Table 2.

Incidence rates, rate ratios, and predictive values for incident tuberculosis during follow-up, stratified by Quantiferon-TB Gold Plus results

	QFT-Plus Positive	QFT-Plus Negative
No. of TB cases (microbiologically confirmed and/or clinically diagnosed)	8	2
Participants	140	352
Person-years	261.6	663.0
Incidence rate per 1,000 person-years	30.6 (15.3–61.1)	3.0 (0.8–12.1)
Incidence rate ratio	10.1 (2.2–47.7)
Positive predictive value	5.7 (2.5–10.9)
Negative predictive value	99.4 (98–99.9)
Sensitivity	80.0 (44.4–97.5)
Specificity	72.6 (68.4–76.5)
No. of TB cases (microbiologically confirmed only)	3	1
Incidence rate per 1,000 person-years	11.5 (3.7–35.6)	1.5 (0.2–10.7)
Incidence rate ratio	7.6 (0.8–73.1)
Positive predictive value	2.1 (0.4–6.1)
Negative predictive value	99.7 (98.4–100)
Sensitivity	75.0 (19.4–99.4)
Specificity	71.9 (67.7–75.9)

Definition of abbreviations: QFT-Plus = QuantiFERON-TB Gold Plus; TB = tuberculosis.