Background Few studies of which joints most affect physical function in rheumatoid arthritis (RA) patients have been conducted.
Objectives Using the National Database of Rheumatic Diseases by iR-net in Japan (NinJa), a multicenter, rheumatic disease database, the present study investigated the effects of bilateral and unilateral disease in the shoulder, elbow, wrist, hip, knee, ankle, finger, and toe joints on the modified Health Assessment Questionnaire (mHAQ) scores.
Methods The subjects were the 9,212 patients (1,766 men, 7,466 women) with complete medical records among the 10,367 patients registered in NinJa in fiscal year 2011. The presence or absence of disease in each joint (swelling and pain were considered disease) and whether the disease was bilateral or unilateral were investigated. The presence of disease in the finger or toe joints was defined as swelling or pain in at least one metacarpophalangeal joint, metatarsophalangeal joint, or proximal interphalangeal joint. The impacts of bilateral and unilateral disease of each joint on mHAQ scores were investigated using logistic regression analysis.
Results The patients were aged 63.2±12.9 years, and their duration of symptoms was 12.2±10.7 years. The majority of subjects had moderate disease activity (mean baseline 28-joint Disease Activity Score, 3.3±1.3). The median mHAQ score was 0.25. The 2 most frequently affected joints were the finger joints (42.2%) and wrist (36.6%), followed by the knee (21.2%), ankle (20.9%), toe joints (18.7%), elbow (17.8%), and shoulder (11.5%). In contrast, the frequency of hip joint involvement was small (2.0%). Significant correlations were observed between the mHAQ scores and bilateral and unilateral disease of all joints apart from bilateral disease of the hip and bilateral and unilateral disease of the toes. The odds ratios for each joint (95% confidence interval) bilaterally and unilaterally, respectively, were as follows: shoulder, 4.0 (2.9 to 5.6) and 1.8 (1.5 to 2.1); elbow, 2.6 (2.1 to 3.4) and 1.8 (1.5 to 2.1); wrist, 1.9 (1.7 to 2.2) and 1.5 (1.3 to 1.7); hip, 1.7 (0.7 to 4.7) and 3.0 (2.0 to 4.7); knee, 2.6 (2.2 to 3.2) and 1.9 (1.7 to 2.2); ankle, 2.3 (1.9 to 3.0) and 2.0 (1.8 to 2.4); finger, 1.4 (1.2 to 1.5) and 1.2 (1.0 to 1.3); and toe, 1.0 (0.8 to 1.3) and 1.1 (0.9 to 1.3) (Fig. 1).
Conclusions While mHAQ scores were significantly affected by disease in almost all joints, a greater effect was exerted by the major joints, in increasing order of ankle, knee, elbow and shoulder. Bilateral disease tended to have a greater effect than unilateral disease in these major joints and the wrist.
Disclosure of Interest : None declared
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