In advanced rheumatoid patients, there is no difficulty in diagnosis because of the presence of polyarticular lesions and typical deformities. However, in the early stages of the disease and in a few cases with joint involvement, there are often difficulties in diagnosis. At present, there are different criteria for the diagnosis of rheumatoid arthritis in different countries. 1958, the American College of Rheumatology proposed modified diagnostic criteria, which are used in many countries. They are described as follows.
(1) Morning stiffness.
(2) Pain or pressure on movement of at least one joint.
(3) Swelling of at least one joint (soft tissue hypertrophy or effusion rather than osteophytes, as seen by the physician).
(4) Swelling of at least one other joint (seen by the physician; the time interval between the two joints involved should not exceed 3 months).
(5) Symmetrical joint swelling (visible to the physician), invading the same joint on both sides of the body (full symmetry is not required if the proximal interphalangeal, metacarpophalangeal, or toe joints are invaded); involvement of the distal interphalangeal joint does not meet this criterion.
(6) A subcutaneous nodule (visible to the physician) at the bone elevation or on the extensor side near the joint.
(7) Standard radiographic findings (in addition to osteophytes, there must be osteoporosis present near the involved joint).
(8) Positive rheumatoid factor.
(9) Poor coagulation of mucin in the synovial fluid.
(10) Three or more of the following synovial pathologic changes are present: marked villous hyperplasia; superficial synovial cell hyperplasia and fenestrations; marked chronic inflammatory cell (primarily lymphocytes and plasma cells) infiltration and tendency to form lymph nodes; dense fibrin deposition in the superficial or interstitial layers; and focal necrosis.
(11) Histologic changes in the subcutaneous nodes should show foci of cellular necrosis in the central area surrounding fenestrated proliferating macrophages and a chronic inflammatory cell infiltrate in the outermost layer.
Typical rheumatoid arthritis: the diagnostic criteria require 7 of the above items. In items (1)-(5), joint symptoms must persist for at least 6 weeks.
Definite rheumatoid arthritis: 5 of the above items are required for the diagnosis of rheumatoid arthritis. In items (1)-(5), joint symptoms must last for at least 6 weeks.
Probable rheumatoid arthritis: The diagnosis requires 3 of the above items and at least 1 of (1)-(5). The joint symptoms must last for at least 6 weeks.
Suspected rheumatoid arthritis: Its diagnosis requires 2 of the following items, and the duration of joint symptoms should be at least 3 weeks.
① Morning stiffness.
② pressure pain and pain on movement (seen by the physician), intermittent or lasting for at least 3 weeks.
③History of joint swelling or as seen.
④Subcutaneous nodules (as seen by the physician).
⑤ Increased blood sedimentation and positive C-reactive protein.
⑥Iriditis (unless in childhood rheumatoid arthritis, otherwise of suspicious value).