ABSTRACT
The objective of this study was to describe the tuberculin test (TT) in children younger than 19 years of age, including the analysis of the utility of a negative TT and to verify the effect of age and BCG vaccination on the TT. To this end, we reviewed the results of the TTs performed during the last 9 years. We classified the TT according to age, BCG vaccination and the reason why the TT was performed. We made graphics of the TT results (GT) and extracted graphics of the TT in children infected with Mycobacterium tuberculosis (CTI) from the GT. We then calculated the probability of a child being infected and having a negative TT (BCG vaccinated: < 15 mm., non BCG vaccinated: < 5 mm). We compared the GT of children 1 year old and children 2 to 18 years of age. We also compared the GT of BCG vaccinated children with the GT of non-vaccinated children. Variance homogeneity tests were used to make comparisons. The results were the following: TT: 20,555. GT (1 year): The number of TT descends, while the induration size augments. GT (2 to 18 years) The number of TT descends while the induration size augments until reaching a size when the frequency of TT begins to increase again, with a maximum of 15 mm. The frequency then decreases again. CTI (2 to 18 years): mean: 15 mm with a standard deviation of +/- 4.8 mm for BCG vaccinated children and +/- 5.2 mm for non-vaccinated children. With these figures, we calculated that 50% of BCG vaccinated infected children and 3% of non-vaccinated infected children have a negative T test. The GT of children 1 year of age were different from the GT of children 2 to 18 years old (p < 0.001). The GT of non-vaccinated children younger than 14 years of age was different from the GT of non-vaccinated children (p < 0.001). we conclude that there is a difference between T tests in children 1 year of age in comparison to those between 2 and 18 years of age. In BCG vaccinated children, 2 to 18 years old, a negative T test did not identify 50% of infected children. BCG vaccination influences T tests in children younger than 14 years of age.
