Rheumatoid Factor Positivity in Various Conditions

Autoimmune and Connective Tissue Diseases

The European League Against Rheumatism recommends considering rheumatoid factor (RF) positivity in the diagnosis of Sjögren's syndrome, as RF positivity occurs in checkpoint inhibitor-induced sicca syndrome, though at lower rates (9% RF positive) compared to classical Sjögren's syndrome 1

The American Thoracic Society notes that RF is more prevalent in patients with bronchiectasis compared to healthy controls, particularly in those with underlying rheumatoid arthritis, with rheumatoid arthritis accounting for 2-5% of bronchiectasis cases 2, 3
The British Thoracic Society guidelines state that anti-CCP antibodies are strongly positive in only 12% of RF-positive bronchiectasis patients, with only half subsequently developing rheumatoid arthritis 3

The European League Against Rheumatism recommends considering RF levels in the diagnosis of checkpoint inhibitor-related vasculitis, as all vessel-sized vasculitis (large, medium, and small vessels) can occur with cancer immunotherapy, though RF is rarely positive in these cases, with levels ranging from 18-246 IU/mL in checkpoint inhibitor-induced arthritis 1, 4
The American College of Rheumatology notes that cryoglobulin and RF were rarely positive in vasculitis associated with checkpoint inhibitors 4

The American College of Rheumatology recommends interpreting RF results alongside clinical findings, anti-CCP status, and other laboratory tests, as negative RF does not exclude rheumatoid arthritis, and RF alone cannot predict rheumatological disease 5, 6