Rationale: Although World Health Organization guidelines emphasize contact investigation for tuberculosis-exposed children, data that support chest radiography as a useful tool are lacking.
Objectives: We evaluated the diagnostic and prognostic information of chest radiography in children exposed to TB and measured the efficacy of isoniazid preventive therapy in those with relevant radiographic abnormalities.
Methods: Between September 2009 and August 2012, we enrolled 4,468 TB-exposed children who were screened by tuberculin skin testing, symptom assessment and chest radiography. Those negative for TB disease were followed for one year for the occurrence of new TB diagnoses. We assessed the protective efficacy of isoniazid preventive therapy in children with and without abnormal chest radiographs.
Measurements and main results: Compared to asymptomatic children with normal chest films, asymptomatic children with abnormal radiographs were 25.1-fold more likely to have co-prevalent TB (95%CIs=1.02-613.76) and 26.7-fold more likely to be diagnosed with incident tuberculosis disease during follow-up (95%CIs=10.44-68.30). Among the 29 symptom-negative/CXR-abnormal child contacts, 20% (3/15) of the isoniazid recipients developed incident TB, compared to 57% (8/14) of those who did not receive isoniazid preventive therapy (82% IPT efficacy).
Conclusions: Our results strongly support the use of chest radiography as a routine screening tool for the evaluation of child TB contacts, where this is readily available. Radiographic abnormalities not usually considered suggestive of TB may indicate incipient or subclinical disease, although TB preventive treatment is adequate in most cases.
Keywords: Tuberculosis exposure; chest X-ray; child contacts; preventive therapy; symptom screening.