Protective Role of Rheumatic Diseases Against Hepatitis B Virus Infection and Human Leukocyte Antigen B27 Highlighted

BACKGROUND: By determining the hepatitis B virus (HBV) surface antigen (HBsAg) positive rate postexposure and HBV-specific antigen/antibody (Ag/Ab) level in patients with rheumatic diseases, we aimed at exploring the rheumatic link to HBV control. METHODS: Patients who underwent HBV screening in the Ruijin Hospital from 2020 to 2021 were enrolled for the exposure rate estimation. Among antibody to HBV core antigen (HBcAb)-positive patients, we adopted propensity score matching (PSM) to study the impact of rheumatism on HBsAg seroprevalence after exposure. A second PSM evaluated the Ag/Ab differences. We also had HBsAg prevalence in human leukocyte antigen B2 (HLA-B27) tested patients studied. RESULTS: With 33,989 screened patients, exposure rates remained comparable between rheumatic and non-rheumatic patients: 48.94 vs. 49.86%. PSM first yielded 2,618 balanced pairs. We observed significantly fewer patients with rheumatic diseases in HBsAg positive cases than negative ones (p < 0.001). In the second round, PSM matched 279 pairs, HBsAg (p < 0.001) and HBeAg (p < 0.05) positivity rates were significantly lower in the rheumatic patients, whereas HBsAb positivity rate (p < 0.001) and level (p < 0.01) were significantly higher. Though the value of HBcAb was overall significantly lower (p < 0.001) within the realm of rheumatic diseases, patients with ankylosing spondylitis (AS) demonstrated a significantly higher value than other rheumatic diseases. We saw significantly fewer HBV infections in HLA-B27 positive subjects than in the negative ones (p < 0.001). CONCLUSION: In this propensity score-matched study, rheumatic patients had an advantage in HBV control. In rheumatic patients, HBcAb levels, together with the beneficial role of HLA-B27, were highlighted.