Background: Children are at higher risk of tuberculosis (TB) dissemination and extrapulmonary disease, contributing greatly to TB-associated morbidity and long-term sequelae. However, there are very few studies that assess the impact and clinical spectrum of pediatric extrapulmonary TB (EPTB) in low-prevalence regions.
Methods: Children <18 years of age diagnosed with TB in Madrid region (2005-2013) were reviewed. We compared the epidemiology, clinical characteristics and the performance of diagnostic tests in childhood extrapulmonary and pulmonary disease. We performed a multivariate logistic regression to identify factors associated with EPTB.
Results: During the study period, 93 of 526 pediatric TB cases had EPTB (17.7%). The most common site was lymphatic TB (34.5%). The source case was not identified in most extrapulmonary cases, contrary to pulmonary TB (28% vs. 63.3%; P < 0.001). The tuberculin-skin-test induration was smaller in EPTB cases (<5 mm 22% vs. 5%; P < 0.001), but the sensitivity of interferon-gamma-release-assays was similar (76.9% vs. 79.4%). Children with EPTB presented higher rate of bacteriologic confirmation (66% vs. 49.4%; P < 0.01), and higher incidence of multidrug resistant TB (8.2% vs. 1.6%; P = 0.03). Complications were present in 40.2% extrapulmonary cases. EPTB was associated with the child's foreign origin [odds ratio (OR) 2.3 (1.1-5.3)], immune disorders [OR 5.8 (1.9-17.1)] and drug resistance [OR 2.4 (1.1-5.4)].
Conclusions: In our low-prevalence region, childhood EPTB was linked to immigrant status, immune disorders and drug resistance, and presented high rate of complications. Our study underscores the relevance of improved diagnostic tools and systematic TB screening in high risk populations.