Grace Kaguthi
Kenya Medical Research Institute, Kenya
Title: Chest radiographs for pediatric TB diagnosis: Inter-rater agreement and utility
Biography
Biography: Grace Kaguthi
Abstract
The chest radiograph (CXR) is considered a key diagnostic tool for pediatric tuberculosis (TB) in clinical management and endpoint determination in TB vaccine trials. We set out to compare inter-rater agreement for TB diagnosis in western Kenya. A pediatric pulmonologist and radiologist (experts), a medical officer (M.O), and four clinical officers (C.Os) with basic training in pediatric CXR reading blindly assessed CXRs of infants who were TB suspects in a cohort study. C.Os had access to clinical findings for patient management. Weighted kappa scores summarized inter-rater agreement on lymphadenopathy and abnormalities consistent with TB. Sensitivity and specificity of raters were determined using microbiologically confirmed TB as the gold standard (n=8). A total of 691 radiographs were reviewed. Agreement on abnormalities consistent with TB was poor; k=0.14 (95% CI: 0.10–0.18) and on lymphadenopathy moderate k=0.26 (95% CI: 0.18–0.36). M.O [75% (95% CI: 34.9%–96.8%)] and C.Os [63% (95% CI: 24.5%–91.5%)] had high sensitivity for culture confirmed TB. TB vaccine trials utilizing expert agreement on CXR as a non-microbiologically confirmed endpoint will have reduced specificity and will underestimate vaccine efficacy. C.Os detected many of the bacteriologically confirmed cases; however, this must be interpreted cautiously as they were un-blinded to clinical features.