Correlation between tuberculin skin test and IGRAs with risk factors for the spread of infection in close contacts with sputum smear positive in pulmonary tuberculosis

Table 5 Risk factors associated with the positivity of the TST, QFN-G-IT and T-SPOT.TB in adults

Risk factors	TST			QFN-G-IT			T-SPOT.TB
	n (%)			n (%)			n (%)
	Positive	Negative	p	Positive	Negative	p	Positive	Negative	p
Cough
Yes	34 (94.4)	2 (5.6)	0.929	22 (61.1)	14 (38.9)	0.001	25 (69.5)	11 (30.5)	0.007
Not	31 (93.9)	2 (6.1)		7 (21.2)	26 (78.8)		12 (36.4)	21 (63.6)
Diagnostic delay
<30	35 (97.2)	1 (2.8)	0.244	11 (30.5)	25 (69.5)	0.565	14 (38.9)	22 (61.1)	0.077
30-59	13 (76.5)	4 (23.5)		7 (41.2)	10 (58.8)		7 (41.2)	10 (58.8)
60-89	17 (85)	3 (15)		7 (35)	13 (65)		9 (45)	11 (55)
>89	25 (100)	0 (0)		12 (48)	13 (52)		18 (72)	7 (28)
Room’s size (m ² )
≤50	2 (66.7)	1 (33.3)	0.462	1 (33.3)	2 (66.7)	0.020	2 (66.7)	1 (33.3)	0.023
51-79	15 (78.9)	4 (21.1)		4 (21.1)	15 (78.9)		6 (31.6)	13 (68.4)
≥80	19 (90.5)	2 (9.5)		14 (66.7)	7 (33.3)		16 (76.2)	5 (23.8)
Overcrowding
≤15	7 (87.5)	1 (12.5)	0.800	2 (28.6)	5 (71.4)	0.480	5 (62.5)	3 (37.5)	0.820
>15	26 (83.9)	5 (16.1)		16 (51.6)	15 (48.4)		18 (58.1)	13 (41.9)

TST: tuberculin skin test. QFN-G-IT: Quantiferon-TB Gold in tube.
Diagnostic delay: days between first symptoms and TB diagnostic. Overcrowding: floor area index per person (square meters per person).
Two-tailed statistical test was used to compare the qualitative results of TST, QFN-G-IT and T-SPOT.TB, respectively, between the different categories of the risk factors studied.

ISSN: 1471-2334