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

BMC Infectious Diseases

Table 1 The 12 combinations of screening methods and confirmatory tests

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^§

SSM = Sputum smear microscopy; XP = Xpert MTB/RIF; TB = tuberculosis; CXR = chest X-ray.
CD = clinical diagnosis, which may in addition to clinical judgment include antibiotic trial and/or CXR for TB abnormalities.
*Cough for 2-3 weeks or longer †Any one out of 4-7 symptoms suggestive of TB.
^§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.
^‡Any CXR abnormality.
**All persons with a negative first confirmatory test receive a clinical diagnosis.

ISSN: 1471-2334