Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic, aggressive arthritis. Rheumatoid arthritis is characterized by synovitis and the resulting destruction of joint cartilage and bone, which ultimately leads to joint deformity. Without regular treatment, approximately 75% of patients become disabled within 3 years. Rheumatoid arthritis is distributed worldwide, with a prevalence of 0.18% to 1.07% in different populations, with some racial differences in its development, with Indians being more likely than Caucasians and Caucasians more likely than yellow Asians. The total number of patients in China is more than 5 million. Rheumatoid arthritis can develop in all ages, with a peak age of about 30-50 years, and generally more women than men.
Joint manifestations
The symptoms of rheumatoid arthritis involve joints with symmetrical, persistent joint swelling and pain, often accompanied by morning stiffness. The most commonly affected joints are the proximal interphalangeal joints, metacarpophalangeal joints, wrists, elbows, and toe joints. In the middle and late stages, patients may develop “swan neck” (Figure 1) and “button flower” (Figure 2) deformities of the fingers, joint ankylosis and metacarpophalangeal joint subluxation, showing ulnar deviation of the metacarpophalangeal joint.
Extra-articular manifestations
1. Rheumatoid nodules: Mostly found in the joint prominence and frequently pressed areas, no obvious pressure pain, not easy to move. Rheumatoid nodules can also occur in internal organs, such as pericardial surface, endocardium, central nervous system, lung tissue and sclera.
2. Vasculitis: It can affect all types of blood vessels, with involvement of medium and small arteries being more common. It may manifest as gangrene of the fingertips, skin ulcers, peripheral neuropathy, sclerositis, etc.
3. Heart: pericarditis, non-specific heart valve inflammation, myocarditis.
4. Pleura and lung: pleurisy, interstitial fibrosis, pulmonary rheumatoid nodules, pulmonary arterial hypertension.
5. Kidney: membranous and thylakoid proliferative glomerulonephritis, interstitial nephritis, focal glomerulosclerosis, proliferative nephritis, IgA nephropathy, and amyloidosis.
6. Nervous system: sensory peripheral neuropathy, mixed peripheral neuropathy, multiple mononeuritis and inlay peripheral neuropathy.
7. Hematopoietic system: patients with rheumatoid arthritis may develop orthocytic orthochromic anemia and elevated platelets during active disease.
Ancillary tests
1. Routine examination.
(1) blood routine: about 30% of rheumatoid arthritis patients combined with anemia, mostly orthocytic orthochromic anemia. Platelets are elevated during active disease. In a few cases, there is a decrease in white blood cells, such as Felty’s syndrome.
(2) Acute phase reactants: Most patients with rheumatoid arthritis have increased sedimentation and elevated C-reactive protein during the active phase, which may return to normal when the disease is in remission.
2. Autoantibodies.
(1) rheumatoid factor (RF): 75%-85% of patients have positive serum rheumatoid factor and correlate with disease and extra-articular manifestations.
(2) anti-citrullinated protein antibody (ACPA): anti-citrullinated protein antibody is a general term for a class of autoantibodies against citrullinated epitopes, which has high sensitivity and specificity for the diagnosis of rheumatoid arthritis and is closely related to the disease and prognosis of rheumatoid arthritis.
3. Synovial fluid examination: The joint fluid of patients with rheumatoid arthritis is generally inflammatory in character, and the total number of leukocytes can reach (10~10000) ×10/L. The cell classification is dominated by neutrophils.
4. Imaging examinations.
(1) X-ray examination: early X-ray shows swelling of soft tissues around the joint and osteoporosis near the joint; as the disease progresses, joint surface destruction, joint space narrowing, joint fusion or dislocation may occur.
(2) Magnetic resonance imaging (MRI): MRI is better than X-ray in showing joint lesions and has been increasingly used in the diagnosis of rheumatoid arthritis in recent years. MRI can show synovial thickening, bone marrow edema and mild joint surface erosion at the beginning of the inflammatory response of the joint, which is beneficial for the early diagnosis of rheumatoid arthritis.
(3) Ultrasound: High-frequency ultrasound can clearly show the joint cavity, synovial membrane, bursa, joint cavity fluid, articular cartilage thickness and morphology, etc. Color Doppler flow imaging (CDFI) and color Doppler energy map (CDE) can visually detect the distribution of blood flow in the joint tissue and reflect the synovial membrane hyperplasia with high sensitivity. Ultrasonography can also dynamically determine the amount of joint fluid and the distance from the body surface, which can be used to guide joint puncture and treatment.
Diagnosis.
2010 American Rheumatism Association/European League Against Rheumatism Classification Criteria: Those with at least one joint with definite clinical synovitis (swelling) that cannot be better explained by other diseases may be classified as rheumatoid arthritis by applying the following scoring system with a score of 6 or more
A: Involved joints: Any swollen or tender joints found on examination that can be confirmed by imaging evidence of synovitis.
-1 large joint (0 points): Large joints refer to shoulder, elbow, hip, knee and ankle joints
-2 to 10 large joints (1 point)
-1~3 small joints (with or without large joints) (2 points): small joints refer to the metacarpophalangeal joint, proximal interphalangeal joint, 2~5 metatarsophalangeal joints, interphalangeal joint of the thumb and wrist joint
-4 to 10 small joints (with or without large joints) (3 points)
-more than 10 joints (at least one small joint) (5 points): in this article, at least one affected joint must be a small joint; other joints may include any combination of large or additional small joints, such as other joints not specifically listed elsewhere (temporomandibular joint, acromioclavicular joint, sternoclavicular joint)
B: Serology (at least 1 result required).
-negative for rheumatoid factor and anti-citrullinated protein antibodies (0 points)
-Rheumatoid factor and anti-citrullinated protein antibodies, at least one of which is low titer positive. (2 points)
-Rheumatoid factor and anti-citrullinated protein antibodies, at least one high titer positive (3 points)
C: Acute phase reactants (at least 1 result required).
-Normal CRP and ESR (0 points)
- Abnormal CRP or ESR (1 point)
D: Duration of symptoms.
-<6 weeks (0 points)
-≥6 weeks (1 point)
Note: Within A~D, take the highest score that the patient meets the condition. For example, if the patient has 5 small joints and 4 large joints involved, the score is 3.
(3) Classification criteria for early rheumatoid arthritis introduced in China in 2012
1, morning stiffness ≥ 30 minutes
2.Polyarthritis (arthritis in at least 3 or more parts of 14 joint areas)
3, hand arthritis (arthritis in at least 1 part of the wrist or metacarpophalangeal or proximal interphalangeal joints)
4.Positive anti-CCP antibody
5.Positive rheumatoid factor
Those who meet 3 or more of the above 5 items can be classified as rheumatoid arthritis. Sensitivity 84.4%, specificity 87.4%.