Development of a score derived from full blood count parameters to differentiate individuals with tuberculosis disease from those with tuberculosis infection

In 2022, tuberculosis (TB) caused 1.3 million deaths worldwide, making it the second leading infectious cause of death. Diagnosing TB remains challenging because current immunological tests cannot distinguish between TB disease and TB infection (TBI). Research suggests that ratios such as monocyte-to-lymphocyte, neutrophil-to-lymphocyte, and platelet-to-lymphocyte, along with absolute counts of various blood cells, could help develop a low-cost and easy-to-use diagnostic tool to distinguish TB disease from TBI among IFN-γ release assay (IGRA)-positive subjects without relying on microbiological tests. We enrolled 112 TB-infected subjects and used blood cell count parameters and ratios to develop a TB score that can indicate TB status. We then validated the score in another cohort of IGRA-positive hospitalized patients. We developed a TB score based on 11 blood parameters to identify TB disease among IGRA-positive subjects, with 93% specificity and 71% sensitivity. This score can support physicians in making therapeutic decisions for IGRA-positive subjects, offering a practical approach to differentiate TB disease from TBI.