National Health Insurance Expenditure and Health-System Use for Hepatitis B and C in Bulgaria, 2021–2025

Background: National reimbursement records complement model-based estimates of hepatitis treatment costs. Our primary objective was to quantify Bulgarian National Health Insurance Fund (NHIF) antiviral reimbursement and its price and quantity components; secondary objectives were to estimate dispensing-based treatment volume and describe service activity. Methods: This retrospective study analysed aggregated national pharmacy records for complete years 2021–2025 and hospital and outpatient records for complete years 2024–2025. Diagnosis-identified records were combined with product-identified antiviral prescriptions under fibrosis or cirrhosis codes. Fisher indices decomposed expenditure; seasonal quasi-Poisson models with Newey–West standard errors described monthly trends. Results: Antiviral reimbursement totalled EUR 101.5 million, including EUR 91.6 million for HCV and EUR 10.0 million for HBV. Annual antiviral reimbursement increased from EUR 18.9 million to EUR 21.7 million. The budget share for all pharmacy products in the hepatitis case definition, including adjunctive products, declined from 3.99% to 2.61%. Relative to 2021, the 2025 Fisher price and quantity indices were 0.799 and 1.395 for HBV and 0.885 and 1.447 for HCV. Estimated mean continuous HBV therapy increased from 2226 to 3051 people; HCV standard-course equivalents increased from 604 to 777, with duration-based ranges of 431–607 and 571–777. These estimates do not identify unique treated patients. Annualised inpatient-episode trends during 2024–2025 were 9.2% for HBV and −7.4% for HCV; consultation trends were 3.7% and −6.9%. Conclusions: Dispensed treatment volume increased while reimbursed unit prices and the hepatitis pharmaceutical budget share declined. These findings describe payer expenditure and encounters; they do not establish improved affordability, access, or treatment coverage.