. Author manuscript; available in PMC: 2010 Oct 8.

Published in final edited form as: Int J Tuberc Lung Dis. 2009 Jan;13(1):84–92.

Table 5.

Rate of reversions by baseline IFN-γ value, among household contacts with QFT-positive results at baseline (n = 109)

Baseline IFN-γ response, IU/ml	Retested n	TST-positive at baseline n (%)	Frequency of QFT reversions	Annual incidence of QFT reversions %	P value for trend in QFT reversion rates^*
0.35–0.69	10	5 (50)	2	20.0	0.001
0.70–1.0	5	2 (40)	1	20.0
1.01–3.0	23	15 (65)	4	17.4
3.01–6.0	17	14 (82)	0	0
6.01–10.0	54	49 (91)	0	0
Total	109	85 (78)	7	6.4

Cochrane-Armitage test for trend: χ² = 11.66 (df 1); P = 0.001.

IFN-γ = interferon-gamma; QFT = QuantiFERON-TB Gold In-Tube^®; IU = international units; TST = tuberculin skin test; df = degrees of freedom.