Association between sarcopenia defined as low lean mass by dual-energy X-ray absorptiometry and comorbidities of rheumatoid arthritis: Results of a nationwide cross-sectional health examination

To examine the association between sarcopenia and comorbidities among patients with rheumatoid arthritis (RA). We selected RA patients and age- and sex-matched non-RA controls at a 1:5 ratio from 2008-2011 Korea National Health and Nutrition Examination Survey database. Sarcopenia was defined by appendicular skeletal muscle mass. After investigating associations between sarcopenia and individual comorbidities among RA patients, we performed a stratified analysis comparing three subgroups (RA/sarcopenia, RA/non-sarcopenia, non-RA/sarcopenia) versus a non-RA/non-sarcopenia subgroup to evaluate interactive as well as independent effects of sarcopenia and RA on comorbidities. Health-related behaviors (exercise, smoking, drinking, and diet) were also examined. The weighted logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs) adjusting for age, sex, and income. We included 400 RA patients and 2,000 non-RA controls (mean age 57.4 years, 79.6% female). Sarcopenia was observed in 20.5% of RA and 19.3% of non-RA group. Among RA patients, sarcopenia was associated with obesity (OR 2.61, 95% CI 1.42-4.83), dyslipidemia (3.09, 1.37-6.99), diabetes (2.07, 0.99-4.33), chronic obstructive pulmonary disease (18.77, 2.40-146.55), and hepatitis B ever-infection (8.69, 1.15-65.58). Among three stratified subgroups, only a RA/sarcopenia subgroup was associated with such comorbidities, cardiovascular diseases, and depression compared to a non-RA/non-sarcopenia subgroup. Health-related behaviors were comparable between patients with and without sarcopenia. In this nation-wide cross-sectional study, a wide spectrum of comorbidities were preferentially found among RA patients with sarcopenia than without, suggesting that sarcopenia is significantly associated with RA-related comorbidities. Particular attention should be paid to comorbidities of sarcopenic RA patients.