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cost-saving if the price is lower than the $36 in our model. This could be achieved by negotiating with manufacturers to lower the cost with bulk orders. This study has certain limitations. Firstly, for simplicity, we
assumed 100% specificity and sensitivity of QFT-G, although the documented specificity of QFT-G ranges from 98% to 100%,16 and sensitivity ranges between 81% and 87%.16,30 This could reduce the cost-effectiveness of screening, due to fewer positive tests and fewerHCWstreated for LTBI.31 However, no existing LTBI test meets 100% sensitivity and specificity, whereas the other option, a tuberculin test, has an even lower sensitivity and specificity. However, reports of nosocomial TB in theliteraturetendtoinvolve large-scale or drug-resistant cases, which limits the relevance to our Singapore setting. Furthermore, it is challenging to determine the duration and extent of exposure required for transmission in the community, let alone in a hospital setting, where shift work is prevalent. Secondly, neither nosocomial active TB transmission nor death due to INH-induced hepatitis/active TB were included in the model. However, the incidence of death due to INH-hepatitis is very low in the general literature32 and has been historically zero among HCWs in this hospital, as with deaths from active TB. Altogether, our study provides insights on the effectiveness,
efficiency, and budget impact of LTBI screening strategies among HCWs. We found that LTBI screening strategies can be cost-effective if HCWs are risk-stratified according to their country of origin and area of work. Furthermore, the efficiency of screening could be further improved if health systems ensure adherence to LTBI testing and treatment, and could even be cost-saving if the cost of QFT-G were decreased. These strate- gies targeting LTBI screening in HCWs in intermediate-TB bur- den countries should be considered in the effort to prevent nosocomial TB transmission.27,31
Acknowledgments. Financial support. No financial support was provided relevant to this article.
Conflicts of interest. All authors report no conflicts of interest relevant to this article.
Supplementary material. To view supplementary material for this article, please visit
https://doi.org/10.1017/ice.2018.334.
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