Economic Evaluation of Screening Strategy for Latent Tuberculosis Infection (LTBI) in Contacts of Tuberculosis Patients: Systematic Review and Quality Assessment.

A tuberculin skin test (TST) or interferon-gamma release assay (IGRA) can be used to screen for latent tuberculosis infection (LTBI). Due to its low cost, TST has been used particularly in underdeveloped countries. The limitations of TST were poor specificity in populations with a high prevalence of Bacille Calmette-Guérin (BCG) vaccination and variability of test readers. IGRA is used as an alternative to TST in settings where higher costs can be supported. The lack of studies conducted in high TB incidence countries since previous review, and using relevant assessment tools of the quality appraisal make the need for updated studies and a more comprehensive systematic review. This study aimed to conduct a systematic review of published economic evaluations of screening strategies for LTBI in contacts of TB patients, assess the quality of these studies, and compare the assessment results related to a country's income level in order to provide information to other countries. The databases were searched in January 2022 including MEDLINE and Scopus. Two independent reviewers evaluated the included studies based on eligibility criteria, data extraction, and quality assessment. Eleven economic evaluations of LTBI diagnostic tests in TB contacts were included. Most studies were conducted in high-income countries (91%) and used cost-effectiveness analysis methods (73%). The quality assessment of reporting and data sources was appropriate, ranging from 71% to 89%. Interventions varied from study to study. The outcomes were cost per life years gained (27%), cost per quality-adjusted life year gained (27%), cost per TB case prevented (36%), and cost per close contact case (10%). In high-income countries which were not countries with high TB burden, the use of IGRA alone for screening TB contacts was cost-effective, whereas TST was cost-effective in only two studies. In comparison to TST, IGRA could reduce false-positive results, resulting in fewer patients undergoing TB treatment and preventive treatment.