Undifferentiated Spondyloarthropathy

　　Undifferentiated spondyloarthropathy is not uncommon in clinical practice, and the vast majority of outpatients with seronegative spondyloarthropathy can be diagnosed with this disease. The prevalence of undifferentiated spondyloarthropathy is 3 to 10 times that of patients with ankylosing spondylitis in the same population. Studies on the family of ankylosing spondylitis show that among the first-degree relatives, only 1/4 to 1/2 of the patients with spondyloarthropathy can be diagnosed with confirmed ankylosing spondylitis, while the others are within the scope of undifferentiated spondyloarthropathy. Therefore, patients with undifferentiated spondyloarthropathy are more common than those with ankylosing spondylitis, which deserves our attention. The etiology of undifferentiated spondyloarthropathy is mainly the following four types:

　　1. An early manifestation of a certain confirmed spondyloarthropathy, which will progress and differentiate into a certain confirmed spondyloarthropathy in the future.

　　2. An incomplete type of a certain clear spondyloarthropathy, or called 'abortive' or 'blunted' type, which will not develop into the typical manifestations of that spondyloarthropathy in the future.

　　3. A type that belongs to a certain overlapping syndrome and will not develop into a certain confirmed spondyloarthropathy.

　　4. A type that is currently undefined and belongs to an unknown subtype, which is to be classified in the future.

　　Due to the diverse and atypical symptoms of undifferentiated spondyloarthropathy, the misdiagnosis rate is high, often misdiagnosed as intervertebral disc herniation, rheumatoid arthritis, sciatica, lumbar muscle strain, and so on. Therefore, it is necessary to increase vigilance for the disease, pay attention to buttock pain, pain in the inner thigh, hip pain, as well as heel pain, metatarsal pain, and knee swelling and pain, and carefully check for signs of tendinitis.

　　Approximately 30% of patients with undifferentiated spondyloarthropathy will eventually develop confirmed ankylosing spondylitis after several years, with a relatively higher proportion of HLA-B27-positive patients. 5% to 10% may develop other spondyloarthropathies, about 26% have recurrent oligoarthritis, and the rest of the patients do not progress further. X-ray abnormalities appear years later, such as sacroiliac joint changes requiring 9 to 14 years, and vertebral lesions requiring 11 to 16 years. Most patients diagnosed with ankylosing spondylitis after 10 years of follow-up have good vertebral function.

　　Undifferentiated spondyloarthropathy has a hidden onset, affecting both males and females, but it is more common in males, accounting for 62% to 88%. The onset age is between 16 and 23 years. Due to milder lesions and fewer affected joints in females, their average onset age is higher than that in males. Additionally, delayed onset of undifferentiated spondyloarthropathy is widespread among middle-aged people. The main clinical manifestations include:

　　1. Inflammatory lumbar and back pain, accounting for 52% to 80%.

　　2. Peripheral arthritis predominantly affecting the lower limbs (60% to 100%), commonly seen in the knee, hip, and ankle joints. It can affect one or more joints, with the latter often being asymmetric polyarthritis (40%).

　　3. Tendinous insertional disease, such as tendinitis (56%), heel pain (20% to 28%).

　　4. Sacroiliitis (16% to 30%), spondylitis (29%). Other axial joint diseases include intervertebral arthritis, cervical spondylosis, and costovertebral arthritis, etc.

　　5. Characteristic systemic manifestations, such as conjunctivitis or iridocyclitis (33%), mucocutaneous lesions (16%). Common mucocutaneous lesions include suppurative keratoderma, balanitis, and oral ulcers, with occasional cases of necrotizing cellulitis.

　　6, Other clinical manifestations: There may also be urinary and reproductive system diseases (26%), inflammatory bowel disease (4%), heart damage (8%), and other manifestations. A small number of patients with HLA-B27 positivity who develop the disease after the age of 50 may have lower limb pitting edema. Dry mouth and dry eyes may be secondary to a non-specific inflammatory involvement of the salivary glands, leading to secondary sicca syndrome.

　　Undifferentiated spondyloarthropathy seriously affects the daily life of patients, so it should be actively prevented. However, there is currently no effective preventive method for this disease, so early detection and early treatment are of great significance for the treatment of the disease.

　　The diagnosis of this disease should be classified as a whole into spondyloarthropathy, so the first step is to determine whether it is a spondyloarthropathy, which can be diagnosed according to the European Spondyloarthropathy Research Group classification criteria or the Amor Spondyloarthropathy Diagnostic Criteria, the latter of which has high sensitivity and specificity. Then, if possible, further classify into different types of spondyloarthropathy, and those who cannot be diagnosed with a specific type of spondyloarthropathy are of course undifferentiated spondyloarthropathy.

