Clinical burden of HDV in Spain: Incidence, prevalence, and associated comorbidities

HDV leads to the most severe form of viral hepatitis. It has been estimated to affect 5-13% of people who have chronic HBV worldwide. Evidence of HDV incidence, prevalence, and disease burden in Spain is limited. The purpose of this study is to evaluate the clinical burden of HDV in Spain by assessing the incidence, prevalence, and baseline demographics and comorbidities of patients with HDV infection compared with those with HBV monoinfection.

Adults (≥18 years) with ≥1 International Classification of Disease-9/10-Clinical Modification diagnosis code for HDV or HBV in the Spanish National Health System's Hospital Discharge Records Database from January 1, 2000, to December 31, 2019, were identified. HDV prevalence and incidence were calculated. Baseline (duration before index disease) patient characteristics and comorbidities were assessed.

The estimated prevalence of adults with HDV infection among those with HBV was 4.9%, with an incidence of 4.5% over the study period. Adults with HDV infection were significantly younger than those with HBV monoinfection (mean [SD] age 42.7 [14.4] vs. 46.6 [15.9] years, p = 0.0034). Adults with HDV infection reported significantly higher rates of concomitant hepatitis C infection (8.8% vs. 3.6%; p = 0.0043), HIV infection (13.8% vs. 3.3%; p <0.0001), and substance use disorder (18.9% vs. 7.0%; p <0.0001) compared with those with HBV monoinfection.

Adults with HDV infection who attended hospitals in Spain have a high comorbidity burden and conditions associated with potentially modifiable behaviors. Novel treatment strategies are needed to reduce morbidity rates among adults with HDV infection in Spain.

Adults with HDV infection who attended hospitals in Spain had a high comorbidity burden and conditions associated with potentially modifiable behaviors (i.e. sexually transmitted diseases and substance abuse). Given the high prevalence of HDV in Spain, these comorbid conditions may contribute to a larger healthcare burden. Chronic HDV infection is also considered the most severe form of viral hepatitis, with a reported mortality rate of 40% in adults with HDV infection. These findings emphasize the importance of enhanced HDV screening in patients with chronic HBV, along with early diagnosis and the prompt initiation of antiviral therapies to manage disease progression and reduce the risk of liver-related morbidity and mortality.