Cigarette-Smoking Intensity and Interferon-Gamma Release Assay Conversion among Persons Who Inject Drugs: A Cohort Study

Table 2

QFT conversion (IFN-γ ≥ 0.70 IU/mL) at 18 months by quartiles of number of cigarettes smoked among persons who inject drugs in Tijuana, Mexico, 2006–2008.

Number of cigarettes smoked daily (quartiles)	QFT conversion	𝑃 value
0–5	13/30 (43.3)	0.716
6–10	16/36 (44.4)
11–15	15/37 (40.5)
16+	8/26 (30.8)

^∗𝑃 value for the difference in QFT conversion at 18 months across quartiles was generated using the Pearson’s 𝜒² test.
IFN-γ: interferon-gamma; QFT: QuantiFERON-TB Gold In-Tube.