The mean attributable health care costs associated with hepatitis B virus in Ontario, Canada: A matched cohort study.

Background: No Canadian studies examined the economic impact of hepatitis B virus (HBV) using population-based, patient-level data. We determined attributable costs associated with HBV from a health care payer perspective. Methods: We conducted an incidence-based, matched cohort, cost-of-illness study. We identified infected subjects (positive HBV surface antigen, DNA, or e-antigen) between 2004 and 2014, using health administrative data. The index date was the first positive specimen. The cohort was organized into three groups: no HBV-related complications, HBV-related complications before index date, and HBV-related complications post-index date. To evaluate costs (2017 Canadian dollars), we adopted the phase-of-care approach defining six phases. Mean attributable costs were determined by evaluating mean differences between matched pairs. Hard match variables were sex, age group, index year, rurality, neighbourhood income quintile, comorbidities, and immigrant status. Costs were combined with crude survival data to calculate 1-, 5-, and 10-year costs. Results: We identified 41,469 infected subjects with a mean age of 44.2 years. The majority were males (54.7%), immigrants (58.4%), and residents of major urban centres (96.8%). Eight percent had HBV-related complications before index date and 11.5% had them post index date. Across groups, mean attributable costs ranged from CAD $27-$19 for pre-diagnosis, CAD $167-$1,062 for initial care, CAD $53-$407 for continuing care, CAD $1,033 for HBV-related complications, CAD $304 for continuing care for complications, and CAD $2,552-$4,281 for final care. Mean cumulative 1-, 5-, and 10-year costs ranged between CAD $253-$3,067, $3,067-$20,349, and $6,128-$38,968, respectively. Conclusions: HBV is associated with long-term economic burden. These results support decision-making on HBV prevention and monitoring strategies.