Temporal Patterns of HBV Reactivation in Rituximab-Treated CKD Patients: An Exploratory Analysis of Baseline Quantitative HBsAg and Prophylaxis Duration.

BACKGROUND: Hepatitis B virus (HBV) reactivation is a severe complication in HBsAg-positive patients receiving rituximab (RTX) for chronic kidney disease (CKD). We evaluated clinical predictors of reactivation, optimal prophylaxis duration, and post-discontinuation risk kinetics. METHODS: We retrospectively analyzed 105 HBsAg-positive CKD patients treated with RTX. Participants were stratified by antiviral prophylaxis duration: Group A (≥ 12-18 months post-RTX, n=41), Group B (6-12 months, n=47), and Group C (< 6 months, n=17). Reactivation rates and risk factors were analyzed using univariate logistic regression, log-rank test and Kaplan-Meier survival curves. RESULTS: The overall HBV reactivation was 7.6% (8/105). A significant "duration-dependent" protective effect was observed, with reactivation rates of 2.4%, 6.4%, and 23.5% in Groups A, B, and C, respectively (P = 0.012). Baseline HBsAg > 2.4 log10 IU/mL (OR = 12.5, P = 0.005) and antiviral prophylaxis duration < 6 months (OR = 6.8, P = 0.023) emerged as noteworthy clinical factors closely linked to reactivation risk. Furthermore, Kaplan-Meier curves confirmed a distinct temporal clustering of reactivation between 4 and 10 months following prophylaxis cessation. CONCLUSIONS: An extended 12-18 months antiviral prophylaxis regimen provides optimal protection against HBV reactivation in CKD patients. Baseline HBsAg > 2.4 log10 IU/mL represents a noteworthy marker of heightened risk. Due to the limitations of a small event size, these findings remain exploratory and hypothesis-generating. Crucially, the observed temporal clustering between 4 and 10 months indicates a distinct post-prophylaxis risk timeline compared to non-renal populations, highlighting the need for further tailored, prospective validation.