　　As for undifferentiated spondyloarthropathy itself, there is currently no unified standard. Currently, there are mainly the following 6 diagnostic methods in clinical practice:

　　1, Rheumatoid factors and autoantibodies are mostly negative. If the rheumatoid factor is positive, the positivity rate is the same as that of the normal population of the same age.

　　2, HLA-B27 positive (80% to 84%), HLA-B27 is closely related to extrajoint symptoms, and patients with HLA-B27 positivity are prone to develop inflammation to a more severe degree.

　　3, Erythrocyte sedimentation rate can accelerate (19% to 30%).

　　4, The level of IgG can be significantly increased.

　　5, Fiberoptic colonoscopy in a few cases can find asymptomatic inflammatory bowel disease, with pathological manifestations of chronic non-specific inflammation, and direct immunofluorescence showing the presence of IgG, IgA, IgM, C3, C4, and fibrinogen.

　　X-ray, CT, and MRI examinations can show sacroiliitis (16% to 30%) and spondylitis (about 20%).

　　Undifferentiated spondyloarthropathy mainly manifests as joint pain, swelling, and other symptoms of arthritis. In daily life, it is necessary to pay attention to appropriate functional exercises, avoid overexertion and catching a cold, keep warm, and eat light foods. Pay attention to the intake of calcium-rich foods. Drink plenty of water, maintain normal weight, and can also do foot therapy for health care. As for food and health products, it is recommended to follow the following principles as much as possible:

　　Choose easily digestible foods in diet, and cooking methods should be light and refreshing. Eat less spicy, greasy, and cold foods.

　　Eat more appetizing foods such as jujube and Job's tears, especially Job's tears have the effect of removing dampness and dispelling wind. Cooking Job's tears porridge or cooking them with mung beans are both good choices.

　　Reduce fat intake as much as possible, with carbohydrates and proteins as the main source of calories. If the weight exceeds the standard, it is necessary to gradually lose weight.

　　4. If the body is hot, more foods such as mung beans and watermelons should be eaten; if cold, then sheep or beef should be eaten, but the intake should not be excessive.

　　5. If taking aspirin, it must be taken after meals because this drug can easily cause stomach damage and is prone to cause iron-deficiency anemia.

　　6. Adequate intake of vitamins A, C, D, E, or mineral foods containing calcium, iron, copper, zinc, selenium, etc., to enhance immune function and prevent tissue oxidation or anemia.

　　7. If taking steroids can easily cause increased appetite, sodium retention, and osteoporosis, it is necessary to control the intake of food to avoid rapid weight gain. High-sodium seasonings and processed foods should be reduced as much as possible, and more calcium-rich foods such as skimmed milk and traditional tofu should be consumed.

　　For some patients with undifferentiated spondyloarthropathy who have only mild symptoms and signs, special treatment may not be required, or physical therapy can be used to improve symptoms. Non-steroidal anti-inflammatory drugs can be selected for patients with obvious inflammation.

　　For patients with severe arthritis symptoms and enthesopathy, corticosteroids can be injected into the affected joint or inflammatory site. When the sacroiliac arthritis is obvious and the conventional treatment is not effective, corticosteroids can be injected into the inflamed sacroiliac joint under CT guidance, and it is reported that significant efficacy can be obtained.

　　For a few patients with acute or highly active inflammation, systemic use of corticosteroids can be considered, but the dosage and course of treatment should be strictly controlled.

　　For patients with long-term chronic diseases, who have persistent arthritis and enthesopathy, if the symptoms cannot be completely controlled with non-steroidal anti-inflammatory drugs alone, immunosuppressants can be added.

　　For patients with undifferentiated spondyloarthropathy who have inflammatory bowel disease, sulphasalazine can achieve good efficacy. The mechanism may be that sulphasalazine treats inflammatory bowel disease by restoring the normal permeability of the intestinal wall and inhibiting the entry of antigens into the damaged intestinal wall, but it has no preventive effect. In addition, it is not yet clear whether the early use of sulphasalazine can improve the course of the disease and prognosis, which requires further study. As for the general clinical treatment situation in China, physicians are often willing to use sulphasalazine to treat undifferentiated spondyloarthropathy, which may be related to the moderate price of the drug and the relatively high safety of its use.