Despite the widespread use of a tuberculin skin test, it is not so simple to correctly determine the result of the Mantoux reaction. In addition, there is not enough data on how staff at children's medical institutions can properly assess the Mantoux reaction, as well as information on the accuracy of the different methods for determining the results of a skin test. to tuberculin.

Scientists at Madigan Army Medical Center, Washington, USA conducted a study to determine how well pediatricians assess the results of a tuberculin skin test, as well as the most reliable method of evaluating a test from Mantoux.

The study involved 16 full-time pediatricians, 13 residents, 20 nurses and 8 medical students working in a large pediatric clinic. Each participant was offered a 15 mm Mantoux reaction with a positive reaction known for evaluation. The evaluation of a skin test was possible by any method at the request of the participants. The main objective of the study was to find out what percentage of health workers identified the reaction as greater than 10 mm (this result was considered to be correct).

While 77% (44 of 57) of the study participants identified the Mantoux reaction as being greater than 10 mm, 18% (10 of 57) judged it to be negative (less than 5 mm). Participants used a variety of measurement methods. 18 health care providers preferred the "ballpoint pen method" (that is, with a ballpoint pen, dots are placed around the edges of the papule and a measurement is taken). It was these medical workers who were more likely to correctly determine the skin reaction (ie, more than 10 mm) than those who used other methods (94% vs 69% ; p = 0.04) At the same time, those who used the "ballpoint pen method" were less likely to erroneously assess the results of a tuberculin skin test of less than 5 mm (0% vs 26%; p = 0.02).

Thus, most health workers, regardless of their training and experience, define the Mantoux reaction of 15 mm as greater than 10 mm, that is to say correctly, but some doctors evaluate it as negative.

The study found that using the "ball point pen method" can reduce the number of misinterpretations of a tuberculin skin test. Based on these results, the scientists concluded that teaching the rules for evaluating the results of a tuberculin skin test should be included in the training programs of health professionals.