Rheumatoid arthritis (RA) is a disease characterized by chronic progressive and symmetrical arthritis, which can be accompanied by extra-articular systemic damage. It is one of the common rheumatic diseases, mostly seen in women aged 30 to 50. The prevalence in our population is 0.32% to 0.38%, which is lower than the 1% to 2% of whites in Europe and America. The early pathological changes are mainly synovial inflammation of the joints, with clinical manifestations such as joint swelling, pain, numbness, morning stiffness, and unfavorable activities; later inflammation continues to erode, and when cartilage and bone are involved, it can lead to destruction of joint structures, deformity and dysfunction, resulting in different degrees of disability. The cause of this disease is not yet clear, its pathogenesis is related to autoimmune abnormalities, so far there is no curative drug, but early diagnosis, early treatment, early patients can mostly obtain good control, avoid deformation and disability, so as to maintain a good quality of life; intermediate and late patients can also be actively treated to stop the progress of the disease, to protect the workforce, improve the quality of life and maintain health status.
I. What is rheumatoid factor? What is its clinical significance?
Rheumatoid factor (RF) is an autoantibody used to detect certain antigens in the patient’s serum, according to its type is divided into IgA-RF, IgM-RF, IgE-RF, IgG-RF, etc. At present, the main type of routine detection is IgM -Most patients with high clinical suspicion of rheumatoid arthritis have a positive RF test, but some patients have a negative test, which is the different types listed above, and can be detected by other special methods.
Rheumatoid factor (RF) has a positive rate of about 50% to 70% in rheumatoid arthritis, and is one of the important serological criteria for the diagnosis of rheumatoid arthritis. Persistent high titers of RF often indicate active rheumatoid arthritis, a high incidence of bone erosion, and a poor prognosis. High titers of RF are also seen in other rheumatic diseases, such as.
(1) autoimmune diseases systemic lupus erythematosus, dry syndrome, mixed connective tissue disease, systemic sclerosis, polymyositis/dermatomyositis, IgA nephropathy, etc.
(2) Infectious diseases Hepatitis, tuberculosis, bacterial endocarditis, schistosomiasis.
(3) Non-infectious diseases Diffuse interstitial lung fibrosis, nodular disease, macroglobulinemia, etc.
Clinically, arthritis is classified into two major categories, RF positive and RF negative, based on RF characterization. A positive RF alone cannot diagnose rheumatoid arthritis, and a negative RF cannot exclude the diagnosis of rheumatoid arthritis. In addition, the normal population, especially the elderly, will also be detected in 5% of positive RF.
Second, the onset of rheumatoid arthritis and what factors are related?
The cause of rheumatoid arthritis is not fully understood, but it is believed that its development is related to a variety of factors.
（The rate of specific gene positivity in rheumatoid arthritis patients is significantly higher than that of normal people.
(2) Infectious factors Patients with rheumatoid arthritis have significantly higher serum anti-EB virus antibodies and anti-Chlamydia antibodies, suggesting that the disease is related to infectious factors. In addition, mycobacteria, cytomegalovirus and retrovirus may be related to rheumatoid arthritis.
(3) Endocrine factors The prevalence of rheumatoid arthritis is low in women who take birth control pills and are pregnant, and is significantly higher in those who develop rheumatoid arthritis after giving birth. Men with rheumatoid arthritis have decreased testosterone levels.
(4) Other factors such as cold, wet and cold, fatigue, trauma, smoking and mental stimulation.
Third, rheumatoid arthritis typical joint performance
(1) Morning stiffness lasting 1 hour is diagnostic for rheumatoid arthritis (RA).
(2) Pain and swelling of multiple joints, small joints and symmetrical joints, especially pain and swelling of proximal interphalangeal joints, metacarpophalangeal joints and wrist joints. The phenomenon of “trigger finger” or “hinge-unlocking” may occur, as well as cystic sensation around the small joints due to synovial thickening, swelling and pressure pain in the soft tissues on the extensor side of the wrist joint.
(3) Joint deformities include pike swelling, ulnar deviation deformity, proximal interphalangeal joint palmar subluxation, crest and valley deformity, ulnar subluxation, buttonhole flower and swan neck deformity, claw-shaped hand, telescope hand, crossed toe deformity, heel valgus deformity, etc.
(4) Osteoporosis. Pathological osteoporosis is common in the joints eroded by the lesions.
Fourth, the common clinical tests related to rheumatoid arthritis
(1) rheumatoid factor: (see: a. What is rheumatoid factor? What is its clinical significance?)
