BACKGROUND: Scotland's HCV elimination strategy has focused efforts on scaling up treatment in community-based settings, with population-based surveys indicating substantial reductions in HCV prevalence among people who inject drugs. We aimed to evaluate progress against World Health Organization (WHO) elimination targets using a national virtual cohort of individuals in contact with drug services in Scotland.

METHODS: The cohort was formed utilizing national administrative databases (including opioid agonist therapy prescribing, drug-related hospitalizations and specialist drug treatment) and linked to HCV databases to ascertain diagnosed infection status during January 2015-March 2024. Multi-state and logistic regression models were used to estimate undiagnosed infection among individuals not tested during follow-up.

RESULTS: Among 78,444 individuals who attended drug services, 15,851 (20.2%) had died or migrated during follow-up. Among 62,593 remaining in the prevalent cohort, 12,553 had been diagnosed with HCV, with 86.8% treated. We estimated 2415 (95% CI 1827-3467) individuals had undiagnosed HCV; thus, 83.2% (77.0%-86.9%) of infection had been diagnosed. Prevalence decreased by an estimated 71.7% (66.0%-75.1%), accounting for estimated undiagnosed infection. During January 2015-March 2024, estimated (diagnosed and undiagnosed) HCV incidence was 1.73 (1.56-2.05) and 2.13 (1.97-2.46) per 100 person-years for the overall cohort and those with a recent opioid-related drug service attendance, respectively.

CONCLUSIONS: Scotland has made significant progress towards HCV elimination targets, with high levels of diagnosis and treatment achieved among people in contact with a broad range of drug services. Further, we demonstrate that linkage of administrative data has an important role to play in evaluating progress on HCV elimination.