Frailty refers to a stage that precedes the various complications that cause mental and physical deterioration due to aging, which require nursing care [1]. The number of frail patients is increasing in aging societies such as Japan, and the growing burden of medical expenses and long-term care insurance premiums for younger generations is a major social problem [2]. Given the reversible nature of frailty, early intervention is important for returning to good health.

Rheumatoid arthritis (RA) is an autoimmune disease that results in joint destruction from intra-articular synovitis. RA patients are more likely to become frail than their healthy counterparts due to joint deformity and muscle weakness around the joints. In recent years, advances in the development of DMARDs have reduced the number of patients with systemic arthritis. However, local control of arthritis continues to be difficult [3]. In addition, RA has the highest prevalence among patients with connective tissue diseases worldwide (0.5–1.0 % in Japan), and thus, the demand for appropriate treatment is high [4]. For these reasons, a better understanding of frailty management in RA patients is essential.

Comorbidities, such as pulmonary, renal, and liver dysfunction, cause problems in various situations and increase the risk of frailty in patients as compared with healthy people [5]. Moreover, poor control of disease activity in RA patients correlates with frailty [6]. To make matters worse, RA patients with comorbidities often have difficulty controlling disease activity since physicians avoid administering methotrexate (MTX), the anchor drug of RA therapy, due to concerns about side effects [7]. Therefore, RA patients with comorbidities are more prone to frailty than patients without comorbidities.

Against these backdrops, the present study aimed to investigate factors associated with frailty in RA patients, focusing on comorbidities using updated data from an observational study in 2022.