Health system and environmental factors affecting global progress towards achieving End TB targets between 2015 and 2020.

Background: Health system and environmental factors play a significant role in achieving the World Health Organization (WHO) End Tuberculosis (TB) targets. However, quantitative measures are scarce or non-existent at a global level. We aimed to measure the progress made towards meeting the global End TB milestones from 2015 to 2020 and identify health system and environmental factors contributing to the success. Methods: We obtained data from ten different online data repositories and used principal component analysis to create domain-specific health system performance measures. We used radar charts and dumbbell plots to show the country's progress in ending TB with their health systems. Lastly, we used a linear regression model to identify key health systems and environmental predictors of the percent reduction in TB incidence and mortality. Results: There was a high variation in TB incidence and mortality reduction between countries and WHO regions. Of all countries included, 75 (39.3%) achieved more than a 20% reduction in TB incidence between 2015 and 2020. However, only 31 (16.2%) reached a 35% reduction in TB mortality. The European Region achieved the highest incidence reduction, exceeding the 2020 milestone with a 25% reduction. The African Region also made notable progress, achieving an 18% mortality reduction despite its relatively poor health systems. Health system factors, such as TB financing, TB-specific health service delivery, access to medicine, and governance, were significantly associated with TB mortality reduction between 2015 and 2020. Environmental factors, such as average annual temperature and air particulate matter concentration, were found to have a significant negative effect on TB incidence and mortality reduction. Conclusions: Weak health systems were identified as major barriers to achieving the End TB milestones in most high-burden countries. Hence, strengthening health systems with a special focus on TB financing, service delivery, and access to medicine in these countries should be prioritised to achieve global TB mortality reduction targets. Countries should follow WHO's air quality guidelines and rapidly reduce carbon dioxide and other greenhouse gas emissions to mitigate the impact of environmental factors.