. 2021 Jul 28;9(1):10.1128/spectrum.00096-21. doi: 10.1128/spectrum.00096-21

TABLE 3.

QuantiFERON-TB indeterminate results

Parameter^d	1-tube-QFT-plus	4-tube-QFT-plus	QFT-GIT
Total no. of samples	1.9 million	0.3 million	0.1 million
Total no. of indeterminate results	15,671	13,938	3,023
Total % indeterminate results (95% CI)	0.83 (0.81, 0.84)	4.2 (4.18, 4.32)	2.7 (2.63, 2.82)
% Indeterminate results due to low mitogen (+ control)^a (95% CI)	80 (79.5, 80.7)	98 (97.3, 97.8)	95 (93.8, 95.4)
% Indeterminates due to high nil (− control)^b (95% CI)	12.3 (11.76, 12.79)	1.4 (1.22, 1.62)	3.6 (2.94, 4.27)
% Indeterminates due to high – and high + control^c (95% CI)	7.6 (7.2, 8.03)	1 (0.84, 1.17)	1.5 (1.03, 1.88)

Nil tube ≤8 IU/ml and mitogen <0.5 IU/ml.

Nil tube >8 IU/ml and mitogen <0.5 IU/ml.

Nil tube >8 IU/ml and mitogen ≥0.5 IU/ml.

CI, confidence interval.