Background In Rheumatoid Arthritis (RA) alterations in the amount and distribution of fat and lean mass result in abnormal body composition phenotypes probably as a consequence of persistent inflammatory state. Lower lean mass and the sarcopenia phenotype have been associated with disability previously.
Objectives The aim of this study was to determine whether a reduced Lean Body Mass (LBM) is associated with a more severe joint damage in RA
Methods A cross-sectional study, conducted in consecutive established RA woman patients seen in our Rheumatology Department between 2012 and 2014. RA was defined using the ACR 1987 criteria. Patients with overlap syndrome (except Sjogren), prosthetic or metallic elements, infections, trauma/ recent surgery, cancer, hospitalized, pregnant or weight>120 kg were excluded. An interview, chart review, physical examination and laboratory tests were performed. All subjects providing written informed consent. LBM was determined by dual X-ray absorptiometry (DXA) and was expressed as the LBM Index (kg/ m2). Joint damage (JD) was measure according to Sharp VD Heijde method (erosion, joint space narrowing and total score). The association between LBM and JD was evaluated using Pearson's correlation. Subsequently, a linear regression model was performed to evaluate the persistence of these association adjusted by age, age at diagnosis, disease duration, Socioeconomic status according to Graffar's scale, tobacco habit, ACPA title, disease activity using the DAS28 ESR, glucocorticoids use and functional capacity (MHAQ questionnaire)
Results One hundred and seventy-four women patients were included. The average (SD) age was 57.7 (12.7) years. Disease duration was 14.4 (10.6) years; all patients were mestizo. ACPA title was 768.8 (1357.3) uM/L, DAS28 was 4.8 (1.3), the Sharp VD Heijde total score was 168 (93.6) and the Body Mass Index (BMI) was: 28.19 (4.81) kg/m2. The LBM was 6.03 kg/m2 (0.9) and the percentage of fat Body Mass (FBM) was 38.46 (4.56)
In the univariate analysis, according to Pearson correlation Index, a lower LBM was associated with a more total (-0.27, p=0.00); erosion (-0.27, p=0.001) and space narrowing (-0.25, p=0.001) Sharp VDH scores. In the multivariate model adjusted by age, age at diagnosis, disease duration, Graffar's scale, tobacco, ACPA, DAS28, glucocorticoids use and MHAQ, these correlation persisted (erosion score: B: -0.010, p=0.002; space narrowing score: B: -0.012; p=0.002 and total score: B: -0.006 p=0.001)
Conclusions A lower Lean Body Mass was associated with a more severe joint damage independently of other risk factors. Strategies aimed at preserving lean muscle mass could have a favorable impact on the course of disease.
Disclosure of Interest None declared