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. 2017 Oct 26;7:14127. doi: 10.1038/s41598-017-14367-z

Table 2.

Stratified results for sensitivity, specificity and accuracy of the artus MTB assay using culture as diagnostic reference.

Results Test implementation Sensitivity Specificity Accuracy
All samples TP/P¹ % [95%-CI] p-value2 TN/N3 % [95%-CI] p-value TN + TP/N + P % [95%-CI] p-value
All (n = 1634) NAAT1X 22/43 51.2 [35.5; 67.7] n.a. 1542/1591 96.9 [96.0; 97.7] n.a. 1564/1634 95.7 [94.6; 96.6] n.a.
NAAT3X 22/43 51.2 [35.5; 67.7] 1 1567/1591 98.5 [97.8; 99.0] 0.003 1598/1634 97.2 [96.2; 97.9] 0.001
Ct cut-off = 34 11/43 25.6 [13.5; 41.2] 0.014 1568/1591 98.5 [97.1; 99.1] 0.002 1579/1634 96.6 [95.6; 97.5] 0.171
Combination 22/43 51.2 [35.5; 67.7] 1 1566/1591 98.4 [97.7; 98.9] 0.005 1588/1634 97.2 [96.3; 97.9] 0.023
ZN Positive (n = 35) NAAT1X 15/17 88.2 [63.6; 98.5] n.a. 15/18 83.3 [58.6; 96.4] n.a. 30/35 85.9 [69.7; 95.2] n.a.
NAAT3X 15/17 88.2 [63.6; 98.5] 1 17/18 94.4 [72.7; 99.9] 0.289 32/35 91.4 [76.9; 98.2] 0.452
Ct cut-off = 34 9/17 52.9 [27.8; 77.0] 0.023 16/18 88.9 [65.3; 98.6] 0.629 25/35 71.4 [53.7; 85.4] 0.145
Combination 15/17 88.2 [63.6; 98.5] 1 16/18 88.9 [65.3; 98.6] 0.629 31/35 88.6 [73.3; 96.8] 0.720
ZN Negative (n = 1534) NAAT1X 7/26 26.9 [11.6; 47.8] n.a. 1465/1508 97.1 [96.2; 97.9] n.a. 1472/1534 96,0 [94.9; 97.0] n.a.
NAAT3X 7/26 26.9 [11.6; 47.8] 1 1487/1508 98.6 [97.9; 99.1] 0.005 1494/1534 97.4 [96.5; 98.1] 0.027
Ct cut-off = 34 2/26 7.7 [0.9; 25.1] 0.067 1488/1508 98.7 [97.9; 99.2] 0.003 1450/1534 94.5 [93.3; 95.6] 0.062
Combination 7/26 26.9 [11.6; 47.8] 1 1487/1508 98.6 [97.9; 99.1] 0.005 1494/1534 97.4 [96.5; 98.1] 0.027
ZN n.d. (n = 65) NAAT1X 0/0 n.a. n.a. n.a. 62/65 95.4 [87.1; 99.0] n.a. 62/65 95.4 [87.1; 99.0] n.a.
NAAT3X 0/0 n.a. n.a. n.a. 63/65 96.9 [89.3; 99.6] 0.640 63/65 96.9 [89.3; 99.6] 0.648
Ct cut-off = 34 0/0 n.a. n.a. n.a. 64/65 98.5 [91.7; 99.9] 0.310 64/65 98.5 [91.7; 99.9] 0.309
Combination 0/0 n.a. n.a. n.a. 63/65 96.9 [89.3; 99.6] 0.640 63/65 96.9 [89.3; 99.6] 0.648
Respiratory samples
All (n = 1323) NAAT1X 18/26 69.2 [48.2; 85.7] n.a. 1262/1297 97.3 [96.3; 98.1] n.a. 1280/1323 96.7 [95.7; 97.7] n.a.
NAAT3X 18/26 69.2 [48.2; 85.7] 1 1281/1297 98.8 [98.0; 99.3] 0.007 1299/1323 98.2 [97.3; 98.8] 0.019
Ct cut-off = 34 10/26 38.4 [20.2; 59.4] 0.020 1281/1297 98.8 [98.0; 99.3] 0.007 1291/1323 97.6 [96.6; 98.3] 0.198
Combination 18/26 69.2 [48.2; 85.7] 1 1280/1297 98.6 [97.9; 99.2] 0.011 1298/1323 98.1 [97.2; 98.8] 0.027
ZN Positive (n = 29) NAAT1X 14/16 87.5 [61.7; 98.5] n.a. 11/13 84.7 [55.6; 98.1] n.a. 25/29 86.2 [68.3; 96.1] n.a.
NAAT3X 14/16 87.5 [61.7; 98.5] 1 13/13 100 [75.0; 100.0] 0.141 27/29 93.1 [77.2; 99.1] 0.389
Ct cut-off = 34 8/16 50.0 [24.7; 75.4] 0.020 12/13 92.3 [63.9; 99.8] 0.540 20/29 68.9 [49.2; 84.7] 0.115
