Table 2.

Comparison of IFN-γ releasing assay (IGRA) results in patients with active and inactive SLE

Variables	Active SLE (n = 64)	Inactive SLE (n = 54)	p value
IGRA results, n (%)
Positive	4 (6.2)	9 (16.6)	0.073
Negative	31 (48.4)	45 (83.3)	<0.001
Indeterminate	29 (45.3)	0 (0.0)	<0.001
IFN-γ level (IU/mL)
Nil (IU/mL)	0.45 (2.00)	0.09 (0.05)	<0.001
Tuberculosis antigen (IU/mL)	0.43 (1.61)	0.12 (0.21)	0.028
Mitogen (IU/mL)	2.93 (7.09)	11.15 (5.03)	<0.001
Ex vivo IFN-γ production (IU/mL)a	0.92 (4.93)	11.06 (5.27)	<0.001

Values are expressed as the median (interquartile range) or number (percentage)

IFN-γ interferon gamma, IGRA IFN-γ-releasing assay

^aEx vivo IFN-γ production was estimated by calculating the difference in IFN-γ production between the mitogen tube and the nil tube (mitogen minus nil)