Quantiferon TB ‐ G old conversion can predict active tuberculosis development in elderly nursing home residents

Aim The study was carried out on elderly nursing home residents in T aiwan. We assessed whether the serial QuantiFERON ‐ TB G old ( QFT ‐ G ) assay and serial tuberculin skin test ( TST ) were reliable tools to predict or exclude the development of active tuberculosis ( TB ). Methods This prospective observational cohort study involved non‐bacillus C almette– G uérin‐vaccinated 259 elderly nursing home residents free of active TB at baseline. Of these, 147 were eligible for follow up. Participants underwent serial QFT ‐ G and TST at baseline and 2‐year follow up, and were monitored for active TB over 5 years. Agreement between QFT ‐ G and TST , incidence rate ratio, positive predictive value, and negative predictive value for progression to active TB were measured. Results During 5‐year follow up, three participants developed active TB . The agreement between these two tests was 54.13% (ĸ = 0.167, P  = 0.001). The incidence rate ratio was 15.8 ( P  = 0.016) for the QFT ‐ G ‐conversion group compared with the TST ‐positive group at baseline. Positive predictive value for QFT ‐ G conversion groups was 25%. Negative predictive value was 100% for the TST ‐negative group at baseline. Conclusion In the elderly nursing home residents, QFT ‐ G conversion is a more reliable tool to predict the development of active TB . Meanwhile, TST is a valuable tool for predicting the chance of not developing active TB . Geriatr Gerontol Int 2015; 15: 1179–1184.