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. Author manuscript; available in PMC: 2017 Nov 1.
Published in final edited form as: Pediatr Infect Dis J. 2016 Nov;35(11):1165–1168. doi: 10.1097/INF.0000000000001271

Table 3.

Per-sample comparison of the accuracy of TB culture to Xpert with the reference standard set as TB culture positive or histology positive (23/109 samples).

All samples
(%)		 Sensitivity
(N, %, CI 95%)		 Specificity
(N, %, CI 95%)		 PPV
(N, %, CI 95%)		 NPV
(N, %, CI 95%)
Xpert 17 (15.6) 17/23 86/86 17/17 86/92
73.9 (51.6 – 89.8) 100.0 (95.7 – 100.0) 100.0 (81.6 – 100.0) 93.5 (86.3 – 97.6)
AFB only* 15 (13.8) 15/23 85/85 15/15 85/93
65.2 (42.7 – 83.6) 100.0 (95.4 – 100.0) 100.0 (79.6 – 100.0) 91.4 (83.8 – 96.2)
Histology 23 (21.9) 23/23 82/82 23/23 82/82
100.0 (85.7 – 100.0) 100.0 (95.5 – 100.0) 100.0 (85.7 – 100.0) 100.0 (95.5 – 100.0)
*

One AFB not done N=108

N = number of patients, PPV = positive predictive value, NPV = Negative predictive value. AFB = evidence of acid-fast bacilli on Ziehl-Nielson stain.