Abstract:
Background: Children receiving biologic and immunosuppressive therapies are at increased risk of tuberculosis (TB), particularly latent tuberculosis infection (LTBI). Screening in this population is challenging because both tuberculin skin testing and interferon-gamma release assays may have limitations, especially in immunosuppressed children. This study aimed to evaluate the frequency and characteristics of LTBI and to characterize PPD and QuantiFERON-TB findings in children receiving biologic or immunosuppressive therapy.
Methods: We retrospectively evaluated 125 children receiving biologic or targeted immunomodulatory therapy for rheumatologic or autoinflammatory diseases between 2021 and 2023. LTBI was defined as a positive purified protein derivative (PPD) and/or QuantiFERON-TB result in the absence of clinical findings suggestive of active TB. A PPD induration of ≥5 mm was considered positive. Demographic characteristics, underlying
diseases, biologic treatments, TB-related risk factors, PPD and QuantiFERON-TB results, and laboratory findings were analyzed. Patients diagnosed with LTBI received 9 months of isoniazid prophylaxis.
Results: LTBI was identified in 18 of 125 patients (14.4%). The median age was 169 months (IQR, 129–196), and 63 patients (50.4%) were male. No significant differences were observed between LTBI and non-LTBI patients regarding age (p=0.739), sex (p=0.585), BCG scar status (p=1.000), family history of TB (p=0.268), anti-TNF exposure (p=0.538), or individual biologic treatment (p=0.272). PPD results were positive in 14 (77.8%) LTBI patients. QuantiFERON-TB testing was available in 29 patients; seven were positive, and all were
classified as having LTBI. Four LTBI patients had negative PPD results despite positive QuantiFERON-TB, highlighting the potential limitation of relying on PPD alone. All 18 LTBI patients received 9 months of isoniazid. Hyperbilirubinemia occurred in four patients (22.2%), without elevation of liver enzymes or permanent treatment discontinuation. No patient developed active TB during follow-up.
Conclusions: LTBI was identified in 14.4% of children receiving biologic or immunosuppressive therapy. No significant association was observed between LTBI and demographic characteristics, underlying disease, or biologic treatment. The identification of LTBI in patients with negative PPD results supports the complementary use of QuantiFERON-TB in selected immunosuppressed children. Isoniazid prophylaxis was generally well tolerated, although biochemical monitoring remains important during treatment.
Keywords: biologic therapy, latent tuberculosis infection, pediatric, PPD, QuantiFERON-TB, tuberculosis
Biography:
Dr. Cakmak Taskın studied Medicine at the Istanbul University, Cerrahpasa Medical Faculty, Türkiye and graduated in 2011 with a seventh place. She became a pediatric specialist in 2016. She completed her pediatric infection specialist training at Ankara University Faculty of Medicine in 2020. She currently works at Kocaeli City Hospital as a pediatric infection specialist. She has published more than 15 research articles in SCI (E) journals.
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