Retrospective evaluation of latent tuberculosis in immunocompromised patients followed at pediatric infectious diseases department between 2011 to 2018

Aim: Tuberculosis (TB) continues to exist as an important cause of mortality and morbidity worldwide. Latent tuberculosis infection (LTBI), which can progress in to an active disease, causes an increased risk especially in the immunocompromised pediatric patient group. For this reason, it is important to screen the children who are starting or already receiving immunosuppressive therapy in terms of the presence of LTBI. In our study, we aimed to evaluate clinical, laboratory, radiological findings of immunocompromised children and their treatment processes in terms of latent tuberculosis infection. Material and Methods: The study was carried out retrospectively between 2011 to 2018 with immunocompromised patients Pediatric Infection Diseases Department, Istanbul Medical Faculty, Istanbul University. Latent tuberculosis (LTBI) was diagnosed via Mantoux tuberculin skin test (TST) and/or interferon-γ release assay (IGRA), posterior-anterior chest X-ray. Statistical analysis was performed using the Chi-square test with Fisher's Exact test. Results: 190 children have included in the study, 101 of these were girls. Cases were on immunosuppressive therapy due to primary diseases. Among these diseases, 87 (45.8%) were nonspecific uveitis, 61 (32.1%) were chronic inflammatory rheumatological diseases, 26 (13.7%) were inflammatory bowel disease, 10 (5.3%) were chronic immune thrombocytopenic purpura, 3 (1.6%) were solid organ transplantation and 3 (1.6%) were chronic liver/ kidney failure. As for the choice of immunesuppressive therapy, the most prevalent agent was adalimumab which is used in 89 (46. 8%) of the cases, followed by infliximab used in 42 (22.1%), etanercept in 28 (14.7%), rituximab 13 (6.8%), anakinra in 6 (3.2%), canakinumab in 3 (1.6%) and corticosteroids in 9 (4.7%) of the cases. Of the 190 cases in total, 92 (43 female / 49 male) were diagnosed with LTBI. Test result positivity rate was 34.2% (n = 65) in cases screened with TST, and test result positivity rate was 8.3% (n = 10) in cases screened with IGRA. When TST and IGRA were evaluated together, no statistically significant relationship was detected between the two tests (p >0.05). Seventy-four of the 92 patients who diagnosed with LTBI, completed 9 months coarse of isoniazid treatment and and of these 73 did not develop TB disease during follow-up. Despite completion of isoniazid treatment in 1 case using adalimumab, lung TB progressed in the follow-up. Lung TB developped in follow-up in 2 cases who did not have LTBI and using adalimumab. Conclusion: All pediatric cases treated with immunosuppressive drugs should be screened and followed for TB infection. TST is considered to be a safe method in countries with high TB prevalence like our country. Nevertheless, it should be noted that receiving immunosuppressive therapy may decrease TST response and that IGRA application may decrease TB incidence with these patients. Key words: Immunosuppressive Treatment, Pediatric, Latent tuberculosis, TST, IGRA