The Seroprevalence, Risk Factors, and Clinical Profile of Hepatitis D in Omani Patients with Chronic Hepatitis B: A Multicenter Cross-Sectional Study

<b>Background</b>: Since the introduction of the hepatitis B virus (HBV) vaccination program in Oman in 1990, the HBV prevalence has markedly decreased. However, hepatitis D virus (HDV) infection, which is associated with progressive liver disease in patients with chronic HBV, remains understudied in the Omani population. This study aimed to estimate HDV's seroprevalence, characterize its virological and clinical features, and identify factors associated with anti-HDV positivity among adult Omani patients with chronic HBV infection. <b>Methods</b>: We conducted a multicenter cross-sectional study in 2024 at two referral hospitals and two polyclinics in Oman. Adult Omani patients with chronic HBV (HBsAg-positive for >6 months) were enrolled. Demographic, clinical, laboratory, imaging, and elastography data were collected. The total anti-HDV antibodies were tested using an ELISA; HDV RNA was tested for anti-HDV-positive or equivocal results. Liver Fibrosis was assessed non-invasively through liver stiffness measurement (LSM) using vibration-controlled transient elastography (VCTE); FibroScan^® and clinical evaluation. Ridge (penalized) logistic regression identified predictors independently associated with anti-HDV positivity. <b>Results</b>: Among 639 patients (59.3% male; mean age of 46.6 ± 8.8 years), 36 patients were anti-HDV-positive, resulting in an HDV seroprevalence of 5.6% (95% CI: Exact 3.98-7.71; Wilson 4.10-7.70). Only one anti-HDV-positive patient had detectable HDV RNA, which became undetectable on follow-up without HDV treatment. The anti-HDV-positive patients were more frequently female and had a higher frequency of prior blood transfusions. In a penalized multivariable analysis, blood transfusions were independently associated with anti-HDV positivity (OR of 19.94), whereas male sex was associated with lower odds of being anti-HDV-positive (OR of 0.15). All the anti-HDV-positive patients had mild fibrosis (F0-F1). <b>Conclusions</b>: Our study demonstrated an anti-HDV prevalence of 5.63% among adult Omani patients with chronic HBV infection, while active viremia appeared to be rare. Blood transfusions were the main identified risk factor. Given the very low HDV viremia, targeted screening of higher-risk groups may be efficient.