Background/Purpose: Although rheumatoid arthritis (RA) is a risk factor for osteoporosis and fracture, limited data exist in the literature concerning fracture site and frequency in patients with RA. We previously reported clinical risk factors for both incident vertebral and nonvertebral fractures in Japanese RA patients using our Institute of Rheumatology Rheumatoid Arthritis (IORRA) cohort study. Herein we expanded our previous study to evaluate fracture sites, frequencies, and causes in Japanese RA patients.

Methods: The IORRA is a prospective observational cohort study of Japanese RA patients at the Institute of Rheumatology, Tokyo Women’s Medical University (Tokyo, Japan) that was started in 2000. A total of 9,720 patients (82% female; mean age, 56 years) with RA were enrolled in the IORRA cohort study from 2000 to 2010. All participants self-reported whether they had a fracture event within the previous 6 months, the site of fracture (ankle, arm, cervical spine, clavicle, elbow, femoral neck, foot, hand, knee, leg, nose, pelvis, rib, shoulder, thoracic spine, lumbar spine, wrist, and others), and the reasons for fracture (accident, fall, spontaneous event, or sports injury) every 6 months from October 2000 to October 2010. We then analyzed the sites, frequencies, and causes of the fractures to clarify the epidemiology of fractures in Japanese RA patients.

Results: During a mean (SD) duration of 5.2 (3.3) years, 1357 patients reported a total of 2076 incident fractures. Among them, 837 (61.7%) reported a single fracture, 520 (38.3%) reported two fractures, 303 (22.3%) reported three fractures, and 217 (16.0%) reported more than three fractures. Overall, 287 (13.8%) vertebral fractures and 1789 (86.2%) nonvertebral fractures (head: n=35, 1.7%; trunk: n=504, 24.3%; upper limb: n=508, 24.5%; and lower limb: n=742, 35.7%) were reported. The most frequent fresh nonvertebral fracture was rib (n=368, 20.6%), followed by toe (n=276, 15.4%), femoral neck (n=178, 9.9%), ankle (n=132, 7.4%), wrist (n=122, 6.8%), hand (n=117, 6.5%), shoulder (n=105, 5.9%), arm (n=86, 4.8%), knee (n=84, 4.7%), elbow (n=78, 4.4%), pelvis (n=71, 4.0%), leg (n=57, 3.2%), clavicle (n=56, 3.1%), and head including nose (n=35, 2.0%). Causes of overall fractures were fall in 55.5% of patients, followed by spontaneous events in 33.2%, accident in 7.8%, and sports injury in 1.0%; the major causes of vertebral fractures were spontaneous events (63.5%) and fall (27.4%), while fall (60.0%) and spontaneous events (28.3%) were the major causes of nonvertebral fractures.

Conclusion: Fourteen percent of Japanese patients with RA reported one or more incident fractures within a mean duration of 5.2 years. Unlike non-RA elderly subjects, spontaneous events were a major cause of fractures. Differences between RA patients and non-RA subjects should be at least in some part due to the significant osteoporosis seen in RA patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/fracture-sites-frequencies-and-causes-in-9720-japanese-patients-with-rheumatoid-arthritis-a-prospective-observational-cohort-study/