Combination 14/16 87.5 [61.7; 98.5] 1 12/13 92.3 [63.9; 99.8] 0.540 26/29 89.7 [72.7; 97.8] 0.687
ZN Negative (n = 1293) NAAT1X 4/10 40.0 [12.1; 73.7] n.a. 1250/1283 97.4 [96.4; 98.2] n.a. 1254/1293 97.0 [95.9; 97.9] n.a.
NAAT3X 4/10 40.0 [12.1; 73.7] 1 1267/1283 98.8 [98.0; 99.3] 0.014 1271/1293 98.3 [97.4; 98.9] 0.028
Ct cut-off = 34 2/10 20.0 [2.5; 55.6] 0.330 1268/1283 98.8 [98.1; 99.3] 0.008 1271/1293 98.3 [97.4; 98.9] 0.028
Combination 4/10 40.0 [12.1; 73.7] 1 1267/1283 98.8 [98.0; 99.3] 0.014 1271/1293 98.3 [97.4; 98.9] 0.028
ZN n.d. (n = 1) NAAT1X 0/0 n.a. n.a. n.a. 1/1 100 n.a. n.a. 1/1 100 n.a. n.a.
NAAT3X 0/0 n.a. n.a. n.a. 1/1 100 n.a. n.a. 1/1 100 n.a. n.a.
Ct cut-off = 34 0/0 n.a. n.a. n.a. 1/1 100 n.a. n.a. 1/1 100 n.a. n.a.
Combination 0/0 n.a. n.a. n.a. 1/1 100 n.a. n.a. 1/1 100 n.a. n.a.
Non-respiratory samples
All (n = 311) NAAT1X 4/17 23.5 [6.8; 50.0] n.a. 280/294 95.2 [92.1; 97.4] n.a. 284/311 91.3 [87.5; 94.2] n.a.
NAAT3X 4/17 23.5 [6.8; 50.0] 1 288/294 98.0 [95.6; 99.3] 0.069 292/311 93.9 [90.6; 96.3] 0.220
Ct cut-off = 34 1/17 5.9 [0.2; 28.7] 0.146 287/294 97.6 [95.2; 99.0] 0.120 288/311 92.6 [89.1; 95.3] 0.555
Combination 4/17 23.5 [6.8; 50.0] 1 288/294 98.0 [95.6; 99.3] 0.069 292/311 93.9 [90.6; 96.3] 0.220
ZN Positive (n = 6) NAAT1X 1/1 100 n.a. n.a. 4/5 80.0 [28.4; 99.5] n.a. 5/6 83.3 [35.9; 99.6] n.a.
NAAT3X 1/1 100 n.a. n.a. 4/5 80.0 [28.4; 99.5] 1 5/6 83.3 [35.9; 99.6] 1
Ct cut-off = 34 1/1 100 n.a. n.a. 4/5 80.0 [28.4; 99.5] 1 5/6 83.3 [35.9; 99.6] 1
Combination 1/1 100 n.a. n.a. 4/5 80.0 [28.4; 99.5] 1 5/6 83.3 [35.9; 99.6] 1
ZN Negative (n = 241) NAAT1X 3/16 18.8 [4.1; 45.7] n.a. 215/225 95.6 [92.0; 97.8] n.a. 218/241 90.5 [86.0; 93.9] n.a.
NAAT3X 3/16 18.8 [4.1; 45.7] 1 220/225 97.8 [94.9; 99.3] 0.189 223/241 92.5 [88.4; 95.5] 0.414
Ct cut-off = 34 0/16 0 [0.0; 20.6] 0.069 220/225 97.8 [94.9; 99.3] 0.189 220/241 91.3 [86.9; 94.5] 0.752
Combination 3/16 18.8 [4.1; 45.7] 1 220/225 97.8 [94.9; 99.3] 0.189 223/241 92.5 [88.4; 95.5] 0.414
ZN n.d. (n = 64) NAAT1X 0/0 n.a. n.a. n.a. 61/64 95.3 [86.9; 99.0] n.a. 61/64 95.3 [86.9; 99.0] n.a.
NAAT3X 0/0 n.a. n.a. n.a. 62/64 96.9 [89.2; 99.6] 0.648 62/64 96.9 [89.2; 99.6] 0.648
Ct cut-off = 34 0/0 n.a. n.a. n.a. 63/64 98.4 [91.6; 99.9] 0.310 63/64 98.4 [91.6; 99.9] 0.309
Combination 0/0 n.a. n.a. n.a. 62/64 96.9 [89.2; 99.6] 0.648 62/64 96.9 [89.2; 99.6] 0.648

1TP = true positive (NAAT and reference positive); P = positive (reference positive including also inhibitory samples).

2p-value of a 2-sample test for equality of proportions in comparison with the standard “NAAT1x” test implementation. p-values smaller than 0.05 are printed in bold.

3TN = true negative (NAAT and reference negative); N = negative (reference negative).

4FP = false positive (NAAT positive and reference negative).

5FN = false negative (NAAT negative and reference positive).