Table 3

Conditional specificities of the tests, assessed in 1825 bTB-free cattle

TestProportion of bTB-free cattle with a negative result to the testConditional specificity: mean and 95% CI
SICCTD421627/182589.15% (87.72% to 90.58%)
IFND3841/1825
(negative results only)
46.08% (43.80% to 48.37%)
(negative results only)
1505/1825
(negative and inconclusive results)
82.47% (80.72% to 84.21%)
(negative and inconclusive results)
IFND421108/1825
(negative results only)
60.71% (58.47% to 62.95%)
(negative results only)
1707/1825
(negative and inconclusive results)
93.53% (92.41% to 94.66%)
(negative and inconclusive results)
PPDD3707/1567*45.12% (42.65% to 47.58%)
PPDD421116/1775†62.87% (60.63% to 65.12%)
MIXD31571/182586.08% (84.49% to 87.67%)
MIXD421719/182594.19% (93.12% to 95.26%)
  • CIs were calculated with Excel.

  • *On day 3, 258 results were not interpretable on the PPD basis only.

  • †On day 42, 50 results were not interpretable on the PPD basis only.

  • D3, day 3; D42, day 42; IFN, gamma-interferon test with results interpreted using both PPD and MIX (see table 1); MIX, specific antigens ESAT-6 and CFP-10; PPD, purified protein derivatives; SICCT, single intradermal cervical comparative test.