Prevalence of rheumatoid factor positivity in normal Egyptian population in comparison with patients suffering from osteoarthritis and rheumatoid arthritis

ABSTRACT

Rheumatoid factor was assessed in sera of 111 normal subjects, 50 patients with osteoarthritis [OS], 20 patients with connective tissue disease other than rheumatoid arthritis [other CTD] and 54 patients with rheumatoid arthritis [RA]. Latex agglutination test [Humatex RF] was used. Sera were considered positive when agglutination occurred in dilution 1 2 which is equivalent to 24 IU ml [WHO]. Eight out of 111 normal subjects were positive for RF, 5 out of 50 OA patients showed seropositivity. Five out of 20 patients with other CTD were found to be seropositive. RA patients gave 59% positivity [32 out of 54]. In conclusion, a high false positive RF in normal Egyptians and OA patients and a rather low seropositivity in RF patients were observed and raising the cut-off level for RF positivity to meet the criteria of ACR [5% positive RF in normal population] on using this test in Egypt is recommended