Figure 2. Odds ratio and confidence interval of 95% for the Tuberculin Skin Test –TST− (blue) and QuantiFERON-TB Gold in-Tube –QFT− (red) positive results according to the intensity of exposure to index case by Mycobacterium tuberculosis contact score (MTC-score).

The MTC-score is from 0 to 15 and is based on the assumption that the gradient of Mtb exposure is a composite function of the infectivity of the index case (0–4), the duration of exposure -hours per day- (0–4), the relationship to index case (0–4) and the type of exposure (0–3).