Figure 1

Algorithms composed of one or more screening methods and one or more confirmatory tests. In panel A one screening tool is applied (e.g. symptoms) and screen positives are further evaluated by one confirmatory test with high sensitivity and high specificity (e.g. Xpert MTB/RIF). In panel B one screening tool is applied (e.g. symptoms) and screen positives are further evaluated by a confirmatory test with low sensitivity (e.g. sputum smear microscopy), and persons with a negative test receive a second test or procedure (e.g. clinical diagnosis, or sputum culture). In panel C two screening tools are applied (e.g. symptoms and chest radiography) and screen positives on either one or on both are further evaluated with a confirmatory test. In panel D two screening tools are applied sequentially. Screen positives on the first screen (e.g. symptoms) undergo a second screen (e.g. CXR) and if also positive on the second a confirmatory test is applied. The single confirmatory test in panels C and D could also be replaced by two-steps as in panel B.