/90) were treated with bDMARDs. After 12 months, the use of bDMARD did not change (p>0.05), however, mean DAS28 increased over time (mean and SD of 4.0±1.3; p<0.05). Eleven RA patients (12.2%) showed low ALMI/FMI for age (Z-score ≤-1) at baseline, and 13 (16.0%) after 12 months. After 12 months, ALMIZ/FMIZ was inversely associated with HAQ (r=-0.3; p<0.05). At, baseline, women in remission had higher ALMIZ, lower FMIZ and higher ALMIZ/FMIZ, while men had lower ALMIZ, lower FMIZ and higher ALMIZ/FMIZ. In men, remission was associated with decreases in FMIZ (p<0.05). The use of bDMARDs was not related with alterations in ALMIZ, FMIz and ALMIZ/FMIZ (p>0.05). Conclusion: Low skeletal muscle mass relative to adiposity was common in RA patients. This condition was associated with low physical functioning and its changes over time are associated with disease activity status. The observations that skeletal muscle mass relative to adiposity was affected by remission state stresses and that associated negatively with poor physical functioning demonstrate the importance of adequate control of disease activity in RA established. In addition, from our results, further studies are necessary to elucidate the direct impact of bDMARDs on body composition in RA patients. REFERENCES: [1] Weber D, Long J, Leonard MB, Zemel B, Baker JF. PLoS One. 2016; 10;11(10):e0164385 Acknowledgement: We thank the Coordination for the Improvement of Higher Level Personnel (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—CAPES) institution, the Foundation for Research Support of the Rio Grande do Sul State (Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul—FAPERGS), the Research and Events Incentive Fund (Fundo de Incentivo à Pesquisa e Eventos—FIPE) of HCPA and Technological Development (Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq). Disclosure of Interests: Rafaela Cavalheiro do Espírito Santo: None declared, Jordana Miranda de Souza Silva: None declared, Joshua Baker: None declared, Vanessa Hax: None declared, Claiton Brenol Shareholder of: Has participated in clinical and/or experimental studies related to this work and sponsored by AbbVie, BMS, Janssen, Pfizer and Roche; has received personal or institutional support from AbbVie, BMS, Janssen, Pfizer and Roche; has delivered speeches at events related to this work and sponsored by AbbVie, Janssen, Pfizer and Roche, Grant/research support from: Has participated in clinical and/or experimental studies related to this work and sponsored by AbbVie, BMS, Janssen, Pfizer and Roche; has received personal or institutional support from AbbVie, BMS, Janssen, Pfizer and Roche; has delivered speeches at events related to this work and sponsored by AbbVie, Janssen, Pfizer and Roche, Consultant for: Has participated in clinical and/or experimental studies related to this work and sponsored by AbbVie, BMS, Janssen, Pfizer and Roche; has received personal or institutional support from AbbVie, BMS, Janssen, Pfizer and Roche; has delivered speeches at events related to this work and sponsored by AbbVie, Janssen, Pfizer and Roche, Paid instructor for: Has participated in clinical and/or experimental studies related to this work and sponsored by AbbVie, BMS, Janssen, Pfizer and Roche; has received personal or institutional support from AbbVie, BMS, Janssen, Pfizer and Roche; has delivered speeches at events related to this work and sponsored by AbbVie, Janssen, Pfizer and Roche, Speakers bureau: Has delivered speeches at events sponsored by AbbVie, Janssen, Pfizer and Roche, Lidiane Filippin: None declared, Priscila Lora: None declared, Ricardo Xavier Consultant for: Abbvie, Pfizer, Novartis, Janssen, Lilly, Roche DOI: 10.1136/annrheumdis-2019-eular.4446Citation: Ann Rheum Dis, volume 78, supplement 2, year 2019, page A217Session: HPR Abstract session II (Scientific Abstracts)