What does a positive rheumatoid factor indicate?

The positivity rate of rheumatoid factor (RF) in patients with rheumatoid arthritis (RA) is 70% to 80%, especially in those with extensive lesions, severe conditions, long disease course, active phase, and extra articular lesions, with high positivity rate, high titer, and long-term existence. Therefore, RF is commonly used as one of the diagnostic criteria for rheumatoid arthritis internationally. In fact, in clinical practice, besides rheumatoid arthritis, RF is also seen in normal individuals, especially the elderly, with a positive rate of up to 5% to 10%. For patients with other diseases, such as people with various infectious diseases, such as hepatitis B, tuberculosis, subacute bacterial endocarditis and chronic bronchitis, and people with connective tissue diseases, such as lupus erythematosus, Sjogren's syndrome, dermatomyositis, vasculitis, scleroderma, pre vaccination and some malignant diseases, the RF positive rate can reach 10% to 70%. Therefore, in the diagnosis of RA, it is generally believed that RF has only reference value and no specific diagnostic value. RF positivity does not necessarily indicate rheumatoid arthritis. To make a clear diagnosis, other relevant tests need to be performed and experienced doctors should be consulted for comprehensive analysis.

Reminder: RF is commonly used as one of the diagnostic criteria for rheumatoid arthritis internationally. In fact, in clinical practice, besides rheumatoid arthritis, RF is also seen in normal individuals, especially the elderly, with a positive rate of up to 5% to 10%.