Applying the COM-B Model to Identify Barriers to Bulevirtide Adherence in Chronic Hepatitis D: A Multicenter Italian Study

Adherence to treatment is a key determinant of clinical outcomes in chronic infectious diseases, including hepatitis D virus (HDV) infection. Even if bulevirtide (BLV) has shown a promising adherence profile in clinical trials, adherence is often compromised by various barriers in the context of HDV—especially among migrant populations. The aim of this study was to investigate the factors influencing adherence to BLV treatment in real-life settings in Italy. From May to September 2024, two anonymous surveys—one for HDV patients undergoing bulevirtide (BLV) treatment and one for their hepatologists—were conducted across five tertiary centers in Italy. The study employed the COM-B model (Capability, Opportunity, Motivation–Behaviour) to systematically explore the behavioural drivers influencing treatment adherence in this population and unmet needs. Of the 86 consecutive adult patients receiving bulevirtide (BLV) who were invited to participate, 83 (97%) completed the multilingual survey (35% > 60 years old, 48% Italians; 80% under BLV > 6 months) and were included in the analysis, together with 13 hepatologists. The findings revealed key challenges related to patient education, logistical access to medication, and psychological factors affecting motivation. Specifically, 10% had considered discontinuing treatment and 10% admitted to having missed doses. A deeper understanding of these multifactorial determinants may aid in the development of targeted interventions to enhance adherence and achieve personalized therapeutic outcomes for individuals living with HDV.