Modelling the cost-effectiveness of strategies to prevent tuberculosis in child contacts in a high-burden setting.

BACKGROUND

WHO recommends isoniazid preventive therapy (IPT) for young children in close contact with an infectious tuberculosis (TB) case. No models have examined the cost effectiveness of this recommendation.

METHODS

A decision analysis model was developed to estimate health and economic outcomes of five TB infection screening strategies in young household contacts. In the no-testing strategy, children received IPT based on age and reported exposure. Other strategies included testing for infection with a tuberculin skin test (TST), interferon γ release assay (IGRA) or IGRA after TST. Markov modelling included age-specific disease states and probabilities while considering risk of re-infection in a high-burden country.

RESULTS

Among the 0-2-year-old cohort, the no-testing strategy was most cost effective. The discounted societal cost of care per life year saved ranged from US$237 (no-testing) to US$538 (IGRA only testing). Among the 3-5-year-old cohort, strategies employing an IGRA after a negative TST were most effective, but were associated with significant incremental cost (incremental cost-effectiveness ratio >US$233 000), depending on the rate of Mycobacterium tuberculosis infection.

CONCLUSION

Screening for M tuberculosis infection and provision of IPT in young children is a highly cost-effective intervention. Screening without testing for M tuberculosis infection is the most cost-effective strategy in 0-2-year-old children and the preferred strategy in 3-5-year-old children. Lack of testing capacity should therefore not be a barrier to IPT delivery. These findings highlight the cost effectiveness of contact tracing and IPT delivery in young children exposed to TB in high-burden countries.