Table 2. Agreement between IGRA and TST using different cut-off values of TST.

		One-step TST						Two-step TST
		≥10 (mm)*			≥11 (mm)*	≥13 (mm)*	≥15 (mm)*	≥10 (mm)*
			BCG (−)**	BCG (+)**
TST+/IGRA+ (n)		114	44	39	102	86	69	119
TST+/IGRA- (n)		49	14	27	30	21	13	58
TST-/IGRA+ (n)		21	8	8	33	49	66	16
TST-/IGRA- (n)		71	33	23	90	99	107	62
Agreement, %		72.5	77.8	63.9	75.3	72.5	69.0	71.0
Kappa (SE)		0.44 (0.06)	0.55 (0.10)	0.29 (0.09)	0.50 (0.06)	0.46 (0.06)	0.39 (0.06)	0.41 (0.06)
Symmetry test***	Chi-squared value	11.2	1.64	10.3	0.14	11.2	35.6	23.8
	p value	0.0008	0.20	0.0013	0.71	0.0008	<0.0001	<0.0001

IGRA: Interferon-gamma release assay; TST: Tuberculin skin test; SE: Standard error; BCG (−): Without history of BCG vaccination; BCG (+): With history of BCG vaccination;

^*N = 255; all subjects with valid data sets.

^**N = 99 and 97 for BCG (−) and BCG (+) groups, respectively.

^***Equivalent to McNemar test for evaluation of the symmetry of TST+/IGRA- and TST-/IGRA+.