RTBES Radiological Index for Quantitative Assessment of Tuberculosis Evolution: Development and Validation

Abstract Question addressed by the study A radiological index capable of quantifying pulmonary tuberculosis (TB) disease progression on standard Chest X-Ray (CXR) could enhance clinical management and inform therapeutic decision-making. Our objectives were: to develop a radiological index that quantitatively assesses the progression of pulmonary TB in patients over the course of treatment and follow-up, to evaluate its usefulness by using CXRs from a cohort of TB patients, and to validate it with CXRs from an independent cohort of TB patients. Materials/patients and methods An index was developed to identify and classify patterns of radiological findings of both active and inactive pulmonary TB. This index was evaluated in a first cohort comprising a pseudonymized sample of serial CXRs from 21 TB patients at the Perinatal HIV Research Unit (PHRU) in South Africa and validated in a second, larger, independent cohort comprising 50 treated TB patients from the National Institute of Allergy and Infectious Diseases (NIAID) TB Data Portals. The relationship between index values for activity markers and patients’ clinical characteristics was also analysed. Results A radiological index, the RUTI-TB Evolution Score (RTBES), was created and validated in two cohorts, achieving 95.96% interobserver agreement (±2 points). In both cohorts, RTBES for active TB signs decreased over follow-up. Higher baseline RTBES correlated with male sex, higher bacterial loads, and extensive pulmonary involvement (including cavitation and pleural effusions). Baseline RTBES≥2 predicted unfavourable outcomes; 80% of failures/deaths occurred above this threshold. Answer to the question RTBES effectively quantified pulmonary TB severity and tracked treatment evolution on standard CXRs, showing promise as a prognostic tool to inform clinical decision-making.