Performance of a Whole-Blood Interferon-Gamma Release Assay with Mycobacterium RD1-Specific Antigens among HIV-Infected Persons

Table 3

Relationship between QFT-G results and CD4⁺ T cell count.

Category by CD4^+ T cell count/𝜇L	Active TB	Results of QFT-G
		Negative	Doubtful positive	Positive	Indeterminate^+
<50   (𝑛=32)	Y (𝑛=3)	2 (67%)	0	0	1 (33%)
	N (𝑛=29)	22 (76%)	0	0	7 (24%)
50–199   (𝑛=29)	Y (𝑛=5)	0	0	5 (100%)	0
	N (𝑛=24)	23 (96%)	0	1 (4%) a	0
200–499   (𝑛=35)	Y (𝑛=1)	0	1 (10%)	0	0
	N (𝑛=34)	32 (94%)	1 (3%)	0	1 (3%)
≥500   (𝑛=11)	N (𝑛=11)	11(100%)	0	0	0
Total	Y (𝑛=9)	2 (22%)	1 (11%)	5 (56%)	1 (11%)
	N (𝑛=98)	88 (90%)	1 (1%)	1 (1%)	8 (8%)

Y: present, N: absent, and a: M. kansasii disease.
(%): percentage of Y or N number in each CD4 category.
⁺Indeterminate results were significantly associated with CD4⁺ T cell count less than 50/𝜇L, compared with CD4⁺ T cell count greater than 50/𝜇L (Fisher’s 𝑃<.0001).