Cost-effectiveness of mass screening for Hepatitis C virus among all inmates in an Irish prison

Background: In Irish prisons, there is a high proportion of people who inject drugs (PWID; 26%) and a high prevalence of HCV (16%), making prison a high priority setting for HCV testing and treatment. We evaluate the cost-effectiveness of a mass HCV screening intervention in Mountjoy Prison, Dublin, compared to the standard-of-care of intermittent screening on committal. Methods: Primary cost data was collected from the intervention using an overall provider perspective. Standard-of-care (SOC) costs were estimated through interview. All costs were inflated to 2020 Euros. An HCV transmission and disease progression model among incarcerated and community PWID and ex-injectors was calibrated to the Dublin HCV epidemic, allowing inclusion of population-level health benefits. The model used intervention data, suggesting 419 individuals were screened, 50 HCV infections diagnosed and 32 individuals initiated treatment, to project the resulting costs and health benefits (quality adjusted life years or QALYs) over 50 years with 5% discounting. The incremental cost effectiveness ratio (ICER), cost per QALY gained, was estimated for the screening intervention compared to the standard-of-care. Probabilistic sensitivity analyses (PSA) determined the probability that the intervention was cost-effective compared to a willingness-to-pay threshold of (sic)30,000/QALY as used in Ireland. The ICER for 1- or 3-yearly mass screening in all Dublin prisons was also calculated. Results: The total direct costs of the intervention (not including treatment drug costs) was (sic)82,392, with most costs being due to staff(43%) and overhead or management costs (38%). Despite having little epidemiological impact due to the small numbers treated, over 50 years the incremental cost of the intervention was (sic)36,592 and 3.8 QALYs were gained, giving a mean ICER of (sic)9,552/QALY. The majority (84%) of PSA runs were below the willingness-to-pay threshold. Yearly mass screening had an ICER of (sic)2,729/QALY compared to SOC and gave a higher net monetary benefit ((sic)7,393,382) than screening every 3 years ((sic)6,252,816). Conclusion: Prison mass screening could be a cost-effective initiative for increasing testing and treatment of HCV in Ireland.