Detection of latent tuberculosis by tuberculin booster in patients with immunosuppressive treatment

Introduction and objective

One-third of the world's population has latent tuberculosis. Because it can be reactivated by immunosuppressive treatments, screening is suggested. In Colombia, the tuberculin test with the booster is recommended in this population because of the risk of false negative results and anergy caused by treatments. Currently, the number of patients detected with this second test is unknown, so the primary objective is to determine the percentage of additional positive detections.

Materials and methods

From 2017 to 2022, a cross-sectional, analytical study was conducted on a group of patients from a rheumatology service who had a tuberculin test and a booster within a year to check for latent tuberculosis. Over the course of a year and three weeks, we looked at the number of patients whose booster tests showed new findings. A study was conducted to see if there were any differences in treatment based on the first tuberculin result.

Results

A tuberculin test was performed on 674 subjects, of whom 496 were immunosuppressed. From the 382 whose test was negative, 191 and 74 booster tests were performed within a year and three weeks; 8 (4.1%) and 3 (3.6%) were positive, respectively. When evaluating the differences in treatments between the groups with a positive and negative first tuberculin test, significant differences were found. Use of prednisolone at 5 mg or more per day (p = .02) and three immunosuppressants (p = .005) was more frequent in negative tuberculin tests.

Conclusions

It can be said that the booster test raises the number of people with latent tuberculosis by 4%. More use of prednisolone at 5 mg/day or three immunosuppressants in the group with the negative tuberculin test was found to be statistically significant.