Background Osteoarthritis (OA) generally is regarded clinically as asymmetrical, and monoarticular or pauciarticular, in contrast to symmetrical, polyarticular rheumatoid arthritis (RA). However, the risk of osteoarthritis in any joint is higher in patients who already have osteoarthritis in other joints, and many OA patients have bilateral disease (1). Therefore, we have compared the likelihood of self-report of pain and possible patterns of symmetry in specific joints and joint groups in patients seen in routine care with a diagnosis of OA or RA.

Objectives To analyze the number and possible symmetry of painful joints and joint groups according to a rheumatoid arthritis disease activity index (RADAI) self-report joint count of 8 joints or joint groups, fingers, wrists, elbows, shoulders, hips, knees, ankles, and toes, in patients with RA or OA seen at 2 rheumatology settings.

Methods All patients seen at 2 clinical settings, Liverpool Hospital in Liverpool, New South Wales, Australia, and Rush University Medical Center, Chicago, IL, USA, complete a multidimensional health assessment questionnaire (MDHAQ) in 5-10 minutes in the waiting area prior to seeing the rheumatologist. The MDHAQ includes a rheumatoid arthritis disease activity index (RADAI) self-report painful joint count, as well as scales for physical function, pain, patient and physician global estimates, psychological distress, and fatigue. The RADAI includes a query “Please place a tick or check (√) in the appropriate spot to indicate the amount of pain you are having today in each of the [8] joint areas listed below:” fingers, wrists, elbows, shoulders, hips, knees, ankles, and toes. The 4 response options for each of 16 queries (8 right and left joints or joint groups) are: no pain =0, mild pain =1, moderate pain =2, and severe pain =3. For analyses presented here, responses were classified as either 0=no pain or 1=1, 2, or 3 positive response for pain, collapsed to one category. Data were analyzed according to descriptive statistics for mean and median values for each joint or joint group, the total number of joint groups affected, and whether a joint group was affected by unilateral or bilateral involvement in patients with OA or RA.

Results Analyses of the 16 joint groups indicated that the median number of joint groups involved was 6 at Rush and 10 at Liverpool for OA and 6 at both sites for RA. In most comparisons, the likelihood of bilateral disease was greater than for unilateral disease in OA and RA, and more than 1.5 times greater for fingers, knees, ankles, and toes in OA and RA at both settings (Table). Similar patterns were seen on the right and left side.

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Conclusions Patients with OA report similar numbers of painful joints as patients with RA, in routine care at 2 settings. The patients also report symmetrical joint involvement more commonly than asymmetrical involvement, similarly in both OA and RA. These findings highlight the substantial impact of OA from the patient perspective and suggest possible change in the clinical approach and resource allocation for OA.

References

1. Hirsch R, et al. Association of hand and knee osteoarthritis: evidence for a polyarticular disease subset. Ann Rheum Dis. 1996;55(1):25-9.

Disclosure of Interest None declared