Osteoporosis is associated with a lower prevalence of body mass index-defined obesity in rheumatoid arthritis

Objective. The objective of this initial phase of the study is to retrospectively screen rheumatoid arthritis (RA) phenotype characteristics associated with osteoporosis. Methods. The study included all RA patients who randomly came to the university rheumatology department between January and July 2018. Demographic data, anthropometric data, RA-specific variables, osteoporosis data and comorbidities were collected retrospectively and cross-sectionally from the first (and most frequently the only) observation sheet of each patient within the study timeframe. Correlations and comparison were analyzed using appropriate non-parametric tests, all of the reported being significant (p<0.05). Results. The sample included 149 RA patients (60.8 years mean age; 81.2% women), 40 (26.8%) of which had osteoporosis and 31 (20.8%) were obese. Compared to RA patients without osteoporosis, RA patients with oste- oporosis were significantly older (56.0 respectively 71.0 years) and had: lower body mass index (BMI; 23.8 kg/m 2 respectively 29.6 kg/m 2 ), longer disease duration (11.0 respectively 17.0 years), higher prevalence of rural dwell- ing (prevalence ratio – PR=2.46), smoking (PR=3.71), inflammation (PR=1.35), anti-citrullinated protein antibody positivity (PR=1.51), glucocorticoids (PR=1.85) and carotid artery disease (PR=3.01), but a lower prevalence of obesity (PR=3.43). Lumbar bone mineral density was significantly correlated with BMI (rho=0.294) and with rheumatoid factor titers (rho=0.311), controlling for age, gender and disease duration. Conclusions. BMI-defined obesity seems to be associated with a lower prevalence of osteoporosis among RA patients, while disease severity (treatment with glucocorticoids, inflammation and ACPA positivity) is associated with a higher prevalence of osteoporosis. Gain of adipose tissue and loss of bone tissue seem to be antagonistic and parallel body composition alterations in RA.