American Board of Internal Medicine (ABIM) Certification Practice Exam

Which combination of autoantibodies is most specific for diagnosing rheumatoid arthritis?

1. Anti-Ro/SSA and Anti-La/SSB

2. Anti-cyclic citrullinated peptide antibodies and Rheumatoid factor

3. Anti-dsDNA and Anti-Smith

4. Anti-phospholipid and Anti-nuclear antibodies

The correct answer is: Anti-cyclic citrullinated peptide antibodies and Rheumatoid factor

The most specific combination of autoantibodies for diagnosing rheumatoid arthritis is indeed anti-cyclic citrullinated peptide (anti-CCP) antibodies and rheumatoid factor (RF). Anti-CCP antibodies are particularly significant in the context of rheumatoid arthritis as they demonstrate a higher specificity compared to other autoantibodies. These antibodies are directed against citrullinated peptides, which are often present in inflamed joints in rheumatoid arthritis patients. The presence of anti-CCP antibodies can be detected early in the disease process, making it a valuable biomarker for diagnosing rheumatoid arthritis. Rheumatoid factor, while less specific on its own and found in various other conditions, is also commonly associated with rheumatoid arthritis. When combined with anti-CCP testing, the duo yields a more reliable diagnostic profile, aiding health care providers in confirming a diagnosis of rheumatoid arthritis versus other autoimmune disorders or inflammatory conditions. The other combinations listed do not offer the same specificity for rheumatoid arthritis. For example, anti-Ro/SSA and anti-La/SSB are mainly associated with Sjögren's syndrome and systemic lupus erythematosus. Anti-dsDNA and anti-Smith antibodies are highly specific for lupus rather than rheumatoid arthritis. Lastly, anti-phosph