Background/Purpose: Patients with rheumatoid arthritis (RA) are at high risk of developing fractures. Previously, utilizing data from our Institute of Rheumatology Rheumatoid Arthritis (IORRA) cohort study, we reported clinical risk factors for clinical vertebral and any nonvertebral fractures in women [1] and men [2] and hip fractures [3] in Japanese patients with RA . However, we did not evaluate the risk factors for distal radius fractures alone, because in our previous studies, the number of distal radius fracture patients was small. In this study, we evaluated the association between potential risk factors and the occurrence of distal radius fractures and compared the risk factors for clinical vertebral, any nonvertebral, and hip fractures in Japanese patients with RA [1-3].

Methods: IORRA is a prospective observational cohort study of Japanese patients with RA at the Institute of Rheumatology, Tokyo Women’s Medical University that was established in 2000. A total of 9,987 patients (82.0% female; mean age, 55.7 years) with RA were enrolled in a prospective, observational study from 2000 to 2011. Self-reported distal radius fractures were verified using patient medical records. Cox proportional hazards models were used to analyze independent contributions of various risk factors to distal radius fracture occurrence.

Results: During a mean follow-up period of 5.7 years, 139 patients reported 153 distal radius fractures. Among these patients, 85 distal radius fractures in 85 patients (6 men, 79 women) were verified by medical records. The multivariate Cox regression analyses estimated that the hazard ratios of sustaining a distal radius fracture increased by 15.27 for female gender [95% confidence interval (CI), 1.96-119.02], 1.60 for every 10 years of increased age (95% CI, 1.15-2.22), 1.11 for body mass index (BMI) (kg/m², 95% CI, 1.01-1.22), and 1.09 for daily prednisolone dose (mg, 95% CI, 1.01-1.18). Unlike risk factors for clinical vertebral, any nonvertebral, and hip fractures evaluated using data from this same cohort [1-3], no significant association was observed between the occurrence of distal radius fractures and Japanese health assessment questionnaire (J-HAQ) disability score (Table). A high BMI was a risk factor for distal radius fractures, whereas a low BMI was a risk factor for hip fractures [3] (Table).

Conclusion: Female gender, advanced age, high BMI, and high daily prednisolone dose appear to be associated with the occurrence of distal radius fractures in Japanese patients with RA. Risk factors appear to be different between distal radius, clinical vertebral, any nonvertebral, and hip fractures in Japanese patients with RA.

Table Risk factors for fractures in Japanese patients with RA

Risk factors Fractures	Clinical vertebral	Any nonvertebral	Hip	Distal radius
Advanced age	Yes [1]	Yes [1, 2]	Yes [3]	Yes
Female gender	ND	ND	NS [3]	Yes
J-HAQ disability score	Yes [1,2]	Yes [1]	Yes [3]	NS
Body mass index (BMI)	NS [1,2]	NS [1,2]	Low BMI [3]	High BMI
Daily prednisolone dose	Yes [2]	NS [2]	NS [3]	Yes
History of orthopedic  surgery for RA	Yes (any) [1]	Yes (TKR) [2]	Yes (TKR) [3]	ND

ND, not determined; NS, not significant; TKR, total knee replacement

References: 1) Furuya T, et al. J Rheumatol 34: 303-310, 2007; 2) Furuya T, et al. J Bone Miner Metab 26: 499-505, 2008; 3) Furuya T et al. Osteoporos Int 24: 1257-1265, 2013

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-factors-associated-with-fracture-occurrence-appear-to-differ-between-distal-radius-clinical-vertebral-and-hip-fractures-in-japanese-patients-with-rheumatoid-arthritis-a-prospective-observ/