Table 8. Specificity of the serology test based on the ELISA using the PGL-Tb1 or the ESAT-6/CFP10 antigens and their cumulative results in the different groups of individuals classified as low risk of TB infection.

Antigen	n/N	Blood donors	n/N	Healthy subjects	p value of blood donors versus Healthy subjects	n/N	Total
	Percentage (95% CI)
PGL-Tb1*	418/459	91.1 (88.0–93.4)	90/100	90.0 (82.4–94.5)	p = 0.7038	508/559	90.9 (88.2–93.1)
ESAT-6/CFP10**	421/459	91.7 (88.8–94.0)	90/100	90.0 (82.4–94.5)	p = 0.5573	511/559	91.4 (88.7–93.5)
PGL-Tb1 versus ESAT-/CFP10 (p value)		p = 0.8141		p = 1.000			p = 0.8334
Both antigens	389/459	84.8 (81.1–87.9)	80/100	80.0 (70.9–86.8)	p = 0.2336	469/559	83.9 (80.6–86.9)

Footnotes: n/N = number of negative tests/number of tested sera in each group; * Cut-off value for PGL-Tb1: OD = 0.130; ** Cut-off value for ESAT-6/CFP10: OD = 0.100.