(2) Blood sedimentation (ESR): the clinical significance of increased blood sedimentation
Physiological increase Blood sedimentation changes with age and gender, generally higher in women than in men, and also increases in some women during menstruation and from the third trimester to one month after delivery; it may also increase in young children.
Most rheumatic diseases may increase during the inflammatory phase, such as systemic lupus erythematosus, rheumatic fever, rheumatoid arthritis, ankylosing spondylitis, dry syndrome, dermatomyositis, vasculitis, nodular disease, etc. When the disease improves and remits, it will drop significantly or return to normal. However, increased sedimentation is not unique to rheumatoid arthritis and cannot be used as a specific diagnostic indicator. Increased sedimentation can occur in other acute inflammatory diseases, such as active tuberculosis, anemia, malignant tumors, heavy metal poisoning, etc.
(3) C-reactive protein (CRP).
CRP is a glycoprotein in the serum of certain diseases, which is an acute reactive phase substance, and its elevation can be seen in various acute septic inflammation, tissue necrosis, malignancy and rheumatic diseases and other diseases. It is important for the diagnosis of inflammatory activity in rheumatoid arthritis.
(4) Anti-cyclic guanosine polypeptide antibody (CCP)
Anti-cycloguanine polypeptide antibody (CCP) is a newly discovered antibody with high diagnostic significance for rheumatoid arthritis. It has a specificity of 96% and a sensitivity of 76%. Its specificity is significantly higher than that of rheumatoid factor (RF) and can be used for the early diagnosis of rheumatoid arthritis.
(5) Anti-keratin antibody (AKA)
Anti-keratin antibodies (AKA) are related to the activity and severity of rheumatoid arthritis and often appear early in the disease or even when clinical symptoms are not obvious. Follow-up of people with positive antibodies reveals a higher incidence of classic rheumatoid arthritis. Therefore, anti-keratin antibodies are important for the diagnosis and prognosis of rheumatoid arthritis, with a sensitivity of 33% and specificity of 87% – 95% for the diagnosis of rheumatoid arthritis.
(6) Anti-RA33/RA36
RA33 antibody can be found in early rheumatoid arthritis, which is good for early diagnosis. RA36 antibody is only found in rheumatoid arthritis, which has high specificity. Therefore, the combination of the two tests is meaningful for the differential diagnosis of rheumatoid arthritis.
V. What is rheumatoid nodules?
Rheumatoid nodules are a special clinical manifestation of rheumatoid arthritis, which often appear during the rheumatic activity and can disappear on their own. Rheumatoid nodules are found in 20% – 25% of patients with rheumatoid arthritis, mostly under the skin where pressure or friction is frequent, such as the elbow, knee, behind the ear, ankle and other parts. The nodules range in size from a few millimeters to a few centimeters, are tough and rubbery and do not move easily, and are generally painless to touch or pressure.
Rheumatoid nodules are an important extra-articular manifestation of rheumatoid arthritis. The presence of nodules often indicates disease activity, and with disease control or remission, rheumatoid nodules will shrink or disappear. It can be used as one of the observation indicators of the improvement of the disease.
The rheumatoid arthritis onset and course of performance
The onset of rheumatoid arthritis is divided into acute, subacute and insidious onset
1, the acute onset of multiple joint swelling, pain, morning stiffness, unfavorable activities, or accompanied by low fever, fatigue, loss of appetite, wasting, etc., often appear within a few days symmetrical. If the disease is not treated and controlled in a timely manner, joint destruction will occur quickly, affecting the function of the limbs and causing a decline in the quality of life and work of patients.
2.Sub-acute onset type The onset of the disease is slightly slow, and the clinical symptoms are similar to those of the acute onset type within a few weeks, and the development of the disease is slower than that of the acute onset type.
3, insidious onset type The initial onset is mostly pain and swelling in one or several joints, or numbness and morning stiffness in hands and feet. Most patients will experience a longer period of clinical remission, followed by recurrent episodes and progressive exacerbation; the continued development of the disease process will also cause joint damage.
VII. Special types of rheumatoid arthritis
The special types of rheumatoid arthritis are roughly the following.
1. age-related rheumatoid arthritis.
2, seronegative (also known as rheumatoid factor negative) rheumatoid arthritis.
3, rheumatoid arthritis secondary to dry syndrome, and
4, adult Still’s disease.
5.Rheumatoid disease
6, seronegative symmetric synovitis with sunken edema syndrome, and
7.Felty syndrome, etc. (To be continued at the end)