Rheumatoid arthritis is a systemic autoimmune disease characterized by chronic joint inflammation that eventually results in bone destruction and severe disability. Rheumatoid arthritis should be considered in any patient with clinical synovitis in at least one joint. The diagnosis of rheumatoid arthritis depends on the number of joints involved, the amount of inflammation, and the presence of auto-antibodies detected in the sera of the patients. Rheumatoid factor (RF) is detectable only in ∼70% of patients with rheumatoid arthritis, and may be present in other diseases. With its high specificity (89–96%) and reasonable sensitivity (65–88%), anti?cyclic citrullinated peptide antibodies (anti?CCP) plays an important role in the diagnosis of rheumatoid arthritis. Anti?CCP is directed to proteins that contain the unusual amino acid citrulline, which is derived from the post?translational modification of arginine by peptidylarginine deiminases. Anti?CCP and rheumatoid factor are useful in the preclinical and early diagnosis of rheumatoid arthritis. Not only the presence but also the level of auto-antibodies is of predictive relevance.

Spondyloarthritis (SpA) are a group of inflammatory arthritis which consist of ankylosing spondylitis (AS), reactive arthritis (Reiter's syndrome), arthritis/ spondylitis associated with psoriasis (PsA), enteropathic spondylitis or spondylitis associated with inflammatory bowel disease (including Crohn's disease and ulcerative colitis), and undifferentiated spondyloarthropathy. The term axial SpA has been used to describe the entire spectrum of SpA that has predominant axial involvement. Patients with axial SpA are often diagnosed late in the course of the disease. The Assessment of SpondyloArthritis international Society (ASAS) has developed new classification criteria for axial SpA. The ASAS criteria are to be applied in patients with back pain of > 3 months and age at onset of back pain <45 years. ASAS classification criteria for axial SpA have imaging and clinical arms. SpA clinical features included inflammatory back pain, arthritis, enthesitis (heel), uveitis, dactylitis, psoriasis, Crohn’s disease or ulcerative colitis, good response to NSAIDs, family history of SpA, HLA-B27, and elevated C-reactive protein. Inflammatory back pain is the key clinical symptoms of patients with axial SpA. HLA-B27 is the key laboratory marker of axial SpA. The imaging arm includes either sacroiliitis on conventional radiography or sacroiliitis on MRI, which enable detection of pre-radiographic changes in early SpA. It has been proven effective in identifying patients with axial SpA that patients are tested for the presence of inflammatory back pain and HLA-B27, followed by referral to a rheumatologist.