Screening new prisoners for tuberculosis may not be cost-effective

Tuberculosis (TB) remains more common in people who are incarcerated than in the general population, and the World Health Organization recommends systematic screening in these settings. Despite this, people arriving at prisons in England are not routinely tested for TB infection, and there has been little information about whether introducing such screening would be a sensible use of health care resources. To fill that gap, a research team led by Peter J. Dodd carried out a model-based cost-effectiveness analysis of offering systematic TB infection screening to everyone at first reception into English prisons. The study took a health systems perspective, meaning it considered costs and outcomes relevant to the health services that would deliver and follow up on screening and care. The researchers used existing public data about the number of people in prison and the patterns by which people enter and leave (stocks and flows) to calibrate a tuberculosis transmission model, and they combined that with detailed decision tree models of the prison-specific care pathways and the costs associated with those steps. Stakeholders and pilot studies helped shape realistic assumptions about how screening and follow-up would work in practice. The study was funded by UKHSA.

The team built a transmission model of TB adjusted to public records on prison populations and flows, and they developed decision-tree representations of the specific steps someone would take through prison tuberculosis care and the costs of those steps. With those tools they estimated the health gains and costs of adding systematic TB infection screening at first reception, and calculated incremental cost-effectiveness ratios (ICERs) expressed as cost per quality-adjusted life-year (QALY) gained. In the base-case analysis the ICER for universal screening and preventive treatment was £78,000 per QALY gained—well above the commonly used benchmark of £30,000 per QALY. The researchers then examined alternative scenarios. Reducing loss to follow-up (LTFU) in the care cascade improved cost-effectiveness to about £70,000 per QALY, and eliminating extramural escort costs (the costs of taking prisoners to outside healthcare appointments) improved the figure to about £54,000 per QALY. Importantly, when screening was targeted only to people born in countries with higher TB incidence (more than 40 cases per 100,000 people per year), the model predicted that the strategy would be cost-saving.

The findings point to a practical conclusion for policy makers: offering TB infection screening and preventive treatment to every person admitted to English prisons is unlikely to represent good value for money under the usual threshold of £30,000 per QALY. However, selective approaches that focus on people at higher risk—such as those born in countries with higher TB incidence—could both improve health outcomes and save money. The analysis also highlights operational levers that could make a universal approach more attractive: reducing loss to follow-up in the care cascade and avoiding the extra costs associated with taking people out of prison for healthcare (extramural escort costs) both move the economics in a better direction. For prison health services and public health bodies, the study suggests that careful targeting and system improvements may be necessary to meet the needs of those incarcerated while keeping spending under control. The work, led by Peter J. Dodd and funded by UKHSA, offers evidence to inform decisions about where to direct limited resources and how to redesign services to be both effective and affordable.