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Fig. 1 | BMC Medicine

Fig. 1

From: Informing decision-making for universal access to quality tuberculosis diagnosis in India: an economic-epidemiological model

Fig. 1

Schematic representation of the tuberculosis (TB) diagnostic process in the public sector. Upon accessing the public sector for TB diagnosis, individuals are assumed to undergo an initial evaluation that includes Xpert MTB/RIF (or sputum smear microscopy prior to Xpert implementation). A proportion of those encounters will result in successful diagnosis followed by successful treatment (green arrow) or pre-treatment loss to follow-up (LTFU) estimated at 13% for both centralized and decentralized scenarios (red arrow). These individuals may undergo other diagnostic encounters, but those encounters do not result in TB diagnosis, and the cost of those encounters is not considered by the model. In addition to these individuals, another proportion of individuals (also estimated at 13% in the base case) are expected to experience pre-treatment LTFU due to diagnostic delays in the centralized scenario (blue arrow). These individuals can return for a future visit in which Xpert is again performed and TB treatment is successfully initiated. The assumption that all incremental LTFU is followed by a second encounter is conservative and may underestimate the impact of Xpert in the decentralized scenario. Finally, individuals receiving TB treatment who fail to recover will undergo a separate encounter after treatment completion in which Xpert is performed and used to guide second-line therapy

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