Clinical observations of osteoporosis in Japanese patients with rheumatoid arthritis

Osteoporosis is one of the major adverse outcomes in patients with rheumatoid arthritis (RA). Recently, we and others have been reported many clinical observations related to osteoporosis in Japanese RA patients. In this article, I reviewed these findings. Japanese patients with RA have a 2-fold risk of fractures compared with those without RA. Among the fractures in Japanese RA patients, three-quarters of the fractures were non-vertebral fractures. The incidence of non-vertebral fractures did not change, despite an improvement in RA disease activity. Older age, female gender, history of fractures, history of total knee replacements, disease activity scores in 28 joints (DAS28), health assessment questionnaire disability index (HAQ-DI), low bone mineral density, glucocorticoid dose, and vitamin D deficiency were significantly associated with fractures. Older age, high body mass index (BMI), HAQ-DI, and polypharmacy were significantly associated with falls. BMI (both overweight and underweight), DAS28, and HAQ-DI were significantly associated with frailty. Half and three-quarters of Japanese men and women with RA had vitamin D deficiency, respectively. The incidence of osteonecrosis of the jaw may be higher in Japanese RA patients than in those without RA. Undertreatment of osteoporosis appears to exist in Japanese patients with RA.