Analysis of rheumatoid factor according to various hepatitis B virus infectious statuses

Objective: Rheumatoid factor (RF) can be seen in hepatitis B virus (HBV) infection. We investigated RF positive rates according to various HBV infectious statuses and vaccination, and the relationship between RF titers and serum HBV DNA levels. Methods: We examined 13,670 individuals who visited the Severance Hospital in Seoul, Korea, for a routine health check-up, and obtained serum samples from all individuals. Results: RF was positive in 3.5% of all subjects, and HBsAg was positive in 4.3%. HBsAg was positive in 21.7% of all RF positive subjects. RF was positive in 17.5% of the HBsAg positive group, while it was positive in 2.9% of the HBsAg negative group (p<0.001). The RF positive rate was increased in positive HBsAg, female sex, and older age. The RF positive rate was lower in those who had anti-HBs after HBV vaccination than in HBsAg positive subjects (2.7% vs. 17.5%, p<0.001). Among the RF positive patients, the RF titer in HBsAg positive patients were higher than that in HBsAg negative patients (159.7±217.1IU/mL vs. 83.0±179.2 IU/mL, p=0.001). The load of HBV DNA may be closely correlated with RF titer in patients with chronic hepatitis B (r=0.508, p=0.005). Conclusion: Persistent HBV infection is an important cause for the positive RF in HBV endemic areas. Hepatitis B viral load is associated with RF titer. HBV vaccination may reduce the risk of RF formation.