Incidence of Viral Hepatitis D Relapses Upon Discontinuation of Bulevirtide in Patients With Chronic Hepatitis D and Negative HDV RNA

This observational study will be conducted in patients with chronic co-infection with hepatitis B and D viruses, with negative PCR for HDV RNA in peripheral blood and no signs of active liver inflammation according to blood chemistry parameters, receiving background therapy with bulevirtide for more than 48 weeks and liver biopsy performed or prescribed to be performed as part of routine practice. After the patient has signed the Informed Consent, a portion of the liver biopsy collected as part of routine practice will be sent to the laboratory for PCR testing for HDV RNA, background therapy with bulevirtide will be interrupted, and the patient will be observed in the clinic in accordance with routine medical practice, but at least once times every 4 weeks, for timely detection of relapse of the hepatitis D and initiation of antiviral therapy. Once a relapse of viral hepatitis D is determined via the PCR HDV RNA, the patient's participation in the study will be terminated. The collected data will be analyzed to assess the probability of relapse-free over time. Separate tests will also be conducted for subgroups of patients based on covariates such as duration of previous background therapy with bulevirtide, duration of HDV suppression, use of any other concomitant antiviral therapy during bulevirtide treatment.