Kinetics of quantitative hepatitis B surface antigen in patients with rheumatic disease and chronic hepatitis B receiving biologic agents.

The effect of biologic treatment on quantitative Hepatitis B surface Antigen (qHBsAg) levels and HBsAg clearance in rheumatic patients with chronic HBV infection has not been well studied. We prospectively followed rheumatic patients with HBeAg-negative chronic HBV infection (n = 28) treated with biologics and oral antivirals, categorized into patients with chronic hepatitis B (CHB, group A n = 13) and chronic HBV infection (group B n = 15) and matched them to appropriate non-rheumatic controls. qHBsAg kinetics were serially measured and compared between groups. No HBV reactivation (HBVr) was recorded during the 108.25 patient-year follow-up. Among patients with CHB, the annual rapid qHBsAg decline (i.e. decline >0.5 log10  IU/mL/year) as well as HBsAg clearance did not differ between rheumatic patients [n = 4 (32.7%), n = 1 (7.7%)] and controls [n = 6 (28.4%), p = .726 and n = 2 (7.7%), p = .818, respectively]. In contrast, there was a slower annual qHBsAg decline in rheumatic patients with chronic HBV compared to non-rheumatic controls (-0.04 vs -0.13 log10  IU/mL at year 1, p = .019) with no cases of rapid qHBsAg decline or HBsAg clearance in rheumatic patients (0%) compared to a cumulative incidence of 24% and a rate of 20%, respectively in controls. In biologic-treated rheumatic patients with HBeAg-negative HBV receiving antiviral prophylaxis, there was slower qHBsAg decline, lower cumulative rates of rapid qHBsAg decline and HBsAg clearance compared to non-rheumatic controls.