Cost Effectiveness of Preventive Treatment for Tuberculosis in Special High-Risk Populations

In view of the goal of eliminating tuberculosis (TB) by 2050, economic evaluations of interventions against the development of TB are increasingly requested. Little research has been published on the incremental cost effectiveness of preventative therapy (PT) in groups at high risk for progression from latent TB infection (LTBI) with Mycobacterium TB (MTB) to active disease. A systematic review of studies with a primary focus on model-driving inputs and methodological differences was conducted.

A search of MEDLINE, the Cochrane Library and EMBASE to July 2014 was undertaken, and reference lists of eligible articles and relevant reviews were examined.

A total of 876 citations were retrieved, with a total of 24 studies being eligible for inclusion, addressing six high-risk groups other than contact persons. Results varied considerably between studies and countries, and also over time. Although the selected studies generally demonstrated cost effectiveness for PT in HIV-infected subjects and healthcare workers (HCWs), the outcome of these analyses can be questioned in light of recent epidemiologic data. For immigrants from high TB-burden countries, patients with end-stage renal disease, and the immunosuppressed, now defined as further vulnerable groups, no consistent recommendation can be taken from the literature with respect to cost effectiveness of screening and treating LTBI. When the concept of a fixed willingness-to-pay (WTP) threshold as a prerequisite for final categorization was used, the sums ranged between 'no specification' and US$100,000 per quality-adjusted life-year.

To date, incremental cost-effectiveness analyses on PT in groups at high risk for TB progression, other than contacts, are surprisingly scarce. The variation found between studies likely reflects variations in the major epidemiologic factors, particularly in the estimates on the accuracy of the tuberculin skin test (TST) and interferon-gamma release assays (IGRA) as screening methods used before considering PT. Further research, including explicit evaluation of local epidemiological conditions, test accuracy, and methodology of WTP thresholds, is needed.