TB screening is highly cost-effective in young children

Approximately 2 billion individuals worldwide are infected with Mycobacterium tuberculosis, according to the World Health Organization. "This reservoir of infected people, together with ongoing exposure in areas with poor tuberculosis (TB) control, lead to 9 million new TB cases and 2 million deaths annually," write Anna M. Mandalakas, MSEpi, from Baylor College of Medicine, Texas Children’s Hospital, Houston, and colleagues. "Children carry 15% of the global disease burden, leading to approximately 1 million cases of childhood TB annually."

Although the World Health Organization recommends giving IPT to young children who are in close contact with a case of infectious TB, researchers have not previously assessed whether this recommendation is cost-effective. Therefore, the investigators developed a decision analysis model to evaluate health and economic outcomes of 5 TB infection screening strategies for such children. The no-testing strategy was to administer IPT on the basis of age and reported exposure; other strategies included tuberculin skin test (TST) for infection, interferon G release assay (IGRA), or IGRA after TST.

Once children completed screening, Markov modeling allowed consideration of IPT efficacy, reinfection and subsequent disease, and mortality in children who did and did not receive IPT.

The no-testing strategy was most cost-effective for children aged 2 years or younger, with discounted societal cost of care per life year saved of US$237 compared with US$538 for IGRA-only testing. For children aged 3 to 5 years, strategies using IGRA after a negative TST were most effective. Depending on the rate of M tuberculosis infection, however, these strategies were associated with significant incremental cost and an incremental cost-effectiveness ratio exceeding US$233,000.

"Screening for M tuberculosis infection and provision of IPT in young children is a highly cost-effective intervention," the study authors write. "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."

Limitations of this model include derivation of test performance estimates from studies examining test accuracy for the identification of TB disease and the assumption that IPT usage was similar across strategies. The model underestimates the effect of an ideal contact tracing program offering IPT after every TB exposure.

"Our realistic model illustrates that blanket IPT programmes typical of TB high-burden settings are cost effective despite well recognised deficiencies, including low rates of IPT usage and missed opportunities to provide IPT for serial exposures," the authors conclude. "The impact and cost effectiveness of these programmes could surely be enhanced by raising IPT uptake and adherence, and decreasing missed opportunities to provide IPT.... [O]ur findings highlight the need for intensified contact tracing and improved IPT delivery to all TB-exposed children living in TB high-burden settings."

The Thrasher Research Fund supported this project. Dr. Mandalakas received salary support from the US Department of State to serve as a Senior Fulbright Scholar to South Africa during the completion of this analysis. The other authors have disclosed no relevant financial relationships.

Thorax. 2013;68:247-255. Abstract

Source: Medscape Today