Autoantibodies as prognostic markers in rheumatoid arthritis.

Background and purpose: Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by progressively destructive polyarthritis. Key autoimmune features include the presence of autoantibodies. The purpose of this review is to discuss the diagnostic and prognostic properties of rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA), based on current use in Sweden. Furthermore, we discuss their relation to disease outcomes and their importance for management of patients with RA. Principal findings: Based on current cut-offs, ACPA has a higher specificity for RA than RF, and testing for ACPA alone is recommended when investigating patients with clinically suspect RA. The diagnostic utility of RF may improve with adjusted reference range/upper limit of normal.RF and ACPA both predict rapid radiographic progression, severe extra-articular manifestations and mortality, whereas other outcomes, such as osteoporosis, pain and disability are not as clearly related to seropositivity. RF/ACPA positive patients respond better to some targeted therapies, in particular rituximab, compared to seronegative RA patients. Recent studies indicate that treatment of ACPA-positive arthralgia with abatacept may delay and perhaps sometimes even prevent development of arthritis. Available evidence does not support an added value of repeated RF or ACPA testing. Conclusions: Testing for ACPA in patients with arthralgia or suspected early RA, and for ACPA and RF at RA diagnosis, provides useful diagnostic and prognostic information, which has implications for follow-up and treatment. Repeated testing for ACPA and RF is not recommended. Potential future developments include treatment of ACPA-positive individuals for prevention of arthritis.