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Table 1 The 12 combinations of screening methods and confirmatory tests

From: Choosing algorithms for TB screening: a modelling study to compare yield, predictive value and diagnostic burden

Number Screening method Confirmatory test
  First Second (if 1st positive) First Second (if 1st negative)
1 Prolonged cough*   SSM CD§
2 Prolonged cough*   XP CD§
3 Prolonged cough* CXR SSM CD**
4 Prolonged cough* CXR XP CD**
5 Any TB Symptom+   SSM CD§
6 Any TB Symptom+   XP CD§
7 Any TB Symptom+   SSM CD§
8 Any TB Symptom+ CXR XP CD§
9 CXR abnormality suggestive of TB CXR SSM CD§
10 CXR abnormality suggestive of TB   XP CD§
11 Any CXR abnormality   SSM CD§
12 Any CXR abnormality   XP CD§
  1. SSM = Sputum smear microscopy; XP = Xpert MTB/RIF; TB = tuberculosis; CXR = chest X-ray.
  2. CD = clinical diagnosis, which may in addition to clinical judgment include antibiotic trial and/or CXR for TB abnormalities.
  3. *Cough for 2-3 weeks or longer †Any one out of 4-7 symptoms suggestive of TB.
  4. §We assume that the proportion of persons who receive a clinical diagnosis depends on the negative predictive value of the prior algorithm, as explained in the Methods.
  5. Any CXR abnormality.
  6. **All persons with a negative first confirmatory test receive a clinical diagnosis.