Quantiferon TB-Gold conversion can predict active tuberculosis development in elderly nursing home residents

Abstract

AimThe study was carried out on elderly nursing home residents in Taiwan. We assessed whether the serial QuantiFERON-TB Gold (QFT-G) assay and serial tuberculin skin test (TST) were reliable tools to predict or exclude the development of active tuberculosis (TB). MethodsThis prospective observational cohort study involved non-bacillus Calmette-Guerin-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 5years. Agreement between QFT-G and TST, incidence rate ratio, positive predictive value, and negative predictive value for progression to active TB were measured. ResultsDuring 5-year follow up, three participants developed active TB. The agreement between these two tests was 54.13% (?=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. ConclusionIn 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.