Data are presented in IU·mL⁻¹. For the QuantiFERON®-TB Gold (QFT-G) test (Cellestis, Carnegie, Australia) performed in May 2005, 6 mL whole blood was drawn into a heparinised blood collection tube and transported to the National Reference Laboratory for Mycobacteriology at the Statens Serum Institute (Copenhagen, Denmark). The blood samples were divided into four aliquots and stimulated in a 24-well culture plate (Nunc, Roskilde, Denmark) with saline, phytohaemaglutinin (PHA) or Mycobacterium tuberculosis-specific peptides (early secreted antigenic target (ESAT)-6 or culture filtrate protein (CFP)-10). For the QFT-G in-tube (QFT-GIT) test performed in September 2006, three whole-blood samples, each 1 mL, were drawn directly into vacutainer tubes coated with saline, PHA or M. tuberculosis-specific peptides (ESAT-6, CFP-10 and TB7.7). The tubes were incubated at the hospital for 18 h at 37^°C and the plasma was harvested. ELISA was performed according to the manufacturers’ instructions and software.