The Positive Rate of Serum Rheumatoid Factor in Health Screening Subjects and Related Factors

ABSTRACT

BACKGROUND: This study was done to estimate the prevalence of Rheumatoid Factor (RF) positive rate in adult Korean population and to investigate the association between rheumatoid factor positive rate and related factors. METHODS: The database from 4,678 subjects, who visited a general health screening center of an university hospital during 1 year period were surveyed. RF was tested using a commercial latex test kit, HBsAg by RIA of 3rd generation, anti-HCV by EIA of 3rd generation and serum AST, ALT by enzyme kinetic method. Syphilis was checked using RPR test and TPHA. Lung diseases (tuberculosis, IPF) were screened using chest X-ray. Flukes was checked by sedimentation method and cestodes was by direct method in stool tests. Smokers were based on history on health screening. RESULTS: 1) The positive rate of RF was 4.4%, HBsAg was 5.9%, anti-HCV was 1.5% and ALT>35 IU/L was 18.4%. The number of syphilis subjects was 19, lung diseases was 119, parasitic diseases was 43, and smokers was 1,299. 2) RF positive rate of males was 4.0%, females was 5.3%. Therefore, the positivity of females was higher than males and RF positivite rate was increased in the higher age groups. 3) RF positive rate in HBsAg (+) subjects was 18.1% and HBsAg (-) was 3.6% and in anti-HCV (+) subjects was 10.3% and anti-HCV (-) was 4.3%. 4) RF positive rate of subjection both positive reactions of RPR test and TPHA, namely, syphilis tests was 21.1%. 5) RF positive rate of parasitic diseases was 4.7%, lung diseases was 2.5% and smokers was 4.2%. 6) RF positive rate was highly associated with HBsAg, syphilis, anti-HCV, female sex, age in order of sequence. CONCLUSION: The positive rate of RF in healthy Korean adults can be estimated to be 4.5% and shows high association with hepatitis B and C virus infection in addition to syphilis, age and sex.