Recommendations for the diagnosis of patients with hepatitis delta virus (HDV) in Spain.

The hepatitis delta virus (HDV), whose infection depends on the presence of the hepatitis B virus (HBV), is associated with one of the chronic viral hepatitis that most rapidly progresses to advanced liver disease, including liver cirrhosis and/or hepatocellular carcinoma. In this context, screening for HBV/HDV infection is key to the early diagnosis of hepatitis D, improving the prognosis of infected individuals through a strategy that has proven to be effective and efficient. This document reviews the epidemiology and current situation of hepatitis D in Spain, including the main barriers to its detection and diagnosis. The aim is to define recommendations for the diagnosis of hepatitis D, determined by a multidisciplinary experts panel. Regarding screening, recommendations are established in relation to: 1) settings and populations where screening is indicated; 2) optimization of HDV detection (reflex testing and point-of-care testing); and 3) the frequency for the test to be repeated. Regarding diagnosis, the following aspects are addressed: 1) how to diagnose HDV infection (double reflex test); 2) what characteristics are present in the tests currently available to determine HDV-RNA; and 3) possible solutions to overcome the current barriers in the diagnosis of the infection. These recommendations contribute to improving the prognosis for hepatitis D and, additionally, represent a step toward eliminating viral hepatitis by 2030, a goal set by the World Health Organization.