Table 3 The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of smear, MGIT and Xpert for the diagnosis of pediatric TB
From: Prospective evaluation of GeneXpert for the diagnosis of HIV- negative pediatric TB cases
Sensitivity% (x/n); [95%CI] | Specificity% (x/n); [95%CI] | PPV% (x/n); [95%CI] | NPV% (x/n); [95%CI] | ||
|---|---|---|---|---|---|
Gold standard 1 = Confirmed TB | Per patient analysis (n = 150) | ||||
Xpert | 68.4 (26/38) [53.6, 83.2] | 98.2 (110/112) [95.7; 100] | 92.9 (26/28) [83.3; 100] | 90.2 (110/122) [84.9, 95.5] | |
Smear | 31.6 (12/38) [16.8; 46.4] | 100 (112/112)* | 100 (12/12)* | 81.2 (112/138) [74.6; 87.7] | |
Per sample analysis (n = 294) | |||||
Xpert | 57.1 (44/77) [42.8, 71.5] | 99.1 (215/217) [97.8, 1.00] | 95.7 (44/46) [89.7, 100] | 86.8 (219/248) [81.0; 92.6] | |
Smear | 18.2 (14/77) [8.5; 27.9] | 100 (215/217) | 100 (14/14) | 77.5 (217/280) [70.7; 84.3] | |
Gold standard 2 = Clinical diagnosis | Per patient analysis (n = 150) | ||||
Smear | 9.2 (12/131) [4.2, 14.1] | 100 (19/19) | 100 (12/12) | 13.8 (19/138) [8.0, 19.5] | |
MGIT | 29.0 (38/131) [21.2, 36.8] | 94.7 (18/19) [84.7, 100] | 97.4 (38/39) [92.5, 100] | 16.2 (18/111) [9.4, 23.1] | |
Xpert | 20.6 (27/131) [13.7, 27.5] | 94.7 (18/19) [84.7,100] | 96.4 (27/28) [89.6,100] | 14.8 (18/122) [8.5, 21.1] | |
Per sample analysis (n = 294) | |||||
Smear | 5.4 (14/257) [2.2; 8.7] | 100 (37/37) | 100 (14/14) | 13.2 (37/280) [7.6; 18.8] | |
MGIT | 23.3 (60/257) [16.7; 30.0] | 94.6 (35/37) [84.3; 100] | 96.8 (60/62) [90.6; 100] | 15.1 (35/232) [8.6; 21.5] | |
Xpert | 17.5 (45/257) [11.3; 23.8] | 97.3 (36/37) [92.1; 100] | 97.8 (45/46) [93.6; 100] | 14.5 (36/248) [8.4; 20.6] | |