Pediatric Pulmonology. 2020;1–8. wileyonlinelibrary.com/journal/ppul © 2020 Wiley Periodicals LLC | 1 Received: 1 April 2020 | Accepted: 12 July 2020 DOI: 10.1002/ppul.24963 ORIGINAL ARTICLE: INFECTION AND IMMUNITY Determination of tuberculin skin test for isoniazid prophylaxis in BCG vaccinated children who are using anti‐TNF agents for rheumatologic diseases Ayse Ayzit Kilinc MD 1 | Pinar Onal MD 2 | Berrak Oztosun MD 3 | Mehmet Yildiz MD 4 | Amra Adrovic, 4 Assoc Prof | Sezgin Sahin, 4 Assoc Prof | Kenan Barut, 4 Assoc Prof | Haluk Cokugras, 1 Prof Dr | Ozgur Kasapcopur, 4 Prof Dr 1 Department of Pediatric Pulmonology, Cerrahpasa Faculty of Medicine, İstanbul University‐Cerrahpasa, İstanbul, Turkey 2 Department of Pediatric Infectious Diseases, Cerrahpasa Faculty of Medicine, İstanbul University‐Cerrahpasa, İstanbul, Turkey 3 Department of Pediatrics, Cerrahpasa Faculty of Medicine, İstanbul University‐Cerrahpasa, İstanbul, Turkey 4 Department of Pediatric Rheumatology, Cerrahpasa Faculty of Medicine, İstanbul University‐Cerrahpasa, İstanbul, Turkey Correspondence Ayse Ayzit Kilinc, MD, Yesilkoy Mah. Penbe Menekse Sokak, Nokta Apt. No: 13/9 Bakirkoy, Istanbul 34260, Turkey. Email: kilincayse203@gmail.com Abstract Objective: The use of tumor necrosis factor inhibitors (anti‐TNF) has a risk of ac- tivating latent tuberculosis infection (LTBI). This study was performed to investigate LTBI according to tuberculin skin test (TST) size and to determine the frequency of tuberculosis (TB) in bacillus Calmette‐Guerin (BCG)‐vaccinated children receiving anti‐TNF treatment for rheumatological disease. Materials and Methods: The study consisted of 559 children. Information on de- mographics, anti‐TNF agents, TST size, and isoniazid (INH) prophylaxis was re- corded. Patients (n = 254) with TST size ≥5 mm were divided into three groups according to TST size and INH prophylaxis: group 1, TST size 5 to 9 mm and no INH prophylaxis; group 2, TST size 5 to 9 mm with INH prophylaxis; and group 3, TST size ≥10 mm with INH prophylaxis. Results: The 559 patients comprised 314 (56.3%) females and 245 (43.6%) males; they had a mean age of 13.1 ± 4.1 years. The mean TST size in all patients was 4.2 ± 4.7 mm. Group 1 consisted of 76 (29.9%) patients, group 2 consisted of 88 (34.6%) patients, and group 3 consisted of 90 (35.4%) patients. The mean TST sizes for the three groups were 6.8 ± 3.1 mm, 7.2 ± 3.2 mm, and 13.9 ± 2.8 mm, re- spectively. New TB was diagnosed in only two (0.35%) patients. Both of them were in group 3. Conclusions: A TST size of ≥10 mm in BCG‐vaccinated children receiving anti‐TNF treatment may distinguish children at high risk for reactivation of LTBI. KEYWORDS antitumor necrosis factor, BCG, rheumatological disease, tuberculin skin test, tuberculosis 1 | INTRODUCTION Tumor necrosis factor (TNF) plays a critical role in the pathogen- esis of several systemic rheumatological diseases. Marked pro- gress has been made in treating these diseases, and clinical outcomes have significantly improved with the use of tumor necrosis factor inhibitors (anti‐TNF), especially in patients re- fractory to conventional treatment methods. 1,2 However, anti‐TNF agents have been associated with increased risk of various in- fectious diseases such as sepsis, pyelonephritis, herpes zoster in- fection, severe bacterial pneumonia, and reactivation of latent tuberculosis infection (LTBI). 3 Although the reasons are not fully