Table 7.

Validity of radiologists using different tags and different reference standards.

	Situation A	Situation B	Situation C
Sensitivity (95% CI)	0.56 (0.50, 0.62)	0.58 (0.51, 0.65)	0.94 (0.91, 0.97)
Specificity (95% CI)	0.80 (0.77, 0.83)	0.80 (0.77, 0.83)	0.21 (0.18, 0.24)
Positive Predictive Value (95% CI)	0.59 (0.53, 0.65)	0.47 (0.41, 0.54)	0.38 (0.35, 0.42)
Negative Predictive Value (95% CI)	0.78 (0.74, 0.81)	0.86 (0.83, 0.89)	0.88 (0.81, 0.92)

Situation A: ‘TB screen’ tag compared to microbiological reference standard of smear, culture or GeneXpert. Situation B: ‘TB screen’ tag compared to microbiological reference standard of culture or GeneXpert. Situation C: ‘Abnormal’ tag compared to microbiological reference standard of smear, culture or GeneXpert.