Impact of fatty liver disease on hepatic function and fibrosis progression in chronic hepatitis B patients: a narrative review

Chronic hepatitis B (CHB) and fatty liver disease (FLD) are significant global health concerns that frequently coexist, posing complex challenges for clinical management and research. CHB, caused by persistent infection with the hepatitis B virus (HBV), affects approximately 296 million individuals worldwide, leading to progressive liver damage, fibrosis, and hepatocellular carcinoma. Concurrently, FLD, encompassing non-alcoholic fatty liver disease and alcoholic fatty liver disease, has become the most prevalent chronic liver disease globally due to the increasing prevalence of metabolic syndrome and obesity. The coexistence of CHB and FLD is particularly concerning, as both conditions independently contribute to hepatic dysfunction and fibrosis through distinct yet overlapping mechanisms, including immune-mediated injury, oxidative stress, and metabolic dysregulation. This narrative review examines the interplay between FLD and CHB, focusing on the impact of FLD on hepatic function and fibrosis progression in CHB patients. Key mechanisms underlying this interaction, such as the modulation of HBV replication, exacerbation of inflammatory pathways, and activation of fibrogenic processes, are explored. Diagnostic and therapeutic challenges in this dual disease state are discussed, with an emphasis on the limitations of current tools in distinguishing overlapping pathologies and the influence of FLD on antiviral therapy outcomes. The review highlights the need for multidisciplinary approaches to managing CHB and FLD and underscores the importance of targeted research to address gaps in knowledge. By elucidating the mechanisms and clinical implications of CHB–FLD comorbidity, this review aims to inform improved diagnostic strategies, individualized therapeutic interventions, and future research directions.