Rheumatoid factors are passe, and frequently false positive. the "ccp" antibody is more definitive! what does that mean?

See details: It means that the diagnosis of RA is much more likely if the ccp is positive. The rheumatoid factor can be falsely positive much more often than the ccp.

Both are useful: Most rheumatologists find both tests useful; rf is not "passe." rf is not specific for ra, meaning most patients with RA have an abnormal rf, but many people with abnormal rf do not have RA (false positive). E.G., hepatitis c infection can cause an abnormal rf without ra. In contrast, antibodies to ccp are more specific, so almost everyone with abnormal ccp will have or develop ra.