How can spectrum bias impact expectations of test performance: a secondary modeling study estimating novel swab-based tuberculosis test outcomes across populations

Background New swab-based near-point-of-care (NPOC) tests offer a potentially lower-cost, simpler alternative to Xpert MTB/RIF Ultra (Xpert-Ultra) testing for tuberculosis (TB) diagnosis. However, it is critical to understand how their performance may differ across diverse populations to inform programmatic rollout and real-world clinical decision-making. Methods We modeled the performance of testing sputum swabs with the MiniDock MTB assay and the Xpert MTB/RIF (Xpert) using positive percentage agreement (PPA) with Xpert-Ultra, disaggregated by semi-quantitative grade. PPA for MiniDock MTB was derived from a random-effects meta-analysis of three diagnostic accuracy studies. PPA for Xpert wa