A diagnostic certainty score to support improvements in culture confirmation of TB

Improving the diagnostic confirmation of active TB disease is a key objective of the England & Wales TB Action Plan. However, national data suggest little change in the proportion of TB cases confirmed by positive culture in recent years, with 61% of all cases and 74% of pulmonary TB cases confirmed by culture. We report the introduction of a simple tool that records the diagnostic certainty of tuberculosis during cohort review of new TB cases diagnosed within our TB network in an attempt to improve culture confirmation rates.In North-Central London TB service, we developed a diagnostic certainty score, using results of mycobacterial cultures, molecular diagnostics, microscopy, histology, clinical and radiology results, to grade cases on a 1-5 scale. Since 2017, this has been routinely used as part of our quarterly patient Cohort Reviews. We evaluated the relationship between its introduction and TB culture confirmation.There was a significant improvement in culture confirmation rates from 59% in 2017 to 75% in 2022. By 2022, 86% of pulmonary TB cases were confirmed by TB culture and 55% of extrapulmonary cases.A simple diagnostic certainty score was associated with improved diagnostic confirmation of TB disease and may be helpful for other TB services and TB programmes..