Table 2

Accuracy of Xpert MTB/RIF for the detection of culture-positive TB in bronchoalveolar lavage fluid

 All patients
n=154		HIV uninfected
n=84		HIV infected
n=46
Sensitivity, %
(95% CI)		Specificity, %
(95% CI)		Sensitivity, %
(95% CI)		Specificity, %
(95% CI)		Sensitivity, %
(95% CI)		Specificity, %
(95% CI)
Smear microscopy57.7 (39 to 74.5)
15/26		99.3 (95.7 to 99.9)
126/127		58.4 (32 to 80.7)
7/12		100 (95 to 100)
72/72		57.2 (25.1 to 84.2)
4/7		97.4 (86.6 to 99.6)
37/38
MTB/RIF performed on uncentrifuged BALF92.6 (76.7 to 98)
25/27
(p=0.001)		96 (91 to 98.3)
120/125		100 (75.8 to 100) 12/12
(p=0.02)*		95.9 (88.5 to 98.6)
69/72		75 (41 to 92.9)
6/8		94.5 (81.9 to 98.5)
34/36
MTB/RIF performed on uncentrifuged BALF in patients who were smear negative81.9 (52.4 to 94.9)
9/11		96.8 (92 to 98.8)
120/124		100 (56.6 to 100)
5/5		95.9 (88.5 to 98.6)
69/72		33.4 (6.2 to 79.3)
1/3		97.2 (85.5 to 99.5)
34/35
MTB/RIF performed on a resuspended pellet of centrifuged BALF94.8 (75.4 to 99.1)
18/19		91.4 (83.3 to 95.8)
74/81		88.9 (56.6 to 98.1)
8/9		95.3
(84.3 to 98.7)
40/42		100
(43.9 to 100)
3/3		87
(67.9 to 95.5)
20/23
Two MTB/RIF assays (performed on uncentrifuged and centrifuged BALF, respectively)100 (83.2 to 100)
19/19		89.9 (81.3 to 94.8)
71/79		100 (70.1 to 100)
9/9		92.9 (81 to 97.6)
39/42		100 (43.9 to 100)
3/3		85.8 (65.4 to 95.1)
18/21
PPV†
(95% CI)		NPV†
(95% CI)		PPV†
(95% CI)		NPV†
(95% CI)		PPV†
(95% CI)		NPV†
(95% CI)
Smear microscopy93.8 (71.7 to 98.9)
15/16		92 (86.2 to 95.5)
126/137		100 (64.6 to 100)
7/7		93.6 (85.7 to 97.2)
72/77		80 (37.6 to 96.4)
4/5		92.5 (80.2 to 97.5)
37/40
MTB/RIF performed on uncentrifuged BALF83.4 (66.5 to 92.7)
25/30		98.4 (94.3 to 99.6)
120/122		80 (54.9 to 93)
12/15		100 (94.8 to 100)
69/69		75 (41 to 92.9)
6/8		94.5 (81.9 to 98.5)
34/36
MTB/RIF performed on uncentrifuged BALF in patients who were smear negative69.3 (42.4 to 87.4)
9/13		98.4 (94.3 to 99.6)
120/122		62.5 (30.6 to 86.4)
5/8		100 (94.8 to 100)
69/69		50 (9.5 to 90.6)
1/2		94.5 (81.9 to 98.5)
34/36
MTB/RIF performed on a resuspended pellet of centrifuged BALF72 (52.5 to 85.8)
18/25		98.7% (92.9 to 99.8)
74/75		80 (49.1 to 94.4)
8/10		97.6 (87.5 to 99.6)
40/41		50 (18.8 to 81.3)
3/6		100 (83.9 to 100)
20/20
Two MTB/RIF assays (performed on uncentrifuged and centrifuged BALF, respectively)70.4 (51.6 to 84.2)
19/27		100
(94.9 to 100)
71/71		75
(46.8 to 91.2)
9/12		100
(91.1 to 100)
39/39		50
(18.8 to 81.3)
3/6		100
(82.5 to 100)
18/18

  • †Based on TB prevalences of 18%, 14% and l8% overall and in the patient groups with HIV infection and without HIV infection.

  • BALF, bronchoalveolar lavage fluid; NPV, negative predictive value; PPV, predictive value; TB, tuberculosis.